Water distillation device, method, and system

Abstract

To provide a water vapor distillation system.SOLUTION: The system includes a water vapor distillation device configured to receive a volume of source water from a fluid source and produce distillate. The device comprises: a concentrate flow path comprising a concentrate output; a distillate flow path comprising a distillate output; at least one source proportioning valve; a first heat exchanger comprising at least a portion of the distillate flow path; a second heat exchanger including at least a portion of the concentrate flow path, in which the first heat exchanger and the second heat exchanger are in fluid flow communication with the fluid source; a distillate sensor assembly which is in communication with the distillate flow path and located downstream of the first heat exchanger, and configured to generate a distillate temperature measurement value; and a controller configured to control the source proportioning valves.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to water distillation, and more particularly to steam distillation apparatus, methods, and systems. [Background technology]

[0002] (Background information) A dependable source of purified water is essential for much of humanity. For example, the Canadian International Development Agency reports that approximately 1.2 billion people lack access to safe drinking water. Published reports attribute millions of deaths, primarily children, to water-related diseases each year. Many water purification techniques are known, including carbon filters, chlorination, pasteurization, and reverse osmosis. Many of these techniques are significantly affected by variations in water quality and do not address various common contaminants, such as bacteria, viruses, organic matter, arsenic, lead, mercury, and pesticides, that may be found in water supplies in developing countries and elsewhere. Some of these systems require access to sources of consumables, such as filters or chemicals. Furthermore, some of these techniques are well suited only for centralized, large-scale water systems, requiring both significant infrastructure and highly trained operators. The ability to produce reliable purified water, regardless of the water source, on a smaller, decentralized scale, without the need for consumables and constant maintenance, is highly desirable, especially in the developing world.

[0003] The use of vapor compression distillation to purify water is well known and can address many of these concerns. However, poor financial resources, limited technological assets, and low population densities in much of the developing world that make it impractical to build centralized, large-scale water systems also limit the availability of adequate, affordable, and reliable electricity to operate vapor compression distillation systems and hinder the ability to properly maintain such systems. In such situations, improved vapor compression distillation systems and associated components that increase efficiency and production capacity while reducing the power budget required for system operation and the amount of system maintenance required may provide a solution. Summary of the Invention [Means for solving the problem]

[0004] (summary) According to one embodiment of the present disclosure, a steam distillation system for providing a distillate at a controlled temperature is disclosed. The steam distillation system includes a steam distillation device configured to receive a volume of source water from a fluid source and produce a distillate, the device comprising: a concentrate flow path having a concentrate output; a distillate flow path having a distillate output; at least one source proportional valve; a first heat exchanger comprising at least a portion of the distillate flow path; a second heat exchanger comprising at least a portion of the concentrate flow path, the first heat exchanger and the second heat exchanger being in fluid flow communication with the fluid source; a distillate sensor assembly in communication with the distillate flow path and located downstream of the first heat exchanger, the distillate sensor assembly being configured to generate a distillate temperature measurement; and a controller configured to control the source proportional valve, the controller being configured to receive the distillate temperature measurement, determine a difference between a first target temperature and the distillate temperature measurement, and divide source water from the fluid source between the first heat exchanger and the second heat exchanger based on the difference between the first target temperature and the distillate temperature measurement.

[0005] According to certain embodiments of the present disclosure, a water purification system for outputting a distillate at a controlled temperature may include a distillation device in selective fluid communication with a fluid source via a set of source proportional valves. The distillation device may have a concentrate output and a distillate output coupled to the concentrate flow path and the distillate flow path, respectively. The system may further include a first heat exchanger including a portion of the distillate flow path and a second heat exchanger including a portion of the concentrate flow path. The flow path from the fluid source may be in heat exchange relationship with each of the first and second heat exchangers. The system may further include a distillate sensor assembly in communication with the distillate flow path downstream of the portion of the distillate flow path contained within the first heat exchanger. The distillate sensor assembly may be configured to generate a distillate temperature measurement. The system may further include a controller configured to govern operation of the source proportional valve and, in a first mode of operation, to split the incoming flow from the fluid source between the first heat exchanger and the second heat exchanger based on a delta between the first target temperature and the measured distillate temperature.

[0006] In some embodiments, the controller may be configured to determine a total source proportional valve duty cycle that dictates the amount of input flow from the fluid source. In some embodiments, the system may further include a concentrate reservoir and a concentrate level sensor. The controller may be configured to determine the total source proportional valve duty cycle based on a concentrate accumulation rate calculated from the level measurement output of the concentrate level sensor and a target concentrate accumulation rate. In some embodiments, the controller may be configured to govern operation of the source proportional valve in a second operating mode to allocate the entire total source proportional valve duty cycle to the source proportional valve controlling the source flow to the second heat exchanger and to open the source proportional valve controlling the source flow to the first heat exchanger with an additional duty cycle that is equal to or less than a predefined limit. In some embodiments, the predefined limit may be selected from a list consisting of 5%, 2%, less than 2%, and zero. In some embodiments, the first operating mode may be a low temperature distillate production state, and the second operating mode may be a high temperature distillate production state. In some embodiments, the controller may be configured, in the second operating state, to open the source proportional valve controlling the source flow to the first heat exchanger based on a second target temperature and a delta between the second target temperature and the current concentrate temperature. In some embodiments, the second target temperature may be at least 65° C. higher than the first target temperature. In some embodiments, the second target temperature may be at least 50° C. higher than the first target temperature. In some embodiments, the second target temperature may be greater than 95° C. and less than 100° C. In some embodiments, the second target temperature may be 96° C. In some embodiments, the second target temperature may be at least twice the first target temperature. In some embodiments, the second target temperature may be at least 2.5 times the first target temperature. In some embodiments, the second target temperature may be at least 3.5 times the first target temperature. In some embodiments, the system may further include an evaporator level sensor disposed in an evaporator reservoir in fluid communication with the evaporator of the distillation device.In the second mode, the controller may be configured to determine the total source proportional valve duty cycle based, at least in part, on an evaporator level data signal indicating the level of the water column in the evaporator reservoir. In some embodiments, the first target temperature is at least 20°C but may be no greater than 25°C. In some embodiments, the system may further include a source fluid temperature sensor. The controller may be configured to determine the first target temperature based, at least in part, on a source fluid temperature measurement received from the source fluid temperature sensor. In some embodiments, the system may further include a concentrate sensor assembly in communication with the concentrate flow path downstream of the portion of the concentrate flow path included in the second heat exchanger. The concentrate sensor assembly may be configured to generate a concentrate temperature measurement. In some embodiments, the controller is configured to open the source proportional valve controlling the source flow to the second heat exchanger based, at least in part, on a delta between the third target temperature and the concentrate temperature measurement. In some embodiments, the third target temperature may be a historical average of the concentrate temperature. In some embodiments, the controller may be configured to open the source proportional valves restricting the source flow to the second heat exchanger based, at least in part, on a minimum limit. In some embodiments, the minimum limit may be greater than a predefined duty cycle or a predefined percentage of the combined duty cycle for all of the source proportional valves. In some embodiments, the predefined duty cycle may be 5%. In some embodiments, the predefined percentage may be 10%. In some embodiments, the controller may be located in an electronics box in heat transfer relationship with a flow path from the fluid leading to the source second heat exchanger. In some embodiments, the controller may be configured to determine an electronics box cooling duty cycle command and open the source proportional valves restricting the source flow to the second heat exchanger based, at least in part, on the electronics box cooling duty cycle command. In some embodiments, the electronics box cooling duty cycle may be determined based, at least in part, on a delta between a target electronics box temperature and an electronics box temperature measurement collected from an electronics box temperature sensor configured to measure the temperature of the electronics box and in data communication with the controller. In some embodiments, the distillate sensor assembly may include redundant temperature sensors. In some embodiments, the distillate sensor assembly may include redundant temperature sensors and redundant conductivity sensors. In some embodiments, the first and second heat exchangers may be spirals formed by wrapping the heat exchangers around the exterior of the distillation device.

[0007] According to certain embodiments of the present disclosure, a fluid vapor distillation apparatus may include at least one controller and a source inlet in selective fluid communication with a fluid source via at least one valve. The fluid vapor distillation apparatus may further include an evaporator in fluid communication with the source inlet. The fluid vapor distillation apparatus may further include a vapor chest coupled to the evaporator and in fluid communication with the compressor. The fluid vapor distillation apparatus may further include a concentrate reservoir attached to the vapor chamber via an inlet path. The concentrate reservoir may be positioned laterally relative to the vapor chamber such that at least a portion of the concentrate reservoir is flush with the vapor chamber. The fluid vapor distillation apparatus may further include a condenser in fluid communication with the outlet of the compressor via a linear flow path. The linear flow path may include a condenser inlet having a fenestrated section with a plurality of fenestrations. The fenestrations may establish a flow path from the condenser inlet to the condenser. The fluid vapor distillation apparatus may further include a product process stream reservoir coupled to the condenser by a product reservoir inlet. The product process stream reservoir may be positioned laterally relative to the condenser such that at least a portion of the product process stream reservoir is flush with the condenser.

[0008] In some embodiments, the inlet path may include an obstruction. In some embodiments, the obstruction may include a plate. The plate may have a section extending into the concentrate reservoir at an angle generally perpendicular to the inlet path. In some embodiments, the obstruction may extend into the concentrate reservoir and divide the concentrate reservoir into a first portion and a second shielding portion. In some embodiments, the fluid steam distillation apparatus may further include a vent path extending from the concentrate reservoir to the steam chamber. In some embodiments, the vent path may extend generally parallel to and above the inlet path relative to gravity. In some embodiments, the product reservoir inlet may be adjacent to the product accumulation surface of the condenser. In some embodiments, the compressor may be driven by a motor mounted in a receiving well fitted into the side of the steam chamber. In some embodiments, the compressor may include an impeller passing through at least a portion of the steam chamber and rotating about an axis offset from but parallel to the longitudinal axis of the steam chamber.

[0009] According to another embodiment of the present disclosure, a water vapor distillation apparatus may include a water reservoir and an evaporator having a first side in fluid communication with the water reservoir. The evaporator may have a second side in fluid communication with the steam chamber. The water vapor distillation apparatus may further include a concentrate reservoir attached to the steam chamber via an inlet path having a first portion and a second portion. The second portion may be at least partially formed by an obstruction. The obstruction may extend transversely into the concentrate reservoir relative to the first portion and divide the concentrate reservoir into an unshielded section and a shielded section. The water vapor distillation apparatus may further include a float assembly disposed within the shielded section. The float assembly may be displaceable over a displacement range that includes a point at the same height as all steam chamber liquid levels within an expected range of steam chamber liquid levels. The water vapor distillation apparatus may further include a sensor configured to monitor the position of the float assembly and output a data signal indicative of the liquid level in the steam chamber based on the position of the float assembly. The water vapor distillation apparatus may further include a compressor having an inlet establishing fluid communication with the vapor chest and an outlet establishing fluid communication with the condenser.

[0010] In some embodiments, the sensor may be an encoder. In some embodiments, the float assembly may include at least one magnet. In some embodiments, the sensor may be a Hall Effect sensor. In some embodiments, the float assembly may be mounted on a pivot. In some embodiments, the float assembly may be displaceable about the pivot. In some embodiments, the obstruction may extend into the concentrate reservoir at an angle generally perpendicular to the first portion of the inflow path. In some embodiments, the water vapor distillation apparatus may further include a vent path extending from the concentrate reservoir to the steam chamber. In some embodiments, the vent path may extend parallel to and above the first portion of the inlet path. In some embodiments, the vent path may have a smaller cross-sectional area than the first portion of the inlet path.

[0011] According to another embodiment of the present disclosure, a water vapor distillation apparatus may include a water reservoir having a source fluid input. The water vapor distillation apparatus may further include an evaporator having a first side in fluid communication with the source fluid input via the water reservoir and a second side in fluid communication with the steam chamber. The evaporator may be configured to convert source fluid from the source fluid input into low-pressure steam and condensate as the source fluid travels toward the steam chamber. The water vapor distillation apparatus may further include a condensate reservoir attached to and positioned laterally relative to the steam chamber. The condensate reservoir may include a condensate level sensor configured to monitor the level of condensate in the steam chamber and generate a data signal indicative of the condensate level. The water vapor distillation apparatus may further include a compressor having a low-pressure steam inlet establishing fluid communication with the steam chamber and a high-pressure steam outlet establishing fluid communication with the condenser via a condenser inlet. The water vapor distillation apparatus may further include a condenser in heat transfer relationship with multiple exterior surfaces of the evaporator. The condenser may be configured to condense the high-pressure vapor stream from the compressor by contacting the high-pressure vapor stream with multiple exterior surfaces of the evaporator. The condenser may include a condensing portion and a condensate accumulation or storage portion. The water vapor distillation apparatus may further include an auxiliary condensate reservoir in fluid communication with the condensate accumulation portion. The auxiliary condensate reservoir may be attached to the condenser adjacent to an accumulation surface of the accumulation portion, and the auxiliary condensate reservoir may include a condensate level sensor configured to monitor the level of condensate in the accumulation portion and generate a data signal indicative of the percentage of the accumulation portion filled with condensate.

[0012] In some embodiments, the accumulation portion may have a volume of less than 10 liters. In some embodiments, the plurality of exterior surfaces may be exterior surfaces of a plurality of evaporator tubes contained within the evaporator. In some embodiments, the plurality of exterior surfaces may be exterior surfaces of 90 to 100 evaporator tubes contained within the evaporator. In some embodiments, the plurality of exterior surfaces may be exterior surfaces of 70 to 80 evaporator tubes contained within the evaporator. In some embodiments, the condensate level sensor may include a float assembly mounted on a pivot. In some embodiments, the float assembly may be displaceable about the pivot over a range of displacement that includes a point at the same height as the range of levels defined by the accumulation portion. In some embodiments, the concentrate level sensor may include a float assembly disposed within a shielded section of the concentrate reservoir separated from an unshielded portion of the concentrate reservoir by a barrier. In some embodiments, the float assembly may be mounted on a pivot and may be displaceable about the pivot over a range of displacement that includes a point at the same height as all steam chamber concentrate levels within the expected range of steam chamber liquid levels. In some embodiments, the concentrate level sensor may be disposed within a sleeve that forms the barrier.

[0013] According to another embodiment of the present disclosure, a concentrate level control system for a fluid vapor distillation apparatus may include a source fluid input in selective fluid communication with a source fluid reservoir via at least one input valve. The concentrate level control system may further include an evaporator in fluid communication with the source input and in fluid communication with a steam chamber. The evaporator may be configured to convert source fluid from the source fluid input into a vapor flow and a concentrate flow as the source fluid travels toward the steam chamber. The concentrate level control system may further include a concentrate reservoir attached to the steam chamber via an inlet path, disposed laterally therewith, and including an outlet in selective communication with a concentrate destination via an outlet valve. The concentrate level control system may further include a concentrate level sensor configured to generate a data signal indicative of the concentrate level in the steam chamber. The concentrate level control system may further include a controller configured to deliberately modify the concentrate level in a predetermined pattern by regulating operation of the at least one inlet valve via the fluid input control loop and analyzing the data signal. The controller may be further configured to actuate the outlet valve to a closed state when the data signal indicative of the concentrate level is below a first threshold, and to actuate the outlet valve to an open state when the concentrate level is above a second threshold.

[0014] In some embodiments, the predetermined pattern may produce a sawtooth waveform when the concentrate level is plotted over time. In some embodiments, the period of the sawtooth waveform may depend, at least in part, on the fluid input command from the fluid input control loop. In some embodiments, the fluid input command may be determined based on a predefined target concentrate production rate. In some embodiments, the controller may be configured to operate in multiple operating states, and the predefined target concentrate production rate may be state-specific. In some embodiments, the controller may analyze the data signal on a predetermined basis. In some embodiments, the concentrate level may be assigned a predefined expected range, and the first threshold may be less than or equal to 50% of the maximum level of the expected range. In some embodiments, the first threshold may be 40% to 50% of the maximum level of the expected range. In some embodiments, the concentrate level may be assigned a predefined expected range, and the second threshold may be greater than or equal to 50% of the maximum level of the expected range. In some embodiments, the second threshold may be 50% to 60% of the maximum level of the expected range. In some embodiments, the concentrate level may be assigned a predefined expected range, and the first threshold may be less than or equal to 40% of the maximum level of the expected range. In some embodiments, the first threshold may be 40% to 30% of the maximum level of the expected range. In some embodiments, the concentrate level may be assigned a predefined expected range, and the second threshold may be greater than or equal to 45% of the maximum level of the expected range. In some embodiments, the second threshold may be 45% to 55% of the maximum level of the expected range. In some embodiments, the concentrate level may be assigned a predefined expected range, and the first and second thresholds may be defined as percentages of the maximum level of the expected range. The second threshold may be 4 to 20 percentage points above the first threshold. In some embodiments, the concentrate destination is a mixing tank.

[0015] According to another embodiment of the present disclosure, a method for controlling a concentrate level in a distillation device and regulating fluid flow within the distillation device may include inputting a source fluid into the distillation device through at least one inlet valve. The method may further include evaporating at least a portion of the source fluid as the source fluid travels toward a vapor chamber to generate vapor and concentrate. The method may further include collecting the concentrate in a concentrate reservoir attached to and positioned laterally relative to the vapor chamber via an inlet path. The method may further include providing a data signal indicative of the concentrate level in the steam chamber from a concentrate level sensor positioned within the concentrate reservoir. The method may further include using a controller to regulate operation of the at least one inlet valve via a fluid input control loop, analyze the data signal, and modify the concentrate level in a predetermined pattern by operating an outlet valve of the concentrate reservoir to a closed state when the data signal indicative of the concentrate level is below a first threshold and to an open state when the concentrate level is above a second threshold.

[0016] In some embodiments, modifying the concentrate level may include modifying the concentrate level to produce a sawtooth waveform when the concentrate level is plotted over time. In some embodiments, analyzing the data signal may include analyzing the data signal on a predetermined basis. In some embodiments, the method may further include assigning a predefined expected range to the concentrate level and setting a first threshold to be less than or equal to 50% of the maximum level of the expected range. In some embodiments, setting the first threshold may include setting the threshold to 40% to 50% of the maximum level of the expected range. In some embodiments, the method may further include assigning a predefined expected range to the concentrate level and setting a second threshold to be greater than or equal to 50% of the maximum level of the expected range. In some embodiments, setting the second threshold includes setting the second threshold to 50% to 60% of the maximum level of the expected range. In some embodiments, the method may further include assigning a predefined expected range to the concentrate level and setting the first threshold to be less than or equal to 40% of the maximum level of the expected range. In some embodiments, setting the first threshold may include setting the threshold between 40% and 30% of a maximum level of an expected range. In some embodiments, the method may further include assigning a predefined expected range of concentrate levels and setting the second threshold to be greater than or equal to 45% of a maximum level of the expected range. In some embodiments, setting the second threshold includes setting the second threshold to be between 45% and 55% of a maximum level of the expected range. In some embodiments, the method may further include assigning a predefined expected range of concentrate levels and setting the first and second thresholds as percentages of a maximum level of the expected range, the second threshold being 4 to 20 percentage points above the first threshold.

[0017] According to another embodiment of the present disclosure, a temperature control system for controlling the temperature of a product process stream of a distillation device to a required temperature may include a source fluid input in selective fluid communication with a source fluid reservoir via a set of fluid input valves. The system may further include an evaporator in fluid communication with the source input and in fluid communication with a compressor. The evaporator may be configured to convert source fluid from the source fluid input into a vapor stream and a condensate stream as the source fluid travels toward the compressor. The system may further include a condenser in fluid communication with the compressor, configured to convert pressurized vapor from the compressor into a condensate. The system may further include a condensate flow path and a condensate flow path, each including separate first and second heat exchangers. The first and second heat exchangers may each include a heat exchange portion of the source fluid flow path from the source fluid reservoir. The heat exchange portion may be downstream of the source fluid input valve. The system may further include a condensate temperature sensor configured to generate a data signal indicative of the condensate temperature. A condensate temperature sensor may be positioned in the condensate flow path downstream of the first heat exchanger. The system may further include a controller configured to operate the set of input source valves based on a first control loop that governs the total open time for all of the input source valves of the set of input source valves and a second control loop that receives the data signal and the desired temperature, divides the total open time among all of the input source valves, and adjusts the condensate temperature to the desired temperature.

[0018] In some embodiments, the heat exchange portions of the source fluid flow path within the first and second heat exchangers may be arranged in countercurrent flow with respect to their respective condensate and concentrate flow paths. In some embodiments, the system may further include a destination device in fluid communication with the condensate flow path via a point-of-use valve. In some embodiments, the required temperature may be generated by the destination device. In some embodiments, the destination device may be a medical system. In some embodiments, the medical system may be configured to mix at least one dialysate solution. In some embodiments, the destination device may be a dialysis machine. In some embodiments, the destination device may be a hemodialysis machine. In some embodiments, at least one of the first and second control loops may be a PID control loop. In some embodiments, the gain of at least one of the terms of the PID control loop may be zero. In some embodiments, a feedforward term may be combined with the output of the second control loop. In some embodiments, the feedforward term may be based on an estimated division of the total open time. In some embodiments, the system may further include a concentrate level sensor configured to output a concentrate level data signal indicative of the concentrate level in the distillation device. The first control loop may be configured to receive the target concentrate level and the current concentrate level data signal as inputs to the first control loop. In some embodiments, the controller may be further configured to adjust the heater duty cycle based, at least in part, on the total open time for all of the input source valves of the set of input source valves. In some embodiments, the controller may be configured to increase the heater duty cycle when the open time for all of the input source valves of the set of input source valves is increased.

[0019] According to another embodiment of the present disclosure, a method for controlling the temperature of a product process stream of a distillation device to a required temperature may include regulating the flow of a source fluid input to the distillation device by operating a set of source fluid valves using a controller. The method may further include converting at least a portion of the source fluid input to vapor and condensate in an evaporator. The method may further include condensing the vapor to a condensate in a condenser. The method may further include removing at least a portion of the condensate and condensate from the distillation device through separate condensate and condensate flow paths. The method may further include exchanging heat between the source fluid flow and the condensate flow path in a first heat exchanger and exchanging heat between the source fluid flow and the condensate flow path in a second heat exchanger. The method may further include providing a condensate temperature data signal to the controller from a temperature sensor in the condensate flow path located downstream of the first heat exchanger. The method may further include, with the controller, determining a total open time for the set of fluid input valves between the set of fluid input valves based on a first control loop, and dividing the total open time between the set of fluid input valves based on a second control loop that receives the temperature data signal and the required temperature.

[0020] In some embodiments, the method may further include flowing the concentrate and concentrate through the concentrate and concentrate flow paths countercurrent to the flow of the source fluid. In some embodiments, the method may further include providing the concentrate to a destination device by activating a point-of-use valve downstream of the temperature sensor. In some embodiments, the required temperature may be generated by the destination device. In some embodiments, the destination device may be a medical system. In some embodiments, the method may further include mixing the dialysate using the concentrate. In some embodiments, the destination device may be a dialysis machine. In some embodiments, the destination device may be a hemodialysis machine. In some embodiments, at least one of the first and second control loops may be a PID control loop. In some embodiments, the method may further include setting at least one of the gains of the PID control loop to zero. In some embodiments, the method may further include combining a feedforward term with an output of the second control loop. In some embodiments, the method may further include determining the feedforward term based on an estimated division of the total open time. In some embodiments, the method further includes inputting a current concentrate level and a target concentrate level provided by the concentrate level sensor into the first control loop. In some embodiments, the method may further include adjusting a heater duty cycle based, at least in part, on a total open time for all of the input source valves of the set of input source valves. In some embodiments, adjusting the heater duty cycle may include increasing the heater duty cycle when the open time for all of the input source valves of the set of input source valves is increased.

[0021] According to another embodiment of the present disclosure, a temperature control system for controlling the temperature of a product process stream of a distillation device to a required temperature may include a first source fluid input and a second source fluid input in selective fluid communication with a source fluid reservoir via a first set of fluid input valves and a second set of fluid input valves, respectively. The system may further include an evaporator in fluid communication with the first and second source fluid inputs and in fluid communication with the compressor. The evaporator may have a heating element for converting source fluid from the first and second source fluid inputs into a vapor stream and a condensate stream as the source fluid travels toward the compressor. The system may further include a condenser in fluid communication with the compressor. The condenser may be configured to convert pressurized vapor from the compressor into a condensate. The system may further include a condensate flow path and a condensate flow path including separate first and second heat exchangers. The first and second heat exchangers may each comprise a heat exchange portion of a source fluid flow path from a source fluid reservoir, the heat exchange portion being downstream of the set of source fluid input valves. The system may further include a condensate temperature sensor configured to generate a data signal indicative of a condensate temperature. The condensate temperature sensor may be disposed on the condensate flow path downstream of the first heat exchanger. The system may further include a controller configured to operate the first set of input source valves based on a first control loop that regulates a total open time for all input source valves of the first set of input source valves and a second control loop that receives the data signal and a desired temperature, divides the total open time among all of the input source valves of the first set of input source valves, and adjusts the condensate temperature to the desired temperature. The controller may be configured to monitor at least one process variable and operate the second set of input source valves when one of the at least one process variable is outside a predefined threshold.

[0022] In some embodiments, the first set of fluid input valves may include at least one valve that is not included in the second set of fluid input valves. In some embodiments, one of the first and second source fluid inputs may be temperature controlled. In some embodiments, the second source fluid input may be temperature controlled. In some embodiments, the second source fluid input may be a hot fluid input. In some embodiments, the at least one process variable monitored by the controller may be a heating element duty cycle. In some embodiments, the at least one process variable monitored by the controller may be an output of the first control loop. In some embodiments, the at least one process variable may be a compressor speed. In some embodiments, the heat exchange portion of the source fluid flow path may be a common flow path for fluids from the first and second source fluid inputs.

[0023] According to another embodiment of the present disclosure, a temperature control system for controlling the temperature of a product process stream of a distillation device to a required temperature may include a source fluid input in selective fluid communication with a source fluid reservoir via a set of fluid input valves. The system may further include an evaporator in selective fluid communication with the source fluid input via a bypass valve and in fluid communication with a compressor. The evaporator may be configured to convert the source fluid from the source fluid input into a vapor stream and a condensate stream as the source fluid travels toward the compressor. The system may further include a condenser in fluid communication with the compressor configured to convert the pressurized vapor from the compressor into a condensate. The system may further include a condensate flow path and a condensate flow path including respective first and second heat exchangers. The first and second heat exchangers may each include a heat exchange portion of the source fluid flow path from the source fluid reservoir, the heat exchange portion being downstream of the source fluid input valve. The system may further include a condensate temperature sensor configured to generate a data signal indicative of the condensate temperature. The condensate temperature sensor may be positioned on the condensate flow path downstream of the first heat exchanger. The system may further include a controller configured to operate the set of input source valves based on a first control loop that governs the total open time for all of the input source valves of the set of input source valves and a second control loop that receives the data signal and the desired temperature, divides the total open time among all of the input source valves, and adjusts the condensate temperature to the desired temperature. The bypass valve may be disposed in the source fluid flow path downstream of the heat exchange portion of the source fluid flow path. The bypass valve may have a diversion valve state that directs fluid from the source reservoir to a drain destination. The controller may be configured to operate the bypass valve to the diversion valve state when the controller determines that at least one process variable is outside a predetermined threshold.

[0024] In some embodiments, the at least one process variable may be a relationship between the condensate temperature and the source fluid temperature provided by the source fluid temperature sensor. In some embodiments, the at least one process variable may be the source fluid temperature sensed by the source fluid temperature sensor. In some embodiments, the at least one process variable may be defined, at least in part, by the condensate temperature and the source fluid temperature sensed by the source fluid temperature sensor. In some embodiments, the controller may modify the duty cycle of at least one of the input source valves when the bypass valve is in a diversion valve state. In some embodiments, the controller may increase the duty cycle of at least one of the input source valves when the bypass valve is in a diversion valve state. In some embodiments, the controller may modify the duty cycle of at least one of the input source valves to 90-100% when the bypass valve is in a diversion valve state. In some embodiments, one of the at least one input source valves may be a valve controlling the flow of source fluid through a heat exchange portion of the first heat exchanger.

[0025] According to another embodiment of the present disclosure, a temperature control system for controlling the temperature of a product process stream of a distillation system to a required temperature may include a source fluid input in selective fluid communication with a source fluid reservoir via a set of fluid input valves. The system may further include a distillation device configured to generate a concentrate stream and a condensate stream. The system may further include a condensate flow path and a concentrate flow path including respective first and second heat exchangers. The first and second heat exchangers may each include a heat exchange portion of the source fluid flow path from the source fluid reservoir, the heat exchange portion being downstream of the source fluid input valve. The system may further include a condensate temperature sensor configured to generate a data signal indicative of a condensate temperature. The condensate temperature sensor may be located on the condensate flow path downstream of the first heat exchanger. The system may further include a point-of-use device in selective communication with the condensate flow path. The point-of-use device may have an outlet flow path for an output fluid generated by the point-of-use device. The output flow path may have a third heat exchanger including a heat exchange portion of a branch of the source fluid flow path. The system may further include a controller configured to actuate the set of input source valves based on first and second control loops governing flow of the source fluid through the heat exchange portions of the first and second heat exchangers and based on at least one process variable. The controller may actuate the branch valve in the branch of the source fluid flow path when the at least one process variable is outside a predetermined threshold.

[0026] In some embodiments, the at least one process variable may be a relationship between the condensate temperature and the source fluid temperature provided by the source fluid temperature sensor. In some embodiments, the at least one process variable may be the source fluid temperature sensed by the source fluid temperature sensor. In some embodiments, the at least one process variable may be defined, at least in part, by the condensate temperature and the source fluid temperature sensed by the source fluid temperature sensor. In some embodiments, the point-of-use device may be a medical device. In some embodiments, the point-of-use device is a dialysis machine. In some embodiments, the point-of-use device is a hemodialysis machine or a peritoneal dialysis machine. In some embodiments, the point-of-use device may be a dialysate mixing device. In some embodiments, a branch of the source fluid flow path may be positioned upstream of the heat exchange portion of the source fluid flow path within the first and second heat exchangers. In some embodiments, the output fluid may be dialysate waste.

[0027] According to another embodiment of the present disclosure, a condensate accumulation rate control system for controlling the rate of condensate accumulation in a distillation device may include a source fluid input in selective fluid communication with a source fluid reservoir via a set of fluid input valves. The system may further include an evaporator in fluid communication with the compressor, the evaporator having an impeller in fluid communication with the source input and operably coupled to an impeller motor. The evaporator may be configured to convert source fluid from the source fluid input into a vapor stream and a condensate stream as the source fluid travels toward the compressor. The system may further include a condenser in heat transfer relationship with multiple exterior surfaces of the evaporator. The condenser may be configured to condense a high-pressure vapor stream from the compressor by contacting the high-pressure vapor stream with the multiple exterior surfaces of the evaporator. The system may further include a condensate level sensor configured to sense a current level of condensate in the condenser. The system may further include at least one controller configured to regulate the rotational speed of the impeller by periodically generating an impeller motor command based on the last motor speed command, a motor speed target, and a speed command increment limit. The motor speed target may be calculated by a control loop that receives the current condensate level and the desired condensate level as control loop inputs.

[0028] In some embodiments, the speed command increment limit may be ≦10 rpm / sec. In some embodiments, the speed command increment limit may be ≦5 rpm / sec. In some embodiments, the controller may be configured to compare the impeller motor command to a minimum command speed threshold and a maximum command speed threshold, and adjust the impeller motor command to a modified impeller motor command equal to the minimum command speed threshold when the impeller motor command is below the minimum command speed threshold, and equal to the maximum command speed threshold when the impeller motor command is above the maximum command speed threshold. In some embodiments, the minimum command speed threshold is between 1,500 and 2,500 rpm. In some embodiments, the maximum command speed threshold is calculated each time a motor speed command is generated. In some embodiments, the maximum command speed threshold may be calculated based on at least one motor parameter. In some embodiments, the system may further include a motor temperature sensor configured to output a temperature data signal indicative of a temperature of the impeller motor and a power factor correction current monitoring circuit configured to output a PFC data signal indicative of a current power factor correction current, and a maximum command speed threshold is calculated based on the temperature data signal and the PFC data signal. In some embodiments, the maximum command speed is capped at a predetermined value. In some embodiments, the predetermined value may be between 4,500 and 6,500 rpm. In some embodiments, the predetermined value may be 5,000 rpm. In some embodiments, the predetermined value may be approximately 2.5 times greater than the minimum command speed threshold.

[0029] According to another embodiment of the present disclosure, a method for controlling the rate of condensate accumulation in a distillation device may include providing a source fluid input to the distillation device. The method may further include evaporating at least a portion of the source fluid input into a low-pressure vapor in an evaporator. The method may further include compressing the low-pressure steam into high-pressure steam via the impeller. The method may further include condensing the high-pressure steam into condensate in a condenser and transferring heat from the high-pressure steam to an evaporator. The method may further include providing a level of condensate in the condenser sensed by the condensate level sensor to a controller. The method may further include calculating, with the controller, a motor speed target based on the condensate level and the desired condensate level. The method may further include regulating the rotational speed of the impeller by periodically generating an impeller motor command based on the last motor speed command, the motor speed target, and a speed command increment limit, with the controller.

[0030] In some embodiments, the speed command increment limit is ≦10 rpm / sec. In some embodiments, the speed command increment limit is ≦5 rpm / sec. In some embodiments, the method may further include, using the controller, comparing the impeller motor command to a minimum command speed threshold and a maximum command speed threshold, and adjusting the impeller motor command to a modified impeller motor command equal to the minimum command speed threshold when the impeller motor command is below the minimum command speed threshold, and equal to the maximum command speed threshold when the impeller motor command is above the maximum command speed threshold. In some embodiments, the minimum command speed threshold may be between 1,500 and 2,500 rpm. In some embodiments, the minimum command speed threshold may be 2,000 rpm. In some embodiments, the method may further include calculating a maximum command speed threshold each time the motor speed command is generated. In some embodiments, calculating the maximum command speed threshold may include calculating the maximum command speed threshold based on at least one motor parameter. In some embodiments, the method may further include providing a temperature data signal indicative of the temperature of the motor from the motor temperature sensor to the controller and a power factor correction data signal indicative of a current power factor correction current from the monitoring circuit to the controller. In some embodiments, the method may further include calculating a maximum command speed threshold based on the temperature data signal and the power factor correction data signal. In some embodiments, the method may further include capping the maximum command speed threshold at a predetermined value. In some embodiments, the predetermined value may be between 4,500 and 6,500 rpm. In some embodiments, the predetermined value may be 5,000 rpm. In some embodiments, the predetermined value may be 2.5 times greater than or approximately equal to the minimum command speed threshold.

[0031] According to certain embodiments of the present disclosure, a fluid vapor distillation apparatus having first and second separable sections may include a source inlet in selective fluid communication with a fluid source via at least one valve. The apparatus may further include a water reservoir downstream of the source inlet. The apparatus may further include an evaporator having a plurality of tubes in fluid communication with the water reservoir. The apparatus may further include a vapor chamber coupled to the evaporator and in fluid communication with the compressor. The apparatus may further include a condenser in fluid communication with an outlet of the compressor. The condenser may surround the plurality of tubes. The apparatus may further include a support plate rotatably coupled to a pivot and attached to the first section. The apparatus may further include a housing coupled to the second section via at least one mount. The first and second sections may be held together via one or more fasteners in a first state and disconnected from each other in a second state in which the first section is rotatable about the pivot.

[0032] In some embodiments, at least one mount may be an isolation mount. In some embodiments, the first section may include a sump, an evaporator, and a condenser. In some embodiments, the second section may include a steam chamber and a condenser. In some embodiments, the pivot may include a biasing member. In some embodiments, the biasing member may be in a relaxed state when the first and second sections are in a first state and in a compressed state when the first and second sections are in a second state. In some embodiments, the biasing member may have a relaxed state and an energy stored state. The support plate may have a displacement path between a first position when the biasing member is in the relaxed state and a second position when the biasing member is in the energy stored state. In some embodiments, the displacement path may be a linear displacement path. In some embodiments, the displacement path may be parallel to an axis of the pivot. In some embodiments, the biasing member may be a gas spring.

[0033] According to another embodiment of the present disclosure, a distillation device may include a source fluid input selectively in fluid communication with a source fluid reservoir via a set of fluid input valves. The device may further include an evaporator in fluid communication with the source input and in fluid communication with the compressor. The evaporator may be configured to convert source fluid from the source fluid input into a vapor stream and a condensate stream as the source fluid travels toward the compressor. The device may further include a condenser in fluid communication with the compressor configured to convert pressurized vapor from the compressor into a condensate. The device may further include a condensate flow path and a condensate flow path including separate first and second heat exchangers. The first and second heat exchangers may each include a heat exchange portion of the source fluid flow path from the source fluid reservoir. The heat exchange portion may be downstream of the source fluid input valve. The device may further include a condensate temperature sensor configured to generate a data signal indicative of a condensate temperature. The condensate temperature sensor may be located on the condensate flow path downstream of the first heat exchanger. The device may further include a controller configured to operate the set of input source valves based on a first multi-modal control loop that generates a number of interim total open commands for all of the input source valves of the set. The controller may be configured to operate the set of input source valves based on a slider that generates a single total open command from the number of interim commands. The controller may be configured to operate the set of input source valves based on a second control loop that receives the data signal and a temperature setpoint, distributes the total open command among all of the input source valves, and adjusts the condensate temperature to the temperature setpoint.

[0034] In some embodiments, the heat exchange portions of the source fluid flow path within the first and second heat exchangers may be disposed in countercurrent flow with respect to their respective condensate and concentrate flow paths. In some embodiments, the controller may be configured to operate in multiple operating states, and the temperature setpoint may be state-dependent. In some embodiments, the device further includes a destination device in fluid communication with the condensate flow path via a point-of-use valve. In some embodiments, the destination device may be a medical system. In some embodiments, the medical system may be configured to mix at least one dialysate solution. In some embodiments, the destination device may be a dialysis machine. In some embodiments, the destination device may be a hemodialysis machine. In some embodiments, at least one of the first multimodal control loop and the second control loop may include a PID control loop. In some embodiments, the gain of at least one of the terms of the PID control loop may be zero. In some embodiments, the number of interim total open state commands may be regulated by the output of the at least one regulator control loop. In some embodiments, the distillation device may further include a water sump. The water sump may be intermediate the source input and the evaporator. One of the at least one regulator control loop may be configured to produce an output based on a target sump temperature and a current sump temperature measured by a sump temperature sensor configured to generate a data signal representative of the temperature of the fluid in the sump. In some embodiments, one of the at least one regulator control loop may be configured to produce an output based on a target steam temperature and a current steam temperature measured by a steam temperature sensor configured to generate a data signal representative of the temperature of the steam stream. In some embodiments, the device may further include a concentrate level sensor configured to output a concentrate level data signal indicative of the concentrate level in the distillation device. The controller may be configured to determine a current blowdown rate from the concentrate level data signal.The first multi-modal control loop may be configured to receive as inputs a target blowdown rate and a current blowdown rate data signal. In some embodiments, at least one of the interim total open state commands may be a first production temperature state command, and at least one of the interim total open state commands may be a second production temperature state command. In some embodiments, the device may further include an evaporator level sensor configured to output an evaporator data signal. The controller may be configured to generate at least one of the interim total open state commands based, at least in part, on the input of the target evaporator sensor level and the evaporator data signal. In some embodiments, the target evaporator sensor level and the evaporator data signal may be input to a derivative controller. In some embodiments, the derivative controller may be a PID controller with a D-term gain that exceeds the P and I terms by at least an order of magnitude.

[0035] According to another embodiment of the present disclosure, a water vapor distillation apparatus may include a water basin having a source fluid input. The apparatus may further include an evaporator having a first side in fluid communication with the source fluid input via the water basin and a second side in fluid communication with the steam chamber. The evaporator may be configured to convert source fluid from the source fluid input into low-pressure steam and a condensate. During operation, a non-uniform liquid level may exist within the evaporator. The apparatus may further include an evaporator reservoir disposed laterally relative to the evaporator and in fluid communication with it via the water basin. The evaporator reservoir may include a level sensor configured to monitor the level of the water column within the evaporator reservoir and generate a data signal indicative of the level of the water column. The apparatus may further include a compressor having a low-pressure steam inlet establishing fluid communication with the steam chamber and a high-pressure steam outlet establishing fluid communication with the condenser via a condenser inlet. The apparatus may further include a condenser in heat transfer relationship with multiple exterior surfaces of the evaporator. The condenser may be configured to condense the high-pressure vapor stream from the compressor by contacting the high-pressure vapor stream with a plurality of exterior surfaces of the evaporator. The condenser may include a condensing portion and a condensate accumulation portion. The apparatus may further include a processor configured, in part, to actuate a set of input source valves to the source fluid input based on the data signal.

[0036] In some embodiments, the level sensor may include a displaceable member displaceable over a displacement range that is less than the height of the evaporator reservoir. In some embodiments, the level sensor may include a displaceable member displaceable over a displacement range that extends from a first end portion of the evaporator reservoir to at least a midpoint of the evaporator reservoir. The displacement range may be a distance that is less than 70% of the height of the evaporator reservoir. In some embodiments, the first end may be an end of the evaporator reservoir that is distal most from the sump. In some embodiments, the evaporator reservoir may be in communication with the steam chest through a vent path extending from the first end portion of the evaporator reservoir. In some embodiments, the vent path may extend from the evaporator reservoir to a concentrate reservoir attached to and positioned laterally relative to the steam chest. In some embodiments, the height of the evaporator reservoir may exceed the height of the evaporator. In some embodiments, the processor may be configured to determine a total open time for the set of input source valves based, in part, on a target water column level and a current water column level determined via analysis of the data signal. In some embodiments, the processor may be configured to determine a total open time for the set of input source valves based, in part, on the output of a PID controller that receives as inputs the target water column level and the current water column level. In some embodiments, the gain for at least one of the P, I, and D terms of the PID controller may be zero. In some embodiments, the gain for the D term of the PID controller may exceed the gains for the P and I terms of the PID controller by at least one order of magnitude. In some embodiments, the gain for the D term of the PID controller may exceed the gains for the P and I terms of the PID controller by more than two orders of magnitude. In some embodiments, the processor may be configured to determine a total open time based, in part, on the target blowdown rate and the current blowdown rate as indicated from a blowdown level data signal produced by a blowdown level sensor in a blowdown reservoir attached to the steam chest.In some embodiments, the processor may be configured to determine a total open state command based, in part, on an output of at least one regulator control loop. In some embodiments, one of the at least one regulator control loop may be configured to produce an output based on a target sump temperature and a current sump temperature measured by a sump temperature sensor configured to generate a data signal representative of the temperature of the fluid in the sump. In some embodiments, one of the at least one regulator control loop may be configured to produce an output based on a target steam temperature and a current steam temperature measured by a steam temperature sensor configured to generate a data signal representative of the temperature of the steam flow. In some embodiments, the controller may be configured to modify the total open state command for the set of input source valves in response to a change in the water column level indicated by the data signal. In some embodiments, the controller may be configured to modify the total open state command for the set of input source valves in proportion to a rate of change of the water column as indicated by the data signal.

[0037] According to another embodiment of the present disclosure, a method for controlling the flow of a source fluid into a distillation device may include establishing a non-uniform liquid level in an evaporator of the distillation device. The method may further include sensing, using a first level sensor, a liquid column level in an evaporator reservoir in fluid communication with the evaporator and positioned at the same height as the evaporator. The method may further include sensing, using a second level sensor, a concentrate level in a concentrate reservoir in fluid communication with the evaporator. The method may further include generating, using a processor, a source inlet valve open time command based, at least in part, on the concentrate level and a target concentrate accumulation rate and a delta between the liquid column level and the target liquid column level. The method may further include commanding a number of source inlet valves to open based on the source inlet valve open time command.

[0038] In some embodiments, sensing the liquid column level may include displacing the displaceable member through a displacement range that is less than the height of the evaporator reservoir. In some embodiments, sensing the liquid column level may include displacing the displaceable member through a displacement range that extends from a first end portion of the evaporator reservoir to at least a midpoint of the evaporator reservoir. The displacement range may be a distance less than 70% of the height of the evaporator reservoir. In some embodiments, the first end may be an end of the evaporator reservoir that is distal most to the sump of the distillation device. In some embodiments, the method may further include venting air from the evaporator reservoir through a vent path into a vapor chamber of the distillation device disposed above the evaporator. In some embodiments, the vent path may extend from the evaporator reservoir to a concentrate reservoir attached to and laterally disposed relative to the vapor chamber. In some embodiments, generating a source inlet valve open time command may include inputting a delta to a PID controller. In some embodiments, a gain for at least one of the P, I, and D terms of the PID controller may be zero. In some embodiments, the gain for the D term of the PID controller may exceed the gain for the P and I terms of the PID controller by at least an order of magnitude. In some embodiments, the gain for the D term of the PID controller may exceed the gains for the P and I terms of the PID controller by more than two orders of magnitude. In some embodiments, generating a source inlet valve open time command may include determining a current concentrate accumulation rate from the concentrate level and calculating a delta between a target concentrate rate and the current concentrate accumulation rate. In some embodiments, generating a source inlet valve open time command may include generating an output for at least one regulator control loop. In some embodiments, the method may further include sensing a current sump temperature with a sump temperature sensor, and generating an output for the at least one regulator control loop includes producing an output based on the target sump temperature and the current sump temperature. In some embodiments, the method may further include sensing a temperature of the vapor stream in the distillation device with a steam temperature sensor. In some embodiments, generating an output for the at least one regulator controller may include producing an output based on the target vapor temperature and the current vapor temperature. In some embodiments, the method may further include modifying the source inlet valve open time command in response to a change in the liquid column level. In some embodiments, the method may further include modifying the source inlet valve open time command in proportion to the rate of change of the liquid column level.

[0039] According to another embodiment of the present disclosure, a fluid vapor distillation apparatus may include at least one controller. The apparatus may further include a source inlet in selective fluid communication with a fluid source via at least one valve. The apparatus may further include an evaporator in fluid communication with the source inlet. The apparatus may further include a steam chamber coupled to the evaporator and in fluid communication with the compressor. An exterior surface of the steam chamber may form a portion of an inlet flow path to the compressor and a portion of an outlet flow path to an outlet of the compressor. The apparatus may further include a concentrate reservoir. The concentrate reservoir may be attached to the steam chamber via an inlet path and positioned laterally relative to the steam chamber such that at least a portion of the concentrate reservoir is flush with the steam chamber. The apparatus may further include a condenser in fluid communication with the compressor outlet via a linear flow path. The linear flow path may include a condenser inlet fixedly attached to the sheet, the condenser inlet having a first surface defining a portion of the vapor chest and an opposing surface defining a portion of the condenser. The apparatus may further include a product process stream reservoir coupled to the condenser by the product reservoir inlet and positioned laterally relative to the condenser such that at least a portion of the product process stream reservoir is flush with the condenser.

[0040] In some embodiments, the inlet path may include an obstruction. In some embodiments, the obstruction may include a wall extending into the concentrate reservoir at an angle generally perpendicular to the inlet path. In some embodiments, the obstruction may extend into the concentrate reservoir and divide the concentrate reservoir into a first portion and a second shielding portion. In some embodiments, the obstruction may include at least one vent port. In some embodiments, the product reservoir inlet may be adjacent to the product accumulation surface of the condenser. In some embodiments, the compressor may be driven by a motor disposed in part within a receiving well recessed into the side of the steam chest. In some embodiments, the compressor may include an impeller extending laterally relative to the steam chest and rotating about an axis parallel to the longitudinal axis of the steam chest.

[0041] According to another embodiment of the present disclosure, a distillation device may include a source fluid input in selective fluid communication with a source via a set of fluid input valves. The device may further include an evaporator in fluid communication with the compressor, the evaporator having an impeller in fluid communication with the source input and operably coupled to the impeller motor. The evaporator may be configured to convert source fluid from the source fluid input into a vapor stream and a concentrate stream as the source fluid travels toward the compressor. The device may further include a condenser in heat transfer relationship with multiple exterior surfaces of the evaporator. The condenser may be configured to condense the high-pressure vapor stream from the compressor by contacting the high-pressure vapor stream with the multiple exterior surfaces of the evaporator. The device may further include a concentrate level sensor disposed above the evaporator, having an inlet path, and having a longitudinal axis extending alongside the evaporator, configured to sense a current level of concentrate in a concentrate reservoir. The device may further include at least one controller configured to regulate the rotational speed of the impeller in the cold distillate production state and the hot distillate production state by periodically generating impeller motor commands based on a cold distillate production nominal speed command in the cold distillate production state and a hot distillate production nominal speed command in the hot distillate production state, wherein the cold distillate production nominal speed command may be a motor speed command that is faster than the hot distillate production nominal speed command.

[0042] In some embodiments, an adjustment may be made to the impeller motor command based on a data signal from a concentrate level sensor indicating the level of concentrate in the concentrate reservoir. In some embodiments, the adjustment may be limited by an impeller motor command increment limit. In some embodiments, the impeller motor command increment limit may be ≦10 rpm / sec. In some embodiments, the impeller motor command increment limit may be ≦5 rpm / sec. In some embodiments, the impeller motor command may be decremented when the data signal indicates that the level of concentrate in the concentrate reservoir exceeds a first threshold. In some embodiments, the first threshold may be defined as the concentrate level when the concentrate reservoir is at a predefined fill value of 65-80%. In some embodiments, the impeller motor command may be held below a previously commanded impeller motor command value when the data signal indicates that the level of concentrate in the concentrate reservoir exceeds the first threshold. In some embodiments, the first threshold may be defined as the concentrate level when the concentrate reservoir is at a predefined fill value between 65 and 80%. In some embodiments, the impeller motor command may be incremented when the data signal indicates that the level of concentrate in the concentrate reservoir is above a second threshold. In some embodiments, the hot distillate production nominal speed command may be a calibration value defined during production. In some embodiments, the hot distillate production nominal speed command may be less than 80% of the cold distillate production nominal speed command and greater than 45% of the cold distillate production nominal speed command. In some embodiments, the cold distillate production nominal speed command may be 4,500 rpm. In some embodiments, the cold distillate production nominal speed command may be 5,000 rpm.

[0043] According to another embodiment of the present disclosure, a method for controlling a compressor of a distillation device may include opening at least one fluid input valve and delivering a source fluid from a fluid source into a sump of the distillation device. The method may further include converting the source fluid into a concentrate stream and a vapor stream in an evaporator. The method may further include using a processor to determine a state-specific compressor speed command. The compressor speed command may be based on a cold distillate production nominal speed command in a cold distillate production state and a hot distillate production nominal speed command in a hot distillate production state. The cold distillate production nominal speed command may be a motor speed command that is faster than the hot distillate production nominal speed command. The method may further include using a processor to generate a final command speed based on the compressor speed command. The method may further include using a processor to command rotation of a compressor impeller at the final command speed. The method may further include compressing a vapor stream through the compressor. The method may further include condensing the vapor stream into a condensate and transferring heat to the evaporator as the vapor stream condenses.

[0044] In some embodiments, the method may further include sensing a level of concentrate in a concentrate reservoir in fluid communication with the evaporator using a level sensor. In some embodiments, generating a final command speed may include determining an adjustment to the compressor speed command based on the level of concentrate. In some embodiments, determining the adjustment may include decrementing the compressor speed command when the level of concentrate exceeds a first threshold. In some embodiments, the first threshold may be defined as the concentrate level when the concentrate reservoir is at a predefined fill value between 65 and 80%. In some embodiments, determining the adjustment may include maintaining the final command speed at or below a previously commanded final command speed when the level of concentrate exceeds the first threshold. In some embodiments, determining the adjustment may include decrementing the compressor speed command when the level of concentrate exceeds a second threshold. In some embodiments, generating a final command speed may include determining an adjustment to the compressor speed command. In some embodiments, the adjustment may be limited by an increment limit. In some embodiments, the increment limit may be ≦10 rpm / sec. In some embodiments, the increment limit may be ≦5 rpm / sec. In some embodiments, the hot distillate production nominal speed command may be a calibration value defined during production. In some embodiments, the hot distillate production nominal speed command may be less than 80% of the cold distillate production nominal speed command and greater than 70% of the cold distillate production nominal speed command. In some embodiments, the cold distillate production nominal speed command may be 4,500 rpm.

[0045] According to another embodiment of the present disclosure, a distillation device may include a water basin in selective fluid communication with a source via a set of fluid input valves. The device may further include at least one heating element and at least one water basin temperature sensor within the water basin. The water basin temperature sensor may be configured to generate a water basin temperature data signal. The device may further include an evaporator having a first side in fluid communication with the water basin and a second side in fluid communication with a compressor having an impeller operably coupled to an impeller motor. The evaporator may be configured to convert source fluid from the source fluid input into a vapor stream and a condensate. The device may further include a condenser in heat transfer relationship with a plurality of exterior surfaces of the evaporator. The condenser may be configured to condense the high-pressure steam flow from the compressor by contacting the high-pressure steam flow with multiple exterior surfaces of the evaporator. The device may further include a concentrate level sensor configured to sense a current level of concentrate in a concentrate reservoir having an inlet path and a longitudinal axis extending alongside the evaporator, the concentrate level sensor being positioned above the evaporator. The device may further include a steam temperature sensor positioned in a flow path of the steam flow and configured to generate a steam temperature data signal. The device may further include at least one controller configured to determine a duty cycle command for the at least one heating element. The duty cycle command may be based, at least in part, on a target temperature of the steam flow, the steam temperature data signal, the sump temperature data signal, and a total source open command for the set of fluid input valves.

[0046] In some embodiments, the target temperature of the vapor stream may be 108°C. In some embodiments, the controller may be configured to adjust the duty cycle command to conform to at least one limit. In some embodiments, the limit may be a maximum power consumption limit. In some embodiments, the controller may be configured to adjust the duty cycle command based, at least in part, on a power consumption of the compressor. In some embodiments, the controller may be configured to calculate a limit on the duty cycle command by determining a power consumption of the compressor and subtracting the power consumption of the compressor from a predefined power value. In some embodiments, the predefined power value may be defined as a maximum total power for the system. In some embodiments, the duty cycle command may be limited to a predetermined maximum duty cycle. In some embodiments, the predetermined maximum duty cycle may be less than or equal to 90% duty cycle. In some embodiments, the target temperature of the vapor stream may be state-specific. In some embodiments, the target temperature in the low temperature distillate production state may be higher than the target temperature in the high temperature distillate production state. In some embodiments, the target temperature of the vapor stream in the first state may be 108°C, and the target temperature of the vapor stream in the second state may be 104°C. In some embodiments, the target temperature in the first state may be 4°C higher than the target temperature in the second state. In some embodiments, the target temperature in the first state may be at least 95% of the target temperature in the second state, but less than the target temperature in the second state. In some embodiments, the controller may be configured to determine a feedforward term used to determine the duty cycle command based on a total source open command for the set of fluid input valves and at least one thermodynamic property of the source fluid. In some embodiments, the thermodynamic property may be the specific heat of the source fluid. In some embodiments, the target temperature of the steam stream may be 111-112°C.

[0047] According to an embodiment of the present disclosure, a method for heating a fluid in a distillation device may include opening at least one fluid input valve and delivering a source fluid from a fluid source into a water sump of the distillation device. The method may further include sensing a sump temperature of the source fluid in the sump via a temperature sensor. The method may further include sensing a vapor temperature of a vapor stream generated from the source fluid. The method may further include comparing the vapor temperature to a target vapor temperature using a processor. The method may further include inputting a delta between the vapor temperature and the target vapor temperature into a first controller and generating a first controller output. The method may further include providing an input to a second controller and generating a second controller output based, at least in part, on the first controller output and the water sump temperature. The method may further include modifying the second controller output to a modified second controller output based on a total open time of the at least one fluid input valve. The method may further include commanding a duty cycle for a heating element in the sump based on the modified second controller output and the at least one limit.

[0048] In some embodiments, the target vapor temperature may be in the range of 108°C to 112°C. In some embodiments, the at least one limit may include a maximum power consumption limit. In some embodiments, the at least one limit may include a limit based, at least in part, on a power consumption of a compressor in the distillation device. In some embodiments, the method may further include determining a power consumption of the compressor and calculating the at least one limit by subtracting the power consumption of the compressor from a predefined power value. In some embodiments, the predefined power value may be defined as a maximum total power for the system. In some embodiments, the at least one limit may include a predefined maximum duty cycle limit. In some embodiments, the predefined maximum duty cycle may be less than or equal to 90% duty cycle. In some embodiments, the target vapor temperature of the vapor stream may be state-specific. In some embodiments, the target temperature in the low temperature distillate production state may be higher than the target temperature in the high temperature distillate production state. In some embodiments, the target temperature in the first state may be 4° C. higher than the target temperature in the second state. In some embodiments, the target temperature in the first state may be at least 95% of the target temperature in the second state, but less than the target temperature in the second state. In some embodiments, the second controller output to the modified second controller output may include determining a feedforward term based on a total source open command of the at least one fluid input valve and at least one thermodynamic property of the source fluid. In some embodiments, the thermodynamic property may be the specific heat of the source fluid.

[0049] According to certain embodiments of the present disclosure, a water distillation device may include a water reservoir in selective fluid communication with a fluid source via a set of source proportional valves. The device may further include an evaporator in fluid communication with the water reservoir. The device may further include a steam chamber coupled to the evaporator and in fluid communication with the compressor. The device may further include a concentrate reservoir attached to the steam chamber via an inlet path and having a concentrate level sensor configured to generate a concentrate level data signal indicative of the fill percentage of the concentrate reservoir. The concentrate reservoir may be coupled to a concentrate flow path. The device may further include a condenser coupled to an outlet of the compressor and in fluid communication with the condensate flow path. The device may further include first and second heat exchangers comprising heat exchange portions of a source fluid flow path from the fluid source. The heat exchange portion of the first heat exchanger may be in heat exchange relationship with the condensate flow path, and the heat exchange portion of the second heat exchanger may be in heat exchange relationship with the concentrate flow path. The heat exchange portion of the source fluid flow path may be downstream of the source proportional valve. The device may further include at least one distillate sensor in communication with the condensate flow path at a point downstream of the first heat exchanger. The device may further include a controller configured to determine a total open time of the source proportional valves based, at least in part, on the concentrate data signal and the target concentrate rate. The controller may be configured to allocate a percentage of the total open command to each of the source proportional valves based on the at least one distillate sensor data signal from the at least one distillate sensor.

[0050] In some embodiments, the condenser may include a condensing portion and a condensate accumulation portion. In some embodiments, the condenser may be in fluid communication with a condensate reservoir including a condensate level sensor configured to monitor the level of condensate in the condensate reservoir and generate a condensate data signal indicative of the fill percentage of the condensate reservoir. The condensate reservoir may be intermediate the condenser and the concentrate flow path. In some embodiments, the controller may be configured to maintain a target fill percentage of the condensate reservoir based on the output of a PID control loop that uses as inputs a target fill percentage and a delta between the target fill percentage and the current fill percentage as indicated by the condensate data signal. In some embodiments, the target fill percentage may be at least equal to 1 liter and less than 2 liters. In some embodiments, the condenser may be in fluid communication with a condensate reservoir including a condensate level sensor configured to monitor the level of condensate in the condensate reservoir and generate a condensate data signal indicative of the fill percentage of the condensate reservoir. The condensate reservoir is intermediate the condenser and the concentrate flow path. In some embodiments, the at least one distillate sensor may include a temperature sensor, and in some embodiments, the at least one distillate sensor data signal may be a temperature data signal indicative of the current condensate temperature after passing through the heat exchanger. In some embodiments, the controller may be configured to allocate a percentage of the total open command to each of the source proportional valves based on a control loop that uses a target condensate temperature and a current condensate temperature as inputs. In some embodiments, the target temperature may be at least 35°C but not more than 40°C. In some embodiments, the target temperature may be at least 20°C but not more than 30°C. In some embodiments, the target temperature may be at least 90°C but less than 100°C. In some embodiments, the distillation device may further include a fluid source temperature sensor that generates a data signal indicative of the temperature of the source fluid, and the target temperature may be determined by the controller based, in part, on the source temperature data signal. In some embodiments, the target temperature may be limited to a range of 20-25°C.

[0051] According to another embodiment of the present disclosure, a distillation system may include a distillation device in selective fluid communication with a fluid source via a set of source proportional valves. The distillation device may have a concentrate output coupled to a concentrate flow path and a condensate output coupled to a condensate flow path. The system may further include first and second heat exchangers, each comprising a heat exchange portion of a source fluid flow path from the fluid source downstream of the source proportional valve. The heat exchange portion of the first heat exchanger may be in heat exchange relationship with the condensate flow path, and the heat exchange portion of the second heat exchanger may be in heat exchange relationship with the concentrate flow path. There may be a dedicated source proportional valve for each heat exchanger. The system may further include a condensate sensor assembly in communication with the condensate flow path at a point downstream of the first heat exchanger. The system may further include a controller configured, in a first mode of operation, to shunt a commanded flow of source fluid from the fluid source between the source proportional valves based on a delta between a first target temperature and a current concentrate temperature received by the controller from the condensate sensor assembly. In a second operating mode, the controller may be configured to allocate the entire commanded flow to the source proportional valve dedicated to the second heat exchanger and open the source proportional valve dedicated to the first heat exchanger at a duty cycle that may be below a predefined limit.

[0052] In some embodiments, the predefined limit may be 5%. In some embodiments, the predefined limit may be 2%. In some embodiments, the predefined limit may be 0%. In some embodiments, the condensate sensor assembly may include redundant temperature sensors. In some embodiments, the first and second heat exchangers may be spirals formed by wrapping the heat exchangers around the exterior of the distillation device. In some embodiments, the first operating mode may be a low temperature distillate production state and the second operating mode may be a high temperature distillate production state. In some embodiments, the first target temperature is at least 35°C but may be no greater than 40°C. In some embodiments, the first target temperature may be at least 20°C but less than 25°C. In some embodiments, the controller may be configured, in the second operating mode, to open the source proportional valve dedicated to the first heat exchanger based on the second target temperature and the delta between the second target temperature and the current concentrate temperature. In some embodiments, the second target temperature may be at least 65°C higher than the first target temperature. In some embodiments, the second target temperature may be at least 50°C higher than the first target temperature. In some embodiments, the second target temperature may be greater than 95°C and less than 100°C. In some embodiments, the second target temperature may be 96°C. In some embodiments, the second target temperature may be at least twice the first target temperature. In some embodiments, the second target temperature may be at least 2.5 times the first target temperature. In some embodiments, the second target temperature may be at least 3.5 times the first target temperature. In some embodiments, the system may further include an evaporator level sensor disposed in the evaporator reservoir in fluid communication with the evaporator of the distillation device. The controller may be configured, in the second operating state, to determine the total flow command based, at least in part, on the evaporator level data signal indicating the level of the water column in the evaporator reservoir. In some embodiments, the first target temperature is at least 20°C but may be no greater than 30°C. In some embodiments, the first target temperature is 25°C.

[0053] According to another embodiment of the present disclosure, a method for controlling and allocating the flow of a source fluid into a distillation device may include sensing a concentrate level in a concentrate reservoir in fluid communication with an evaporator of the distillation device using a concentrate level sensor. The method may further include sensing the temperature of a product fluid produced by the distillation device at a point downstream of a product heat exchanger that places the product fluid in heat exchange relationship with the inlet source fluid. The method may further include determining, using a processor, a concentrate accumulation rate based on the concentrate level. The method may further include calculating, using a processor, a first delta between the concentrate accumulation rate and a first target concentrate accumulation rate and a second delta between the concentrate accumulation rate and a second target concentrate accumulation rate. The method may further include determining, using a processor, first and second interim open commands for the first and second source inlet proportional valves. The first interim open command may be based on the first delta, and the second interim open command may be based on the second delta. The method may further include, using a processor, calculating a final open command from the interim open time command. The method may further include, using a processor, dividing the final open command between the first source inlet proportional valve and the second inlet proportional valve in a first operating state. The first source inlet proportional valve may be coupled to a product heat exchanger. The dividing may be based on a delta between the target production temperature and the temperature of the product fluid. The method may further include, using a processor, allocating the entire final open command to the second source inlet proportional valve in a second operating state. The method may further include, using a processor, opening the first source inlet proportional valve at a duty cycle below a predefined limit via a command from the processor in the second operating state.

[0054] In some embodiments, the first target accumulation rate may exceed the second target accumulation rate. In some embodiments, calculating the final open state command may include inputting a first interim open state command and a second interim open state command into a slider. In some embodiments, calculating the final open state command may include generating a hybrid command from the first and second interim source open state commands. In some embodiments, calculating the final open state command may include determining a first state fraction and a second state fraction, multiplying the first interim open state command by the first state fraction, and multiplying the second interim open state command by the second state fraction. In some embodiments, calculating the final open state command may include adjusting the command from primarily the first interim open state command to primarily the second interim open state command during a transition between the first operating state and the second operating state. In some embodiments, calculating the final open state command may include adjusting the command from entirely the first interim open state command to entirely the second interim open state command during a transition between the first operating state and the second operating state. In some embodiments, the second operating state may be a hot distillate production state. In some embodiments, dividing may include determining an open command for the first source inlet proportional valve based on a delta between the target product temperature and the temperature of the product fluid, and determining an open command for the second source inlet proportional valve by subtracting the open command from the first source inlet proportional valve from the final open command. In some embodiments, the predefined limit may be a limit of less than 5%. In some embodiments, the predefined limit may be a limit of less than 2%. In some embodiments, the predefined limit may be 0%. In some embodiments, determining the second interim open command may further include sensing the level of a liquid column in an evaporator reservoir in fluid communication with the evaporator using an evaporator level sensor. The second interim open command may be based, in part, on the delta between the level of the liquid column and the target level of the liquid column. In some embodiments, the second interim open command may be based on a rate of change of the delta between the level of the liquid column and the target level of the liquid column.

[0055] According to certain embodiments of the present disclosure, a medical system may include at least one concentrate fluid. The system may further include a distillation device having an evaporator, a condenser, and a purified product water heat exchanger having a source fluid flow path and a purified product water flow path in a heat exchange relationship with each other. The system may further include a medical treatment device, which may include a treatment fluid preparation circuit in selective fluid communication with the purified product water flow path via a point-of-use valve. The medical treatment device may include a treatment device processor configured to command mixing of the at least one concentrate and purified water to generate a prescribed treatment fluid using the treatment fluid preparation circuit. The system may further include a communication link between the treatment device processor of the medical treatment device and the distillation device processor of the distillation device. The medical treatment device processor may be configured to transmit mode commands to the distillation device processor. The system may further include a sensor assembly in communication with the purified product water flow path. The system may further include a source valve intermediate the fluid source and the source fluid flow path. The distillation device processor may be configured to actuate the source valve based at least in part on the mode command and data from the sensor assembly.

[0056] In some embodiments, the sensor assembly may include at least one temperature sensor and at least one conductivity sensor. In some embodiments, the distillation device processor may be configured to operate the source valve based, at least in part, on the mode command and temperature data from the sensor assembly. In some embodiments, the distillation device processor may be configured to operate the source valve based, at least in part, on the mode command, data from the sensor assembly, and a target set point for the purified water. In some embodiments, the target set point may be a temperature set point. In some embodiments, the target set point may be determined by the distillation device processor based on the mode command. In some embodiments, the target set point may be based on a first mode command of the mode command, which may be in the range of 20-35°C, and the target set point may be based on a second mode command of the mode command, which may be above 90°C.

[0057] In some embodiments, the medical treatment device may be a dialysis machine. In some embodiments, the medical treatment device may be a hemodialysis device. In some embodiments, the treatment fluid may be dialysis fluid. In some embodiments, the condenser may include a condensation section and a product storage section. The product storage section may have a volume of at least 1 liter. In some embodiments, the distillation device processor may be further configured to regulate operation of a compressor motor of the distillation device based, at least in part, on the mode command. In some embodiments, the distillation device processor may be further configured to regulate operation of a concentrate outlet valve of the distillation device based, at least in part, on the mode command.

[0058] According to an embodiment of the present disclosure, a medical system may include a distillation device having an evaporator, a source input flow path to a source inlet in fluid communication with the evaporator, a condenser, and a purified product water output flow path in fluid communication with the condenser. The system may further include first and second filters in the source inlet flow path. The system may further include a plurality of pressure sensors, including a first pressure sensor upstream of the first filter and a second pressure sensor downstream of the second filter. The system may further include a medical treatment device including a treatment fluid preparation circuit in selective fluid communication with the purified product water output flow path via a point-of-use valve. The system may further include a communication link between a treatment device processor of the medical treatment device and a distillation device processor of the distillation device. The distillation device processor may be configured to perform a first filter replacement check based on data from the plurality of pressure sensors, and the treatment device processor may be configured to perform a second filter replacement check and, if either the first or second filter replacement check fails, command the distillation device processor via the communication link to enter a filter replacement mode.

[0059] In some embodiments, the second filter replacement check may include checking the number of days elapsed since installation of the first and second filters against a limit. In some embodiments, the medical treatment device may include a graphical user interface. In some embodiments, the second filter replacement check may include checking a user input on the graphical user interface against at least one predefined criterion. In some embodiments, the system may further include a sampling port disposed intermediate the first filter and the second filter, wherein the predefined criterion may be a water chemistry test strip criterion. In some embodiments, the water chemistry test strip criterion may be a chlorination level criterion. In some embodiments, the distillation device processor may be configured to command cleaning of the first and second filters prior to at least one of the first filter replacement check or the second filter replacement check. In some embodiments, the distillation device processor may be configured to perform the first filter replacement check based on a filter output pressure data signal from the second pressure sensor. In some embodiments, the distillation device processor may be configured to indicate a failure of the first filter replacement check when the filter output pressure is below a threshold value. In some embodiments, the distillation device processor may be configured to perform a first filter replacement check based on a delta between the pressure upstream of the first and second filters as indicated by the first pressure sensor and the pressure downstream of the first and second filters as indicated by the second pressure sensor. In some embodiments, the distillation device processor may be configured to indicate a failure of the first filter replacement check when the delta is less than a threshold value.

[0060] According to another embodiment of the present disclosure, a medical system may include a distillation device having a source water input and a fluid output flow path. The system may further include a medical treatment device including a fluid inlet in selective fluid communication with the fluid output flow path via a plurality of fluid flow paths, a plurality of valves, at least one fluid pump, and a point-of-use valve. The system may further include a communication link between the medical treatment device and the distillation device. The system may further include a sensor assembly in communication with the fluid output flow path. The system may further include a treatment device processor configured to operate the plurality of valves and the at least one fluid pump to pump the high-temperature fluid through the plurality of fluid flow paths. The system may further include a distillation device processor configured to govern operation of the distillation device based on at least one data signal from the sensor assembly and mode commands transmitted from a treatment device processor of the medical treatment device via the communication link, and to produce and output a high temperature fluid to the fluid output flow path during a first cycle in which the distillation device processor commands the point-of-use valve to be open and a second cycle in which the distillation device processor commands the point-of-use valve to be closed and a valve to a flow path in fluid communication with the fluid output flow path to be open.

[0061] In some embodiments, the source water input may be in fluid communication with a non-temperature-controlled fluid source. In some embodiments, the medical treatment device may be a dialysis machine. In some embodiments, the medical treatment device may be a hemodialysis machine. In some embodiments, the multiple fluid flow paths may include a first flow path and a second flow path separated from each other by a semi-permeable membrane. In some embodiments, the multiple fluid flow paths may be included in at least a blood pumping cassette and a dialysate pumping cassette. In some embodiments, the medical treatment device may include a fluid reservoir, and the treatment device processor may be configured to send a signal to the distillation device processor to terminate the first cycle based on the amount of high-temperature fluid contained in the fluid reservoir. In some embodiments, the medical treatment device may include a heater. In some embodiments, the at least one data signal may include at least one temperature data signal. In some embodiments, the distillation device may include a compressor, and the distillation device processor may be configured to govern operation of the compressor via a compressor speed command determined in part based on the mode command. In some embodiments, the distillation device processor may be configured to govern operation of the distillation device to produce and output a medical treatment fluid component to a fluid output flow path based on at least one data signal and another mode command transmitted from the treatment device processor via the communication link. In some embodiments, the plurality of flow paths may comprise a medical treatment fluid mixing circuit, and the treatment device processor may be configured to command operation of at least one pump and a plurality of valves to mix the medical treatment fluid component with at least one concentrate in fluid communication with the plurality of flow paths according to a predetermined recipe.

[0062] According to another embodiment of the present disclosure, a water distillation apparatus may include a water reservoir having a source fluid input. The apparatus may further include an evaporator in fluid communication with the source fluid input via the water reservoir. The apparatus may further include a condenser including a condensation portion and a condensate accumulation portion. The apparatus may further include an auxiliary condensate reservoir in fluid communication with the condensate accumulation portion and attached to the condenser adjacent an accumulation surface of the accumulation portion. The auxiliary condensate reservoir may be fluidly coupled to a point-of-use device via a condensate flow path. The apparatus may further include a condensate level sensor configured to monitor the level of condensate in the accumulation portion and generate a data signal indicative of the fill level of the accumulation portion. The apparatus may further include a controller configured to govern operation of a diversion valve included in the condensate flow path based, at least in part, on the data signal and the target condensate level. The controller may further be configured to command the diversion valve to a closed state based on a derivative of the data signal.

[0063] In some embodiments, the accumulation portion may have a volume of less than 10 liters. In some embodiments, the condensate level sensor may include a float assembly mounted on a pivot. The float assembly may be displaceable about the pivot through a displacement range that includes points at heights that are the same as the range of fill levels in the accumulation portion. In some embodiments, the condensate level sensor may include a float displaceable along a displacement axis through a displacement range that includes points at heights that are the same as the range of fill levels in the accumulation portion. In some embodiments, the condensate level sensor may include a float displaceable along a displacement path through a displacement range that includes points at heights that are the same as the range of fill levels in the accumulation portion. In some embodiments, the controller may be configured to command the bypass valve to a closed state based on a derivative of the data signal exceeding a predefined minimum threshold. In some embodiments, the controller may be configured to command the bypass valve to a closed state based on a derivative of the data signal having a negative value that is greater than a predefined magnitude. In some embodiments, the controller may be configured to command the bypass valve to a closed state based on a derivative of the data signal indicating that the point-of-use device is consuming condensate from the distillation apparatus. In some embodiments, the apparatus may further include a heat exchanger including a portion of the condensate flow path and a portion of the source flow path coupled to the water source and the source fluid input. In some embodiments, the apparatus may further include a sensing assembly in communication with the condensate flow path downstream of the portion of the condensate flow path included in the heat exchanger. The sensing assembly may be configured to output a temperature data signal. In some embodiments, the controller may be configured to command the bypass valve to a closed state based on a derivative of the temperature data signal. In some embodiments, the controller may be configured to command the bypass valve to a closed state based on a derivative of the temperature data signal exceeding a predefined maximum threshold. In some embodiments, the controller may be configured to command the bypass valve to a closed state based on a derivative of the temperature data signal having a positive value greater than a predefined magnitude.In some embodiments, the controller may be configured to command the bypass valve to a closed state based on a derivative of the temperature data signal that indicates that the point-of-use device is consuming condensate from the distillation apparatus. In some embodiments, the controller may be configured to command the bypass valve to a closed state based on the integral of the derivative of the temperature data signal. In some embodiments, the controller may be configured to command the bypass valve to a closed state based on the integral of the derivative of the temperature data signal exceeding a predefined maximum threshold. In some embodiments, the controller may be configured to command the bypass valve to a closed state based on the integral of the derivative of the temperature data signal having a positive value above a predefined magnitude. In some embodiments, the controller may be configured to command the bypass valve to a closed state based on the integral of the derivative of the temperature data signal indicating that the point-of-use device is consuming condensate from the distillation apparatus.

[0064] According to another embodiment of the present disclosure, a water distillation apparatus may include a water reservoir having a source fluid input. The apparatus may further include an evaporator in fluid communication with the source fluid input via the water reservoir. The apparatus may further include a condenser fluidly coupled to a point-of-use device via a condensate flow path. The apparatus may further include a condensate level sensor configured to generate a data signal indicative of the fill level of the condenser. The apparatus may further include a heat exchanger including a portion of the condensate flow path and a portion of the source flow path coupled to the water source and the source fluid input. The apparatus may further include a sensing assembly in communication with the condensate flow path downstream of the portion of the condensate flow path included in the heat exchanger. The sensing assembly may be configured to output a sensor assembly data signal. The apparatus may further include a controller configured to govern operation of a diversion valve included in the condensate flow path based, at least in part, on the data signal and the target condensate level. The controller may further be configured to command the diversion valve to a closed state based on a derivative of the sensor assembly data signal.

[0065] In some embodiments, the controller may be configured to command the diversion valve to a closed state based on a derivative of the sensor assembly data signal. In some embodiments, the controller may be configured to command the diversion valve to a closed state based on a derivative of the sensor assembly data signal that exceeds a predefined maximum threshold. In some embodiments, the controller may be configured to command the diversion valve to a closed state based on a derivative of the sensor assembly data signal that has a positive value above a predefined magnitude. In some embodiments, the controller may be configured to command the diversion valve to a closed state based on a derivative of the sensor assembly data signal that indicates the point-of-use device is consuming condensate from the distillation apparatus. In some embodiments, the controller may be configured to command the diversion valve to a closed state based on an integral calculated using the sensor assembly data signal. In some embodiments, the integral may be calculated from the derivative of the sensor assembly data signal. In some embodiments, the controller may be configured to command the diversion valve to a closed state based on an integral that exceeds a predefined maximum threshold. In some embodiments, the controller may be configured to command the diversion valve to a closed state based on an integral that has a positive value above a predefined magnitude. In some embodiments, the controller may be configured to command the diversion valve to a closed state based on an integral that indicates the point-of-use device is consuming condensate from the distillation apparatus. In some embodiments, the sensor assembly data signal may be a temperature data signal.

[0066] According to another embodiment of the present disclosure, a water purification system for outputting a process stream at a controlled temperature may include a distillation device in selective fluid communication with a fluid source via a set of source proportional valves. The distillation device may have a concentrate output and a distillate output coupled to the concentrate flow path and the distillate flow path, respectively. The system may further include a first heat exchanger including a portion of the distillate flow path and a second heat exchanger including a portion of the concentrate flow path. The flow path from the fluid source may be in heat exchange relationship with each of the first and second heat exchangers. The system may further include a distillate sensor assembly in communication with the distillate flow path downstream of the portion of the distillate flow path contained within the first heat exchanger and configured to generate a distillate temperature measurement. The system may further include a controller configured to actuate the set of input source valves based on a first multi-modal control loop that generates a number of interim total open commands for the source proportional valves, a slider that generates a single total open command from the number of interim commands, and a second control loop that receives the distillate temperature measurement, the first target temperature, and the second target temperature, distribute the single total open command among all of the input source valves, and regulate the condensate temperature to a temperature setpoint.

[0067] In some embodiments, the system may further include an electronics box in thermal communication with the source fluid flow path. In some embodiments, the second control loop may generate interim allocation commands based at least in part on the first target temperature and the second target temperature and allocate the total open state command, at least in part, by inputting the interim allocation commands into a second slider. In some embodiments, the controller may be configured to operate in multiple operating states, and the temperature setpoint is state-dependent. In some embodiments, the controller may be configured to transition between a first state of the multiple operating states and a second state of the multiple operating states. In some embodiments, at least one of the first multi-modal control loop and the second control loop may include one or more PID control loops. In some embodiments, the one or more PID control loops may include a feedforward term that modifies the output of the one or more PID loops. In some embodiments, the number of interim total open state commands may be adjusted by the output of the at least one regulator control loop. In some embodiments, one of the at least one regulator control loop may be configured to produce an output based at least in part on the concentrate temperature. In some embodiments, the number of at least one of the interim total open state commands may be adjusted by a feedforward term. In some embodiments, at least one of the interim total open state commands may be modified based, at least in part, on a pre-allocated source duty cycle command determined based, at least in part, on a concentrate temperature sensed by a concentrate sensor assembly communicating with the concentrate flow path downstream of the portion of the concentrate flow path included in the second heat exchanger. In some embodiments, the second control loop may be configured to generate its output based, in part, on a target electronics temperature and a current electronics temperature measured by the electronics temperature sensor. In some embodiments, the temperature set point may be adjusted by the controller based, at least in part, on a source fluid temperature data signal generated by the source fluid temperature sensor.

[0068] According to another embodiment of the present disclosure, a water purification system for outputting a process stream at a controlled temperature may include a distillation device in selective fluid communication with a fluid source via a set of source proportional valves. The distillation device may have a concentrate output and a distillate output coupled to the concentrate flow path and the distillate flow path, respectively. The concentrate output may be disposed within a concentrate reservoir of the distillation device. The system may further include a first heat exchanger comprising a portion of the distillate flow path and a second heat exchanger comprising a portion of the concentrate flow path, the flow path from the fluid source being in a heat exchange relationship with each of the first and second heat exchangers. The system may further include a distillate sensor assembly in communication with the distillate flow path downstream of the portion of the distillate flow path contained within the first heat exchanger and configured to generate a distillate temperature measurement. The system may further include a concentrate level sensor disposed within the concentrate reservoir and configured to output a concentrate data signal. The system may further include a controller configured to determine a total open time of the source proportional valves based at least in part on the concentrate data signal, the target concentrate rate, and a minimum open time for at least one of the source proportional valves. The controller may be configured to allocate a percentage of the total open command to each of the source proportional valves based in part on the distillate temperature measurement and the minimum open time.

[0069] In some embodiments, the system may further include at least one source sensor in communication with the source fluid flow path. In some embodiments, the controller may be configured to allocate a percentage of the total open command to each of the source proportional valves based, in part, on a source sensor data signal. In some embodiments, the source sensor data signal may be a temperature data signal indicative of a current source fluid temperature. In some embodiments, the controller may be configured to allocate a percentage of the total open command to each of the source proportional valves based on a control loop that uses a target distillate temperature determined by the controller based on the current source fluid temperature. In some embodiments, the system may further include at least one concentrate temperature sensor in communication with the concentrate fluid flow path. In some embodiments, the controller may be configured to determine a total open time of the source proportional valves based, at least in part, on a concentrate temperature data signal generated by the at least one concentrate temperature sensor. In some embodiments, the controller may be configured to allocate a percentage of the total open command to each of the source proportional valves based on a control loop that uses a target concentrate temperature and the concentrate temperature data signal as inputs. In some embodiments, the controller may allocate a non-zero percentage of the total open command to at least one of the set of source constant ratio valves. In some embodiments, the controller may be configured to determine the total open time of the source constant ratio valves based, at least in part, on a feedforward term.

[0070] According to another embodiment of the present disclosure, a method for calibrating an operating speed setpoint of an impeller compressor disposed in a flow communication path between an evaporator and a condenser of a vapor compression distillation device, the impeller compressor for compressing a low-pressure stream generated in the evaporator into a high-pressure steam output to the condenser, may include driving impeller rotation to a first speed based on a target low-pressure steam temperature and a measured low-pressure steam temperature from a low-pressure steam temperature sensor. The method may further include performing a binary type search to determine the operating speed setpoint.

[0071] In some embodiments, performing a binary type search may include calculating a speed command based on the target low-pressure steam temperature and the measured low-pressure steam temperature. In some embodiments, performing a binary type search may include calculating a delta between the speed command and the starting speed and comparing the delta to a range. In some embodiments, performing a binary type search may include reducing the range and resetting the start speed when the delta is out of range. In some embodiments, performing a binary type search may include entering a stabilized state for a period of time before resetting the start speed. In some embodiments, performing a binary type search may include comparing a measured low-pressure steam temperature to a target low-pressure steam temperature. In some embodiments, performing a binary type search may include incrementing a timer when the measured low-pressure steam temperature relative to the target low-pressure steam temperature is within a predefined range of each other. In some embodiments, performing a binary type search may include saving the current speed command as an operating speed setpoint once the timer is incremented to a pre-determined value.

[0072] According to certain embodiments of the present disclosure, a fluid vapor distillation apparatus may include at least one controller and a source inlet in selective fluid communication with a fluid source via at least one valve. The fluid vapor distillation apparatus may further include an evaporator in fluid communication with the source inlet. The fluid vapor distillation apparatus may further include a vapor chest coupled to the evaporator and in fluid communication with the compressor. The fluid vapor distillation apparatus may further include a concentrate reservoir attached to the vapor chamber via an inlet path. The concentrate reservoir may be positioned laterally relative to the vapor chamber such that at least a portion of the concentrate reservoir is flush with the vapor chamber. The fluid vapor distillation apparatus may further include a condenser in fluid communication with the outlet of the compressor via a linear flow path. The linear flow path may include a condenser inlet having a fenestrated section with a plurality of fenestrations. The fenestrations may establish a flow path from the condenser inlet to the condenser. The fluid vapor distillation apparatus may further include a product process stream reservoir coupled to the condenser by a product reservoir inlet. The product process stream reservoir may be positioned laterally relative to the condenser such that at least a portion of the product process stream reservoir is flush with the condenser.

[0073] In some embodiments, the inlet path may include an obstruction. In some embodiments, the obstruction may include a plate. The plate may have a section extending into the concentrate reservoir at an angle generally perpendicular to the inlet path. In some embodiments, the obstruction may extend into the concentrate reservoir and divide the concentrate reservoir into a first portion and a second shielding portion. In some embodiments, the fluid steam distillation apparatus may further include a vent path extending from the concentrate reservoir to the steam chamber. In some embodiments, the vent path may extend generally parallel to and above the inlet path relative to gravity. In some embodiments, the product reservoir inlet may be adjacent to the product accumulation surface of the condenser. In some embodiments, the compressor may be driven by a motor mounted in a receiving well fitted into the side of the steam chamber. In some embodiments, the compressor may include an impeller passing through at least a portion of the steam chamber and rotating about an axis offset from but parallel to the longitudinal axis of the steam chamber.

[0074] According to another embodiment of the present disclosure, a water vapor distillation apparatus may include a water reservoir and an evaporator having a first side in fluid communication with the water reservoir. The evaporator may have a second side in fluid communication with the steam chamber. The water vapor distillation apparatus may further include a concentrate reservoir attached to the steam chamber via an inlet path having a first portion and a second portion. The second portion may be at least partially formed by an obstruction. The obstruction may extend transversely into the concentrate reservoir relative to the first portion and divide the concentrate reservoir into an unshielded section and a shielded section. The water vapor distillation apparatus may further include a float assembly disposed within the shielded section. The float assembly may be displaceable over a displacement range that includes a point at the same height as all steam chamber liquid levels within an expected range of steam chamber liquid levels. The water vapor distillation apparatus may further include a sensor configured to monitor the position of the float assembly and output a data signal indicative of the liquid level in the steam chamber based on the position of the float assembly. The water vapor distillation apparatus may further include a compressor having an inlet establishing fluid communication with the vapor chest and an outlet establishing fluid communication with the condenser.

[0075] In some embodiments, the sensor may be an encoder. In some embodiments, the float assembly may include at least one magnet. In some embodiments, the sensor may be a Hall Effect sensor. In some embodiments, the float assembly may be mounted on a pivot. In some embodiments, the float assembly may be displaceable about the pivot. In some embodiments, the obstruction may extend into the concentrate reservoir at an angle generally perpendicular to the first portion of the inflow path. In some embodiments, the water vapor distillation apparatus may further include a vent path extending from the concentrate reservoir to the steam chamber. In some embodiments, the vent path may extend parallel to and above the first portion of the inlet path. In some embodiments, the vent path may have a smaller cross-sectional area than the first portion of the inlet path.

[0076] According to another embodiment of the present disclosure, a water vapor distillation apparatus may include a water reservoir having a source fluid input. The water vapor distillation apparatus may further include an evaporator having a first side in fluid communication with the source fluid input via the water reservoir and a second side in fluid communication with the steam chamber. The evaporator may be configured to convert source fluid from the source fluid input into low-pressure steam and condensate as the source fluid travels toward the steam chamber. The water vapor distillation apparatus may further include a condensate reservoir attached to and positioned laterally relative to the steam chamber. The condensate reservoir may include a condensate level sensor configured to monitor the level of condensate in the steam chamber and generate a data signal indicative of the condensate level. The water vapor distillation apparatus may further include a compressor having a low-pressure steam inlet in fluid communication with the steam chamber and a high-pressure steam outlet in fluid communication with the condenser via the condenser inlet. The water vapor distillation apparatus may further include a condenser in heat transfer relationship with multiple exterior surfaces of the evaporator. The condenser may be configured to condense the high-pressure vapor stream from the compressor by contacting the high-pressure vapor stream with multiple exterior surfaces of the evaporator. The condenser may include a condensing portion and a condensate accumulation or storage portion. The water vapor distillation apparatus may further include an auxiliary condensate reservoir in fluid communication with the condensate accumulation portion. The auxiliary condensate reservoir may be attached to the condenser adjacent to an accumulation surface of the accumulation portion, and the auxiliary condensate reservoir may include a condensate level sensor configured to monitor the level of condensate in the accumulation portion and generate a data signal indicative of the percentage of the accumulation portion filled with condensate.

[0077] In some embodiments, the accumulation portion may have a volume of less than 10 liters. In some embodiments, the plurality of exterior surfaces may be exterior surfaces of a plurality of evaporator tubes contained within the evaporator. In some embodiments, the plurality of exterior surfaces may be exterior surfaces of 90 to 100 evaporator tubes contained within the evaporator. In some embodiments, the plurality of exterior surfaces may be exterior surfaces of 70 to 80 evaporator tubes contained within the evaporator. In some embodiments, the condensate level sensor may include a float assembly mounted on a pivot. In some embodiments, the float assembly may be displaceable about the pivot over a range of displacement that includes a point at the same height as the range of levels defined by the accumulation portion. In some embodiments, the concentrate level sensor may include a float assembly disposed within a shielded section of the concentrate reservoir separated from an unshielded portion of the concentrate reservoir by a barrier. In some embodiments, the float assembly may be mounted on a pivot and may be displaceable about the pivot over a range of displacement that includes a point at the same height as all steam chamber concentrate levels within the expected range of steam chamber liquid levels. In some embodiments, the concentrate level sensor may be disposed within a sleeve that forms the barrier.

[0078] According to another embodiment of the present disclosure, a concentrate level control system for a fluid vapor distillation apparatus may include a source fluid input in selective fluid communication with a source fluid reservoir via at least one input valve. The concentrate level control system may further include an evaporator in fluid communication with the source input and in fluid communication with a steam chamber. The evaporator may be configured to convert source fluid from the source fluid input into a vapor flow and a concentrate flow as the source fluid travels toward the steam chamber. The concentrate level control system may further include a concentrate reservoir attached to the steam chamber via an inlet path, disposed laterally therewith, and including an outlet in selective communication with a concentrate destination via an outlet valve. The concentrate level control system may further include a concentrate level sensor configured to generate a data signal indicative of the concentrate level in the steam chamber. The concentrate level control system may further include a controller configured to deliberately modify the concentrate level in a predetermined pattern by regulating operation of the at least one inlet valve via the fluid input control loop and analyzing the data signal. The controller may be further configured to actuate the outlet valve to a closed state when the data signal indicative of the concentrate level is below a first threshold, and to actuate the outlet valve to an open state when the concentrate level is above a second threshold.

[0079] In some embodiments, the predetermined pattern may produce a sawtooth waveform when the concentrate level is plotted over time. In some embodiments, the period of the sawtooth waveform may depend, at least in part, on the fluid input command from the fluid input control loop. In some embodiments, the fluid input command may be determined based on a pre-determined target concentrate production rate. In some embodiments, the controller may be configured to operate in multiple operating states, and the pre-defined target concentrate production rate may be state-specific. In some embodiments, the controller may analyze the data signal on a pre-defined basis. In some embodiments, the concentrate level may be assigned a pre-defined expected range, and the first threshold may be less than or equal to 50% of the maximum level of the expected range. In some embodiments, the first threshold may be 40% to 50% of the maximum level of the expected range. In some embodiments, the concentrate level may be assigned a pre-defined expected range, and the second threshold may be greater than or equal to 50% of the maximum level of the expected range. In some embodiments, the second threshold may be 50% to 60% of the maximum level of the expected range. In some embodiments, the concentrate level may be assigned a predefined expected range, and the first threshold may be less than or equal to 40% of the maximum level of the expected range. In some embodiments, the first threshold may be 40% to 30% of the maximum level of the expected range. In some embodiments, the concentrate level may be assigned a predefined expected range, and the second threshold may be greater than or equal to 45% of the maximum level of the expected range. In some embodiments, the second threshold may be 45% to 55% of the maximum level of the expected range. In some embodiments, the concentrate level may be assigned a predefined expected range, and the first and second thresholds may be defined as percentages of the maximum level of the expected range. The second threshold may be 4 to 20 percentage points above the first threshold. In some embodiments, the concentrate destination is a mixing tank.

[0080] According to another embodiment of the present disclosure, a method for controlling a concentrate level in a distillation device and regulating fluid flow within the distillation device may include inputting a source fluid into the distillation device through at least one inlet valve. The method may further include evaporating at least a portion of the source fluid as the source fluid travels toward a vapor chamber to generate vapor and concentrate. The method may further include collecting the concentrate in a concentrate reservoir attached to and positioned laterally relative to the vapor chamber via an inlet path. The method may further include providing a data signal indicative of the concentrate level in the steam chamber from a concentrate level sensor positioned within the concentrate reservoir. The method may further include using a controller to regulate operation of the at least one inlet valve via a fluid input control loop, analyze the data signal, and modify the concentrate level in a predetermined pattern by operating an outlet valve of the concentrate reservoir to a closed state when the data signal indicative of the concentrate level is below a first threshold and to an open state when the concentrate level is above a second threshold.

[0081] In some embodiments, modifying the concentrate level may include modifying the concentrate level to produce a sawtooth waveform when the concentrate level is plotted over time. In some embodiments, analyzing the data signal may include analyzing the data signal on a predetermined basis. In some embodiments, the method may further include assigning a predefined expected range to the concentrate level and setting a first threshold to be less than or equal to 50% of the maximum level of the expected range. In some embodiments, setting the first threshold may include setting the threshold to 40% to 50% of the maximum level of the expected range. In some embodiments, the method may further include assigning a predefined expected range to the concentrate level and setting a second threshold to be greater than or equal to 50% of the maximum level of the expected range. In some embodiments, setting the second threshold includes setting the second threshold to 50% to 60% of the maximum level of the expected range. In some embodiments, the method may further include assigning a predefined expected range to the concentrate level and setting the first threshold to be less than or equal to 40% of the maximum level of the expected range. In some embodiments, setting the first threshold may include setting the threshold between 40% and 30% of a maximum level of an expected range. In some embodiments, the method may further include assigning a predefined expected range of concentrate levels and setting the second threshold to be greater than or equal to 45% of a maximum level of the expected range. In some embodiments, setting the second threshold includes setting the second threshold to be between 45% and 55% of a maximum level of the expected range. In some embodiments, the method may further include assigning a predefined expected range of concentrate levels and setting the first and second thresholds as percentages of a maximum level of the expected range, the second threshold being 4 to 20 percentage points above the first threshold.

[0082] According to another embodiment of the present disclosure, a temperature control system for controlling the temperature of a product process stream of a distillation device to a required temperature may include a source fluid input in selective fluid communication with a source fluid reservoir via a set of fluid input valves. The system may further include an evaporator in fluid communication with the source input and in fluid communication with a compressor. The evaporator may be configured to convert source fluid from the source fluid input into a vapor stream and a condensate stream as the source fluid travels toward the compressor. The system may further include a condenser in fluid communication with the compressor, configured to convert pressurized vapor from the compressor into a condensate. The system may further include a condensate flow path and a condensate flow path, each including separate first and second heat exchangers. The first and second heat exchangers may each include a heat exchange portion of the source fluid flow path from the source fluid reservoir. The heat exchange portion may be downstream of the source fluid input valve. The system may further include a condensate temperature sensor configured to generate a data signal indicative of the condensate temperature. A condensate temperature sensor may be positioned in the condensate flow path downstream of the first heat exchanger. The system may further include a controller configured to operate the set of input source valves based on a first control loop that governs the total open time for all of the input source valves of the set of input source valves and a second control loop that receives the data signal and the desired temperature, divides the total open time among all of the input source valves, and adjusts the condensate temperature to the desired temperature.

[0083] In some embodiments, the heat exchange portions of the source fluid flow path within the first and second heat exchangers may be arranged in countercurrent flow with respect to their respective condensate and concentrate flow paths. In some embodiments, the system may further include a destination device in fluid communication with the condensate flow path via a point-of-use valve. In some embodiments, the required temperature may be generated by the destination device. In some embodiments, the destination device may be a medical system. In some embodiments, the medical system may be configured to mix at least one dialysate solution. In some embodiments, the destination device may be a dialysis machine. In some embodiments, the destination device may be a hemodialysis machine. In some embodiments, at least one of the first and second control loops may be a PID control loop. In some embodiments, the gain of at least one of the terms of the PID control loop may be zero. In some embodiments, a feedforward term may be combined with the output of the second control loop. In some embodiments, the feedforward term may be based on an estimated division of the total open time. In some embodiments, the system may further include a concentrate level sensor configured to output a concentrate level data signal indicative of the concentrate level in the distillation device. The first control loop may be configured to receive the target concentrate level and the current concentrate level data signal as inputs to the first control loop. In some embodiments, the controller may be further configured to adjust the heater duty cycle based, at least in part, on the total open time for all of the input source valves of the set of input source valves. In some embodiments, the controller may be configured to increase the heater duty cycle when the open time for all of the input source valves of the set of input source valves is increased.

[0084] According to another embodiment of the present disclosure, a method for controlling the temperature of a product process stream of a distillation device to a required temperature may include regulating the flow of a source fluid input to the distillation device by operating a set of source fluid valves using a controller. The method may further include converting at least a portion of the source fluid input to vapor and condensate in an evaporator. The method may further include condensing the vapor to a condensate in a condenser. The method may further include removing at least a portion of the condensate and condensate from the distillation device through separate condensate and condensate flow paths. The method may further include exchanging heat between the source fluid flow and the condensate flow path in a first heat exchanger and exchanging heat between the source fluid flow and the condensate flow path in a second heat exchanger. The method may further include providing a condensate temperature data signal to the controller from a temperature sensor in the condensate flow path located downstream of the first heat exchanger. The method may further include, with the controller, determining a total open time for the set of fluid input valves between the set of fluid input valves based on a first control loop, and dividing the total open time between the set of fluid input valves based on a second control loop that receives the temperature data signal and the required temperature.

[0085] In some embodiments, the method may further include flowing the concentrate and concentrate through the concentrate and concentrate flow paths countercurrent to the flow of the source fluid. In some embodiments, the method may further include providing the concentrate to a destination device by activating a point-of-use valve downstream of the temperature sensor. In some embodiments, the required temperature may be generated by the destination device. In some embodiments, the destination device may be a medical system. In some embodiments, the method may further include mixing the dialysate using the concentrate. In some embodiments, the destination device may be a dialysis machine. In some embodiments, the destination device may be a hemodialysis machine. In some embodiments, at least one of the first and second control loops may be a PID control loop. In some embodiments, the method may further include setting at least one of the gains of the PID control loop to zero. In some embodiments, the method may further include combining a feedforward term with an output of the second control loop. In some embodiments, the method may further include determining the feedforward term based on an estimated division of the total open time. In some embodiments, the method further includes inputting a current concentrate level and a target concentrate level provided by the concentrate level sensor into the first control loop. In some embodiments, the method may further include adjusting a heater duty cycle based, at least in part, on a total open time for all of the input source valves of the set of input source valves. In some embodiments, adjusting the heater duty cycle may include increasing the heater duty cycle when the open time for all of the input source valves of the set of input source valves is increased.

[0086] According to another embodiment of the present disclosure, a temperature control system for controlling the temperature of a product process stream of a distillation device to a required temperature may include a first source fluid input and a second source fluid input in selective fluid communication with a source fluid reservoir via a first set of fluid input valves and a second set of fluid input valves, respectively. The system may further include an evaporator in fluid communication with the first and second source fluid inputs and in fluid communication with the compressor. The evaporator may have a heating element for converting source fluid from the first and second source fluid inputs into a vapor stream and a condensate stream as the source fluid travels toward the compressor. The system may further include a condenser in fluid communication with the compressor. The condenser may be configured to convert pressurized vapor from the compressor into a condensate. The system may further include a condensate flow path and a condensate flow path including separate first and second heat exchangers. The first and second heat exchangers may each comprise a heat exchange portion of a source fluid flow path from a source fluid reservoir, the heat exchange portion being downstream of the set of source fluid input valves. The system may further include a condensate temperature sensor configured to generate a data signal indicative of a condensate temperature. The condensate temperature sensor may be disposed on the condensate flow path downstream of the first heat exchanger. The system may further include a controller configured to operate the first set of input source valves based on a first control loop that regulates a total open time for all input source valves of the first set of input source valves and a second control loop that receives the data signal and a desired temperature, divides the total open time among all of the input source valves of the first set of input source valves, and adjusts the condensate temperature to the desired temperature. The controller may be configured to monitor at least one process variable and operate the second set of input source valves when one of the at least one process variable is outside a predefined threshold.

[0087] In some embodiments, the first set of fluid input valves may include at least one valve that is not included in the second set of fluid input valves. In some embodiments, one of the first and second source fluid inputs may be temperature controlled. In some embodiments, the second source fluid input may be temperature controlled. In some embodiments, the second source fluid input may be a high temperature fluid input. In some embodiments, the at least one process variable monitored by the controller may be a heating element duty cycle. In some embodiments, the at least one process variable monitored by the controller may be an output of the first control loop. In some embodiments, the at least one process variable may be compressor speed. In some embodiments, the heat exchange portion of the source fluid flow path may be a common flow path for fluids from the first and second source fluid inputs.

[0088] According to another embodiment of the present disclosure, a temperature control system for controlling the temperature of a product process stream of a distillation device to a required temperature may include a source fluid input in selective fluid communication with a source fluid reservoir via a set of fluid input valves. The system may further include an evaporator in selective fluid communication with the source fluid input via a bypass valve and in fluid communication with a compressor. The evaporator may be configured to convert the source fluid from the source fluid input into a vapor stream and a condensate stream as the source fluid travels toward the compressor. The system may further include a condenser in fluid communication with the compressor configured to convert the pressurized vapor from the compressor into a condensate. The system may further include a condensate flow path and a condensate flow path including respective first and second heat exchangers. The first and second heat exchangers may each include a heat exchange portion of the source fluid flow path from the source fluid reservoir, the heat exchange portion being downstream of the source fluid input valve. The system may further include a condensate temperature sensor configured to generate a data signal indicative of the condensate temperature. The condensate temperature sensor may be positioned on the condensate flow path downstream of the first heat exchanger. The system may further include a controller configured to operate the set of input source valves based on a first control loop that governs the total open time for all of the input source valves of the set of input source valves and a second control loop that receives the data signal and the desired temperature, divides the total open time among all of the input source valves, and adjusts the condensate temperature to the desired temperature. The bypass valve may be disposed in the source fluid flow path upstream of the heat exchange portion of the source fluid flow path. The bypass valve may have a diversion valve state that directs fluid from the source reservoir to a drain destination. The controller may be configured to operate the bypass valve to the diversion valve state when the controller determines that at least one process variable is outside a predetermined threshold.

[0089] In some embodiments, the at least one process variable may be a relationship between the condensate temperature and the source fluid temperature provided by the source fluid temperature sensor. In some embodiments, the at least one process variable may be the source fluid temperature sensed by the source fluid temperature sensor. In some embodiments, the at least one process variable may be defined, at least in part, by the condensate temperature and the source fluid temperature sensed by the source fluid temperature sensor. In some embodiments, the controller may modify the duty cycle of at least one of the input source valves when the bypass valve is in a diversion valve state. In some embodiments, the controller may increase the duty cycle of at least one of the input source valves when the bypass valve is in a diversion valve state. In some embodiments, the controller may modify the duty cycle of at least one of the input source valves to 90-100% when the bypass valve is in a diversion valve state. In some embodiments, one of the at least one input source valves may be a valve controlling the flow of source fluid through a heat exchange portion of the first heat exchanger.

[0090] According to another embodiment of the present disclosure, a temperature control system for controlling the temperature of a product process stream of a distillation system to a required temperature may include a source fluid input in selective fluid communication with a source fluid reservoir via a set of fluid input valves. The system may further include a distillation device configured to generate a concentrate stream and a condensate stream. The system may further include a condensate flow path and a concentrate flow path including respective first and second heat exchangers. The first and second heat exchangers may each include a heat exchange portion of the source fluid flow path from the source fluid reservoir, the heat exchange portion being downstream of the source fluid input valve. The system may further include a condensate temperature sensor configured to generate a data signal indicative of a condensate temperature. The condensate temperature sensor may be located on the condensate flow path downstream of the first heat exchanger. The system may further include a point-of-use device in selective communication with the condensate flow path. The point-of-use device may have an outlet flow path for an output fluid generated by the point-of-use device. The output flow path may have a third heat exchanger including a heat exchange portion of a branch of the source fluid flow path. The system may further include a controller configured to actuate the set of input source valves based on first and second control loops governing flow of the source fluid through the heat exchange portions of the first and second heat exchangers and based on at least one process variable. The controller may actuate the branch valve in the branch of the source fluid flow path when the at least one process variable is outside a predetermined threshold.

[0091] In some embodiments, the at least one process variable may be a relationship between the condensate temperature and the source fluid temperature provided by the source fluid temperature sensor. In some embodiments, the at least one process variable may be the source fluid temperature sensed by the source fluid temperature sensor. In some embodiments, the at least one process variable may be defined, at least in part, by the condensate temperature and the source fluid temperature sensed by the source fluid temperature sensor. In some embodiments, the point-of-use device may be a medical device. In some embodiments, the point-of-use device is a dialysis machine. In some embodiments, the point-of-use device is a hemodialysis machine or a peritoneal dialysis machine. In some embodiments, the point-of-use device may be a dialysate mixing device. In some embodiments, a branch of the source fluid flow path may be positioned upstream of the heat exchange portion of the source fluid flow path within the first and second heat exchangers. In some embodiments, the output fluid may be dialysate waste.

[0092] According to another embodiment of the present disclosure, a condensate accumulation rate control system for controlling the rate of condensate accumulation in a distillation device may include a source fluid input in selective fluid communication with a source fluid reservoir via a set of fluid input valves. The system may further include an evaporator in fluid communication with the compressor, the evaporator having an impeller in fluid communication with the source input and operably coupled to an impeller motor. The evaporator may be configured to convert source fluid from the source fluid input into a vapor stream and a condensate stream as the source fluid travels toward the compressor. The system may further include a condenser in heat transfer relationship with multiple exterior surfaces of the evaporator. The condenser may be configured to condense a high-pressure vapor stream from the compressor by contacting the high-pressure vapor stream with the multiple exterior surfaces of the evaporator. The system may further include a condensate level sensor configured to sense a current level of condensate in the condenser. The system may further include at least one controller configured to regulate the rotational speed of the impeller by periodically generating an impeller motor command based on the last motor speed command, a motor speed target, and a speed command increment limit. The motor speed target may be calculated by a control loop that receives the current condensate level and the desired condensate level as control loop inputs.

[0093] In some embodiments, the speed command increment limit may be ≦10 rpm / sec. In some embodiments, the speed command increment limit may be ≦5 rpm / sec. In some embodiments, the controller may be configured to compare the impeller motor command to a minimum command speed threshold and a maximum command speed threshold, and adjust the impeller motor command to a modified impeller motor command equal to the minimum command speed threshold when the impeller motor command is below the minimum command speed threshold, and equal to the maximum command speed threshold when the impeller motor command is above the maximum command speed threshold. In some embodiments, the minimum command speed threshold is between 1,500 and 2,500 rpm. In some embodiments, the maximum command speed threshold is calculated each time a motor speed command is generated. In some embodiments, the maximum command speed threshold may be calculated based on at least one motor parameter. In some embodiments, the system may further include a motor temperature sensor configured to output a temperature data signal indicative of a temperature of the impeller motor and a power factor correction current monitoring circuit configured to output a PFC data signal indicative of a current power factor correction current, and a maximum command speed threshold is calculated based on the temperature data signal and the PFC data signal. In some embodiments, the maximum command speed is capped at a predetermined value. In some embodiments, the predetermined value may be between 4,500 and 6,500 rpm. In some embodiments, the predetermined value may be 5,000 rpm. In some embodiments, the predetermined value may be approximately 2.5 times greater than the minimum command speed threshold.

[0094] According to another embodiment of the present disclosure, a method for controlling the rate of condensate accumulation in a distillation device may include providing a source fluid input to the distillation device. The method may further include evaporating at least a portion of the source fluid input into a low-pressure vapor in an evaporator. The method may further include compressing the low-pressure steam into high-pressure steam via the impeller. The method may further include condensing the high-pressure steam into condensate in a condenser and transferring heat from the high-pressure steam to an evaporator. The method may further include providing a level of condensate in the condenser sensed by the condensate level sensor to a controller. The method may further include calculating, with the controller, a motor speed target based on the condensate level and the desired condensate level. The method may further include regulating the rotational speed of the impeller by periodically generating an impeller motor command based on the last motor speed command, the motor speed target, and a speed command increment limit, with the controller.

[0095] In some embodiments, the speed command increment limit is ≦10 rpm / sec. In some embodiments, the speed command increment limit is ≦5 rpm / sec. In some embodiments, the method may further include, using the controller, comparing the impeller motor command to a minimum command speed threshold and a maximum command speed threshold, and adjusting the impeller motor command to a modified impeller motor command equal to the minimum command speed threshold when the impeller motor command is below the minimum command speed threshold, and equal to the maximum command speed threshold when the impeller motor command is above the maximum command speed threshold. In some embodiments, the minimum command speed threshold may be between 1,500 and 2,500 rpm. In some embodiments, the minimum command speed threshold may be 2,000 rpm. In some embodiments, the method may further include calculating a maximum command speed threshold each time the motor speed command is generated. In some embodiments, calculating the maximum command speed threshold may include calculating the maximum command speed threshold based on at least one motor parameter. In some embodiments, the method may further include providing a temperature data signal indicative of the temperature of the motor from the motor temperature sensor to the controller and a power factor correction data signal indicative of a current power factor correction current from the monitoring circuit to the controller. In some embodiments, the method may further include calculating a maximum command speed threshold based on the temperature data signal and the power factor correction data signal. In some embodiments, the method may further include capping the maximum command speed threshold at a predetermined value. In some embodiments, the predetermined value may be between 4,500 and 6,500 rpm. In some embodiments, the predetermined value may be 5,000 rpm. In some embodiments, the predetermined value may be 2.5 times greater than or approximately equal to the minimum command speed threshold.

[0096] According to certain embodiments of the present disclosure, a fluid vapor distillation apparatus having first and second separable sections may include a source inlet in selective fluid communication with a fluid source via at least one valve. The apparatus may further include a water reservoir downstream of the source inlet. The apparatus may further include an evaporator having a plurality of tubes in fluid communication with the water reservoir. The apparatus may further include a vapor chamber coupled to the evaporator and in fluid communication with the compressor. The apparatus may further include a condenser in fluid communication with an outlet of the compressor. The condenser may surround the plurality of tubes. The apparatus may further include a support plate rotatably coupled to a pivot and attached to the first section. The apparatus may further include a housing coupled to the second section via at least one mount. The first and second sections may be held together via one or more fasteners in a first state and disconnected from each other in a second state in which the first section is rotatable about the pivot.

[0097] In some embodiments, at least one mount may be an isolation mount. In some embodiments, the first section may include a sump, an evaporator, and a condenser. In some embodiments, the second section may include a steam chamber and a condenser. In some embodiments, the pivot may include a biasing member. In some embodiments, the biasing member may be in a relaxed state when the first and second sections are in a first state and in a compressed state when the first and second sections are in a second state. In some embodiments, the biasing member may have a relaxed state and an energy stored state. The support plate may have a displacement path between a first position when the biasing member is in the relaxed state and a second position when the biasing member is in the energy stored state. In some embodiments, the displacement path may be a linear displacement path. In some embodiments, the displacement path may be parallel to an axis of the pivot. In some embodiments, the biasing member may be a gas spring.

[0098] According to another embodiment of the present disclosure, a distillation device may include a source fluid input selectively in fluid communication with a source fluid reservoir via a set of fluid input valves. The device may further include an evaporator in fluid communication with the source input and in fluid communication with the compressor. The evaporator may be configured to convert source fluid from the source fluid input into a vapor stream and a condensate stream as the source fluid travels toward the compressor. The device may further include a condenser in fluid communication with the compressor configured to convert pressurized vapor from the compressor into a condensate. The device may further include a condensate flow path and a condensate flow path including separate first and second heat exchangers. The first and second heat exchangers may each include a heat exchange portion of the source fluid flow path from the source fluid reservoir. The heat exchange portion may be downstream of the source fluid input valve. The device may further include a condensate temperature sensor configured to generate a data signal indicative of a condensate temperature. The condensate temperature sensor may be located on the condensate flow path downstream of the first heat exchanger. The device may further include an output to a destination device. The device may further include a controller configured to operate the set of input source valves based on a first multi-modal control loop that generates a number of interim total open commands for all of the input source valves of the set. The controller may be configured to operate the set of input source valves based on a slider that generates a single total open command from the number of interim commands. The controller may be configured to operate the set of input source valves based on a second control loop that receives the data signal and the desired temperature, distributes the total open command among all of the input source valves, and adjusts the condensate temperature to the temperature setpoint.

[0099] In some embodiments, the heat exchange portions of the source fluid flow path within the first and second heat exchangers may be disposed in countercurrent flow with respect to their respective condensate and concentrate flow paths. In some embodiments, the controller may be configured to operate in multiple operating states, and the temperature setpoint may be state-dependent. In some embodiments, the device further includes a destination device in fluid communication with the condensate flow path via a point-of-use valve. In some embodiments, the destination device may be a medical system. In some embodiments, the medical system may be configured to mix at least one dialysate solution. In some embodiments, the destination device may be a dialysis machine. In some embodiments, the destination device may be a hemodialysis machine. In some embodiments, at least one of the first multimodal control loop and the second control loop may include a PID control loop. In some embodiments, the gain of at least one of the terms of the PID control loop may be zero. In some embodiments, the number of interim total open state commands may be regulated by the output of the at least one regulator control loop. In some embodiments, the distillation device may further include a water sump. The water sump may be intermediate the source input and the evaporator. One of the at least one regulator control loop may be configured to produce an output based on a target sump temperature and a current sump temperature measured by a sump temperature sensor configured to generate a data signal representative of the temperature of the fluid in the sump. In some embodiments, one of the at least one regulator control loop may be configured to produce an output based on a target steam temperature and a current steam temperature measured by a steam temperature sensor configured to generate a data signal representative of the temperature of the steam stream. In some embodiments, the device may further include a concentrate level sensor configured to output a concentrate level data signal indicative of the concentrate level in the distillation device. The controller may be configured to determine a current blowdown rate from the concentrate level data signal.The first multi-modal control loop may be configured to receive as inputs a target blowdown rate and a current blowdown rate data signal. In some embodiments, at least one of the interim total open state commands may be a first production temperature state command, and at least one of the interim total open state commands may be a second production temperature state command. In some embodiments, the device may further include an evaporator level sensor configured to output an evaporator data signal. The controller may be configured to generate at least one of the interim total open state commands based, at least in part, on the input of the target evaporator sensor level and the evaporator data signal. In some embodiments, the target evaporator sensor level and the evaporator data signal may be input to a derivative controller. In some embodiments, the derivative controller may be a PID controller with a D-term gain that exceeds the P and I terms by at least an order of magnitude.

[0100] According to another embodiment of the present disclosure, a water vapor distillation apparatus may include a water basin having a source fluid input. The apparatus may further include an evaporator having a first side in fluid communication with the source fluid input via the water basin and a second side in fluid communication with the steam chamber. The evaporator may be configured to convert source fluid from the source fluid input into low-pressure steam and condensate as the source fluid travels toward the steam chamber. During operation, a non-uniform liquid level may exist within the evaporator. The apparatus may further include an evaporator reservoir disposed laterally relative to the evaporator and in fluid communication with it via the water basin. The evaporator reservoir may include a level sensor configured to monitor the level of a water column within the evaporator reservoir and generate a data signal indicative of the level of the water column. The apparatus may further include a compressor having a low-pressure steam inlet establishing fluid communication with the steam chamber and a high-pressure steam outlet establishing fluid communication with a condenser via a condenser inlet. The apparatus may further include a condenser in heat transfer relationship with multiple exterior surfaces of the evaporator. The condenser may be configured to condense the high-pressure vapor stream from the compressor by contacting the high-pressure vapor stream with a plurality of exterior surfaces of the evaporator. The condenser may include a condensing portion and a condensate accumulation portion. The apparatus may further include a processor configured, in part, to actuate a set of input source valves to the source fluid input based on the data signal.

[0101] In some embodiments, the level sensor may include a displaceable member displaceable over a displacement range that is less than the height of the evaporator reservoir. In some embodiments, the level sensor may include a displaceable member displaceable over a displacement range that extends from a first end portion of the evaporator reservoir to at least a midpoint of the evaporator reservoir. The displacement range may be a distance that is less than 70% of the height of the evaporator reservoir. In some embodiments, the first end may be an end of the evaporator reservoir that is distal most from the sump. In some embodiments, the evaporator reservoir may be in communication with the steam chest through a vent path extending from the first end portion of the evaporator reservoir. In some embodiments, the vent path may extend from the evaporator reservoir to a concentrate reservoir attached to and positioned laterally relative to the steam chest. In some embodiments, the height of the evaporator reservoir may exceed the height of the evaporator. In some embodiments, the processor may be configured to determine a total open time for the set of input source valves based, in part, on a target water column level and a current water column level determined via analysis of the data signal. In some embodiments, the processor may be configured to determine a total open time for the set of input source valves based, in part, on the output of a PID controller that receives as inputs the target water column level and the current water column level. In some embodiments, the gain for at least one of the P, I, and D terms of the PID controller may be zero. In some embodiments, the gain for the D term of the PID controller may exceed the gains for the P and I terms of the PID controller by at least one order of magnitude. In some embodiments, the gain for the D term of the PID controller may exceed the gains for the P and I terms of the PID controller by more than two orders of magnitude. In some embodiments, the processor may be configured to determine a total open time based, in part, on the target blowdown rate and the current blowdown rate as indicated from a blowdown level data signal produced by a blowdown level sensor in a blowdown reservoir attached to the steam chest.In some embodiments, the processor may be configured to determine a total open state command based, in part, on an output of at least one regulator control loop. In some embodiments, one of the at least one regulator control loop may be configured to produce an output based on a target sump temperature and a current sump temperature measured by a sump temperature sensor configured to generate a data signal representative of the temperature of the fluid in the sump. In some embodiments, one of the at least one regulator control loop may be configured to produce an output based on a target steam temperature and a current steam temperature measured by a steam temperature sensor configured to generate a data signal representative of the temperature of the steam flow. In some embodiments, the controller may be configured to modify the total open state command for the set of input source valves in response to a change in the water column level indicated by the data signal. In some embodiments, the controller may be configured to modify the total open state command for the set of input source valves in proportion to a rate of change of the water column as indicated by the data signal.

[0102] According to another embodiment of the present disclosure, a method for controlling the flow of a source fluid into a distillation device may include establishing a non-uniform liquid level in an evaporator of the distillation device by boiling liquid in the distillation device. The method may further include sensing, using a first level sensor, a liquid column level in an evaporator reservoir in fluid communication with the evaporator and positioned at the same height as the evaporator. The method may further include sensing, using a second level sensor, a concentrate level in a concentrate reservoir in fluid communication with the evaporator. The method may further include generating, using a processor, a source inlet valve open time command based, at least in part, on the concentrate level and a target concentrate accumulation rate and a delta between the liquid column level and the target liquid column level. The method may further include commanding a number of source inlet valves to open based on the source inlet valve open time command.

[0103] In some embodiments, sensing the liquid column level may include displacing the displaceable member through a displacement range that is less than the height of the evaporator reservoir. In some embodiments, sensing the liquid column level may include displacing the displaceable member through a displacement range that extends from a first end portion of the evaporator reservoir to at least a midpoint of the evaporator reservoir. The displacement range may be a distance less than 70% of the height of the evaporator reservoir. In some embodiments, the first end may be an end of the evaporator reservoir that is distal most to the sump of the distillation device. In some embodiments, the method may further include venting air from the evaporator reservoir through a vent path into a vapor chamber of the distillation device disposed above the evaporator. In some embodiments, the vent path may extend from the evaporator reservoir to a concentrate reservoir attached to and laterally disposed relative to the vapor chamber. In some embodiments, generating a source inlet valve open time command may include inputting a delta to a PID controller. In some embodiments, a gain for at least one of the P, I, and D terms of the PID controller may be zero. In some embodiments, the gain for the D term of the PID controller may exceed the gain for the P and I terms of the PID controller by at least an order of magnitude. In some embodiments, the gain for the D term of the PID controller may exceed the gains for the P and I terms of the PID controller by more than two orders of magnitude. In some embodiments, generating a source inlet valve open time command may include determining a current concentrate accumulation rate from the concentrate level and calculating a delta between a target concentrate rate and the current concentrate accumulation rate. In some embodiments, generating a source inlet valve open time command may include generating an output for at least one regulator control loop. In some embodiments, the method may further include sensing a current sump temperature with a sump temperature sensor, and generating an output for the at least one regulator control loop includes producing an output based on the target sump temperature and the current sump temperature. In some embodiments, the method may further include sensing a temperature of the vapor stream in the distillation device with a steam temperature sensor. In some embodiments, generating an output for the at least one regulator controller may include producing an output based on the target vapor temperature and the current vapor temperature. In some embodiments, the method may further include modifying the source inlet valve open time command in response to a change in the liquid column level. In some embodiments, the method may further include modifying the source inlet valve open time command in proportion to the rate of change of the liquid column level.

[0104] According to another embodiment of the present disclosure, a fluid vapor distillation apparatus may include at least one controller. The apparatus may further include a source inlet in selective fluid communication with a fluid source via at least one valve. The apparatus may further include an evaporator in fluid communication with the source inlet. The apparatus may further include a steam chamber coupled to the evaporator and in fluid communication with the compressor. An exterior surface of the steam chamber may form a portion of an inlet flow path to the compressor and a portion of an outlet flow path to an outlet of the compressor. The apparatus may further include a concentrate reservoir. The concentrate reservoir may be attached to the steam chamber via an inlet path and positioned laterally relative to the steam chamber such that at least a portion of the concentrate reservoir is flush with the steam chamber. The apparatus may further include a condenser in fluid communication with the compressor outlet via a linear flow path. The linear flow path may include a condenser inlet fixedly attached to the sheet, the condenser inlet having a first surface defining a portion of the vapor chest and an opposing surface defining a portion of the condenser. The apparatus may further include a product process stream reservoir coupled to the condenser by the product reservoir inlet and positioned laterally relative to the condenser such that at least a portion of the product process stream reservoir is flush with the condenser.

[0105] In some embodiments, the inlet path may include an obstruction. In some embodiments, the obstruction may include a wall extending into the concentrate reservoir at an angle generally perpendicular to the inlet path. In some embodiments, the obstruction may extend into the concentrate reservoir and divide the concentrate reservoir into a first portion and a second shielding portion. In some embodiments, the obstruction may include at least one vent port. In some embodiments, the product reservoir inlet may be adjacent to the product accumulation surface of the condenser. In some embodiments, the compressor may be driven by a motor disposed in part within a receiving well recessed into the side of the steam chest. In some embodiments, the compressor may include an impeller extending laterally relative to the steam chest and rotating about an axis parallel to the longitudinal axis of the steam chest.

[0106] According to another embodiment of the present disclosure, a distillation device may include a source fluid input in selective fluid communication with the source via a set of fluid input valves. The device may further include an evaporator in fluid communication with the source input and in fluid communication with the compressor, the evaporator having an impeller operably coupled to the impeller motor. The evaporator may be configured to convert source fluid from the source fluid input into a vapor stream and a concentrate stream as the source fluid travels toward the compressor. The device may further include a condenser in heat transfer relationship with the plurality of exterior surfaces of the evaporator. The condenser may be configured to condense the high-pressure vapor stream from the compressor by contacting the plurality of exterior surfaces of the evaporator with the high-pressure vapor stream. The device may further include a concentrate level sensor disposed above the evaporator, having an inlet path and a longitudinal axis extending alongside the evaporator, configured to sense a current level of concentrate in the concentrate reservoir. The device may further include at least one controller configured to regulate the rotational speed of the impeller in the cold distillate production state and the hot distillate production state by periodically generating an impeller motor command based on a cold distillate production nominal speed command in the cold distillate production state and a hot distillate production nominal speed command in the hot distillate production state. The cold distillate production nominal speed command may be a motor speed command that is faster than the hot distillate production nominal speed command.

[0107] In some embodiments, an adjustment may be made to the impeller motor command based on a data signal from a concentrate level sensor indicating the level of concentrate in the concentrate reservoir. In some embodiments, the adjustment may be limited by an impeller motor command increment limit. In some embodiments, the impeller motor command increment limit may be ≦10 rpm / sec. In some embodiments, the impeller motor command increment limit may be ≦5 rpm / sec. In some embodiments, the impeller motor command may be decremented when the data signal indicates that the level of concentrate in the concentrate reservoir exceeds a first threshold. In some embodiments, the first threshold may be defined as a concentrate level at which the concentrate reservoir is 65-80% full. In some embodiments, the impeller motor command may be held at or below a previously commanded impeller motor command value when the data signal indicates that the level of concentrate in the concentrate reservoir exceeds the first threshold. In some embodiments, the first threshold may be defined as a concentrate level at which the concentrate reservoir is 65-80% full. In some embodiments, the impeller motor command may be incremented when the data signal indicates that the level of concentrate in the concentrate reservoir is above a second threshold. In some embodiments, the hot distillate production nominal speed command may be a calibration value defined during production. In some embodiments, the hot distillate production nominal speed command may be less than 80% of the cold distillate production nominal speed command and greater than 70% of the cold distillate production nominal speed command. In some embodiments, the cold distillate production nominal speed command may be 4,500 rpm.

[0108] According to another embodiment of the present disclosure, a method for controlling a compressor of a distillation device may include opening at least one fluid input valve and delivering a source fluid from a fluid source into a sump of the distillation device. The method may further include converting the source fluid into a concentrate stream and a vapor stream in an evaporator. The method may further include using a processor to determine a state-specific compressor speed command. The compressor speed command may be based on a cold distillate production nominal speed command in a cold distillate production state and a hot distillate production nominal speed command in a hot distillate production state. The cold distillate production nominal speed command may be a motor speed command that is faster than the hot distillate production nominal speed command. The method may further include using a processor to generate a final command speed based on the compressor speed command. The method may further include using a processor to command rotation of a compressor impeller at the final command speed. The method may further include compressing a vapor stream through the compressor. The method may further include condensing the vapor stream into a condensate and transferring heat to the evaporator as the vapor stream condenses.

[0109] In some embodiments, the method may further include sensing a level of concentrate in a concentrate reservoir in fluid communication with the evaporator using a level sensor. In some embodiments, generating a final command speed may include determining an adjustment to the compressor speed command based on the level of concentrate. In some embodiments, determining the adjustment may include decrementing the compressor speed command when the concentrate level exceeds a first threshold. In some embodiments, the first threshold may be defined as a concentrate level where the concentrate reservoir is 65-80% full. In some embodiments, determining the adjustment may include maintaining the final command speed at or below a previously commanded final command speed when the concentrate level exceeds the first threshold. In some embodiments, determining the adjustment may include decrementing the compressor speed command when the concentrate level exceeds a second threshold. In some embodiments, generating a final command speed may include determining an adjustment to the compressor speed command. In some embodiments, the adjustment may be limited by an increment limit. In some embodiments, the increment limit may be ≦10 rpm / sec. In some embodiments, the increment limit may be ≦5 rpm / sec. In some embodiments, the hot distillate production nominal speed command may be a calibration value defined during production. In some embodiments, the hot distillate production nominal speed command may be less than 80% of the cold distillate production nominal speed command and greater than 70% of the cold distillate production nominal speed command. In some embodiments, the cold distillate production nominal speed command may be 4,500 rpm.

[0110] According to another embodiment of the present disclosure, the distillation device may include a water basin in selective fluid communication with the source via a set of fluid input valves. The device may further include at least one heating element and at least one water basin temperature sensor within the water basin. The water basin temperature sensor may be configured to generate a water basin temperature data signal. The device may further include an evaporator having a first side in fluid communication with the water basin and a second side in fluid communication with the compressor, the second side having an impeller operably coupled to the impeller motor. The evaporator may be configured to convert source fluid from the source fluid input into a vapor stream and a condensate as the source fluid travels toward the vapor chest. The device may further include a condenser in heat transfer relationship with the multiple exterior surfaces of the evaporator. The condenser may be configured to condense the high-pressure vapor stream from the compressor by contacting the high-pressure vapor stream with the multiple exterior surfaces of the evaporator. The device may further include a concentrate level sensor configured to sense a current level of concentrate in a concentrate reservoir having an inlet path and a longitudinal axis extending alongside the evaporator, the concentrate level sensor being positioned above the evaporator. The device may further include a steam temperature sensor positioned in a flow path of the steam flow and configured to generate a steam temperature data signal. The device may further include at least one controller configured to determine a duty cycle command for the at least one heating element. The duty cycle command may be based, at least in part, on a target temperature of the steam flow, the steam temperature data signal, the sump temperature data signal, and a total source open command for the set of fluid input valves.

[0111] In some embodiments, the target temperature of the vapor stream may be 108°C. In some embodiments, the controller may be configured to adjust the duty cycle command to conform to at least one limit. In some embodiments, the limit may be a maximum power consumption limit. In some embodiments, the controller may be configured to adjust the duty cycle command based, at least in part, on a power consumption of the compressor. In some embodiments, the controller may be configured to calculate a limit on the duty cycle command by determining a power consumption of the compressor and subtracting the power consumption of the compressor from a predefined power value. In some embodiments, the predefined power value may be defined as a maximum total power for the system. In some embodiments, the duty cycle command may be limited to a predetermined maximum duty cycle. In some embodiments, the predetermined maximum duty cycle may be less than or equal to 90% duty cycle. In some embodiments, the target temperature of the vapor stream may be state-specific. In some embodiments, the target temperature in the low temperature distillate production state may be higher than the target temperature in the high temperature distillate production state. In some embodiments, the target temperature of the vapor stream in the first state may be 108°C, and the target temperature of the vapor stream in the second state may be 104°C. In some embodiments, the target temperature in the first state may be 4°C higher than the target temperature in the second state. In some embodiments, the target temperature in the first state may be at least 95% of the target temperature in the second state, but less than the target temperature in the second state. In some embodiments, the controller may be configured to determine a feedforward term used to determine the duty cycle command based on a total source open command for the set of fluid input valves and at least one thermodynamic property of the source fluid. In some embodiments, the thermodynamic property may be the specific heat of the source fluid. In some embodiments, the target temperature of the steam stream may be 111-112°C.

[0112] According to an embodiment of the present disclosure, a method for heating a fluid in a distillation device may include opening at least one fluid input valve and delivering a source fluid from a fluid source into a water sump of the distillation device. The method may further include sensing a sump temperature of the source fluid in the sump via a temperature sensor. The method may further include sensing a vapor temperature of a vapor stream generated from the source fluid. The method may further include comparing the vapor temperature to a target vapor temperature using a processor. The method may further include inputting a delta between the vapor temperature and the target vapor temperature into a first controller and generating a first controller output. The method may further include providing an input to a second controller and generating a second controller output based, at least in part, on the first controller output and the water sump temperature. The method may further include modifying the second controller output to a modified second controller output based on a total open time of the at least one fluid input valve. The method may further include commanding a duty cycle for a heating element in the sump based on the modified second controller output and the at least one limit.

[0113] In some embodiments, the target vapor temperature may be in the range of 108°C to 112°C. In some embodiments, the at least one limit may include a maximum power consumption limit. In some embodiments, the at least one limit may include a limit based, at least in part, on a power consumption of a compressor in the distillation device. In some embodiments, the method may further include determining a power consumption of the compressor and calculating the at least one limit by subtracting the power consumption of the compressor from a predefined power value. In some embodiments, the predefined power value may be defined as a maximum total power for the system. In some embodiments, the at least one limit may include a predefined maximum duty cycle limit. In some embodiments, the predefined maximum duty cycle may be less than or equal to 90% duty cycle. In some embodiments, the target vapor temperature of the vapor stream may be state-specific. In some embodiments, the target temperature in the low temperature distillate production state may be higher than the target temperature in the high temperature distillate production state. In some embodiments, the target temperature in the first state may be 4° C. higher than the target temperature in the second state. In some embodiments, the target temperature in the first state may be at least 95% of the target temperature in the second state, but less than the target temperature in the second state. In some embodiments, the second controller output to the modified second controller output may include determining a feedforward term based on a total source open command of the at least one fluid input valve and at least one thermodynamic property of the source fluid. In some embodiments, the thermodynamic property may be the specific heat of the source fluid.

[0114] According to certain embodiments of the present disclosure, a water distillation device may include a water reservoir in selective fluid communication with a fluid source via a set of source proportional valves. The device may further include an evaporator in fluid communication with the water reservoir. The device may further include a steam chamber coupled to the evaporator and in fluid communication with the compressor. The device may further include a concentrate reservoir attached to the steam chamber via an inlet path and having a concentrate level sensor configured to generate a concentrate level data signal indicative of the fill percentage of the concentrate reservoir. The concentrate reservoir may be coupled to a concentrate flow path. The device may further include a condenser coupled to an outlet of the compressor and in fluid communication with the condensate flow path. The device may further include first and second heat exchangers comprising heat exchange portions of a source fluid flow path from the fluid source. The heat exchange portion of the first heat exchanger may be in heat exchange relationship with the condensate flow path, and the heat exchange portion of the second heat exchanger may be in heat exchange relationship with the concentrate flow path. The heat exchange portion of the source fluid flow path may be downstream of the source proportional valve. The device may further include at least one distillate sensor in communication with the condensate flow path at a point downstream of the first heat exchanger. The device may further include a controller configured to determine a total open time of the source proportional valves based, at least in part, on the concentrate data signal and the target concentrate rate. The controller may be configured to allocate a percentage of the total open command to each of the source proportional valves based on the at least one distillate sensor data signal from the at least one distillate sensor.

[0115] In some embodiments, the condenser may include a condensing portion and a condensate accumulation portion. In some embodiments, the condenser may be in fluid communication with a condensate reservoir including a condensate level sensor configured to monitor the level of condensate in the condensate reservoir and generate a condensate data signal indicative of the fill percentage of the condensate reservoir. The condensate reservoir may be intermediate the condenser and the concentrate flow path. In some embodiments, the controller may be configured to maintain a target fill percentage of the condensate reservoir based on the output of a PID control loop that uses as inputs a target fill percentage and a delta between the target fill percentage and the current fill percentage as indicated by the condensate data signal. In some embodiments, the target fill percentage may be at least equal to 1 liter and less than 2 liters. In some embodiments, the condenser may be in fluid communication with a condensate reservoir including a condensate level sensor configured to monitor the level of condensate in the condensate reservoir and generate a condensate data signal indicative of the fill percentage of the condensate reservoir. The condensate reservoir is intermediate the condenser and the concentrate flow path. In some embodiments, the at least one distillate sensor may include a temperature sensor, and in some embodiments, the at least one distillate sensor data signal may be a temperature data signal indicative of the current condensate temperature after passing through the heat exchanger. In some embodiments, the controller may be configured to allocate a percentage of the total open command to each of the source proportional valves based on a control loop that uses a target condensate temperature and a current condensate temperature as inputs. In some embodiments, the target temperature is at least 35° C. but may be no greater than 40° C. In some embodiments, the target temperature is at least 20° C. but may be no greater than 30° C.

[0116] According to another embodiment of the present disclosure, a distillation system may include a distillation device in selective fluid communication with a fluid source via a set of source proportional valves. The distillation device may have a concentrate output coupled to a concentrate flow path and a condensate output coupled to a condensate flow path. The system may further include first and second heat exchangers comprising heat exchange portions of a source fluid flow path from the fluid source downstream of the source proportional valve. The heat exchange portion of the first heat exchanger may be in heat exchange relationship with the condensate flow path, and the heat exchange portion of the second heat exchanger may be in heat exchange relationship with the concentrate flow path. There may be a dedicated source proportional valve for each heat exchanger. The system may further include a condensate sensor assembly in communication with the condensate flow path at a point downstream of the first heat exchanger. The system may further include a controller configured to, in a first operating state, divide a commanded flow of source fluid from the fluid source between the source proportional valves based on a first target temperature and a delta between the first target temperature and a current concentrate temperature received by the controller from the condensate sensor assembly. In a second operating mode, the controller may be configured to allocate the entire commanded flow to the source proportional valve dedicated to the second heat exchanger and open the source proportional valve dedicated to the first heat exchanger at a duty cycle that may be below a predefined limit.

[0117] In some embodiments, the predefined limit may be 5%. In some embodiments, the predefined limit may be 2%. In some embodiments, the condensate sensor assembly may include redundant temperature sensors. In some embodiments, the first and second heat exchangers may be spirals formed by wrapping the heat exchangers around the exterior of the distillation device. In some embodiments, the first operating state may be a low-temperature distillate production state, and the second operating state may be a high-temperature distillate production state. In some embodiments, the first target temperature may be at least 35°C but not more than 40°C. In some embodiments, the controller may be configured to open the source proportional valve dedicated to the first heat exchanger in the second operating state based on the second target temperature and the delta between the second target temperature and the current concentrate temperature. In some embodiments, the second target temperature may be at least 65°C higher than the first target temperature. In some embodiments, the second target temperature may be at least 50°C higher than the first target temperature. In some embodiments, the second target temperature may be greater than 95°C and less than 100°C. In some embodiments, the second target temperature may be 96°C. In some embodiments, the second target temperature may be at least twice the first target temperature. In some embodiments, the second target temperature may be at least 2.5 times the first target temperature. In some embodiments, the second target temperature may be at least 3.5 times the first target temperature. In some embodiments, the system may further include an evaporator level sensor disposed in an evaporator reservoir in fluid communication with the evaporator of the distillation device. The controller may be configured, in the second operating state, to determine the total flow command based, at least in part, on the evaporator level data signal indicating the level of the water column in the evaporator reservoir. In some embodiments, the first target temperature is at least 20°C but may be no greater than 30°C. In some embodiments, the first target temperature is 25°C.

[0118] According to another embodiment of the present disclosure, a method for controlling and allocating the flow of a source fluid into a distillation device may include sensing a concentrate level in a concentrate reservoir in fluid communication with an evaporator of the distillation device using a concentrate level sensor. The method may further include sensing the temperature of a product fluid produced by the distillation device at a point downstream of a product heat exchanger that places the product fluid in heat exchange relationship with the inlet source fluid. The method may further include determining, using a processor, a concentrate accumulation rate based on the concentrate level. The method may further include calculating, using a processor, a first delta between the concentrate accumulation rate and a first target concentrate accumulation rate and a second delta between the concentrate accumulation rate and a second target concentrate accumulation rate. The method may further include determining, using a processor, first and second interim open commands for the first and second source inlet proportional valves. The first interim open command may be based on the first delta, and the second interim open command may be based on the second delta. The method may further include, using a processor, calculating a final open command from the interim open time command. The method may further include, using a processor, dividing the final open command between the first source inlet proportional valve and the second inlet proportional valve in a first operating state. The first source inlet proportional valve may be coupled to a product heat exchanger. The dividing may be based on a delta between the target production temperature and the temperature of the product fluid. The method may further include, using a processor, allocating the entire final open command to the second source inlet proportional valve in a second operating state. The method may further include, using a processor, opening the first source inlet proportional valve at a duty cycle below a predefined limit via a command from the processor in the second operating state.

[0119] In some embodiments, the first target accumulation rate may exceed the second target accumulation rate. In some embodiments, calculating the final open state command may include inputting a first interim open state command and a second interim open state command into a slider. In some embodiments, calculating the final open state command may include generating a hybrid command from the first and second interim source open state commands. In some embodiments, calculating the final open state command may include determining a first state fraction and a second state fraction, multiplying the first interim open state command by the first state fraction, and multiplying the second interim open state command by the second state fraction. In some embodiments, calculating the final open state command may include adjusting the command from primarily the first interim open state command to primarily the second interim open state command during a transition between the first operating state and the second operating state. In some embodiments, calculating the final open state command may include adjusting the command from entirely the first interim open state command to entirely the second interim open state command during a transition between the first operating state and the second operating state. In some embodiments, the second operating state may be a hot distillate production state. In some embodiments, dividing may include determining an open command for the first source inlet proportional valve based on a delta between the target product temperature and the temperature of the product fluid, and determining an open command for the second source inlet proportional valve by subtracting the open command from the first source inlet proportional valve from the final open command. In some embodiments, the predefined limit may be a limit of less than 5%. In some embodiments, the predefined limit may be a limit of less than 2%. In some embodiments, determining the second interim open command may further include sensing the level of a liquid column in an evaporator reservoir in fluid communication with the evaporator using an evaporator level sensor. The second interim open command may be based, in part, on the delta between the level of the liquid column and the target level of the liquid column. In some embodiments, the second interim open command may be based on a rate of change of the delta between the level of the liquid column and the target level of the liquid column.

[0120] According to certain embodiments of the present disclosure, a medical system may include at least one concentrate fluid. The system may further include a distillation device having an evaporator, a condenser, and a purified product water heat exchanger having a source fluid flow path and a purified product water flow path in a heat exchange relationship with each other. The system may further include a medical treatment device, which may include a treatment fluid preparation circuit in selective fluid communication with the purified product water flow path via a point-of-use valve. The medical treatment device may include a treatment device processor configured to command mixing of the at least one concentrate and purified water to generate a prescribed treatment fluid using the treatment fluid preparation circuit. The system may further include a communication link between the treatment device processor of the medical treatment device and the distillation device processor of the distillation device. The medical treatment device processor may be configured to transmit mode commands to the distillation device processor. The system may further include a sensor assembly in communication with the purified product water flow path. The system may further include a source valve intermediate the fluid source and the source fluid flow path. The distillation device processor may be configured to actuate the source valve based at least in part on the mode command and data from the sensor assembly.

[0121] In some embodiments, the sensor assembly may include at least one temperature sensor and at least one conductivity sensor. In some embodiments, the distillation device processor may be configured to operate the source valve based, at least in part, on the mode command and temperature data from the sensor assembly. In some embodiments, the distillation device processor may be configured to operate the source valve based, at least in part, on the mode command, data from the sensor assembly, and a target set point for the purified water. In some embodiments, the target set point may be a temperature set point. In some embodiments, the target set point may be determined by the distillation device processor based on the mode command. In some embodiments, the target set point may be based on a first mode command of the mode command, which may be in the range of 20-30°C, and the target set point may be based on a second mode command of the mode command, which may be above 90°C.

[0122] In some embodiments, the medical treatment device may be a dialysis machine. In some embodiments, the medical treatment device may be a hemodialysis device. In some embodiments, the treatment fluid may be dialysis fluid. In some embodiments, the condenser may include a condensation section and a product storage section. The product storage section may have a volume of at least 1 liter. In some embodiments, the distillation device processor may be further configured to regulate operation of a compressor motor of the distillation device based, at least in part, on the mode command. In some embodiments, the distillation device processor may be further configured to regulate operation of a concentrate outlet valve of the distillation device based, at least in part, on the mode command.

[0123] According to an embodiment of the present disclosure, a medical system may include a distillation device having an evaporator, a source input flow path to a source inlet in fluid communication with the evaporator, a condenser, and a purified product water output flow path in fluid communication with the condenser. The system may further include first and second filters in the source inlet flow path. The system may further include a plurality of pressure sensors, including a first pressure sensor upstream of the first filter and a second pressure sensor downstream of the second filter. The system may further include a medical treatment device including a treatment fluid preparation circuit in selective fluid communication with the purified product water output flow path via a point-of-use valve. The system may further include a communication link between a treatment device processor of the medical treatment device and a distillation device processor of the distillation device. The distillation device processor may be configured to perform a first filter replacement check based on data from the plurality of pressure sensors, and the treatment device processor may be configured to perform a second filter replacement check and, if either the first or second filter replacement check fails, command the distillation device processor via the communication link to enter a filter replacement mode.

[0124] In some embodiments, the second filter replacement check may include checking the number of days elapsed since installation of the first and second filters against a limit. In some embodiments, the medical treatment device may include a graphical user interface. In some embodiments, the second filter replacement check may include checking a user input on the graphical user interface against at least one predefined criterion. In some embodiments, the system may further include a sampling port disposed intermediate the first filter and the second filter, wherein the predefined criterion may be a water chemistry test strip criterion. In some embodiments, the water chemistry test strip criterion may be a chlorination level criterion. In some embodiments, the distillation device processor may be configured to command cleaning of the first and second filters prior to at least one of the first filter replacement check or the second filter replacement check. In some embodiments, the distillation device processor may be configured to perform the first filter replacement check based on a filter output pressure data signal from the second pressure sensor. In some embodiments, the distillation device processor may be configured to indicate a failure of the first filter replacement check when the filter output pressure is below a threshold value. In some embodiments, the distillation device processor may be configured to perform a first filter replacement check based on a delta between the pressure upstream of the first and second filters as indicated by the first pressure sensor and the pressure downstream of the first and second filters as indicated by the second pressure sensor. In some embodiments, the distillation device processor may be configured to indicate a failure of the first filter replacement check when the delta is less than a threshold value.

[0125] According to another embodiment of the present disclosure, a medical system may include a distillation device having a source water input and a fluid output flow path. The system may further include a medical treatment device including a fluid inlet in selective fluid communication with the fluid output flow path via a plurality of fluid flow paths, a plurality of valves, at least one fluid pump, and a point-of-use valve. The system may further include a communication link between the medical treatment device and the distillation device. The system may further include a sensor assembly in communication with the fluid output flow path. The system may further include a treatment device processor configured to operate the plurality of valves and the at least one fluid pump to pump the high-temperature fluid through the plurality of fluid flow paths. The system may further include a distillation device processor configured to govern operation of the distillation device based on at least one data signal from the sensor assembly and mode commands transmitted from a treatment device processor of the medical treatment device via the communication link, and to produce and output a high temperature fluid to the fluid output flow path during a first cycle in which the distillation device processor commands the point-of-use valve to be open and a second cycle in which the distillation device processor commands the point-of-use valve to be closed and a valve to a flow path in fluid communication with the fluid output flow path to be open.

[0126] In some embodiments, the source water input may be in fluid communication with a non-temperature-controlled fluid source. In some embodiments, the medical treatment device may be a dialysis machine. In some embodiments, the medical treatment device may be a hemodialysis machine. In some embodiments, the multiple fluid flow paths may include a first flow path and a second flow path separated from each other by a semi-permeable membrane. In some embodiments, the multiple fluid flow paths may be included in at least a blood pumping cassette and a dialysate pumping cassette. In some embodiments, the medical treatment device may include a fluid reservoir, and the treatment device processor may be configured to send a signal to the distillation device processor to terminate the first cycle based on the amount of high-temperature fluid contained in the fluid reservoir. In some embodiments, the medical treatment device may include a heater. In some embodiments, the at least one data signal may include at least one temperature data signal. In some embodiments, the distillation device may include a compressor, and the distillation device processor may be configured to govern operation of the compressor via a compressor speed command determined in part based on the mode command. In some embodiments, the distillation device processor may be configured to govern operation of the distillation device to produce and output a medical treatment fluid component to a fluid output flow path based on at least one data signal and another mode command transmitted from the treatment device processor via the communication link. In some embodiments, the plurality of flow paths may comprise a medical treatment fluid mixing circuit, and the treatment device processor may be configured to command operation of at least one pump and a plurality of valves to mix the medical treatment fluid component with at least one concentrate in fluid communication with the plurality of flow paths according to a predetermined recipe.

[0127] The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features and advantages will be apparent from the description, drawings, and claims. The present specification also provides, for example, the following items: (Item 1) 1. A steam distillation system for providing a distillate at a controlled temperature, said steam distillation system comprising: a water vapor distillation device configured to receive a volume of source water from a fluid source and produce a distillate; The device comprises: a concentrate flow path having a concentrate output; a distillate flow path having a distillate output; at least one source constant ratio valve; a first heat exchanger comprising at least a portion of the distillate flow path; a second heat exchanger comprising at least a portion of the concentrate flow path, the first heat exchanger and the second heat exchanger being in fluid flow communication with the fluid source; a distillate sensor assembly in communication with the distillate flow path and located downstream of the first heat exchanger, the distillate sensor assembly configured to generate a distillate temperature measurement; a controller configured to control the source proportional valve; Equipped with The controller receiving the distillate temperature measurement; determining a difference between a first target temperature and the distillate temperature measurement; diverting source water from the fluid source between the first heat exchanger and the second heat exchanger based on a difference between the first target temperature and the measured distillate temperature; 1. A steam distillation system configured to: (Item 2) The controller further comprises: determining a total source proportional valve duty cycle; controlling a volume of source water received by the water vapor distillation device based on the total source proportional valve duty cycle; Item 1. The system according to item 1, configured to: (Item 3) The system further comprises: a concentrate reservoir; and Concentrate level sensor and Equipped with Item 3. The system of item 2, wherein the controller is configured to determine the total source proportional valve duty cycle based on a concentrate accumulation rate calculated from a level measurement output of the concentrate level sensor and a target concentrate accumulation rate. (Item 4) 3. The system of claim 2, wherein the controller is configured to allocate all of the total source proportional valve duty cycle to at least one source proportional valve that controls the flow of source water to the second heat exchanger in a second operating mode, and to control the at least one source proportional valve that controls the flow of source water to the first heat exchanger to open the at least one source proportional valve for an additional duty cycle that is not greater than a predefined limit. (Item 5) Item 5. The system of item 4, wherein the predefined limit is selected from the list consisting of 5%, 2%, less than 2%, and zero. (Item 6) 5. The system of claim 4, wherein the first operating mode is a low temperature distillate production state and the second operating mode is a high temperature distillate production state. (Item 7) Item 5. The system of item 4, wherein the controller is configured, in the second operating state, to open the at least one source proportional valve controlling the source water to the first heat exchanger based on a second target temperature and a difference between the second target temperature and the concentrate temperature. (Item 8) 8. The system of claim 7, wherein the second target temperature is at least 65° C. higher than the first target temperature. (Item 9) 8. The system of claim 7, wherein the second target temperature is at least 50° C. higher than the first target temperature. (Item 10) 8. The system of claim 7, wherein the second target temperature is greater than 95°C and less than 100°C. (Item 11) 8. The system of claim 7, wherein the second target temperature is 96°C. (Item 12) 8. The system of claim 7, wherein the second target temperature is at least twice the first target temperature. (Item 13) 8. The system of claim 7, wherein the second target temperature is at least 2.5 times the first target temperature. (Item 14) 8. The system of claim 7, wherein the second target temperature is at least 3.5 times the first target temperature. (Item 15) The water vapor distillation device further comprises: an evaporator; an evaporator reservoir in fluid communication with the evaporator; an evaporator level sensor disposed within the evaporator reservoir, the evaporator level sensor in communication with the controller, the evaporator level sensor transmitting a data signal to the controller providing a level of a water column within the evaporator reservoir; Equipped with Item 1. The system of item 1, wherein in the second mode, the controller is configured to determine the total source proportional valve duty cycle based, at least in part, on the evaporator level data signal indicative of the level of the water column in the evaporator reservoir. (Item 16) Item 10. The system of item 1, wherein the first target temperature is at least 20°C but not more than 25°C. (Item 17) Item 1. The system of item 1, further comprising a source fluid temperature sensor in communication with the controller, the source fluid temperature sensor providing the controller with data related to the source fluid temperature measurements, and the controller configured to determine the first target temperature based, at least in part, on the source fluid temperature measurements received from the source fluid temperature sensor. (Item 18) Item 10. The system of claim 1, further comprising a concentrate sensor assembly in communication with the concentrate flow path downstream of the portion of the concentrate flow path contained within the second heat exchanger and configured to generate a concentrate temperature measurement. (Item 19) Item 19. The system of item 18, wherein the controller is configured to open at least one source proportional valve controlling source water to the second heat exchanger based, at least in part, on a difference between a third target temperature and the measured concentrate temperature. (Item 20) 20. The system of claim 19, wherein the third target temperature is a historical average of the concentrate temperature. (Item 21) Item 10. The system of claim 1, wherein the controller is configured to open at least one source proportional valve controlling source water to the second heat exchanger based at least in part on a minimum limit. (Item 22) 22. The system of claim 21, wherein the minimum limit exceeds a predefined duty cycle or a predefined percentage of the combined duty cycle for all of the source proportional valves. (Item 23) Item 10. The system of item 1, wherein the controller is disposed in an electronics box in heat transfer relationship with a flow path from the source water leading to the second heat exchange. (Item 24) Item 24. The system of item 23, wherein the controller is configured to determine an electronics box cooling duty cycle command based at least in part on an electronics box cooling duty cycle command and to open at least one source proportional valve controlling source water to the second heat exchanger. (Item 25) Item 10. The system of claim 1, wherein the distillate sensor assembly includes redundant temperature sensors. (Item 26) Item 10. The system of claim 1, wherein the distillate sensor assembly comprises redundant temperature sensors and redundant conductivity sensors. (Item 27) Item 10. The system of claim 1, wherein the first and second heat exchangers are spirals formed by wrapping the heat exchangers around the exterior of the distillation device. (Item 28) 1. A fluid vapor distillation apparatus comprising: At least one controller; a source inlet in selective fluid communication with the fluid source via at least one valve; an evaporator in fluid communication with the source inlet; a vapor chest coupled to the evaporator and in fluid communication with a compressor; a concentrate reservoir attached to the steam chamber via an inlet passage and positioned laterally relative to the steam chamber such that at least a portion of the concentrate reservoir is at the same height as the steam chamber; a condenser in fluid communication with the compressor outlet via a linear flow path, the linear flow path including a condenser inlet having a fenestrated section with a plurality of fenestrations, the fenestrations establishing a flow path from the condenser inlet to the condenser; a product process stream reservoir coupled to the condenser by a product reservoir inlet and positioned laterally relative to the condenser such that at least a portion of the product process stream reservoir is flush with the condenser; An apparatus comprising: (Item 29) Item 29. The apparatus of item 28, wherein the inflow path includes an obstacle. (Item 30) 30. The apparatus of claim 29, wherein the obstacle comprises a plate having a compartment that extends into the concentrate reservoir at an angle generally perpendicular to the inlet path. (Item 31) 30. The apparatus of claim 29, wherein the obstruction extends into the concentrate reservoir and divides the concentrate reservoir into a first portion and a second shielded portion. (Item 31) Item 29. The device of item 28, further comprising an air vent passage extending from the concentrate reservoir to the steam chest, the air vent passage extending generally parallel to and above the inlet passage relative to gravity. (Item 32) Item 29. The apparatus of item 28, wherein the product reservoir inlet is adjacent to a product accumulation surface of the condenser. (Item 33) Item 29. The apparatus of item 28, wherein the compressor is driven by a motor mounted in a receiving well that fits into the side of the steam chest. (Item 34) Item 29. The apparatus of item 28, wherein the compressor includes an impeller that passes through at least a portion of the steam chest and rotates about an axis that is offset from but parallel to the longitudinal axis of the steam chest. (Item 35) 1. A fluid vapor distillation apparatus having first and second separable sections, comprising: a source inlet in selective fluid communication with the fluid source via at least one valve; a sump downstream of the source inlet; an evaporator having a plurality of tubes in fluid communication with the sump; a vapor chest coupled to the evaporator and in fluid communication with a compressor; a condenser in fluid communication with the compressor outlet, the condenser surrounding the plurality of tubes; a support plate rotatably coupled to a pivot and attached to the first section; a housing coupled to the second section via at least one mounting portion; and Equipped with The device wherein the first and second sections are held together via one or more fasteners in a first state and disconnected from one another in a second state, wherein the first section is rotatable about the pivot axis. (Item 36) Item 36. The apparatus of item 35, wherein the at least one mount is an isolation mount. (Item 37) Item 36. The apparatus of item 35, wherein the first section includes the sump, an evaporator, and a condenser. (Item 38) Item 36. The apparatus of item 35, wherein the second section includes the vapor chest and a condenser. (Item 39) Item 36. The device of item 35, wherein the pivot includes a biasing member. (Item 40) Item 40. The device of item 39, wherein the biasing member is in a relaxed state when the first and second sections are in the first state and in a compressed state when the first and second sections are in the second state. (Item 41) Item 40. The apparatus of item 39, wherein the biasing member has a relaxed state and an energized state, and the support plate has a displacement path between a first position when the biasing member is in the relaxed state and a second position when the biasing member is in the energized state. (Item 42) Item 42. The apparatus of item 41, wherein the displacement path is a linear displacement path. (Item 43) Item 42. The apparatus of item 41, wherein the displacement path is parallel to the axis of the pivot. (Item 44) Item 40. The apparatus of item 39, wherein the biasing member is a gas spring. (Item 45) A steam distillation apparatus comprising: A puddle and an evaporator having a first side in fluid communication with the sump and a second side in fluid communication with the vapor chest; a concentrate reservoir attached to the steam chest via an inlet path having a first portion and a second portion, the second portion being defined at least in part by an obstruction that extends into the concentrate reservoir transversely to the first portion and divides the concentrate reservoir into an unshielded section and a shielded section; a float assembly disposed within the shield section, the float assembly being displaceable over a range of displacement including points at or above an expected range of steam chest liquid levels; a sensor configured to monitor the position of the float assembly and output a data signal indicative of the liquid level in the vapor chamber based on the position of the float assembly; a compressor having an inlet establishing fluid communication with the vapor chest and an outlet establishing fluid communication with a condenser; An apparatus comprising: (Item 46) Item 46. The apparatus of item 45, wherein the sensor is an encoder. (Item 47) Item 46. The apparatus of item 45, wherein the float assembly includes at least one magnet. (Item 48) Item 48. The apparatus of item 47, wherein the sensor is a Hall effect sensor. (Item 49) Item 46. The apparatus of item 45, wherein the obstruction extends into the concentrate reservoir at an angle generally perpendicular to the first portion of the inlet path. (Item 50) Item 46. The device of item 45, further comprising a vent path extending from the concentrate reservoir to the steam chest. (Item 51) Item 51. The apparatus of item 50, wherein the vent path extends parallel to and above the first portion of the inlet path. (Item 52) Item 51. The apparatus of item 50, wherein the vent path has a cross-sectional area smaller than that of the first portion of the inlet path. (Item 53) Item 46. The apparatus of item 45, wherein the float assembly is pivotally mounted. (Item 54) Item 46. The apparatus of item 45, wherein the float assembly is displaceable about a pivot axis to which it is mounted. (Item 55) A steam distillation apparatus comprising: a sump having a source fluid input; an evaporator having a first side in fluid communication with the source fluid input via the sump and a second side in fluid communication with a steam chamber, the evaporator configured to convert source fluid from the source fluid input into low pressure steam and condensate as the source fluid travels toward the steam chamber; a concentrate reservoir attached to and positioned laterally relative to the steam chest, the concentrate reservoir including a concentrate level sensor configured to monitor a level of concentrate in the concentrate reservoir and generate a data signal indicative of the level of concentrate; a compressor having a low pressure steam inlet establishing fluid communication with the steam chest and a high pressure steam outlet establishing fluid communication with a condenser via a condenser inlet; a condenser in heat transfer relationship with a plurality of exterior surfaces of the evaporator, the condenser being configured to condense the high pressure vapor stream from the compressor by contacting the high pressure vapor stream with the plurality of exterior surfaces of the evaporator, the condenser including a condensing portion and a condensate accumulation portion; an auxiliary condensate reservoir in fluid communication with the condensate accumulation portion and attached to the condenser adjacent an accumulation surface of the accumulation portion, the auxiliary condensate reservoir including a condensate level sensor configured to monitor the level of condensate in the accumulation portion and generate a data signal indicative of the percentage that the accumulation portion is filled with condensate; An apparatus comprising: (Item 56) 56. The device of claim 55, wherein the accumulation portion has a volume of less than 10 liters. (Item 57) Item 56. The apparatus of item 55, wherein the plurality of exterior surfaces are exterior surfaces of a plurality of evaporator tubes contained within the evaporator. (Item 58) Item 56. The apparatus of item 55, wherein the plurality of exterior surfaces are the exterior surfaces of 90 to 100 evaporator tubes contained within the evaporator. (Item 59) Item 56. The apparatus of item 55, wherein the plurality of exterior surfaces are the exterior surfaces of 70 to 80 evaporator tubes contained within the evaporator. (Item 60) Item 56. The apparatus of item 55, wherein the condensate level sensor includes a float assembly mounted on a pivot, the float assembly being displaceable about the pivot through a displacement range that includes a point at the same height as the range of levels defined by the accumulation portion. (Item 61) Item 56. The apparatus of item 55, wherein the concentrate level sensor includes a float assembly disposed within a shielded section of the concentrate reservoir separated from an unshielded portion of the concentrate reservoir by a barrier. (Item 62) Item 62. The apparatus of item 61, wherein the float assembly is mounted on a pivot and is displaceable about the pivot through a range of displacement that includes points at or above the expected range of steam chest liquid levels. (Item 63) Item 62. The apparatus of item 61, wherein the concentrate level sensor is disposed within a sleeve that forms the barrier. (Item 64) 1. A concentrate level control system for a fluid vapor distillation apparatus, comprising: a source fluid input in selective fluid communication with the source fluid reservoir via at least one input valve; an evaporator in fluid communication with the source input and in fluid communication with a vapor chest, the evaporator configured to convert source fluid from the source fluid input into a vapor stream and a condensate stream as the source fluid travels toward the vapor chest; a concentrate reservoir attached to the steam chamber via an inlet passage and including an outlet disposed laterally therewith and selectively communicating with a concentrate destination via an outlet valve; a concentrate level sensor configured to generate a data signal indicative of a concentrate level within the steam chamber; a controller configured to control operation of the at least one inlet valve via a fluid input control loop and to analyze the data signal and deliberately modify the concentrate level in a predefined pattern by operating the outlet valve to a closed state when the data signal indicative of the concentrate level is below a first threshold and operating the outlet valve to an open state when the concentrate level is above a second threshold; and A system comprising: (Item 65) Item 65. The system of item 64, wherein the predefined pattern produces a sawtooth waveform when concentrate level is plotted over time. (Item 66) Item 66. The system of item 65, wherein the period of the sawtooth waveform depends, at least in part, on the fluid input command from the fluid input control loop. (Item 67) Item 67. The system of item 66, wherein the fluid input command is determined based on a predefined target concentrate production rate. (Item 68) Item 68. The system of item 67, wherein the controller is configured to operate in a plurality of operating states, and the predefined target concentrate production rate is state-specific. (Item 69) Item 65. The system of item 64, wherein the controller analyzes the data signal on a predefined basis. (Item 70) Item 65. The system of item 64, wherein the concentrate levels are assigned a predefined expected range, and the first threshold is less than or equal to 50% of the maximum level of the expected range. (Item 71) Item 71. The system of item 70, wherein the first threshold is 40% to 50% of the maximum level of the expected range. (Item 72) Item 65. The system of item 64, wherein the concentrate levels are assigned a predefined expected range, and the second threshold is greater than or equal to 50% of the maximum level of the expected range. (Item 73) Item 73. The system of item 72, wherein the second threshold is 50% to 60% of the maximum level of the expected range. (Item 74) Item 65. The system of item 64, wherein the concentrate levels are assigned a predefined expected range, and the first threshold is less than or equal to 40% of the maximum level of the expected range. (Item 75) Item 75. The system of item 74, wherein the first threshold is 40% to 30% of the maximum level of the expected range. (Item 76) Item 65. The system of item 64, wherein the concentrate levels are assigned a predefined expected range, and the second threshold is greater than or equal to 45% of the maximum level of the expected range. (Item 77) Item 77. The system of item 76, wherein the second threshold is 45% to 55% of the maximum level of the expected range. (Item 78) Item 65. The system of item 64, wherein the concentrate levels are assigned a predefined expected range, the first and second thresholds are defined as percentages of a maximum level of the expected range, and the second threshold is 4 to 20 percentage points above the first threshold. (Item 79) Item 65. The system of item 64, wherein the concentrate destination is a mixing tank. (Item 80) 1. A method for controlling the level of concentrate in a distillation device and regulating fluid flow within said distillation device, comprising: inputting a source fluid into the distillation device through at least one inlet valve; vaporizing at least a portion of the source fluid as it travels toward a steam chest to generate steam and a condensate; collecting the concentrate in a concentrate reservoir attached to and positioned laterally relative to the steam chest via the inlet passage; providing a data signal indicative of a concentrate level in the vapor chamber from a concentrate level sensor disposed within the concentrate reservoir; using a controller to regulate operation of the at least one inlet valve via a fluid input control loop and analyze the data signal, and modify the concentrate level in a predefined pattern by operating an outlet valve of the concentrate reservoir to a closed state when the data signal indicative of the concentrate level is below a first threshold and to an open state when the concentrate level is above a second threshold; A method comprising: (Item 81) 81. The method of claim 80, wherein modifying the concentrate level comprises modifying the concentrate level to produce a sawtooth waveform when the concentrate level is plotted over time. (Item 82) Item 81. The method of item 80, wherein analyzing the data signal includes analyzing the data signal on a predefined basis. (Item 83) 81. The method of claim 80, further comprising assigning a predefined expected range to the concentrate level and setting the first threshold to be less than or equal to 50% of the maximum level of the expected range. (Item 84) Item 84. The method of item 83, wherein setting the first threshold value includes setting the threshold value to 40% to 50% of the maximum level of the expected range. (Item 85) 81. The method of claim 80, further comprising assigning a predefined expected range of the concentrate level and setting the second threshold to be greater than or equal to 50% of the maximum level of the expected range. (Item 86) Item 86. The method of item 85, wherein setting the second threshold comprises setting the second threshold to 50% to 60% of a maximum level of the expected range. (Item 87) 81. The method of claim 80, further comprising assigning a predefined expected range to the concentrate level and setting the first threshold to be less than or equal to 40% of the maximum level of the expected range. (Item 88) Item 88. The method of item 87, wherein setting the first threshold value includes setting the threshold value to 40% to 30% of the maximum level of the expected range. (Item 89) 81. The method of claim 80, further comprising assigning a predefined expected range of concentrate levels and setting the second threshold to be greater than or equal to 45% of a maximum level of the expected range. (Item 90) Item 90. The method of item 89, wherein setting the second threshold comprises setting the second threshold to 45% to 55% of a maximum level of the expected range. (Item 91) 81. The method of claim 80, further comprising assigning a predefined expected range to the concentrate levels and setting the first and second thresholds as percentages of a maximum level of the expected range, the second threshold being 4 to 20 percentage points above the first threshold. (Item 92) 1. A temperature control system for controlling the temperature of a product process stream of a distillation device to a required temperature, comprising: a source fluid input in selective fluid communication with a source fluid reservoir via a set of fluid input valves; an evaporator in fluid communication with the source input and in fluid communication with a compressor, the evaporator configured to convert a source fluid from the source fluid input into a vapor stream and a concentrate stream; a condenser in fluid communication with the compressor configured to convert pressurized vapor from the compressor into condensate; a condensate flow path and a concentrate flow path including respective first and second heat exchangers, each of the first and second heat exchangers including a heat exchange portion of the source fluid flow path from the source fluid reservoir, the heat exchange portion being downstream of the source fluid input valve; a condensate temperature sensor configured to generate a data signal indicative of a condensate temperature, the condensate temperature sensor being positioned in the condensate flow path downstream of the first heat exchanger; and a controller configured to operate the set of input source valves based on a first control loop that governs the total open time for all of the input source valves of the set of input source valves, and a second control loop that receives the data signal and the desired temperature, divides the total open time among all of the input source valves, and adjusts the condensate temperature to the desired temperature; A system comprising: (Item 93) Item 93. The system of item 92, wherein the heat exchanging portions of the source fluid flow paths within the first and second heat exchangers are disposed countercurrently to their respective condensate and concentrate flow paths. (Item 94) Item 93. The system of item 92, further comprising a destination device in fluid communication with the condensate flow path via a point-of-use valve. (Item 95) Item 95. The system of item 94, wherein the required temperature is generated by the destination device. (Item 96) Item 95. The system of item 94, wherein the destination device is a medical system. (Item 97) Item 97. The system of item 96, wherein the medical system is configured to mix at least one dialysis solution. (Item 98) Item 95. The system of item 94, wherein the destination device is a dialysis machine. (Item 99) Item 95. The system of item 94, wherein the destination device is a hemodialysis machine. (Item 100) Item 93. The system of item 92, wherein at least one of the first and second control loops is a PID control loop. (Item 101) Item 101. The system of item 100, wherein the gain of at least one of the terms in the PID control loop is zero. (Item 102) Item 93. The system of item 92, wherein a feedforward term is combined with the output of the second control loop. (Item 103) Item 103. The system of item 102, wherein the feedforward term is based on an estimated division of the total open state time. (Item 104) Item 93. The system of claim 92, further comprising a concentrate level sensor configured to output a concentrate level data signal indicative of the concentrate level in the distillation device, and wherein the first control loop is configured to receive a target concentrate level and the current concentrate level data signal as inputs to the first control loop. (Item 105) Item 93. The system of item 92, wherein the controller is further configured to adjust the heater duty cycle based, at least in part, on the total open time for all input source valves of the set of input source valves. (Item 106) Item 106. The system of item 105, wherein the controller is configured to increase the heater duty cycle when the open time for all of the input source valves of the set of input source valves is increased. (Item 107) 1. A method for controlling the temperature of a product process stream of a distillation device to a required temperature, comprising: using a controller to regulate the flow of a source fluid input to the distillation device by operating a set of fluid input valves; converting at least a portion of the source fluid input into a vapor and a condensate in an evaporator; condensing the vapor into a condensate in a condenser; removing at least a portion of the condensate and the concentrate from the distillation device through separate condensate and concentrate flow paths; exchanging heat between the source fluid flow and the condensate flow path in a first heat exchanger and exchanging heat between the source fluid flow and the concentrate flow path in a second heat exchanger; providing a condensate temperature data signal to the controller from a temperature sensor in the condensate flow path located downstream of the first heat exchanger; and using a controller to determine a total open time for a set of fluid input valves based on a first control loop and divide the total open time between the set of fluid input valves based on a second control loop that receives the temperature data signal and a desired temperature. (Item 108) 108. The method of claim 107, further comprising flowing the concentrate and concentrate through the concentrate and concentrate flow paths in a countercurrent direction to the flow of the source fluid. (Item 109) Item 108. The method of item 107, further comprising providing the condensate to a destination device by activating a point-of-use valve downstream of the temperature sensor. (Item 110) Item 110. The method of item 109, wherein the required temperature is generated by the destination device. (Item 111) Item 110. The method of item 109, wherein the destination device is a medical system. (Item 112) 108. The method of claim 107, further comprising using the concentrate to mix the dialysate. (Item 113) Item 110. The method of claim 109, wherein the destination device is a dialysis machine. (Item 114) Item 110. The method of claim 109, wherein the destination device is a hemodialysis machine. (Item 115) Item 108. The method of item 107, wherein at least one of the first and second control loops is a PID control loop. (Item 116) Item 116. The method of item 115, further comprising setting at least one of the gains of the PID control loop to zero. (Item 117) Item 108. The method of item 107, further comprising combining a feedforward term with the output of the second control loop. (Item 118) Item 118. The method of item 117, further comprising determining the feedforward term based on an estimated division of a total open state time. (Item 119) Item 108. The method of claim 107, further comprising inputting a current concentrate level and a target concentrate level provided by a concentrate level sensor into the first control loop. (Item 120) Item 108. The method of item 107, further comprising adjusting the heater duty cycle based at least in part on the total open time for all input source valves of the set of input source valves. (Item 121) Item 121. The method of item 120, wherein adjusting the heater duty cycle includes increasing the heater duty cycle when the open time for all of the input source valves of the set of input source valves is increased. (Item 122) 1. A temperature control system for controlling the temperature of a product process stream of a distillation device to a required temperature, comprising: a first source fluid input and a second source fluid input in selective fluid communication with the first and second source fluid reservoirs via a first set of fluid input valves and a second set of fluid input valves, respectively; an evaporator in fluid communication with the first and second source fluid inputs and in fluid communication with a compressor, the evaporator having a heating element for converting source fluid from the first and second source fluid inputs into a vapor stream and a condensate stream as the source fluid travels toward the compressor; a condenser in fluid communication with the compressor configured to convert pressurized vapor from the compressor into condensate; a condensate flow path and a concentrate flow path including respective first and second heat exchangers, each of the first and second heat exchangers including a heat exchange portion of the source fluid flow path from the source fluid reservoir, the heat exchange portion being downstream of at least the first set of source fluid input valves; a condensate temperature sensor configured to generate a data signal indicative of a condensate temperature, the condensate temperature sensor being positioned in the condensate flow path downstream of the first heat exchanger; and a controller configured to operate the first set of input source valves based on a first control loop that governs a total open time for all input source valves of the first set of input source valves; and a second control loop that receives the data signal and the desired temperature, divides the total open time among all of the input source valves of the first set of input source valves, and adjusts the condensate temperature to the desired temperature; and a controller configured to monitor at least one process variable and operate the second set of input source valves when one of the at least one process variable is outside a predefined threshold; A system comprising: (Item 123) Item 123. The system of item 122, wherein the first set of fluid input valves includes at least one valve that is not included in the second set of fluid input valves. (Item 124) Item 123. The system of item 122, wherein one of the first and second source fluid inputs is temperature controlled. (Item 125) Item 123. The system of item 122, wherein the second source fluid input is temperature controlled. (Item 126) Item 126. The system of item 125, wherein the second source fluid input is a hot fluid input. (Item 127) Item 123. The system of item 122, wherein at least one process variable monitored by the controller is a heating element duty cycle. (Item 128) Item 123. The system of item 122, wherein at least one process variable monitored by the controller is an output of the first control loop. (Item 129) Item 123. The system of item 122, wherein the at least one process variable is compressor speed. (Item 130) Item 123. The system of item 122, wherein the heat exchange portion of the source fluid flow path is a common flow path for fluids from the first and second source fluid inputs. (Item 131) Item 123. The system of item 122, wherein the heat exchange portion of the source fluid flow path is a flow path for fluid from the first source fluid input that is not shared by fluid from the second source fluid input. (Item 132) 1. A temperature control system for controlling the temperature of a product process stream of a distillation device to a required temperature, comprising: a source fluid input in selective fluid communication with a source fluid reservoir via a set of fluid input valves; an evaporator in selective fluid communication with the source fluid input via a bypass valve and in fluid communication with a compressor, the evaporator configured to convert source fluid from the source fluid input into a vapor stream and a concentrate stream as the source fluid travels toward the compressor; a condenser in fluid communication with the compressor configured to convert pressurized vapor from the compressor into condensate; a condensate flow path and a concentrate flow path including respective first and second heat exchangers, each of the first and second heat exchangers including a heat exchange portion of the source fluid flow path from the source fluid reservoir, the heat exchange portion being downstream of the source fluid input valve; a condensate temperature sensor configured to generate a data signal indicative of a condensate temperature, the condensate temperature sensor being positioned in the condensate flow path downstream of the first heat exchanger; and a controller configured to operate the set of input source valves based on a first control loop that governs the total open time for all of the input source valves of the set of input source valves, and a second control loop that receives the data signal and the desired temperature, divides the total open time among all of the input source valves, and adjusts the condensate temperature to the desired temperature; Equipped with the bypass valve is disposed in the source fluid flow path downstream of a heat exchange portion of the source fluid flow path, the bypass valve having a diversion valve state that directs fluid from the source reservoir to a drain destination, and the controller is configured to actuate the bypass valve to the diversion valve state when the controller determines that at least one process variable is outside a predetermined threshold. (Item 133) Item 133. The system of item 132, wherein the at least one process variable is a relationship between the condensate temperature and a source fluid temperature provided by a source fluid temperature sensor. (Item 134) Item 133. The system of item 132, wherein the at least one process variable is source fluid temperature sensed by a source fluid temperature sensor. (Item 135) Item 133. The system of item 132, wherein the at least one process variable is defined at least in part by the condensate temperature and a source fluid temperature sensed by a source fluid temperature sensor. (Item 136) Item 133. The system of item 132, wherein the controller is configured to modify the duty cycle of at least one of the input source valves when the bypass valve is in the diversion valve state. (Item 137) Item 133. The system of item 132, wherein the controller is configured to increase the duty cycle of at least one of the input source valves when the bypass valve is in the diverter valve state. (Item 138) Item 133. The system of item 132, wherein the controller is configured to modify the duty cycle of at least one of the input source valves to 90-100% when the bypass valve is in the diversion valve state. (Item 139) 139. The system of any one of items 136-138, wherein one of at least one of the input source valves is a valve that controls the flow of source fluid through the heat exchange portion of the first heat exchanger. (Item 140) 1. A temperature control system for controlling the temperature of a product process stream of a distillation system to a required temperature, comprising: a source fluid input in selective fluid communication with the source fluid reservoir via a set of fluid input valves; a distillation device configured to generate a concentrate stream and a condensate stream; a condensate flow path and a concentrate flow path including respective first and second heat exchangers, each of the first and second heat exchangers including a heat exchange portion of the source fluid flow path from the source fluid reservoir, the heat exchange portion being downstream of the source fluid input valve; a condensate temperature sensor configured to generate a data signal indicative of a condensate temperature, the condensate temperature sensor being positioned in the condensate flow path downstream of the first heat exchanger; and a point-of-use device in selective communication with the condensate flow path, the point-of-use device having an outlet flow path for an output fluid generated by the point-of-use device, the output flow path having a third heat exchanger that includes a heat exchange portion of a branch of the source fluid flow path; a controller configured to actuate a set of input source valves based on first and second control loops governing flow of source fluid through heat exchange portions of the first and second heat exchangers and based on at least one process variable, the controller actuating a branch valve in a branch of the source fluid flow path when the at least one process variable is outside a predetermined threshold; and A system comprising: (Item 141) Item 141. The system of item 140, wherein the at least one process variable is a relationship between the condensate temperature and a source fluid temperature provided by a source fluid temperature sensor. (Item 142) Item 141. The system of item 140, wherein the at least one process variable is source fluid temperature sensed by a source fluid temperature sensor. (Item 143) Item 141. The system of item 140, wherein the at least one process variable is defined at least in part by the condensate temperature and a source fluid temperature sensed by a source fluid temperature sensor. (Item 144) Item 141. The system of item 140, wherein the point-of-use device is a medical device. (Item 145) Item 141. The system of item 140, wherein the point-of-use device is a dialysis machine. (Item 146) Item 141. The system of item 140, wherein the point-of-use device is a hemodialysis machine or a peritoneal dialysis machine. (Item 147) Item 141. The system of item 140, wherein the branch of the source fluid flow path is positioned upstream of the heat exchange portion of the source fluid flow path within the first and second heat exchangers. (Item 148) Item 141. The system of item 140, wherein the output fluid is dialysate waste. (Item 149) 1. A condensate buildup rate control system for controlling the rate of condensate buildup in a distillation device, comprising: a source fluid input in selective fluid communication with a source fluid reservoir via a set of fluid input valves; an evaporator in fluid communication with the source input and in fluid communication with a compressor having an impeller operably coupled to an impeller motor, the evaporator configured to convert source fluid from the source fluid input into a vapor stream and a concentrate stream as the source fluid travels toward the compressor; a condenser in heat transfer relationship with a plurality of exterior surfaces of the evaporator, the condenser configured to condense the high pressure vapor stream from the compressor by contacting the high pressure vapor stream with the plurality of exterior surfaces of the evaporator; a condensate level sensor configured to sense a current level of condensate in the condenser; and at least one controller configured to regulate the rotational speed of the impeller by periodically generating an impeller motor command based on a last motor speed command, a motor speed target, and a speed command increment limit, the motor speed target being calculated by a control loop that receives the current condensate level and a desired condensate level as control loop inputs; A system comprising: (Item 150) Item 149. The system of item 149, wherein the speed command increment limit is ≦10 rpm / sec. (Item 151) Item 149. The system of item 149, wherein the speed command increment limit is ≦5 rpm / sec. (Item 152) Item 149. The system of item 149, wherein the controller is configured to compare the impeller motor command with a minimum command speed threshold and a maximum command speed threshold, and adjust the impeller motor command to a modified impeller motor command equal to the minimum command speed threshold when the impeller motor command is below the minimum command speed threshold, and equal to the maximum command speed threshold when the impeller motor command is above the maximum command speed threshold. (Item 153) Item 153. The system of item 152, wherein the minimum command speed threshold is 1,500 to 2,500 rpm. (Item 154) Item 153. The system of item 152, wherein the minimum command speed threshold is 2,000 rpm. (Item 155) Item 153. The system of item 152, wherein the maximum command velocity threshold is calculated each time the motor velocity command is generated. (Item 156) Item 156. The system of item 155, wherein the maximum commanded velocity threshold is calculated based on at least one motor parameter. (Item 157) Item 156. The system of item 155, further comprising: a motor temperature sensor configured to output a temperature data signal indicative of a temperature of the impeller motor; and a power factor correction current monitoring circuit configured to output a PFC data signal indicative of a current power factor correction current, wherein the maximum command speed threshold is calculated based on the temperature data signal and the PFC data signal. (Item 158) Item 156. The system of item 155, wherein the maximum commanded speed is capped at a predetermined value. (Item 159) Item 159. The system according to item 158, wherein the predetermined value is 4,500 to 6,500 rpm. (Item 160) Item 159. The system of item 158, wherein the predetermined value is 5,000 rpm. (Item 161) Item 159. The system of item 158, wherein the predetermined value is 2.5 times greater than the minimum commanded speed threshold. (Item 162) 1. A method for controlling the rate of condensate accumulation in a distillation device, comprising: providing a source fluid input to said distillation device; evaporating at least a portion of the source fluid input into a low pressure vapor in an evaporator; compressing the low pressure steam into high pressure steam via an impeller; condensing the high pressure steam into a condensate in a condenser and transferring heat from the high pressure steam to the evaporator; providing a controller with a level of condensate in the condenser sensed by a condensate level sensor; calculating, with the controller, a motor speed target based on the condensate level and a desired condensate level; using a controller to regulate the rotational speed of the impeller by periodically generating impeller motor commands based on the last motor speed command, a motor speed target, and a speed command increment limit; A method comprising: (Item 163) Item 163. The method of item 162, wherein the speed command increment limit is ≦10 rpm / sec. (Item 164) Item 163. The method of item 162, wherein the speed command increment limit is ≦5 rpm / sec. (Item 165) Item 163. The method of claim 162, further comprising using a controller to compare the impeller motor command to a minimum command speed threshold and a maximum command speed threshold, and adjusting the impeller motor command to a modified impeller motor command equal to the minimum command speed threshold when the impeller motor command is below the minimum command speed threshold, and equal to the maximum command speed threshold when the impeller motor command is above the maximum command speed threshold. (Item 166) Item 166. The method of item 165, wherein the minimum command speed threshold is 1,500 to 2,500 rpm. (Item 167) Item 166. The method of item 165, wherein the minimum command speed threshold is 2,000 rpm. (Item 168) Item 166. The method of claim 165, further comprising calculating the maximum command velocity threshold each time the motor velocity command is generated. (Item 169) Item 169. The method of item 168, wherein calculating the maximum command velocity threshold includes calculating the maximum command velocity threshold based on at least one motor parameter. (Item 170) Item 169. The method of claim 168, further comprising providing a temperature data signal indicative of the temperature of the motor from a motor temperature sensor to the controller, and providing a power factor correction data signal indicative of a current power factor correction current from a monitoring circuit to the controller. (Item 171) 171. The method of claim 170, further comprising calculating the maximum commanded speed threshold based on the temperature data signal and the power factor correction data signal. (Item 172) Item 169. The method of item 168, further comprising capping the maximum commanded velocity threshold at a predetermined value. (Item 173) Item 173. The method according to Item 172, wherein the predetermined value is 4,500 to 6,500 rpm. (Item 174) Item 173. The method of item 172, wherein the predetermined value is 5,000 rpm. (Item 175) Item 173. The method of item 172, wherein the predetermined value is 2.5 times greater than the minimum commanded speed threshold. (Item 176) 1. A distillation device comprising: a source fluid input in selective fluid communication with a source fluid reservoir via a set of fluid input valves; an evaporator in fluid communication with the source input and in fluid communication with a compressor, the evaporator configured to convert source fluid from the source fluid input into a vapor stream and a concentrate stream as the source fluid travels toward the compressor; a condenser in fluid communication with the compressor configured to convert pressurized vapor from the compressor into condensate; a condensate flow path and a concentrate flow path including respective first and second heat exchangers, each of the first and second heat exchangers including a heat exchange portion of the source fluid flow path from the source fluid reservoir, the heat exchange portion being downstream of the source fluid input valve; a condensate temperature sensor configured to generate a data signal indicative of a condensate temperature, the condensate temperature sensor being positioned in the condensate flow path downstream of the first heat exchanger; and a controller configured to operate the set of input source valves based on a first multi-modal control loop that generates a number of interim total open commands for all of the input source valves of the set of input source valves, a slider that generates a single total open command from the number of interim commands, and a second control loop that receives the data signal and a temperature setpoint, distributes the total open command among all of the input source valves, and adjusts the condensate temperature to the temperature setpoint; A device comprising: (Item 177) Item 177. The device of item 176, wherein the heat exchanging portions of the source fluid flow paths in the first and second heat exchangers are arranged countercurrently to their respective condensate and concentrate flow paths. (Item 178) Item 177. The device of item 176, wherein the controller is configured to operate in a plurality of operating states, and the temperature set point is dependent on the state. (Item 179) Item 177. The device of item 176, further comprising a destination device in fluid communication with the condensate flow path via a point-of-use valve. (Item 180) Item 179, wherein the destination device is a medical system. (Item 181) Item 181. The device of item 180, wherein the medical system is configured to mix at least one dialysis solution. (Item 182) Item 179, wherein the destination device is a dialysis machine. (Item 183) Item 179, wherein the destination device is a hemodialysis machine. (Item 184) Item 177. The device of item 176, wherein at least one of the first multimodal control loop and the second control loop comprises a PID control loop. (Item 185) Item 185. The device of item 184, wherein the gain of at least one of the terms in the PID control loop is zero. (Item 186) Item 177. The device of item 176, wherein the number of interim total open state commands is regulated by the output of at least one regulator control loop. (Item 187) Item 187. The device of item 186, wherein the distillation device further comprises a sump intermediate the source input and the evaporator, and one of the at least one regulator control loop is configured to produce an output based on a target sump temperature and a current sump temperature measured by a sump temperature sensor configured to generate a data signal representative of the temperature of the fluid in the sump. (Item 188) Item 187. The device of item 186, wherein one of the at least one regulator control loop is configured to produce an output based on a target steam temperature and a current steam temperature measured by a steam temperature sensor configured to generate a data signal representative of the temperature of the steam flow. (Item 189) Item 177. The device of claim 176, further comprising a concentrate level sensor configured to output a concentrate level data signal indicative of the concentrate level in the distillation device, the controller configured to determine a current blowdown rate from the concentrate level data signal, and the first multi-modal control loop configured to receive a target blowdown rate and the current blowdown rate data signal as inputs. (Item 190) Item 177. The device of item 176, wherein the device further includes an evaporator level sensor configured to output an evaporator data signal, and the controller is configured to generate at least one of the interim total open state commands based, at least in part, on input of a target evaporator sensor level and the evaporator data signal. (Item 191) Item 191. The device of item 190, wherein the target evaporator sensor level and the evaporator data signal are input to a derivative controller. (Item 192) Item 192. The device of item 191, wherein the derivative controller is a PID controller having a D term gain that is at least one order of magnitude greater than the P and I terms. (Item 193) Item 177. The device of item 176, wherein at least one of the interim total open state commands is a first production temperature state command and at least one of the interim total open state commands is a second production temperature state command. (Item 194) A steam distillation apparatus comprising: a sump having a source fluid input; an evaporator having a first side in fluid communication with the source fluid input via the sump and a second side in fluid communication with a vapor chamber, the evaporator configured to convert source fluid from the source fluid input into low pressure vapor and condensate, wherein a non-uniform liquid level exists within the evaporator during operation; an evaporator reservoir disposed laterally relative to the evaporator and in fluid communication therewith via the water sump, the evaporator reservoir including a level sensor configured to monitor a level of a water column in the evaporator reservoir and generate a data signal indicative of the level of the water column; a compressor having a low pressure steam inlet establishing fluid communication with the steam chest and a high pressure steam outlet establishing fluid communication with a condenser via a condenser inlet; a condenser in heat transfer relationship with a plurality of exterior surfaces of the evaporator, the condenser being configured to condense the high pressure vapor stream from the compressor by contacting the high pressure vapor stream with the plurality of exterior surfaces of the evaporator, the condenser including a condensing portion and a condensate accumulation portion; a processor configured to actuate a set of input source valves to the source fluid input based in part on the data signal; An apparatus comprising: (Item 195) Item 195. The apparatus of item 194, wherein the level sensor includes a displaceable member that is displaceable over a displacement range that is less than the height of the evaporator reservoir. (Item 196) Item 195. The apparatus of item 194, wherein the level sensor includes a displaceable member displaceable over a displacement range extending from a first end portion of the evaporator reservoir to at least a midpoint of the evaporator reservoir, the displacement range being a distance less than 70% of the height of the evaporator reservoir. (Item 197) Item 197. The apparatus of item 196, wherein the first end is the end of the evaporator reservoir most distal to the sump. (Item 198) Item 195. The apparatus of item 194, wherein the evaporator reservoir communicates with the vapor chest via a vent path extending from a first end portion of the evaporator reservoir. (Item 199) Item 199. The apparatus of item 198, wherein the ventilation path extends from the evaporator reservoir to a concentrate reservoir attached to and positioned laterally relative to the vapor chest. (Item 200) Item 195. The apparatus of item 194, wherein the height of the evaporator reservoir exceeds the height of the evaporator. (Item 201) Item 195. The apparatus of item 194, wherein the processor is configured to determine a total open time for a set of input source valves based in part on a target water column level and a current water column level determined through analysis of the data signal. (Item 202) Item 202. The apparatus of item 201, wherein the processor is configured to determine a total open time for a set of input source valves based, in part, on the output of a PID controller that receives the target water column level and the current water column level as inputs. (Item 203) Item 203. The apparatus of item 202, wherein a gain for at least one of the P term, I term, and D term of the PID controller is zero. (Item 204) Item 203. The apparatus of item 202, wherein a gain for the D term of the PID controller exceeds a gain for the P and I terms of the PID controller by at least an order of magnitude. (Item 205) Item 203. The apparatus of item 202, wherein the gain for the D term of the PID controller exceeds the gain for the P and I terms of the PID controller by more than two orders of magnitude. (Item 206) Item 202. The apparatus of item 201, wherein the processor is configured to determine the total open state time based in part on a target blowdown rate and a current blowdown rate as indicated from a blowdown level data signal produced by a blowdown level sensor in a blowdown reservoir attached to the steam chest. (Item 207) Item 195. The apparatus of item 194, wherein the processor is configured to determine a total open state command based in part on the output of at least one regulator control loop. (Item 208) Item 208. The apparatus of item 207, wherein one of the at least one regulator control loops is configured to produce an output based on a target sump temperature and a current sump temperature measured by a sump temperature sensor configured to generate a data signal representative of the temperature of fluid in the sump. (Item 209) Item 208. The apparatus of item 207, wherein one of the at least one regulator control loop is configured to produce an output based on a target steam temperature and a current steam temperature measured by a steam temperature sensor configured to generate a data signal representative of the temperature of the steam flow. (Item 210) Item 195. The apparatus of item 194, wherein the controller is configured to modify a total open state command for a set of input source valves in response to a change in the water column level indicated by the data signal. (Item 211) Item 195. The apparatus of item 194, wherein the controller is configured to modify a total open state command for a set of input source valves in proportion to the rate of change of the water column as indicated by the data signal. (Item 212) 1. A method for controlling the flow of a source fluid into a distillation device, comprising: establishing a non-uniform liquid level in an evaporator of the distillation device; sensing a liquid column level in an evaporator reservoir with a first level sensor in fluid communication with and positioned at the same height as the evaporator; sensing a concentrate level in a concentrate reservoir in fluid communication with the evaporator with a second level sensor; generating, with a processor, a source inlet valve open time command based at least in part on the concentrate level and a target concentrate accumulation rate and a delta between the liquid column level and a target liquid column level; commanding a number of source inlet valves to open based on said source inlet valve open time commands; A method comprising: (Item 213) Item 213. The method of item 212, wherein sensing the liquid column level includes displacing a displaceable member over a displacement range that is less than the height of the evaporator reservoir. (Item 214) Item 213. The method of item 212, wherein sensing the liquid column level includes displacing a displaceable member over a displacement range extending from a first end portion of the evaporator reservoir to at least a midpoint of the evaporator reservoir, the displacement range being a distance less than 70% of the height of the evaporator reservoir. (Item 215) Item 215. The method of claim 214, wherein the first end is the end of the evaporator reservoir most distal to a sump of the distillation device. (Item 216) Item 213. The method of claim 212, further comprising venting air from the evaporator reservoir through a vent path into a vapor chest of the distillation device located above the evaporator. (Item 217) Item 217. The method of item 216, wherein the ventilation path extends from the evaporator reservoir to a concentrate reservoir attached to and positioned laterally relative to the vapor chest. (Item 218) Item 213. The method of item 212, wherein generating the source inlet valve open time command includes inputting the delta into a PID controller. (Item 219) Item 219. The apparatus of item 218, wherein a gain for at least one of the P term, I term, and D term of the PID controller is zero. (Item 220) Item 219. The apparatus of item 218, wherein the gain for the D term of the PID controller exceeds the gains for the P and I terms of the PID controller by at least an order of magnitude. (Item 221) Item 219. The apparatus of item 218, wherein the gain for the D term of the PID controller exceeds the gain for the P and I terms of the PID controller by more than two orders of magnitude. (Item 222) Item 213. The apparatus of item 212, wherein generating the source inlet valve open time command includes determining a current concentrate accumulation rate from the concentrate level and calculating a delta between a target concentrate rate and the current concentrate accumulation rate. (Item 223) Item 213. The apparatus of item 212, wherein generating the source inlet valve open time command includes generating an output of at least one regulator control loop. (Item 224) Item 224. The apparatus of item 223, wherein the method further includes sensing a current sump temperature using a sump temperature sensor, and generating an output for at least one regulator control loop includes producing the output based on a target sump temperature and the current sump temperature. (Item 225) Item 224. The apparatus of item 223, wherein the method further includes sensing the temperature of the vapor flow in the distillation device using a vapor temperature sensor, and generating at least one regulator controller output includes producing the output based on a target vapor temperature and a current vapor temperature. (Item 226) Item 213. The apparatus of item 212, wherein the method further includes modifying the source inlet valve open time command in response to a change in the liquid column level. (Item 227) Item 213. The apparatus of item 212, wherein the method further comprises modifying the source inlet valve open time command in proportion to a rate of change of the liquid column level. (Item 228) 1. A fluid vapor distillation apparatus comprising: At least one controller; a source inlet in selective fluid communication with the fluid source via at least one valve; an evaporator in fluid communication with the source inlet; a steam chest coupled to the evaporator and in fluid communication with a compressor, an exterior surface of the steam chest forming a portion of an inlet flow path to the compressor and a portion of an outlet flow path to an outlet of the compressor; a concentrate reservoir attached to the steam chamber via an inlet passage and positioned laterally relative to the steam chamber such that at least a portion of the concentrate reservoir is at the same height as the steam chamber; a condenser in fluid communication with the compressor outlet via a linear flow path, the linear flow path including a condenser inlet fixedly attached to a sheet having a first surface defining a portion of the vapor chest and an opposing surface defining a portion of the condenser; a product process stream reservoir coupled to the condenser by a product reservoir inlet and positioned laterally relative to the condenser such that at least a portion of the product process stream reservoir is flush with the condenser; An apparatus comprising: (Item 229) Item 229. The apparatus of item 228, wherein the inflow path includes an obstacle. (Item 230) Item 230. The apparatus of item 229, wherein the obstacle comprises a wall extending into the concentrate reservoir at an angle generally perpendicular to the inlet path. (Item 231) Item 229. The apparatus of item 229, wherein the obstruction extends into the concentrate reservoir and divides the concentrate reservoir into a first portion and a second shielded portion. (Item 232) Item 229. The apparatus of item 228, wherein the obstruction includes at least one vent port. (Item 233) Item 229. The apparatus of item 228, wherein the product reservoir inlet is adjacent to a product accumulation surface of the condenser. (Item 234) Item 229. The apparatus of item 228, wherein the compressor is driven by a motor that is partially disposed within a receiving well that fits into the side of the steam chest. (Item 235) Item 229. The apparatus of item 228, wherein the compressor includes an impeller that extends laterally relative to the steam chest and rotates about an axis that is parallel to the longitudinal axis of the steam chest. (Item 236) 1. A distillation device comprising: a source fluid input in selective fluid communication with the source via a set of fluid input valves; an evaporator in fluid communication with the source input and in fluid communication with a compressor having an impeller operably coupled to an impeller motor, the evaporator configured to convert source fluid from the source fluid input into a vapor stream and a concentrate stream as the source fluid travels toward the compressor; a condenser in heat transfer relationship with a plurality of exterior surfaces of the evaporator, the condenser configured to condense the high pressure vapor stream from the compressor by contacting the high pressure vapor stream with the plurality of exterior surfaces of the evaporator; a concentrate level sensor disposed above the evaporator, the concentrate level sensor having an inlet path and a longitudinal axis extending alongside the evaporator, the concentrate level sensor configured to sense a current level of concentrate in a concentrate reservoir; at least one controller configured to regulate the rotational speed of the impeller in the cold distillate production state and the hot distillate production state by periodically generating an impeller motor command based on a cold distillate production nominal speed command in the cold distillate production state and a hot distillate production nominal speed command in the hot distillate production state, wherein the cold distillate production nominal speed command is a motor speed command that is higher than the hot distillate production nominal speed command; A distillation device comprising: (Item 237) Item 237. The distillation device of item 236, wherein adjustments are made to the impeller motor command based on a data signal from the concentrate level sensor indicative of the level of concentrate in the concentrate reservoir. (Item 238) Item 238. The distillation device of item 237, wherein the adjustment is limited by an impeller motor command increment limit. (Item 239) Item 239. The distillation device of item 238, wherein the impeller motor command increment limit is ≦10 rpm / sec. (Item 240) Item 239. The distillation device of item 238, wherein the impeller motor command increment limit is ≦5 rpm / sec. (Item 241) Item 238. The distillation device of item 237, wherein the impeller motor command is decremented when the data signal indicates that the level of concentrate in the concentrate reservoir is above a first threshold. (Item 242) Item 242. The distillation device of item 241, wherein the first threshold is defined as the concentrate level when the concentrate reservoir is at a predefined fill value of 65-80%. (Item 243) Item 238. The distillation device of item 237, wherein the impeller motor command is maintained at or below a previously commanded impeller motor command value when the data signal indicates that the level of concentrate in the concentrate reservoir is above a first threshold. (Item 244) Item 244. The distillation device of item 243, wherein the first threshold is defined as the concentrate level when the concentrate reservoir is at a predefined fill value of 65-80%. (Item 245) Item 238. The distillation device of item 237, wherein the impeller motor command is incremented when the data signal indicates that the level of concentrate in the concentrate reservoir is above a second threshold. (Item 246) Item 237. The distillation device of item 236, wherein the hot distillate production nominal rate command is a calibration value defined during manufacture. (Item 247) Item 237. The distillation device of item 236, wherein the hot distillate production nominal rate command is less than 80% of the cold distillate production nominal rate command. (Item 248) Item 237. The distillation device of item 236, wherein the hot distillate production nominal rate command is greater than 45% of the cold distillate production nominal rate command. (Item 249) Item 237. The distillation device of item 236, wherein the cold distillate production nominal speed command is 4,500 rpm. (Item 250) Item 237. The distillation device of item 236, wherein the cold distillate production nominal speed command is 5,000 rpm. (Item 251) 1. A method for controlling a compressor of a distillation device, comprising: opening at least one fluid input valve to deliver a source fluid from a fluid source into a reservoir of said distillation device; converting the source fluid into a concentrate stream and a vapor stream in an evaporator; determining, with a processor, a state-specific compressor speed command, the compressor speed command being based on a cold distillate production nominal speed command in a cold distillate production state and a hot distillate production nominal speed command in a hot distillate production state, the cold distillate production nominal speed command being a motor speed command that is faster than the hot distillate production nominal speed command; generating, with the processor, a final command speed based on the compressor speed command; commanding rotation of the compressor impeller at the final command speed with the processor; compressing the vapor stream through the compressor; condensing the vapor stream into a condensate and transferring heat to the evaporator as the vapor stream condenses; A method comprising: (Item 252) Item 252. The method of claim 251, further comprising sensing the level of concentrate in a concentrate reservoir in fluid communication with the evaporator using a level sensor. (Item 253) Item 253. The method of item 252, wherein generating the final command speed includes determining an adjustment to the compressor speed command based on a level of concentrate. (Item 254) Item 254. The method of claim 253, wherein determining the adjustment includes decrementing the compressor speed command when the concentrate level is above a first threshold. (Item 255) Item 255. The method of item 254, wherein the first threshold is defined as the concentrate level when the concentrate reservoir is at a predefined fill value of 65-80%. (Item 256) Item 254. The method of claim 253, wherein determining the adjustment includes maintaining the final command rate at or below a previously commanded final command rate when the level of concentrate is above a first threshold. (Item 257) Item 254. The method of claim 253, wherein determining the adjustment includes decrementing the compressor speed command when the concentrate level is above a second threshold. (Item 258) Item 252. The method of item 251, wherein generating the final command speed includes determining an adjustment to the compressor speed command. (Item 259) Item 259. The method of item 258, wherein the adjustment is limited by an increment limit. (Item 260) Item 259. The method of item 258, wherein the increment limit is ≦10 rpm / sec. (Item 261) Item 259. The method of item 258, wherein the increment limit is ≦5 rpm / sec. (Item 262) Item 252. The method according to item 251, wherein the hot distillate production nominal rate command is a calibration value defined during production. (Item 263) Item 252. The method of claim 251, wherein the hot distillate production nominal rate command is less than 80% of the cold distillate production nominal rate command. (Item 264) Item 252. The method of claim 251, wherein the hot distillate production nominal rate command is greater than 45% of the cold distillate production nominal rate command. (Item 265) Item 252. The method of claim 251, wherein the cold distillate production nominal speed command is 4,500 rpm. (Item 266) Item 252. The method of claim 251, wherein the cold distillate production nominal speed command is 5,000 rpm. (Item 267) 1. A distillation device comprising: a reservoir in selective fluid communication with the source via a set of fluid input valves; at least one heating element and at least one basin temperature sensor within the basin, the basin temperature sensor configured to generate a basin temperature data signal; an evaporator having a first side in fluid communication with the sump and a second side in fluid communication with a compressor having an impeller operably coupled to an impeller motor, the evaporator configured to convert a source fluid from the source fluid input into a vapor stream and a condensate; a condenser in heat transfer relationship with a plurality of exterior surfaces of the evaporator, the condenser configured to condense the high pressure vapor stream from the compressor by contacting the high pressure vapor stream with the plurality of exterior surfaces of the evaporator; a concentrate level sensor disposed above the evaporator, the concentrate level sensor having an inlet path and a longitudinal axis extending alongside the evaporator, the concentrate level sensor configured to sense a current level of concentrate in a concentrate reservoir; a steam temperature sensor disposed in a flow path of the steam flow and configured to generate a steam temperature data signal; at least one controller configured to determine a duty cycle command for the at least one heating element, the duty cycle command based at least in part on a target temperature of the steam flow, the steam temperature data signal, the sump temperature data signal, and a total source open command for a set of fluid input valves; A distillation device comprising: (Item 268) 268. The distillation device of claim 267, wherein the target temperature of the vapor stream is 108°C. (Item 269) Item 268. The distillation device of item 267, wherein the controller is configured to adjust the duty cycle command to conform to at least one limit. (Item 270) 269. The distillation device of claim 269, wherein the limit is a maximum power consumption limit. (Item 271) Item 268. The distillation device of item 267, wherein the controller is configured to adjust the duty cycle command based, at least in part, on the power consumption of the compressor. (Item 272) Item 268. The distillation device of item 267, wherein the controller is configured to determine a power consumption of the compressor and calculate a limit on the duty cycle command by subtracting the power consumption of the compressor from a predefined power value. (Item 273) Item 273. The distillation device of item 272, wherein the predefined power value is defined as the maximum total power for the system. (Item 274) Item 268. The distillation device of item 267, wherein the duty cycle command is limited to a predefined maximum duty cycle. (Item 275) 275. The distillation device of claim 274, wherein the predefined maximum duty cycle is less than or equal to a 90% duty cycle. (Item 276) Item 268. The distillation device of item 267, wherein the target temperature of the vapor stream is state specific. (Item 277) Item 277. A distillation device according to item 276, wherein the target temperature in a low temperature distillate production state is higher than the target temperature in a high temperature distillate production state. (Item 278) Item 277. The distillation device of item 276, wherein the target temperature of the vapor stream in the first...

Claims

[Claim 1] The invention described in this specification.

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