Air handler heat transfer rate control for climate control systems

Abstract

A climate control system for conditioning an interior space is described. The climate control system includes a chiller, an air handler and ducting. The climate control system additionally includes one or more controllers that are configured to set a first target for a performance metric for the airflow based on a desired climate parameter for the interior space. The one or more controllers of the climate control system further to set a second target for a heat transfer rate for the coil of the air handler based on the first target. In addition, the one or more controllers of the climate control system to adjust a flow rate of heat transfer fluid through the coil to reduce an error associated with the second target.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] Not applicable.BACKGROUND

[0002] A climate control system may exchange heat between an interior space and an ambient environment via one or more fluid circuits. For instance, a climate control system may include a refrigerant circuit that is configured to transfer heat by selectively changing the phase of the refrigerant from a liquid to a vapor (and vice versa). In addition, some climate control systems, such as chillers, may include additional fluid circuits to exchange heat between the refrigerant circuit and other heat sink(s) / source(s), such the interior space(s), or the ambient environment.BRIEF SUMMARY

[0003] The present disclosure includes, without limitation, the following examples.

[0004] One embodiment is a method that controls climate control system. The method further sets a first target for a performance metric for an airflow through an air handler of a climate control system. The method additionally sets a second target for a heat transfer rate for a coil of the air handler based on the first target. In addition, the method adjusts a flow rate of heat transfer fluid through the coil to reduce an error associated with the second target.

[0005] One embodiment is a climate control system for conditioning an interior space. The climate control system includes a chiller that is configured to exchange heat with a flow of heat transfer fluid. In addition, the climate control system includes an air handler including a coil that is configured to receive the flow of heat transfer fluid therethrough. The climate control system further includes ducting coupled to the air handler that is configured to circulate an airflow between the interior space and the air handler. The climate control system additionally includes one or more controllers that are configured to set a first target for a performance metric for the airflow based on a desired climate parameter for the interior space. The one or more controllers of the climate control system further to set a second target for a heat transfer rate for the coil of the air handler based on the first target. In addition, the one or more controllers of the climate control system to adjust a flow rate of heat transfer fluid through the coil to reduce an error associated with the second target.

[0006] One embodiment is a non-transitory, machine-readable medium comprising instructions, which when executed by one or more processors. The machine-readable medium causes the one or more processors to set a first target for a performance metric for an airflow through an air handler of a climate control system. In addition, the machine-readable medium causes the one or more processors to set a second target for a heat transfer rate for a coil of the air handler based on the first target. The machine-readable medium causes the one or more processors further to adjust a flow rate of heat transfer fluid through the coil to reduce an error associated with the second target.

[0007] Embodiments described herein comprise a combination of features and characteristics intended to address various shortcomings associated with certain prior devices, systems, and methods. The foregoing has outlined rather broadly the features and technical characteristics of the disclosed embodiments in order that the detailed description that follows may be better understood. The various characteristics and features described above, as well as others, will be readily apparent to those having ordinary skill in the art upon reading the following detailed description, and by referring to the accompanying drawings. It should be appreciated that this disclosure may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes as the disclosed embodiments. It should also be realized that such equivalent constructions do not depart from the spirit and scope of the principles disclosed herein.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] For a detailed description of various embodiments, reference will now be made to the accompanying drawings in which:

[0009] FIG. 1 is a schematic diagram of a climate control system according to some embodiments disclosed herein;

[0010] FIG. 2 is a flow chart of control logic that may be employed by a controller of the climate control system of FIG. 1 according to some embodiments disclosed herein;

[0011] FIG. 3 is another schematic diagram of the climate control system of FIG. 1, in which the climate control system includes a plurality of chillers and a plurality of air handlers according to some embodiments disclosed herein;

[0012] FIG. 4 is a diagram of a method of controlling a climate control system according to some embodiments disclosed herein; and

[0013] FIG. 5 is a schematic diagram of a chiller of the climate control system of FIG. 1 according to some embodiments disclosed herein.DETAILED DESCRIPTION

[0014] A climate control system, such as a chiller system, may include a refrigerant circuit and one or more separate and additional fluid circuits for exchanging heat between an interior space and an ambient environment. For instance, the interior space may be one or more interior spaces of a building or other structure, and the ambient environment may be the outdoor environment at least partially surrounding the building. Specifically, a chiller system may include a fluid circuit that is configured to transfer heat between the refrigerant circuit and the interior space(s). The fluid circuit may circulate a heat transfer fluid in a substantially singular phase (e.g., a liquid phase) between a first heat exchanger positioned along the refrigerant circuit and a second heat exchanger that is configured to exchange heat between the heat transfer fluid and an airflow that is circulated through the interior space(s). Because this second heat exchanger is configured to transfer heat between the heat transfer fluid and an airflow, the assembly is commonly referred to as an “air handler.”

[0015] Conventional operational control over a chiller system, and particularly over an air handler of the chiller system has been lacking. Specifically, conventional approaches lack the ability to precisely control the rate of heat transfer between the heat transfer fluid and the airflow due to imperfect measurements (which may rely on averaging temperature sensors for the airflow 24 and / or averaging temperature sensors for the temperature of the coil 22), imprecise control systems, etc. As a result, the piping, pump(s), and other infrastructure for communicating the heat transfer fluid between the refrigerant circuit and air handler are often overdesigned to ensure that the air handler may be able to deliver a sufficient thermal capacity to the interior space(s) during operations. However, because chiller systems are typically useful for conditioning larger interior spaces, such as the interior spaces defined within office buildings, sports stadiums, data centers, retail spaces, manufacturing spaces, etc., even incremental capacity increases in a chiller system's infrastructure can significantly increase both the capital and operating costs.

[0016] Accordingly, embodiments disclosed herein provide systems and methods for more precise control of the operation a chiller system. Specifically, in some embodiments, an air handler of the chiller system may include a heat transfer coil (or “coil”) and one or more controllers that are configured to control the heat transfer rate in the coil by precisely controlling a flow rate of the heat transfer fluid therethrough based at least in part on a total temperature change for the heat transfer fluid across the coil. The control of the heat transfer rate may in turn be controlled based on one or more other performance metrics for the airflow also circulating through the air handler. Thus, control of the heat transfer rate of the coil in the air handler may be used as a proxy for controlling one or more other performance metric. Without being limited to this or any other theory, control of the heat transfer rate of the coil according to embodiments disclosed herein may provide a more precise and consistent method for adjusting the thermal capacity delivered to the interior space by the chiller system. As a result, this relatively precise control of the heat transfer rate through the coil may allow for enhanced thermal capacity performance from the air handler without necessitating increased infrastructure capacities (e.g., via larger piping diameters, more and / or larger pumps, etc.). Therefore, use of at least some embodiments disclosed herein may allow for enhanced operation and performance of existing chillers with minimal additional retrofit.

[0017] Referring now to FIG. 1, a climate control system 10 is shown according to some embodiments disclosed herein. The climate control system 10 includes a chiller 12, and thus, climate control system 10 may be referred to herein as a “chiller system”10. The chiller 12 may include or define a refrigerant circuit 14 that is configured to circulate a refrigerant between a pair of heat exchangers to transfer heat during operations. In some embodiments, the chiller 12 and refrigerant circuit 14 may be configured in the manner shown in FIG. 5 and described in more detail hereinafter.

[0018] The chiller system 10 may also include an air handler 20 and a heat transfer fluid circuit 15 (or “fluid circuit 15”) that is coupled to and between the air handler 20 and the chiller 12. The fluid circuit 15 may include a first line 17 that is configured to carry heat transfer fluid from the chiller 12 to the air handler 20, and a second line 16 that is configured to carry the heat transfer fluid from the air handler 20 back to the chiller 12. The lines 16, 17 may comprise pipes, hoses, conduit, channel, or any other suitable fluid conveyance member or system.

[0019] In some embodiments, the heat transfer fluid flowing in fluid circuit 15 may comprise water, such as substantially pure water, reverse osmosis water, or deionized water or an aqueous solution that includes water and one or more other constituents or additives. For instance, in some embodiments, the heat transfer fluid may comprise a water-glycol solution. Still other aqueous solutions are contemplated for the heat transfer fluid in fluid circuit 15 in various embodiments.

[0020] The air handler 20 may be a heat exchanger that is configured to transfer heat between the heat transfer fluid flowing in the fluid circuit 15 and an airflow 24. The air handler 20 may include a heat transfer coil 22 (or “coil”22) that is positioned along and therefore a part of the heat transfer fluid circuit 15. Specifically, the coil 22 may be coupled to both the first line 17 and second line 16 so that heat transfer fluid that is flowing to the air handler 20 along the first line 17 is flowed through the coil 22 and then is discharged into the second line 16 so it may return to the chiller 12 as previously described. The coil 22 may comprise a plurality of parallel fluid coils that are exposed to the airflow 24. The coil 22 has been represented in a relatively simple and schematic manner in FIG. 1 so as to simplify the drawings.

[0021] One or more pumps or other fluid conveyance devices may be included along the heat transfer fluid circuit 15, such as along one or both of the lines 17, 16. However, these additional features are not shown in FIG. 1 in order to simplify the drawings.

[0022] During operations, as the heat transfer fluid in the fluid circuit 15 is circulated through the coil 22, the airflow 24 is flowed over and around the outside of the coil 22 so that heat is transferred between the heat transfer fluid and the airflow 24 via the coil 22. The airflow 24 may then be emitted from the air handler 20 and flowed through an interior space 32 via ducting 30 so as to condition (e.g., heat, cool, dehumidify, etc.) the interior space 32. In some embodiments, the heat transfer fluid flowing in fluid circuit 15 may be maintained in a substantially liquid state as it circulates through and between the chiller 12 and air handler 20.

[0023] The ducting 30 may also return the airflow 24 back to the air handler 20 from the interior space 32. Specifically, the airflow 24 may flow from the interior space 32, through the ducting 30 to an inlet 26 of the air handler 20. Within the air handler 20, the airflow 24 may flow over and around the coil 22 to exchange heat with the heat transfer fluid of the fluid circuit 15 as previously described. Thereafter, the now conditioned airflow 24 may flow out of an outlet 28 of the air handler 20 and back into the interior space 32 via the ducting 30. Additional air 31 may be flowed into the air handler 20 from an outdoor or other ambient environment 33. This additional air 31 may be merged with the airflow 24 via the ducting 30, upstream or downstream of the inlet 26 of air handler 20.

[0024] One or more blowers or other air movers may be coupled to or along the ducting 30 in order to facilitate the flow of airflow 24 between the air handler 20 and interior space 32 during operations. In addition, the ducting may include additional dampers, valves, or other flow control devices that are configured to distribute the airflow 24 to multiple different outlets that flow into a single interior space 32 or multiple interior spaces 32. However, these additional features are not shown in FIG. 1 in order to simplify the drawings.

[0025] In some embodiments, the chiller system 10 may be configured to heat or cool the interior space 32 via the refrigerant circuit 14, the fluid circuit 15, and the airflow 24. Specifically, when the chiller system 10 is operating to cool the interior space 32 (so that the chiller system 10 is operating in a so-called “cooling mode”), the refrigerant circuit 14 may receive heat from the heat transfer fluid circulating in the fluid circuit 15. As a result, the heat transfer fluid discharged from the chiller 12 into the first line 17, may be cold or cool in temperature. The heat transfer fluid may then flow through the coil 22 so as to receive heat from the airflow 24 flowing through the air handler 20. This exchange of heat between the airflow 24 and heat transfer fluid via the coil 22 may cool the airflow 24 and heat the heat transfer fluid. In some embodiments, the temperature of the coil 22 may be less than a dewpoint temperature of the airflow 24 during the cooling mode operation, so that water may condense onto the coil 22. Thus, in some embodiments, the air handler 20 may include one or more pans or other collectors 27 that are configured to collect this condensation 29 and channel it to a drain or other collection point.

[0026] In some embodiments, the chiller system 10 may be configured to heat the interior space via the refrigerant circuit 14, the fluid circuit 15, and the airflow 24. Specifically, when the chiller system 10 is operating the heat the interior space (so that the chiller system 10 is operating in a so-called “heating mode”), the flow direction of the refrigerant circuit 14 may be reversed so that heat is transferred from the refrigerant to the heat transfer fluid flowing in the fluid circuit 15. Thus, in these embodiments, the heat transfer fluid flowing along the first line 17 to the air handler 20 may be hot or warm so that the airflow 24 is heated when it contacts the coil 22.

[0027] The chiller system 10 may also include a controller 50 that is configured to control one or more operational aspects thereof. For instance, as is described in more detail herein, the controller 50 may be configured to monitor and control the rate of heat transfer through the coil 22 of air handler 20 so as to ultimately affect one or more performance metrics of the airflow 24 during operations.

[0028] The controller 50 may be (or may be incorporated within) a main or master controller for the chiller system 10. Alternatively, the controller 50 may be a standalone controller 50 for controlling one or more aspects of the air handler 20. Regardless, the controller 50 may be described and referred to herein as being a part of the chiller system 10 according to at least some embodiments.

[0029] The controller 50 may comprise one or more computing devices, such as a computer, tablet, smartphone, server, circuit board, or other computing device(s) or system(s). Thus, controller 50 may include a processor 52 and a memory 54.

[0030] The processor 52 may include any suitable processing device or a collection of processing devices. In some embodiments, the processor 52 may include a microcontroller, central processing unit (CPU), graphics processing unit (GPU), timing controller (TCON), scaler unit, or some combination thereof. During operations, the processor 52 executes machine-readable instructions (such as machine-readable instructions 56) stored on memory 54, thereby causing the processor 52 to perform some or all of the actions attributed herein to the controller 50. In general, processor 52 fetches, decodes, and executes instructions (e.g., machine-readable instructions 56). In addition, processor 52 may also perform other actions, such as, making determinations, detecting conditions or values, etc., and communicating signals. If processor 52 assists another component in performing a function, then processor 52 may be said to cause the component to perform the function.

[0031] The memory 54 may be any suitable device or collection of devices for storing digital information including data and machine-readable instructions (such as machine-readable instructions 56). For instance, the memory 54 may comprise volatile storage (such as random-access memory (RAM)), non-volatile storage (e.g., flash storage, read-only memory (ROM), etc.), or combinations of both volatile and non-volatile storage. Data read or written by the processor 52 when executing machine-readable instructions 56 can also be stored on memory 54. Memory 54 may comprise or include a “non-transitory machine-readable medium,” where the term “non-transitory” does not include or encompass transitory propagating signals.

[0032] The processor 52 may include one processing device or a plurality of processing devices that are distributed within (or communicatively coupled to) controller 50 or more broadly within the chiller system 10. Likewise, the memory 54 may include one memory device or a plurality of memory devices that are distributed within (or communicatively coupled to) controller 50 or more broadly within the chiller system 10. Thus, the controller 50 may comprise a single controller or a plurality of individual “controllers” distributed throughout the chiller system 10 and that may be communicatively coupled to one another. Thus, the controller 50 may comprise “one or more” controllers, or “a plurality of” controllers. In some embodiments, the controller 50 may also comprise one or more “controllers” (including a processor and a memory as previously described) that are remotely positioned from the chiller system 10.

[0033] The controller 50 may be communicatively coupled to one or more sensors 36, 38, 40, 42, 44 that are configured to detect one or more operating parameters of the chiller system 10 of fluid flows associated therewith. As referred to herein, when a sensor (such as the sensors 36, 38, 40, 42, 44 or other sensors described herein) is said to detect a value, such “detection” would include any method by which the sensor may measure, estimate, compute, detect, etc. the value itself or some other value that is indicative thereof. Thus, no particular limitation is intended for the particular method by which a sensor “detects” a value (or value indicative thereof) unless otherwise stated.

[0034] The sensors 36, 38 may be configured to detect the temperature of the heat transfer fluid flowing in the lines 17, 16, respectively. Thus, the sensors 36, 38 may be referred to herein as “temperature sensors.” The temperature sensors 36, 38 may each comprise any suitable temperature sensing device, system, or arrays. For instance, the temperature sensors 36, 38 may comprise thermocouples, semiconductor-based temperature sensors, resistance temperature detectors (RTDs), thermistors, among others. Other temperature sensors described herein may also comprise any of these suitable temperature sensing devices, systems, or arrays.

[0035] The precise positioning and arrangement of the temperature sensors 36, 38 may be varied in different embodiments. For instance, in some embodiments, one or both of the temperature sensors 36 and 38 may not be positioned along the lines 17, 16, respectively, and may be positioned or integrated with the chiller 12 or the air handler 20 (such as on a port, body, or flow conduit on or defined by the chiller 12 or air handler 20). Thus, the indicated position of the temperature sensors 36, 38 along the lines 17, 16, respectively, is illustrative of only some embodiments. In some embodiments, the controller 50 may determine the temperature of the heat transfer fluid flowing to the air handler 20 via line 17 based on an output of a controller, sensor, or other device of the chiller 12. Thus, in one or more embodiments, the temperature sensors 36 and 38 may be omitted.

[0036] During operation, the controller 50 may receive outputs from the temperature sensors 36, 38 and a flow rate determined from the flow control device 34 to determine a heat transfer rate for the coil 22. Specifically, the controller 50 may determine the change in temperature of the heat transfer fluid across the coil 22 based on (or as) a difference between the temperatures of the heat transfer fluid in the lines 17, 16 as detected by the temperature sensors 36, 38, respectively. The change in temperature in the heat transfer fluid across the coil 22 may be characteristic or indicative of the heat transfer rate of the coil 22 during operations.

[0037] The controller 50 may also be communicatively coupled to a flow control device 34 positioned along or coupled to the first line 17, upstream or downstream of the coil 22. The controller 50 may adjust the flow control device 34 so as to precisely control the flow rate of heat transfer fluid through the coil 22 so as to control the heat transfer rate of the coil 22 during operations. In some embodiments, the heat transfer rate can vary based on the supply temperature 38. In these embodiments, the supply temperature 38 is controlled by the chiller 12.

[0038] In some embodiments, the flow control device 34 may comprise any suitable valve or valve system for controlling the flow rate of heat transfer fluid through the coil 22. For instance, the control valve 34 may comprise a pressure-independent flow control device (e.g., a pressure-independent metering control valve), such as those described in U.S. Pat. No. 10,036,568, the contents of which being incorporated by reference. Specifically, the control valve 34 may include a valve (or orifice), and a pilot-operated pressure regulator. The pilot-operated pressure regulator is configured to maintain a fixed pressure differential across the control valve. Thus, regardless of the pressure of the heat transfer fluid flowing along the line 17, the flow control device 34 may be configured to achieve and maintain a particular flow rate of heat transfer fluid therethrough, constituting a metering control valve.

[0039] It should be appreciated that the flow control device 34 may include additional or alternative flow control devices, other than a control valve as previously described. For instance, in some embodiments, the flow control device 34 may comprise a pump, such as a variable speed pump that is configured to selectively alter the pressure and flow rate of the heat transfer fluid discharged therefrom. Thus, configuring the flow control device 34 as a control valve as previously described is only illustrative of some embodiments.

[0040] During operations, the controller 50 may adjust a position or operational state of the flow control device 34 so as to achieve or maintain a desired heat transfer rate in the coil 22 as indicated by outputs from the temperature sensors 36, 38. In some embodiments, the controller 50 may adjust the heat transfer rate of the coil 22 via adjustments to the flow control device 34 based on one or more other measurements or flow parameters associated with the air handler 20. For instance, the controller 50 may control the heat transfer rate of the coil 22 based on one or more parameters associated with the airflow 24 flowing through, to, or from the air handler 20.

[0041] In some embodiments, the chiller system 10 may include additional sensors 40, 42 that are coupled to one or more of the air handler 20 and the ducting 30. In some embodiments, the sensor 40 may be coupled to the outlet 24 of air handler 20, and the sensor 42 may be coupled to the inlet 24 of air handler 20. The sensor 42 may be configured to detect one or more parameters of the airflow 24, upstream of the coil 22, and the sensor 40 may be configured to detect one or more parameters of the airflow 24, downstream of the coil 22. For example, in some embodiments, the sensor 40 may detect a temperature, a relative humidity, or both of the airflow 24 downstream of the coil 22, and the sensor 42 may detect a temperature, a relative humidity of both of the airflow 24 upstream of the coil 22. In some embodiments, the controller 50 may be communicatively coupled to an additional sensor 44 that is configured to detect one or more parameters of the ambient environmental airflow 33. Thus, while the sensors 40, 42, 44 are represented as singular sensors in FIG. 1, it should be appreciated that one or more of the sensors 40, 42, 44 may be multiple sensors (such as a sensor array) that is configured to detect multiple parameters or values.

[0042] During operations, the controller 50 may control the heat transfer rate of the coil 22, via adjustment to the flow rate of heat transfer fluid through coil 22 via flow control device 34 based on one or more other parameters of or relating to the airflow 24, such as determined via outputs from one or more of the additional sensors 40, 42, 44. More specifically, the controller 50 may set or receive a first target value for a parameter of or relating to the airflow 24, and then may set a second target value for the heat transfer rate through the coil 22 (or value indicative thereof such as flow rate through coil 22) based on the first target value. Thus, the controller 50 may apply a cascaded control scheme whereby the heat transfer rate through the coil 22 is controlled as a proxy to achieve a desired value (e.g., the first target value) of the one or more other parameters of or relating to the airflow 24.

[0043] Without being limited to this or any other theory, the flow control device 34 and temperature sensors 36, 38 provide a precise system for controlling the heat transfer rate through the coil 22 during operations. Specifically, the flow control device 34 is effective for controlling a total flow rate of the heat transfer fluid within relatively tight limits, and the temperature sensors 36, 38 are configured to more effectively measure a representative temperature differential of the heat transfer fluid as it travels through a more confined space (e.g., the lines 17, 16). As a result, by basing control of the one or more other parameters of the airflow 24 on the rate of heat transfer through the coil 22, a finer level of control is achievable so that additional capacities can be reliably achieved from the chiller system 10 and its existing infrastructure as previously described.

[0044] Referring now to FIG. 2, a flow chart of the control logic employed by the controller 50 for controlling the heat transfer rate of the air handler 20 of chiller system 10 is shown according to some embodiments. In the following description of the flow chart of FIG. 2, continuing reference will be made to the chiller system 10 of FIG. 1. However, it should be appreciated that embodiments of the control logic illustrated in the flow chart of FIG. 2 may be utilized to control the heat transfer rate of an air handler of another climate control system that is different from the chiller system 10 shown in FIG. 1 in at least some respects. In some embodiments, the chiller system 10 can be a district cooling system or another type of an interposing heat exchanger (e.g., a heat exchanger used to isolate a floor of a building), or another type of chiller. The control logic shown in FIG. 2 may be representative of at least some of the machine-readable instructions 56 stored on memory 54 and executed by processor 52 of controller 50 in FIG. 1 (or of another controller as noted herein).

[0045] Initially, a user 60 may select a value for a desired climate parameter at block 62. The user 60 may be, for example, an occupant of the interior space 32 (FIG. 1), a technician, or other personnel for the building defining the interior space 32. The user 60 may input the desired climate parameter of block 62 directly to the controller 50 or to another controller or other suitable user input device, such as a thermostat or software application running on another computing device such as a computer, tablet, or smartphone, etc. In some embodiments, the value for the desired climate parameter of block 62 may be determined by the controller 50 or another controller based on some other input, stimulus, measurement, operating mode of chiller system 10, etc.

[0046] In some embodiments, the desired climate parameter in block 62 may be any suitable climate parameter that describes the state or condition of the climate within the interior space 32 (FIG. 1). For instance, in some embodiments, the desired climate parameter in block 62 may comprise a desired temperature, a desired relative humidity, or some combination thereof.

[0047] The controller 50 (or another controller of or communicatively coupled to chiller system 10) may set a target airflow performance metric (a “first target”) for the airflow 24 at block 64. The target airflow performance metric at block 64 may be selected to correspond with the desired climate parameter of block 62 so that achieving the target airflow performance metric set at block 64 will provide the desired climate parameter of block 62 to the interior space 32. For instance, when the climate parameter of block 62 is a desired or set point temperature for the interior space 32, the target airflow performance metric set at block 64 may comprise a target temperature, such as a target dry bulb temperature, for the airflow 24 discharged from the air handler 20 that is configured to achieve the set point temperature in the interior space 32. Conversely, when the desired climate parameter of block 62 is a desired relative humidity for the interior space 32, the target airflow performance metric set at block 64 may comprise a target relative humidity or a target dewpoint temperature for airflow 24 discharged from the air handler 20 that is configured to achieve the desired relative humidity for the interior space 32.

[0048] After the target airflow performance metric is set at block 64, the controller 50 may then set a target heat transfer rate through the coil 22 of the air handler 20 at block 66. In some embodiments, the target heat transfer rate in block 66 is at least partially based on the target airflow performance metric from block 64. As previously described, the heat transfer rate of the coil 22 may be more precisely monitored and controlled via flow control device 34 and sensors 36, 38 than other parameters associated with the airflow 24. In addition, the air flow performance metric (such as temperature, relative humidity, or both) for the airflow 24 may be at least partially based on the rate of heat transfer between the heat transfer fluid and airflow 24 via coil 22. As a result, the target airflow performance metric from block 64 is essentially converted to a target heat transfer rate of the coil 22 via block 66 that is more precisely monitored and adjusted by the controller 50 during operations.

[0049] Once the target heat transfer rate of the coil 22 is set at block 66, the controller 50 may be adjust the flow rate of the heat transfer fluid through the coil 22 via the flow control device 34 at block 68 to achieve (or maintain) the target heat transfer rate based on feedback received from the temperature sensors 36, 38 and 34 (fluid flow rate). Specifically, in some embodiments, the controller 50 may determine an error between the current heat transfer rate of the coil 22 and the target heat transfer rate set at block 66 via outputs from the temperature sensors 36, 38 and from liquid flow rate 34. Then, the controller 50 may adjust a flow rate of the heat transfer fluid through the coil 22 via the flow control device 34 in order to reduce or eliminate the error. In some embodiments, the controller 50 may apply a proportional, integral, derivative (PID) control scheme for reducing the error of the heat transfer rate of the coil 22 via adjustments to the flow control device 34 or may apply some other control logic (such as anyone or more of the proportional, integral, derivative controls).

[0050] In some embodiments, the control logic of FIG. 2 may include a feedback from block 68 to block 64 in order to update the targets for the airflow performance metric and heat transfer rate of the coil 22 as appropriate. For instance, as the error in the airflow performance metric is reduced, the targets for one or both of the airflow performance metric and the heat transfer rate of coil 22 may be updated to slow a rate of change of the heat transfer rate of coil 22 and airflow performance metric in order to avoid overshoot, or inefficient operation of the chiller system 10.

[0051] In some embodiments, another controller (that is different from the controller 50) may carry out block 64, and then may communicate the target airflow performance metric to the controller 50, which may then carry out blocks 66 and 68 as previously described. In some embodiments, the other controller may carry out both blocks 64 and 66, and then may communicate either target heat transfer rate of the coil 22 to the controller 50 which then carries out block 68 to reduce the error as previously described. Still other combinations of controllers (such as controller 50 alone or in combination with other controllers) for carrying out the control logic of FIG. 2 are contemplated for various embodiments.

[0052] In some embodiments, the controller 50 (or another controller as previously described) may set the target heat transfer rate for the coil 22 based on an error in the target airflow performance metric at block 64. Specifically, if the current airflow performance metric is far from the target set at block 64 (so that the error in the airflow performance metric is large), the target heat transfer rate of the coil 22 may be set more aggressively in order to more quickly reduce the error of the airflow performance metric. Thus, in some embodiments, the target heat transfer rate for the coil 22 may be set at block 66 based at least in part on the current error in the airflow performance metric relative to the target set at block 64.

[0053] In some embodiments, the precise control of the heat transfer rate of the coil 22 via the controller 50 may unlock additional heat transfer from the heat transfer fluid of fluid circuit 15 that would not otherwise be reliably achieved via conventional control methods. For instance, by precisely controlling the heat transfer rate of the coil 22, a greater temperature change in the heat transfer fluid can be reliably achieved and maintained during operation by use of the existing infrastructure of the chiller system 10. In some instances, a conventional chiller control may aim to reliably achieve about a 30 or more ° F. temperature rise for the heat transfer fluid across the coil 22 during a cooling mode operation of the chiller system. Moreover, the chiller system may be generally overdesigned (e.g., such as via larger piping sizes for the fluid circuit 15, standard pressure dependent control valves, imprecise valve operator / positioners, larger pumps, etc.) so as to overflow the heat transfer fluid through the coil 22 in order to reliable achieve this modest temperature rise in light of the less precise conventional methods of control based solely on parameters related to the airflow 24. However, when the more precise control described herein that is based on the heat transfer rate of the coil 22 as determined via the sensors 36, 38 and flow control device 34, the flow rate of the fluid circuit 15 of existing chillers may be optimized / minimized to reliable achieve much greater temperature rises in the heat transfer fluid of fluid circuit 15. For example, in some embodiments, by use of the more precise control methods described herein, the heat transfer fluid flowing in fluid circuit 15 may reliably achieve temperature rises of about 30° F. or more during a cooling mode operation of the chiller system 10. This additional thermal heat transfer in the air handler 20 can, in turn, lead to more efficient operation of the chiller system 10 overall and may help to avoid costly upgrades (including the addition of more chillers 12).

[0054] Some specific examples of the control logic of FIG. 2 are now described for the chiller system 10 of FIG. 1 in order to further illustrate some specific embodiments. These specific examples illustrate the operation of control logic of FIG. 2 with respect to the specific climate parameters for the interior space 32 and specific target airflow performance metrics (block 64). However, these specific examples are merely illustrative of some embodiments and are not meant to limit other potential implementations of the control logic in FIG. 2. In describing these specific examples, continuing reference will be made to the chiller system 10 of FIG. 1 and the example control logic of FIG. 2.

[0055] For example, in some embodiments the desired climate parameter in block 62 of FIG. 2 may comprise a desired temperature of the interior space 32 (FIG. 1). As a result, the target airflow performance metric set at block64 may comprise a temperature of the airflow 24 that is discharged from the air handler 20 to the interior space 32 via ducting 30. In some embodiments, the target airflow temperature may be equal to or more likely less than the desired climate parameter in block 62 of FIG. 2. Specifically, as would be appreciated by one having ordinary skill in the art, a target airflow temperature for reducing a temperature of an interior space (such as interior space 32) may be generally lower than the desired or set point temperature for the interior space so that the desired temperature may be achieved after a reasonable period of operating time.

[0056] In some embodiments, the temperature of the airflow 24 in the outlet 28 or in the ducting 30, downstream of the air handler 20 may be detected via the temperature sensor 40. In some embodiments, the temperature sensor 40 may comprise a probe that extends into the outlet 28 or the ducting 30 downstream of air handler 20 in order to sample and measure the temperature of the airflow 24. In some embodiments, the sensor 40 may measure the dry bulb temperature of the airflow 24.

[0057] Once the target airflow temperature is set or received as the target airflow performance metric at block 64 (FIG. 2), the controller 50 (or another controller as previously described) may then set the target heat transfer rate for the coil 22 (e.g., block 66 in FIG. 2) based on the target temperature of the airflow 24 discharged from the air handler 20 or the error in the temperature of the airflow 24 relative to the target via outputs form the temperature sensor 40 as previously described. In addition, the controller 50 may adjust the flow rate of heat transfer fluid through the coil 22 via adjustments to the flow control device 34 to reduce an error in the heat transfer rate in the coil 22 relative to the target value as informed by the temperature sensors 36, 38 and flow control valve flow rate as previously described. As is also previously described, the controller 50 may adjust the target heat transfer rate of the coil 22 as an error associated with the temperature of the airflow 24 discharged from the air handler 20 is reduced relative to its target (e.g., the target airflow performance metric of block 64 in FIG. 2). Thus, in this example, the controller 50 may achieve and maintain the target discharge temperature of the airflow 24 via the more precise control of the heat transfer rate through the coil 22.

[0058] In some embodiments, one or more target values applied by the controller 50, such as the target dry bulb temperature of the airflow 24 discharged from the air handler as previously described, may be modified or updated based on additional temperatures (or other values) associated with the chiller system 10. For instance, in some embodiments, the temperature of an outer surface of the ducting 30 downstream of the air handler 20 may be detected by the sensor 40 (or another sensor) during operations and compared to a dewpoint temperature for an environment surrounding the ducting 30. If the temperature of the outer surface of the ducting 30 is equal to or less than the dewpoint temperature of this surrounding environment, moisture may condense out of the surrounding environment onto the outer surface of the ducting 30, which thereby may lead to mold, mildew, or other undesirable organic growth. As a result, during operations, the controller 50 may update one or both of the target values associated with the dry bulb temperature for the airflow 24 discharged from air handler 20 and the heat transfer rate of the coil 22 in order to avoid condensing moisture on an outer surface of the ducting 30. Specifically, the controller 50 may increase the target value for the dry bulb temperature of the airflow 24 downstream of the coil 22 and / or may decrease the target heat transfer rate of the coil 22 in order the maintain the temperature of the outer surface of the ducting 30 above the dewpoint temperature of the surrounding environment. In some embodiments, with the controller 50 updating the dry bulb temperatures of the airflow 24 using data from sensor 40,the target of the temperature of the airflow 24 downstream of the coil 22 in a sensible cooling regime may allow a fan or blower that is generating the airflow 24 to be operated at a relatively lower speed and this may increase the overall operating efficiency for the chiller system 10.

[0059] In some embodiments, the desired climate parameter in block 62 of FIG. 2 may comprise a desired relative humidity (or an indicative or related value) of the interior space 32 (FIG. 1). As a result, the target airflow performance metric set at block 64 (by controller 50 or another controller as previously described) may comprise a relative humidity (or other related value such as a dewpoint temperature) of the airflow 24 that is discharged from the air handler 20 to the interior space 32 or the return air from ducting 30.

[0060] In some embodiments, the target airflow performance metric set at block 64 of FIG. 2 for reducing a relative humidity of the interior space 32 may comprise target operating temperature for the coil 22 that is at or below a dewpoint temperature of the airflow 24 downstream of the coil 22 of air handler 20. Without being limited to this or any other theory, the dewpoint temperature of a volume of air (such as airflow 24) is the temperature at which moisture begins to condense out of that volume of air. Thus, for the chiller system 10, if the temperature of the coil 22 were lowered to or below the dewpoint temperature of the airflow 24, moisture will begin to condense out of the airflow 24 onto the coil 22 as the airflow 24 passes through the air handler 20. While a reduction of the temperature of coil 22 below the dewpoint temperature of the incoming airflow 24 will result in a more rapid condensation of moisture (and therefore a more rapid reduction of the relative humidity of the airflow 24 delivered to interior space 32), every degree of incremental reduction in temperature of the coil 22 comes at the cost of additional thermal capacity delivered from the chiller 12, which reduces the operating efficiency of the chiller system 10.

[0061] Accordingly, it would be most efficient to precisely maintain the operating temperature of the coil 22 at or just below the dewpoint temperature setpoint in order to reduce a moisture content of the airflow 24, while avoiding the operating inefficiencies associated with overcooling the coil 22. Conventional control schemes for an air handler lack the precision that would allow for such precise control of the coil 22 at the dewpoint temperature during operations. However, because the operating temperature of the coil 22 is a function of the heat transfer rate through the coil 22, the controller 50 may apply the precise control scheme of heat transfer rate via the flow control device 34 and temperature sensors 36, 38 as previously described, in order to achieve or maintain the operating temperature of the coil 22 at or just below the dewpoint temperature to provide dehumidification for the airflow 24 while maintaining maximum operation efficiency for chiller system 10.

[0062] During operations, the controller 50 (or another controller as previously described) may receive outputs from one or more sensors, such as sensor 42, in order to determine the dewpoint temperature of the airflow 24, upstream of the coil 22. For instance, in some embodiments, the sensor 42 may comprise a suitable sensor or array of sensors for detecting the dewpoint temperature of the airflow 24 (or one or more values indicative thereof). For instance, the sensor 42 may comprise a temperature sensor that is configured to measure a dry bulb temperature of the airflow 24 upstream of the coil 22, and a humidity sensor that is configured to measure a relative humidity of the airflow 24 upstream of the coil 22. The temperature and the relative humidity of the airflow 24 may, in turn be used to compute the dewpoint temperature. In some embodiments, the sensor 42 may determine one of the temperatures of relative humidity of the airflow, while additional sensors, such as sensors positioned in the interior space 32, may determine the other of the temperature or relative humidity of the airflow 24. In some embodiments, the controller 50 may determine the dewpoint temperature of the airflow 24 based on both temperature and relative humidity measurements taken by use of sensors positioned in the interior space 32. In some embodiments, the sensor 42 (or another sensor) may comprise a hygrometer or other suitable sensor for more directly determining the dewpoint temperature of the airflow 24.

[0063] Once the dewpoint temperature of the airflow upstream of the coil 22 is determined, the dewpoint temperature may be used to select an appropriate target dewpoint temperature for the coil 22 as the target airflow performance metric in block 64 of FIG. 2. The dewpoint temperature of the coil 22 may comprise an average dewpoint temperature of the coil 22 that may be computed based on the dewpoint temperature change across the coil 22 via outputs from the temperature sensors 36, 38. In some embodiments, the target dewpoint temperature of the coil 22 may be equal to or at least based on the dewpoint temperature of the airflow 24 upstream of the coil 22. For instance, in some embodiments, the target dewpoint temperature of the coil 22 may be less than the dewpoint temperature by a pre-determined offset, such as 1° F., 2° F., 5° F., etc. to ensure that a majority of the coil 22 surface may be below the dewpoint temperature during operations.

[0064] In some embodiments, the controller 50 may set or receive a target dewpoint temperature for the airflow discharged from the air handler 20 and may control the heat transfer rate through the coil 22 based at least in part on the target dewpoint temperature. Specifically, the controller 50 may set or receive a target dewpoint for the airflow 24 downstream of the coil 22 based on a desired relative humidity for the interior space (e.g., as a desired climate parameter in box 62 of FIG. 2). A sensor (such the sensor 40) may detect one or more variables, such as temperature and relative humidity, of the airflow 24 downstream of the coil 22 that may be used by the controller 50 to determine an error between the current dewpoint of airflow 24 downstream of the coil 22 and the target dewpoint. This error may then be used to determine a target heat transfer rate of the coil 22 that may then drive the dewpoint temperature of the airflow 24 toward the target dewpoint temperature.

[0065] In some embodiments, the controller 50 may set a target value for the heat transfer rate of the coil 22 based on a plurality of climate parameters (and associated airflow performance metrics) associated with the interior space 32. For instance, in some embodiments, a user may input both a desired temperature and / or a desired relative humidity as desired climate parameters for the interior space 32 (block 62 in FIG. 2). In response, the controller 50 may monitor the values of the temperature and relative humidity of the airflow 24 upstream of the coil 22 (or within the interior space 32 as previously described). When the relative humidity (or dewpoint temperature as previously described) is below a threshold or target value (which may correspond to a target airflow performance metric in block 64 of FIG. 2), the controller 50 may select the target heat transfer rate through the coil 22 to provide a target dry bulb temperature of the airflow 24 downstream of coil 22 as previously described. Thus, the controller 50 may control the heat transfer rate of the coil 22 in order to achieve and maintain multiple desired climate parameters for the interior space (block 62 in FIG. 2) during operations.

[0066] In some embodiments, when the relative humidity of the airflow 24 downstream of the coil 22 is below a threshold and the controller 50 is controlling the heat transfer rate of the coil 22 to achieve a desired dry bulb temperature of the airflow 24 downstream of the coil 22 as previously described, the controller 50 may further control the heat transfer rate of the coil 22 to achieve a relatively low target temperature for the airflow 24 downstream of coil 22. Specifically, when relative humidity of the airflow 24 is within a desired or acceptable range, the air handler 20 is primarily operating to perform sensible cooling (or primarily sensible cooling) of the airflow 24. As a result, reducing a target of the temperature of the airflow 24 downstream of the coil 22 in a sensible cooling regime may allow a fan or blower that is generating the airflow 24 to be operated at a relatively lower speed, which may increase the overall operating efficiency for the chiller system 10.

[0067] Referring now to FIG. 3, in some embodiments, the chiller system 10 may include a plurality of chillers 12 that circulate heat transfer fluid through a plurality of air handlers 20 for cooling a plurality of interior spaces 32 within a larger building or complex 70. In some of these embodiments, the chillers 12 may circulate the heat transfer fluid to a particular air handler 20, a subset of the air handlers 20, or all of the air handlers 20. For instance, in some embodiments, all or a subset of the chillers 12 may discharge heat transfer fluid to a line or manifold that the distributes the heat transfer fluid through one, a subset, or all of the air handlers 20 during operations.

[0068] The chiller system 10 may include one or more controllers 50 (collectively shown as a controller 50 in FIG. 3that are configured to adjust a position of one or more flow control devices 34 that are upstream of each of (or a subset of) the air handlers 20, so as to control a flow rate of the heat transfer fluid through the coils 22 of the air handlers 20 as previously described. Thus, during operations, the controller(s) 50 may set a target heat transfer rate through the coils 22 of the corresponding air handlers 20 based on target values for one or more airflow performance metrics associated with the airflow (such as a temperature, relative humidity, dewpoint temperature, etc.), that is in turn based on a desired climate parameter for the corresponding indoor space 32 as previously described. In some embodiments, each air handler 20 may include a separate controller 50 that is configured to control the corresponding flow control device 34 as previously described. Alternatively, in some embodiments a plurality of the air handlers 20 (including a subset of the air handlers 20 or all of the air handlers 20) may have a single controller 50 that controls the flow rate though each of the plurality of air handlers 20 as previously described.

[0069] Referring now to FIG. 4, a method for controlling a climate control system is shown according to some embodiments. The method 100 may be performed by use of embodiments of the chiller system 10, but it should be appreciated that the method 100 may be performed by use of other climate control systems that are different from one or more embodiments of the chiller system 10 in at least some respects. Thus, in describing the method 100, continuing reference will be made to the chiller system 10 shown in FIG. 1 and the control logic of FIG. 2.

[0070] In addition, the method 100 may be at least partially performed by a processor of a controller, such as the processor 52 of controller 50 in FIG. 1. Thus, the method 100 may be at least partially illustrative of embodiments of the machine-readable instructions 56 stored on the memory 54.

[0071] Initially, the method 100 includes setting a first target for a performance metric for an airflow through an air handler of a climate control system at block 102. For instance, as previously described for the control logic of FIG. 2, a first target for a performance metric of or relating to the airflow 24 through the air handler 20 may be set based on a desired climate parameter for the interior space 32. In some embodiments, the desired climate parameter for the interior space 32 may be a desired temperature or relative humidity, and the corresponding first target for the performance metric in block 102 may comprise a suitable target for achieving the desired climate parameter, such as a target dry bulb temperature, relative humidity, dewpoint temperature, etc. of the airflow 24, such as the airflow leaving the air handler 20.

[0072] In addition, the method 100 includes setting a second target for a heat transfer rate for a coil of the air handler based on the first target at block 104 and adjusting a flow rate of heat transfer fluid through the coil to reduce an error associated with the second target at block 106. For instance, as previously described for the chiller system 10, the controller 50 may set a target for the heat transfer rate through coil 22 that is configured to achieve the target for the air performance metric. Thus, as previously described, because the controller 50 may control the heat transfer rate through the coil 22 more precisely than other parameters associated with the air handler 20, the controller 50 may control the heat transfer rate of the coil 22 as a proxy for achieving the target airflow performance metric.

[0073] Referring now to FIG. 1, a schematic representation of an embodiment of a chiller 12 of the chiller system 10 of FIG. 1 is shown according to some embodiments disclosed herein. As previously described, the chiller 12 includes a refrigeration circuit 14 that is configured to circulate a refrigerant to exchange heat between the interior space(s) 32 of the building and the ambient environment 33 (e.g., such as the outdoor environment that surrounds the building defining the interior space(s) 32). The refrigeration circuit 14 may include a first heat exchanger 222 and a second heat exchanger 224. The first heat exchanger 222 is configured to exchange heat between the refrigerant and a working fluid 244 of an ambient heat exchange assembly 242, and the second heat exchanger 224 is configured to exchange heat between the refrigerant and the heat transfer fluid flowing in heat transfer fluid circuit 15 as previously described.

[0074] As previously described, the heat transfer fluid may circulate along the heat transfer fluid circuit 15 between the second heat exchanger 224 of the refrigeration circuit 14 and the air handler 20 to exchange heat between the interior space(s) 32 and the refrigerant. Likewise, the working fluid 244 may circulate between the first heat exchanger 222 of the refrigeration circuit 14 and the ambient heat exchange assembly 242 to exchange heat between the refrigerant and the ambient environment 33.

[0075] In some embodiments, the ambient heat exchange assembly 242 comprises one or more heat exchangers (e.g., water cooling towers, radiators, fin-fan coolers, etc.) that are configured to transfer heat between the ambient environment 33 and the working fluid 244. In some embodiments, such as in the case of air-cooled chillers (described in more detail hereinafter), the ambient heat exchange assembly 242 may be integrated and combined with the first heat exchanger 222 so that heat is directly exchanged between the refrigerant and an airflow that is sourced from and provided back to the ambient environment.

[0076] The working fluid 244 may be similar to the heat transfer fluid flowing along fluid circuit 15. Thus, the working fluid 244 may comprise water or any other suitable aqueous mixture, such as a water-glycol mixture. Alternatively, the working fluid 244 may comprise air. When the working fluid 244 is water (or another aqueous mixture), the chiller 12 may be referred to as a “water-cooled” chiller, and when the working fluid 244 is air, the chiller 12 may be referred to as an “air-cooled” chiller.

[0077] In addition to the first heat exchanger 222 and the second heat exchanger 224, the refrigeration circuit 14 may include a compressor 226 (or one or more compressors 226 in some embodiments) and an expansion valve 230. The compressor 226 and expansion valve 230 may be in fluid communication with the first heat exchanger 222 and second heat exchanger 224 along the refrigerant circuit 14. During operations, the refrigeration circuit 14 may be operated to circulate the refrigerant in a first direction shown in FIG. 1 so as to transfer heat from the interior space(s) 32 to the ambient environment 33 (e.g., via the ambient heat exchange assembly 242). Such operation may be referred to herein as a “cooling mode” operation.

[0078] Specifically, in the cooling mode operation shown in FIG. 5, the refrigerant (which may be in a vapor or semi-vapor state) may be compressed by the compressor 226 and delivered to the first heat exchanger 222 via the refrigerant circuit 14. Within the first heat exchanger 222, heat is transferred from the refrigerant to the working fluid 244, which cools the refrigerant and at least partially condenses the refrigerant to a liquid. Thus, in the cooling mode operation of FIG. 5, the first heat exchanger 222 may be referred to as a “condenser.” Heat is then transferred from the heated working fluid 244 to the ambient environment 33 via the ambient heat exchange assembly 242 as previously described.

[0079] The condensed refrigerant is then expelled from the first heat exchanger 222 and flowed to the second heat exchanger 224 via the expansion valve 230. The expansion valve 230 may be positioned between the first heat exchanger 222 and second heat exchanger 224 along the refrigerant circuit 14. The expansion valve 230 may be actuated or configured so as to controllably expand and therefore cool the refrigerant upstream of the second heat exchanger 224.

[0080] The expanded and cooled refrigerant is then flowed to the second heat exchanger 224. Within the second heat exchanger 224, heat is transferred from the heat transfer fluid flowing along fluid circuit 15 to the refrigerant, which vaporizes (or at least partially vaporizes) the refrigerant. Thus, in the cooling mode operation of FIG. 5, the second heat exchanger 224 may be referred to as an “evaporator.” The cooled heat transfer fluid is then circulated to the air handler 20 to cool the interior space(s) 32 as previously described.

[0081] While not shown, in some embodiments, the refrigeration circuit 14 may circulate the refrigerant in a second, opposite direction than that shown in FIG. 5 so as to transfer heat from the ambient environment 33 to the interior space(s) 32 via the ambient heat exchange assembly 242 and the fluid circuit 15. Such operation may be referred to herein as a “heating mode” operation, and a refrigeration circuit 14 that is configured to operate in the heating mode may be referred to as a “heat pump.” During a heating mode operation of the refrigeration circuit 14, the first heat exchanger 222 may function as an “evaporator” (which vaporizes the refrigerant) and the second heat exchanger 224 may function as a “condenser” (which condenses the refrigerant).

[0082] The operation of the chiller 12 may be adjusted so as to provide different output cooling (or heating) capacities to the heat transfer fluid of the fluid circuit 15 during operations. Specifically, the mass flow rate of refrigerant flowing along the refrigerant circuit 14 may be adjusted (e.g., via adjustments to the operating speed of the compressor 226 and corresponding adjustments to the opening position of the expansion valve 230) to thereby change the rate of thermal heat transfer between the refrigerant and the heat transfer fluid of fluid circuit 15. In some embodiments, the chiller 12 may be operated at a lower output cooling capacity (e.g., by lowering the speed of the compressor 226) when the cooling demands of the interior space(s) 32 are lower.

[0083] As explained above and reiterated below, the present disclosure includes, without limitation, the following example implementations.

[0084] Clause 1. A method of controlling a climate control system, the method includes (a) setting a first target for a performance metric for an airflow through an air handler of a climate control system, (b) setting a second target for a heat transfer rate for a coil of the air handler based on the first target, and (c) adjusting a flow rate of heat transfer fluid through the coil to reduce an error associated with the second target.

[0085] Clause 2. The method of clause 1, wherein the performance metric comprises a temperature associated with the airflow.

[0086] Clause 3. The method of clause 2, wherein (a) comprises setting the first target for a dry bulb temperature of the airflow leaving the air handler.

[0087] Clause 4. The method of clause 2, wherein (a) comprises setting the first target for a temperature of ducting that receives the airflow from the air handler.

[0088] Clause 5. The method of clause 4, wherein (a) comprises setting the first target above a dewpoint of air surrounding an outside of the ducting.

[0089] Clause 6. The method of clause 2, wherein (c) comprises:

[0090] (c1) increasing the flow rate of the heat transfer fluid through the coil to increase the heat transfer rate through the coil and thereby decrease the temperature associated with the airflow; or

[0091] (c2) decreasing the flow rate of the heat transfer fluid through the coil to decrease the heat transfer rate through the coil and thereby increase the temperature associated with the airflow.

[0092] Clause 7. The method of clause 1, wherein the performance metric comprises a relative humidity of the airflow upstream of the air handler.

[0093] Clause 8. The method of clause 7, wherein (a) comprises setting the first target at or below a dewpoint temperature of the airflow upstream of the air handler.

[0094] Clause 9. A climate control system for conditioning an interior space, the climate control system includes a chiller that is configured to exchange heat with a flow of heat transfer fluid, an air handler including a coil that is configured to receive the flow of heat transfer fluid therethrough, ducting coupled to the air handler that is configured to circulate an airflow between the interior space and the air handler, and one or more controllers that are configured to: set a first target for a performance metric for the airflow based on a desired climate parameter for the interior space; set a second target for a heat transfer rate for the coil of the air handler based on the first target; and adjust a flow rate of heat transfer fluid through the coil to reduce an error associated with the second target.

[0095] Clause 10. The climate control system of clause 9, further including a first temperature sensor that is configured to detect a temperature of the heat transfer fluid emitted from the coil, wherein the one or more controllers are configured to determine the heat transfer rate for the coil based at least in part on an output from the first temperature sensor.

[0096] Clause 11. The climate control system of clause 10, further including a valve coupled between the chiller and the coil of the air handler, wherein the one or more controllers are configured to adjust the flow rate of the heat transfer fluid through the coil by adjusting a position of the valve.

[0097] Clause 12. The climate control system of clause 11, further including a second temperature sensor that is configured to detect a temperature of the airflow discharged from the air handler, wherein the one or more controllers are configured to set the first target for the performance metric as a target for the temperature of the airflow discharged from the air handler.

[0098] Clause 13. The climate control system of clause 11, further including a third temperature sensor that is configured to detect a temperature of the ducting downstream of the air handler, wherein the one or more controllers are configured to set the first target for the performance metric as a target for the temperature of the ducting downstream of the air handler.

[0099] Clause 14. The climate control system of clause 13, wherein the one or more controllers are configured to set the first target so that the temperature of the ducting downstream of the air handler is maintained above a dewpoint for air surrounding an outside of the ducting.

[0100] Clause 15. The climate control system of clause 11, further including a humidity sensor that is configured to detect a relative humidity of the airflow upstream of the air handler, wherein the one or more controllers are configured to set the first target as a temperature of the airflow that is at or below a dewpoint temperature of the airflow based at least in part on an output from the humidity sensor.

[0101] Clause 16. The climate control system of clause 11, wherein the one or more controllers are further configured to:

[0102] increasing the flow rate of the heat transfer fluid through the coil to increase the heat transfer rate through the coil and thereby decrease the temperature associated with the airflow; or

[0103] decreasing the flow rate of the heat transfer fluid through the coil to decrease the heat transfer rate through the coil and thereby increase the temperature associated with the airflow.

[0104] Clause 17. The climate control system of clause 11, wherein the performance metric comprises a relative humidity of the airflow upstream of the air handler.

[0105] Clause 18. The climate control system of clause 9, wherein the one or more controllers are further configured to:

[0106] setting the first target at or below a dewpoint temperature of the airflow upstream of the air handler.

[0107] Clause 19. A non-transitory, machine-readable medium comprising instructions, which when executed by one or more processors, cause the one or more processors to:

[0108] (a) set a first target for a performance metric for an airflow through an air handler of a climate control system; (b) set a second target for a heat transfer rate for a coil of the air handler based on the first target; and (c) adjust a flow rate of heat transfer fluid through the coil to reduce an error associated with the second target.

[0109] Clause 20. The non-transitory, machine-readable medium of clause 19, wherein the performance metric comprises a temperature associated with the airflow.

[0110] Clause 21. The non-transitory, machine-readable medium of clause 19, wherein (a) comprises set the first target for a dry bulb temperature of the airflow leaving the air handler.

[0111] Clause 22. The non-transitory, machine-readable medium of clause 20, wherein (a) comprises set the first target for a temperature of ducting that receives the airflow from the air handler.

[0112] Clause 23. The non-transitory, machine-readable medium of clause 22, wherein (a) comprises set the first target above a dewpoint of air surrounding an outside of the ducting.

[0113] Clause 24. The non-transitory, machine-readable medium of clause 23, wherein (c) includes (c1) increase the flow rate of heat transfer fluid through the coil to increase the heat transfer rate through the coil and thereby decrease the temperature associated with the airflow; or (c2) decrease the flow rate of heat transfer fluid through the coil to decrease the heat transfer rate through the coil and thereby increase the temperature associated with the airflow.

[0114] Clause 25. The non-transitory, machine-readable medium of clause 19, wherein the performance metric comprises a relative humidity of the airflow upstream of the air handler.

[0115] Clause 26. The non-transitory, machine-readable medium of clause 25, wherein (a) comprises set the first target below a dewpoint temperature of the airflow upstream of the air handler.

[0116] Embodiments disclosed herein provide systems and methods for more precise control of the operation a chiller system. Specifically, in some embodiments, an air handler of the chiller system may include a heat transfer coil (or “coil”) and one or more controllers that are configured to control the heat transfer rate in the coil by precisely controlling a flow rate of the heat transfer fluid therethrough based at least in part on a total temperature change for the heat transfer fluid across the coil. The control of the heat transfer rate may in turn be controlled based on one or more other performance metrics for the airflow also circulating through the air handler. Thus, control of the heat transfer rate of the coil in the air handler may be used as a proxy for controlling the one or more other performance metric. Without being limited to this or any other theory, control of the heat transfer rate of the coil according to embodiments disclosed herein may provide a more precise and consistent method for adjusting the thermal capacity delivered to the interior space by the chiller system. As a result, this relatively precise control of the heat transfer rate through the coil may allow for enhanced thermal capacity performance from the air handler without necessitating increased infrastructure capacities(e.g., via larger piping diameters, more and / or larger pumps, etc.). Therefore, use of at least some embodiments disclosed herein may allow for enhanced operation and performance of existing chillers with minimal additional retrofit.

[0117] The preceding discussion is directed to various exemplary embodiments. However, one of ordinary skill in the art will understand that the examples disclosed herein have broad application, and that the discussion of any embodiment is meant only to be exemplary of that embodiment, and not intended to suggest that the scope of the disclosure, including the claims, is limited to that embodiment.

[0118] The drawing figures are not necessarily to scale. Certain features and components herein may be shown exaggerated in scale or in somewhat schematic form and some details of conventional elements may not be shown in interest of clarity and conciseness.

[0119] In the discussion herein and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . .” Also, the term “couple” or “couples” is intended to mean either an indirect or direct connection. Thus, if a first device couples to a second device, that connection may be through a direct connection of the two devices, or through an indirect connection that is established via other devices, components, nodes, and connections. In addition, as used herein, the terms “axial” and “axially” generally mean along or parallel to a given axis (e.g., central axis of a body or a port), while the terms “radial” and “radially” generally mean perpendicular to the given axis. For instance, an axial distance refers to a distance measured along or parallel to the axis, and a radial distance means a distance measured perpendicular to the axis. Further, when used herein (including in the claims), the words “about,”“generally,”“substantially,”“approximately,” and the like, when used in reference to a stated value mean within an approximate range of plus or minus 10% of the stated value.

[0120] While exemplary embodiments have been shown and described, modifications thereof can be made by one skilled in the art without departing from the scope or teachings herein. The embodiments described herein are exemplary only and are not limiting. Many variations and modifications of the systems, apparatus, and processes described herein are possible and are within the scope of the disclosure. Accordingly, the scope of protection is not limited to the embodiments described herein, but is only limited by the claims that follow, the scope of which shall include all equivalents of the subject matter of the claims. Unless expressly stated otherwise, the steps in a method claim may be performed in any order. The recitation of identifiers such as (a), (b), (c) or (1), (2), (3) before steps in a method claim are not intended to and do not specify a particular order to the steps, but rather are used to simplify subsequent reference to such steps.

Examples

Embodiment Construction

[0014]A climate control system, such as a chiller system, may include a refrigerant circuit and one or more separate and additional fluid circuits for exchanging heat between an interior space and an ambient environment. For instance, the interior space may be one or more interior spaces of a building or other structure, and the ambient environment may be the outdoor environment at least partially surrounding the building. Specifically, a chiller system may include a fluid circuit that is configured to transfer heat between the refrigerant circuit and the interior space(s). The fluid circuit may circulate a heat transfer fluid in a substantially singular phase (e.g., a liquid phase) between a first heat exchanger positioned along the refrigerant circuit and a second heat exchanger that is configured to exchange heat between the heat transfer fluid and an airflow that is circulated through the interior space(s). Because this second heat exchanger is configured to transfer heat betwee...

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] Not applicable.BACKGROUND

[0002] A climate control system may exchange heat between an interior space and an ambient environment via one or more fluid circuits. For instance, a climate control system may include a refrigerant circuit that is configured to transfer heat by selectively changing the phase of the refrigerant from a liquid to a vapor (and vice versa). In addition, some climate control systems, such as chillers, may include additional fluid circuits to exchange heat between the refrigerant circuit and other heat sink(s) / source(s), such the interior space(s), or the ambient environment.BRIEF SUMMARY

[0003] The present disclosure includes, without limitation, the following examples.

[0004] One embodiment is a method that controls climate control system. The method further sets a first target for a performance metric for an airflow through an air handler of a climate control system. The method additionally sets a second target for a heat transfer rate for a coil of the air handler based on the first target. In addition, the method adjusts a flow rate of heat transfer fluid through the coil to reduce an error associated with the second target.

[0005] One embodiment is a climate control system for conditioning an interior space. The climate control system includes a chiller that is configured to exchange heat with a flow of heat transfer fluid. In addition, the climate control system includes an air handler including a coil that is configured to receive the flow of heat transfer fluid therethrough. The climate control system further includes ducting coupled to the air handler that is configured to circulate an airflow between the interior space and the air handler. The climate control system additionally includes one or more controllers that are configured to set a first target for a performance metric for the airflow based on a desired climate parameter for the interior space. The one or more controllers of the climate control system further to set a second target for a heat transfer rate for the coil of the air handler based on the first target. In addition, the one or more controllers of the climate control system to adjust a flow rate of heat transfer fluid through the coil to reduce an error associated with the second target.

[0006] One embodiment is a non-transitory, machine-readable medium comprising instructions, which when executed by one or more processors. The machine-readable medium causes the one or more processors to set a first target for a performance metric for an airflow through an air handler of a climate control system. In addition, the machine-readable medium causes the one or more processors to set a second target for a heat transfer rate for a coil of the air handler based on the first target. The machine-readable medium causes the one or more processors further to adjust a flow rate of heat transfer fluid through the coil to reduce an error associated with the second target.

[0007] Embodiments described herein comprise a combination of features and characteristics intended to address various shortcomings associated with certain prior devices, systems, and methods. The foregoing has outlined rather broadly the features and technical characteristics of the disclosed embodiments in order that the detailed description that follows may be better understood. The various characteristics and features described above, as well as others, will be readily apparent to those having ordinary skill in the art upon reading the following detailed description, and by referring to the accompanying drawings. It should be appreciated that this disclosure may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes as the disclosed embodiments. It should also be realized that such equivalent constructions do not depart from the spirit and scope of the principles disclosed herein.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] For a detailed description of various embodiments, reference will now be made to the accompanying drawings in which:

[0009] FIG. 1 is a schematic diagram of a climate control system according to some embodiments disclosed herein;

[0010] FIG. 2 is a flow chart of control logic that may be employed by a controller of the climate control system of FIG. 1 according to some embodiments disclosed herein;

[0011] FIG. 3 is another schematic diagram of the climate control system of FIG. 1, in which the climate control system includes a plurality of chillers and a plurality of air handlers according to some embodiments disclosed herein;

[0012] FIG. 4 is a diagram of a method of controlling a climate control system according to some embodiments disclosed herein; and

[0013] FIG. 5 is a schematic diagram of a chiller of the climate control system of FIG. 1 according to some embodiments disclosed herein.DETAILED DESCRIPTION

[0014] A climate control system, such as a chiller system, may include a refrigerant circuit and one or more separate and additional fluid circuits for exchanging heat between an interior space and an ambient environment. For instance, the interior space may be one or more interior spaces of a building or other structure, and the ambient environment may be the outdoor environment at least partially surrounding the building. Specifically, a chiller system may include a fluid circuit that is configured to transfer heat between the refrigerant circuit and the interior space(s). The fluid circuit may circulate a heat transfer fluid in a substantially singular phase (e.g., a liquid phase) between a first heat exchanger positioned along the refrigerant circuit and a second heat exchanger that is configured to exchange heat between the heat transfer fluid and an airflow that is circulated through the interior space(s). Because this second heat exchanger is configured to transfer heat between the heat transfer fluid and an airflow, the assembly is commonly referred to as an “air handler.”

[0015] Conventional operational control over a chiller system, and particularly over an air handler of the chiller system has been lacking. Specifically, conventional approaches lack the ability to precisely control the rate of heat transfer between the heat transfer fluid and the airflow due to imperfect measurements (which may rely on averaging temperature sensors for the airflow 24 and / or averaging temperature sensors for the temperature of the coil 22), imprecise control systems, etc. As a result, the piping, pump(s), and other infrastructure for communicating the heat transfer fluid between the refrigerant circuit and air handler are often overdesigned to ensure that the air handler may be able to deliver a sufficient thermal capacity to the interior space(s) during operations. However, because chiller systems are typically useful for conditioning larger interior spaces, such as the interior spaces defined within office buildings, sports stadiums, data centers, retail spaces, manufacturing spaces, etc., even incremental capacity increases in a chiller system's infrastructure can significantly increase both the capital and operating costs.

[0016] Accordingly, embodiments disclosed herein provide systems and methods for more precise control of the operation a chiller system. Specifically, in some embodiments, an air handler of the chiller system may include a heat transfer coil (or “coil”) and one or more controllers that are configured to control the heat transfer rate in the coil by precisely controlling a flow rate of the heat transfer fluid therethrough based at least in part on a total temperature change for the heat transfer fluid across the coil. The control of the heat transfer rate may in turn be controlled based on one or more other performance metrics for the airflow also circulating through the air handler. Thus, control of the heat transfer rate of the coil in the air handler may be used as a proxy for controlling one or more other performance metric. Without being limited to this or any other theory, control of the heat transfer rate of the coil according to embodiments disclosed herein may provide a more precise and consistent method for adjusting the thermal capacity delivered to the interior space by the chiller system. As a result, this relatively precise control of the heat transfer rate through the coil may allow for enhanced thermal capacity performance from the air handler without necessitating increased infrastructure capacities (e.g., via larger piping diameters, more and / or larger pumps, etc.). Therefore, use of at least some embodiments disclosed herein may allow for enhanced operation and performance of existing chillers with minimal additional retrofit.

[0017] Referring now to FIG. 1, a climate control system 10 is shown according to some embodiments disclosed herein. The climate control system 10 includes a chiller 12, and thus, climate control system 10 may be referred to herein as a “chiller system”10. The chiller 12 may include or define a refrigerant circuit 14 that is configured to circulate a refrigerant between a pair of heat exchangers to transfer heat during operations. In some embodiments, the chiller 12 and refrigerant circuit 14 may be configured in the manner shown in FIG. 5 and described in more detail hereinafter.

[0018] The chiller system 10 may also include an air handler 20 and a heat transfer fluid circuit 15 (or “fluid circuit 15”) that is coupled to and between the air handler 20 and the chiller 12. The fluid circuit 15 may include a first line 17 that is configured to carry heat transfer fluid from the chiller 12 to the air handler 20, and a second line 16 that is configured to carry the heat transfer fluid from the air handler 20 back to the chiller 12. The lines 16, 17 may comprise pipes, hoses, conduit, channel, or any other suitable fluid conveyance member or system.

[0019] In some embodiments, the heat transfer fluid flowing in fluid circuit 15 may comprise water, such as substantially pure water, reverse osmosis water, or deionized water or an aqueous solution that includes water and one or more other constituents or additives. For instance, in some embodiments, the heat transfer fluid may comprise a water-glycol solution. Still other aqueous solutions are contemplated for the heat transfer fluid in fluid circuit 15 in various embodiments.

[0020] The air handler 20 may be a heat exchanger that is configured to transfer heat between the heat transfer fluid flowing in the fluid circuit 15 and an airflow 24. The air handler 20 may include a heat transfer coil 22 (or “coil”22) that is positioned along and therefore a part of the heat transfer fluid circuit 15. Specifically, the coil 22 may be coupled to both the first line 17 and second line 16 so that heat transfer fluid that is flowing to the air handler 20 along the first line 17 is flowed through the coil 22 and then is discharged into the second line 16 so it may return to the chiller 12 as previously described. The coil 22 may comprise a plurality of parallel fluid coils that are exposed to the airflow 24. The coil 22 has been represented in a relatively simple and schematic manner in FIG. 1 so as to simplify the drawings.

[0021] One or more pumps or other fluid conveyance devices may be included along the heat transfer fluid circuit 15, such as along one or both of the lines 17, 16. However, these additional features are not shown in FIG. 1 in order to simplify the drawings.

[0022] During operations, as the heat transfer fluid in the fluid circuit 15 is circulated through the coil 22, the airflow 24 is flowed over and around the outside of the coil 22 so that heat is transferred between the heat transfer fluid and the airflow 24 via the coil 22. The airflow 24 may then be emitted from the air handler 20 and flowed through an interior space 32 via ducting 30 so as to condition (e.g., heat, cool, dehumidify, etc.) the interior space 32. In some embodiments, the heat transfer fluid flowing in fluid circuit 15 may be maintained in a substantially liquid state as it circulates through and between the chiller 12 and air handler 20.

[0023] The ducting 30 may also return the airflow 24 back to the air handler 20 from the interior space 32. Specifically, the airflow 24 may flow from the interior space 32, through the ducting 30 to an inlet 26 of the air handler 20. Within the air handler 20, the airflow 24 may flow over and around the coil 22 to exchange heat with the heat transfer fluid of the fluid circuit 15 as previously described. Thereafter, the now conditioned airflow 24 may flow out of an outlet 28 of the air handler 20 and back into the interior space 32 via the ducting 30. Additional air 31 may be flowed into the air handler 20 from an outdoor or other ambient environment 33. This additional air 31 may be merged with the airflow 24 via the ducting 30, upstream or downstream of the inlet 26 of air handler 20.

[0024] One or more blowers or other air movers may be coupled to or along the ducting 30 in order to facilitate the flow of airflow 24 between the air handler 20 and interior space 32 during operations. In addition, the ducting may include additional dampers, valves, or other flow control devices that are configured to distribute the airflow 24 to multiple different outlets that flow into a single interior space 32 or multiple interior spaces 32. However, these additional features are not shown in FIG. 1 in order to simplify the drawings.

[0025] In some embodiments, the chiller system 10 may be configured to heat or cool the interior space 32 via the refrigerant circuit 14, the fluid circuit 15, and the airflow 24. Specifically, when the chiller system 10 is operating to cool the interior space 32 (so that the chiller system 10 is operating in a so-called “cooling mode”), the refrigerant circuit 14 may receive heat from the heat transfer fluid circulating in the fluid circuit 15. As a result, the heat transfer fluid discharged from the chiller 12 into the first line 17, may be cold or cool in temperature. The heat transfer fluid may then flow through the coil 22 so as to receive heat from the airflow 24 flowing through the air handler 20. This exchange of heat between the airflow 24 and heat transfer fluid via the coil 22 may cool the airflow 24 and heat the heat transfer fluid. In some embodiments, the temperature of the coil 22 may be less than a dewpoint temperature of the airflow 24 during the cooling mode operation, so that water may condense onto the coil 22. Thus, in some embodiments, the air handler 20 may include one or more pans or other collectors 27 that are configured to collect this condensation 29 and channel it to a drain or other collection point.

[0026] In some embodiments, the chiller system 10 may be configured to heat the interior space via the refrigerant circuit 14, the fluid circuit 15, and the airflow 24. Specifically, when the chiller system 10 is operating the heat the interior space (so that the chiller system 10 is operating in a so-called “heating mode”), the flow direction of the refrigerant circuit 14 may be reversed so that heat is transferred from the refrigerant to the heat transfer fluid flowing in the fluid circuit 15. Thus, in these embodiments, the heat transfer fluid flowing along the first line 17 to the air handler 20 may be hot or warm so that the airflow 24 is heated when it contacts the coil 22.

[0027] The chiller system 10 may also include a controller 50 that is configured to control one or more operational aspects thereof. For instance, as is described in more detail herein, the controller 50 may be configured to monitor and control the rate of heat transfer through the coil 22 of air handler 20 so as to ultimately affect one or more performance metrics of the airflow 24 during operations.

[0028] The controller 50 may be (or may be incorporated within) a main or master controller for the chiller system 10. Alternatively, the controller 50 may be a standalone controller 50 for controlling one or more aspects of the air handler 20. Regardless, the controller 50 may be described and referred to herein as being a part of the chiller system 10 according to at least some embodiments.

[0029] The controller 50 may comprise one or more computing devices, such as a computer, tablet, smartphone, server, circuit board, or other computing device(s) or system(s). Thus, controller 50 may include a processor 52 and a memory 54.

[0030] The processor 52 may include any suitable processing device or a collection of processing devices. In some embodiments, the processor 52 may include a microcontroller, central processing unit (CPU), graphics processing unit (GPU), timing controller (TCON), scaler unit, or some combination thereof. During operations, the processor 52 executes machine-readable instructions (such as machine-readable instructions 56) stored on memory 54, thereby causing the processor 52 to perform some or all of the actions attributed herein to the controller 50. In general, processor 52 fetches, decodes, and executes instructions (e.g., machine-readable instructions 56). In addition, processor 52 may also perform other actions, such as, making determinations, detecting conditions or values, etc., and communicating signals. If processor 52 assists another component in performing a function, then processor 52 may be said to cause the component to perform the function.

[0031] The memory 54 may be any suitable device or collection of devices for storing digital information including data and machine-readable instructions (such as machine-readable instructions 56). For instance, the memory 54 may comprise volatile storage (such as random-access memory (RAM)), non-volatile storage (e.g., flash storage, read-only memory (ROM), etc.), or combinations of both volatile and non-volatile storage. Data read or written by the processor 52 when executing machine-readable instructions 56 can also be stored on memory 54. Memory 54 may comprise or include a “non-transitory machine-readable medium,” where the term “non-transitory” does not include or encompass transitory propagating signals.

[0032] The processor 52 may include one processing device or a plurality of processing devices that are distributed within (or communicatively coupled to) controller 50 or more broadly within the chiller system 10. Likewise, the memory 54 may include one memory device or a plurality of memory devices that are distributed within (or communicatively coupled to) controller 50 or more broadly within the chiller system 10. Thus, the controller 50 may comprise a single controller or a plurality of individual “controllers” distributed throughout the chiller system 10 and that may be communicatively coupled to one another. Thus, the controller 50 may comprise “one or more” controllers, or “a plurality of” controllers. In some embodiments, the controller 50 may also comprise one or more “controllers” (including a processor and a memory as previously described) that are remotely positioned from the chiller system 10.

[0033] The controller 50 may be communicatively coupled to one or more sensors 36, 38, 40, 42, 44 that are configured to detect one or more operating parameters of the chiller system 10 of fluid flows associated therewith. As referred to herein, when a sensor (such as the sensors 36, 38, 40, 42, 44 or other sensors described herein) is said to detect a value, such “detection” would include any method by which the sensor may measure, estimate, compute, detect, etc. the value itself or some other value that is indicative thereof. Thus, no particular limitation is intended for the particular method by which a sensor “detects” a value (or value indicative thereof) unless otherwise stated.

[0034] The sensors 36, 38 may be configured to detect the temperature of the heat transfer fluid flowing in the lines 17, 16, respectively. Thus, the sensors 36, 38 may be referred to herein as “temperature sensors.” The temperature sensors 36, 38 may each comprise any suitable temperature sensing device, system, or arrays. For instance, the temperature sensors 36, 38 may comprise thermocouples, semiconductor-based temperature sensors, resistance temperature detectors (RTDs), thermistors, among others. Other temperature sensors described herein may also comprise any of these suitable temperature sensing devices, systems, or arrays.

[0035] The precise positioning and arrangement of the temperature sensors 36, 38 may be varied in different embodiments. For instance, in some embodiments, one or both of the temperature sensors 36 and 38 may not be positioned along the lines 17, 16, respectively, and may be positioned or integrated with the chiller 12 or the air handler 20 (such as on a port, body, or flow conduit on or defined by the chiller 12 or air handler 20). Thus, the indicated position of the temperature sensors 36, 38 along the lines 17, 16, respectively, is illustrative of only some embodiments. In some embodiments, the controller 50 may determine the temperature of the heat transfer fluid flowing to the air handler 20 via line 17 based on an output of a controller, sensor, or other device of the chiller 12. Thus, in one or more embodiments, the temperature sensors 36 and 38 may be omitted.

[0036] During operation, the controller 50 may receive outputs from the temperature sensors 36, 38 and a flow rate determined from the flow control device 34 to determine a heat transfer rate for the coil 22. Specifically, the controller 50 may determine the change in temperature of the heat transfer fluid across the coil 22 based on (or as) a difference between the temperatures of the heat transfer fluid in the lines 17, 16 as detected by the temperature sensors 36, 38, respectively. The change in temperature in the heat transfer fluid across the coil 22 may be characteristic or indicative of the heat transfer rate of the coil 22 during operations.

[0037] The controller 50 may also be communicatively coupled to a flow control device 34 positioned along or coupled to the first line 17, upstream or downstream of the coil 22. The controller 50 may adjust the flow control device 34 so as to precisely control the flow rate of heat transfer fluid through the coil 22 so as to control the heat transfer rate of the coil 22 during operations. In some embodiments, the heat transfer rate can vary based on the supply temperature 38. In these embodiments, the supply temperature 38 is controlled by the chiller 12.

[0038] In some embodiments, the flow control device 34 may comprise any suitable valve or valve system for controlling the flow rate of heat transfer fluid through the coil 22. For instance, the control valve 34 may comprise a pressure-independent flow control device (e.g., a pressure-independent metering control valve), such as those described in U.S. Pat. No. 10,036,568, the contents of which being incorporated by reference. Specifically, the control valve 34 may include a valve (or orifice), and a pilot-operated pressure regulator. The pilot-operated pressure regulator is configured to maintain a fixed pressure differential across the control valve. Thus, regardless of the pressure of the heat transfer fluid flowing along the line 17, the flow control device 34 may be configured to achieve and maintain a particular flow rate of heat transfer fluid therethrough, constituting a metering control valve.

[0039] It should be appreciated that the flow control device 34 may include additional or alternative flow control devices, other than a control valve as previously described. For instance, in some embodiments, the flow control device 34 may comprise a pump, such as a variable speed pump that is configured to selectively alter the pressure and flow rate of the heat transfer fluid discharged therefrom. Thus, configuring the flow control device 34 as a control valve as previously described is only illustrative of some embodiments.

[0040] During operations, the controller 50 may adjust a position or operational state of the flow control device 34 so as to achieve or maintain a desired heat transfer rate in the coil 22 as indicated by outputs from the temperature sensors 36, 38. In some embodiments, the controller 50 may adjust the heat transfer rate of the coil 22 via adjustments to the flow control device 34 based on one or more other measurements or flow parameters associated with the air handler 20. For instance, the controller 50 may control the heat transfer rate of the coil 22 based on one or more parameters associated with the airflow 24 flowing through, to, or from the air handler 20.

[0041] In some embodiments, the chiller system 10 may include additional sensors 40, 42 that are coupled to one or more of the air handler 20 and the ducting 30. In some embodiments, the sensor 40 may be coupled to the outlet 24 of air handler 20, and the sensor 42 may be coupled to the inlet 24 of air handler 20. The sensor 42 may be configured to detect one or more parameters of the airflow 24, upstream of the coil 22, and the sensor 40 may be configured to detect one or more parameters of the airflow 24, downstream of the coil 22. For example, in some embodiments, the sensor 40 may detect a temperature, a relative humidity, or both of the airflow 24 downstream of the coil 22, and the sensor 42 may detect a temperature, a relative humidity of both of the airflow 24 upstream of the coil 22. In some embodiments, the controller 50 may be communicatively coupled to an additional sensor 44 that is configured to detect one or more parameters of the ambient environmental airflow 33. Thus, while the sensors 40, 42, 44 are represented as singular sensors in FIG. 1, it should be appreciated that one or more of the sensors 40, 42, 44 may be multiple sensors (such as a sensor array) that is configured to detect multiple parameters or values.

[0042] During operations, the controller 50 may control the heat transfer rate of the coil 22, via adjustment to the flow rate of heat transfer fluid through coil 22 via flow control device 34 based on one or more other parameters of or relating to the airflow 24, such as determined via outputs from one or more of the additional sensors 40, 42, 44. More specifically, the controller 50 may set or receive a first target value for a parameter of or relating to the airflow 24, and then may set a second target value for the heat transfer rate through the coil 22 (or value indicative thereof such as flow rate through coil 22) based on the first target value. Thus, the controller 50 may apply a cascaded control scheme whereby the heat transfer rate through the coil 22 is controlled as a proxy to achieve a desired value (e.g., the first target value) of the one or more other parameters of or relating to the airflow 24.

[0043] Without being limited to this or any other theory, the flow control device 34 and temperature sensors 36, 38 provide a precise system for controlling the heat transfer rate through the coil 22 during operations. Specifically, the flow control device 34 is effective for controlling a total flow rate of the heat transfer fluid within relatively tight limits, and the temperature sensors 36, 38 are configured to more effectively measure a representative temperature differential of the heat transfer fluid as it travels through a more confined space (e.g., the lines 17, 16). As a result, by basing control of the one or more other parameters of the airflow 24 on the rate of heat transfer through the coil 22, a finer level of control is achievable so that additional capacities can be reliably achieved from the chiller system 10 and its existing infrastructure as previously described.

[0044] Referring now to FIG. 2, a flow chart of the control logic employed by the controller 50 for controlling the heat transfer rate of the air handler 20 of chiller system 10 is shown according to some embodiments. In the following description of the flow chart of FIG. 2, continuing reference will be made to the chiller system 10 of FIG. 1. However, it should be appreciated that embodiments of the control logic illustrated in the flow chart of FIG. 2 may be utilized to control the heat transfer rate of an air handler of another climate control system that is different from the chiller system 10 shown in FIG. 1 in at least some respects. In some embodiments, the chiller system 10 can be a district cooling system or another type of an interposing heat exchanger (e.g., a heat exchanger used to isolate a floor of a building), or another type of chiller. The control logic shown in FIG. 2 may be representative of at least some of the machine-readable instructions 56 stored on memory 54 and executed by processor 52 of controller 50 in FIG. 1 (or of another controller as noted herein).

[0045] Initially, a user 60 may select a value for a desired climate parameter at block 62. The user 60 may be, for example, an occupant of the interior space 32 (FIG. 1), a technician, or other personnel for the building defining the interior space 32. The user 60 may input the desired climate parameter of block 62 directly to the controller 50 or to another controller or other suitable user input device, such as a thermostat or software application running on another computing device such as a computer, tablet, or smartphone, etc. In some embodiments, the value for the desired climate parameter of block 62 may be determined by the controller 50 or another controller based on some other input, stimulus, measurement, operating mode of chiller system 10, etc.

[0046] In some embodiments, the desired climate parameter in block 62 may be any suitable climate parameter that describes the state or condition of the climate within the interior space 32 (FIG. 1). For instance, in some embodiments, the desired climate parameter in block 62 may comprise a desired temperature, a desired relative humidity, or some combination thereof.

[0047] The controller 50 (or another controller of or communicatively coupled to chiller system 10) may set a target airflow performance metric (a “first target”) for the airflow 24 at block 64. The target airflow performance metric at block 64 may be selected to correspond with the desired climate parameter of block 62 so that achieving the target airflow performance metric set at block 64 will provide the desired climate parameter of block 62 to the interior space 32. For instance, when the climate parameter of block 62 is a desired or set point temperature for the interior space 32, the target airflow performance metric set at block 64 may comprise a target temperature, such as a target dry bulb temperature, for the airflow 24 discharged from the air handler 20 that is configured to achieve the set point temperature in the interior space 32. Conversely, when the desired climate parameter of block 62 is a desired relative humidity for the interior space 32, the target airflow performance metric set at block 64 may comprise a target relative humidity or a target dewpoint temperature for airflow 24 discharged from the air handler 20 that is configured to achieve the desired relative humidity for the interior space 32.

[0048] After the target airflow performance metric is set at block 64, the controller 50 may then set a target heat transfer rate through the coil 22 of the air handler 20 at block 66. In some embodiments, the target heat transfer rate in block 66 is at least partially based on the target airflow performance metric from block 64. As previously described, the heat transfer rate of the coil 22 may be more precisely monitored and controlled via flow control device 34 and sensors 36, 38 than other parameters associated with the airflow 24. In addition, the air flow performance metric (such as temperature, relative humidity, or both) for the airflow 24 may be at least partially based on the rate of heat transfer between the heat transfer fluid and airflow 24 via coil 22. As a result, the target airflow performance metric from block 64 is essentially converted to a target heat transfer rate of the coil 22 via block 66 that is more precisely monitored and adjusted by the controller 50 during operations.

[0049] Once the target heat transfer rate of the coil 22 is set at block 66, the controller 50 may be adjust the flow rate of the heat transfer fluid through the coil 22 via the flow control device 34 at block 68 to achieve (or maintain) the target heat transfer rate based on feedback received from the temperature sensors 36, 38 and 34 (fluid flow rate). Specifically, in some embodiments, the controller 50 may determine an error between the current heat transfer rate of the coil 22 and the target heat transfer rate set at block 66 via outputs from the temperature sensors 36, 38 and from liquid flow rate 34. Then, the controller 50 may adjust a flow rate of the heat transfer fluid through the coil 22 via the flow control device 34 in order to reduce or eliminate the error. In some embodiments, the controller 50 may apply a proportional, integral, derivative (PID) control scheme for reducing the error of the heat transfer rate of the coil 22 via adjustments to the flow control device 34 or may apply some other control logic (such as anyone or more of the proportional, integral, derivative controls).

[0050] In some embodiments, the control logic of FIG. 2 may include a feedback from block 68 to block 64 in order to update the targets for the airflow performance metric and heat transfer rate of the coil 22 as appropriate. For instance, as the error in the airflow performance metric is reduced, the targets for one or both of the airflow performance metric and the heat transfer rate of coil 22 may be updated to slow a rate of change of the heat transfer rate of coil 22 and airflow performance metric in order to avoid overshoot, or inefficient operation of the chiller system 10.

[0051] In some embodiments, another controller (that is different from the controller 50) may carry out block 64, and then may communicate the target airflow performance metric to the controller 50, which may then carry out blocks 66 and 68 as previously described. In some embodiments, the other controller may carry out both blocks 64 and 66, and then may communicate either target heat transfer rate of the coil 22 to the controller 50 which then carries out block 68 to reduce the error as previously described. Still other combinations of controllers (such as controller 50 alone or in combination with other controllers) for carrying out the control logic of FIG. 2 are contemplated for various embodiments.

[0052] In some embodiments, the controller 50 (or another controller as previously described) may set the target heat transfer rate for the coil 22 based on an error in the target airflow performance metric at block 64. Specifically, if the current airflow performance metric is far from the target set at block 64 (so that the error in the airflow performance metric is large), the target heat transfer rate of the coil 22 may be set more aggressively in order to more quickly reduce the error of the airflow performance metric. Thus, in some embodiments, the target heat transfer rate for the coil 22 may be set at block 66 based at least in part on the current error in the airflow performance metric relative to the target set at block 64.

[0053] In some embodiments, the precise control of the heat transfer rate of the coil 22 via the controller 50 may unlock additional heat transfer from the heat transfer fluid of fluid circuit 15 that would not otherwise be reliably achieved via conventional control methods. For instance, by precisely controlling the heat transfer rate of the coil 22, a greater temperature change in the heat transfer fluid can be reliably achieved and maintained during operation by use of the existing infrastructure of the chiller system 10. In some instances, a conventional chiller control may aim to reliably achieve about a 30 or more ° F. temperature rise for the heat transfer fluid across the coil 22 during a cooling mode operation of the chiller system. Moreover, the chiller system may be generally overdesigned (e.g., such as via larger piping sizes for the fluid circuit 15, standard pressure dependent control valves, imprecise valve operator / positioners, larger pumps, etc.) so as to overflow the heat transfer fluid through the coil 22 in order to reliable achieve this modest temperature rise in light of the less precise conventional methods of control based solely on parameters related to the airflow 24. However, when the more precise control described herein that is based on the heat transfer rate of the coil 22 as determined via the sensors 36, 38 and flow control device 34, the flow rate of the fluid circuit 15 of existing chillers may be optimized / minimized to reliable achieve much greater temperature rises in the heat transfer fluid of fluid circuit 15. For example, in some embodiments, by use of the more precise control methods described herein, the heat transfer fluid flowing in fluid circuit 15 may reliably achieve temperature rises of about 30° F. or more during a cooling mode operation of the chiller system 10. This additional thermal heat transfer in the air handler 20 can, in turn, lead to more efficient operation of the chiller system 10 overall and may help to avoid costly upgrades (including the addition of more chillers 12).

[0054] Some specific examples of the control logic of FIG. 2 are now described for the chiller system 10 of FIG. 1 in order to further illustrate some specific embodiments. These specific examples illustrate the operation of control logic of FIG. 2 with respect to the specific climate parameters for the interior space 32 and specific target airflow performance metrics (block 64). However, these specific examples are merely illustrative of some embodiments and are not meant to limit other potential implementations of the control logic in FIG. 2. In describing these specific examples, continuing reference will be made to the chiller system 10 of FIG. 1 and the example control logic of FIG. 2.

[0055] For example, in some embodiments the desired climate parameter in block 62 of FIG. 2 may comprise a desired temperature of the interior space 32 (FIG. 1). As a result, the target airflow performance metric set at block64 may comprise a temperature of the airflow 24 that is discharged from the air handler 20 to the interior space 32 via ducting 30. In some embodiments, the target airflow temperature may be equal to or more likely less than the desired climate parameter in block 62 of FIG. 2. Specifically, as would be appreciated by one having ordinary skill in the art, a target airflow temperature for reducing a temperature of an interior space (such as interior space 32) may be generally lower than the desired or set point temperature for the interior space so that the desired temperature may be achieved after a reasonable period of operating time.

[0056] In some embodiments, the temperature of the airflow 24 in the outlet 28 or in the ducting 30, downstream of the air handler 20 may be detected via the temperature sensor 40. In some embodiments, the temperature sensor 40 may comprise a probe that extends into the outlet 28 or the ducting 30 downstream of air handler 20 in order to sample and measure the temperature of the airflow 24. In some embodiments, the sensor 40 may measure the dry bulb temperature of the airflow 24.

[0057] Once the target airflow temperature is set or received as the target airflow performance metric at block 64 (FIG. 2), the controller 50 (or another controller as previously described) may then set the target heat transfer rate for the coil 22 (e.g., block 66 in FIG. 2) based on the target temperature of the airflow 24 discharged from the air handler 20 or the error in the temperature of the airflow 24 relative to the target via outputs form the temperature sensor 40 as previously described. In addition, the controller 50 may adjust the flow rate of heat transfer fluid through the coil 22 via adjustments to the flow control device 34 to reduce an error in the heat transfer rate in the coil 22 relative to the target value as informed by the temperature sensors 36, 38 and flow control valve flow rate as previously described. As is also previously described, the controller 50 may adjust the target heat transfer rate of the coil 22 as an error associated with the temperature of the airflow 24 discharged from the air handler 20 is reduced relative to its target (e.g., the target airflow performance metric of block 64 in FIG. 2). Thus, in this example, the controller 50 may achieve and maintain the target discharge temperature of the airflow 24 via the more precise control of the heat transfer rate through the coil 22.

[0058] In some embodiments, one or more target values applied by the controller 50, such as the target dry bulb temperature of the airflow 24 discharged from the air handler as previously described, may be modified or updated based on additional temperatures (or other values) associated with the chiller system 10. For instance, in some embodiments, the temperature of an outer surface of the ducting 30 downstream of the air handler 20 may be detected by the sensor 40 (or another sensor) during operations and compared to a dewpoint temperature for an environment surrounding the ducting 30. If the temperature of the outer surface of the ducting 30 is equal to or less than the dewpoint temperature of this surrounding environment, moisture may condense out of the surrounding environment onto the outer surface of the ducting 30, which thereby may lead to mold, mildew, or other undesirable organic growth. As a result, during operations, the controller 50 may update one or both of the target values associated with the dry bulb temperature for the airflow 24 discharged from air handler 20 and the heat transfer rate of the coil 22 in order to avoid condensing moisture on an outer surface of the ducting 30. Specifically, the controller 50 may increase the target value for the dry bulb temperature of the airflow 24 downstream of the coil 22 and / or may decrease the target heat transfer rate of the coil 22 in order the maintain the temperature of the outer surface of the ducting 30 above the dewpoint temperature of the surrounding environment. In some embodiments, with the controller 50 updating the dry bulb temperatures of the airflow 24 using data from sensor 40,the target of the temperature of the airflow 24 downstream of the coil 22 in a sensible cooling regime may allow a fan or blower that is generating the airflow 24 to be operated at a relatively lower speed and this may increase the overall operating efficiency for the chiller system 10.

[0059] In some embodiments, the desired climate parameter in block 62 of FIG. 2 may comprise a desired relative humidity (or an indicative or related value) of the interior space 32 (FIG. 1). As a result, the target airflow performance metric set at block 64 (by controller 50 or another controller as previously described) may comprise a relative humidity (or other related value such as a dewpoint temperature) of the airflow 24 that is discharged from the air handler 20 to the interior space 32 or the return air from ducting 30.

[0060] In some embodiments, the target airflow performance metric set at block 64 of FIG. 2 for reducing a relative humidity of the interior space 32 may comprise target operating temperature for the coil 22 that is at or below a dewpoint temperature of the airflow 24 downstream of the coil 22 of air handler 20. Without being limited to this or any other theory, the dewpoint temperature of a volume of air (such as airflow 24) is the temperature at which moisture begins to condense out of that volume of air. Thus, for the chiller system 10, if the temperature of the coil 22 were lowered to or below the dewpoint temperature of the airflow 24, moisture will begin to condense out of the airflow 24 onto the coil 22 as the airflow 24 passes through the air handler 20. While a reduction of the temperature of coil 22 below the dewpoint temperature of the incoming airflow 24 will result in a more rapid condensation of moisture (and therefore a more rapid reduction of the relative humidity of the airflow 24 delivered to interior space 32), every degree of incremental reduction in temperature of the coil 22 comes at the cost of additional thermal capacity delivered from the chiller 12, which reduces the operating efficiency of the chiller system 10.

[0061] Accordingly, it would be most efficient to precisely maintain the operating temperature of the coil 22 at or just below the dewpoint temperature setpoint in order to reduce a moisture content of the airflow 24, while avoiding the operating inefficiencies associated with overcooling the coil 22. Conventional control schemes for an air handler lack the precision that would allow for such precise control of the coil 22 at the dewpoint temperature during operations. However, because the operating temperature of the coil 22 is a function of the heat transfer rate through the coil 22, the controller 50 may apply the precise control scheme of heat transfer rate via the flow control device 34 and temperature sensors 36, 38 as previously described, in order to achieve or maintain the operating temperature of the coil 22 at or just below the dewpoint temperature to provide dehumidification for the airflow 24 while maintaining maximum operation efficiency for chiller system 10.

[0062] During operations, the controller 50 (or another controller as previously described) may receive outputs from one or more sensors, such as sensor 42, in order to determine the dewpoint temperature of the airflow 24, upstream of the coil 22. For instance, in some embodiments, the sensor 42 may comprise a suitable sensor or array of sensors for detecting the dewpoint temperature of the airflow 24 (or one or more values indicative thereof). For instance, the sensor 42 may comprise a temperature sensor that is configured to measure a dry bulb temperature of the airflow 24 upstream of the coil 22, and a humidity sensor that is configured to measure a relative humidity of the airflow 24 upstream of the coil 22. The temperature and the relative humidity of the airflow 24 may, in turn be used to compute the dewpoint temperature. In some embodiments, the sensor 42 may determine one of the temperatures of relative humidity of the airflow, while additional sensors, such as sensors positioned in the interior space 32, may determine the other of the temperature or relative humidity of the airflow 24. In some embodiments, the controller 50 may determine the dewpoint temperature of the airflow 24 based on both temperature and relative humidity measurements taken by use of sensors positioned in the interior space 32. In some embodiments, the sensor 42 (or another sensor) may comprise a hygrometer or other suitable sensor for more directly determining the dewpoint temperature of the airflow 24.

[0063] Once the dewpoint temperature of the airflow upstream of the coil 22 is determined, the dewpoint temperature may be used to select an appropriate target dewpoint temperature for the coil 22 as the target airflow performance metric in block 64 of FIG. 2. The dewpoint temperature of the coil 22 may comprise an average dewpoint temperature of the coil 22 that may be computed based on the dewpoint temperature change across the coil 22 via outputs from the temperature sensors 36, 38. In some embodiments, the target dewpoint temperature of the coil 22 may be equal to or at least based on the dewpoint temperature of the airflow 24 upstream of the coil 22. For instance, in some embodiments, the target dewpoint temperature of the coil 22 may be less than the dewpoint temperature by a pre-determined offset, such as 1° F., 2° F., 5° F., etc. to ensure that a majority of the coil 22 surface may be below the dewpoint temperature during operations.

[0064] In some embodiments, the controller 50 may set or receive a target dewpoint temperature for the airflow discharged from the air handler 20 and may control the heat transfer rate through the coil 22 based at least in part on the target dewpoint temperature. Specifically, the controller 50 may set or receive a target dewpoint for the airflow 24 downstream of the coil 22 based on a desired relative humidity for the interior space (e.g., as a desired climate parameter in box 62 of FIG. 2). A sensor (such the sensor 40) may detect one or more variables, such as temperature and relative humidity, of the airflow 24 downstream of the coil 22 that may be used by the controller 50 to determine an error between the current dewpoint of airflow 24 downstream of the coil 22 and the target dewpoint. This error may then be used to determine a target heat transfer rate of the coil 22 that may then drive the dewpoint temperature of the airflow 24 toward the target dewpoint temperature.

[0065] In some embodiments, the controller 50 may set a target value for the heat transfer rate of the coil 22 based on a plurality of climate parameters (and associated airflow performance metrics) associated with the interior space 32. For instance, in some embodiments, a user may input both a desired temperature and / or a desired relative humidity as desired climate parameters for the interior space 32 (block 62 in FIG. 2). In response, the controller 50 may monitor the values of the temperature and relative humidity of the airflow 24 upstream of the coil 22 (or within the interior space 32 as previously described). When the relative humidity (or dewpoint temperature as previously described) is below a threshold or target value (which may correspond to a target airflow performance metric in block 64 of FIG. 2), the controller 50 may select the target heat transfer rate through the coil 22 to provide a target dry bulb temperature of the airflow 24 downstream of coil 22 as previously described. Thus, the controller 50 may control the heat transfer rate of the coil 22 in order to achieve and maintain multiple desired climate parameters for the interior space (block 62 in FIG. 2) during operations.

[0066] In some embodiments, when the relative humidity of the airflow 24 downstream of the coil 22 is below a threshold and the controller 50 is controlling the heat transfer rate of the coil 22 to achieve a desired dry bulb temperature of the airflow 24 downstream of the coil 22 as previously described, the controller 50 may further control the heat transfer rate of the coil 22 to achieve a relatively low target temperature for the airflow 24 downstream of coil 22. Specifically, when relative humidity of the airflow 24 is within a desired or acceptable range, the air handler 20 is primarily operating to perform sensible cooling (or primarily sensible cooling) of the airflow 24. As a result, reducing a target of the temperature of the airflow 24 downstream of the coil 22 in a sensible cooling regime may allow a fan or blower that is generating the airflow 24 to be operated at a relatively lower speed, which may increase the overall operating efficiency for the chiller system 10.

[0067] Referring now to FIG. 3, in some embodiments, the chiller system 10 may include a plurality of chillers 12 that circulate heat transfer fluid through a plurality of air handlers 20 for cooling a plurality of interior spaces 32 within a larger building or complex 70. In some of these embodiments, the chillers 12 may circulate the heat transfer fluid to a particular air handler 20, a subset of the air handlers 20, or all of the air handlers 20. For instance, in some embodiments, all or a subset of the chillers 12 may discharge heat transfer fluid to a line or manifold that the distributes the heat transfer fluid through one, a subset, or all of the air handlers 20 during operations.

[0068] The chiller system 10 may include one or more controllers 50 (collectively shown as a controller 50 in FIG. 3that are configured to adjust a position of one or more flow control devices 34 that are upstream of each of (or a subset of) the air handlers 20, so as to control a flow rate of the heat transfer fluid through the coils 22 of the air handlers 20 as previously described. Thus, during operations, the controller(s) 50 may set a target heat transfer rate through the coils 22 of the corresponding air handlers 20 based on target values for one or more airflow performance metrics associated with the airflow (such as a temperature, relative humidity, dewpoint temperature, etc.), that is in turn based on a desired climate parameter for the corresponding indoor space 32 as previously described. In some embodiments, each air handler 20 may include a separate controller 50 that is configured to control the corresponding flow control device 34 as previously described. Alternatively, in some embodiments a plurality of the air handlers 20 (including a subset of the air handlers 20 or all of the air handlers 20) may have a single controller 50 that controls the flow rate though each of the plurality of air handlers 20 as previously described.

[0069] Referring now to FIG. 4, a method for controlling a climate control system is shown according to some embodiments. The method 100 may be performed by use of embodiments of the chiller system 10, but it should be appreciated that the method 100 may be performed by use of other climate control systems that are different from one or more embodiments of the chiller system 10 in at least some respects. Thus, in describing the method 100, continuing reference will be made to the chiller system 10 shown in FIG. 1 and the control logic of FIG. 2.

[0070] In addition, the method 100 may be at least partially performed by a processor of a controller, such as the processor 52 of controller 50 in FIG. 1. Thus, the method 100 may be at least partially illustrative of embodiments of the machine-readable instructions 56 stored on the memory 54.

[0071] Initially, the method 100 includes setting a first target for a performance metric for an airflow through an air handler of a climate control system at block 102. For instance, as previously described for the control logic of FIG. 2, a first target for a performance metric of or relating to the airflow 24 through the air handler 20 may be set based on a desired climate parameter for the interior space 32. In some embodiments, the desired climate parameter for the interior space 32 may be a desired temperature or relative humidity, and the corresponding first target for the performance metric in block 102 may comprise a suitable target for achieving the desired climate parameter, such as a target dry bulb temperature, relative humidity, dewpoint temperature, etc. of the airflow 24, such as the airflow leaving the air handler 20.

[0072] In addition, the method 100 includes setting a second target for a heat transfer rate for a coil of the air handler based on the first target at block 104 and adjusting a flow rate of heat transfer fluid through the coil to reduce an error associated with the second target at block 106. For instance, as previously described for the chiller system 10, the controller 50 may set a target for the heat transfer rate through coil 22 that is configured to achieve the target for the air performance metric. Thus, as previously described, because the controller 50 may control the heat transfer rate through the coil 22 more precisely than other parameters associated with the air handler 20, the controller 50 may control the heat transfer rate of the coil 22 as a proxy for achieving the target airflow performance metric.

[0073] Referring now to FIG. 1, a schematic representation of an embodiment of a chiller 12 of the chiller system 10 of FIG. 1 is shown according to some embodiments disclosed herein. As previously described, the chiller 12 includes a refrigeration circuit 14 that is configured to circulate a refrigerant to exchange heat between the interior space(s) 32 of the building and the ambient environment 33 (e.g., such as the outdoor environment that surrounds the building defining the interior space(s) 32). The refrigeration circuit 14 may include a first heat exchanger 222 and a second heat exchanger 224. The first heat exchanger 222 is configured to exchange heat between the refrigerant and a working fluid 244 of an ambient heat exchange assembly 242, and the second heat exchanger 224 is configured to exchange heat between the refrigerant and the heat transfer fluid flowing in heat transfer fluid circuit 15 as previously described.

[0074] As previously described, the heat transfer fluid may circulate along the heat transfer fluid circuit 15 between the second heat exchanger 224 of the refrigeration circuit 14 and the air handler 20 to exchange heat between the interior space(s) 32 and the refrigerant. Likewise, the working fluid 244 may circulate between the first heat exchanger 222 of the refrigeration circuit 14 and the ambient heat exchange assembly 242 to exchange heat between the refrigerant and the ambient environment 33.

[0075] In some embodiments, the ambient heat exchange assembly 242 comprises one or more heat exchangers (e.g., water cooling towers, radiators, fin-fan coolers, etc.) that are configured to transfer heat between the ambient environment 33 and the working fluid 244. In some embodiments, such as in the case of air-cooled chillers (described in more detail hereinafter), the ambient heat exchange assembly 242 may be integrated and combined with the first heat exchanger 222 so that heat is directly exchanged between the refrigerant and an airflow that is sourced from and provided back to the ambient environment.

[0076] The working fluid 244 may be similar to the heat transfer fluid flowing along fluid circuit 15. Thus, the working fluid 244 may comprise water or any other suitable aqueous mixture, such as a water-glycol mixture. Alternatively, the working fluid 244 may comprise air. When the working fluid 244 is water (or another aqueous mixture), the chiller 12 may be referred to as a “water-cooled” chiller, and when the working fluid 244 is air, the chiller 12 may be referred to as an “air-cooled” chiller.

[0077] In addition to the first heat exchanger 222 and the second heat exchanger 224, the refrigeration circuit 14 may include a compressor 226 (or one or more compressors 226 in some embodiments) and an expansion valve 230. The compressor 226 and expansion valve 230 may be in fluid communication with the first heat exchanger 222 and second heat exchanger 224 along the refrigerant circuit 14. During operations, the refrigeration circuit 14 may be operated to circulate the refrigerant in a first direction shown in FIG. 1 so as to transfer heat from the interior space(s) 32 to the ambient environment 33 (e.g., via the ambient heat exchange assembly 242). Such operation may be referred to herein as a “cooling mode” operation.

[0078] Specifically, in the cooling mode operation shown in FIG. 5, the refrigerant (which may be in a vapor or semi-vapor state) may be compressed by the compressor 226 and delivered to the first heat exchanger 222 via the refrigerant circuit 14. Within the first heat exchanger 222, heat is transferred from the refrigerant to the working fluid 244, which cools the refrigerant and at least partially condenses the refrigerant to a liquid. Thus, in the cooling mode operation of FIG. 5, the first heat exchanger 222 may be referred to as a “condenser.” Heat is then transferred from the heated working fluid 244 to the ambient environment 33 via the ambient heat exchange assembly 242 as previously described.

[0079] The condensed refrigerant is then expelled from the first heat exchanger 222 and flowed to the second heat exchanger 224 via the expansion valve 230. The expansion valve 230 may be positioned between the first heat exchanger 222 and second heat exchanger 224 along the refrigerant circuit 14. The expansion valve 230 may be actuated or configured so as to controllably expand and therefore cool the refrigerant upstream of the second heat exchanger 224.

[0080] The expanded and cooled refrigerant is then flowed to the second heat exchanger 224. Within the second heat exchanger 224, heat is transferred from the heat transfer fluid flowing along fluid circuit 15 to the refrigerant, which vaporizes (or at least partially vaporizes) the refrigerant. Thus, in the cooling mode operation of FIG. 5, the second heat exchanger 224 may be referred to as an “evaporator.” The cooled heat transfer fluid is then circulated to the air handler 20 to cool the interior space(s) 32 as previously described.

[0081] While not shown, in some embodiments, the refrigeration circuit 14 may circulate the refrigerant in a second, opposite direction than that shown in FIG. 5 so as to transfer heat from the ambient environment 33 to the interior space(s) 32 via the ambient heat exchange assembly 242 and the fluid circuit 15. Such operation may be referred to herein as a “heating mode” operation, and a refrigeration circuit 14 that is configured to operate in the heating mode may be referred to as a “heat pump.” During a heating mode operation of the refrigeration circuit 14, the first heat exchanger 222 may function as an “evaporator” (which vaporizes the refrigerant) and the second heat exchanger 224 may function as a “condenser” (which condenses the refrigerant).

[0082] The operation of the chiller 12 may be adjusted so as to provide different output cooling (or heating) capacities to the heat transfer fluid of the fluid circuit 15 during operations. Specifically, the mass flow rate of refrigerant flowing along the refrigerant circuit 14 may be adjusted (e.g., via adjustments to the operating speed of the compressor 226 and corresponding adjustments to the opening position of the expansion valve 230) to thereby change the rate of thermal heat transfer between the refrigerant and the heat transfer fluid of fluid circuit 15. In some embodiments, the chiller 12 may be operated at a lower output cooling capacity (e.g., by lowering the speed of the compressor 226) when the cooling demands of the interior space(s) 32 are lower.

[0083] As explained above and reiterated below, the present disclosure includes, without limitation, the following example implementations.

[0084] Clause 1. A method of controlling a climate control system, the method includes (a) setting a first target for a performance metric for an airflow through an air handler of a climate control system, (b) setting a second target for a heat transfer rate for a coil of the air handler based on the first target, and (c) adjusting a flow rate of heat transfer fluid through the coil to reduce an error associated with the second target.

[0085] Clause 2. The method of clause 1, wherein the performance metric comprises a temperature associated with the airflow.

[0086] Clause 3. The method of clause 2, wherein (a) comprises setting the first target for a dry bulb temperature of the airflow leaving the air handler.

[0087] Clause 4. The method of clause 2, wherein (a) comprises setting the first target for a temperature of ducting that receives the airflow from the air handler.

[0088] Clause 5. The method of clause 4, wherein (a) comprises setting the first target above a dewpoint of air surrounding an outside of the ducting.

[0089] Clause 6. The method of clause 2, wherein (c) comprises:

[0090] (c1) increasing the flow rate of the heat transfer fluid through the coil to increase the heat transfer rate through the coil and thereby decrease the temperature associated with the airflow; or

[0091] (c2) decreasing the flow rate of the heat transfer fluid through the coil to decrease the heat transfer rate through the coil and thereby increase the temperature associated with the airflow.

[0092] Clause 7. The method of clause 1, wherein the performance metric comprises a relative humidity of the airflow upstream of the air handler.

[0093] Clause 8. The method of clause 7, wherein (a) comprises setting the first target at or below a dewpoint temperature of the airflow upstream of the air handler.

[0094] Clause 9. A climate control system for conditioning an interior space, the climate control system includes a chiller that is configured to exchange heat with a flow of heat transfer fluid, an air handler including a coil that is configured to receive the flow of heat transfer fluid therethrough, ducting coupled to the air handler that is configured to circulate an airflow between the interior space and the air handler, and one or more controllers that are configured to: set a first target for a performance metric for the airflow based on a desired climate parameter for the interior space; set a second target for a heat transfer rate for the coil of the air handler based on the first target; and adjust a flow rate of heat transfer fluid through the coil to reduce an error associated with the second target.

[0095] Clause 10. The climate control system of clause 9, further including a first temperature sensor that is configured to detect a temperature of the heat transfer fluid emitted from the coil, wherein the one or more controllers are configured to determine the heat transfer rate for the coil based at least in part on an output from the first temperature sensor.

[0096] Clause 11. The climate control system of clause 10, further including a valve coupled between the chiller and the coil of the air handler, wherein the one or more controllers are configured to adjust the flow rate of the heat transfer fluid through the coil by adjusting a position of the valve.

[0097] Clause 12. The climate control system of clause 11, further including a second temperature sensor that is configured to detect a temperature of the airflow discharged from the air handler, wherein the one or more controllers are configured to set the first target for the performance metric as a target for the temperature of the airflow discharged from the air handler.

[0098] Clause 13. The climate control system of clause 11, further including a third temperature sensor that is configured to detect a temperature of the ducting downstream of the air handler, wherein the one or more controllers are configured to set the first target for the performance metric as a target for the temperature of the ducting downstream of the air handler.

[0099] Clause 14. The climate control system of clause 13, wherein the one or more controllers are configured to set the first target so that the temperature of the ducting downstream of the air handler is maintained above a dewpoint for air surrounding an outside of the ducting.

[0100] Clause 15. The climate control system of clause 11, further including a humidity sensor that is configured to detect a relative humidity of the airflow upstream of the air handler, wherein the one or more controllers are configured to set the first target as a temperature of the airflow that is at or below a dewpoint temperature of the airflow based at least in part on an output from the humidity sensor.

[0101] Clause 16. The climate control system of clause 11, wherein the one or more controllers are further configured to:

[0102] increasing the flow rate of the heat transfer fluid through the coil to increase the heat transfer rate through the coil and thereby decrease the temperature associated with the airflow; or

[0103] decreasing the flow rate of the heat transfer fluid through the coil to decrease the heat transfer rate through the coil and thereby increase the temperature associated with the airflow.

[0104] Clause 17. The climate control system of clause 11, wherein the performance metric comprises a relative humidity of the airflow upstream of the air handler.

[0105] Clause 18. The climate control system of clause 9, wherein the one or more controllers are further configured to:

[0106] setting the first target at or below a dewpoint temperature of the airflow upstream of the air handler.

[0107] Clause 19. A non-transitory, machine-readable medium comprising instructions, which when executed by one or more processors, cause the one or more processors to:

[0108] (a) set a first target for a performance metric for an airflow through an air handler of a climate control system; (b) set a second target for a heat transfer rate for a coil of the air handler based on the first target; and (c) adjust a flow rate of heat transfer fluid through the coil to reduce an error associated with the second target.

[0109] Clause 20. The non-transitory, machine-readable medium of clause 19, wherein the performance metric comprises a temperature associated with the airflow.

[0110] Clause 21. The non-transitory, machine-readable medium of clause 19, wherein (a) comprises set the first target for a dry bulb temperature of the airflow leaving the air handler.

[0111] Clause 22. The non-transitory, machine-readable medium of clause 20, wherein (a) comprises set the first target for a temperature of ducting that receives the airflow from the air handler.

[0112] Clause 23. The non-transitory, machine-readable medium of clause 22, wherein (a) comprises set the first target above a dewpoint of air surrounding an outside of the ducting.

[0113] Clause 24. The non-transitory, machine-readable medium of clause 23, wherein (c) includes (c1) increase the flow rate of heat transfer fluid through the coil to increase the heat transfer rate through the coil and thereby decrease the temperature associated with the airflow; or (c2) decrease the flow rate of heat transfer fluid through the coil to decrease the heat transfer rate through the coil and thereby increase the temperature associated with the airflow.

[0114] Clause 25. The non-transitory, machine-readable medium of clause 19, wherein the performance metric comprises a relative humidity of the airflow upstream of the air handler.

[0115] Clause 26. The non-transitory, machine-readable medium of clause 25, wherein (a) comprises set the first target below a dewpoint temperature of the airflow upstream of the air handler.

[0116] Embodiments disclosed herein provide systems and methods for more precise control of the operation a chiller system. Specifically, in some embodiments, an air handler of the chiller system may include a heat transfer coil (or “coil”) and one or more controllers that are configured to control the heat transfer rate in the coil by precisely controlling a flow rate of the heat transfer fluid therethrough based at least in part on a total temperature change for the heat transfer fluid across the coil. The control of the heat transfer rate may in turn be controlled based on one or more other performance metrics for the airflow also circulating through the air handler. Thus, control of the heat transfer rate of the coil in the air handler may be used as a proxy for controlling the one or more other performance metric. Without being limited to this or any other theory, control of the heat transfer rate of the coil according to embodiments disclosed herein may provide a more precise and consistent method for adjusting the thermal capacity delivered to the interior space by the chiller system. As a result, this relatively precise control of the heat transfer rate through the coil may allow for enhanced thermal capacity performance from the air handler without necessitating increased infrastructure capacities(e.g., via larger piping diameters, more and / or larger pumps, etc.). Therefore, use of at least some embodiments disclosed herein may allow for enhanced operation and performance of existing chillers with minimal additional retrofit.

[0117] The preceding discussion is directed to various exemplary embodiments. However, one of ordinary skill in the art will understand that the examples disclosed herein have broad application, and that the discussion of any embodiment is meant only to be exemplary of that embodiment, and not intended to suggest that the scope of the disclosure, including the claims, is limited to that embodiment.

[0118] The drawing figures are not necessarily to scale. Certain features and components herein may be shown exaggerated in scale or in somewhat schematic form and some details of conventional elements may not be shown in interest of clarity and conciseness.

[0119] In the discussion herein and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . .” Also, the term “couple” or “couples” is intended to mean either an indirect or direct connection. Thus, if a first device couples to a second device, that connection may be through a direct connection of the two devices, or through an indirect connection that is established via other devices, components, nodes, and connections. In addition, as used herein, the terms “axial” and “axially” generally mean along or parallel to a given axis (e.g., central axis of a body or a port), while the terms “radial” and “radially” generally mean perpendicular to the given axis. For instance, an axial distance refers to a distance measured along or parallel to the axis, and a radial distance means a distance measured perpendicular to the axis. Further, when used herein (including in the claims), the words “about,”“generally,”“substantially,”“approximately,” and the like, when used in reference to a stated value mean within an approximate range of plus or minus 10% of the stated value.

[0120] While exemplary embodiments have been shown and described, modifications thereof can be made by one skilled in the art without departing from the scope or teachings herein. The embodiments described herein are exemplary only and are not limiting. Many variations and modifications of the systems, apparatus, and processes described herein are possible and are within the scope of the disclosure. Accordingly, the scope of protection is not limited to the embodiments described herein, but is only limited by the claims that follow, the scope of which shall include all equivalents of the subject matter of the claims. Unless expressly stated otherwise, the steps in a method claim may be performed in any order. The recitation of identifiers such as (a), (b), (c) or (1), (2), (3) before steps in a method claim are not intended to and do not specify a particular order to the steps, but rather are used to simplify subsequent reference to such steps.

Examples

Embodiment Construction

[0014]A climate control system, such as a chiller system, may include a refrigerant circuit and one or more separate and additional fluid circuits for exchanging heat between an interior space and an ambient environment. For instance, the interior space may be one or more interior spaces of a building or other structure, and the ambient environment may be the outdoor environment at least partially surrounding the building. Specifically, a chiller system may include a fluid circuit that is configured to transfer heat between the refrigerant circuit and the interior space(s). The fluid circuit may circulate a heat transfer fluid in a substantially singular phase (e.g., a liquid phase) between a first heat exchanger positioned along the refrigerant circuit and a second heat exchanger that is configured to exchange heat between the heat transfer fluid and an airflow that is circulated through the interior space(s). Because this second heat exchanger is configured to transfer heat betwee...

Claims

1. A method of controlling a climate control system, the method comprising:(a) setting a first target for a performance metric for an airflow through an air handler of a climate control system;(b) setting a second target for a heat transfer rate for a coil of the air handler based on the first target; and(c) adjusting a flow rate of heat transfer fluid through the coil to reduce an error associated with the second target.

2. The method of claim 1, wherein the performance metric comprises a temperature associated with the airflow.

3. The method of claim 2, wherein (c) comprises:(c1) increasing the flow rate of the heat transfer fluid through the coil to increase the heat transfer rate through the coil and thereby decrease the temperature associated with the airflow; or(c2) decreasing the flow rate of the heat transfer fluid through the coil to decrease the heat transfer rate through the coil and thereby increase the temperature associated with the airflow.

4. The method of claim 1, wherein the performance metric comprises a relative humidity of the airflow upstream of the air handler.

5. The method of claim 4, wherein (a) comprises setting the first target at or below a dewpoint temperature of the airflow upstream of the air handler.

6. A climate control system for conditioning an interior space, the climate control system comprising:a chiller that is configured to exchange heat with a flow of heat transfer fluid;an air handler including a coil that is configured to receive the flow of heat transfer fluid therethrough;ducting coupled to the air handler that is configured to circulate an airflow between the interior space and the air handler; andone or more controllers that are configured to:set a first target for a performance metric for the airflow based on a desired climate parameter for the interior space;set a second target for a heat transfer rate for the coil of the air handler based on the first target; andadjust a flow rate of heat transfer fluid through the coil to reduce an error associated with the second target.

7. The climate control system of claim 6, further comprising:a first temperature sensor that is configured to detect a temperature of the heat transfer fluid emitted from the coil,wherein the one or more controllers are configured to determine the heat transfer rate for the coil based at least in part on an output from the first temperature sensor.

8. The climate control system of claim 7, further comprising:a valve coupled between the chiller and the coil of the air handler,wherein the one or more controllers are configured to adjust the flow rate of the heat transfer fluid through the coil by adjusting a position of the valve.

9. The climate control system of claim 7, further comprising:a second temperature sensor that is configured to detect a temperature of the airflow discharged from the air handler,wherein the one or more controllers are configured to set the first target for the performance metric as a target for the temperature of the airflow discharged from the air handler.

10. The climate control system of claim 9, further comprising:a humidity sensor that is configured to detect a relative humidity of the airflow upstream of the air handler,wherein the one or more controllers are configured to set the first target as a temperature of the airflow that is at or below a dewpoint temperature of the airflow based at least in part on an output from the humidity sensor.

11. The climate control system of claim 9, wherein the one or more controllers are further configured to:increasing the flow rate of the heat transfer fluid through the coil to increase the heat transfer rate through the coil and thereby decrease the temperature associated with the airflow; ordecreasing the flow rate of the heat transfer fluid through the coil to decrease the heat transfer rate through the coil and thereby increase the temperature associated with the airflow.

12. The climate control system of claim 9, wherein the performance metric comprises a relative humidity of the airflow upstream of the air handler.

13. The climate control system of claim 7, wherein the one or more controllers are further configured to:setting the first target at or below a dewpoint temperature of the airflow upstream of the air handler.

14. A non-transitory, machine-readable medium comprising instructions, which when executed by one or more processors, cause the one or more processors to:(a) set a first target for a performance metric for an airflow through an air handler of a climate control system;(b) set a second target for a heat transfer rate for a coil of the air handler based on the first target; and(c) adjust a flow rate of heat transfer fluid through the coil to reduce an error associated with the second target.

15. The non-transitory, machine-readable medium of claim 14, wherein the performance metric comprises a temperature associated with the airflow.

16. The non-transitory, machine-readable medium of claim 14, wherein (c) comprises:(c1) increase the flow rate of heat transfer fluid through the coil to increase the heat transfer rate through the coil and thereby decrease the temperature associated with the airflow; or(c2) decrease the flow rate of heat transfer fluid through the coil to decrease the heat transfer rate through the coil and thereby increase the temperature associated with the airflow.

17. The non-transitory, machine-readable medium of claim 14, wherein the performance metric comprises a relative humidity of the airflow upstream of the air handler.

18. The non-transitory, machine-readable medium of claim 17, wherein (a) comprises set the first target below a dewpoint temperature of the airflow upstream of the air handler.

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