Refrigeration systems including pressure exchangers and controllable elements

Abstract

A system includes a pressure exchanger (PX) configured to receive a first fluid, receive a second fluid, and exchange pressure between the first fluid and the second fluid. The system further includes a heat exchanger configured to receive the second fluid from the PX via a first inlet, receive a third fluid via a second inlet, and exchange heat between the second fluid and the third fluid. The system further includes a first compressor configured to receive the third fluid from the first heat exchanger.

Description

REFRIGERATION SYSTEMS INCLUDING PRESSURE EXCHANGERS ANDCONTROLLABLE ELEMENTSTECHNICAL FIELD

[0001] The present disclosure relates to control of systems, and, more particularly, control of refrigeration and heat pump systems that include pressure exchangers.BACKGROUND

[0002] Systems use fluids at different pressures. Systems use pumps and / or compressors to increase pressure of fluid. Energy usage of a fluid handling system may be largely consumed by pumps and / or compressors increasing fluid pressure.BRIEF DESCRIPTION OF THE DRAWINGS

[0003] The present disclosure is illustrated by way of example, and not by way of limitation in the figures of the accompanying drawings.

[0004] FIG. 1A is a schematic diagram of a fluid handling system that includes a hydraulic energy transfer system, according to some embodiments.

[0005] FIG. IB is a schematic diagram of a fluid handling system including a hydraulic energy transfer system, according to some embodiments.

[0006] FIGS. 2A-E are exploded perspective views of pressure exchangers (PXs), according to some embodiments.

[0007] FIG. 3 A is a schematic diagram of a fluid handling system including a PX and heat exchangers for exchanging heat between streams of working fluid, according to some embodiments.

[0008] FIG. 3B is a schematic diagram of a fluid handling system that includes a pressure exchanger and a low-pressure valve, according to some embodiments.

[0009] FIG. 3C is a schematic diagram of a fluid handling system that includes a subcooler and a superheater, according to some embodiments

[0010] FIG. 4A is a schematic diagram of a fluid handling system including a PX, an auxiliary gas cooler, and various controllers and other components for providing control of the fluid handling system, according to some embodiments.

[0011] FIG. 4B is a schematic diagram of a fluid handling system including sensors and controllers, according to some embodiments.

[0012] FIG. 5A is a flow diagram of a method for providing control of a fluid handling system, according to some embodiments.

[0013] FIG. 5B is a flow diagram of a method for providing control of a refrigeration system, according to some embodiments.

[0014] FIG. 6 is a block diagram illustrating a computer system, according to certain embodiments.DETAILED DESCRIPTION OF EMBODIMENTS

[0015] Embodiments described herein are related to architectures of refrigeration and / or heat pump systems that include pressure exchangers, and control of these systems. For example, architectures may include refrigeration systems, heat pump systems, pressure exchanger systems, fluid handling systems that include a pressure exchanger, heat transfer systems, control systems for carbon dioxide (CO2) refrigeration systems integrated with rotary pressure exchanger, etc., as well as control of such systems. In particular, system architectures as well as associated control modules for controlling, maintaining, adjusting, etc. operation of systems including one or more pressure exchangers are described.

[0016] Systems may use fluids at different pressures. A supply of a fluid to a system may be at lower pressure, and one or more portions of the system may operate at higher pressures. A system may include a closed loop with various fluid pressures maintained in different portions of the loop. These systems may include refrigeration systems, heat pump systems, energy generation systems, fluid transportation systems, etc. Pumps or compressors may be used to increase pressure of fluids of such systems.

[0017] Conventionally, heat transfer systems (e.g., refrigeration systems, heat pump systems, reversible heat pump systems, or the like) use pumps or compressors to increase the pressure of a fluid (e.g., a refrigeration fluid such as carbon dioxide (CO2), R-744, R-134a, hydrocarbons, hydrofluorocarbons (HFCs), hydrochlorofluorocarbons (HCFCs), ammonia (NH3), refrigerant blends, R-407A, R-404A, etc.). Conventionally, separate pumps or compressors mechanically coupled to motors are used to increase pressure of the fluid in any portion of a system including an increase in fluid pressure. Pumps and compressors, especially those that operate over a large pressure differential (e.g., cause a large pressure increase in the fluid), require large quantities of energy. Conventional systems thus expend large amounts of energy increasing the pressure of the fluid (via the pumps or compressors driven by the motors). Additionally, conventional heat transfer systems decrease the pressure of the fluid through expansion valves and / or heat exchangers (e.g., condensers and / or evaporators, etc.). Conventional systems inefficiently increase pressure of fluid and decrease pressure of the fluid. This is wasteful in terms of energy used to run the conventional systems(e.g., energy used to repeatedly increase the pressure of the refrigeration fluid to cause increase or decrease of temperature of the surrounding environment).

[0018] The systems, devices, and methods of the present disclosure enable operation and control of systems (e.g., fluid handling systems, heat transfer systems, refrigeration systems, heat pump systems, cooling systems, heating systems, etc.) including one or more pressure exchangers (PXs). In a system, a PX may be configured to exchange pressure between a first fluid (e.g., a high-pressure portion of a refrigeration fluid or working fluid in a refrigeration cycle) and a second fluid (e.g., a low-pressure portion of the refrigeration fluid in the refrigeration cycle). The PX may receive the first fluid (e g., a portion of the refrigeration fluid at high pressure) via a first inlet (e.g., a high-pressure inlet) and a second fluid (e.g., a portion of the refrigeration fluid at a low pressure) via a second inlet (e.g., a low-pressure inlet). When entering the PX, the first fluid may be of a higher pressure than the second fluid. The PX may exchange pressure between the first fluid and the second fluid. The first fluid may exit the PX via a first outlet (e.g., a low-pressure outlet) and the second fluid may exit the PX via a second outlet (e.g., a high-pressure outlet). When exiting the PX, the second fluid may have a higher pressure than the first fluid (e.g., pressure has been exchanged between the first fluid and the second fluid).

[0019] In some systems, fluid may be pumped, compressed, have pressure increased, or the like at various portions of the fluid handling system. For example, a main compressor (or set of compressors) may perform work to increase pressure of low-pressure fluid to high- pressure fluid, and various other compressors or boosters may be utilized to provide auxiliary adjustments to pressure at other points of the fluid handling system. In some embodiments, one or more adjustments to a fluid flow path may be introduced to reduce a number of pumps or compressors needed, e.g., by utilizing a PX to perform compression conventionally performed by a booster pump. Further, a PX may be utilized to reduce pressure of working fluid at some points of a fluid handling system, e.g., a PX may be used to replace one or more expansion valves, while utilizing the lost pressure to pressurize other fluid streams.

[0020] In some embodiments, a heat transfer system (e.g., refrigeration system, heat pump system, etc.) may target controlled operating conditions. For example, a refrigeration system may target a particular temperature of a refrigerated zone (e.g., for safe storage of perishable materials such as food, medication, scientific or research materials, or the like); a heat pump system may target a comfortable interior temperature for a home; a system may target a rate of heat exchange between the system and the environment; one or more portions of a system may target an operating temperature, pressure, fluid density, or the like; etc. Operationalparameters to maintain target conditions may be dependent on many factors, e.g., ambient temperature; mass, type, and initial temperature of material in a temperature-controlled area; frequency of exchange of material and / or energy between a controlled area and the ambient environment; and the like.

[0021] In some embodiments, the PX may be operable at a range of operating speeds. For example, a rotary PX may be operable at a variety of rotational speeds, a reciprocating PX may be operable at a variety of cycle frequencies, or the like. The PX may be coupled to a motor. The motor may be configured to control an operating speed of the PX. The operating speed of the PX may have an impact on fluid flow rate, fluid pressure in various portions of the fluid handling system, etc. In some embodiments, the motor may drive the PX, e.g., if faster flow rate through the PX is targeted, the motor may speed up operation of the PX. In some embodiments, the motor may serve to inhibit the PX, e.g., if slower flow rate through the PX is targeted, the motor may inhibit motion of the PX to maintain a desired flow rate. A controller may be operatively coupled to the motor of the PX. The controller may receive data collected from one or more parts of the fluid handling system, e.g., pressure data indicative of fluid pressure associated with (e.g., in, exiting from) a condenser of the fluid handling system, flow rate data indicative of flow rate through a portion of the fluid handling system, or the like. The controller may generate a control signal for the motor based on the data received indicative of one or more operating conditions of the fluid handling system. The motor may be configured to adjust an operating speed of the PX based on the control signal.

[0022] In some embodiments, operating speed of the PX may be utilized to maintain one or more conditions of the fluid system. For example, the PX speed may be selected to maintain a target fluid pressure at a component upstream of the PX. The PX speed may further impact other conditions of the system but may be at least partially unavailable for adjustment due to the impact of the PX speed on multiple conditions and components of the system. Additional control methods may be utilized in maintaining one or more target conditions of a fluid system, that may be further affected by an operating speed of the PX.

[0023] In some embodiments, the fluid system may include one or more control valves, that may be opened or closed to enable a target fluid flow rate, a target upstream fluid pressure, a target downstream fluid pressure, or the like. A control valve may be included in a fluid system, coupled to a high-pressure outlet of the PX. For example, a fluid may leave a high- pressure outlet of the PX, pass through an auxiliary gas cooler, and be provided to a control valve. The control valve may have an adjustable opening, that is adjusted based on one ormore inputs, to maintain a target condition of the fluid system. The control valve opening may be adjusted to maintain a target travel distance of the PX.

[0024] Travel distance is a measure of fluid flow into or out of ducts of the PX. For example, fluid may flow from a first inlet into a duct and exchange pressure with a second fluid that entered the duct from an inlet disposed at the opposite side of the duct. The fluid may then, after exchanging pressure, be removed via an outlet disposed at the same side of the duct that the fluid entered. The travel distance is a measure of how far into the duct the first fluid flows before retreating back to the outlet. Travel distance indicates a volumetric flow through the PX, e.g., based on rotational speed of the PX, number of ducts in the PX, and total duct volume of the PX. Two inlets of the PX may have their own associated travel distances. For example, in operation the PX may operate at a first low-pressure travel distance, associated with travel of a fluid provided at a low-pressure inlet of the PX, and a second high-pressure travel distance, associated with travel of a fluid provided at a high- pressure inlet of the PX. A travel distance target may be chosen based on target volume flow through the PX, target energy efficiency, target pressure exchange efficiency, target mixing of the first and second fluids, or the like.

[0025] One or more travel distances of the PX may be adjusted and / or maintained via adjusting operation of components of a fluid transfer system including the PX. For example, the low-pressure inlet travel distance (e.g., a volume of fluid provided to the PX low-pressure inlet as compared to a working volume of the PX) may be maintained by adjusting the opening of the control valve coupled to the high-pressure outlet of the PX. The working volume of the PX depends on the speed of operation of the PX. For example, in a rotary PX, as rotational speed increases, the number of ducts of the PX utilized in a period of time increases. The control valve may be configured to be controlled based on the PX speed to maintain a target low-pressure inlet travel distance in the PX. Further signals may be taken into account in setting an opening of the control valve, such as total system load (e.g., total fluid flow through the system), temperature at one or more gas coolers, temperature of fluid in one or more portions of the fluid handling system, etc.

[0026] In some embodiments, the fluid system may include one or more heat exchangers, e.g., to exchange heat between fluids at different points of a fluid handling system. For example, the fluid handling system may include a heat exchanger for cooling a main flow of fluid from a main gas cooler. A portion of fluid provided by the gas cooler may be provided to a cooling fluid channel of the heat exchanger to cool a main portion of fluid. A portion of fluid provided to each fluid channel may be determined by a control valve. A target coolingcondition may be monitored, and the portion of fluid provided to the primary or secondary channels of the heat exchanger may be adjusted to achieve a target cooling condition, such as a target subcooling of main fluid provided to the heat exchanger In another example, a fluid handling system may include a heat exchanger to exchange heat between a high-pressure fluid exiting the high-pressure outlet of the PX, and another fluid, such as fluid being provided to one or more compressors of the fluid handling system. Such an arrangement may increase the proportion of liquid in a receiver coupled to the high-pressure outlet of the PX (e.g., reducing pumping requirements to compress flash gas, improving efficiency of the system) and may increase temperature of a fluid provided to one or more compressors (e g., compressors which may be damaged if liquid is provided at the compressor suction, protecting the compressor(s) from damage). Such a heat exchanger may provide superheat (e.g., additional heat beyond that required to vaporize) to fluid to be provided to one or more compressors.

[0027] In some embodiments, a superheat heat exchanger may obtain fluid from the high- pressure outlet of the PX, and exchange heat in that fluid with fluid being provided to a compressor of the system. In a first example, the superheater may be coupled to fluid provided to an inlet of a main compressor, e.g., all working fluid provided to the main compressor may be heated by the superheater. In some embodiments, only some combination of flow paths may pass through the super heater, e.g., any combination of flash gas, output of one or more evaporators (before or after any additional compressors) including medium temperature evaporators and low temperature evaporators, etc.

[0028] In some embodiments, the fluid handling system may include a control valve associated with a fluid flow path from the high-pressure outlet of the PX to a receiver. This flow path may include one or more components for reducing temperature of the fluid, e.g., an auxiliary gas cooler, a heat exchanger (such as the superheat heat exchanger described above), or the like. The control valve associated with the auxiliary gas cooler may be opened to determine an amount of fluid that passes through the auxiliary gas cooler, to determine a travel distance of the PX, etc. The control valve associated with this flow path may be opened an amount based on an opening of another valve on the flow path, e.g., a control valve configured to determine a portion of fluid provided to a secondary channel of a heat exchanger of the fluid handling system. The control valve associated with this flow path may be opened to enable flow through the valve matching flow through another valve controlled based on other criteria of the fluid handling system. The control valve associated with this flow path may be operated based on indications of fluid mass flow, including measured flow,flow derived from fluid properties and one or more component operating speeds (e.g., a low- pressure booster associated with a low-pressure inlet, PX operating speed, etc.), flow equivalency based on properties of fluids at various locations of the fluid handling system, etc.

[0029] In some embodiments, the fluid handling system may include a mechanism for adjusting heat transfer efficiency of one or more heat exchanger, condensers, gas coolers, or the like. For example, an auxiliary gas cooler may include or be associated with one or more fans for increasing heat transfer from the gas cooler to an environment proximate the gas cooler (e g., an ambient environment). Activation and / or operation of a device adjusting efficiency of heat transfer (e.g., adjusting a fan speed of the auxiliary gas cooler) may be based on temperature of fluid output by the gas cooler. In some embodiments, actions may be taken to achieve and / or maintain a target temperature of fluid output by the auxiliary gas cooler. The target temperature may be based on ambient temperature, e.g., a target fluid temperature after the fluid has passed through the gas cooler may be within a target temperature of the ambient temperature, such as within 5 degrees of the ambient temperature. The target temperature may be based on fluid temperature elsewhere in the fluid handling system, such as fluid output by a main gas cooler. There may be additional architecture, sensors, processing devices, or the like used for maintaining a target or optimal condition of fluid output by the main gas cooler, and a smaller number of sensors or other architecture may be utilized to match fluid output by the auxiliary gas cooler to the fluid output by the main gas cooler.

[0030] In some embodiments, control of a portion of fluid provided to the main and secondary fluid channels of a heat exchanger may be based, instead of other conditions or in addition to other conditions, on conditions of a receiver. For example, subcooling provided to a main flow of fluid in a heat exchanger may decrease an amount of flash gas that accumulates in the receiver, e.g., by reducing temperature of fluid provided to the receiver. In some embodiments, a flash gas valve may be utilized to allow flash gas from the receiver to be directed to other components of the fluid handling system, such as a main compressor. Subcooling of a heat exchanger may be controlled (e.g., by adjusting a portion of fluid provided to main and secondary channels of the heat exchanger) based on reducing flash gas in the receiver. Subcooling of a heat exchanger may be controlled based on sensor readings and / or control signals provided to a flash gas valve, which in turn may be based on flash gas in the receiver. In some embodiments, such a subcooling heat exchanger may obtain as input to the secondary channel (e.g., the channel including fluid to absorb heat from fluid of theprimary channel) fluid output from the gas cooler, or fluid output from the subcooling heat exchanger.

[0031] In some embodiments, a pressure differential may be maintained between a receiver and a low-pressure subsystem (e.g., low-pressure inlet and low-pressure outlet) of the PX. A control valve may be installed between the low-pressure outlet of the PX and the receiver. A controller may receive an indication of a pressure differential, and may cause a control signal to be provided to the control valve to adjust operation of the control valve, e.g., to achieve a target pressure differential.

[0032] Systems including a control valve for maintaining a pressure differential between a low-pressure subsystem of the PX and the receiver may be combined with systems including a subcooler (which may have a second channel coupled to receive fluid either before or after the fluid flows through the primary channel of the subcooler), including a low-pressure booster, including an auxiliary gas cooler, including a superheater, etc. Combinations of these features may be included, e g., to tune properties of the system for a target use.

[0033] Systems, devices, and methods of the present disclosure provide advantages over conventional solutions. Systems of the present disclosure reduce energy consumption compared to conventional systems, e.g., systems that do not include a PX. For example, use of a PX in a heat transfer system of the present disclosure may recover energy stored as pressure and transfer that energy back into the system, reducing the energy cost of operating the heat transfer system. Reduction of energy cost may enable lower compressor speed or power consumption, or less expensive, smaller, and / or lower power compressors to be used in the system.

[0034] Various controllers employed by the system may increase energy efficiency of the system by, for example, minimizing work performed by the compressor to maintain target conditions, for example target temperatures of refrigerated zones associated with the fluid handling system. For example, increased energy efficiency may be achieved by maximizing the transfer of pressure from the first fluid to the second fluid via the PX (e g., by adjusting fluid flow rates, fluid pressures, PX operating speed, or the like).

[0035] Systems of the present disclosure may reduce complexity of a fluid handling system, by reducing a number of pumps (e.g., boosters) included in the system. For example, architectures of the present disclosure may enable removal of one or more pumps or compressors, e.g., by allowing the PX to perform some pumping or compression operations that, in other architectures, may be performed by a booster. Reduction of a number of pumps or compressors may reduce an equipment cost of the system, reduce a number of componentsthat may be serviced, reduce a number of failure points for reducing system downtime or corrective or preventative maintenance, or the like. Specifically, some aspects of the present disclose include a subcooler, which may be utilized in architectures that do not include a low- pressure booster coupled to the low-pressure inlet of the PX.

[0036] Aspects of the present disclosure may improve efficiency of a fluid handling system by reducing pumping requirements on the system. For example, a feed flow provided to the receiver may include a higher proportion of liquid in architectures of the present disclosure, than in conventional systems. The higher liquid fraction may reduce requirements to compress flash gas to perform heat transfer operations, thus improving efficiency of the system. By providing high-temperature fluid form a high-pressure outlet of the PX to a superheater, auxiliary gas cooler, or other component, and reducing the temperature of that fluid before it is provided to the receiver, a higher mass fraction of liquid may be included in the receiver than in association with conventional architectures.

[0037] Systems of the present disclosure may reduce wear on components (e.g., pumps, compressors) compared to conventional systems. Introduction of a PX may reduce the pumping load on one or more pumps / compressors, e.g., may reduce a target pressure differential a compressor is to achieve. One or more controllers (e.g., control system) may improve operation of pumps and compressors by enabling operation at a target pumping speed, e.g., a pumping speed selected to meet target system output (e.g., maintain a target temperature in a heat transfer system) while protecting one or more components of the system (e.g., a minimum viable pumping speed).

[0038] Systems of the present disclosure may protect one or more components from damage. For example, a compressor of the system may be sensitive to the phase of material provided to the compressor (e.g., may be configured to compress a gas, may become damaged if supplied with liquid, etc.). A superheater may increase the temperature of a fluid provided to one or more compressors of the system. The superheater may receive high- temperature fluid from a high-pressure outlet of the PX. The high-temperature fluid may be provided to a superheater to exchange heat with a fluid to be provided to a compressor. The compressor may be less likely to be provided liquid in this case, e.g., the compressor may be protected from damaging input conditions. In other embodiments, a controller of the system may alter one or more operating parameters of the system (e.g., a fluid flow rate, a pumping speed, PX operating speed, control valve opening, etc.) to maintain a supply of gas to the compressor (e.g., by maintaining a target value of super heat of the gas). Systems of the present disclosure may allow for more flexibility in component selection for a fluid handlingsystem. For example, one or more controllers (e.g., control system) may be operatively coupled, and may work together to maintain one or more operating conditions. For example, a system may include multiple controllers (e.g., control system) operatively coupled to multiple components (e.g., configured to facilitate adjustment of one or more operating parameters of the components). Multiple control signals may be generated to achieve one or more target tasks, e g., temperature of a region associated with a heat transfer system may be maintained, and load on a pump may be kept within a target range. By utilizing multiple controllers of a system, such goals may be achievable, and / or the user may be able to use a greater selection of components in the system (e.g., may include a pump with a small manufacturer recommended operating pressure range in a system where pressure at the pump can be maintained within that range for a variety of operating conditions).

[0039] Systems of the present disclosure may enable control of one or more components of the fluid handling system with reducing sensor and / or control complexity compared to some conventional architectures. An auxiliary high-pressure valve may be included in the architecture coupled between a high-pressure outlet of the PX and the receiver (e.g., for regulated fluid flow through an auxiliary gas cooler, through a superheater, or the like). Control of the auxiliary high-pressure valve may be based on fluid properties being provided to the valve, fluid properties provided to a low-pressure inlet of the PX, or the like. In some cases, speed of operation of a component (e.g., PX operating speed, low-pressure booster operating speed, or the like) may be used to determine fluid properties, and to determine an opening of the auxiliary high-pressure valve. In some cases, opening of a different valve (e.g., opening of a valve determining fluid flow through a subcooler) may be used to determining opening of the auxiliary high-pressure valve, e.g., when fluid conditions at the subcooler are comparable to fluid conditions at the auxiliary high-pressure valve. In some embodiments, measurements from one or more flow meters may be utilized in determining opening of the auxiliary high-pressure valve. In some embodiments, sensors in place (e.g., for other purposes) on a PX subsystem of a refrigeration system (e.g., a parent rack) may be utilized, e.g., a temperature sensor at a gas cooler and a measurement of PX speed may be used to determining the opening of the auxiliary high-pressure valve. In some embodiments (e.g., including a superheater heat exchanger), fluid temperature at an inlet of a compressor and PX speed may be utilized in determining auxiliary high-pressure valve opening.

[0040] Although some embodiments of the present disclosure are described in relation to pressure exchangers, energy recovery devices, and hydraulic energy transfer systems, the current disclosure can be applied to other systems and devices (e.g., pressure exchanger thatis not isobaric, rotating components that are not a pressure exchanger, a pressure exchanger that is not rotary, systems that do not include pressure exchangers, etc.).

[0041] Although some embodiments of the present disclosure are described in relation to exchanging pressure between fluid used in fracing systems, desalinization systems, heat pump systems, and / or refrigeration systems, the present disclosure can be applied to other types of systems Fluids can refer to liquid, gas, transcritical fluid, supercritical fluid, subcritical fluid, and / or combinations thereof.

[0042] In some aspects of the present disclosure, a system includes a pressure exchanger (PX) configured to receive a first fluid, receive a second fluid, and exchange pressure between the first fluid and the second fluid. The system further includes a first heat exchanger configured to receive the second fluid from the PX via a first inlet, receive a third fluid via a second inlet, and exchange heat between the second fluid and the third fluid. The system further includes a first compressor configured to receive the third fluid from the first heat exchanger.

[0043] In some aspects of the present disclosure, a method includes obtaining, by a processing device, an indication of properties of working fluid of a refrigeration system provided to a low-pressure inlet of a PX. The method further includes generating a first control signal based on the indication of properties of the working fluid at the low-pressure inlet of the PX. The method further includes providing the control signal to a high-pressure control valve fluidly coupled between a high-pressure outlet of the PX and a receiver. The high-pressure control valve is configured to adjust operation of the high-pressure control valve based on the first control signal.

[0044] In some aspects of the present disclosure, a method includes obtaining, by a processing device, an indication of a pressure differential between a receiver of a refrigeration system and a low-pressure subsystem of a PX of the refrigeration system. The method further includes generating a first control signal based on the indication of the pressure differential. The method further includes providing the first control signal to a control valve. The control valve is fluidly coupled between a low-pressure outlet of the PX and the receiver. The control valve is configured to adjust operation of the control valve based on the first control signal.

[0045] FIG. 1A illustrates a schematic diagram of a fluid handling system 100A (e.g., heat transfer system, refrigeration system) that includes a hydraulic energy transfer system 110, according to certain embodiments.

[0046] In some embodiments, a hydraulic energy transfer system 110 includes a pressure exchanger (e.g., PX). The hydraulic energy transfer system 110 (e.g., PX, a collection of components including a PX, etc.) receives low pressure (LP) fluid in 120 (e g., via a low- pressure inlet) from an LP in system 122. The hydraulic energy transfer system 110 also receives high pressure (HP) fluid in 130 (e.g., via a high-pressure inlet) from HP in system 132. The hydraulic energy transfer system 110 (e.g., PX) exchanges pressure between the HP fluid in 130 and the LP fluid in 120 to provide LP fluid out 140 (e.g., via low-pressure outlet) to LP fluid out system 142 and to provide HP fluid out 150 (e.g., via high-pressure outlet) to HP fluid out system 152. Fluid handling system 100A includes protective and control components 182, e.g., the architecture is designed to include one or more components to improve operation and control compared to other PX fluid handling systems, such as other PX heat transfer or refrigeration systems. Protective and control components 182 may include one or more additional heat exchangers, e.g., for providing superheating of working fluid provided to compressors of fluid handling system 100A. Protective and control components 182 may include an auxiliary high-pressure valve and associated control architecture. Protective and control components 182 may include a valve for maintaining a pressure differential between a low-pressure subsystem of the PX and a receiver of fluid handling system 100A.

[0047] A controller may cause an adjustment of flowrates and / or conditions of fluids of HP fluid in 130 and LP fluid out 140 by one or more flow valves, pumps, motors, fans, and / or compressors (not illustrated). The controllers may be configured to cause various operations (e.g., of controllable components included in fluid handling system 100 A) to be performed. A controller may be configured to cause actuation of one or more valve. A controller may be configured to cause adjustments to speed of operation of one or more components. A controller may cause other operations of controllable components of fluid handling system 100A. The controllers may cause one or more valves to actuate. The controllers may activate, deactivate, or adjust operation of one or more pumps. Controllers may activate, deactivate, or adjust operation of components that adjust heat transfer to or from a working fluid of fluid handling system 100A. For example, controllers may activate fans that increase heat transfer from the working fluid to an ambient environment via one or more gas coolers of fluid handling system 100A.

[0048] In some embodiments, the hydraulic energy transfer system 110 includes a PX to exchange pressure between the HP fluid in 130 and the LP fluid in 120. In some embodiments, the PX is substantially or partially isobaric (e.g., an isobaric pressureexchanger (IPX)). The PX may be a device that transfers fluid pressure between HP fluid in 130 and LP fluid in 120 at efficiencies (e.g., pressure transfer efficiencies, substantially isobaric) in excess of approximately 50%, 60%, 70%, 80%, 90%, or greater (e g., without utilizing centrifugal technology). High pressure (e.g., HP fluid in 130, HP fluid out 150) refers to pressures greater than the low pressure (e.g., LP fluid in 120, LP fluid out 140). LP fluid in 120 of the PX may be pressurized and exit the PX at high pressure (e.g., HP fluid out 150, at a pressure greater than that of LP fluid in 120), and HP fluid in 130 may be at least partially depressurized and exit the PX at low pressure (e.g., LP fluid out 140, at a pressure less than that of the HP fluid in 130). The PX may operate with the HP fluid in 130 directly applying a force to pressurize the LP fluid in 120, with or without a fluid separator between the fluids. Examples of fluid separators that may be used with the PX include, but are not limited to, pistons, bladders, diaphragms, and / or the like.

[0049] In some embodiments, PXs may be rotary devices. Rotary PXs, such as those manufactured by Energy Recovery, Inc. of San Leandro, Calif., may not have any separate valves, since the effective valving action is accomplished internal to the device via the relative motion of a rotor with respect to end covers. In some embodiments, rotary PXs operate with internal pistons to isolate fluids and transfer pressure with relatively little mixing of the inlet fluid streams. In some embodiments, rotary PXs operate without internal pistons between the fluids.

[0050] In some embodiments, PXs may be reciprocating devices. Reciprocating PXs may include a piston moving back and forth in a cylinder for transferring pressure between the fluid streams. For example, a reciprocating PX may include one or more pressure exchange chambers. The pressure exchange chambers may each include a piston. First fluid at a high pressure may be allowed into one side of a pressure exchange chamber to transfer energy (e.g., via displacement of the piston) to a second fluid at a low pressure on the opposite side of the pressure exchange chamber. The first fluid, now at a low pressure, may then be allowed to drain from the pressure exchange chamber, as the second fluid, now at a high pressure, it utilized for operation of the fluid handling system (e.g., for desalinization, fracing, refrigeration, heat transfer, or the like). Low pressure second fluid may then be allowed to fill the second side of the pressure exchange chamber, and subsequently high pressure first fluid may be introduced into the first side of the pressure exchange chamber to transfer energy to another portion of the second fluid. A reciprocating device may include many pressure exchange chambers operating in a cycle for substantially continuous flow of high pressure second fluid from the device.

[0051] In some embodiments, PXs may be hydraulic turbocharger devices. A hydraulic turbocharger PX may introduce a first fluid at a high pressure to a chamber including a first impeller. The first high pressure fluid may cause the impeller to rotate by transferring energy from the first fluid to the impeller. The first impeller may be coupled to a shaft that is further coupled to a second impeller in a separate chamber. Rotation of the first impeller may cause rotation of the second impeller. The second impeller may be in contact with a second fluid at a low pressure. Rotation of the impeller may transfer energy to the second fluid (e.g., increase pressure of the second fluid).

[0052] Any PX or multiple PXs may be used in the present disclosure, such as, but not limited to, rotary PXs, reciprocating PXs, hydraulic turbocharger PXs, or any combination thereof. In addition, the PX may be disposed on a skid separate from the other components of a fluid handling system 100A (e.g., in situations in which the PX is added to an existing fluid handling system). For example, the PX may be fastened to a structure that can be moved from one site to another. The PX may be coupled to a system (e.g., pipes of a system, etc.) that has been built on-site. The structure to which the PX is fastened may be referred to as a ‘skid.’

[0053] In some embodiments, a motor 160 is coupled to hydraulic energy transfer system 110 (e.g., to a PX). In some embodiments, the motor 160 controls the speed of a rotor of the hydraulic energy transfer system 110 (e.g., to increase pressure of HP fluid out 150, to decrease pressure of HP fluid out 150, etc.). In some embodiments, motor 160 generates energy (e.g., acts as a generator) based on pressure exchanging in hydraulic energy transfer system 110. For example, a pressure differential (e.g., a difference between the pressure of LP fluid in 120 and HP fluid in 130) may drive rotation of a rotary PX, and motor 160 may introduce resistance to that rotation to both slow the rotation and generate electricity.Alternatively, the motor may act to slow the PX without generating electricity.

[0054] The hydraulic energy transfer system 110 may include a hydraulic turbocharger or hydraulic pressure exchanger, such as a rotating PX. The PX may include one or more chambers and / or channels (e.g., 1 to 100 channels) to facilitate pressure transfer between first and second fluids (e.g., gas, liquid, multi -phase fluid, supercritical fluid, etc.).

[0055] In some embodiments, hydraulic energy transfer system 110 may transfer energy (e.g., pressure) between two fluids of substantially different composition, phase, or the like. For example, a PX of hydraulic energy transfer system 110 may transfer pressure between a first fluid (e.g., pressure exchange fluid, such as a fluid of a first phase such as liquid or supercritical fluid, proppant free fluid, substantially proppant free fluid, lower viscosity fluid, fluid that has lower than a threshold amount of certain chemicals, etc.) and a second fluid thatmay be of a different phase, have a higher viscosity (e.g., be highly viscous), include more than a threshold amount of certain chemicals (e.g., corrosive chemicals), and / or contain solid particles (e g., frac fluid containing sand, proppant, powders, debris, ceramics, etc ). By transferring energy from one type of fluid to another, expensive components such as pumps may be protected from coming into contact with fluids that may be harmful to them, such as viscous, corrosive, or abrasive fluids, or fluids of a phase the components are not equipped to handle.

[0056] In some embodiments, hydraulic energy transfer system 110 may transfer energy (e g., pressure) between two fluids of substantially similar compositions For example, in some conventional systems, a waste stream of the system may include fluid at a high pressure. Hydraulic energy transfer system 110 may accept as high-pressure input (e.g., HP fluid in 130) the high-pressure waste stream and transfer energy from that stream to a low- pressure work stream (e.g., LP fluid in 120). In some systems, such as a closed refrigeration system, energy may be recovered from a high-pressure portion of a fluid stream to reduce pump and / or compressor requirements on the fluid stream.

[0057] In some embodiments, LP in system 122 receives a gas from LP out system 142. In many embodiments, LP in system 122 receives fluid from a receiver (e.g., flash tank). The receiver may receive LP fluid out 140 output from hydraulic energy transfer system 110.

[0058] Fluid handling system 100A further includes a control module. A control module may include one or more controllers. The control module may be configured to perform any of the methods of FIGS. 5A-E. Controllers of the control module may receive data (e.g., measurement data) from sensors associated with fluid handling system 100A. The controllers may be configured to generate control signals based on operations parameters (e.g., threshold values, designated operating ranges, target parameter values, etc.) and / or data received from the sensors. The controllers may include a single device performing one or more control tasks, separate devices for each control task (e g., each controllable component of fluid handling system 100A), several devices for performing a number of functions each, etc. For example, operations of each of the controllers may be performed by a separate device, or operations of all of the controllers may be performed by a single device, or a combination of separate and combined devices may be employed. Components of a control module may include general computing devices, personal computers (PCs), laptops, mobile phones, tablet computers, netbook computers, microcontrollers, purpose-built controllers (e g., hardware, circuitry, etc.), proportional integral derivative (PID) controllers (e.g., three-term controllers), a web appliance, or any other device capable of executing a set of instructions (sequential orotherwise) that specify actions to be taken by that device. A control module may include multiple controllers acting separately (e.g., without input between from one controller to another, without measurement data from one sensor feeding into multiple controllers, etc .). A control module may include multiple controllers working in conjunction with one another, e.g., a target adjustment to operating parameters of the fluid handling system 110A (e.g., as reported by one or more sensor of the system) may include adjustment of operation of one or more components of the system by one or more controllers of the control module.

[0059] Fluid handling system 100A may additionally include one or more sensors to provide sensor data (e g., flowrate data, pressure data, velocity data, etc.) associated with the fluids of fluid handling system 100A. Controllers of fluid handling system 100A may control one or more flow rates of fluid handling system 100A, operation of one or more components of fluid handling system 100A (e.g., operation of motor 160, operation of one or more pumps, etc.), or the like based on the sensor data. In some embodiments, controllers cause one or more flow valves to actuate based on sensor data received.

[0060] The hydraulic energy transfer system 110 may be used in different types of systems, such as fracing systems, desalination systems, refrigeration systems (e.g., FIG. IB), heat pump systems, slurry pumping systems, industrial fluid systems, waste fluid systems, fluid transportation systems, etc.

[0061] Controllers of a control module may provide control signals to interdependent components of fluid handling system 100A. For example, controllers may provide control signals to motor 160 to control an operating speed of hydraulic energy transfer system 110. An operating speed of hydraulic energy transfer system 110 may further affect conditions in other locations of fluid handling system 100A. Other components, for example valves, pumps, etc., may be operated to control conditions of fluid handling system 100A which are affected by the operating speed of hydraulic energy transfer system 110. Controllers may provide signals to various controllable components that are included in fluid handling system 100A. Various components of the subsystems of fluid handling system 100A may be controlled by signals provided by controllers that are based on an operating speed of hydraulic energy transfer system 110.

[0062] FIG. IB illustrates a schematic diagram of a fluid handling system 100B including a hydraulic energy transfer system 110, according to certain embodiments. Fluid handling system 100B may be, for example, a heat transfer system, a refrigeration system, or a heat pump system. Fluid handling system 100B may be configured to cool and / or heat an environment (e.g., an indoor space, a refrigerator, a freezer, etc ). In some embodiments, fluidhandling system 100B includes more components, less components, same routing, different routing, and / or the like than that shown in FIG. IB. Some of the features in FIG. IB that have similar reference numbers as those in FIG. 1 A may have similar properties, functions, and / or structures as those in FIG. 1A.

[0063] In some embodiments, components of fluid handling system 100B may be included to eliminate one or more lift devices to raise pressure in association with one or more of the LP in system 122 or the HP out system 152. HP fluid in 130 may be provided to hydraulic energy transfer system 110 from HP in system 132 (e.g., condenser 138, gas cooler, heat exchanger, etc ). The hydraulic energy transfer system 110 (e g., PX) may exchange pressure between the LP fluid in 120 and HP fluid in 130 to provide HP fluid out 150 to HP out system 152 (e.g., optional high-pressure lift device, high pressure fluid pump, high pressure compressor, etc.) and to provide LP fluid out 140 to LP out system 142 (e.g., evaporator 144, heat exchanger, etc.). In some embodiments, components of fluid handling system 100B may be included such that a high-pressure lift device is eliminated, e.g., a high-pressure lift device is an optional component in some architectures. The LP out system 142 (e g., evaporator 144) may provide the fluid to compressor 178 and optionally a low-pressure lift device. The evaporator 144 may provide the fluid to compressor 178 and / or optionally to a low-pressure lift device. In some embodiments a different component may provide fluid to a low-pressure lift device, evaporator 144, etc. For example, LP fluid out 140 may be provided to a receiver of flash tank. Liquid output from the flash tank may be provided to evaporator 144. In some embodiments, additional valves, lines, pipes, fluid flow paths, etc., may provide fluid to different devices in different orders and / or combinations. The condenser 138 may receive fluid from compressor 178. A controller may control one or more components of fluid handling system 100B, e.g., including motor 160 and various other controllable components.

[0064] The fluid handling system 100B may be a closed system. LP fluid in 120, HP fluid in 130, LP fluid out 140, and HP fluid out 150 may all be a fluid (e.g., refrigerant, the same fluid) that is circulated in the closed system of fluid handling system 100B.

[0065] Fluid handling system 100B may additionally include one or more sensors configured to provide sensor data associated with the system. For example, sensors may report on properties of the fluid at various stages of the system (e.g., various components of the system) such as temperature, pressure, flow rate, density, etc. Sensors may measure properties related to the function of fluid handling system 100B, e.g., a refrigeration system may include one or more temperature sensors reporting on the temperature of the region to be refrigerated. Sensors may measure properties influencing operation of fluid handling system100B, e.g., a heat transfer system intended to heat a region associated with condenser 138 may measure temperature proximate to evaporator 144, and may use the temperature measurements proximate to evaporator 144 to alter one or more operating parameters of fluid handling system 100B, e.g., to achieve a target output (e.g., temperature), to improve efficiency of operation, or the like.

[0066] Protective components 133 may be configured to be incorporated into any of the architectures of FIGS 3A-C or methods of FIGS 5A-B. Controllers of fluid handling system 100B may receive sensor data from sensors (e.g., raw sensor data, preprocessed sensor data, average sensor data, data as a difference of a measured value from a target / threshold value, etc.). Controllers of fluid handling system 100B may be configured to generate one or more control signals based on the input sensor data. Control signals may facilitate operation of adjustable components of fluid handling system 100B.

[0067] Fluid handling system 100B may include one or more valves with variable openings. For example, a fluid flow rate may be altered by adjusting an opening of a valve. Valves may be electronically adjustable, e.g., a valve may be an electronic expansions valve (EEV). A valve may be configured to adjust an opening of the valve (e.g., a percent open value) based on a control signal received from a control module coupled to one or more components of fluid handling system 100B. Fluid handling system 100B may include one or more pumps, compressors, or the like. Pumps and compressors may be configured with variable run speeds (e.g., motor operation speed, pumping speeds, etc.). Pumps and compressors may be configured to adjust a speed of operation based on a control signal received from a control module. Fluid handling system 100B may include motor 160 coupled to a PX of hydraulic energy transfer system 110. Motor 160 may be configured to adjust a speed of operation of the PX based on a signal received from a control module. For example, motor 160 may act as a generator by transferring rotational energy of the PX to electrical energy.

[0068] FIGS. 2A-E are exploded perspective views of a rotary PX 40 (e.g., rotary pressure exchanger, rotary liquid piston compressor (LPC)), according to certain embodiments. Some of the features in one or more of FIGS. 2A-E may have similar properties, functions, and / or structures as those in one or more of FIGS. 1A-B.

[0069] PX 40 is configured to transfer pressure and / or work between a first fluid (e.g., refrigerant, supercritical carbon dioxide, HP fluid in 130) and a second fluid (e.g., refrigerant, superheated gaseous carbon dioxide, LP fluid in 120) with minimal mixing of the fluids. The rotary PX 40 may include a generally cylindrical body portion 42 that includes a sleeve 44(e.g., rotor sleeve) and a rotor 46. The rotary PX 40 may also include two end caps 48 and 50 that include manifolds 52 and 54, respectively. Manifold 52 includes respective inlet port 56 and outlet port 58, while manifold 54 includes respective inlet port 60 and outlet port 62. In operation, these inlet ports 56, 60 enable the first and second fluids to enter the rotary PX 40 to exchange pressure, while the outlet ports 58, 62 enable the first and second fluids to then exit the rotary PX 40. In operation, the inlet port 56 may receive a high-pressure first fluid (e.g., HP fluid in 130) output from a condenser, and after exchanging pressure, the outlet port 58 may be used to route a low-pressure first fluid (e.g., LP fluid out 140) out of the rotary PX 40 to a receiver (e g., flash tank) configured to receive the first fluid from the rotary PX 40. The receiver may form a chamber configured to separate the fluid into a gas and a liquid. Similarly, the inlet port 60 may receive a low-pressure second fluid (e.g., low pressure slurry fluid, LP fluid in 120) from a booster configured to receive a portion of the gas from the receiver and increase pressure of the gas, and the outlet port 62 may be used to route a high- pressure second fluid (e.g., high pressure slurry fluid, HP fluid out 150) out of the rotary PX 40. The end caps 48 and 50 include respective end covers 64 and 66 (e.g., end plates) disposed within respective manifolds 52 and 54 that enable fluid sealing contact with the rotor 46.

[0070] Ports of the PX are fluidly coupled to a fluid system. The fluid system includes fluid handling architecture 92. Fluid handling architecture 92 includes a number of components for performing operations, adjusting fluid conditions, providing system control, etc., such as the components described in connection with FIGS. 1 A-B. Fluid handling architecture 92 may include protective and control components 182, e.g., one or more components that enable removal from or bypass of one or more pumps or compressors of fluid handling architecture 92. For example, components such as heat exchangers and / or receivers may enable elimination of one or more booster pumps, compared to other PX fluid systems. More discussion of architectures including one or more protective or other controllable components may be found in connection with FIGS 3A-C and FIGS. 4A-B.

[0071] One or more components of the PX 40, such as the rotor 46, the end cover 64, and / or the end cover 66, may be constructed from a wear-resistant material (e.g., carbide, cemented carbide, silicon carbide, tungsten carbide, etc.) with a hardness greater than a predetermined threshold (e.g., a Vickers hardness number that is at least 1000, 1250, 1500, 1750, 2000, 2250, or more). For example, tungsten carbide may be more durable and may provide improved wear resistance to abrasive fluids as compared to other materials, such as alumina ceramics. Additionally, in some embodiments, one or more components of the PX40, such as the rotor 46, the end cover 64, the end cover 66, and / or other sealing surfaces of the PX 40, may include an insert. In some embodiments, the inserts may be constructed from one or more wear-resistant materials (e.g., carbide, cemented carbide, silicon carbide, tungsten carbide, etc.) with a hardness greater than a predetermined threshold (e.g., a Vickers hardness number that is at least 1000, 1250, 1500, 1750, 2000, 2250, or more) to provide improved wear resistance.

[0072] The rotor 46 may be cylindrical and disposed in the sleeve 44, which enables the rotor 46 to rotate about the axis 68. The rotor 46 may have a plurality of channels 70 (e.g., ducts, rotor ducts) extending substantially longitudinally through the rotor 46 with openings 72 and 74 (e.g., rotor ports) at each end arranged symmetrically about the longitudinal axis 68. The openings 72 and 74 of the rotor 46 are arranged for hydraulic communication with inlet and outlet apertures 76 and 78 (e.g., end cover inlet port and end cover outlet port) and 80 and 82 (e.g., end cover inlet port and end cover outlet port) in the end covers 64 and 66, in such a manner that during rotation the channels 70 are exposed to fluid at high-pressure and fluid at low-pressure. As illustrated, the inlet and outlet apertures 76 and 78 and 80 and 82 may be designed in the form of arcs or segments of a circle (e.g., C-shaped).

[0073] An operating speed of PX 40 may be utilized to control the extent of mixing between the first and second fluids in the rotary PX 40, which may be used to improve the operability of the fluid handling system (e.g., fluid handling systems 100A-B of FIGS. 1A- B). For example, varying the volumetric flow rates of the first and / or second fluids entering the rotary PX 40 allows the operator (e.g., system operator, plant operator) to control the amount of fluid mixing within the PX 40. In addition, varying the rotational speed of the rotor 46 (e.g., via a motor) also allows the operator to control mixing. Three characteristics of the rotary PX 40 that affect mixing are: (1) the aspect ratio of the rotor channels 70; (2) the duration of exposure between the first and second fluids; and (3) the creation of a barrier (e.g., fluid barrier, piston, interface) between the first and second fluids within the rotor channels 70. First, the rotor channels 70 (e.g., ducts) are generally long and narrow, which stabilizes the flow within the rotary PX 40. In addition, the first and second fluids may move through the channels 70 in a plug flow regime with minimal axial mixing. Second, in certain embodiments, the speed of the rotor 46 reduces contact between the first and second fluids. For example, the speed of the rotor 46 (e.g., rotor speed of approximately 1200 revolutions per minute (RPM)) may reduce contact times between the first and second fluids to less than approximately 0.15 seconds, 0.10 seconds, or 0.05 seconds. Third, the rotor channel 70 (e.g., a small portion of the rotor channel 70) is used for the exchange of pressure between the firstand second fluids. In some embodiments, a volume of fluid remains in the channel 70 as a barrier between the first and second fluids. All these mechanisms may limit mixing within the rotary PX 40. Moreover, in some embodiments, the rotary PX 40 may be designed to operate with internal pistons or other barriers, either complete or partial, that isolate the first and second fluids while enabling pressure transfer.

[0074] In some embodiments, a speed of operation of the PX may be set (e g., targeting the properties listed above, or other properties of interest in the fluid system). Properties of the fluid system may be affected by the PX 40 rotational speed. A control module may receive an indication of PX 40 speed of operation (e.g., from a sensor, from a control signal for a controller of PX 40, etc.), and may generate control signals for controllable components of fluid handling architecture 92 which are based on speed of operation of PX 40.

[0075] FIGS. 2B-2E are exploded views of an embodiment of the rotary PX 40 illustrating the sequence of positions of a single rotor channel 70 in the rotor 46 as the channel 70 rotates through a complete cycle. It is noted that FIGS. 2B-2E are simplifications of the rotary PX 40 showing one rotor channel 70, and the channel 70 is shown as having a circular cross- sectional shape. In other embodiments, the rotary PX 40 may include a plurality of channels 70 with the same or different cross-sectional shapes (e.g., circular, oval, square, rectangular, polygonal, etc.). Thus, FIGS. 2B-2E are simplifications for purposes of illustration, and other embodiments of the rotary PX 40 may have configurations different from those shown in FIGS. 2A-2E. As described in detail below, the rotary PX 40 facilitates pressure exchange between first and second fluids (e.g., a particulate-free fluid and a slurry fluid, higher pressure refrigerant and lower pressure refrigerant, etc.) by enabling the first and second fluids to briefly contact each other within the rotor 46. In some embodiments, the PX facilitates pressure exchange between first and second fluids by enabling the first and second fluids to contact opposing sides of a barrier (e.g., a reciprocating barrier, a piston, not shown). In some embodiments, this exchange happens at speeds that result in limited mixing of the first and second fluids. The speed of the pressure wave traveling through the rotor channel 70 (as soon as the channel is exposed to the aperture 76), the diffusion speeds of the fluids, and / or the rotational speed of rotor 46 may dictate whether any mixing occurs and to what extent.

[0076] FIGS. 2B-E include protective and control components 182, as part of a fluid system fluidly coupled to one or more outlets of PX 40. Protective and control components 182 may enable removal of one or more pumps or compressors (e.g., a low-pressure boosterand / or high-pressure booster) from a fluid handling system, as described in connection with FIG. 1A.

[0077] Controllable components of a fluid handling system coupled to the PX depicted in FIGS. 2B-E may be provided control signals in accordance with any of the methods of FIGS. 5A-B. FIGS. 2B-E depict various stages of operation of PX 40. Operation of PX 40 may be controlled by a control module. For example, the control module may be operatively coupled to a motor of the PX. The control module may send one or more control signals to the motor. The motor may adjust operation of PX 40, e.g., may adjust a speed of rotation of PX 40, a speed of rotation of PX 40, etc. The control module may be operatively coupled to other components of a fluid handling system that affect operation of PX 40. For example, one or more compressors that supply fluid to PX 40 may be controlled by the control module, one or more valves that supply fluid to PX 40 may be controlled by the control module, one or more valves coupled to an outlet of PX 40 may be controlled by the control module, etc. These components may include controllable components described in connection with architectures of FIGS. 3A-C. These controllable components may be associated with control via methods described in connection with FIGS. 5A-B.

[0078] FIG. 2B is an exploded perspective view of an embodiment of a rotary PX 40 (e.g., rotary LPC), according to certain embodiments. In FIG. 2B, the channel opening 72 is in a first position. In the first position, the channel opening 72 is in fluid communication with the aperture 78 in end cover 64 and therefore with the manifold 52, while the opposing channel opening 74 is in hydraulic communication with the aperture 82 in end cover 66 and by extension with the manifold 54. The rotor 46 may rotate in the clockwise direction indicated by arrow 84. In operation, low-pressure second fluid 86 (e.g., low pressure slurry fluid) passes through end cover 66 and enters the channel 70, where it contacts the first fluid 88 at a dynamic fluid interface 90. The second fluid 86 then drives the first fluid 88 out of the channel 70, through end cover 64, and out of the rotary PX 40. However, because of the short duration of contact, there is minimal mixing between the second fluid 86 (e.g., slurry fluid) and the first fluid 88 (e.g., particulate-free fluid). In some embodiments, low pressure second fluid 86 contacts a first side of a barrier (e.g., a piston, not shown) disposed in channel 70 that is in contact (e.g., on an opposing side of the barrier) by first fluid 88. The second fluid 86 drives the barrier which pushes first fluid 88 out of the channel 70. In such embodiments, there is negligible mixing between the second fluid 86 and the first fluid 88.

[0079] FIG. 2C is an exploded perspective view of an embodiment of a rotary PX 40 (e.g., rotary LPC), according to certain embodiments. In FIG. 2C, the channel 70 has rotatedclockwise through an arc of approximately 90 degrees. In this position, the opening 74 (e.g., outlet) is no longer in fluid communication with the apertures 80 and 82 of end cover 66, and the opening 72 is no longer in fluid communication with the apertures 76 and 78 of end cover 64. Accordingly, the low-pressure second fluid 86 is temporarily contained within the channel 70.

[0080] FIG. 2D is an exploded perspective view of an embodiment of a rotary PX 40 (e g., rotary LPC), according to certain embodiments. In FIG. 2D, the channel 70 has rotated through approximately 60 degrees of arc from the position shown in FIG. 2B. The opening 74 is now in fluid communication with aperture 80 in end cover 66, and the opening 72 of the channel 70 is now in fluid communication with aperture 76 of the end cover 64. In this position, high-pressure first fluid 88 enters and pressurizes the low-pressure second fluid 86, driving the second fluid 86 out of the rotor channel 70 and through the aperture 80.

[0081] FIG. 2E is an exploded perspective view of an embodiment of a rotary PX 40 (e.g., rotary LPC), according to certain embodiments. In FIG. 2E, the channel 70 has rotated through approximately 270 degrees of arc from the position shown in FIG. 2B. In this position, the opening 74 is no longer in fluid communication with the apertures 80 and 82 of end cover 66, and the opening 72 is no longer in fluid communication with the apertures 76 and 78 of end cover 64. Accordingly, the first fluid 88 is no longer pressurized and is temporarily contained within the channel 70 until the rotor 46 rotates another 90 degrees, starting the cycle over again.

[0082] FIGS. 3A-C and FIGS. 4A-B are schematic diagrams of fluid handling systems 300A-C and 400A-B including PXs, according to certain embodiments. Some of the features in one or more of FIGS. 3A-C may have similar properties, functions, and / or structures as those in one or more of FIGS. 1A-B and / or one or more of FIGS. 2A-E (e.g., features that have similar names and / or reference numbers). Systems of one or more of FIGS. 3A-C may be used to perform the methods of one or more of FIGS. 5A-B. Some of the features in one or more of FIGS. 3A-C may have similar features, properties, functions, and / or structures as those in one or more of FIGS. 4A-B. Systems of one or more of FIGS. 4A-B may be used to perform the methods of one or more of FIGS. 5A-B.

[0083] FIGS. 3A-C and 4A-B depict various fluid handling system architectures (fluid handling systems 300A-C and 400A-B) and various controllers, according to certain embodiments. The depicted architectures are example architectures, e.g., depicted architectures highlight operations of controllers of the fluid handling systems. Any of the controllers depicted in FIGS. 4A-B may be included in any combination in any architecturedesign of a fluid handling system. For example, a controller performing operations such as controller 490 of FIG. 4A may be included in another architecture that does not depict the controller (e.g., fluid handling system 300C of FIG. 3C), a controller performing operations such as controller 492 controlling a valve of FIG. 4B may be included in an architecture similar to that depicted in FIG. 3A, etc. A fluid handling system including any controller depicted herein (e.g., any controller adjusting operation of a component of a fluid handling and / or energy transfer system including a PX based on sensor data from the system), alone or in any combination, is within the scope of this disclosure. Controllers may be isolated components (e g , each controller may be a separate device), controllers may be combined components (e.g., operations of two or more controllers may be performed by the same device, control system), etc. Controllers may provide control signals in response to various inputs, e g., sensor data provided to the controllers. Controllers may provide control signals to adjust properties of the fluid handling systems, e.g., to adjust values of one or more conditions of the fluid handling systems such that the condition values satisfy one or more threshold conditions.

[0084] In some embodiments, devices of fluid handling systems 300A-C and 400 A-B of FIGS. 3A-C and 4A-B may communicate via wired connections. In some embodiments, devices of these fluid handling systems may communicate wirelessly. In some embodiments, devices depicted in FIGS. 4A-B may communicate via a network. For example, controllers of FIGS. 4A-B may receive sensor data via a network and may transmit control signals via the network. In some embodiments, devices of fluid handling systems 400 A-B of FIGS. 4A-B may communicate via one or more wired networks. In some embodiments, devices of fluid handling systems 400A-B of FIGS. 4A-B may communicate via one or more wireless networks (e.g., personal area networks, wireless local area networks, etc.). In some embodiments, devices of fluid handling systems 400A-B may communicate via some wired and some wireless networks.

[0085] In some embodiments, controllers of fluid handling systems 400A-B may be PID controllers. Controllers of fluid handling systems 400A-B may calculate an error value (e.g., the difference between a target set point and a measured value). Controllers of fluid handling systems 400A-B may apply a correction (e.g., generate a control signal) based on proportional, integral, and derivative terms of the error value. For example, the proportional term may be based on the difference between the set point value and the measured value, the integral term may be based on past values of the error term integrated over time, and the derivative term may be based on a predicted future trend of the error term based on thecurrent rate of change of the error term. In some embodiments, controllers of fluid handling systems 400A-B may be computing devices. Controllers of fluid handling systems 400A-B may be implemented as software (e g , executed by a general -purpose computing device), hardware, or a combination of hardware and software. In some embodiments, operation of controllers of fluid handling systems 400A-B may include receiving one or more adjustable settings, parameters, etc. For example, the response (e.g., magnitude of output signal, value of an adjustment instruction included in a control signal, etc.) of a controller may be of variable strength (e.g., for a given difference between a measured value and a target value of a measured property, a controller may have a range of possible output values, and implementation of one of the range of outputs may be responsive to one or more settings and / or parameters of the controller). In some embodiments, a controller may have an associated lookup table, and for a given input (e.g., a difference between a set point and a measured value), the controller may produce an output in accordance with the table. In some embodiments, a controller may perform a calculation including an adjustable parameter (e.g., a user-adjustable parameter, and adjustable setting, etc.), and in response to an input, the controller may generate an output based on the input. In some embodiments, parameters and / or settings of controllers may be selected / adjusted by a user. In some embodiments, parameters and / or settings of a controller may be adjusted by a computer-implemented method, e.g., of the controller, of an associated computing device, or the like.

[0086] In some embodiments, performance of a controller may be tracked (e.g., measured and stored for analysis over time). If a controller causes overshoot (e.g., if a component of a fluid handling system over-corrects responsive to receiving a control signal from the controller, if the measured property value passes through a target value before settling within a threshold of the target value, etc.) above a threshold value (e.g., a percent of the difference between the initial value and the target value, above a threshold value of frequency and / or severity of overshoot, etc.), sensitivity of the controller (e.g., strength of response to a measurement different from a target property value) may be decreased. For example, a controller may generate a control signal responsive to receiving a measurement different from a set point (e.g., a difference between a set point and a measured value exceeding a threshold). The controller may later receive a measurement different from the set point but in the opposite direction (e.g., the control signal may have intended to correct a measured value lower than a set point, and the subsequent measurement may be higher than the set point). Responsiveness of the controller (e.g., a parameter of a calculation that determines the strength of an output relative to an input difference between a set point and a measured value,a table entry determining the severity of action instructed in a control signal based on an input from a sensor, etc.) may be adjusted to reduce the likelihood of an overshoot in future operations. Adjustment to a controller setting may be global, e.g., a parameter or table may be updated such that all future control signals are generated according to the update. Adjustment to a controller setting may not apply globally, e.g., one or more lookup table values may be adjusted while others are left unadjusted (e g., a lookup table value associated with a range of differences between a set point and a measured value may be adjusted, a lookup table value associated with one or more differences for a range of measured values may be adjusted, etc ), a parameter for use in some situations may be updated (e g., a list of parameters may be applied for different measured values, different set point values, different values of a difference between a measured value and a set point, etc.), or the like.

[0087] Similarly, if a controller is not sensitive enough (e.g., if property values in the system are slower than desired to reach values within a threshold value of a target value), response of the controller may be increased. For example, a controller may receive a measurement different than a set point (e.g., a controller may be configured to receive pressure measurements from a pressure gauge and may receive a measurement that is different from a set point pressure value by at least a threshold amount). The controller may generate a control signal responsive to receiving the measurement (e.g., the controller may generate a control signal for a valve to open to adjust pressure at the pressure gauge). The controller may subsequently receive a measurement that the pressure has not reached the set point (e.g., the action taken by the valve responsive to the control signal was not sufficient to reduce the difference between the set point and the measured value below a threshold). One or more settings / parameters of the controller may be adjusted to increase the response of the controller (e.g., increase the output signal generated based on an input signal of a given strength, increase the severity of instructions included in a control signal associated with a given difference between a set point and a measured value, etc.) to an input.

[0088] In some embodiments, determining an update to the sensitivity and / or response (e.g., an update to a parameter or setting dictating the strength or severity of an output) of a controller may be performed by a machine learning model. A machine learning model may be trained with input including a target property value, a measured property value, a response of the controller (e.g., a control signal), and / or a result of a component of the system acting on an instruction received by the controller. The machine learning model, once trained, may be configured to receive as input a measured property value and a target value and generate as output an indication of an appropriate action (e.g., a control signal) to be taken by one ormore components of the fluid handling system. For example, a machine learning model may be provided with historical data as training data. The machine learning model may be provided with one or more historical property values associated with a property to be corrected in a fluid handling system (e.g., one or more set point values and one or more measured values generated before and after a component of the system performs an action as instructed by a controller) as training input. The machine learning model may further be provided with historical property values after an adjustment to correct the measured property values is made (e.g., one or more measured values, measured after a control signal was generated for one or more components of the system). The machine learning model may be provided with one or more historical control signals (or data indicative of the control signals) as target output. Once trained, the machine learning model may receive as input current property values (e.g., one or more set point values, one or more measured values, etc.) and generate as output a control signal (or data associated with a control signal) that is predicted to bring the one or more measured property values within a threshold difference value of the one or more set point values.

[0089] Fluid handling systems 300A-C and 400A-B may be heat transfer systems. Fluid handling systems 300A-C and 400A-B may be refrigeration systems. Fluid handling systems 300A-C and 400A-B may be heat pump systems. Fluid handling systems 300A-C and 400A- B may be reversible heat pump systems. A reversible heat pump system may include components not pictured in FIGS. 3A-C, for example, a reversing valve (e.g., a 4-way valve to reverse flow). A reversible heat pump system may reverse direction of flow of a coolant fluid in one or more portions of the fluid handling system, e.g., flow through a condenser and / or an evaporator (e.g., outdoor heat exchanging unit and / or indoor heat exchanging unit) may be reversed. A reversible heat pump system may not reverse direction of flow in one or more portions of the fluid handling system, e.g., flow through a compressor or pump may not be reversed. A reversible heat pump system may include additional flow paths, additional valves, etc., utilized for example when flow is reversed. Though additional components and flow paths associated with a reversible heat pump system are not depicted in FIGS. 3A-C, reversible heat pump systems including such components are within the scope of this disclosure.

[0090] FIG. 3A is a schematic diagram of a fluid handling system 300A including a PX 310 and heat exchangers for exchanging heat between streams of working fluid, subcooler 315 and superheater 311 , according to some embodiments. Fluid handling system 300A may be configured to control various components of the system based on sensor data receivedfrom sensors of the system. Fluid handling system 300A may be configured to determine an opening of one or more valves based at least in part on a speed of operation of PX 310. Fluid handling system 300A may be configured to determine an opening of one or more valves based on measured conditions of fluid handling system 300A. Controls of architectures in connection with this disclosure are discussed in more detail in connection with FIGS. 4A-B.

[0091] PX 310 may be a rotary pressure exchanger. In some embodiments, PX 310 is an isobaric or substantially isobaric pressure exchanger. PX 310 may be configured to exchange pressure between a first fluid and a second fluid. PX 310 may be configured to exchange pressure between a high pressure first fluid (e.g., provided to the PX 310 at a high-pressure inlet, labeled HP-IN) and a low pressure second fluid (e.g., provided to the PX 310 at a low- pressure inlet, LP-IN). PX 310 may decrease the pressure of the first fluid (e.g., for output from PX 310 at a low-pressure outlet, LP-OUT) and increase the pressure of the second fluid (e.g., for output from PX 310 at a high-pressure outlet, HP-OUT). In some embodiments, PX 310 is coupled to a motor (e.g., rotation of a rotor of PX 310 is controlled and / or adjusted by motor. In some embodiments, mass flow (e.g., of the first fluid, of the second fluid, etc.) through PX 310 may be related to a speed of operation of PX 310 (e.g., a speed of rotation of a rotor of a rotary PX). In some embodiments, pressure of fluid (e.g., the first fluid, the second fluid, etc.) in various components of a fluid handling system (e.g., fluid handling systems 300A-C) may be related to a speed of operation of PX 310.

[0092] In some embodiments, PX 310 is configured to receive the first fluid at a high pressure (e.g., HP fluid in 130 of FIGS. 1A-B) via a high-pressure inlet. In some embodiments, PX 310 is configured to receive the second fluid at a low pressure (e.g., LP fluid in 120 of FIGS. 1A-B) via a low-pressure inlet. Although there is a reference to “high pressure” and “low pressure,” “high pressure” and “low pressure” may be relative to one another and may not connote certain pressure values (e.g., the pressure of the HP fluid in 130 is higher than the pressure of LP fluid in 120). PX 310 may exchange pressure between the first fluid and the second fluid. PX 310 may provide the first fluid via a low-pressure outlet (e.g., LP fluid out 140) and may provide the second fluid via a high-pressure outlet (e.g., HP fluid out 150). In some embodiments, the first fluid provided via the low-pressure outlet is at a low pressure and the second fluid provided via the high-pressure outlet is at a high pressure. PX 310 may act as a high-pressure expansion valve, e.g., fluid that flows through PX 310 (e.g., from a high-pressure inlet to a low-pressure outlet) may expand. PX 310 may transfer pressure from one fluid stream to another, increasing the pressure of one fluid stream. PX 310 may act as both an isentropic (or substantially isentropic) expansion device and a compressor,which may cause transfer of heat, may facilitate one or more operations of a refrigeration cycle, or the like. The compression process of PX 310 may be substantially isenthalpic.

[0093] In some embodiments, the first fluid may be a refrigerant fluid in a supercritical state (e.g., supercritical CO2). In some embodiments, the first fluid may be a refrigerant fluid in a liquid state (e.g., liquid CO2). In some embodiments, the second fluid may be a refrigerant fluid in a gaseous state (e g., gaseous CO2). In some embodiments, the second fluid may be a refrigerant fluid in a two-phase mixture (e.g., a liquid-gas mixture of CO2). In some embodiments, the second fluid may be a refrigerant fluid in a liquid state (e.g., liquid CO2)

[0094] In some embodiments, fluid handling system 300A includes a main gas cooler 329 (e.g., a condenser), an evaporator 318, and a main compressor 322. In some embodiments, fluid handling system 300A may include an auxiliary gas cooler, e.g., coupled between HP- OUT and receiver 313. In some embodiments, main gas cooler 329 and / or an auxiliary gas cooler may or may not act as condensers, e.g., the fluid handling system may be operated at pressures and temperatures such that fluid does or does not condense in the gas coolers. Any embodiment discussed herein may include a gas cooler that may or may not act as a condenser in one or more applications. In some embodiments, e.g., above the critical point of a fluid, the thermodynamic distinction between gas and liquid of a fluid disappears, and fluid (e.g., fluid in a condenser) may exist in a super critical state (e.g., both input and output fluid of a condenser may be in a supercritical state, one of input or output fluid of a condenser may be in a supercritical state, neither fluids may be in a supercritical state, etc.). In some embodiments, fluid handling system 300A is a refrigeration system. For example, evaporator 318 and / or second evaporator 319 may facilitate absorption of heat by fluid handling system 300A from a heat source (e.g., a refrigerated area, a cold reservoir, etc.) to a refrigeration fluid. The heat may be rejected to a heat sink (e.g., the environment, a hot reservoir, etc.) via the main gas cooler 329 and / or auxiliary gas cooler. In some embodiments, the refrigeration fluid facilitates heat transfer from an environment associated with the evaporator 318 to an environment associated with the main gas cooler 329. Main compressor 322 of fluid handling system 300A may increase corresponding pressure of the refrigeration fluid along a flow path between the evaporator 318 and the main gas cooler 329. In some embodiments, the refrigeration fluid is CO2 or another refrigeration fluid. The refrigeration fluid may flow substantially in a cycle (e g., from main gas cooler 329 to PX 310 to evaporator 318 to main compressor 322 to main gas cooler 329, etc.).

[0095] In some embodiments, fluid handling system 300A is a heat pump system. For example, heat may be rejected by fluid at main gas cooler 329 into a target region to be heated (e g., for heating the interior space of a building). Heat may be absorbed from the environment by the fluid of fluid handling system 300A at evaporator 318 for transfer to the environment of main gas cooler 329. In some embodiments, fluid handling system 300A may be a reversible heat pump.

[0096] In some embodiments, main compressor 322 increases pressure of fluid more than a threshold amount (e.g., main compressor 322 may operate over a pressure differential that is greater than a threshold amount, or the like). For example, main compressor 322 may increase pressure of the fluid by approximately 100-1200 psi, by approximately 500-1100 psi, by approximately 800-1000 psi, by approximately 900 psi, by at least 100 psi, by at least 500 psi, any included range, or the like. In some embodiments, operations of main compressor 322 may be performed by more than one physical device, e g., multiple compressors, multiple pumps, or the like. Multiple compressors performing operations of main compressor 322 may be arranged in parallel, in series, or a combination of arrangements. Any discussion of main compressor 322 may be generalized to include multiple devices, e.g., by summing energy consumed or calculating total fluid flow through the compressor system taking into account arrangement, specifications, and operating speeds of each compressor of the compressor system.

[0097] A motor or other speed adjusting device may be configured to adjust operation of PX 310 (e.g., by adjusting a speed of operation of the motor). Adjusting speed of operation of PX 310 may be performed responsive to receiving a control signal from a controller. Control of PX 310 may be based on pressure of fluid of the main gas cooler 329. Control of PX 310 may further be based on additional metrics, such as ambient temperature, fluid temperature, target evaporator temperature, efficiency of operation of fluid handling system 300A, etc. A controller may generate a control signal directed at achieving and / or maintaining a target pressure of main gas cooler 329. The target pressure of main gas cooler 329 may be modified by ambient temperature (e.g., heat sink temperature for rejected heat), for example to achieve optimal energy efficiency, heat transfer, refrigeration, or the like. For example, increasing a speed of operation of PX 310 may increase a flow rate of fluid through PX 310. Increasing a speed of operation of PX 310 may decrease fluid pressure of main gas cooler 329.

[0098] In some embodiments, a target pressure of main gas cooler 329 may be chosen to maximize heat transfer of the system, maximize heat transfer between main gas cooler 329 and the environment, maximize energy efficiency of the system, maximize a coefficient ofperformance (COP, e.g., a ratio between heat transferred by the system and power expended by pumps / compressors of the system), or the like.

[0099] In some embodiments, a device for adjusting PX speed may act to operate, actuate, or accelerate PX 310. For example, a motor may drive PX 310. A motor may draw power from a power source to drive PX 310. In some embodiments, a motor may act like a generator. For example, PX 310 may be driven by fluid of fluid handling system 300A (e g., driven by a pressure differential in the fluid, driven by one or more pumps and / or compressors of the system, etc.). A motor may impart additional resistance to operation of PX 310 (e g., resistance to rotation of a rotor of a rotary PX), which may cause a speed of operation of PX 310 to decrease. A motor may generate electrical power (e g., may convert rotational energy of PX 310 into electrical energy).

[0100] In some embodiments, evaporator 318 (and / or second evaporator 319) is a heat exchanger to provide corresponding thermal energy from an environment (e g., a medium of an environment) to a fluid of fluid handling system 300A. For example, evaporator 318 may receive heat (e g., thermal energy) from air of the environment and provide the heat to the fluid. In some embodiments, the environment is a refrigerated space such as the inside of a refrigerator or freezer, an interior space (e.g., of a building or vehicle), or any other space that is to be kept cool. For example, the environment can be the interior of a freezer or refrigeration section at a supermarket or warehouse. In some embodiments, evaporator 318 may absorb heat from the environment to be provided to main gas cooler 329, e.g., heating the region around main gas cooler 329 may be a target outcome of fluid handling system 300A. In some embodiments, evaporator 318 and second evaporator 319 may be associated with different target uses, different environments, different target temperatures, or the like. For example, evaporator 318 may be associated with one or more refrigerated sections of a supermarket, while second evaporator 319 may be associated with one or more freezers of the supermarket.

[0101] In some embodiments, fluid handling system 300A may include a secondary evaporator. Fluid handling system 300A may further include secondary components corresponding to any components of evaporator 318, e.g., input and output lines, valves, gauges, controllers, etc. In some embodiments, the second evaporator 319 receives a portion of flow of fluid directed to evaporator 318. For example, the secondary evaporator may receive a portion of the flow from the low-pressure outlet of PX 310, e.g., via receiver 313. In some embodiments, a secondary evaporator may target a different temperature than evaporator 318 (e.g., the evaporators may be associated with refrigeration systems withdifferent target temperatures, such as a refrigerator and freezer). In some embodiments, the two evaporators (e.g., evaporator 318 and the secondary evaporator) may be operated at different fluid pressures. Fluid output by one or more of the secondary evaporators may be directed to one or more components (e.g., valves, expansions valves, pumps, compressors, or the like, such as low-temperature compressor 323) to alter the pressure of the output fluid such that the pressures are substantially similar when the output streams of the two evaporators are combined.

[0102] In some embodiments, main gas cooler 329 and / or an auxiliary gas cooler is a heat exchanger to provide thermal energy from the fluid of fluid handling system 300A to another environment. For example, main gas cooler 329 may reject heat (e.g., thermal energy) to air of an outside (e g., exterior) environment. In some embodiments, main gas cooler 329 exchanges thermal energy (e.g., rejects heat) to an outside space. For example, main gas cooler 329 may be placed outside a supermarket or warehouse building (e.g., on a roof of the building) and reject heat to the outside environment. In another example, main gas cooler 329 may be placed in the ground and facilitate the transfer of thermal energy between the fluid and the ground. In some embodiments, main gas cooler 329 rejects heat to an interior space while evaporator 318 absorbs heat from an exterior space (e.g., as in a heat pump configuration that is providing heating to the interior space). Thermal energy rejected from main gas cooler 329 may be used to heat an enclosed (e.g., substantially enclosed) space.

[0103] In some embodiments, fluid handling system 300A may include an auxiliary gas cooler. In some embodiments, the auxiliary gas cooler receives the second fluid from the high-pressure outlet of PX 310, and main gas cooler 329 receives output from main compressor 322. In some embodiments, the auxiliary gas cooler is a heat exchanger that exchanges thermal energy (e.g., heat) between the second fluid and a medium of an environment. In some embodiments, the auxiliary gas cooler exchanges thermal energy between the second fluid and the same environment with which the main gas cooler 329 exchanges thermal energy, such as an exterior space of a building. In other embodiments, the auxiliary condenser exchanges thermal energy between the second fluid and a different environment with which the main gas cooler 329 exchanges thermal energy. In some embodiments, the auxiliary gas cooler operates at a temperature different than main gas cooler 329. In some embodiments, auxiliary gas cooler may operate at a different pressure than main gas cooler 329. For example, auxiliary gas cooler may operate at a lower pressure than main gas cooler 329. An auxiliary gas cooler may operate at a target pressure different than a target pressure of main gas cooler 329, at a target pressure differential compared tomain gas cooler 329, or the like. An auxiliary gas cooler may be operated around 20 psi lower in pressure than main gas cooler 329. An auxiliary gas cooler may be operated 15-30 psi below pressure of main gas cooler 329. In some embodiments, the main gas cooler and the auxiliary gas cooler may be provided by the same device, e.g., a gas cooler with multiple fluid channels to accommodate multiple fluid flows. In some embodiments, the main gas cooler and / or the auxiliary gas cooler may be associated with devices for adjusting heat exchanged with the fluid in the gas cooler. For example, main gas cooler 329 and / or auxiliary gas cooler may include or be associated with fans for increasing airflow proximate the gas coolers, for increasing heat transfer from the gas coolers, etc.

[0104] Fluid handling system 300A further includes flash gas valve 320. Fluid handling system 300A may include a flash gas valve 320 to regulate a flow of gas on a flash gas bypass flow path. In some embodiments, flash gas valve 320 is a bypass valve that regulates a flow of gas from a gas outlet of the receiver 313 (e.g., flash tank) to be combined with output of the evaporator 318. In some embodiments, the flow of gas from the receiver 313 flows along the flash gas bypass flow path to bypass the evaporator 318. In some embodiments, the flash gas flow path is between receiver 313 and a location downstream of an outlet of the evaporator 318. The gas flowing along the flash gas bypass flow path may be combined with output of the evaporator 318. The flash gas valve 320 may cause gas collected in the receiver 313 to expand (e.g., decrease in pressure) as the gas flows toward the main compressor 322. The flash gas valve 320 may, in some embodiments, be an adjustable valve. In some embodiments, the flash gas valve 320 is caused to actuate by a controller based on sensor data.

[0105] Fluid handling system 300A may include an expansion valve 316 associated with evaporator 318, and a secondary expansion valve 317 associated with second evaporator 319. In some embodiments, expansion valve 316 is disposed along a flow path between receiver 313 and evaporator 318, e.g., coupled between receiver 313 and evaporator 318. Expansion valve 316 may be an adjustable valve (e.g., an electronic expansion valve, a thermostatic expansions valve, a ball valve, a gate valve, a poppet valve, etc ). Expansion valve 316 may be controllable by a user (e.g., a technician, an operator, an engineer, etc.) or by a controller. In some embodiments, the expansion valve 316 is caused to actuate by a controller based on sensor data (e.g., pressure sensor data, flowrate sensor data, temperature sensor data, etc.). In some embodiments, expansion valve 316 is a thermal expansion valve. Expansion valve 316 may actuate (e.g., open and / or close) based on temperature data associated with the evaporator 318 (e.g., temperature of liquid in the evaporator, temperature of gas in theevaporator, temperature of fluid entering the evaporator, temperature of fluid exiting the evaporator, etc.). For example, a pressure-sensitive component (e.g., sensing bulb) of the expansion valve 316 may increase or decrease pressure on a diaphragm of the expansion valve 316, causing a poppet valve coupled to the diaphragm to open or close, thus causing more or less flow of fluid to the evaporator 318, causing more or less expansion of the fluid. The pressure-sensitive component of the expansion valve may be positioned proximate to the downstream end of the evaporator 318 (e.g., proximate the outlet of the evaporator 318, outside evaporator 318, inside evaporator 318, or the like) and may be fluidly coupled to the diaphragm via a fluid line (e g., a sensing capillary). In some embodiments, expansion valve 316 is controlled and actuated entirely based on electronic commands (e.g., from a controller). Secondary expansion valve 317 may share one or more features with expansion valve 316, including sharing features of the relationship between expansion valve 316 and evaporator 318 with second evaporator 319.

[0106] Fluid handling system 300A includes subcooler 315. Subcooler 315 may be a heat exchanger, configured to exchange heat between portions of fluid output by main gas cooler 329. Subcooler 315 may include a main or primary fluid channel, coupled to a main cooling flow of working fluid. Subcooler 315 may include a secondary or cooling fluid channel, coupled to a fluid stream to absorb heat from the main flow in subcooler 315. Subcooling valve 312 may be a control valve, e.g., may be opened to a target opening to allow a target flow through the secondary channel of subcooler 315. Subcooling valve 312 may act as an expansion valve, e.g., temperature of fluid provided to subcooling valve 312 may be higher than temperature of fluid provided by subcooling valve 312 to secondary channel of subcooler 315. PX 310 may enable this additional cooling step without loss of efficiency due to additional pumping power required to increase pressure of the secondary cooling fluid, by providing compression of the fluid by exchanging pressure with fluid from the main channel of subcooler 315. Main fluid may be provided by subcooler 315 to a high-pressure inlet of PX 310. Secondary cooling fluid may be provided by subcooler 315 to a low-pressure inlet of PX 310.

[0107] Fluid handling system 300A further includes superheater 311. Superheater 311 may be a heat exchanger, configured to exchange heat between fluid in a primary channel (e.g., fluid exiting HP-OUT) and fluid in a secondary channel (e.g., fluid that has passed through an evaporator, but has not yet passed through main compressor 322). Fluid exiting HP-OUT may be high-pressure, high-temperature fluid. Heat may be exchanged which decreases the temperature of the fluid provided by HP-OUT and increases the temperature of the fluidprovided to main compressor 322 (or low-temperature compressor 323, in some embodiments). Superheater 311 may provide multiple advantages to fluid handling system 300A Superheater 311 may provide an increase to temperature of working fluid provided to main compressor 322. In some cases, a compressor such as compressor 322 may be configured to obtain fluid of a single phase, e.g., to receive only gas. If a different phase (e.g., liquid) is provided to compressor 322, it may cause damage to compressor 322, as well as other inefficiencies in fluid handling system 300A. Increasing a temperature of fluid provided to main compressor 322 may reduce a risk of providing liquid to main compressor 322, protecting components of fluid handling system 300A. Superheater 311 may enable removal of one or more components that may be included in other systems to protect a compressor, e.g., hot gas bypass or dumb valves.

[0108] Superheater 311 may further provide increased efficiency, e.g., by cooling liquid output by HP-OUT. Receiver 313 may obtain a mixture of phases, e g., both liquid and gas working fluid. Any gas included in receiver 313 will increase load on main compressor 322 without providing utility in an evaporator of fluid handling system 300A. Liquid in receiver 313 may be utilized for performing refrigeration (or other heat transfer) operations in the evaporators. Increasing a proportion of liquid in receiver 313 may improve efficiency of the system by producing less flash gas, which cannot be used for operations of the system until it is compressed. Rejecting heat from fluid provided by HP-OUT via superheater 311 before the fluid is provided to receiver 313 may increase a liquid portion of fluid in receiver 313 which may improve efficiency of the system.

[0109] Superheater 311 may be located along the fluid stream before main compressor 322. In other embodiments, superheater 311 may be located in a different location, e.g., along a flash gas outlet from receiver 313 (e.g., alternate position 396), coupled after a mediumtemperature evaporator (e.g., alternate position 397 located after evaporator 318), coupled after a low-temperature evaporator (e g., alternate position 398 located after second evaporator 319), before a secondary or low-temperature compressor 323, or the like.

[0110] Introduction of superheater 311 and subcooler 315 may provide additional stability to fluid handling system 300A. For example, superheater 311 and subcooler 315 may enable stable use of fluid handling system 300A in a variety of ambient temperatures (e.g., temperatures proximate main gas cooler 329). In particular, introduction of these components may allow stable operation of fluid handling system 300A in high ambient temperatures, and / or may improve overall system efficiency.

[0111] In some embodiments, introduction of superheater 311 may adjust properties of fluid provided to main compressor 322 (and / or low-temperature compressor 323, depending on location of the superheater). Temperature of suction flow to the main compressor 322 may be increased. Pressure of suction flow to the main compressor 322 may be increased.

[0112] Main compressor 322 suction superheat may be passively controlled, e.g., auxiliary high-pressure valve 369 may be controlled based on other factors, and superheat provided to the suction fluid of main compressor 322 may be based on the auxiliary high-pressure valve 369 operation. Main compressor 322 suction superheat may be actively controlled, e.g., with a hot gas bypass feeding hot compressor exit fluid back to suction, which may penalize system efficiency, to maintain target superheat.

[0113] Fluid handling system 300A further includes auxiliary high-pressure valve 369.Auxiliary high-pressure valve 369 may be a control valve, e.g., capable of allowing a target fluid flow through the auxiliary high-pressure valve 369. Auxiliary high-pressure valve 369 may be an auxiliary control valve. Auxiliary high-pressure valve 369 may be coupled between a high-pressure outlet of PX 310 and an inlet of receiver 313, e.g., either before or after superheater 311 (in reference to a fluid flow path). Auxiliary high-pressure valve 369 may instead or additionally be on a flow path including an auxiliary gas cooler. Auxiliary high-pressure valve 369 may be controlled based on sensor data of fluid handling system 300A, e.g., as described in FIG. 4A.

[0114] Fluid handling system 300A includes parallel valve 348. Parallel valve 348 may be a high-pressure valve (e.g., provided the same working fluid as provided to HP-IN). Parallel valve 348 may be used to bypass PX 310, e.g., in conditions where usage of PX 310 is inefficient, under conditions where PX 310 working volume is insufficient to achieve target conditions, or the like. Fluid handling system 300A may provide control to parallel valve 348, e.g., based on PX 310 operating speed, main gas cooler 329 pressure, or the like.

[0115] Described herein are references to “first fluid” and “second fluid.” In some embodiments, the first fluid and the second fluid are the same type of fluid (e.g., are a refrigeration fluid flowing in a fluid handling system). “First fluid” may refer to fluid flowing through the PX 310 from the high-pressure inlet to the low-pressure outlet of the PX 310 and / or fluid flowing to or from the high-pressure inlet and / or the low-pressure outlet of the PX 310. “Second fluid” may refer to fluid flowing through the PX 310 from the low-pressure inlet to the high-pressure outlet of the PX 310 and / or fluid flowing to or from the low- pressure inlet and / or the high-pressure outlet of the PX 310.

[0116] In some embodiments, fluid handling system 300A is a heat pump system capable of heating and cooling an environment (e.g., an indoor space). In some examples, one of main gas cooler 329 or evaporator 318 is an outdoor unit and the other of main gas cooler 329 or evaporator 318 is an indoor unit. In some examples, main gas cooler 329 is the outdoor unit (e.g., condensing unit) and evaporator 318 is the indoor unit (e.g., disposed in a refrigerated space, such as for storing food, medicine, sensitive chemicals or materials, etc ). The flow of fluid through the main gas cooler 329 and the evaporator 318 may be reversible (e.g., via a reversing valve coupled to the main compressor 322). The reversing valve may cause fluid flow exiting the main compressor 322 to be switchable between being directed towards the inlet of main gas cooler 329 (e.g., outdoor unit) or towards the inlet of the evaporator 318 (e.g., indoor unit). In some embodiments, one or more valves and piping may be used to cause fluid flow to be directed in the same direction through all of the components (e.g., one or more the PX 310, main compressor 322, and / or the like) while reversing fluid flow through the main gas cooler 329 and evaporator 318.

[0117] In some embodiments, a system described herein is a heat pump system capable of heating an environment (e.g., an indoor space). In such a heat pump system, the main gas cooler 329 is placed indoors and the evaporator 318 is placed outdoors. In a heat pump system, the evaporator absorbs heat from the ambient and may vaporize a two-phase refrigerant fluid flowing through the evaporator before sending it to the inlet of the compressor. In some embodiments, to switch from refrigeration or air-cooling system to a heat pump system, a reversing valve may be used to cause the fluid flow exiting the main compressor 322 to be switchable between being directed towards the inlet of the outdoor unit or towards the inlet of the indoor unit. In some embodiments, one or more valves and piping may be used to cause fluid flow to be directed in the same direction through all of the components (e.g., one or more the PX 310, main compressor 322, and / or the like) while switching the fluid flow from indoor unit to outdoor unit.

[0118] In some embodiments, the systems described herein (e.g., systems of one or more of FIGS. 3A-C can be used to heat an interior and / or enclosed space, to cool an interior and / or enclosed space, and / or selectively (e.g., reversibly) heat and cool a space.

[0119] FIG. 3B is a schematic diagram of a fluid handling system 300B that includes a pressure exchanger (PX 310) and low-pressure valve 326, according to some embodiments. In some embodiments, features that have reference numbers that correspond to reference numbers in other figures include similar properties, structures, and / or functionality as those described in other figures. In some embodiments, optional components described inconnection with FIG. 3A (e.g., secondary evaporator, a system of compressors in place of main compressor 322, etc.) may also be optional components for fluid handling system 300B. In some examples, features of fluid handling system 300B have similar properties, structures, and / or functionality as fluid handling system 300A of FIG. 3 A.

[0120] Fluid handling system 300B may be configured to provide heat transfer (e.g., refrigeration) via circulation of a working fluid (e g., CO2). Fluid handling system 300B may be configured to perform operations to adjust one or more components of fluid handling system 300B based on sensor data generated by sensors of fluid handling system 300B. In some embodiments, fluid handling system 300B may perform operations to achieve and / or maintain a target temperature of a target environment, such as an environment proximate evaporator 318 and / or second evaporator 319. Fluid handling system 300B may achieve a target temperature proximate evaporator 318 (e g., food refrigeration temperatures, first target refrigeration temperature) and a second target temperature proximate second evaporator 319 (e.g., freezer temperatures, second target refrigeration temperature).

[0121] In some embodiments, fluid handling system 300B may receive data indicative of conditions of the fluid handling system 300B, which may include working fluid conditions, ambient conditions, conditions proximate evaporators and / or gas coolers, etc. Fluid conditions may include temperature, pressure, mass flow rate, density, liquid level of a receiver, etc. Fluid handling system 300B may receive temperature data and / or other condition data from one or more sensors indicative of conditions of a fluid of fluid handling system 300B. Fluid handling system 300B may actuate one or more valves (e.g., parallel valve 348) based on the temperature data. Fluid handling system 300B may adjust one or more components to achieve and / or maintain a target fluid temperature, target fluid subcooling, or the like.

[0122] Fluid handling system 300B may include a parallel valve 348. Parallel valve 348 may be an expansion valve or a flow control valve. In some embodiments, parallel valve 348 selectively regulates a flow of fluid from the outlet of main gas cooler 329 (e.g., fluid discharged by main gas cooler 329) to receiver 313, e.g., in parallel with the PX 310. In some embodiments, parallel valve 348 can be actuated to selectively regulate the flow of fluid. Parallel valve 348 may selectively provide a portion of fluid output by the main gas cooler 329 to the receiver 313. For example, parallel valve 348 can be actuated to be further opened to flow more fluid from the main gas cooler 329 to the receiver 313, or parallel valve 348 can be actuated to be further closed to flow less fluid from the main gas cooler 329 to the receiver313. The fluid may expand as the fluid flows through parallel valve 348, causing a decrease in pressure and / or temperature of the fluid.

[0123] In some embodiments, main gas cooler 329 may act as a condenser. In some embodiments, the fluid handling system may be operated at pressured and temperatures where fluid does or does not condense in main gas cooler 329. Any embodiment discussed herein may include a condenser that may act as a gas cooler in one or more applications.

[0124] Fluid handling system 300B may include a receiver 313 (e.g., a flash tank). In some embodiments, receiver 313 is a receiver configured to receive a flow of fluid (e.g., first fluid) output from the low-pressure outlet of the PX 310. Receiver 313 may form a chamber to collect the first fluid from the first outlet of the PX 310. Receiver 313 may receive the first fluid in a two-phase state (e.g., liquid and gas), transcritical fluid, supercritical fluid, subcritical fluid, and / or combinations thereof. Receiver 313 may further receive fluid flow from auxiliary gas cooler 327, e.g., via auxiliary high-pressure valve 369. In some embodiments, receiver 313 (e.g., flash tank) is a tank constructed of welded sheet metal. Receiver 313 may include one or more flash tank inlets for receiving fluid and one or more flash tank outlets for discharging fluid (e.g., a gas outlet and a liquid outlet). The first fluid (at a low pressure) may separate into gas and liquid inside the receiver 313 (e g., indicated by the liquid surface depicted in FIG. 3B). The liquid of the first fluid may settle in the bottom of the receiver 313 while the gas of the first fluid may rise to the top of the receiver 313. The liquid may flow from receiver 313 towards evaporator 318 (e.g., via expansion valve 316). Liquid may flow from receiver 313 toward second evaporator 319, e.g., via secondary expansion valve 317. The chamber of receiver 313 may be maintained at a set pressure. The pressure may be set by a user (e.g., an operator, a technician, an engineer, etc.) and / or by a controller. In some embodiments, the pressure of the receiver 313 is controlled by one or more valves (e.g., expansion valve 316, flash gas valve 320, a pressure regulator valve, a safety valve, etc.). In some embodiments, the receiver 313 includes at least one pressure sensor (e.g., pressure transducer). In some embodiments, a liquid level of receiver 313 may be monitored (e.g., to prevent liquid from being routed through flash gas valve 320).

[0125] Fluid handling system 300B may include an expansion valve 316. Fluid handling system 300B may include secondary expansion valve 317. In some embodiments, expansion valve 316 is disposed along a flow path between receiver 313 and evaporator 318, e.g., coupled between receiver 313 and evaporator 318. Secondary expansion valve 317 may be coupled between receiver 313 and second evaporator 319. Expansion valve 316 may be an adjustable valve (e.g., an electronic expansion valve, a thermostatic expansions valve, a ballvalve, a gate valve, a poppet valve, etc.). Expansion valve 316 may be controllable by a user (e.g., a technician, an operator, an engineer, etc.) or by a controller. In some embodiments, the expansion valve 316 is caused to actuate by a controller based on sensor data (e g., pressure sensor data, flowrate sensor data, temperature sensor data, etc.). In some embodiments, expansion valve 316 is a thermal expansion valve. Expansion valve 316 may actuate (e g , open and / or close) based on temperature data associated with the evaporator 318 (e.g., temperature of liquid in the evaporator, temperature of gas in the evaporator, temperature of fluid entering the evaporator, temperature of fluid exiting the evaporator, etc.). For example, a pressure-sensitive component (e g., sensing bulb) of the expansion valve 316 may increase or decrease pressure on a diaphragm of the expansion valve 316, causing a poppet valve coupled to the diaphragm to open or close, thus causing more or less flow of fluid to the evaporator 318, causing more or less expansion of the fluid. The pressuresensitive component of the expansion valve may be positioned proximate to the downstream end of the evaporator 318 (e.g., proximate the outlet of the evaporator 318, outside evaporator 318, inside evaporator 318, or the like) and may be fluidly coupled to the diaphragm via a fluid line (e.g., a sensing capillary). In some embodiments, expansion valve 316 is controlled and actuated entirely based on electronic commands. Operations and control of secondary expansion valve 317 may be similar, e.g., in reference to conditions of fluid of second evaporator 319.

[0126] Fluid handling system 300B may include a flash gas valve 320 to regulate a flow of gas on a flash gas bypass flow path. In some embodiments, flash gas valve 320 is a bypass valve that regulates a flow of gas from a gas outlet of the receiver 313 to be combined with output of the evaporator 318. In some embodiments, the flow of gas from the receiver 313 flows along the flash gas bypass flow path to bypass the evaporator 318. In some embodiments, the flash gas flow path is between receiver 313 and a location downstream of an outlet of the evaporator 318. The gas flowing along the flash gas bypass flow path may be combined with output of the evaporator 318. The flash gas valve 320 may cause gas collected in the receiver 313 to expand (e.g., decrease in pressure) as the gas flows toward the main compressor 322. The flash gas valve 320 may, in some embodiments, be an adjustable valve. In some embodiments, the flash gas valve 320 is caused to actuate by a controller based on sensor data.

[0127] In some embodiments, a low-pressure outlet of PX 310 may be connected to receiver 313 via low-pressure valve 326. Low-pressure valve 326 may be used to maintain a pressure differential between the low-pressure side (e.g., low-pressure subsystem) of the PX310 and receiver 313. For example, receiver 313 may be maintained at a lower pressure than the low-pressure subsystem ofPX 310, such as 10 psi lower, 20 psi lower, 50 psi lower, 100 psi lower, or the like. Increasing the pressure of the low-pressure side of PX 310 may improve operation of the PX 310 (e.g., improving travel distance, efficiency, pressure exchange, decrease energy loss, etc.). In some embodiments, control of low-pressure valve326 may be performed based on sensor data, e g., sensor data related to pressure of fluid on the low-pressure side of the PX 310 and pressure data of fluid of receiver 313.

[0128] Fluid handling system 300B includes low-pressure booster 314. Low-pressure booster may be a booster, pump, compressor, lift device, etc , for increasing pressure of fluid provided at LP-IN of PX 310. In some embodiments, a need for a low-pressure booster (e.g., low-pressure booster 314) may be eliminated by other components, architectures, fluid flow paths, or the like. In some embodiments, control of one or more components may be based on operation of low-pressure booster 314. For example, fluid flow into LP-IN may be calculated based on operating speed of low-pressure booster 314, which may be used in control of other components (e.g., auxiliary high-pressure valve 369).

[0129] Fluid handling system 300B includes auxiliary gas cooler 327. Auxiliary gas cooler327 may provide some of the same benefits as the superheater 311 included in FIG. 3A, e.g., the auxiliary gas cooler 327 may cool fluid provided by HP-OUT, which may increase a proportion of liquid in receiver 313, may improve efficiency of fluid handling system 300B, etc. In some embodiments, architectures including low-pressure valve 326 may instead or additionally be combined with architectures including superheater 311, and / or superheaters disposed in other locations (e.g., alternate positions 396, 397, 398, etc.). Further, architectures including low-pressure valve 326 may be combined with subcooler 315, subcooling valve 312, etc.

[0130] FIG. 3C is a schematic diagram of a fluid handling system 300C that includes a subcooler 315, and a superheater 311, according to some embodiments. Features that have reference numbers that correspond to reference numbers in other figures may include similar properties, structures, and / or functionality as those described in other figures. In some embodiments, optional components described in connection with FIGS. 3A-B may also be optional components for fluid handling system 300C. Features of fluid handling system 300B may have similar properties, structures, and / or functionality as fluid handling systems 300A- B.

[0131] Fluid handling system 300C may be configured to provide heat transfer (e.g., refrigeration) via circulation of a working fluid (e.g., CO2 of one or more phases, such asliquid, gas, or supercritical fluid). Fluid handling system 300C may be configured to perform operations to adjust one or more components of fluid handling system 300C based on sensor data generated by sensors associated with fluid handling system 300C. Fluid handling system 300C may perform operations to achieve and / or maintain a target temperature of one or more environments, such as a building interior or freezer case of a grocery store. Fluid handling system 300C may perform operations to achieve and / or maintain target conditions of the fluid handling system, such as fluid temperature, pressure, density, liquid level, or the like at various locations of fluid handling system 300C. Fluid handling system 300C may adjust one or more components to achieve target conditions, such as actuating valves, adjusting a motor of PX 310, adjusting fan speeds, adjusting compressor speeds, or the like.

[0132] Fluid handling system 300C includes parallel valve 348. Parallel valve 348 may determine, at least in part, flow of working fluid into receiver 313. Parallel valve 348 may selectively provide a portion of fluid output by the main gas cooler 329 to receiver 313.

[0133] In some embodiments, main gas cooler 329 may act as a condenser. In some embodiments, the fluid handling system may be operated at pressured and temperatures where fluid does or does not condense in main gas cooler 329. Any embodiment discussed herein may include a condenser that may act as a gas cooler in one or more applications.

[0134] Fluid handling system 300C further includes receiver 313. Receiver 313 may receive fluid from a low-pressure outlet of PX 310, and from superheater 311. Receiver 313 may provide fluid to evaporator 318 for absorbing heat from an environment proximate evaporator 318, and / or to main compressor 322 via flash gas valve 320. Receiver 313 may enable separation of phases of working fluid of fluid handling system 300C.

[0135] Components and operations of components, such as auxiliary high-pressure valve 369, parallel valve 348, subcooler 315, etc., may share one or more features with corresponding components of FIG. 3B. For example, subcooler 315 may cause cooling of liquid provided to HP-IN of PX 310, by exchanging heat with a portion of fluid that is expanded through subcooling valve 312. Subcooler 315 may receive a portion of fluid to a secondary or cooling fluid channel for exchanging heat with fluid output by main gas cooler 329. A secondary or cooling fluid channel of subcooler 315 may receive fluid from auxiliary gas cooler 327, which may receive fluid from a high-pressure outlet of PX 310. In some embodiments, e.g., an architecture such as fluid handling system 300C, which lacks subcooling valve 312 of FIG. 3 A, subcooling may be uncontrolled, e.g., there may not be a control signal associated with monitoring and / or adjusting subcooling performed by subcooler 315. In some embodiments, as shown in FIG. 3C, the secondary or cooling channelmay receive a portion of fluid that is diverted from a primary stream after the primary stream travels through the primary channel of the subcooler 315. Subcooling valve 312 may expand a portion of fluid that has passed through subcooler 315 to cool additional fluid that is provided to subcooler 315 from main gas cooler 329. Obtaining cooling fluid for the secondary channel of subcooler 315 that has already passed through subcooler 315 may improve operation of subcooler 315 compared to other architectures. For example, fluid passing through subcooler 315 may be cooled by exchanging heat, then a portion further cooled by expanding through subcooling valve 312, which may cause working fluid provided to HP -IN to be a lower temperature than otherwise achieved

[0136] Further components of fluid handling system 300C, e.g., PX 310, main compressor 322, expansions valve 316, etc., may perform functions corresponding to their functions as described in connection with fluid handling systems 300A-B of FIGS. 3A-B.

[0137] An architecture including a superheater 311 (shown here in a different position than in FIG. 3 A, any relevant position may be used) may also include a subcooler 315. An architecture including a superheater 311 may also include a low-pressure booster. An architecture including a subcooler may also include an auxiliary gas cooler. In some embodiments, an auxiliary gas cooler and a superheater may be used, e g., some heat may be rejected by fluid exiting HP-OUT via the superheater, and additional fluid may be rejected in an auxiliary gas cooler. Any combinations of these components may be included with a valve for maintaining a pressure differential between receiver 313 and a low-pressure side of PX 310, e.g., as shown in FIG. 3B.

[0138] FIG. 4A is a schematic diagram of a fluid handling system 400A including PX 410, auxiliary gas cooler 427, and various controllers and other components for providing control of fluid handling system 400A, according to some embodiments.

[0139] Fluid handling system 400A includes components for performing heat transfer operations. Fluid handling system 400A includes PX 410, main gas cooler 429, auxiliary gas cooler 427, and evaporator 418. Fluid handling system 400A further includes receiver 413, flash gas valve 420, and expansion valve 416. Fluid handling system 400A further includes auxiliary high-pressure valve 469, main compressor 422, low-pressure valve 426, and bypass high-pressure valve 428. Components of fluid handling system 400A may share one or more features with corresponding components of fluid handling systems 300A-C of FIGS. 3A-C.

[0140] Fluid handling system 400A may include one or more sensors. The one or more sensors measure property values associated with the system. For example, one or more temperature sensors may measure temperature of a flowing fluid, of the environment, of hotand / or cold sinks associated with the system, etc. One or more pressure gauges may measure pressure of a fluid of fluid handling system 400A. One or more flow meters may measure flow (e.g., mass flow) of fluid through fluid handling system 400A. Fluid handling system 400A may utilize flow rate data from a flow meter to determine one or more operations, including operation of one or more components of the fluid handling system, such as auxiliary high-pressure valve 469. One or more density meters (e g., two phase fluid density meters, two phase density meters, Coriolis flow meters, etc.) may measure density of a fluid of fluid handling system 400A. Other sensors (e.g., meters) may measure additional property values, e g., work performed by various components, heat flow through the system, power consumed by components of the system, total fluid flow through various portions of the system, etc. Depicted in FIG. 4A are gauge 480, gauge 481, and gauge 482. In some embodiments, a depiction of a gauge may indicate the inclusion of multiple instruments, e.g., a gauge to determine volumetric flow may include a device for measuring mass flow and a device for measuring density of a fluid. In some cases, one or more sensors may not be depicted for visual clarity of FIGS. 4A-B.

[0141] Fluid handling system 400A includes controllers 490, and 491. Controllers of fluid handling system 400A may be PID controllers. Controllers of fluid handling system 400A may perform operations based on a known relationship between sensor data and control output, e.g., via a lookup table, functional form of the relationship, or the like.

[0142] Control of fluid handling system 400A may be performed by computing devices, e.g., general purpose computing devices (desktop computers, laptop computers, tablets, smart phones, etc.) executing instructions to perform control tasks. Control of fluid handling system 400A may be performed by purpose-built computing devices. Control of fluid handling system 400A may be performed by control devices such as PID controllers, microcontrollers, or other known methods for providing control signals. Control of fluid handling system 400A may include devices performing multiple operations, such as a single device executing operations of controller 490 and controller 491, a single device executing operations of all controllers of fluid handling system 400A, or any permutation of functions of various controllers being performed by combinations of computing devices.

[0143] Controller 490 is operatively coupled to auxiliary high-pressure valve 469. Controller 490 may receive one or more measurements form one or more gauges (e.g., sensors) of the fluid handling system 400A. Controller 490 may generate and / or provide one or more control signals to auxiliary high-pressure valve 469 based on the one or more sensor measurements. In a first example, controller 490 may receive an indication of fluid flow anduse the indication of fluid flow to determine an opening of auxiliary high-pressure valve 469. Controller 490 may receive flow rate data from a flow meter and generate a control signal for auxiliary high-pressure valve 469 based on the flow rate data. The indication of fluid flow may be based on a flow meter, e.g., measuring flow of fluid to LP-IN or flow of fluid from HP-OUT. In another example, speed of operation of one or more pumps may be utilized to determine fluid flow, e.g., operating speed of low-pressure booster 414 may be used to determine fluid flow and / or to generate a control signal by controller 490 to adjust operation of auxiliary high-pressure valve 469. Operating speed data of a pump, compressor, booster, or the like may be utilized by controller 490 to generate a control signal for auxiliary high- pressure valve 469. Further fluid properties may be used in conjunction with operating speed of low-pressure booster, such as pressure of fluid provided to low-pressure booster 414 or output by low-pressure booster 414, temperature of fluid provided to low-pressure booster 414 or output by low-pressure booster 414, or the like.

[0144] In some embodiments, an approach may use sensors that may be easily and efficiently installed. For example, PX 410 may be added to an existing refrigeration system (e.g., the parent rack) to improve performance of the existing system. It may be of interest to obtain data from easily accessible components or components installed along with PX 410, e.g., avoiding expensive sensors (e.g., flow meters) and / or avoiding relying on sensors of the parent rack, which may be difficult to access, of uncertain quality, or the like. In some embodiments, controller 490 may obtain data indicative of fluid properties at HP-IN, e.g., fluid properties at the outlet of main gas cooler 429. Fluid properties may be obtained by gauge 480. In some embodiments, gauge 480 may be or include a temperature sensor, and controller 490 may generate control signals for auxiliary high-pressure valve 469 based on temperatures measured by gauge 480. In some embodiments, fluid temperature data associated with the working fluid at the outlet of main gas cooler 429 may be utilized by controller 490 in determining or generating a control signal for auxiliary high-pressure valve 429. In some embodiments, fluid properties may be derived based on ambient conditions, e.g., conditions proximate main gas cooler 429. For example, assumptions and / or calculations may be utilized, determining that fluid temperature of working fluid leaving main gas cooler 429 is the same as ambient temperature, a function of ambient temperature (e.g., a few degrees higher than ambient temperature), or the like. Such a measurement (e.g., via gauge 480) may be used in combination with a subcooler in some embodiments.

[0145] In some embodiments, controller 490 may further obtain data from PX 410. For example, controller 490 may obtain operating speed data from PX 410. Information related toproperties of fluid provided to HP-IN and operating speed of PX 410 may be utilized in determining fluid properties at HP-OUT (e.g., it may be assumed that fluid properties at HP- OUT are a function of HP-IN, such as assuming a pressure differential between the two, which may vary based on conditions), which may be utilized by controller 490 in generating control signals for auxiliary high-pressure valve 469.

[0146] In some embodiments, auxiliary gas cooler 427 may expel heat to the same environment as main gas cooler 429. Assumptions may be employed that correlate properties (e.g., temperature) of working fluid output by auxiliary gas cooler 427 to properties of working fluid output by main gas cooler 429 (e g., as measured by gauge 480). Properties of fluid provided to auxiliary high-pressure valve 469 may be determined, e.g., by controller 490 based on gauge 480, PX 410, etc. Properties of fluid (e g., fluid pressure) after auxiliary high-pressure valve 469 may further be measured (e g., by gauge 482), which may also be incorporated by controller 490 in generating a control signal for operation of auxiliary high- pressure valve 469.

[0147] Controller 491 may be operatively coupled to low-pressure valve 426. Low-pressure valve 426 may be configured to maintain a target pressure differential (e.g., 10 psi, 20 psi, 40 psi, 50 psi, 100 psi, or any other target pressure differential) between a low-pressure side (e.g., LP-OUT) of PX 410 and receiver 413. Controller 491 may obtain pressure measurements indicative of properties of fluid on the low-pressure side of PX 410 and properties of fluid of receiver 413. Controller 491 may generate a control signal and provide the control signal to low-pressure valve 426 based on the pressure measurements, to maintain a target pressure differential between the low-pressure side of PX 410 and receiver 413.

[0148] A fluid handling system (e.g., refrigeration system) may include devices for performing operations of any combination of the above-described controllers. A fluid handling system may include devices performing operations of controller 490. A fluid handling system may include devices performing operations of controller 491. A fluid handling system may include sensors gauges, or other instrumentation in connection with any of the controllers described herein. A fluid handling system may include devices performing operations of any one of these controllers, any two of these controllers (e.g., controllers 490 and 491), etc. A fluid handling system may include any combination of inputs to controller 490, e.g., flow meter inputs and compressor speed inputs, described above, gauge 480 and PX 410 inputs, shown, etc. Any combination of these controllers may be included in a fluid handling system (e.g., refrigeration system).

[0149] In some embodiments, a controller (e.g., a central controller, a system controller, which may be combined with one or more of controllers 490 through 491) receives sensor data indicative of a temperature of a refrigerated space (e g., the cold reservoir proximate evaporator 418) and / or a temperature of a heated space (e.g., the hot reservoir proximate main gas cooler 429). The controller may control auxiliary high-pressure valve 469, low- pressure valve 426, etc., based on sensor data received from one or more sensors of the fluid handling system 400A (e.g., one or more fluid flowrate sensors, temperature sensors, pressure sensors, etc ). In some embodiments, one or more sensors (e g., pressure sensors, flow sensors, temperature sensors, etc.) are disposed proximate inlets and / or outlets of the various components of the fluid handling system 400A (e.g., fluids discharged from various components). In some embodiments, one or more sensors are disposed internal to the components of the fluid handling system 400A. In some embodiments, a pressure sensor may be disposed proximate the inlet of the main compressor 422 and an additional pressure sensor may be disposed proximate the outlet of the main compressor 422. In some embodiments, a temperature sensor may be disposed proximate the inlet of the evaporator 418 and another temperature sensor may be disposed proximate the outlet of the evaporator 418 (e.g., for measuring temperature of fluid discharged from evaporator 418). In some embodiments, a temperature sensor may be disposed internal to the main gas cooler 429 and / or auxiliary gas cooler 427. In some embodiments, a flow sensor may be located at each of the inlets and outlets of the PX 410 to measure a flow of the first fluid and the second fluid into and out of the PX 410.

[0150] In some embodiments, a controller (e.g., a central controller, a system controller, which may be combined with one or more of controllers 490 through 491, and / or additional controllers) receives sensor data indicative of a temperature of a refrigerated space (e.g., a cold reservoir proximate evaporator 418) and / or a temperature of a heated space (e.g., a hot reservoir proximate main gas cooler 429). The controller may control auxiliary high-pressure valve 469, PX 410, main compressor 422, low-pressure booster 414, low-pressure valve 426 or any other controllable components of a fluid handling system based on sensor data received from one or more sensors of the fluid handling system (e.g., one or more fluid flowrate sensors, temperature sensors, pressure sensors, etc.). In some embodiments, one or more sensors (e.g., pressure sensors, flow sensors, temperature sensors, etc.) are disposed proximate inlets and / or outlets of the various components of the fluid handling system 400A (e.g., fluids discharged from various components). In some embodiments, one or more sensors are disposed internal to the components of the fluid handling system 400A. In someembodiments, a pressure sensor may be disposed proximate the inlet of the main compressor 422 and an additional pressure sensor may be disposed proximate the outlet of the main compressor 422. In some embodiments, a temperature sensor may be disposed proximate the inlet of the evaporator 418 and another temperature sensor may be disposed proximate the outlet of the evaporator 418 (e g., for measuring temperature of fluid discharged from evaporator 418). In some embodiments, a temperature sensor may be disposed internal to the main gas cooler 429 and / or auxiliary gas cooler 427. In some embodiments, a flow sensor may be located at each of the inlets and outlets of the PX 410 to measure a flow of the first fluid and the second fluid into and out of the PX 410.

[0151] FIG. 4B is a schematic diagram of a fluid handling system 400B including sensors and controllers, according to some embodiments. Fluid handling system 400B includes similar components to fluid handling system 300C of FIG. 3C Components of fluid handling system 400B may share one or more features, functions, or properties of corresponding components of fluid handling system 300C. Fluid handling system 400B includes a number of sensors, e g., gauge 483, gauge 484. Sensors may share one or more features, functions, or properties with sensors included in fluid handling system 400A of FIG. 4A. Fluid handling system 400B includes a number of controllers, such as controller 492. Controllers may include or share features and / or properties with controllers included in fluid handling system 400B, such as architecture of the controllers, potential grouping of controller functions by a smaller number of computing devices, or the like. Some controllers may be applicable to various types of architectures, and controllers may be used together in any combination relevant for a target fluid handling system architecture. For example, an architecture such as fluid handling system 400B may benefit from a controller directed toward low-pressure control valve, such as controller 491 of FIG 4A. Any number of controllers described herein may be included in a target architecture and may be executed by any number of devices.

[0152] Fluid handling system 400B includes main gas cooler 429, PX 410, subcooler 415, subcooling valve 412, superheater 411, receiver 413, flash gas valve 420, expansion valve 416, second expansion valve 417, evaporator 418, second evaporator 419, low-temperature compressor 423, and main compressor 422. These components may perform similar functions to corresponding components of fluid handling system 300A or 400A.

[0153] Fluid handling system 400B may include gauge 483 and gauge 484. The gauges of fluid handling system 400B may include similar characteristics to gauges of fluid handling system 400A. Each gauge of fluid handling system 400B may include a number of sensors, meters, or other instruments for determining measurements related to control of fluidhandling system 400B. A gauge may include one or more temperature sensors, pressure sensors, flow meters, density meters, or the like.

[0154] Fluid handling system 400B includes controller 492. Controller 492 may be used to provide control signals for adjusting operation of auxiliary high-pressure valve 469. As described with connection to fluid handling system 400A, controller 492 may provide control signals to auxiliary high-pressure valve 469 based on measurements indicative of properties of working fluid, e.g., working fluid provided to HP-IN, and / or working fluid on either side of auxiliary high-pressure valve 469. In some embodiments (e g., when a refrigeration system includes a superheater), assumptions regarding a relationship between working fluid output by main gas cooler 429 and fluid provided to auxiliary high-pressure valve 469 may not be valid. Gauge 483 may be used to provide information about fluid conditions at the exit of main gas cooler 429. In some embodiments, fluid temperature data associated with the working fluid at an inlet or suction-side of main compressor 422 may be utilized by controller 492 in generating a control signal for auxiliary gas cooler 469. The temperature of fluid output by an outlet of superheater 411 may be indicative of temperature of fluid provided to auxiliary high-pressure valve 469, e.g., they may be the same temperature, they may be related by an algebraic relationship, or the like. In some embodiments, gauge 483 may instead be coupled after subcooler 415, e.g., adjacent HP-IN. Gauge 484 may provide a temperature measurement of fluid provided to main compressor 422. Conditions of fluid provided to main compressor 422 may be indicative of properties of fluid that has passed through superheater 411, e.g., fluid temperatures of the two outlet streams of superheater 411 may be equivalent, may be related, etc. In some embodiments (e.g., when superheater 411 is disposed in a different location), gauge 484 may measure properties of fluid elsewhere, e g., proximate an outlet of a channel of superheater 411. In some embodiments, gauge 484 may instead measure fluid properties of fluid provided to auxiliary high-pressure valve 469.

[0155] In some embodiments, an opening of auxiliary high-pressure valve 469 may be based on an opening of subcooling valve 412. For example, a function relating target flow through the auxiliary high-pressure control valve based on properties of the auxiliary high- pressure control valve, properties of the subcooling valve 412, and opening of the subcooling valve 412 may be used by controller 492 in determining an opening of auxiliary high- pressure valve 469. Actuation data associated with actuation of a bypass valve, e.g., subcooling valve 412, may be utilized by controller 492 in determining an opening of auxiliary high-pressure valve 469. Utilizing an opening of subcooling valve 412 to determine an opening of auxiliary high-pressure valve 469 may be of particular interest when fluidstreams provided to the valves may be related, e.g., assumed to be the same temperature, related by an algebraic expression, or the like. For example, a fluid handling system including an auxiliary gas cooler and a subcooling valve 412 may provide input fluid to the valves at approximately the same temperature, and an expression relating predicted flow through the two valves may be utilized by controller 492 in generating a control signal. In some cases, e g., if subcooling valve 412 and auxiliary high-pressure valve 469 are the same model of valve, a simple expression may be used, such as opening auxiliary high-pressure valve 469 to match the opening of subcooling valve 412, auxiliary high-pressure valve 469 opening being a few percent different than opening of subcooling valve 412 (e g., to account for inefficiencies in the fluid handling system), or the like. Generating the control signal may include utilizing a function relating subcooling valve 412 opening to auxiliary high-pressure valve 469 opening, consulting a lookup table, or the like to determine a target opening of auxiliary high-pressure valve 469.

[0156] FIGS. 5A-B are flow diagrams illustrating methods 500A-B for controlling fluid handling systems (e.g., one or more of fluid handling systems 300A-C of FIGS. 3A-C), according to some embodiments. In some embodiments, methods 500A-B are performed by processing logic that includes hardware (e.g., circuitry, dedicated logic, programmable logic, microcode, processing device, etc.), software (such as instructions run on a processing device, run on a processor such as a central processing unit or graphics processing unit, a general purpose computer system, or a dedicated machine), firmware, microcode, or a combination thereof. In some embodiments, methods 500A-B are performed, at least in part, by one or more controllers. In some embodiments, a non-transitoiy storage medium stores instructions that when executed by one or more processing, cause the processing device to perform methods 500A-B.

[0157] For simplicity of explanation, methods 500A-B are depicted and described as a series of operations. However, operations in accordance with this disclosure can occur in various orders and / or concurrently and with other operations not presented and described herein. Furthermore, in some embodiments, not all illustrated operations are performed to implement methods 500A-B in accordance with the disclosed subject matter. In addition, those skilled in the art will understand and appreciate that methods 500A-B are could alternatively be represented as a series of interrelated states via a state diagram or events.

[0158] FIG. 5A is a flow diagram of a method 500A for providing control of a fluid handling system, according to some embodiments. At block 502, processing logic (e.g., a processing device, a controller, a computer processor, etc.) obtains an indication of propertiesof working fluid of a refrigeration system provided to an inlet of a PX. The properties of the working fluid may include measurements by one or more flow meters configured to determine mass flow of working fluid provided by the high-pressure outlet of the PX (e.g., flow meter coupled to LP-IN, flow meter coupled to HP-OUT, or the like). The properties of working fluid may include a speed of operation of a pump providing working fluid to a low- pressure inlet of the PX, e.g., a low-pressure booster. The properties of working fluid may include measurements of working fluid temperature at an outlet of a gas cooler of the refrigeration system, at high-pressure inlet of the PX, or being provided to a compressor of the system, such as a main compressor or a low-temperature compressor.

[0159] At block 504, process logic generates a first control signal based on the indication of properties of the working fluid at the inlet of the PX. Generating the first control signal may optionally be based on further inputs, e.g., a speed of operation of the PX, conditions of working fluid in other portions of the refrigeration system, etc. For example, conditions of working fluid provided to one or more compressors, conditions of fluid on either side of an auxiliary high-pressure valve (e.g., a high-pressure control valve), or the like may be used in generating the control signal. In some embodiments, the high-pressure control valve may be configured to regulate flow of the working fluid through the first channel of a heat exchanger (e.g., superheater). In some embodiments, the second channel of the heat exchanger may be coupled between one or more evaporators and one or more compressors, e.g., between a low- temperature evaporator and a low-temperature compressor, between an evaporator and a main compressor, or the like. In some embodiments, the second channel of the heat exchanger may be coupled before a compressor, e.g., between a flash gas valve and a main compressor. In some embodiments, the heat exchanger may be configured to transfer heat from fluid in the first channel (e.g., provided via HP-OUT) to fluid in the second channel (e.g., provided to a compressor of the refrigeration system).

[0160] At block 506, process logic provides the first control signal to the high-pressure control valve fluidly coupled between HP-OUT and a receiver. The fluid path between HP- OUT and the receiver may further include the heat exchanger, an auxiliary gas cooler, or the like. The high-pressure control valve may be configured to adjust operation of the high- pressure control valve based on the first control signal.

[0161] At block 508, process logic optionally obtains an indication of a pressure differential between the receiver and the low-pressure inlet of the PX. The low-pressure outlet pressure may be measured directly, may be based on pressure at a low-pressure inlet of the PX, may be calculated based on low-pressure booster speed and / or PX speed, or the like.The pressure of the receiver may be provided by a pressure gauge or other pressure sensor associated with the receiver.

[0162] At block 510, process logic optionally generates a second control signal based on the pressure differential. The second control signal may be based on comparing the pressure differential to a target pressure differential. The target pressure differential may be a single value, or may vary based on conditions, e.g., ambient conditions, fluid conditions, evaporator conditions, heat exchanger conditions, or the like. The target pressure differential may be determined via one or more functions, look-up tables, or the like.

[0163] At block 512, process logic provides the second control signal to a second control valve. The second control valve is fluidly coupled between a low-pressure outlet of the PX and the receiver. The second control valve may be configured to maintain a pressure differential between a low-pressure side of the PX and the receiver, e g., to maintain a higher pressure in the low-pressure side of the PX than in the receiver. The second control valve is configured to adjust operation of the second control valve (e.g., opening %) based on the control signal.

[0164] FIG. 5B is a flow diagram of a method 500B for providing control of a refrigeration system, according to some embodiments. At block 520, process logic obtains an indication of a pressure differential between a receiver of a refrigeration system and a low-pressure subsystem of a PX of the refrigeration system.

[0165] At block 522, process logic generates a first control signal based on the indication of the pressure differential. Generating the first control signal optionally further includes comparing the pressure differential to a target pressure differential.

[0166] At block 524, process logic provides the first control signal to a control valve. The control valve is fluidly coupled between a low-pressure outlet of the PX and the receiver. The control valve is configured to maintain a pressure differential between the low-pressure side of the PX and the receiver. The control valve is configured to adjust operation of the control valve (e.g., opening %) based on the first control signal.

[0167] At block 526, process logic optionally further generates a second control signal. The second control signal may be based on an indication of PX operating speed. The second control signal may be based on temperature of fluid, e.g., fluid provided to a high-pressure inlet of the PX, fluid provided to a compressor of the refrigeration system, or the like. The fluid provided to the compressor may be provided to the compressor from an outlet of a heat exchanger (e.g., superheater). The fluid provided to the compressor may be heated byexchanging heat in the heat exchanger with fluid provided to the heat exchanger from HP- OUT of the PX.

[0168] At block 528, process logic provides the second control signal to a high-pressure control valve. The high-pressure control valve is configured to regulate flow of working fluid between a high-pressure outlet of the PX and the receiver. The high-pressure control valve is configured to adjust operation of the high-pressure control valve based on the control signal

[0169] FIG. 6 is a block diagram illustrating a computer system 600, according to some embodiments. In some embodiments, the computer system 600 is a client device. In some embodiments, the computer system 600 is a controller device (e.g., server, control module, central control system, controllers 490-492 of FIGS. 4A-B, etc.).

[0170] In some embodiments, computer system 600 is connected (e.g., via a network, such as a Local Area Network (LAN), an intranet, an extranet, or the Internet) to other computer systems. Computer system 600 operates in the capacity of a server or a client computer in a client-server environment, or as a peer computer in a peer-to-peer or distributed network environment. In some embodiments, computer system 600 is provided by a personal computer (PC), a tablet PC, a Set-Top Box (STB), a Personal Digital Assistant (PDA), a cellular telephone, a web appliance, a server, a network router, switch or bridge, or any device capable of executing a set of instructions (sequential or otherwise) that specify actions to be taken by that device. Further, the term "computer" shall include any collection of computers that individually or jointly execute a set (or multiple sets) of instructions to perform any one or more of the methods described herein.

[0171] In some embodiments, the computer system 600 includes a processing device 602, a volatile memory 604 (e.g., Random Access Memory (RAM)), a non-volatile memory 606 (e.g., Read-Only Memory (ROM) or Electrically-Erasable Programmable ROM (EEPROM)), and / or a data storage device 616, which communicates with each other via a bus 608.

[0172] In some embodiments, processing device 602 is provided by one or more processors such as a general purpose processor (such as, for example, a Complex Instruction Set Computing (CISC) microprocessor, a Reduced Instruction Set Computing (RISC) microprocessor, a Very Long Instruction Word (VLIW) microprocessor, a microprocessor implementing other types of instruction sets, or a microprocessor implementing a combination of types of instruction sets) or a specialized processor (such as, for example, an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA), a Digital Signal Processor (DSP), a PID controller, or a network processor). In someembodiments, processing device 602 is provided by one or more of a single processor, multiple processors, a single processor having multiple processing cores, and / or the like.

[0173] In some embodiments, computer system 600 further includes a network interface device 622 (e.g., coupled to network 674). In some embodiments, the computer system 600 includes one or more input / output (I / O) devices. In some embodiments, computer system 600 also includes a video display unit 610 (e g., a liquid crystal display (LCD)), an alphanumeric input device 612 (e.g., a keyboard), a cursor control device 614 (e.g., a mouse), and / or a signal generation device 620. Computer system 600 may include signal input device 615, e g., for receiving signals from other devices. For example, signal input device 615 may facilitate reception by computer system 600 of measurement data from sensors associated with a fluid handling system. Signal generation device 620 may be utilized to generate and / or send control signals for sending instmctions to one or more components of a fluid handling system. Signal generation device 620 may send control signals to various high-pressure valves, booster pumps, cooling components, PX components, etc.

[0174] In some implementations, data storage device 616 (e.g., disk drive storage, fixed and / or removable storage devices, fixed disk drive, removable memory card, optical storage, network attached storage (NAS), and / or storage area-network (SAN)) includes a non- transitory computer-readable storage medium 624 on which stores instructions 626 encoding any one or more of the methods or functions described herein, and for implementing methods described herein. Control module 633 (e.g., including any of controllers 490-492 of FIGS. 4A-B, executing methods of FIGS. 5A-B, etc.) may be included in instructions 626.

[0175] In some embodiments, instructions 626 also reside, completely or partially, within volatile memory 604 and / or within processing device 602 during execution thereof by computer system 600, hence, volatile memory 604 and processing device 602 also constitute machine-readable storage media, in some embodiments.

[0176] While computer-readable storage medium 624 is shown in the illustrative examples as a single medium, the term "computer-readable storage medium" shall include a single medium or multiple media (e.g., a centralized or distributed database, and / or associated caches and servers) that store the one or more sets of executable instructions. The term "computer-readable storage medium" shall also include any tangible medium that is capable of storing or encoding a set of instructions for execution by a computer that cause the computer to perform any one or more of the methods described herein. The term "computer- readable storage medium" shall include, but not be limited to, solid-state memories, optical media, and magnetic media.

[0177] The methods, components, and features described herein may be implemented by discrete hardware components or may be integrated in the functionality of other hardware components such as ASICs, FPGAs, DSPs or similar devices. In addition, the methods, components, and features may be implemented by firmware modules or functional circuitry within hardware devices. Further, the methods, components, and features may be implemented in any combination of hardware devices and computer program components, or in computer programs.

[0178] Unless specifically stated otherwise or clear from context, terms such as “actuating,” “adjusting,” “causing,” “controlling,” “determining,” “identifying,” “providing,” “receiving,” “generating,” “obtaining,” or the like, refer to actions and processes performed or implemented by computer systems that manipulates and transforms data represented as physical (electronic) quantities within the computer system registers and memories into other data similarly represented as physical quantities within the computer system memories or registers or other such information storage, transmission or display devices. Also, the terms "first," "second," "third," "fourth," etc. as used herein are meant as labels to distinguish among different elements and may not have an ordinal meaning according to their numerical designation.

[0179] Examples described herein also relate to an apparatus for performing the methods described herein. This apparatus may be specially constructed for performing the methods described herein, or it may include a general purpose computer system selectively programmed by a computer program stored in the computer system. Such a computer program may be stored in a computer-readable tangible storage medium.

[0180] The methods and illustrative examples described herein are not inherently related to any particular computer or other apparatus. Various general purpose systems may be used in accordance with the teachings described herein, or it may prove convenient to construct more specialized apparatus to perform methods described herein and / or each of their individual functions, routines, subroutines, or operations. Examples of the structure for a variety of these systems are set forth in the description above.

[0181] The preceding description sets forth numerous specific details, such as examples of specific systems, components, methods, and so forth, in order to provide a good understanding of several embodiments of the present disclosure. It will be apparent to one skilled in the art, however, that at least some embodiments of the present disclosure may be practiced without these specific details. In other instances, well-known components or methods are not described in detail or are presented in simple block diagram format in orderto avoid unnecessarily obscuring the present disclosure. Thus, the specific details set forth are merely exemplary. Particular implementations may vary from these exemplary details and still be contemplated to be within the scope of the present disclosure. Descriptions of systems herein may include descriptions of one or more optional components. Components may be included in combinations not specifically discussed in this disclosure, and still be within the scope of this disclosure. For example, any of controllers 390-395 of FIGS. 3A-D, alone or in any combination, may be included in a fluid handling system that is within the scope of this disclosure.

[0182] Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrase “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. In addition, the term “or” is intended to mean an inclusive “or” rather than an exclusive “or.” When the term “about,” “substantially,” or “approximately” is used herein, this is intended to mean that the nominal value presented is precise within ±10%. Also, the terms "first," "second," "third," "fourth," etc. as used herein are meant as labels to distinguish among different elements and can not necessarily have an ordinal meaning according to their numerical designation.

[0183] The terms “over,” “under,” “between,” “disposed on,” “before,” “after,” and “on” as used herein refer to a relative position of one material layer or component with respect to other layers or components. For example, one layer disposed on, over, or under another layer may be directly in contact with the other layer or may have one or more intervening layers. Moreover, one layer disposed between two layers may be directly in contact with the two layers or may have one or more intervening layers. Similarly, unless explicitly stated otherwise, one feature disposed between two features may be in direct contact with the adjacent features or may have one or more intervening layers or components.

[0184] Although the operations of the methods herein are shown and described in a particular order, the order of the operations of each method may be altered so that certain operations may be performed in an inverse order or so that certain operation may be performed, at least in part, concurrently with other operations. In another embodiment, instructions or sub-operations of distinct operations may be in an intermittent and / or alternating manner.

[0185] It is to be understood that the above description is intended to be illustrative, and not restrictive. Many other embodiments will be apparent to those of skill in the art upon readingand understanding the above description. The scope of the disclosure should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which each claim is entitled.

Claims

CLAIMSWhat is claimed is:

1. A system comprising: a pressure exchanger (PX) configured to receive a first fluid, receive a second fluid, and exchange pressure between the first fluid and the second fluid; a first heat exchanger configured to receive the second fluid from the PX via a first inlet of the first heat exchanger, receive a third fluid via a second inlet of the first heat exchanger, and exchange heat between the second fluid and the third fluid; and a first compressor configured to receive the third fluid from the first heat exchanger.

2. The system of claim 1, further comprising a first evaporator, wherein an outlet of the first evaporator is fluidly coupled to the second inlet of the first heat exchanger.

3. The system of claim 2, further comprising a second evaporator and a second compressor, wherein an outlet of the second evaporator is fluidly coupled to an inlet of the second compressor, and wherein an outlet of the first compressor is fluidly coupled to an inlet of the second compressor.

4. The system of claim 2, wherein an outlet of the first compressor is fluidly coupled to an inlet of a gas cooler, and wherein the gas cooler is configured to provide the first fluid to the PX.

5. The system of claim 2, further comprising a second evaporator, wherein an outlet of the second evaporator is fluidly coupled to the second inlet of the first heat exchanger.

6. The system of claim 2, further comprising a second evaporator, wherein an outlet of the second evaporator is fluidly coupled to an inlet of the first compressor.

7. The system of claim 1, further comprising: a receiver; and an evaporator, wherein the third fluid is provided to the first heat exchanger from the receiver, and wherein an outlet of the evaporator is fluidly coupled to an inlet of the first compressor.

8. The system of claim 1, further comprising: a gas cooler, configured to receive fluid from the first compressor; and a second heat exchanger, wherein an outlet of the gas cooler is fluidly coupled to a first inlet of the second heat exchanger, and wherein a first outlet of the second heat exchanger, fluidly coupled to the first inlet of the second heat exchanger, is configured to provide the first fluid to the PX9. The system of claim 8, wherein the outlet of the gas cooler is further fluidly coupled to a second inlet of the second heat exchanger, and wherein a second outlet of the second heat exchanger corresponding to the second inlet of the second heat exchanger is configured to provide the second fluid to the PX.

10. The system of claim 8, wherein the first outlet of the second heat exchanger is further fluidly coupled to a second inlet of the second heat exchanger, and wherein a second outlet of the second heat exchanger, corresponding to the second inlet of the second heat exchanger, is configured to provide the second fluid to the PX.

11. The system of claim 1, further comprising a pump configured to provide the second fluid to the PX.

12. The system of claim 11, further comprising a receiver, wherein the pump is configured to obtain the second fluid from the receiver, and wherein the receiver is configured to receive the first fluid from the PX.

13. The system of claim 1, further comprising: a receiver; and a control valve, coupled between the PX and the receiver, wherein the first fluid is to be provided from the PX to the receiver through the control valve.

14. The system of claim 13, further comprising a controller, operatively coupled to the control valve, wherein the controller is configured to adjust operation of the control valve to maintain a pressure differential between the receiver and a first outlet of the PX, associated with the first fluid.

15. The system of claim 1, further comprising a high-pressure control valve, wherein the high-pressure control valve is configured to regulate flow of fluid through the first heat exchanger.

16. The system of claim 15, wherein the high-pressure control valve is to be operated to enable mass flow through the high-pressure control valve to correspond to mass flow into a low-pressure inlet of the PX.

17. The system of claim 16, further comprising a second control valve that regulates flow of the second fluid into the PX, wherein control of the high-pressure control valve is based on an opening of the second control valve.

18. The system of claim 16, further comprising a pump configured to provide the second fluid to the PX, wherein control of the high-pressure control valve is based on an operating speed of the pump.

19. The system of claim 16, wherein control of the high-pressure control valve is based on flow meter measurements of fluid provided to a low-pressure inlet of the PX.

20. A method comprising: obtaining, by a processing device, an indication of properties of a working fluid of a refrigeration system provided to an inlet of a pressure exchanger (PX); generating a first control signal based on the indication of properties of the working fluid at the inlet of the PX; and providing the first control signal to a high-pressure control valve fluidly coupled between a high-pressure outlet of the PX and a receiver, wherein the high-pressure control valve is configured to adjust operation of the high-pressure control valve based on the first control signal.

21. The method of claim 20, wherein the high-pressure control valve is configured to regulate flow of the working fluid through a first channel of a heat exchanger coupled between the high-pressure outlet of the PX and the receiver, and wherein a second channel of the heat exchanger is fluidly coupled between an evaporator of the refrigeration system and a compressor of the refrigeration system, and wherein the heat exchanger is configured toexchange heat between working fluid in the first channel and working fluid in the second channel.

22. The method of claim 21, wherein the indication of properties of the working fluid comprises one or more measurements by a flow meter configured to determine mass flow of working fluid provided by the high-pressure outlet of the PX.

23. The method of claim 21, wherein the indication of properties of the working fluid comprises an operating speed of a pump coupled to provide working fluid to a low-pressure inlet of the PX.

24. The method of claim 21, wherein the indication of properties of the working fluid comprises a measurement of working fluid temperature at an outlet of a gas cooler of the refrigeration system.

25. The method of claim 21, wherein the generating of the first control signal is further based on a measurement of temperature of the working fluid at an inlet of the compressor of the refrigeration system.

26. The method of claim 20, wherein the indication of properties of the working fluid comprises a fluid temperature associated with corresponding fluid flow through a high- pressure inlet of the PX, and wherein the first control signal is further based on a speed of operation of the PX.

27. The method of claim 26, wherein the first control signal is further based on a fluid temperature associated with respective fluid flow through the high-pressure control valve.

28. The method of claim 27, wherein the fluid temperature of the high-pressure control valve is determined based on a temperature measurement of working fluid provided to an inlet of a compressor of the refrigeration system, the working fluid provided to the inlet of the compressor having exchanged heat in a heat exchanger with working fluid flowing through the high-pressure control valve.

29. The method of claim 26, wherein the refrigeration system comprises a main gas cooler, and the high-pressure control valve is fluidly coupled with an auxiliary gas cooler of the refrigeration system.

30. The method of claim 20, wherein the indication of properties of the working fluid of the refrigeration system comprises an indication of an opening of a bypass valve, wherein the bypass valve regulates first mass flow of the working fluid to a low-pressure inlet of the pressure exchanger and second mass flow of the working fluid to a secondary channel of a heat exchanger, the heat exchanger being configured to exchange heat between working fluid output by a main gas cooler of the refrigeration system and the working fluid of the secondary channel of the heat exchanger.

31. The method of claim 30, wherein the generating of the first control signal comprises utilizing the indication of the opening of the bypass valve as input to a function or lookup table to determine a target opening of the high-pressure control valve.

32. The method of claim 20, further comprising: obtaining an indication of a pressure differential between the receiver and a low- pressure outlet of the PX; generating a second control signal based on the indication of the pressure differential; and providing the second control signal to a second control valve fluidly coupled between a low-pressure outlet of the PX and the receiver, wherein the second control valve is to adjust operation of the second control valve based on the second control signal.

33. The method of claim 32, wherein the generating of the second control signal comprises comparing the pressure differential to a target pressure differential.

34. A method, comprising: obtaining, by a processing device, an indication of a pressure differential between a receiver of a refrigeration system, and a low-pressure subsystem associated with a pressure exchanger (PX) of the refrigeration system; generating, based on the indication of the pressure differential, a first control signal; andproviding the first control signal to a control valve fluidly coupled between a low- pressure outlet of the PX and the receiver, wherein the control valve is configured to adjust operation of the control valve based on the first control signal.

35. The method of claim 34, wherein generating the first control signal comprises comparing the pressure differential to a target pressure differential.

36. The method of claim 34, further comprising: generating a second control signal; and providing the second control signal to a high-pressure control valve, wherein the high- pressure control valve is configured to regulate flow of working fluid between a high- pressure outlet of the PX and the receiver.

37. The method of claim 36, wherein generating the second control signal is based on an indication of PX operating speed and a temperature of fluid provided to a high-pressure inlet of the PX.

38. The method of claim 36, wherein generating the second control signal is based on an indication of PX operating speed and a temperature of fluid provided to a compressor of the refrigeration system, wherein the refrigeration system comprises a heat exchanger configured to exchange heat between working fluid output by the high-pressure outlet of the PX, and working fluid provided to an inlet of the compressor.

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