Transcritical refrigeration pressure exchanger

Abstract

A pressure exchanger (PX) includes a rotor configured to receive a first fluid, receive a second fluid, and exchange pressure between the first fluid and the second fluid, where the rotor forms a plurality of ducts. The PX further includes a first end cover fluidly coupled with the rotor, the first end cover forming a first kidney, where a kidney angular extent of the first kidney is substantially an integer multiple of a duct angular spacing between at least two adjacent ducts of the plurality of ducts, where the kidney angular extent is an angular distance between an opening edge and a closing edge of the first kidney and the duct angular spacing is an angular distance between corresponding centers of the at least two adjacent ducts.

Description

RELATED APPLICATIONS

[0001] This is a national stage application under 35 U.S.C. 371 of International Application PCT / US23 / 81213, filed Nov. 27, 2023, which claims benefit to U.S. Provisional Patent Application No. 63 / 428,260, filed Nov. 28, 2022, the contents of each are incorporated by reference in their entirety herein.TECHNICAL FIELD

[0002] The present disclosure relates to pressure exchangers (PXs), and, more particularly, PXs used in refrigeration systems.BACKGROUND

[0003] Systems use fluids at different pressures. Systems use components to increase pressure of fluid.BRIEF DESCRIPTION OF THE DRAWINGS

[0004] The present disclosure is illustrated by way of example, and not by way of limitation in the figures of the accompanying drawings.

[0005] FIGS. 1A-D illustrate schematic diagrams of fluid handling systems including hydraulic energy transfer systems, according to certain embodiments.

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

[0007] FIGS. 3A-B illustrate PXs including end covers forming kidneys and rotors forming ducts, according to some embodiments.

[0008] FIG. 3C illustrates an end cover, according to some embodiments.

[0009] FIG. 3D illustrates a seal plate, according to some embodiments.

[0010] FIG. 4 illustrates end covers, according to some embodiments.

[0011] FIG. 5 illustrates an end cover, according to some embodiments.

[0012] FIG. 6 illustrates an end cover including a buffer chamber, according to some embodiments.

[0013] FIG. 7A illustrates a PX having a rotor and end covers, according to some embodiments.

[0014] FIG. 7B illustrates a PX having a rotor and end covers, according to some embodiments.

[0015] FIG. 8A illustrates a PX having a rotor and end covers, according to some embodiments.

[0016] FIG. 8B illustrates a PX having a rotor and end covers, according to some embodiments.

[0017] FIG. 9 illustrates a rotor forming ducts, according to some embodiments.

[0018] FIG. 10 illustrates an end cover forming a pre-pressurization hole, according to some embodiments.

[0019] FIG. 11 illustrates a spot face of an end cover, according to certain embodiments.DETAILED DESCRIPTION OF EMBODIMENTS

[0020] Embodiments described herein are related to transcritical refrigeration PXs.

[0021] 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 hydraulic fracturing (e.g., fracking or fracing) systems, desalinization systems, refrigeration systems, heat pump systems, energy generation systems, mud pumping systems, slurry pumping systems, industrial fluid systems, waste fluid systems, fluid transportation systems, etc. Pumps or compressors may be used to increase pressure of fluids of such systems.

[0022] Conventionally, 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, capillaries or orifices. 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). In some embodiments, the present disclosure is directed to a high performance transcritical carbon dioxide (CO2) PX design. The PX of the present disclosure may be used for transcritical CO2 refrigeration and / or heat pump applications.

[0023] The systems, devices, and methods of the present disclosure provide PXs for use in systems (e.g., fluid handling systems, heat transfer systems, refrigeration systems, heat pump systems, cooling systems, heating systems, etc.). 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 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). The PX may be a rotary PX that exchanges pressure energy between two streams of a transcritical gas (e.g., CO2 in either liquid, gas, or a mixture of the two phases).

[0024] Some systems (e.g., PX based heat transfer systems) may have high vibration levels at input and / or output ports (e.g., of the PX) that exceed standards (e.g., American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) standards) for refrigeration compressors. Some systems may also have high noise levels that exceed the limits adhered to by most of the compressor equipment manufacturers. Some systems (e.g., PX based systems) may not reduce energy consumption effectively due to various losses expansion losses, mixing losses, internal leakage losses and pressure losses. Some systems (e.g., PX based systems) do not mitigate mixing effectively resulting in increased enthalpy dilution at high pressure out kidneys (HPOUT kidneys) and diminished liquid fraction at low pressure out kidneys (LPOUT kidneys) diminishing PX energy savings. Some systems (e.g., PX based systems) may have high pressure drop across the PX (especially at higher flows and RPMs) resulting in increased compressor work and diminished energy savings. Some systems (e.g., PX based systems) may have high leakage through the PX bearings causing decreased refrigerant flow through the rotor decreasing energy recovery. Some systems (e.g., PX based systems) may have higher risk of cavitation and can diminish bearing stiffness / load capability.

[0025] Systems of the present disclosure may solve one or more of these and other problems. Systems of the present disclosure reduce wear on components (e.g., pumps, compressors) compared to conventional systems. Systems of the present disclosure reduce mixing in the transcritical CO2 PX resulting in reduced enthalpy dilution at HPOUT and enhanced liquid fraction at LPOUT, enhancing PX energy savings compared to conventional systems. Systems of the present disclosure reduce pressure drop across the PX (especially at higher flows and RPMs) resulting in reduced booster work and enhanced energy savings compared to conventional systems. Systems of the present disclosure reduce leakage through the PX bearings enabling increased refrigerant flow through the rotor, thereby increasing energy recovery compared to conventional systems (e.g., conventional PX based systems). The present disclosure can reduce the risk of cavitation and can enhance bearing stiffness / load capability compared to conventional systems (e.g., conventional PX based systems). Using end covers with reduced thickness and eliminating the carrier plate results in a shorter and stiffer drive train compared to conventional systems (e.g., conventional PX based systems).

[0026] In some embodiments, a PX includes one or more of the features described in one or more of FIGS. 3A-11.

[0027] In some embodiments, a PX includes a rotor configured to receive a first fluid, receive a second fluid, and exchange pressure between the first fluid and the second fluid. The rotor forms a plurality of ducts. The PX further includes a first end cover fluidly coupled with the rotor, the first end cover forming a first kidney, where a kidney angular extent of the first kidney is substantially an integer multiple of a duct angular spacing between at least two adjacent ducts of the plurality of ducts. In some embodiments, the kidney angular extent is an angular distance between an opening edge and a closing edge of the first kidney and a duct angular extent is an angular distance between corresponding centers of the at least two adjacent ducts.

[0028] In some embodiments, the PX includes a second end cover that forms a second kidney, where a delay angle between the first kidney and the second kidney ranges from 15 to 20 degrees. In some embodiments, the delay angle is an angular distance between a closing edge of the second kidney and a closing edge of the first kidney. In some embodiments, a similar delayed opening may be present on the first kidney in the second end cover. In some embodiments, a similar delayed opening may be present a third kidney formed by the first end cover and a fourth kidney formed by the second end.

[0029] In some embodiments, the rotor forms the ducts in a plurality of concentric rows. The ducts in two rows being staggered.

[0030] In some embodiments, the PX includes a second end cover, where the second end cover forms a second kidney. In some embodiments, the second kidney may have a delayed opening with respect to the first kidney formed by the first end cover. The first end cover includes a first end cover surface that faces the rotor, the first end cover surface forming a buffer chamber disposed in a delay region of the first end cover. In some embodiments, the delay region is a region between an opening edge of the second kidney and an opening edge of the first kidney.

[0031] In some embodiments, the first end cover forms a third kidney. In some embodiments, fluid flow between ports of the PX and the rotor is through the first kidney and the third kidney. In some embodiments, a ratio of a size of the first kidney to a size of the third kidney ranges from 3:2 to 5:2.

[0032] In some embodiments, a PX includes a rotor configured to receive a first fluid, receive a second fluid, and exchange pressure between the first fluid and the second fluid. In some embodiments, the rotor forms a plurality of ducts. The pressure exchanger further includes a first end cover fluidly coupled with the rotor, the first end cover comprising a first end cover surface that faces the rotor. The first end cover surface forms a buffer chamber disposed in the delay region of the first end cover. In some embodiments, the PX includes a second end cover forming a second kidney, where the delay region is a region between an opening edge of the second kidney and an opening edge of the first kidney.

[0033] In some embodiments, the PX further includes a second end cover fluidly coupled to the rotor, the second end cover forming a third kidney. In some embodiments, when a first duct of the plurality of ducts substantially aligns with the buffer chamber, the third kidney substantially aligns with the first duct.

[0034] In some embodiments, the first duct and a second duct of the plurality of ducts substantially align with the buffer chamber simultaneously while the third kidney substantially aligns with the first duct.

[0035] In some embodiments, the third kidney is a high pressure out (HPOUT) kidney and the first and second ducts are low-pressure ducts.

[0036] In some embodiments, the first kidney is a high pressure in (HPIN) kidney, and the first duct substantially aligns with the first kidney after aligning with the buffer chamber.

[0037] In some embodiments, the third kidney is a low pressure out (LPOUT) kidney and the first and second ducts are high pressure ducts.

[0038] In some embodiments, the first kidney is a low pressure in (LPIN) kidney, and the first duct substantially aligns with the first kidney after aligning with the buffer chamber.

[0039] In some embodiments, a kidney angular extent of the first kidney is substantially an integer multiple of a duct angular spacing between at least two adjacent ducts of the plurality of ducts. In some embodiments, the kidney angular extent is an angular distance between an opening edge and a closing edge of the first kidney and the duct angular extent is an angular distance between corresponding centers of the at least two adjacent ducts.

[0040] In some embodiments, the buffer chamber is a substantially similar shape as the first kidney and has an angular extent substantially equal to or substantially double an angular extent of a rotor duct of the plurality of rotor ducts.

[0041] In some embodiments, the first end cover forms a third kidney. In some embodiments, fluid flow between ports of the PX and the rotor is through the first kidney and the third kidney. In some embodiments, a ratio of a size of the first kidney to a size of the third kidney ranges from 3:2 to 5:2.

[0042] In some embodiments, a PX includes a rotor configured to receive a first fluid, receive a second fluid, and exchange pressure between the first fluid and the second fluid. The PX further includes a first end cover fluidly coupled with the rotor, the first end cover forming a first kidney and a second kidney. In some embodiments, fluid flow between ports of the PX and the rotor is through the first kidney and the second kidney. In some embodiments, a ratio of a size of the first kidney to a size of the second kidney ranges from 3:2 to 5:2.

[0043] In some embodiments, the first kidney is a high-pressure kidney, and the second kidney is a low-pressure kidney.

[0044] In some embodiments, the PX further includes a second end cover fluidly coupled with the rotor, the second end cover forming a third kidney and a fourth kidney. In some embodiments, fluid flow between ports of the PX and the rotor is through the third kidney and the fourth kidney. In some embodiments, a ratio of a size of the third kidney to a size of the fourth kidney ranges from 3:2 to 5:2.

[0045] In some embodiments, the third kidney is a high-pressure kidney, and the fourth kidney is a low-pressure kidney.

[0046] In some embodiments, the rotor forms a plurality of ducts. In some embodiments, a kidney angular extent of the first kidney is substantially an integer multiple of a duct angular extent between at least two adjacent ducts of the plurality of ducts. In some embodiments, the rotor forms a plurality of ducts. In some embodiments, a kidney angular extent of the first kidney is substantially an integer multiple of the angular spacing between at least two adjacent ducts of the plurality of ducts. In some embodiments, the kidney angular extent is an angular distance between an opening edge and a closing edge of the first kidney and the duct angular extent is an angular distance between corresponding centers of the at least two adjacent ducts.

[0047] 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. For example, use of a PX 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 system. Systems of the present disclosure reduce mixing in the transcritical CO2 PX resulting in reduced enthalpy dilution at HPOUT and enhanced liquid fraction at LPOUT enhancing PX energy savings compared to conventional systems. Systems of the present disclosure reduce pressure drop across the PX (especially at higher flows and RPMs) resulting in reduced booster work and enhanced energy savings compared to conventional systems. Systems of the present disclosure reduce leakage through the PX bearings enabling increased refrigerant flow through the rotor increasing energy recovery compared to conventional systems. The present disclosure can reduce the risk of cavitation and can enhance bearing stiffness / load capability compared to conventional systems. Using end covers with reduced thickness and eliminating the carrier plate results in a shorter and stiffer drive train compared to conventional systems.

[0048] Although some embodiments of the present disclosure are described in relation to PXs, energy recovery devices, and hydraulic energy transfer systems, the current disclosure can be applied to other systems and devices (e.g., PX that is not isobaric, rotating components that are not a PX, a PX that is not rotary, systems that do not include PXs, etc.).

[0049] 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.

[0050] FIGS. 1A-D illustrate schematic diagrams of fluid handling systems 100 including hydraulic energy transfer systems 110, according to certain embodiments.

[0051] In some embodiments, a hydraulic energy transfer system 110 includes a PX (e.g., PX). The PX may include one or more of the features described in one or more of FIGS. 3A-11.

[0052] The hydraulic energy transfer system 110 (e.g., PX) receives low-pressure (LP) fluid in 120 (e.g., low-pressure inlet stream) from a LP in system 122. The hydraulic energy transfer system 110 also receives high pressure (HP) fluid in 130 (e.g., high-pressure inlet stream) 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., low-pressure outlet stream) to LP fluid out system 142 and to provide HP fluid out 150 (e.g., high-pressure outlet stream) to HP fluid out system 152.

[0053] 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. The PX may be a device that transfers fluid pressure between HP fluid in 130 and LP fluid in 120 at efficiencies 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 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 the like. 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. Rotary PXs may be designed to operate with internal pistons to isolate fluids and transfer pressure with relatively little mixing of the inlet fluid streams. Reciprocating PXs may include a piston moving back and forth in a cylinder for transferring pressure between the fluid streams. Any PX or multiple PXs may be used in the present disclosure, such as, but not limited to, rotary PXs, reciprocating 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 100 (e.g., in situations in which the PX is added to an existing fluid handling system).

[0054] 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 in 130, etc.). In some embodiments, motor 160 generates energy (e.g., acts as a generator) based on pressure exchanging in hydraulic energy transfer system 110.

[0055] The hydraulic energy transfer system 110 may be a hydraulic protection system (e.g., hydraulic buffer system, hydraulic isolation system) that may block or limit contact between solid particle laden fluid (e.g., frac fluid) and various equipment (e.g., hydraulic fracturing equipment, high-pressure pumps) while exchanging work and / or pressure with another fluid. By blocking or limiting contact between various equipment (e.g., fracturing equipment) and solid particle containing fluid, the hydraulic energy transfer system 110 increases the life and performance, while reducing abrasion and wear, of various equipment (e.g., fracturing equipment, high pressure fluid pumps). Less expensive equipment may be used in the fluid handling system 100 by using equipment (e.g., high pressure fluid pumps) not designed for abrasive fluids (e.g., frac fluids and / or corrosive fluids).

[0056] The hydraulic energy transfer system 110 may include a hydraulic turbocharger or hydraulic pressure exchange system, such as a rotating PX. The PX may include one or more chambers (e.g., 1 to 100) to facilitate pressure transfer and equalization of pressures between volumes of first and second fluids (e.g., gas, liquid, multi-phase fluid). In some embodiments, the PX may transfer pressure between a first fluid (e.g., pressure exchange fluid, such as a proppant free or substantially proppant free fluid) and a second fluid that may be highly viscous and / or contain solid particles (e.g., frac fluid containing sand, proppant, powders, debris, ceramics). The solid particle fluid causes abrasion and / or erosion of components of the PX, such as the rotor and end covers of the PX. The fluid (e.g., abrasive particles in the fluid) may cause wear to an interface between the rotor and each end cover as the rotor rotates relative to the end covers. Replacing worn components of the PX may be costly.

[0057] The hydraulic energy transfer system 110 may be used in different types of systems, such as fracing systems, desalination systems, refrigeration systems, etc.

[0058] FIG. 1A illustrates a schematic diagram of a fluid handling system 100A including a hydraulic energy transfer system 110, according to certain embodiments. Fluid handling system 100A may include a control module 180 that includes one or more controllers 185.

[0059] FIG. 1B 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 a fracing system. In some embodiments, fluid handling system 100B includes more components, less components, same routing, different routing, and / or the like than that shown in FIG. 1B.

[0060] LP fluid in 120 and HP fluid out 150 may be frac fluid (e.g., fluid including solid particles, proppant fluid, etc.). HP fluid in 130 and LP fluid out 140 may be substantially solid particle free fluid (e.g., proppant free fluid, water, filtered fluid, etc.).

[0061] LP in system 122 may include one or more low-pressure fluid pumps to provide LP fluid in 120 to the hydraulic energy transfer system 110 (e.g., PX). HP in system 132 may include one or more high pressure fluid pumps 134 to provide HP fluid in 130 to hydraulic energy transfer system 110.

[0062] Hydraulic energy transfer system 110 exchanges pressure between LP fluid in 120 (e.g., low-pressure frac fluid) and HP fluid in 130 (e.g., high pressure water) to provide HP fluid out 150 (e.g., high pressure frac fluid) to HP out system 152 and to provide LP fluid out 140 (e.g., low-pressure water). HP out system 152 may include a rock formation 154 (e.g., well) that includes cracks 156. The solid particles (e.g., proppants) from HP fluid out 150 may be provided into the cracks 156 of the rock formation.

[0063] In some embodiments, LP fluid out 140, high pressure fluid pumps 134, and HP fluid in 130 are part of a first loop (e.g., proppant free fluid loop). The LP fluid out 140 may be provided to the high-pressure fluid pumps to generate HP fluid in 130 that becomes LP fluid out 140 upon exiting the hydraulic energy transfer system 110.

[0064] In some embodiments, LP fluid in 120, HP fluid out 150, and low-pressure fluid pumps 124 are part of a second loop (e.g., proppant containing fluid loop). The HP fluid out 150 may be provided into the rock formation 154 and then pumped from the rock formation 154 by the low-pressure fluid pumps 124 to generate LP fluid in 120.

[0065] In some embodiments, fluid handling system 100B is used in well completion operations in the oil and gas industry to perform hydraulic fracturing (e.g., fracking, fracing) to increase the release of oil and gas in rock formations 154. HP out system 152 may include rock formations 154 (e.g., a well). Hydraulic fracturing may include pumping HP fluid out 150 containing a combination of water, chemicals, and solid particles (e.g., sand, ceramics, proppant) into a well (e.g., rock formation 154) at high pressures. LP fluid in 120 and HP fluid out 150 may include a particulate laden fluid that increases the release of oil and gas in rock formations 154 by propagating and increasing the size of cracks 156 in the rock formations 154. The high pressures of HP fluid out 150 initiates and increases size of cracks 156 and propagation through the rock formation 154 to release more oil and gas, while the solid particles (e.g., powders, debris, etc.) enter the cracks 156 to keep the cracks 156 open (e.g., prevent the cracks 156 from closing once HP fluid out 150 is depressurized).

[0066] In order to pump this particulate laden fluid into the rock formation 154 (e.g., a well), the fluid handling system 100B may include one or more high pressure fluid pumps 134 and one or more low-pressure fluid pumps 124 coupled to the hydraulic energy transfer system 110. For example, the hydraulic energy transfer system 110 may be a hydraulic turbocharger or a PX (e.g., a rotary PX). In operation, the hydraulic energy transfer system 110 transfers pressures without any substantial mixing between a first fluid (e.g., HP fluid in 130, proppant free fluid) pumped by the high-pressure fluid pumps 134 and a second fluid (e.g., LP fluid in 120, proppant containing fluid, frac fluid) pumped by the low-pressure fluid pumps 124. In this manner, the hydraulic energy transfer system 110 blocks or limits wear on the high-pressure fluid pumps 134, while enabling the fluid handling system 100B to pump a high-pressure frac fluid (e.g., HP fluid out 150) into the rock formation 154 to release oil and gas. In order to operate in corrosive and abrasive environments, the hydraulic energy transfer system 110 may be made from materials resistant to corrosive and abrasive substances in either the first or second fluids. For example, the hydraulic energy transfer system 110 may be made out of ceramics (e.g., alumina, cermets, such as carbide, oxide, nitride, or boride hard phases) within a metal matrix (e.g., Co, Cr or Ni or any combination thereof) such as tungsten carbide in a matrix of CoCr, Ni, NiCr or Co.

[0067] In some embodiments, the hydraulic energy transfer system 110 includes a PX (e.g., rotary PX) and HP fluid in 130 (e.g., the first fluid, high-pressure solid particle free fluid) enters a first side of the PX where the HP fluid in 130 contacts LP fluid in 120 (e.g., the second fluid, low-pressure frac fluid) entering the PX on a second side. The contact between the fluids enables the HP fluid in 130 to increase the pressure of the second fluid (e.g., LP fluid in 120), which drives the second fluid out (e.g., HP fluid out 150) of the PX and down a well (e.g., rock formation 154) for fracturing operations. The first fluid (e.g., LP fluid out 140) similarly exits the PX, but at a low pressure after exchanging pressure with the second fluid. As noted above, the second fluid may be a low-pressure frac fluid that may include abrasive particles, which may wear the interface between the rotor and the respective end covers as the rotor rotates relative to the respective end covers.

[0068] FIG. 1C illustrates a schematic diagram of a fluid handling system 100C including a hydraulic energy transfer system 110, according to certain embodiments. Fluid handling system 100C may be a desalination system (e.g., remove salt and / or other minerals from water). In some embodiments, fluid handling system 100C includes more components, less components, same routing, different routing, and / or the like than that shown in FIG. 1C.

[0069] LP in system 122 may include a feed pump 126 (e.g., low-pressure fluid pump 124) that receives seawater in 170 (e.g., feed water from a reservoir or directly from the ocean) and provides LP fluid in 120 (e.g., low-pressure seawater, feed water) to hydraulic energy transfer system 110 (e.g., PX). HP in system 132 may include membranes 136 that provide HP fluid in 130 (e.g., high pressure brine) to hydraulic energy transfer system 110 (e.g., PX). The hydraulic energy transfer system 110 exchanges pressure between the HP fluid in 130 and LP fluid in 120 to provide HP fluid out 150 (e.g., high pressure seawater) to HP out system 152 and to provide LP fluid out 140 (e.g., low-pressure brine) to LP out system 142 (e.g., geological mass, ocean, sea, discarded, etc.).

[0070] The membranes 136 may be a membrane separation device configured to separate fluids traversing a membrane, such as a reverse osmosis membrane. Membranes 136 may provide HP fluid in 130 which is a concentrated feed-water or concentrate (e.g., brine) to the hydraulic energy transfer system 110. Pressure of the HP fluid in 130 may be used to compress low-pressure feed water (e.g., LP fluid in 120) to be high pressure feed water (e.g., HP fluid out 150). For simplicity and illustration purposes, the term feed water is used. However, fluids other than water may be used in the hydraulic energy transfer system 110.

[0071] The circulation pump 158 (e.g., turbine) provides the HP fluid out 150 (e.g., high pressure seawater) to membranes 136. The membranes 136 filter the HP fluid out 150 to provide LP potable water 172 and HP fluid in 130 (e.g., high pressure brine). The LP out system 142 provides brine out 174 (e.g., to geological mass, ocean, sea, discarded, etc.).

[0072] In some embodiments, a high-pressure fluid pump 176 is disposed between the feed pump 126 and the membranes 136. The high-pressure fluid pump 176 increases pressure of the low-pressure seawater (e.g., LP fluid in 120, provides high pressure feed water) to be mixed with the high-pressure seawater provided by circulation pump 158.

[0073] In some embodiments, use of the hydraulic energy transfer system 110 decreases the load on high pressure fluid pump 176. In some embodiments, fluid handling system 100C provides LP potable water 172 without use of high-pressure fluid pump 176. In some embodiments, fluid handling system 100C provides LP potable water 172 with intermittent use of high-pressure fluid pump 176.

[0074] In some examples, hydraulic energy transfer system 110 (e.g., PX) receives LP fluid in 120 (e.g., low-pressure feed-water) at about 30 pounds per square inch (PSI) and receives HP fluid in 130 (e.g., high-pressure brine or concentrate) at about 980 PSI. The hydraulic energy transfer system 110 (e.g., PX) transfers pressure from the high-pressure concentrate (e.g., HP fluid in 130) to the low-pressure feed-water (e.g., LP fluid in 120). The hydraulic energy transfer system 110 (e.g., PX) outputs HP fluid out 150 (e.g., high pressure (compressed) feed-water) at about 965 PSI and LP fluid out 140 (e.g., low-pressure concentrate) at about 15 PSI. Thus, the hydraulic energy transfer system 110 (e.g., PX) may be about 97% efficient since the input volume is about equal to the output volume of the hydraulic energy transfer system 110 (e.g., PX), and 965 PSI is about 97% of 980 PSI.

[0075] FIG. 1D illustrates a schematic diagram of a fluid handling system 100D including a hydraulic energy transfer system 110, according to certain embodiments. Fluid handling system 100D may be a refrigeration system. In some embodiments, fluid handling system 100D includes more components, less components, same routing, different routing, and / or the like than that shown in FIG. 1D.

[0076] Hydraulic energy transfer system 110 (e.g., PX) may receive LP fluid in 120 from LP in system 122 (e.g., low-pressure lift device 128, low-pressure fluid pump, etc.) and HP fluid in 130 from HP in system 132 (e.g., condenser 138). 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., high pressure lift device 159) and to provide LP fluid out 140 to LP out system 142 (e.g., evaporator 144). The evaporator 144 may provide the fluid to compressor 178 and low-pressure lift device 128. The condenser 138 may receive fluid from compressor 178 and high-pressure lift device 159.

[0077] The fluid handling system 100D 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) that is circulated in the closed system of fluid handling system 100D.

[0078] In some embodiments, the fluid of fluid handling system 100D may include solid particles. For example, the piping, equipment, connections (e.g., pipe welds, pipe soldering), etc. may introduce solid particles (e.g., solid particles from the welds) into the fluid in the fluid handling system 100D. The solid particles in the fluid and / or the high pressure of the fluid may cause abrasion and / or erosion of components (e.g., rotor, end covers) of the PX of hydraulic energy transfer system 110.

[0079] FIGS. 2A-E are exploded perspective views of a rotary PX 40 (e.g., rotary PX, rotary liquid piston compressor (LPC)), according to certain embodiments. PX 40 may include a motor 92 and / or a control module 94.

[0080] In some embodiments, PX 40 includes one or more of the features described in one or more of FIGS. 3A-11.

[0081] PX 40 is configured to transfer pressure and / or work between a first fluid (e.g., proppant free fluid or supercritical carbon dioxide, HP fluid in 130) and a second fluid (e.g., frac fluid or 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), 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. Similarly, the inlet port 60 may receive a low-pressure second fluid (e.g., LP fluid in 120) and the outlet port 62 may be used to route a high-pressure second fluid (e.g., 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.

[0082] As noted above, 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.

[0083] 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).

[0084] In some embodiments, a controller using sensor feedback (e.g., revolutions per minute measured through a tachometer or optical encoder or volume flow rate measured through flowmeter) may 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-D of FIGS. 1A-D). For example, varying the volume flow rates of the first and second fluids entering the rotary PX 40 allows the plant operator (e.g., system operator) to control the amount of fluid mixing within the PX 40. In addition, varying the rotational speed of the rotor 46 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 fluid barrier (e.g., an 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 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, a small portion of the rotor channel 70 is used for the exchange of pressure between the first and second fluids. Therefore, 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.

[0085] 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 that shown in FIGS. 2A-2E. As described in detail below, the rotary PX 40 facilitates pressure exchange between first and second fluids by enabling the first and second fluids to briefly contact each other within the rotor 46. In certain 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 the rotational speed of rotor 46 dictate whether any mixing occurs and to what extent.

[0086] 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. As will be discussed below, the rotor 46 may rotate in the clockwise direction indicated by arrow 84. In operation, low-pressure second fluid 86 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 and the first fluid 88.

[0087] 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 rotated clockwise 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.

[0088] 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.

[0089] 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.

[0090] Abrasion and / or erosion damage in a PX may occur when suspended solids are introduced and mixed in the fluid that enters the PX. Abrasion damage may occur when particles enter gaps in the PX (e.g., trapped between a stationary end cover and a rotating end cover). Erosion damage may occur due to existence of suspended solids (e.g., erodents) in high velocity fluid jets (e.g., slurry jets) that are formed due to the high pressure differentials inside the PX. When the high velocity jet makes an impact with components of the PX, the high velocity jet can cause damage to those components. Damage (e.g., erosion damage) can occur when a high-pressure rotor port (e.g., rotor duct) opens to a low-pressure end cover port (e.g., kidney) or when a low-pressure rotor port (e.g., rotor duct) opens to a high pressure end cover port (e.g., kidney) which causes a high pressure differential.

[0091] The PX of the present disclosure may have lower vibration levels at HPIN, HPOUT and LPOUT ports (e.g., within ASHRAE standards for refrigeration compressors) compared to conventional systems. The PX of the present disclosure may have lower noise levels (e.g., within limits adhered by compressor manufacturers) compared to conventional systems. The PX of the present disclosure may reduce mixing in the transcritical CO2 PX which may result in reduced enthalpy dilution at HPOUT and enhanced liquid fraction at LPOUT which may enhance PX energy savings. The present disclosure may reduce pressure drop across the PX (e.g., at higher flows and RPMs) which may result in reduced booster work and enhanced energy savings. The present disclosure may reduce leakage through the PX bearings which may enable increased refrigerant flow through the rotor increasing energy recovery. The present disclosure may reduce risk of cavitation and may enhance bearing stiffness and / or load capacity (e.g., of the PX). The present disclosure may have a reduced thickness of end covers and may reduce or eliminate the carrier plate which may result in a shorter and stiffer drive train and enhanced performance. The present disclosure may mate with a housing (e.g., redesigned housing) that enables an increase in HPOUT flow velocity which may reduce the chances of oil separation and accumulation in the PX.

[0092] In some embodiments, the present disclosure incudes a device (rotary PX) that exchanges pressure energy between two streams of CO2 in either liquid, gas or a mixture of the two phases.

[0093] FIGS. 3A-B illustrate PXs including end covers forming kidneys and rotors forming ducts, according to some embodiments.

[0094] In some embodiments, at least one of an HPIN, HPOUT, LPIN, or LPOUT kidney angular extents (e.g., an angular distance between an opening edge and a closing edge of a kidney) may be integral multiples of the duct angular extent (e.g., the spacing between adjacent ducts). In some embodiments, an angular extent can be a measure of the size or magnitude of an angle, typically in degrees, radians, or other angular units, which describes the amount of rotation or separation between two lines or rays that share a common vertex (e.g., an opening edge and a closing edge of a kidney). For example, if you have a circle (e.g., an end cover), the angular extent of a sector (a portion of the circle) is measured in degrees or radians and represents the angle formed by the two radii that define the sector. A full circle has an angular extent of 360 degrees (or 2π radians). If a sector covers only a fraction of the full circle, its angular extent is a proportion of 360 degrees (or 2π radians), depending on the fraction of the circle it represents. In some embodiments, an angular distance, when referring to a circle, can be the measure of the angle formed by two lines (or rays) that have their starting point at the center of the circle and extend to two different points on the circumference of the circle. This angle is typically measured in degrees or radians and tells you how far apart those two points are as you travel along the edge of the circle from one point to the other.

[0095] In some embodiments, integral multiples may also be referred to as integer multiples, whole-number multiples, etc. In mathematics, an integer can be a whole number. When you multiply a first integer by a second integer, the result is also an integer. When a first integer is multiplied by a second integer the resulting product is said to be an integer multiple (integral multiple) of both the first and second integers. For example, 21 is an integer multiple of both 7 and 3. In some embodiments, the duct angular spacing may be 30 degrees. An HPIN kidney angular extent in such a case could be an integer multiple of 30. For example, the HPIN kidney angular extent could be 60 degrees, 90 degrees, 120 degrees, 150 degrees, 180 degrees, 210 degrees, etc.

[0096] In some embodiments, spacing between ducts may be uniform for all ducts. By using kidney angular extents that are integral multiples of the spacing between the ducts (e.g., angular spacing of the ducts) as a duct begins to overlap with a kidney, another duct begins to leave (e.g., stop overlapping with) the kidney simultaneously. This results in a substantially constant amount of duct area of ducts of the rotor being open to (e.g., overlapping with) the kidney at substantially all instants. PX inlets may receive fluid from positive displacement compressors (e.g., have constant volumetric flow rate) and any variation in duct area open to (e.g., overlapping with) the kidney will result in flow acceleration and deceleration and corresponding unwanted pressure fluctuations. In some embodiments, PXs of the present disclosure include a duct area of rotor ducts open to the kidneys of the end covers that is substantially constant (e.g., by using kidney angular extents that are integral multiples of the angular spacing between ducts). This avoids pressure fluctuations and avoids vibrations and noise that result from pressure fluctuations.

[0097] In some embodiments, a PX may include a rotor 360 configured to receive a first fluid, receive a second fluid, and exchange pressure between the first fluid and the second fluid. In some embodiments, rotor 360 may form a plurality of ducts (e.g., ducts 310A-C of FIG. 3A and FIG. 3B).

[0098] In some embodiments, the PX may further include a first end cover 330 fluidly coupled with rotor 360. The first end cover 330 may form a first kidney 320 (e.g., fluid is to travel between a duct 310 of rotor 360 and kidney 320 of the first end cover 330). In some embodiments, a kidney angular extent 340 of first kidney 320 may be substantially an integer multiple of a duct angular spacing 350A between at least two adjacent ducts (e.g., ducts 310B and 310C) of the plurality of ducts. In some embodiments, kidney angular extent 340 is an angular distance between an opening edge 301 and a closing edge 302 of first kidney 320 and duct angular spacing 350A is an angular distance between corresponding centers of the at least two adjacent ducts (e.g., ducts 310B and 310C). In some embodiments, a kidney angular extent of a kidney being substantially an integer multiple of a duct angular spacing between at least two adjacent ducts (e.g., ducts 310B and 310C) of the plurality of ducts may include the angular extents being within + / − ten percent of being integer multiples. For example, kidney angular extent 340 would allow for a duct angular spacing between at least two adjacent ducts such that the duct area exposed to the kidney does not vary in time by more than 10%.

[0099] In some embodiments, a kidney opening edge is the edge of the kidney where a duct begins to overlap with the kidney as the rotor rotates. In some embodiments, a kidney closing edge is the edge of the kidney where a duct begins to decrease overlap and stops overlapping with the kidney as the rotor rotates. For example, in FIG. 3B, duct 310A is depicted as it begins to overlap with kidney 320 at opening edge 301 of kidney 320. In another example, in FIG. 3B, duct 310C is depicted as it begins to decrease overlap with kidney 320 at closing edge 302 of kidney 320.

[0100] In some embodiments, a kidney having an angular extent that is substantially an integer multiple of a duct angular spacing (e.g., the angular distance between two adjacent ducts) causes the duct area (e.g., of ducts of the rotor) open to the kidney to remain substantially constant as the rotor rotates leading to reduced flow ripple and pressure pulsations. In some embodiments, reducing flow ripple and pressure pulsations in PXs is beneficial for enhancing performance and efficiency. Flow ripple, characterized by variations in flow rate, and pressure pulsations, involving periodic pressure fluctuations, can lead to operational inefficiencies, equipment wear, and potential downstream issues. By minimizing these undesirable fluctuations, PXs can operate more reliably, efficiently, and with less mechanical stress, resulting in extended equipment life, energy savings, and improved system performance.

[0101] For example, in FIGS. 3A and 3B the duct area open to kidney 320 remains substantially constant even though the ducts (e.g., ducts 310A-C) may be continuously rotating past kidney 320. In conventional systems, the kidney angular extent is not substantially an integer multiple of the duct angular spacing and the duct area open to the kidney area does not remain substantially constant with time leading to high flow ripple and pressure pulsations. High flow ripple and pressure pulsations are detrimental because they reduce system efficiency, increase equipment wear, and can disrupt the stability of fluid systems, leading to operational issues and potential damage.

[0102] In some embodiments, an angular extent of a kidney may be 40 degrees and the duct angular spacing could be about 10 degrees.

[0103] In some embodiments, a kidney angular extent of a kidney being substantially an integer multiple of a duct angular spacing between at least two adjacent ducts (e.g., ducts 310B and 310C) of the plurality of ducts may include the angular extents being within + / − ten percent of being integer multiples.

[0104] In some embodiments, kidneys and duct may be a substantially similar shape (e.g., trapezoidal). In some embodiments, using kidney shapes matched with duct shape maximizes radial sealing and reduces leakage. Using kidney-shapes with the same radial extent as the ducts can enhance radial sealing and minimizing leakage. Radial sealing helps fluids or gases to remain contained. Kidney-shaped seals, with a curved and conformable design, can create secure seals. When these seals are matched to the corresponding duct or channel shapes within a system, they can enhance the sealing process by closely fitting the contours of the duct. Such a seal maximizes the contact area between the seal and the duct walls, reducing the potential for leakage and enhancing the overall integrity, reliability, and performance of the system. In some embodiments, the PX of the present disclosure has kidneys matched with ducts to maximize radial sealing lands.

[0105] In some embodiments, the rotor of the present disclosure has trapezoidal ducts instead of circular maximize the duct area density in the kidney annulus, resulting in lower max velocity in the duct and thus lower inertial losses.

[0106] FIGS. 3C-D are associated with PXs, according to some embodiments. A PX of the present disclosure may include features of one or more of FIGS. 3C-D.

[0107] FIG. 3C illustrates an end cover, according to some embodiments. In some embodiments, one or more end covers of a PX includes a seal area (e.g., spacing between a spot features of the end cover) of about a rotor duct width plus a rotor duct wall width as shown in FIG. 3C.

[0108] In some embodiments, end cover 330 includes a seal area 375 (e.g., spacing between kidneys of the end cover, spacing between spot features of the end cover, etc.) of about a rotor duct width 385 plus a rotor duct wall width 395 as shown in FIG. 3C. In some embodiments, the rotor duct wall may be the barrier between two adjacent ducts formed by the rotor.

[0109] FIG. 3D illustrates a seal plate, according to some embodiments. In some embodiments, a PX includes a passageway from LPIN aperture 384 to an LPIN center bore 382. In some embodiments, LPIN aperture 384 may be an LPIN kidney. In some embodiments, the PX of the present disclosure has LPIN as center bore fluid instead of LPOUT which reduces loss of liquid refrigerant and also reduces leakage overall.

[0110] In some embodiments, one or more end covers of a PX includes one or more pre-ramps. In some embodiments, one or more end covers of a PX includes an early open (e.g., about 5 degrees). For example, a ramp may start 5 degrees early at LPOUT.

[0111] In some embodiments, the present disclosure (e.g., PX) may have dual functions of expansion device and compressor. In some embodiments, the PX of the present disclosure has an increased duct size that enables lower RPM for the same flow rates, reducing the number of pressure cycles in a given time which reduces noise and vibrations. In some embodiments, the PX of the present disclosure has dual ramps on each kidney which enables smooth entry and exit of the fluid from the rotor, reducing shock losses. In some embodiments, the PX of the present disclosure has bearing stiffness that is increased by using shallow circumferential grooves and increased radial bearing clearances. In some embodiments, the PX of the present disclosure has axial clearance reduction to minimize leakage.

[0112] In some embodiments, the PX of the present disclosure has enhanced kidney sizes that results in multiple ducts open to the kidney at the same time reducing the pressure and flow pulsations at the ports and thereby reducing vibrations.

[0113] In some embodiments, the PX of the present disclosure has spot face addition at the HPOUT and LPOUT ports that reduces the rapidity of duct pressurization and depressurization. This reduces mixing and noise.

[0114] In some embodiments, the present disclosure includes a PX-based energy recovery device in a transcritical CO2 refrigeration system or a heat pump and its derivative applications. In some embodiments, the PX of the present disclosure reduces energy consumption in a transcritical CO2 refrigeration cycle, heat pump cycle and its derivatives.

[0115] FIG. 4 illustrates end covers 430 and 432, according to some embodiments.

[0116] In some embodiments, the first end cover 430 of FIG. 4 is a same or similar end cover as end cover 430 in FIGS. 3A-B.

[0117] In some embodiments, a PX may include a rotor configured to receive a first fluid, receive a second fluid, and exchange pressure between the first fluid and the second fluid. In some embodiments, the rotor may form a plurality of ducts (e.g., ducts 310A-C of FIG. 3A and FIG. 3B).

[0118] In some embodiments, the PX may further include a first end cover 430 fluidly coupled with the rotor, first end cover 430 forming a first kidney 420.

[0119] In some embodiments, a PX may include a second end cover 432 fluidly coupled to the rotor. In some embodiments, first end cover 430 may be fluidly couple to a first distal end of the rotor and second end cover 432 may be fluidly coupled to a second distal end of the rotor. In some embodiments, first end cover 430 and second end cover 432 substantially align allowing for precise placement of kidneys (e.g., a first kidney 420 and a second kidney 422) with relation to each other. For example, first end cover 430 and second end cover 432 may align in such a way that the first kidney 420 and second kidney 422 are offset (e.g., there is a delay angle between the first and second kidneys, a low-pressure duct opens to an HPOUT kidney on the first end cover before opening to an HPIN kidney on the second end cover, a high-pressure duct opens to an LPOUT kidney on the first end cover before opening to an LPIN kidney on the second end cover, etc.)

[0120] In some embodiments, second end cover 432 forms a second kidney 422. In some embodiments, a delay angle 470 between first kidney 420 of first end cover 430 and second kidney 422 of second end cover 432 ranges from 15 to 20 degrees. In some embodiments, delay angle 470 is an angular distance between a closing edge 403 of second kidney 422 of second end cover 432 and closing edge 401 of first kidney 420 of first end cover 430. In some embodiments, first kidney 420 includes a closing edge 402 and second kidney 422 includes a closing edge 404. In some embodiments, delay angle 470 can also be described as an angular distance between opening edge 404 of second kidney 422 of second end cover 432 and opening edge 402 of first kidney 420 of first end cover 430.

[0121] In some embodiments, first end cover 430 and second end cover 432 substantially align allowing for precise placement of kidneys (e.g., third kidney 424 and a fourth kidney 426) with relation to each other. For example, first end cover 430 and second end cover 432 may align in such a way that the third kidney 424 and fourth kidney 426 are offset (e.g., there is a delay angle between the third and fourth kidneys, a low-pressure duct opens to an HPOUT kidney on the first end cover before opening to an HPIN kidney on the second end cover, a high-pressure duct opens to an LPOUT kidney on the first end cover before opening to an LPIN kidney on the second end cover, etc.)

[0122] In some embodiments, second end cover 432 forms a third kidney 424. In some embodiments, a delay angle 460 between third kidney 424 of second end cover 432 and fourth kidney 426 of first end cover 430 ranges from 15 to 20 degrees. In some embodiments, delay angle 460 is an angular distance between an opening edge 413 of fourth kidney 426 of first end cover 430 and an opening edge 411 of third kidney 424 of second end cover 432. In some embodiments, third kidney 424 includes a closing edge 412 and fourth kidney 426 includes a closing edge 414. In some embodiments, delay angle 460 can also be described as an angular distance between closing edge 414 of fourth kidney 426 of first end cover 430 and closing edge 412 of third kidney 424 of second end cover 432.

[0123] In some embodiments, the PX of the present disclosure has a delayed opening of HPIN kidney in relation to HPOUT kidney. A PX may have reduced or no HPIN fluid exiting via HPOUT (e.g., no mixing). Some conventional systems have a rotating duct (carrying low-pressure (LP) fluid) opening to both HPIN and HPOUT kidneys at the same time which results in the duct being pressurized by fluid from both HPIN and HPOUT kidneys thereby causing large mixing and reducing the enthalpy at HPOUT. The PX of the present disclosure may reduce this mixing by opening the LP duct (e.g., a duct containing LP fluid) to HPOUT before opening to HPIN. With the delay angle (e.g., an optimum delay angle), the duct gets pressurized (e.g., pressurized purely) by HPOUT. When the duct opens to HPIN, pressure difference is small (with respect to the duct) which reduces mixing (e.g., no pressure driven jetting) and the duct contents are pushed out to HPOUT in a near plug flow manner. In some embodiments, a near plug flow manner can refer to a flow that is uniform and continuous, with minimal mixing or turbulence.

[0124] A near plug flow manner may describe the behavior of a fluid as it moves through a conduit or system (e.g., a PX). This flow pattern is characterized by minimal lateral mixing, ensuring that fluid elements move in close proximity to each other without significant dispersion. The velocity profile remains relatively uniform across the cross-section of a conduit, with orderly progression of fluid elements, and low turbulence. This controlled and organized flow is particularly useful in applications where maintaining the identity of fluid elements and minimizing mixing is important for efficient and predictable processes.

[0125] Enthalpy may refer to a fundamental thermodynamic concept representing the total energy content of a system. Enthalpy, denoted as H, comprises both the internal energy (U) of the system and the product of its pressure (P) and volume (V), as expressed by the equation H =U+PV. Enthalpy can describe how the mixing of substances within a system (e.g., a PX) impacts the overall energy content and pressure of the system. The mixing process can lead to changes in ability to absorb or reject heat, affecting the behavior of the system. In some embodiments, two fluids of different enthalpies when mixed result in an intermediate enthalpy. This mixing can be driven by the pressure dynamics within a PX.

[0126] In some embodiments, the PX of the present disclosure has a delayed opening of LPIN kidney in relation to LPOUT kidney. In some embodiments, a PX has reduced mixing. For example relatively little high pressure (HP) duct fluid may end up in LPIN. Some conventional solutions have a rotating duct carrying HP fluid opening to both LPIN and LPOUT kidneys at the same time which results in the duct fluid expanding into both LPIN and LPOUT kidneys at the same time (pressure driven jetting). To prevent this from happening, a rotor duct containing HP fluid of the present disclosure is allowed to open to (e.g., aligns with) LPOUT kidney first (e.g., with a delay angle, with an optimum delay angle) which results in the duct contents expanding into LPOUT and duct pressure equalizing. Subsequently when the duct opens to LPIN, mixing is reduced (e.g., pressure driven expansion into LPIN is avoided) and the contents are pushed out into LPOUT in a plug flow manner.

[0127] In some embodiments, the PX of the present disclosure has a delayed HPIN opening that moves the pressure and flow pulsation events to HPOUT instead of HPIN. Since the fluid is purely gas or mostly gas at HPOUT, the fluid at HPOUT has lower density and can handle the pulsations better (e.g., a given flow pulsation translates into a lower pressure pulsation) as opposed to the fluid at HPIN.

[0128] FIG. 5 illustrates an end cover, according to some embodiments.

[0129] In some embodiments, an end cover 500 (e.g., fluidly coupled with a rotor) forms a first kidney 510. In some embodiments, end cover 500 forms a second kidney 520. In some embodiments, fluid flow between ports (not shown in FIG. 5) of a PX and a rotor may be through first kidney 510 and second kidney 520. In some embodiments, a ratio of a size of the first kidney 510 to a size of the second kidney 520 ranges from 3:2 to 5:2. In some embodiments, kidney size may be a surface area of the kidney (e.g., a ratio of a surface area 512 of the first kidney 510 to a surface area 522 of the second kidney 520 ranges from 3:2 to 5:2).

[0130] In some embodiments, the PX of the present disclosure has unequal HP and LP kidney sizes. Since the density of HP fluid is many times higher than the density of LP fluid, pressure losses due to inertia (caused by the duct fluid being accelerated and decelerated continuously) are higher on the HP side than on the LP side. This results in imbalanced rotor thrust. By sizing the HP kidneys and LP kidneys differently, inertial DP losses on both HP and LP kidneys can be balanced better resulting in reduced rotor thrust loads.

[0131] In some embodiments, first end cover 500 includes an end cover surface 502 (e.g., that faces the rotor). In some embodiments, end cover surface 502 forms a buffer chamber 560 disposed in a delay region 580 of end cover 500. A buffer chamber can be a recess formed on the surface of an end cover. In some embodiments, the buffer can face the rotor or another moving component in the PX. The primary function of a buffer chamber can be to serve as a space or cavity designed to stabilize fluid flow and minimize pressure fluctuations, particularly in applications where controlled flow is essential (e.g., PXs). Buffer chambers can also equalize pressure differentials, reduce turbulence, and can assist in heat dissipation. In some embodiments, buffer chambers can separate and capture particulate matter or contaminants, ensuring cleaner downstream fluid or gas.

[0132] In some embodiments, delay region 580 is a region between an opening edge 530 of first kidney 510 of the first end cover and an opening edge 530 of first kidney 510 of the second end cover. In some embodiments, a kidney opening edge is the edge of the kidney where a duct begins to overlap with the kidney as the rotor rotates. In some embodiments, a kidney closing edge is the edge of the kidney where a duct begins to decrease overlap and stops overlapping with the kidney as the rotor rotates. For example, arrow 590 shows the rotation direction of the rotor. In some embodiments, ducts will pass over first kidney 510, second kidney 520, and buffer chamber 560 in the direction indicated by arrow 590.

[0133] In some embodiments, a spacing between the buffer chamber and the kidneys is at least as wide as one duct (e.g., duct 550). This may prevent HPIN fluid (or other fluids in alternative embodiments) from entering the buffer chamber.

[0134] In some embodiments, buffer chamber 560 is a substantially similar shape (e.g., trapezoidal) as first kidney 510 and has an angular extent 562 substantially equal to an angular extent of a rotor duct of the rotor. In some embodiments, buffer chamber 560 is a substantially similar shape (e.g., trapezoidal) as first kidney 510 and may have an angular extent 562 that is substantially double angular extent 592 of the rotor duct of the rotor. In some embodiments, buffer chamber 560 may be a blind recess. In some embodiments, buffer chamber 560 may minimize pressure fluctuations in the PX.

[0135] In some embodiments, first kidney 510 may be an HPIN kidney and second kidney 520 may be an LPOUT kidney. In some embodiments, first kidney 510 may be an HPOUT kidney and second kidney 520 may be an LPIN kidney. Conventional solutions (e.g., using high-pressure and low-pressure kidneys of the same size) cause pressure losses. Because the density of the high-pressure fluid is many times higher than the density of low-pressure fluid the high-pressure fluid has higher inertia (e.g., caused by the duct fluid being accelerated and decelerated continuously). This results in imbalanced rotor thrust in conventional solutions. In some embodiments, using unequal kidney sizes between high-pressure and low-pressure kidneys (e.g., By sizing the HP kidneys larger than the LP kidneys) causes inertial differential pressure losses for both high-pressure and low-pressure kidneys to be more balanced resulting in reduced rotor thrust loads.

[0136] In some embodiments, fluid flow between ports of the PX and the rotor is through first kidney 510 and second kidney 520. In some embodiments, a ratio of a size of first kidney 510 to a size of second kidney 520 ranges from about 3:2 to about 5:2.

[0137] FIG. 6 illustrates an end cover 600 including a buffer chamber 670, according to some embodiments.

[0138] In some embodiments, a PX includes a rotor configured to receive a first fluid, receive a second fluid, and exchange pressure between the first fluid and the second fluid. In some embodiments, the rotor forms a plurality of ducts. In some embodiments, the PX includes a first end cover 600 fluidly coupled with the rotor, first end cover 600 forming a first kidney 620.

[0139] In some embodiments, first end cover 600 forms a second kidney 622, first end cover 600 including a first end cover surface 602 that faces the rotor, first end cover surface 602 forming a buffer chamber 670 disposed in a delay region 680 of first end cover 600. In some embodiments, delay region 680 is a region between a closing edge 660 of buffer chamber 670 and an opening edge 630 of first kidney 620. In some embodiments, delay region 680 is a region between the opening edge 630 of first kidney 620 on first end cover 600 and an opening edge of a second kidney on a second end cover. The opening edge 630 of first kidney 620 on first end cover 600 is represented by the dotted line 660 in FIG. 6.

[0140] In some embodiments, a kidney opening edge is the edge of the kidney where a duct begins to overlap with the kidney as the rotor rotates. In some embodiments, a kidney closing edge is the edge of the kidney where a duct begins to decrease overlap and stops overlapping with the kidney as the rotor rotates. For example, arrow 690 shows the rotation direction of the rotor. In some embodiments, ducts will pass over first kidney 620, second kidney 622, and buffer chamber 670 in the direction indicated by arrow 690.

[0141] In some embodiments, a buffer chamber opening edge is the edge of the buffer chamber where a duct begins to overlap with the buffer chamber as the rotor rotates. In some embodiments, a buffer chamber closing edge is the edge of the buffer chamber where a duct begins to decrease overlap and stops overlapping with the buffer chamber as the rotor rotates.

[0142] In some embodiments, buffer chamber 670 is a substantially similar shape (e.g., trapezoidal) as first kidney 620 and has an angular extent 682 substantially equal to an angular extent of the rotor duct of the rotor. In some embodiments, fluid flow between ports of the PX and the rotor is through first kidney 620 and second kidney 622. In some embodiments, a ratio of a size of first kidney 620 to a size of second kidney 622 ranges from about 3:2 to about 5:2.

[0143] In some embodiments, a spacing between the buffer chamber and the kidneys is at least as wide as one duct (e.g., duct 650). This may prevent HPIN fluid (or other fluids in alternative embodiments) from entering the buffer chamber.

[0144] In some embodiments, line 660 indicates where an HPOUT kidney opens on a second end cover. See FIGS. 7A-B and 8A-B for a more detailed description.

[0145] FIG. 7A illustrates a PX having a rotor and end covers forming a buffer chamber, according to some embodiments.

[0146] In some embodiments, PX includes a rotor 730A configured to receive a first fluid, receive a second fluid, and exchange pressure between the first fluid and the second fluid. In some embodiments, rotor 730A forms a plurality of ducts (e.g., LP duct 760A). In some embodiments, HP duct refers to a duct containing HP fluid. In some embodiments, the PX includes a first end cover 710A fluidly coupled with rotor 730A, first end cover 710A forming a first kidney 750A. In some embodiments, second end cover 712A forms a second kidney HPOUT kidney 740A. In some embodiments, first end cover 710A includes a first end cover surface 770A that faces rotor 730A, first end cover surface 770A forming a buffer chamber 720A disposed in a delay region (e.g., upstream of HPIN kidney 750A) of first end cover 710A. In some embodiments, the delay region may be a region between an opening edge of the second kidney 740A (shown by the dotted line 761A) on the second end cover and an opening edge of first kidney 750A.

[0147] In some embodiments, a PX 700A may include a buffer chamber 720A on an HPIN end cover 710A upstream of HPIN kidney 750A in the delay area (e.g., between an opening edge of HPIN kidney 750A and the opening edge of the HPOUT kidney 740A). In some embodiments, buffer chamber 720A may be a blind recess having similar shape and radial extent as the rotor ducts. In some embodiments, buffer chamber 720A may be machined into HPIN end cover 710A in the delay region. In some embodiments, the starting angle of the blind recess (e.g., buffer chamber 720A) matches the starting angle of HPOUT kidney 740A (e.g., buffer chamber 720A and HPOUT kidney are substantially aligned). Line 761A shows the matching starting angles of buffer chamber 720A and HPOUT kidney 740A. In some embodiments, the ending angle of the blind recess (e.g., buffer chamber 720A) may be set to prevent any communication with HPIN kidney 750A through the ducts. In some embodiments, the blind recess may store a “buffer” of HPOUT fluid continually.

[0148] In some embodiments, PX 700A, includes a second end cover 712A fluidly coupled to rotor 730A. In some embodiments, second end cover 712A forms a third kidney 740A. In some embodiments, when a first duct (e.g., partly pressurized duct 764A) of the plurality of ducts substantially aligns with buffer chamber 720A, third kidney 740A substantially aligns with the first duct (e.g., as shown by line 761A).

[0149] In some embodiments, third kidney 740A may be an HPOUT kidney and the first and second ducts may be low-pressure ducts (e.g., ducts filled with low-pressure fluid). In some embodiments, first kidney 750A may be an HPIN kidney, and the first duct (e.g., partly pressurized duct 764A) substantially aligns with first kidney 750A after aligning with buffer chamber 720A. For example, partially pressurized duct 764A will only align with first kidney 750A after rotating past buffer chamber 720A.

[0150] In some embodiments, a kidney angular extent of the first kidney 750A may be substantially an integer multiple of a duct angular extent between at least two adjacent ducts (e.g., LP duct 760A and partly pressurized duct 764A) of the plurality of ducts. In some embodiments, LP duct refers to a duct containing LP fluid. In some embodiments, the kidney angular extent is an angular distance between an opening edge and a closing edge of first kidney 750A and the duct angular extent is an angular distance between corresponding centers of the at least two adjacent ducts.

[0151] In some embodiments, when a duct (e.g., LP duct 760A) carrying low-pressure fluid opens to the HPOUT kidney 740A, the duct may be simultaneously open to buffer chamber 720A, causing the LP duct 760A to be pressurized from a first distal end and a second distal end of the duct simultaneously. In some embodiments, a duct getting pressurized simultaneously at the first distal end (e.g., by HPOUT kidney 740A) and the second distal end (e.g., by buffer chamber 720A) may cause the duct to pressurize faster and may also dampen the amplitude of pressure waves in the duct reducing jetting (e.g., when open to HPIN kidney 750A) and reducing mixing.

[0152] In some embodiments, buffer chamber 720A is a substantially similar shape (e.g., trapezoidal) as first kidney 750A and has an angular extent substantially equal to an angular extent of a rotor duct (e.g., partly pressurized rotor duct 764A). In some embodiments, fluid flow between ports of the PX 700A and rotor 730A is through first kidney 750A and a third kidney formed by end cover 710A. In some embodiments, a ratio of a size of first kidney 750A to a size of the second kidney ranges from 3:2 to 5:2.

[0153] In some embodiments, a spacing between the buffer chamber and the kidneys is at least as wide as one duct. This may prevent HPIN fluid (or other fluids in alternative embodiments) from entering the buffer chamber.

[0154] FIG. 7B illustrates a PX having a rotor and end covers forming a buffer chamber, according to some embodiments.

[0155] In some embodiments, a PX 700B includes a rotor 730B configured to receive a first fluid, receive a second fluid, and exchange pressure between the first fluid and the second fluid. In some embodiments, rotor 730B includes a plurality of ducts (e.g., LP duct 760B). In some embodiments, PX 700B includes a first end cover 710B fluidly coupled with rotor 730B. In some embodiments, first end cover 710B includes a first end cover surface 770B that faces rotor 730B. In some embodiments, first end cover surface 770B forms a buffer chamber 720B disposed in a delay region (see FIGS. 5 and 6) of first end cover 710B. In some embodiments, first end cover 710B forms a first kidney 750B. In some embodiments, second end cover 712B forms a second kidney 740B. In some embodiments, the delay region is a region between an opening edge of first kidney 750B on the end cover 710B and the opening edge of first kidney 740B on the second end cover 712B.

[0156] In some embodiments, PX 700B includes a second end cover 712B fluidly coupled to rotor 730B. In some embodiments, second end cover 712B forms a third kidney 740B. In some embodiments, a first duct and a second duct (e.g., partly pressurized ducts 764B) of the plurality of ducts substantially align with buffer chamber 720B simultaneously (e.g., as shown by lines 761B and 762B) while third kidney 740B substantially aligns with the first duct (e.g., as shown by line 761B).

[0157] In some embodiments, third kidney 740B may be an HPOUT kidney and the first and second ducts may be low-pressure ducts (e.g., ducts filled with low-pressure fluid). In some embodiments, first kidney 750B may be an HPIN kidney, and the first duct substantially aligns with first kidney 750B after aligning with buffer chamber 720B. For example, partially pressurized ducts 764B will only align with first kidney 750B after rotating past buffer chamber 720B.

[0158] In some embodiments, a kidney angular extent of the first kidney 750B may be substantially an integer multiple of a duct angular extent between at least two adjacent ducts (e.g., partly pressurized ducts 764B) of the plurality of ducts. In some embodiments, the kidney angular extent is an angular distance between an opening edge and a closing edge of first kidney 750B and the duct angular extent is an angular distance between corresponding centers of the at least two adjacent ducts.

[0159] In some embodiments, buffer chamber 720B is a substantially similar shape (e.g., trapezoidal) as first kidney 750B and has an angular extent substantially double the angular extent of rotor duct 764B. In some embodiments, fluid flow between ports of the PX 700B and rotor 730B is through first kidney 750B and the third kidney formed by end cover 710B. In some embodiments, a ratio of a size of first kidney 750B to a size of the second kidney ranges from 3:2 to 5:2.

[0160] In some embodiments, a spacing between the buffer chamber and the kidneys is at least as wide as one duct. This may prevent HPIN fluid (or other fluids in alternative embodiments) from entering the buffer chamber.

[0161] FIG. 8A illustrates a PX having a rotor and end covers forming a buffer chamber, according to some embodiments.

[0162] In some embodiments, a buffer chamber may be implemented upstream of an LPIN kidney in the delay area (see FIGS. 5 and 6). This effectively increases the delay angle, enabling the high-pressure duct to begin depressurizing before it opens to LPOUT kidney.

[0163] In some embodiments, PX 800A includes a rotor 830A configured to receive a first fluid, receive a second fluid, and exchange pressure between the first fluid and the second fluid. In some embodiments, rotor 830A forms a plurality of ducts (e.g., HP duct 860A, partly depressurized duct 864A, etc.). In some embodiments, HP duct refers to a duct containing HP fluid. In some embodiments, PX 800A includes a first end cover 810A fluidly coupled with rotor 830A. In some embodiments, first end cover 810A forms a first kidney 850A. In some embodiments, first kidney 850A may be an LPIN kidney. In some embodiments, first end cover 810A forms a second kidney (not shown in FIG. 8A). In some embodiments, first end cover 810A includes a first end cover surface 870A that faces rotor 830A. In some embodiments, first end cover surface 870A forms a buffer chamber 820A disposed in a delay region (e.g., upstream of HPIN kidney 850A) of first end cover 810A. In some embodiments, the delay region may be a region between the opening edge of the first kidney 850A and an opening edge (e.g., line 861A) of first kidney 840A. In some embodiments, upstream indicated a direction that is contrary to the direction of rotation of the rotor.

[0164] In some embodiments, PX 800A may include a buffer chamber 820A on an LPIN end cover 810A upstream of LPIN kidney 850A in the delay area (e.g., between an opening edge of LPIN kidney 850A and an opening edge of the LPOUT kidney 840A). In some embodiments, buffer chamber 820A may be a blind recess having similar shape and radial extent as the kidneys. In some embodiments, buffer chamber 820A may be machined into LPIN end cover 810A in the delay region. In some embodiments, the starting angle of the blind recess (e.g., buffer chamber 820A) matches the starting angle of LPOUT kidney 840A (e.g., buffer chamber 820A and LPOUT kidney are substantially aligned). Line 861A shows the matching starting angles of buffer chamber 820A and LPOUT kidney 840A. In some embodiments, the ending angle of the blind recess (e.g., buffer chamber 820A) may be set to prevent any communication with LPIN kidney 850A through the ducts. In some embodiments, the blind recess may store a “buffer” of LPOUT fluid continually.

[0165] In some embodiments, PX 800A, includes a second end cover 812A fluidly coupled to rotor 830A. In some embodiments, second end cover 812A forms a third kidney 840A. In some embodiments, when a first duct (e.g., partly depressurized duct 864A) of the plurality of ducts substantially aligns with buffer chamber 820A, third kidney 840A substantially aligns with the first duct (e.g., as shown by line 861A).

[0166] In some embodiments, third kidney 840A may be an LPOUT kidney and the first and second ducts may be high pressure ducts (e.g., ducts filled with high-pressure fluid). In some embodiments, first kidney 850A may be an LPIN kidney, and the first duct substantially aligns with first kidney 850A after aligning with buffer chamber 820A. For example, partially pressurized duct 864A will only align with first kidney 850A after rotating past buffer chamber 820A.

[0167] In some embodiments, a kidney angular extent of the first kidney 850A may be substantially an integer multiple of a duct angular extent between at least two adjacent ducts (e.g., LP duct 860A and partly pressurized duct 864A) of the plurality of ducts. In some embodiments, the kidney angular extent is an angular distance between an opening edge and a closing edge of first kidney 850A and the duct angular extent is an angular distance between corresponding centers of the at least two adjacent ducts.

[0168] In some embodiments, when a duct (e.g., HP duct 860A) carrying high-pressure fluid opens to the LPOUT kidney 840A, the duct may be simultaneously open to buffer chamber 820A, causing the HP duct 860A to be depressurized from a first distal end and a second distal end of the duct simultaneously. In some embodiments, a duct being depressurized simultaneously at the first distal end (e.g., by LPOUT kidney 840A) and the second distal end (e.g., by buffer chamber 820A) may cause the duct to depressurize faster and may also dampen the amplitude of pressure waves in the duct reducing jetting (e.g., when open to LPIN kidney 850A) and reducing mixing.

[0169] In some embodiments, buffer chamber 820A is a substantially similar shape (e.g., trapezoidal) as first kidney 850A and has an angular extent substantially equal to an angular extent of rotor duct 860A In some embodiments, fluid flow between ports of the PX 800A and rotor 830A is through first kidney 850A and a third kidney formed by end cover 810A. In some embodiments, a ratio of a size of first kidney 850A to a size of the second kidney ranges from 3:2 to 5:2.

[0170] In some embodiments, a spacing between the buffer chamber and the kidneys is at least as wide as one duct. This may prevent LPIN fluid (or other fluids in alternative embodiments) from entering the buffer chamber.

[0171] FIG. 8B illustrates a PX having a rotor and end covers forming a buffer chamber, according to some embodiments.

[0172] In some embodiments, a PX 800B includes a rotor 830B configured to receive a first fluid, receive a second fluid, and exchange pressure between the first fluid and the second fluid. In some embodiments, rotor 830B includes a plurality of ducts (e.g., HP duct 860B, partly depressurized ducts 864B, etc.). In some embodiments, PX 800B includes a first end cover 810B fluidly coupled with rotor 830B. In some embodiments, first end cover 810B includes a first end cover surface 870B that faces rotor 830B. In some embodiments, first end cover surface 870B forms a buffer chamber 820B disposed in a delay region (see FIGS. 5 and 6) of first end cover 810B. In some embodiments, first end cover 810B forms a first kidney 850B and a second kidney (not shown in FIG. 8B). In some embodiments, the delay region is a region between an opening edge of the first kidney 840B and an opening edge of first kidney 850B.

[0173] In some embodiments, PX 800B includes a second end cover 812B fluidly coupled to rotor 830B. In some embodiments, second end cover 812B forms a third kidney 840B. In some embodiments, a first duct and a second duct (e.g., partly pressurized ducts 864B) of the plurality of ducts substantially align with buffer chamber 820B simultaneously (e.g., as shown by lines 861B and 862B) while third kidney 840B substantially aligns with the first duct (e.g., as shown by line 861B).

[0174] In some embodiments, third kidney 840B may be an LPOUT kidney and the first and second ducts may be high pressure ducts (e.g., ducts filled with high-pressure fluid). In some embodiments, first kidney 850B may be an LPIN kidney, and the first duct substantially aligns with first kidney 850B after aligning with buffer chamber 820B. For example, partially pressurized ducts 864B will only align with first kidney 850B after rotating past buffer chamber 820B.

[0175] In some embodiments, a kidney angular extent of the first kidney 850B may be substantially an integer multiple of a duct angular extent between at least two adjacent ducts (e.g., partly pressurized ducts 864B) of the plurality of ducts. In some embodiments, the kidney angular extent is an angular distance between an opening edge and a closing edge of first kidney 850B and the duct angular extent is an angular distance between corresponding centers of the at least two adjacent ducts.

[0176] In some embodiments, buffer chamber 820B is a substantially similar shape (e.g., trapezoidal) as first kidney 850B and has an angular extent substantially double the angular extent of rotor duct 860B. In some embodiments, fluid flow between ports of the PX 800B and rotor 830B is through first kidney 850B and a third kidney formed by end cover 810B. In some embodiments, a ratio of a size of first kidney 850B to a size of the second kidney ranges from 3:2 to 5:2.

[0177] In some embodiments, a spacing between the buffer chamber and the kidneys is at least as wide as one duct. This may prevent LPIN fluid (or other fluids in alternative embodiments) from entering the buffer chamber.

[0178] FIG. 9 illustrates a rotor forming ducts, according to some embodiments.

[0179] In some embodiments, a rotor 900 may be configured to receive a first fluid, receive a second fluid, and exchange pressure between the first fluid and the second fluid. In some embodiments, rotor 900 forms a plurality of ducts (e.g., inner ducts 910, outer ducts 920, etc.).

[0180] In some embodiments, rotor 900 forms the ducts in a plurality of concentric rows (e.g., inner row 912, outer row 922, etc.). For example, inner ducts 910 form inner row 912 and outer ducts 920 form outer row 922. In some embodiments, inner row 912 and outer row 922 are concentric rows. In some embodiments, concentric rows may refer to a pattern in which multiple rows of objects (e.g., ducts) are arranged in a circular manner, with each row positioned at a distance from the center, creating a series of circles or rings. In some embodiments, the rows may be staggered. For example, line 930 and line 932 show how ducts of inner ring 912 and ducts of the outer ring 922 may be staggered. In some embodiments, the use of staggered rows may reduce the total amount of duct volume that pressurizes and / or depressurizes at a time which reduces noise and vibration of the PX.

[0181] In some embodiments, using multiple rows of staggered ducts may reduce pressure pulsations at an HPOUT port and HPOUT kidney. For example, when a low-pressure duct (e.g., filled with LPIN fluid) opens to the HPOUT kidney, a jet of fluid rushes into the low-pressure duct due to the pressure differential, resulting in a short near-instantaneous flow reversal at the HPOUT port. This flow reversal causes an instantaneous pressure drop at the HPOUT port, resulting in pressure pulsations and vibrations. By increasing the number of ducts and reducing the size of each duct (total duct volume remains constant), the magnitude of flow reversal and duration is kept small. This results in lower pressure pulsations and corresponding vibrations at the HPOUT port.

[0182] In some embodiments, duct size may be increased to enable higher flow rates with lower RPMs, reducing the number of pressure cycles in a given time, and thereby reducing noise and vibrations. In some embodiments, larger kidney sizes may result in multiple ducts being open to the kidney (e.g., overlapping the kidney) simultaneously reducing the pressure and flow pulsations at the ports and thereby reducing vibrations. In some embodiments, trapezoidal ducts may be used (e.g., instead of circular ducts) to maximize the duct area density in the kidney annulus, resulting in lower max velocity in the duct and thus lower inertial losses.

[0183] In some embodiments, using an odd number of ducts (e.g., instead of an even number) enables temporal separation of pressurization and depressurization events. This results in reduced noise & vibrations.

[0184] FIG. 10 illustrates a pre-pressurization hole, according to some embodiments.

[0185] In some embodiments, pre-pressurizing a low-pressure duct before the low-pressure duct opens to an HPOUT kidney 1010 can be accomplished using a kidney pre-pressurization opening 1020, a pre-pressurization conduit 1030, and a pre-pressurization opening 1000 connecting the HPOUT kidney 1010 to the low-pressure duct when upstream of the HPOUT kidney 1010. This allows for pre-pressurization of the duct and allows for faster stabilization of pressure when the duct eventually opens to HPOUT kidney 1010. In some embodiments, the conduit 1030 and a pre-pressurization opening 1000 are disposed in end cover 1040. In some embodiments, pre-pressurization opening 1000 faces the rotor (e.g., fluidly coupled to end cover 1040. Arrow 1070 indicates the rotation direction of the rotor (e.g., fluidly connected to the end cover).

[0186] FIG. 11A illustrates a spot face according to certain embodiments.

[0187] In some embodiments, an HP kidney may have a spotface that is deeper than conventional spotfaces. For example, a PX may include rotor 1110A forming ducts. The PX may further include an end cover 1100A including an HP kidney 1120A. HP kidney 1120A includes a spotface 1190A that is deeper than conventional spotfaces. In some embodiments, a deeper spotface addition may be at the HPOUT or LPOUT ports and may reduce the rapidity of duct pressurization and depressurization. This reduces mixing and noise. Compressible fluids such as CO2 can choke when leaking through the spot face from HP Kidney (e.g., HP kidney 1120A) into an LP duct. This effectively limits the rate of the LP duct pressurization. An alternative spot face design (e.g., deeper spot faces) allows for faster pressurization even when the pressure ratio exceeds the critical pressure ratio for choking.

[0188] Conventional PXs may include an HP kidney having a spotface that is shallow. For example, a conventional PX may include a rotor forming ducts. The conventional PX may further include an end cover including an HP kidney. The HP kidney can include a spotface that is shallow. A shallow spotface can reduce the rapidity of duct pressurization and depressurization. This reduces mixing and noise. Compressible fluids such as CO2 choke when leaking through the spot face from HP Kidney (e.g., HP kidney 1120A) into an LP duct. This effectively limits the rate of the LP duct pressurization.

[0189] 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 order to 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.

[0190] 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.

[0191] 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.

[0192] 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 reading and 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.

Examples

Embodiment Construction

[0020]Embodiments described herein are related to transcritical refrigeration PXs.

[0021]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 hydraulic fracturing (e.g., fracking or fracing) systems, desalinization systems, refrigeration systems, heat pump systems, energy generation systems, mud pumping systems, slurry pumping systems, industrial fluid systems, waste fluid systems, fluid transportation systems, etc. Pumps or compressors may be used to increase pressure of fluids of such systems.

[0022]Conventionally, 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 (CO...

RELATED APPLICATIONS

[0001] This is a national stage application under 35 U.S.C. 371 of International Application PCT / US23 / 81213, filed Nov. 27, 2023, which claims benefit to U.S. Provisional Patent Application No. 63 / 428,260, filed Nov. 28, 2022, the contents of each are incorporated by reference in their entirety herein.TECHNICAL FIELD

[0002] The present disclosure relates to pressure exchangers (PXs), and, more particularly, PXs used in refrigeration systems.BACKGROUND

[0003] Systems use fluids at different pressures. Systems use components to increase pressure of fluid.BRIEF DESCRIPTION OF THE DRAWINGS

[0004] The present disclosure is illustrated by way of example, and not by way of limitation in the figures of the accompanying drawings.

[0005] FIGS. 1A-D illustrate schematic diagrams of fluid handling systems including hydraulic energy transfer systems, according to certain embodiments.

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

[0007] FIGS. 3A-B illustrate PXs including end covers forming kidneys and rotors forming ducts, according to some embodiments.

[0008] FIG. 3C illustrates an end cover, according to some embodiments.

[0009] FIG. 3D illustrates a seal plate, according to some embodiments.

[0010] FIG. 4 illustrates end covers, according to some embodiments.

[0011] FIG. 5 illustrates an end cover, according to some embodiments.

[0012] FIG. 6 illustrates an end cover including a buffer chamber, according to some embodiments.

[0013] FIG. 7A illustrates a PX having a rotor and end covers, according to some embodiments.

[0014] FIG. 7B illustrates a PX having a rotor and end covers, according to some embodiments.

[0015] FIG. 8A illustrates a PX having a rotor and end covers, according to some embodiments.

[0016] FIG. 8B illustrates a PX having a rotor and end covers, according to some embodiments.

[0017] FIG. 9 illustrates a rotor forming ducts, according to some embodiments.

[0018] FIG. 10 illustrates an end cover forming a pre-pressurization hole, according to some embodiments.

[0019] FIG. 11 illustrates a spot face of an end cover, according to certain embodiments.DETAILED DESCRIPTION OF EMBODIMENTS

[0020] Embodiments described herein are related to transcritical refrigeration PXs.

[0021] 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 hydraulic fracturing (e.g., fracking or fracing) systems, desalinization systems, refrigeration systems, heat pump systems, energy generation systems, mud pumping systems, slurry pumping systems, industrial fluid systems, waste fluid systems, fluid transportation systems, etc. Pumps or compressors may be used to increase pressure of fluids of such systems.

[0022] Conventionally, 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, capillaries or orifices. 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). In some embodiments, the present disclosure is directed to a high performance transcritical carbon dioxide (CO2) PX design. The PX of the present disclosure may be used for transcritical CO2 refrigeration and / or heat pump applications.

[0023] The systems, devices, and methods of the present disclosure provide PXs for use in systems (e.g., fluid handling systems, heat transfer systems, refrigeration systems, heat pump systems, cooling systems, heating systems, etc.). 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 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). The PX may be a rotary PX that exchanges pressure energy between two streams of a transcritical gas (e.g., CO2 in either liquid, gas, or a mixture of the two phases).

[0024] Some systems (e.g., PX based heat transfer systems) may have high vibration levels at input and / or output ports (e.g., of the PX) that exceed standards (e.g., American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) standards) for refrigeration compressors. Some systems may also have high noise levels that exceed the limits adhered to by most of the compressor equipment manufacturers. Some systems (e.g., PX based systems) may not reduce energy consumption effectively due to various losses expansion losses, mixing losses, internal leakage losses and pressure losses. Some systems (e.g., PX based systems) do not mitigate mixing effectively resulting in increased enthalpy dilution at high pressure out kidneys (HPOUT kidneys) and diminished liquid fraction at low pressure out kidneys (LPOUT kidneys) diminishing PX energy savings. Some systems (e.g., PX based systems) may have high pressure drop across the PX (especially at higher flows and RPMs) resulting in increased compressor work and diminished energy savings. Some systems (e.g., PX based systems) may have high leakage through the PX bearings causing decreased refrigerant flow through the rotor decreasing energy recovery. Some systems (e.g., PX based systems) may have higher risk of cavitation and can diminish bearing stiffness / load capability.

[0025] Systems of the present disclosure may solve one or more of these and other problems. Systems of the present disclosure reduce wear on components (e.g., pumps, compressors) compared to conventional systems. Systems of the present disclosure reduce mixing in the transcritical CO2 PX resulting in reduced enthalpy dilution at HPOUT and enhanced liquid fraction at LPOUT, enhancing PX energy savings compared to conventional systems. Systems of the present disclosure reduce pressure drop across the PX (especially at higher flows and RPMs) resulting in reduced booster work and enhanced energy savings compared to conventional systems. Systems of the present disclosure reduce leakage through the PX bearings enabling increased refrigerant flow through the rotor, thereby increasing energy recovery compared to conventional systems (e.g., conventional PX based systems). The present disclosure can reduce the risk of cavitation and can enhance bearing stiffness / load capability compared to conventional systems (e.g., conventional PX based systems). Using end covers with reduced thickness and eliminating the carrier plate results in a shorter and stiffer drive train compared to conventional systems (e.g., conventional PX based systems).

[0026] In some embodiments, a PX includes one or more of the features described in one or more of FIGS. 3A-11.

[0027] In some embodiments, a PX includes a rotor configured to receive a first fluid, receive a second fluid, and exchange pressure between the first fluid and the second fluid. The rotor forms a plurality of ducts. The PX further includes a first end cover fluidly coupled with the rotor, the first end cover forming a first kidney, where a kidney angular extent of the first kidney is substantially an integer multiple of a duct angular spacing between at least two adjacent ducts of the plurality of ducts. In some embodiments, the kidney angular extent is an angular distance between an opening edge and a closing edge of the first kidney and a duct angular extent is an angular distance between corresponding centers of the at least two adjacent ducts.

[0028] In some embodiments, the PX includes a second end cover that forms a second kidney, where a delay angle between the first kidney and the second kidney ranges from 15 to 20 degrees. In some embodiments, the delay angle is an angular distance between a closing edge of the second kidney and a closing edge of the first kidney. In some embodiments, a similar delayed opening may be present on the first kidney in the second end cover. In some embodiments, a similar delayed opening may be present a third kidney formed by the first end cover and a fourth kidney formed by the second end.

[0029] In some embodiments, the rotor forms the ducts in a plurality of concentric rows. The ducts in two rows being staggered.

[0030] In some embodiments, the PX includes a second end cover, where the second end cover forms a second kidney. In some embodiments, the second kidney may have a delayed opening with respect to the first kidney formed by the first end cover. The first end cover includes a first end cover surface that faces the rotor, the first end cover surface forming a buffer chamber disposed in a delay region of the first end cover. In some embodiments, the delay region is a region between an opening edge of the second kidney and an opening edge of the first kidney.

[0031] In some embodiments, the first end cover forms a third kidney. In some embodiments, fluid flow between ports of the PX and the rotor is through the first kidney and the third kidney. In some embodiments, a ratio of a size of the first kidney to a size of the third kidney ranges from 3:2 to 5:2.

[0032] In some embodiments, a PX includes a rotor configured to receive a first fluid, receive a second fluid, and exchange pressure between the first fluid and the second fluid. In some embodiments, the rotor forms a plurality of ducts. The pressure exchanger further includes a first end cover fluidly coupled with the rotor, the first end cover comprising a first end cover surface that faces the rotor. The first end cover surface forms a buffer chamber disposed in the delay region of the first end cover. In some embodiments, the PX includes a second end cover forming a second kidney, where the delay region is a region between an opening edge of the second kidney and an opening edge of the first kidney.

[0033] In some embodiments, the PX further includes a second end cover fluidly coupled to the rotor, the second end cover forming a third kidney. In some embodiments, when a first duct of the plurality of ducts substantially aligns with the buffer chamber, the third kidney substantially aligns with the first duct.

[0034] In some embodiments, the first duct and a second duct of the plurality of ducts substantially align with the buffer chamber simultaneously while the third kidney substantially aligns with the first duct.

[0035] In some embodiments, the third kidney is a high pressure out (HPOUT) kidney and the first and second ducts are low-pressure ducts.

[0036] In some embodiments, the first kidney is a high pressure in (HPIN) kidney, and the first duct substantially aligns with the first kidney after aligning with the buffer chamber.

[0037] In some embodiments, the third kidney is a low pressure out (LPOUT) kidney and the first and second ducts are high pressure ducts.

[0038] In some embodiments, the first kidney is a low pressure in (LPIN) kidney, and the first duct substantially aligns with the first kidney after aligning with the buffer chamber.

[0039] In some embodiments, a kidney angular extent of the first kidney is substantially an integer multiple of a duct angular spacing between at least two adjacent ducts of the plurality of ducts. In some embodiments, the kidney angular extent is an angular distance between an opening edge and a closing edge of the first kidney and the duct angular extent is an angular distance between corresponding centers of the at least two adjacent ducts.

[0040] In some embodiments, the buffer chamber is a substantially similar shape as the first kidney and has an angular extent substantially equal to or substantially double an angular extent of a rotor duct of the plurality of rotor ducts.

[0041] In some embodiments, the first end cover forms a third kidney. In some embodiments, fluid flow between ports of the PX and the rotor is through the first kidney and the third kidney. In some embodiments, a ratio of a size of the first kidney to a size of the third kidney ranges from 3:2 to 5:2.

[0042] In some embodiments, a PX includes a rotor configured to receive a first fluid, receive a second fluid, and exchange pressure between the first fluid and the second fluid. The PX further includes a first end cover fluidly coupled with the rotor, the first end cover forming a first kidney and a second kidney. In some embodiments, fluid flow between ports of the PX and the rotor is through the first kidney and the second kidney. In some embodiments, a ratio of a size of the first kidney to a size of the second kidney ranges from 3:2 to 5:2.

[0043] In some embodiments, the first kidney is a high-pressure kidney, and the second kidney is a low-pressure kidney.

[0044] In some embodiments, the PX further includes a second end cover fluidly coupled with the rotor, the second end cover forming a third kidney and a fourth kidney. In some embodiments, fluid flow between ports of the PX and the rotor is through the third kidney and the fourth kidney. In some embodiments, a ratio of a size of the third kidney to a size of the fourth kidney ranges from 3:2 to 5:2.

[0045] In some embodiments, the third kidney is a high-pressure kidney, and the fourth kidney is a low-pressure kidney.

[0046] In some embodiments, the rotor forms a plurality of ducts. In some embodiments, a kidney angular extent of the first kidney is substantially an integer multiple of a duct angular extent between at least two adjacent ducts of the plurality of ducts. In some embodiments, the rotor forms a plurality of ducts. In some embodiments, a kidney angular extent of the first kidney is substantially an integer multiple of the angular spacing between at least two adjacent ducts of the plurality of ducts. In some embodiments, the kidney angular extent is an angular distance between an opening edge and a closing edge of the first kidney and the duct angular extent is an angular distance between corresponding centers of the at least two adjacent ducts.

[0047] 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. For example, use of a PX 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 system. Systems of the present disclosure reduce mixing in the transcritical CO2 PX resulting in reduced enthalpy dilution at HPOUT and enhanced liquid fraction at LPOUT enhancing PX energy savings compared to conventional systems. Systems of the present disclosure reduce pressure drop across the PX (especially at higher flows and RPMs) resulting in reduced booster work and enhanced energy savings compared to conventional systems. Systems of the present disclosure reduce leakage through the PX bearings enabling increased refrigerant flow through the rotor increasing energy recovery compared to conventional systems. The present disclosure can reduce the risk of cavitation and can enhance bearing stiffness / load capability compared to conventional systems. Using end covers with reduced thickness and eliminating the carrier plate results in a shorter and stiffer drive train compared to conventional systems.

[0048] Although some embodiments of the present disclosure are described in relation to PXs, energy recovery devices, and hydraulic energy transfer systems, the current disclosure can be applied to other systems and devices (e.g., PX that is not isobaric, rotating components that are not a PX, a PX that is not rotary, systems that do not include PXs, etc.).

[0049] 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.

[0050] FIGS. 1A-D illustrate schematic diagrams of fluid handling systems 100 including hydraulic energy transfer systems 110, according to certain embodiments.

[0051] In some embodiments, a hydraulic energy transfer system 110 includes a PX (e.g., PX). The PX may include one or more of the features described in one or more of FIGS. 3A-11.

[0052] The hydraulic energy transfer system 110 (e.g., PX) receives low-pressure (LP) fluid in 120 (e.g., low-pressure inlet stream) from a LP in system 122. The hydraulic energy transfer system 110 also receives high pressure (HP) fluid in 130 (e.g., high-pressure inlet stream) 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., low-pressure outlet stream) to LP fluid out system 142 and to provide HP fluid out 150 (e.g., high-pressure outlet stream) to HP fluid out system 152.

[0053] 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. The PX may be a device that transfers fluid pressure between HP fluid in 130 and LP fluid in 120 at efficiencies 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 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 the like. 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. Rotary PXs may be designed to operate with internal pistons to isolate fluids and transfer pressure with relatively little mixing of the inlet fluid streams. Reciprocating PXs may include a piston moving back and forth in a cylinder for transferring pressure between the fluid streams. Any PX or multiple PXs may be used in the present disclosure, such as, but not limited to, rotary PXs, reciprocating 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 100 (e.g., in situations in which the PX is added to an existing fluid handling system).

[0054] 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 in 130, etc.). In some embodiments, motor 160 generates energy (e.g., acts as a generator) based on pressure exchanging in hydraulic energy transfer system 110.

[0055] The hydraulic energy transfer system 110 may be a hydraulic protection system (e.g., hydraulic buffer system, hydraulic isolation system) that may block or limit contact between solid particle laden fluid (e.g., frac fluid) and various equipment (e.g., hydraulic fracturing equipment, high-pressure pumps) while exchanging work and / or pressure with another fluid. By blocking or limiting contact between various equipment (e.g., fracturing equipment) and solid particle containing fluid, the hydraulic energy transfer system 110 increases the life and performance, while reducing abrasion and wear, of various equipment (e.g., fracturing equipment, high pressure fluid pumps). Less expensive equipment may be used in the fluid handling system 100 by using equipment (e.g., high pressure fluid pumps) not designed for abrasive fluids (e.g., frac fluids and / or corrosive fluids).

[0056] The hydraulic energy transfer system 110 may include a hydraulic turbocharger or hydraulic pressure exchange system, such as a rotating PX. The PX may include one or more chambers (e.g., 1 to 100) to facilitate pressure transfer and equalization of pressures between volumes of first and second fluids (e.g., gas, liquid, multi-phase fluid). In some embodiments, the PX may transfer pressure between a first fluid (e.g., pressure exchange fluid, such as a proppant free or substantially proppant free fluid) and a second fluid that may be highly viscous and / or contain solid particles (e.g., frac fluid containing sand, proppant, powders, debris, ceramics). The solid particle fluid causes abrasion and / or erosion of components of the PX, such as the rotor and end covers of the PX. The fluid (e.g., abrasive particles in the fluid) may cause wear to an interface between the rotor and each end cover as the rotor rotates relative to the end covers. Replacing worn components of the PX may be costly.

[0057] The hydraulic energy transfer system 110 may be used in different types of systems, such as fracing systems, desalination systems, refrigeration systems, etc.

[0058] FIG. 1A illustrates a schematic diagram of a fluid handling system 100A including a hydraulic energy transfer system 110, according to certain embodiments. Fluid handling system 100A may include a control module 180 that includes one or more controllers 185.

[0059] FIG. 1B 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 a fracing system. In some embodiments, fluid handling system 100B includes more components, less components, same routing, different routing, and / or the like than that shown in FIG. 1B.

[0060] LP fluid in 120 and HP fluid out 150 may be frac fluid (e.g., fluid including solid particles, proppant fluid, etc.). HP fluid in 130 and LP fluid out 140 may be substantially solid particle free fluid (e.g., proppant free fluid, water, filtered fluid, etc.).

[0061] LP in system 122 may include one or more low-pressure fluid pumps to provide LP fluid in 120 to the hydraulic energy transfer system 110 (e.g., PX). HP in system 132 may include one or more high pressure fluid pumps 134 to provide HP fluid in 130 to hydraulic energy transfer system 110.

[0062] Hydraulic energy transfer system 110 exchanges pressure between LP fluid in 120 (e.g., low-pressure frac fluid) and HP fluid in 130 (e.g., high pressure water) to provide HP fluid out 150 (e.g., high pressure frac fluid) to HP out system 152 and to provide LP fluid out 140 (e.g., low-pressure water). HP out system 152 may include a rock formation 154 (e.g., well) that includes cracks 156. The solid particles (e.g., proppants) from HP fluid out 150 may be provided into the cracks 156 of the rock formation.

[0063] In some embodiments, LP fluid out 140, high pressure fluid pumps 134, and HP fluid in 130 are part of a first loop (e.g., proppant free fluid loop). The LP fluid out 140 may be provided to the high-pressure fluid pumps to generate HP fluid in 130 that becomes LP fluid out 140 upon exiting the hydraulic energy transfer system 110.

[0064] In some embodiments, LP fluid in 120, HP fluid out 150, and low-pressure fluid pumps 124 are part of a second loop (e.g., proppant containing fluid loop). The HP fluid out 150 may be provided into the rock formation 154 and then pumped from the rock formation 154 by the low-pressure fluid pumps 124 to generate LP fluid in 120.

[0065] In some embodiments, fluid handling system 100B is used in well completion operations in the oil and gas industry to perform hydraulic fracturing (e.g., fracking, fracing) to increase the release of oil and gas in rock formations 154. HP out system 152 may include rock formations 154 (e.g., a well). Hydraulic fracturing may include pumping HP fluid out 150 containing a combination of water, chemicals, and solid particles (e.g., sand, ceramics, proppant) into a well (e.g., rock formation 154) at high pressures. LP fluid in 120 and HP fluid out 150 may include a particulate laden fluid that increases the release of oil and gas in rock formations 154 by propagating and increasing the size of cracks 156 in the rock formations 154. The high pressures of HP fluid out 150 initiates and increases size of cracks 156 and propagation through the rock formation 154 to release more oil and gas, while the solid particles (e.g., powders, debris, etc.) enter the cracks 156 to keep the cracks 156 open (e.g., prevent the cracks 156 from closing once HP fluid out 150 is depressurized).

[0066] In order to pump this particulate laden fluid into the rock formation 154 (e.g., a well), the fluid handling system 100B may include one or more high pressure fluid pumps 134 and one or more low-pressure fluid pumps 124 coupled to the hydraulic energy transfer system 110. For example, the hydraulic energy transfer system 110 may be a hydraulic turbocharger or a PX (e.g., a rotary PX). In operation, the hydraulic energy transfer system 110 transfers pressures without any substantial mixing between a first fluid (e.g., HP fluid in 130, proppant free fluid) pumped by the high-pressure fluid pumps 134 and a second fluid (e.g., LP fluid in 120, proppant containing fluid, frac fluid) pumped by the low-pressure fluid pumps 124. In this manner, the hydraulic energy transfer system 110 blocks or limits wear on the high-pressure fluid pumps 134, while enabling the fluid handling system 100B to pump a high-pressure frac fluid (e.g., HP fluid out 150) into the rock formation 154 to release oil and gas. In order to operate in corrosive and abrasive environments, the hydraulic energy transfer system 110 may be made from materials resistant to corrosive and abrasive substances in either the first or second fluids. For example, the hydraulic energy transfer system 110 may be made out of ceramics (e.g., alumina, cermets, such as carbide, oxide, nitride, or boride hard phases) within a metal matrix (e.g., Co, Cr or Ni or any combination thereof) such as tungsten carbide in a matrix of CoCr, Ni, NiCr or Co.

[0067] In some embodiments, the hydraulic energy transfer system 110 includes a PX (e.g., rotary PX) and HP fluid in 130 (e.g., the first fluid, high-pressure solid particle free fluid) enters a first side of the PX where the HP fluid in 130 contacts LP fluid in 120 (e.g., the second fluid, low-pressure frac fluid) entering the PX on a second side. The contact between the fluids enables the HP fluid in 130 to increase the pressure of the second fluid (e.g., LP fluid in 120), which drives the second fluid out (e.g., HP fluid out 150) of the PX and down a well (e.g., rock formation 154) for fracturing operations. The first fluid (e.g., LP fluid out 140) similarly exits the PX, but at a low pressure after exchanging pressure with the second fluid. As noted above, the second fluid may be a low-pressure frac fluid that may include abrasive particles, which may wear the interface between the rotor and the respective end covers as the rotor rotates relative to the respective end covers.

[0068] FIG. 1C illustrates a schematic diagram of a fluid handling system 100C including a hydraulic energy transfer system 110, according to certain embodiments. Fluid handling system 100C may be a desalination system (e.g., remove salt and / or other minerals from water). In some embodiments, fluid handling system 100C includes more components, less components, same routing, different routing, and / or the like than that shown in FIG. 1C.

[0069] LP in system 122 may include a feed pump 126 (e.g., low-pressure fluid pump 124) that receives seawater in 170 (e.g., feed water from a reservoir or directly from the ocean) and provides LP fluid in 120 (e.g., low-pressure seawater, feed water) to hydraulic energy transfer system 110 (e.g., PX). HP in system 132 may include membranes 136 that provide HP fluid in 130 (e.g., high pressure brine) to hydraulic energy transfer system 110 (e.g., PX). The hydraulic energy transfer system 110 exchanges pressure between the HP fluid in 130 and LP fluid in 120 to provide HP fluid out 150 (e.g., high pressure seawater) to HP out system 152 and to provide LP fluid out 140 (e.g., low-pressure brine) to LP out system 142 (e.g., geological mass, ocean, sea, discarded, etc.).

[0070] The membranes 136 may be a membrane separation device configured to separate fluids traversing a membrane, such as a reverse osmosis membrane. Membranes 136 may provide HP fluid in 130 which is a concentrated feed-water or concentrate (e.g., brine) to the hydraulic energy transfer system 110. Pressure of the HP fluid in 130 may be used to compress low-pressure feed water (e.g., LP fluid in 120) to be high pressure feed water (e.g., HP fluid out 150). For simplicity and illustration purposes, the term feed water is used. However, fluids other than water may be used in the hydraulic energy transfer system 110.

[0071] The circulation pump 158 (e.g., turbine) provides the HP fluid out 150 (e.g., high pressure seawater) to membranes 136. The membranes 136 filter the HP fluid out 150 to provide LP potable water 172 and HP fluid in 130 (e.g., high pressure brine). The LP out system 142 provides brine out 174 (e.g., to geological mass, ocean, sea, discarded, etc.).

[0072] In some embodiments, a high-pressure fluid pump 176 is disposed between the feed pump 126 and the membranes 136. The high-pressure fluid pump 176 increases pressure of the low-pressure seawater (e.g., LP fluid in 120, provides high pressure feed water) to be mixed with the high-pressure seawater provided by circulation pump 158.

[0073] In some embodiments, use of the hydraulic energy transfer system 110 decreases the load on high pressure fluid pump 176. In some embodiments, fluid handling system 100C provides LP potable water 172 without use of high-pressure fluid pump 176. In some embodiments, fluid handling system 100C provides LP potable water 172 with intermittent use of high-pressure fluid pump 176.

[0074] In some examples, hydraulic energy transfer system 110 (e.g., PX) receives LP fluid in 120 (e.g., low-pressure feed-water) at about 30 pounds per square inch (PSI) and receives HP fluid in 130 (e.g., high-pressure brine or concentrate) at about 980 PSI. The hydraulic energy transfer system 110 (e.g., PX) transfers pressure from the high-pressure concentrate (e.g., HP fluid in 130) to the low-pressure feed-water (e.g., LP fluid in 120). The hydraulic energy transfer system 110 (e.g., PX) outputs HP fluid out 150 (e.g., high pressure (compressed) feed-water) at about 965 PSI and LP fluid out 140 (e.g., low-pressure concentrate) at about 15 PSI. Thus, the hydraulic energy transfer system 110 (e.g., PX) may be about 97% efficient since the input volume is about equal to the output volume of the hydraulic energy transfer system 110 (e.g., PX), and 965 PSI is about 97% of 980 PSI.

[0075] FIG. 1D illustrates a schematic diagram of a fluid handling system 100D including a hydraulic energy transfer system 110, according to certain embodiments. Fluid handling system 100D may be a refrigeration system. In some embodiments, fluid handling system 100D includes more components, less components, same routing, different routing, and / or the like than that shown in FIG. 1D.

[0076] Hydraulic energy transfer system 110 (e.g., PX) may receive LP fluid in 120 from LP in system 122 (e.g., low-pressure lift device 128, low-pressure fluid pump, etc.) and HP fluid in 130 from HP in system 132 (e.g., condenser 138). 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., high pressure lift device 159) and to provide LP fluid out 140 to LP out system 142 (e.g., evaporator 144). The evaporator 144 may provide the fluid to compressor 178 and low-pressure lift device 128. The condenser 138 may receive fluid from compressor 178 and high-pressure lift device 159.

[0077] The fluid handling system 100D 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) that is circulated in the closed system of fluid handling system 100D.

[0078] In some embodiments, the fluid of fluid handling system 100D may include solid particles. For example, the piping, equipment, connections (e.g., pipe welds, pipe soldering), etc. may introduce solid particles (e.g., solid particles from the welds) into the fluid in the fluid handling system 100D. The solid particles in the fluid and / or the high pressure of the fluid may cause abrasion and / or erosion of components (e.g., rotor, end covers) of the PX of hydraulic energy transfer system 110.

[0079] FIGS. 2A-E are exploded perspective views of a rotary PX 40 (e.g., rotary PX, rotary liquid piston compressor (LPC)), according to certain embodiments. PX 40 may include a motor 92 and / or a control module 94.

[0080] In some embodiments, PX 40 includes one or more of the features described in one or more of FIGS. 3A-11.

[0081] PX 40 is configured to transfer pressure and / or work between a first fluid (e.g., proppant free fluid or supercritical carbon dioxide, HP fluid in 130) and a second fluid (e.g., frac fluid or 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), 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. Similarly, the inlet port 60 may receive a low-pressure second fluid (e.g., LP fluid in 120) and the outlet port 62 may be used to route a high-pressure second fluid (e.g., 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.

[0082] As noted above, 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.

[0083] 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).

[0084] In some embodiments, a controller using sensor feedback (e.g., revolutions per minute measured through a tachometer or optical encoder or volume flow rate measured through flowmeter) may 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-D of FIGS. 1A-D). For example, varying the volume flow rates of the first and second fluids entering the rotary PX 40 allows the plant operator (e.g., system operator) to control the amount of fluid mixing within the PX 40. In addition, varying the rotational speed of the rotor 46 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 fluid barrier (e.g., an 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 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, a small portion of the rotor channel 70 is used for the exchange of pressure between the first and second fluids. Therefore, 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.

[0085] 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 that shown in FIGS. 2A-2E. As described in detail below, the rotary PX 40 facilitates pressure exchange between first and second fluids by enabling the first and second fluids to briefly contact each other within the rotor 46. In certain 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 the rotational speed of rotor 46 dictate whether any mixing occurs and to what extent.

[0086] 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. As will be discussed below, the rotor 46 may rotate in the clockwise direction indicated by arrow 84. In operation, low-pressure second fluid 86 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 and the first fluid 88.

[0087] 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 rotated clockwise 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.

[0088] 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.

[0089] 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.

[0090] Abrasion and / or erosion damage in a PX may occur when suspended solids are introduced and mixed in the fluid that enters the PX. Abrasion damage may occur when particles enter gaps in the PX (e.g., trapped between a stationary end cover and a rotating end cover). Erosion damage may occur due to existence of suspended solids (e.g., erodents) in high velocity fluid jets (e.g., slurry jets) that are formed due to the high pressure differentials inside the PX. When the high velocity jet makes an impact with components of the PX, the high velocity jet can cause damage to those components. Damage (e.g., erosion damage) can occur when a high-pressure rotor port (e.g., rotor duct) opens to a low-pressure end cover port (e.g., kidney) or when a low-pressure rotor port (e.g., rotor duct) opens to a high pressure end cover port (e.g., kidney) which causes a high pressure differential.

[0091] The PX of the present disclosure may have lower vibration levels at HPIN, HPOUT and LPOUT ports (e.g., within ASHRAE standards for refrigeration compressors) compared to conventional systems. The PX of the present disclosure may have lower noise levels (e.g., within limits adhered by compressor manufacturers) compared to conventional systems. The PX of the present disclosure may reduce mixing in the transcritical CO2 PX which may result in reduced enthalpy dilution at HPOUT and enhanced liquid fraction at LPOUT which may enhance PX energy savings. The present disclosure may reduce pressure drop across the PX (e.g., at higher flows and RPMs) which may result in reduced booster work and enhanced energy savings. The present disclosure may reduce leakage through the PX bearings which may enable increased refrigerant flow through the rotor increasing energy recovery. The present disclosure may reduce risk of cavitation and may enhance bearing stiffness and / or load capacity (e.g., of the PX). The present disclosure may have a reduced thickness of end covers and may reduce or eliminate the carrier plate which may result in a shorter and stiffer drive train and enhanced performance. The present disclosure may mate with a housing (e.g., redesigned housing) that enables an increase in HPOUT flow velocity which may reduce the chances of oil separation and accumulation in the PX.

[0092] In some embodiments, the present disclosure incudes a device (rotary PX) that exchanges pressure energy between two streams of CO2 in either liquid, gas or a mixture of the two phases.

[0093] FIGS. 3A-B illustrate PXs including end covers forming kidneys and rotors forming ducts, according to some embodiments.

[0094] In some embodiments, at least one of an HPIN, HPOUT, LPIN, or LPOUT kidney angular extents (e.g., an angular distance between an opening edge and a closing edge of a kidney) may be integral multiples of the duct angular extent (e.g., the spacing between adjacent ducts). In some embodiments, an angular extent can be a measure of the size or magnitude of an angle, typically in degrees, radians, or other angular units, which describes the amount of rotation or separation between two lines or rays that share a common vertex (e.g., an opening edge and a closing edge of a kidney). For example, if you have a circle (e.g., an end cover), the angular extent of a sector (a portion of the circle) is measured in degrees or radians and represents the angle formed by the two radii that define the sector. A full circle has an angular extent of 360 degrees (or 2π radians). If a sector covers only a fraction of the full circle, its angular extent is a proportion of 360 degrees (or 2π radians), depending on the fraction of the circle it represents. In some embodiments, an angular distance, when referring to a circle, can be the measure of the angle formed by two lines (or rays) that have their starting point at the center of the circle and extend to two different points on the circumference of the circle. This angle is typically measured in degrees or radians and tells you how far apart those two points are as you travel along the edge of the circle from one point to the other.

[0095] In some embodiments, integral multiples may also be referred to as integer multiples, whole-number multiples, etc. In mathematics, an integer can be a whole number. When you multiply a first integer by a second integer, the result is also an integer. When a first integer is multiplied by a second integer the resulting product is said to be an integer multiple (integral multiple) of both the first and second integers. For example, 21 is an integer multiple of both 7 and 3. In some embodiments, the duct angular spacing may be 30 degrees. An HPIN kidney angular extent in such a case could be an integer multiple of 30. For example, the HPIN kidney angular extent could be 60 degrees, 90 degrees, 120 degrees, 150 degrees, 180 degrees, 210 degrees, etc.

[0096] In some embodiments, spacing between ducts may be uniform for all ducts. By using kidney angular extents that are integral multiples of the spacing between the ducts (e.g., angular spacing of the ducts) as a duct begins to overlap with a kidney, another duct begins to leave (e.g., stop overlapping with) the kidney simultaneously. This results in a substantially constant amount of duct area of ducts of the rotor being open to (e.g., overlapping with) the kidney at substantially all instants. PX inlets may receive fluid from positive displacement compressors (e.g., have constant volumetric flow rate) and any variation in duct area open to (e.g., overlapping with) the kidney will result in flow acceleration and deceleration and corresponding unwanted pressure fluctuations. In some embodiments, PXs of the present disclosure include a duct area of rotor ducts open to the kidneys of the end covers that is substantially constant (e.g., by using kidney angular extents that are integral multiples of the angular spacing between ducts). This avoids pressure fluctuations and avoids vibrations and noise that result from pressure fluctuations.

[0097] In some embodiments, a PX may include a rotor 360 configured to receive a first fluid, receive a second fluid, and exchange pressure between the first fluid and the second fluid. In some embodiments, rotor 360 may form a plurality of ducts (e.g., ducts 310A-C of FIG. 3A and FIG. 3B).

[0098] In some embodiments, the PX may further include a first end cover 330 fluidly coupled with rotor 360. The first end cover 330 may form a first kidney 320 (e.g., fluid is to travel between a duct 310 of rotor 360 and kidney 320 of the first end cover 330). In some embodiments, a kidney angular extent 340 of first kidney 320 may be substantially an integer multiple of a duct angular spacing 350A between at least two adjacent ducts (e.g., ducts 310B and 310C) of the plurality of ducts. In some embodiments, kidney angular extent 340 is an angular distance between an opening edge 301 and a closing edge 302 of first kidney 320 and duct angular spacing 350A is an angular distance between corresponding centers of the at least two adjacent ducts (e.g., ducts 310B and 310C). In some embodiments, a kidney angular extent of a kidney being substantially an integer multiple of a duct angular spacing between at least two adjacent ducts (e.g., ducts 310B and 310C) of the plurality of ducts may include the angular extents being within + / − ten percent of being integer multiples. For example, kidney angular extent 340 would allow for a duct angular spacing between at least two adjacent ducts such that the duct area exposed to the kidney does not vary in time by more than 10%.

[0099] In some embodiments, a kidney opening edge is the edge of the kidney where a duct begins to overlap with the kidney as the rotor rotates. In some embodiments, a kidney closing edge is the edge of the kidney where a duct begins to decrease overlap and stops overlapping with the kidney as the rotor rotates. For example, in FIG. 3B, duct 310A is depicted as it begins to overlap with kidney 320 at opening edge 301 of kidney 320. In another example, in FIG. 3B, duct 310C is depicted as it begins to decrease overlap with kidney 320 at closing edge 302 of kidney 320.

[0100] In some embodiments, a kidney having an angular extent that is substantially an integer multiple of a duct angular spacing (e.g., the angular distance between two adjacent ducts) causes the duct area (e.g., of ducts of the rotor) open to the kidney to remain substantially constant as the rotor rotates leading to reduced flow ripple and pressure pulsations. In some embodiments, reducing flow ripple and pressure pulsations in PXs is beneficial for enhancing performance and efficiency. Flow ripple, characterized by variations in flow rate, and pressure pulsations, involving periodic pressure fluctuations, can lead to operational inefficiencies, equipment wear, and potential downstream issues. By minimizing these undesirable fluctuations, PXs can operate more reliably, efficiently, and with less mechanical stress, resulting in extended equipment life, energy savings, and improved system performance.

[0101] For example, in FIGS. 3A and 3B the duct area open to kidney 320 remains substantially constant even though the ducts (e.g., ducts 310A-C) may be continuously rotating past kidney 320. In conventional systems, the kidney angular extent is not substantially an integer multiple of the duct angular spacing and the duct area open to the kidney area does not remain substantially constant with time leading to high flow ripple and pressure pulsations. High flow ripple and pressure pulsations are detrimental because they reduce system efficiency, increase equipment wear, and can disrupt the stability of fluid systems, leading to operational issues and potential damage.

[0102] In some embodiments, an angular extent of a kidney may be 40 degrees and the duct angular spacing could be about 10 degrees.

[0103] In some embodiments, a kidney angular extent of a kidney being substantially an integer multiple of a duct angular spacing between at least two adjacent ducts (e.g., ducts 310B and 310C) of the plurality of ducts may include the angular extents being within + / − ten percent of being integer multiples.

[0104] In some embodiments, kidneys and duct may be a substantially similar shape (e.g., trapezoidal). In some embodiments, using kidney shapes matched with duct shape maximizes radial sealing and reduces leakage. Using kidney-shapes with the same radial extent as the ducts can enhance radial sealing and minimizing leakage. Radial sealing helps fluids or gases to remain contained. Kidney-shaped seals, with a curved and conformable design, can create secure seals. When these seals are matched to the corresponding duct or channel shapes within a system, they can enhance the sealing process by closely fitting the contours of the duct. Such a seal maximizes the contact area between the seal and the duct walls, reducing the potential for leakage and enhancing the overall integrity, reliability, and performance of the system. In some embodiments, the PX of the present disclosure has kidneys matched with ducts to maximize radial sealing lands.

[0105] In some embodiments, the rotor of the present disclosure has trapezoidal ducts instead of circular maximize the duct area density in the kidney annulus, resulting in lower max velocity in the duct and thus lower inertial losses.

[0106] FIGS. 3C-D are associated with PXs, according to some embodiments. A PX of the present disclosure may include features of one or more of FIGS. 3C-D.

[0107] FIG. 3C illustrates an end cover, according to some embodiments. In some embodiments, one or more end covers of a PX includes a seal area (e.g., spacing between a spot features of the end cover) of about a rotor duct width plus a rotor duct wall width as shown in FIG. 3C.

[0108] In some embodiments, end cover 330 includes a seal area 375 (e.g., spacing between kidneys of the end cover, spacing between spot features of the end cover, etc.) of about a rotor duct width 385 plus a rotor duct wall width 395 as shown in FIG. 3C. In some embodiments, the rotor duct wall may be the barrier between two adjacent ducts formed by the rotor.

[0109] FIG. 3D illustrates a seal plate, according to some embodiments. In some embodiments, a PX includes a passageway from LPIN aperture 384 to an LPIN center bore 382. In some embodiments, LPIN aperture 384 may be an LPIN kidney. In some embodiments, the PX of the present disclosure has LPIN as center bore fluid instead of LPOUT which reduces loss of liquid refrigerant and also reduces leakage overall.

[0110] In some embodiments, one or more end covers of a PX includes one or more pre-ramps. In some embodiments, one or more end covers of a PX includes an early open (e.g., about 5 degrees). For example, a ramp may start 5 degrees early at LPOUT.

[0111] In some embodiments, the present disclosure (e.g., PX) may have dual functions of expansion device and compressor. In some embodiments, the PX of the present disclosure has an increased duct size that enables lower RPM for the same flow rates, reducing the number of pressure cycles in a given time which reduces noise and vibrations. In some embodiments, the PX of the present disclosure has dual ramps on each kidney which enables smooth entry and exit of the fluid from the rotor, reducing shock losses. In some embodiments, the PX of the present disclosure has bearing stiffness that is increased by using shallow circumferential grooves and increased radial bearing clearances. In some embodiments, the PX of the present disclosure has axial clearance reduction to minimize leakage.

[0112] In some embodiments, the PX of the present disclosure has enhanced kidney sizes that results in multiple ducts open to the kidney at the same time reducing the pressure and flow pulsations at the ports and thereby reducing vibrations.

[0113] In some embodiments, the PX of the present disclosure has spot face addition at the HPOUT and LPOUT ports that reduces the rapidity of duct pressurization and depressurization. This reduces mixing and noise.

[0114] In some embodiments, the present disclosure includes a PX-based energy recovery device in a transcritical CO2 refrigeration system or a heat pump and its derivative applications. In some embodiments, the PX of the present disclosure reduces energy consumption in a transcritical CO2 refrigeration cycle, heat pump cycle and its derivatives.

[0115] FIG. 4 illustrates end covers 430 and 432, according to some embodiments.

[0116] In some embodiments, the first end cover 430 of FIG. 4 is a same or similar end cover as end cover 430 in FIGS. 3A-B.

[0117] In some embodiments, a PX may include a rotor configured to receive a first fluid, receive a second fluid, and exchange pressure between the first fluid and the second fluid. In some embodiments, the rotor may form a plurality of ducts (e.g., ducts 310A-C of FIG. 3A and FIG. 3B).

[0118] In some embodiments, the PX may further include a first end cover 430 fluidly coupled with the rotor, first end cover 430 forming a first kidney 420.

[0119] In some embodiments, a PX may include a second end cover 432 fluidly coupled to the rotor. In some embodiments, first end cover 430 may be fluidly couple to a first distal end of the rotor and second end cover 432 may be fluidly coupled to a second distal end of the rotor. In some embodiments, first end cover 430 and second end cover 432 substantially align allowing for precise placement of kidneys (e.g., a first kidney 420 and a second kidney 422) with relation to each other. For example, first end cover 430 and second end cover 432 may align in such a way that the first kidney 420 and second kidney 422 are offset (e.g., there is a delay angle between the first and second kidneys, a low-pressure duct opens to an HPOUT kidney on the first end cover before opening to an HPIN kidney on the second end cover, a high-pressure duct opens to an LPOUT kidney on the first end cover before opening to an LPIN kidney on the second end cover, etc.)

[0120] In some embodiments, second end cover 432 forms a second kidney 422. In some embodiments, a delay angle 470 between first kidney 420 of first end cover 430 and second kidney 422 of second end cover 432 ranges from 15 to 20 degrees. In some embodiments, delay angle 470 is an angular distance between a closing edge 403 of second kidney 422 of second end cover 432 and closing edge 401 of first kidney 420 of first end cover 430. In some embodiments, first kidney 420 includes a closing edge 402 and second kidney 422 includes a closing edge 404. In some embodiments, delay angle 470 can also be described as an angular distance between opening edge 404 of second kidney 422 of second end cover 432 and opening edge 402 of first kidney 420 of first end cover 430.

[0121] In some embodiments, first end cover 430 and second end cover 432 substantially align allowing for precise placement of kidneys (e.g., third kidney 424 and a fourth kidney 426) with relation to each other. For example, first end cover 430 and second end cover 432 may align in such a way that the third kidney 424 and fourth kidney 426 are offset (e.g., there is a delay angle between the third and fourth kidneys, a low-pressure duct opens to an HPOUT kidney on the first end cover before opening to an HPIN kidney on the second end cover, a high-pressure duct opens to an LPOUT kidney on the first end cover before opening to an LPIN kidney on the second end cover, etc.)

[0122] In some embodiments, second end cover 432 forms a third kidney 424. In some embodiments, a delay angle 460 between third kidney 424 of second end cover 432 and fourth kidney 426 of first end cover 430 ranges from 15 to 20 degrees. In some embodiments, delay angle 460 is an angular distance between an opening edge 413 of fourth kidney 426 of first end cover 430 and an opening edge 411 of third kidney 424 of second end cover 432. In some embodiments, third kidney 424 includes a closing edge 412 and fourth kidney 426 includes a closing edge 414. In some embodiments, delay angle 460 can also be described as an angular distance between closing edge 414 of fourth kidney 426 of first end cover 430 and closing edge 412 of third kidney 424 of second end cover 432.

[0123] In some embodiments, the PX of the present disclosure has a delayed opening of HPIN kidney in relation to HPOUT kidney. A PX may have reduced or no HPIN fluid exiting via HPOUT (e.g., no mixing). Some conventional systems have a rotating duct (carrying low-pressure (LP) fluid) opening to both HPIN and HPOUT kidneys at the same time which results in the duct being pressurized by fluid from both HPIN and HPOUT kidneys thereby causing large mixing and reducing the enthalpy at HPOUT. The PX of the present disclosure may reduce this mixing by opening the LP duct (e.g., a duct containing LP fluid) to HPOUT before opening to HPIN. With the delay angle (e.g., an optimum delay angle), the duct gets pressurized (e.g., pressurized purely) by HPOUT. When the duct opens to HPIN, pressure difference is small (with respect to the duct) which reduces mixing (e.g., no pressure driven jetting) and the duct contents are pushed out to HPOUT in a near plug flow manner. In some embodiments, a near plug flow manner can refer to a flow that is uniform and continuous, with minimal mixing or turbulence.

[0124] A near plug flow manner may describe the behavior of a fluid as it moves through a conduit or system (e.g., a PX). This flow pattern is characterized by minimal lateral mixing, ensuring that fluid elements move in close proximity to each other without significant dispersion. The velocity profile remains relatively uniform across the cross-section of a conduit, with orderly progression of fluid elements, and low turbulence. This controlled and organized flow is particularly useful in applications where maintaining the identity of fluid elements and minimizing mixing is important for efficient and predictable processes.

[0125] Enthalpy may refer to a fundamental thermodynamic concept representing the total energy content of a system. Enthalpy, denoted as H, comprises both the internal energy (U) of the system and the product of its pressure (P) and volume (V), as expressed by the equation H =U+PV. Enthalpy can describe how the mixing of substances within a system (e.g., a PX) impacts the overall energy content and pressure of the system. The mixing process can lead to changes in ability to absorb or reject heat, affecting the behavior of the system. In some embodiments, two fluids of different enthalpies when mixed result in an intermediate enthalpy. This mixing can be driven by the pressure dynamics within a PX.

[0126] In some embodiments, the PX of the present disclosure has a delayed opening of LPIN kidney in relation to LPOUT kidney. In some embodiments, a PX has reduced mixing. For example relatively little high pressure (HP) duct fluid may end up in LPIN. Some conventional solutions have a rotating duct carrying HP fluid opening to both LPIN and LPOUT kidneys at the same time which results in the duct fluid expanding into both LPIN and LPOUT kidneys at the same time (pressure driven jetting). To prevent this from happening, a rotor duct containing HP fluid of the present disclosure is allowed to open to (e.g., aligns with) LPOUT kidney first (e.g., with a delay angle, with an optimum delay angle) which results in the duct contents expanding into LPOUT and duct pressure equalizing. Subsequently when the duct opens to LPIN, mixing is reduced (e.g., pressure driven expansion into LPIN is avoided) and the contents are pushed out into LPOUT in a plug flow manner.

[0127] In some embodiments, the PX of the present disclosure has a delayed HPIN opening that moves the pressure and flow pulsation events to HPOUT instead of HPIN. Since the fluid is purely gas or mostly gas at HPOUT, the fluid at HPOUT has lower density and can handle the pulsations better (e.g., a given flow pulsation translates into a lower pressure pulsation) as opposed to the fluid at HPIN.

[0128] FIG. 5 illustrates an end cover, according to some embodiments.

[0129] In some embodiments, an end cover 500 (e.g., fluidly coupled with a rotor) forms a first kidney 510. In some embodiments, end cover 500 forms a second kidney 520. In some embodiments, fluid flow between ports (not shown in FIG. 5) of a PX and a rotor may be through first kidney 510 and second kidney 520. In some embodiments, a ratio of a size of the first kidney 510 to a size of the second kidney 520 ranges from 3:2 to 5:2. In some embodiments, kidney size may be a surface area of the kidney (e.g., a ratio of a surface area 512 of the first kidney 510 to a surface area 522 of the second kidney 520 ranges from 3:2 to 5:2).

[0130] In some embodiments, the PX of the present disclosure has unequal HP and LP kidney sizes. Since the density of HP fluid is many times higher than the density of LP fluid, pressure losses due to inertia (caused by the duct fluid being accelerated and decelerated continuously) are higher on the HP side than on the LP side. This results in imbalanced rotor thrust. By sizing the HP kidneys and LP kidneys differently, inertial DP losses on both HP and LP kidneys can be balanced better resulting in reduced rotor thrust loads.

[0131] In some embodiments, first end cover 500 includes an end cover surface 502 (e.g., that faces the rotor). In some embodiments, end cover surface 502 forms a buffer chamber 560 disposed in a delay region 580 of end cover 500. A buffer chamber can be a recess formed on the surface of an end cover. In some embodiments, the buffer can face the rotor or another moving component in the PX. The primary function of a buffer chamber can be to serve as a space or cavity designed to stabilize fluid flow and minimize pressure fluctuations, particularly in applications where controlled flow is essential (e.g., PXs). Buffer chambers can also equalize pressure differentials, reduce turbulence, and can assist in heat dissipation. In some embodiments, buffer chambers can separate and capture particulate matter or contaminants, ensuring cleaner downstream fluid or gas.

[0132] In some embodiments, delay region 580 is a region between an opening edge 530 of first kidney 510 of the first end cover and an opening edge 530 of first kidney 510 of the second end cover. In some embodiments, a kidney opening edge is the edge of the kidney where a duct begins to overlap with the kidney as the rotor rotates. In some embodiments, a kidney closing edge is the edge of the kidney where a duct begins to decrease overlap and stops overlapping with the kidney as the rotor rotates. For example, arrow 590 shows the rotation direction of the rotor. In some embodiments, ducts will pass over first kidney 510, second kidney 520, and buffer chamber 560 in the direction indicated by arrow 590.

[0133] In some embodiments, a spacing between the buffer chamber and the kidneys is at least as wide as one duct (e.g., duct 550). This may prevent HPIN fluid (or other fluids in alternative embodiments) from entering the buffer chamber.

[0134] In some embodiments, buffer chamber 560 is a substantially similar shape (e.g., trapezoidal) as first kidney 510 and has an angular extent 562 substantially equal to an angular extent of a rotor duct of the rotor. In some embodiments, buffer chamber 560 is a substantially similar shape (e.g., trapezoidal) as first kidney 510 and may have an angular extent 562 that is substantially double angular extent 592 of the rotor duct of the rotor. In some embodiments, buffer chamber 560 may be a blind recess. In some embodiments, buffer chamber 560 may minimize pressure fluctuations in the PX.

[0135] In some embodiments, first kidney 510 may be an HPIN kidney and second kidney 520 may be an LPOUT kidney. In some embodiments, first kidney 510 may be an HPOUT kidney and second kidney 520 may be an LPIN kidney. Conventional solutions (e.g., using high-pressure and low-pressure kidneys of the same size) cause pressure losses. Because the density of the high-pressure fluid is many times higher than the density of low-pressure fluid the high-pressure fluid has higher inertia (e.g., caused by the duct fluid being accelerated and decelerated continuously). This results in imbalanced rotor thrust in conventional solutions. In some embodiments, using unequal kidney sizes between high-pressure and low-pressure kidneys (e.g., By sizing the HP kidneys larger than the LP kidneys) causes inertial differential pressure losses for both high-pressure and low-pressure kidneys to be more balanced resulting in reduced rotor thrust loads.

[0136] In some embodiments, fluid flow between ports of the PX and the rotor is through first kidney 510 and second kidney 520. In some embodiments, a ratio of a size of first kidney 510 to a size of second kidney 520 ranges from about 3:2 to about 5:2.

[0137] FIG. 6 illustrates an end cover 600 including a buffer chamber 670, according to some embodiments.

[0138] In some embodiments, a PX includes a rotor configured to receive a first fluid, receive a second fluid, and exchange pressure between the first fluid and the second fluid. In some embodiments, the rotor forms a plurality of ducts. In some embodiments, the PX includes a first end cover 600 fluidly coupled with the rotor, first end cover 600 forming a first kidney 620.

[0139] In some embodiments, first end cover 600 forms a second kidney 622, first end cover 600 including a first end cover surface 602 that faces the rotor, first end cover surface 602 forming a buffer chamber 670 disposed in a delay region 680 of first end cover 600. In some embodiments, delay region 680 is a region between a closing edge 660 of buffer chamber 670 and an opening edge 630 of first kidney 620. In some embodiments, delay region 680 is a region between the opening edge 630 of first kidney 620 on first end cover 600 and an opening edge of a second kidney on a second end cover. The opening edge 630 of first kidney 620 on first end cover 600 is represented by the dotted line 660 in FIG. 6.

[0140] In some embodiments, a kidney opening edge is the edge of the kidney where a duct begins to overlap with the kidney as the rotor rotates. In some embodiments, a kidney closing edge is the edge of the kidney where a duct begins to decrease overlap and stops overlapping with the kidney as the rotor rotates. For example, arrow 690 shows the rotation direction of the rotor. In some embodiments, ducts will pass over first kidney 620, second kidney 622, and buffer chamber 670 in the direction indicated by arrow 690.

[0141] In some embodiments, a buffer chamber opening edge is the edge of the buffer chamber where a duct begins to overlap with the buffer chamber as the rotor rotates. In some embodiments, a buffer chamber closing edge is the edge of the buffer chamber where a duct begins to decrease overlap and stops overlapping with the buffer chamber as the rotor rotates.

[0142] In some embodiments, buffer chamber 670 is a substantially similar shape (e.g., trapezoidal) as first kidney 620 and has an angular extent 682 substantially equal to an angular extent of the rotor duct of the rotor. In some embodiments, fluid flow between ports of the PX and the rotor is through first kidney 620 and second kidney 622. In some embodiments, a ratio of a size of first kidney 620 to a size of second kidney 622 ranges from about 3:2 to about 5:2.

[0143] In some embodiments, a spacing between the buffer chamber and the kidneys is at least as wide as one duct (e.g., duct 650). This may prevent HPIN fluid (or other fluids in alternative embodiments) from entering the buffer chamber.

[0144] In some embodiments, line 660 indicates where an HPOUT kidney opens on a second end cover. See FIGS. 7A-B and 8A-B for a more detailed description.

[0145] FIG. 7A illustrates a PX having a rotor and end covers forming a buffer chamber, according to some embodiments.

[0146] In some embodiments, PX includes a rotor 730A configured to receive a first fluid, receive a second fluid, and exchange pressure between the first fluid and the second fluid. In some embodiments, rotor 730A forms a plurality of ducts (e.g., LP duct 760A). In some embodiments, HP duct refers to a duct containing HP fluid. In some embodiments, the PX includes a first end cover 710A fluidly coupled with rotor 730A, first end cover 710A forming a first kidney 750A. In some embodiments, second end cover 712A forms a second kidney HPOUT kidney 740A. In some embodiments, first end cover 710A includes a first end cover surface 770A that faces rotor 730A, first end cover surface 770A forming a buffer chamber 720A disposed in a delay region (e.g., upstream of HPIN kidney 750A) of first end cover 710A. In some embodiments, the delay region may be a region between an opening edge of the second kidney 740A (shown by the dotted line 761A) on the second end cover and an opening edge of first kidney 750A.

[0147] In some embodiments, a PX 700A may include a buffer chamber 720A on an HPIN end cover 710A upstream of HPIN kidney 750A in the delay area (e.g., between an opening edge of HPIN kidney 750A and the opening edge of the HPOUT kidney 740A). In some embodiments, buffer chamber 720A may be a blind recess having similar shape and radial extent as the rotor ducts. In some embodiments, buffer chamber 720A may be machined into HPIN end cover 710A in the delay region. In some embodiments, the starting angle of the blind recess (e.g., buffer chamber 720A) matches the starting angle of HPOUT kidney 740A (e.g., buffer chamber 720A and HPOUT kidney are substantially aligned). Line 761A shows the matching starting angles of buffer chamber 720A and HPOUT kidney 740A. In some embodiments, the ending angle of the blind recess (e.g., buffer chamber 720A) may be set to prevent any communication with HPIN kidney 750A through the ducts. In some embodiments, the blind recess may store a “buffer” of HPOUT fluid continually.

[0148] In some embodiments, PX 700A, includes a second end cover 712A fluidly coupled to rotor 730A. In some embodiments, second end cover 712A forms a third kidney 740A. In some embodiments, when a first duct (e.g., partly pressurized duct 764A) of the plurality of ducts substantially aligns with buffer chamber 720A, third kidney 740A substantially aligns with the first duct (e.g., as shown by line 761A).

[0149] In some embodiments, third kidney 740A may be an HPOUT kidney and the first and second ducts may be low-pressure ducts (e.g., ducts filled with low-pressure fluid). In some embodiments, first kidney 750A may be an HPIN kidney, and the first duct (e.g., partly pressurized duct 764A) substantially aligns with first kidney 750A after aligning with buffer chamber 720A. For example, partially pressurized duct 764A will only align with first kidney 750A after rotating past buffer chamber 720A.

[0150] In some embodiments, a kidney angular extent of the first kidney 750A may be substantially an integer multiple of a duct angular extent between at least two adjacent ducts (e.g., LP duct 760A and partly pressurized duct 764A) of the plurality of ducts. In some embodiments, LP duct refers to a duct containing LP fluid. In some embodiments, the kidney angular extent is an angular distance between an opening edge and a closing edge of first kidney 750A and the duct angular extent is an angular distance between corresponding centers of the at least two adjacent ducts.

[0151] In some embodiments, when a duct (e.g., LP duct 760A) carrying low-pressure fluid opens to the HPOUT kidney 740A, the duct may be simultaneously open to buffer chamber 720A, causing the LP duct 760A to be pressurized from a first distal end and a second distal end of the duct simultaneously. In some embodiments, a duct getting pressurized simultaneously at the first distal end (e.g., by HPOUT kidney 740A) and the second distal end (e.g., by buffer chamber 720A) may cause the duct to pressurize faster and may also dampen the amplitude of pressure waves in the duct reducing jetting (e.g., when open to HPIN kidney 750A) and reducing mixing.

[0152] In some embodiments, buffer chamber 720A is a substantially similar shape (e.g., trapezoidal) as first kidney 750A and has an angular extent substantially equal to an angular extent of a rotor duct (e.g., partly pressurized rotor duct 764A). In some embodiments, fluid flow between ports of the PX 700A and rotor 730A is through first kidney 750A and a third kidney formed by end cover 710A. In some embodiments, a ratio of a size of first kidney 750A to a size of the second kidney ranges from 3:2 to 5:2.

[0153] In some embodiments, a spacing between the buffer chamber and the kidneys is at least as wide as one duct. This may prevent HPIN fluid (or other fluids in alternative embodiments) from entering the buffer chamber.

[0154] FIG. 7B illustrates a PX having a rotor and end covers forming a buffer chamber, according to some embodiments.

[0155] In some embodiments, a PX 700B includes a rotor 730B configured to receive a first fluid, receive a second fluid, and exchange pressure between the first fluid and the second fluid. In some embodiments, rotor 730B includes a plurality of ducts (e.g., LP duct 760B). In some embodiments, PX 700B includes a first end cover 710B fluidly coupled with rotor 730B. In some embodiments, first end cover 710B includes a first end cover surface 770B that faces rotor 730B. In some embodiments, first end cover surface 770B forms a buffer chamber 720B disposed in a delay region (see FIGS. 5 and 6) of first end cover 710B. In some embodiments, first end cover 710B forms a first kidney 750B. In some embodiments, second end cover 712B forms a second kidney 740B. In some embodiments, the delay region is a region between an opening edge of first kidney 750B on the end cover 710B and the opening edge of first kidney 740B on the second end cover 712B.

[0156] In some embodiments, PX 700B includes a second end cover 712B fluidly coupled to rotor 730B. In some embodiments, second end cover 712B forms a third kidney 740B. In some embodiments, a first duct and a second duct (e.g., partly pressurized ducts 764B) of the plurality of ducts substantially align with buffer chamber 720B simultaneously (e.g., as shown by lines 761B and 762B) while third kidney 740B substantially aligns with the first duct (e.g., as shown by line 761B).

[0157] In some embodiments, third kidney 740B may be an HPOUT kidney and the first and second ducts may be low-pressure ducts (e.g., ducts filled with low-pressure fluid). In some embodiments, first kidney 750B may be an HPIN kidney, and the first duct substantially aligns with first kidney 750B after aligning with buffer chamber 720B. For example, partially pressurized ducts 764B will only align with first kidney 750B after rotating past buffer chamber 720B.

[0158] In some embodiments, a kidney angular extent of the first kidney 750B may be substantially an integer multiple of a duct angular extent between at least two adjacent ducts (e.g., partly pressurized ducts 764B) of the plurality of ducts. In some embodiments, the kidney angular extent is an angular distance between an opening edge and a closing edge of first kidney 750B and the duct angular extent is an angular distance between corresponding centers of the at least two adjacent ducts.

[0159] In some embodiments, buffer chamber 720B is a substantially similar shape (e.g., trapezoidal) as first kidney 750B and has an angular extent substantially double the angular extent of rotor duct 764B. In some embodiments, fluid flow between ports of the PX 700B and rotor 730B is through first kidney 750B and the third kidney formed by end cover 710B. In some embodiments, a ratio of a size of first kidney 750B to a size of the second kidney ranges from 3:2 to 5:2.

[0160] In some embodiments, a spacing between the buffer chamber and the kidneys is at least as wide as one duct. This may prevent HPIN fluid (or other fluids in alternative embodiments) from entering the buffer chamber.

[0161] FIG. 8A illustrates a PX having a rotor and end covers forming a buffer chamber, according to some embodiments.

[0162] In some embodiments, a buffer chamber may be implemented upstream of an LPIN kidney in the delay area (see FIGS. 5 and 6). This effectively increases the delay angle, enabling the high-pressure duct to begin depressurizing before it opens to LPOUT kidney.

[0163] In some embodiments, PX 800A includes a rotor 830A configured to receive a first fluid, receive a second fluid, and exchange pressure between the first fluid and the second fluid. In some embodiments, rotor 830A forms a plurality of ducts (e.g., HP duct 860A, partly depressurized duct 864A, etc.). In some embodiments, HP duct refers to a duct containing HP fluid. In some embodiments, PX 800A includes a first end cover 810A fluidly coupled with rotor 830A. In some embodiments, first end cover 810A forms a first kidney 850A. In some embodiments, first kidney 850A may be an LPIN kidney. In some embodiments, first end cover 810A forms a second kidney (not shown in FIG. 8A). In some embodiments, first end cover 810A includes a first end cover surface 870A that faces rotor 830A. In some embodiments, first end cover surface 870A forms a buffer chamber 820A disposed in a delay region (e.g., upstream of HPIN kidney 850A) of first end cover 810A. In some embodiments, the delay region may be a region between the opening edge of the first kidney 850A and an opening edge (e.g., line 861A) of first kidney 840A. In some embodiments, upstream indicated a direction that is contrary to the direction of rotation of the rotor.

[0164] In some embodiments, PX 800A may include a buffer chamber 820A on an LPIN end cover 810A upstream of LPIN kidney 850A in the delay area (e.g., between an opening edge of LPIN kidney 850A and an opening edge of the LPOUT kidney 840A). In some embodiments, buffer chamber 820A may be a blind recess having similar shape and radial extent as the kidneys. In some embodiments, buffer chamber 820A may be machined into LPIN end cover 810A in the delay region. In some embodiments, the starting angle of the blind recess (e.g., buffer chamber 820A) matches the starting angle of LPOUT kidney 840A (e.g., buffer chamber 820A and LPOUT kidney are substantially aligned). Line 861A shows the matching starting angles of buffer chamber 820A and LPOUT kidney 840A. In some embodiments, the ending angle of the blind recess (e.g., buffer chamber 820A) may be set to prevent any communication with LPIN kidney 850A through the ducts. In some embodiments, the blind recess may store a “buffer” of LPOUT fluid continually.

[0165] In some embodiments, PX 800A, includes a second end cover 812A fluidly coupled to rotor 830A. In some embodiments, second end cover 812A forms a third kidney 840A. In some embodiments, when a first duct (e.g., partly depressurized duct 864A) of the plurality of ducts substantially aligns with buffer chamber 820A, third kidney 840A substantially aligns with the first duct (e.g., as shown by line 861A).

[0166] In some embodiments, third kidney 840A may be an LPOUT kidney and the first and second ducts may be high pressure ducts (e.g., ducts filled with high-pressure fluid). In some embodiments, first kidney 850A may be an LPIN kidney, and the first duct substantially aligns with first kidney 850A after aligning with buffer chamber 820A. For example, partially pressurized duct 864A will only align with first kidney 850A after rotating past buffer chamber 820A.

[0167] In some embodiments, a kidney angular extent of the first kidney 850A may be substantially an integer multiple of a duct angular extent between at least two adjacent ducts (e.g., LP duct 860A and partly pressurized duct 864A) of the plurality of ducts. In some embodiments, the kidney angular extent is an angular distance between an opening edge and a closing edge of first kidney 850A and the duct angular extent is an angular distance between corresponding centers of the at least two adjacent ducts.

[0168] In some embodiments, when a duct (e.g., HP duct 860A) carrying high-pressure fluid opens to the LPOUT kidney 840A, the duct may be simultaneously open to buffer chamber 820A, causing the HP duct 860A to be depressurized from a first distal end and a second distal end of the duct simultaneously. In some embodiments, a duct being depressurized simultaneously at the first distal end (e.g., by LPOUT kidney 840A) and the second distal end (e.g., by buffer chamber 820A) may cause the duct to depressurize faster and may also dampen the amplitude of pressure waves in the duct reducing jetting (e.g., when open to LPIN kidney 850A) and reducing mixing.

[0169] In some embodiments, buffer chamber 820A is a substantially similar shape (e.g., trapezoidal) as first kidney 850A and has an angular extent substantially equal to an angular extent of rotor duct 860A In some embodiments, fluid flow between ports of the PX 800A and rotor 830A is through first kidney 850A and a third kidney formed by end cover 810A. In some embodiments, a ratio of a size of first kidney 850A to a size of the second kidney ranges from 3:2 to 5:2.

[0170] In some embodiments, a spacing between the buffer chamber and the kidneys is at least as wide as one duct. This may prevent LPIN fluid (or other fluids in alternative embodiments) from entering the buffer chamber.

[0171] FIG. 8B illustrates a PX having a rotor and end covers forming a buffer chamber, according to some embodiments.

[0172] In some embodiments, a PX 800B includes a rotor 830B configured to receive a first fluid, receive a second fluid, and exchange pressure between the first fluid and the second fluid. In some embodiments, rotor 830B includes a plurality of ducts (e.g., HP duct 860B, partly depressurized ducts 864B, etc.). In some embodiments, PX 800B includes a first end cover 810B fluidly coupled with rotor 830B. In some embodiments, first end cover 810B includes a first end cover surface 870B that faces rotor 830B. In some embodiments, first end cover surface 870B forms a buffer chamber 820B disposed in a delay region (see FIGS. 5 and 6) of first end cover 810B. In some embodiments, first end cover 810B forms a first kidney 850B and a second kidney (not shown in FIG. 8B). In some embodiments, the delay region is a region between an opening edge of the first kidney 840B and an opening edge of first kidney 850B.

[0173] In some embodiments, PX 800B includes a second end cover 812B fluidly coupled to rotor 830B. In some embodiments, second end cover 812B forms a third kidney 840B. In some embodiments, a first duct and a second duct (e.g., partly pressurized ducts 864B) of the plurality of ducts substantially align with buffer chamber 820B simultaneously (e.g., as shown by lines 861B and 862B) while third kidney 840B substantially aligns with the first duct (e.g., as shown by line 861B).

[0174] In some embodiments, third kidney 840B may be an LPOUT kidney and the first and second ducts may be high pressure ducts (e.g., ducts filled with high-pressure fluid). In some embodiments, first kidney 850B may be an LPIN kidney, and the first duct substantially aligns with first kidney 850B after aligning with buffer chamber 820B. For example, partially pressurized ducts 864B will only align with first kidney 850B after rotating past buffer chamber 820B.

[0175] In some embodiments, a kidney angular extent of the first kidney 850B may be substantially an integer multiple of a duct angular extent between at least two adjacent ducts (e.g., partly pressurized ducts 864B) of the plurality of ducts. In some embodiments, the kidney angular extent is an angular distance between an opening edge and a closing edge of first kidney 850B and the duct angular extent is an angular distance between corresponding centers of the at least two adjacent ducts.

[0176] In some embodiments, buffer chamber 820B is a substantially similar shape (e.g., trapezoidal) as first kidney 850B and has an angular extent substantially double the angular extent of rotor duct 860B. In some embodiments, fluid flow between ports of the PX 800B and rotor 830B is through first kidney 850B and a third kidney formed by end cover 810B. In some embodiments, a ratio of a size of first kidney 850B to a size of the second kidney ranges from 3:2 to 5:2.

[0177] In some embodiments, a spacing between the buffer chamber and the kidneys is at least as wide as one duct. This may prevent LPIN fluid (or other fluids in alternative embodiments) from entering the buffer chamber.

[0178] FIG. 9 illustrates a rotor forming ducts, according to some embodiments.

[0179] In some embodiments, a rotor 900 may be configured to receive a first fluid, receive a second fluid, and exchange pressure between the first fluid and the second fluid. In some embodiments, rotor 900 forms a plurality of ducts (e.g., inner ducts 910, outer ducts 920, etc.).

[0180] In some embodiments, rotor 900 forms the ducts in a plurality of concentric rows (e.g., inner row 912, outer row 922, etc.). For example, inner ducts 910 form inner row 912 and outer ducts 920 form outer row 922. In some embodiments, inner row 912 and outer row 922 are concentric rows. In some embodiments, concentric rows may refer to a pattern in which multiple rows of objects (e.g., ducts) are arranged in a circular manner, with each row positioned at a distance from the center, creating a series of circles or rings. In some embodiments, the rows may be staggered. For example, line 930 and line 932 show how ducts of inner ring 912 and ducts of the outer ring 922 may be staggered. In some embodiments, the use of staggered rows may reduce the total amount of duct volume that pressurizes and / or depressurizes at a time which reduces noise and vibration of the PX.

[0181] In some embodiments, using multiple rows of staggered ducts may reduce pressure pulsations at an HPOUT port and HPOUT kidney. For example, when a low-pressure duct (e.g., filled with LPIN fluid) opens to the HPOUT kidney, a jet of fluid rushes into the low-pressure duct due to the pressure differential, resulting in a short near-instantaneous flow reversal at the HPOUT port. This flow reversal causes an instantaneous pressure drop at the HPOUT port, resulting in pressure pulsations and vibrations. By increasing the number of ducts and reducing the size of each duct (total duct volume remains constant), the magnitude of flow reversal and duration is kept small. This results in lower pressure pulsations and corresponding vibrations at the HPOUT port.

[0182] In some embodiments, duct size may be increased to enable higher flow rates with lower RPMs, reducing the number of pressure cycles in a given time, and thereby reducing noise and vibrations. In some embodiments, larger kidney sizes may result in multiple ducts being open to the kidney (e.g., overlapping the kidney) simultaneously reducing the pressure and flow pulsations at the ports and thereby reducing vibrations. In some embodiments, trapezoidal ducts may be used (e.g., instead of circular ducts) to maximize the duct area density in the kidney annulus, resulting in lower max velocity in the duct and thus lower inertial losses.

[0183] In some embodiments, using an odd number of ducts (e.g., instead of an even number) enables temporal separation of pressurization and depressurization events. This results in reduced noise & vibrations.

[0184] FIG. 10 illustrates a pre-pressurization hole, according to some embodiments.

[0185] In some embodiments, pre-pressurizing a low-pressure duct before the low-pressure duct opens to an HPOUT kidney 1010 can be accomplished using a kidney pre-pressurization opening 1020, a pre-pressurization conduit 1030, and a pre-pressurization opening 1000 connecting the HPOUT kidney 1010 to the low-pressure duct when upstream of the HPOUT kidney 1010. This allows for pre-pressurization of the duct and allows for faster stabilization of pressure when the duct eventually opens to HPOUT kidney 1010. In some embodiments, the conduit 1030 and a pre-pressurization opening 1000 are disposed in end cover 1040. In some embodiments, pre-pressurization opening 1000 faces the rotor (e.g., fluidly coupled to end cover 1040. Arrow 1070 indicates the rotation direction of the rotor (e.g., fluidly connected to the end cover).

[0186] FIG. 11A illustrates a spot face according to certain embodiments.

[0187] In some embodiments, an HP kidney may have a spotface that is deeper than conventional spotfaces. For example, a PX may include rotor 1110A forming ducts. The PX may further include an end cover 1100A including an HP kidney 1120A. HP kidney 1120A includes a spotface 1190A that is deeper than conventional spotfaces. In some embodiments, a deeper spotface addition may be at the HPOUT or LPOUT ports and may reduce the rapidity of duct pressurization and depressurization. This reduces mixing and noise. Compressible fluids such as CO2 can choke when leaking through the spot face from HP Kidney (e.g., HP kidney 1120A) into an LP duct. This effectively limits the rate of the LP duct pressurization. An alternative spot face design (e.g., deeper spot faces) allows for faster pressurization even when the pressure ratio exceeds the critical pressure ratio for choking.

[0188] Conventional PXs may include an HP kidney having a spotface that is shallow. For example, a conventional PX may include a rotor forming ducts. The conventional PX may further include an end cover including an HP kidney. The HP kidney can include a spotface that is shallow. A shallow spotface can reduce the rapidity of duct pressurization and depressurization. This reduces mixing and noise. Compressible fluids such as CO2 choke when leaking through the spot face from HP Kidney (e.g., HP kidney 1120A) into an LP duct. This effectively limits the rate of the LP duct pressurization.

[0189] 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 order to 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.

[0190] 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.

[0191] 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.

[0192] 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 reading and 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.

Examples

Embodiment Construction

[0020]Embodiments described herein are related to transcritical refrigeration PXs.

[0021]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 hydraulic fracturing (e.g., fracking or fracing) systems, desalinization systems, refrigeration systems, heat pump systems, energy generation systems, mud pumping systems, slurry pumping systems, industrial fluid systems, waste fluid systems, fluid transportation systems, etc. Pumps or compressors may be used to increase pressure of fluids of such systems.

[0022]Conventionally, 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 (CO...

Claims

1. A pressure exchanger (PX) comprising:a rotor configured to receive a first fluid, receive a second fluid, and exchange pressure between the first fluid and the second fluid, wherein the rotor forms a plurality of ducts; anda first end cover fluidly coupled with the rotor, the first end cover forming a first kidney, wherein a kidney angular extent of the first kidney is substantially an integer multiple of a duct angular spacing between at least two adjacent ducts of the plurality of ducts, wherein the kidney angular extent is an angular distance between an opening edge and a closing edge of the first kidney and the duct angular spacing is an angular distance between corresponding centers of the at least two adjacent ducts.

2. The PX of claim 1, further comprising a second end cover fluidly coupled with the rotor, wherein the second end cover forms a second kidney, wherein a delay angle between the first kidney of the first end cover and the second kidney of the second end cover ranges from 15 to 20 degrees, and wherein the delay angle is an angular distance between a closing edge of the second kidney and an closing edge of the first kidney.

3. The PX of claim 1, wherein the rotor forms the ducts in a plurality of concentric rows, wherein the rows are staggered.

4. The PX of claim 1, further comprising a second end cover, wherein the second end cover forms a second kidney, the first end cover comprising a first end cover surface that faces the rotor, the first end cover surface forming a buffer chamber disposed in a delay region of the first end cover, wherein the delay region is a region between an opening edge of the second kidney and an opening edge of the first kidney.

5. The PX of claim 1, wherein the first end cover forms a third kidney, wherein fluid flow between ports of the PX and the rotor is through the first kidney and the third kidney, and wherein a ratio of a size of the first kidney to a size of the third kidney ranges from 3:2 to 5:2.

6. A pressure exchanger (PX) comprising:a rotor configured to receive a first fluid, receive a second fluid, and exchange pressure between the first fluid and the second fluid, wherein the rotor forms a plurality of ducts;a first end cover fluidly coupled with the rotor, the first end cover comprising a first end cover surface that faces the rotor, the first end cover surface forming a buffer chamber disposed in a delay region of the first end cover, wherein the first end cover forms a first kidney; anda second end cover forming a second kidney, wherein the delay region is a region between an opening edge of the second kidney and an opening edge of the first kidney.

7. The PX of claim 6, further comprising a second end cover fluidly coupled to the rotor, the second end cover forming a third kidney, wherein when a first duct of the plurality of ducts substantially aligns with the buffer chamber, the third kidney substantially aligns with the first duct.

8. The PX of claim 7, wherein the first duct and a second duct of the plurality of ducts substantially align with the buffer chamber simultaneously while the third kidney substantially aligns with the first duct.

9. The PX of claim 8, wherein the third kidney is a high pressure out (HPOUT) kidney and the first and second ducts are low-pressure ducts.

10. The PX of claim 9, wherein the first kidney is a high pressure in (HPIN) kidney, and the first duct substantially aligns with the first kidney after aligning with the buffer chamber.

11. The PX of claim 8, wherein the third kidney is a low pressure out (LPOUT) kidney and the first and second ducts are high pressure ducts.

12. The PX of claim 11, wherein the first kidney is a low pressure in (LPIN) kidney, and the first duct substantially aligns with the first kidney after aligning with the buffer chamber.

13. The PX of claim 7, wherein a kidney angular extent of the first kidney is substantially an integer multiple of a duct angular spacing between at least two adjacent ducts of the plurality of ducts, wherein the kidney angular extent is an angular distance between an opening edge and a closing edge of the first kidney and the duct angular spacing is an angular distance between corresponding centers of the at least two adjacent ducts.

14. The PX of claim 7, wherein the buffer chamber is a substantially similar shape as the first kidney and has an angular extent substantially equal to or substantially double an angular extent of a rotor duct of the plurality of ducts.

15. The PX of claim 6, wherein the first end cover forms a third kidney, wherein fluid flow between ports of the PX and the rotor is through the first kidney and the third kidney, and wherein a ratio of a size of the first kidney to a size of the second kidney ranges from 3:2 to 5:2.

16. A pressure exchanger (PX) comprising:a rotor configured to receive a first fluid, receive a second fluid, and exchange pressure between the first fluid and the second fluid; anda first end cover fluidly coupled with the rotor, the first end cover forming a first kidney and a second kidney, wherein fluid flow between ports of the PX and the rotor is through the first kidney and the second kidney, and wherein a ratio of a size of the first kidney to a size of the second kidney ranges from 3:2 to 5:2.

17. The PX of claim 16, wherein the first kidney is a high-pressure kidney, and the second kidney is a low-pressure kidney.

18. The PX of claim 17, further comprising a second end cover fluidly coupled with the rotor, the second end cover forming a third kidney and a fourth kidney, wherein fluid flow between ports of the PX and the rotor is through the third kidney and the fourth kidney, and wherein a ratio of a size of the third kidney to a size of the fourth kidney ranges from 3:2 to 5:2.

19. The PX of claim 18, wherein the third kidney is a high-pressure kidney, and the fourth kidney is a low-pressure kidney.

20. The PX of claim 16, wherein the rotor forms a plurality of ducts, wherein a kidney angular extent of the first kidney is substantially an integer multiple of a duct angular spacing between at least two adjacent ducts of the plurality of ducts, wherein the kidney angular extent is an angular distance between an opening edge and a closing edge of the first kidney and the duct angular spacing is an angular distance between corresponding centers of the at least two adjacent ducts.

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