Refrigeration system with high-speed rotary pressure exchanger

Abstract

A refrigeration system includes a rotary pressure exchanger fluidly coupled to a low-pressure branch and a high-pressure branch. The rotary pressure exchanger is configured to receive a high-pressure refrigerant from the high-pressure branch, receive a low-pressure refrigerant from the low-pressure branch, and exchange pressure between the high-pressure refrigerant and the low-pressure refrigerant, and wherein a first outflow stream from the rotary pressure exchanger includes the high-pressure refrigerant in a supercritical state or a subcritical state, and a second outflow stream from the rotary pressure exchanger includes the low-pressure refrigerant in a liquid state or a two-phase mixture of liquid and vapor.

Description

[0001] This application is a divisional application of a patent application with an application date of July 1, 2021, application number 202180049554.9 (international application number PCT / US2021 / 040199), and invention name “Refrigeration system with high-speed rotary pressure exchanger”. Background Art

[0002] This section is intended to introduce the reader to various aspects of the technology that may be related to the various aspects of the present invention described and / or defined below. It is believed that this discussion helps to provide the reader with background information to facilitate a better understanding of the various aspects of the present invention. Therefore, it should be understood that these statements should be read as such and not as an admission of the prior art.

[0003] With government environmental agencies enforcing regulations, large parts of the world are now being forced to convert to zero global warming cooling systems, such as transcritical CO2 refrigeration. Transcritical CO2 systems work well in relatively cold climates, such as much of Europe and North America, but face disadvantages in hot climates because their coefficient of performance (a measure of efficiency) decreases as the ambient temperature increases, resulting in higher electricity costs per unit of cooling. This is because transcritical CO2 systems need to operate at much greater pressures (about 10,342 kPa (1500 psi) or greater) than HFC / CFC-based systems (about 1,379-2,068.4 kPa (200-300 psi). In order to keep the refrigerant above the critical pressure, a very high differential pressure compressor is used. The large pressure ratio on the compressor consumes more electrical energy. This problem is exaggerated in warmer climates because the refrigerant temperature at the chiller inlet needs to be increased to a high enough temperature to be able to reject the heat to the surrounding warmer environment. This is achieved by increasing the pressure ratio on the compressor higher, resulting in a greater power demand on the compressor and, in turn, an increased power cost per unit of cooling performed. Improvements in the efficiency of refrigeration systems (e.g., transcritical CO2 refrigeration systems) can reduce the operating costs of refrigeration equipment and increase its availability while helping to reduce global warming. Summary of the invention

[0004] The following summarizes certain embodiments that are commensurate in scope with the disclosed subject matter. These embodiments are not intended to limit the scope of the present disclosure, but these embodiments are only intended to provide a brief summary of certain disclosed embodiments. In fact, the present disclosure can include various forms that are similar or different from the embodiments set forth below.

[0005] In one embodiment, a refrigeration system is provided. The refrigeration system includes a high-pressure branch for circulating a high-pressure refrigerant through it. The refrigeration system also includes a gas cooler or condenser arranged along the high-pressure branch, wherein the high-pressure branch is configured to discharge heat from the high-pressure refrigerant to the surrounding environment via the gas cooler or condenser, and the high-pressure refrigerant is in a supercritical state or a subcritical state. The refrigeration system includes a low-pressure branch for circulating a low-pressure refrigerant through it. The refrigeration system also includes an evaporator arranged along the low-pressure branch, wherein the low-pressure branch is configured to absorb heat from the surrounding environment into the low-pressure refrigerant via the evaporator, and the low-pressure refrigerant is in a liquid state, a vapor state, or a two-phase mixture of liquid and vapor. The refrigeration system also includes a compressor or a pump, which is configured to increase the pressure of the refrigerant from a low pressure to a high pressure. The refrigeration system even includes a rotary pressure exchanger, which is fluidly connected to the low-pressure branch and the high-pressure branch, wherein the rotary pressure exchanger is configured to receive high-pressure refrigerant from the high-pressure branch, receive low-pressure refrigerant from the low-pressure branch, and exchange pressure between the high-pressure refrigerant and the low-pressure refrigerant, and wherein a first outflow flow from the rotary pressure exchanger includes a high-pressure refrigerant in a supercritical state or a subcritical state, and a second outflow flow from the rotary pressure exchanger includes a low-pressure refrigerant in a liquid state or a two-phase mixture of liquid and vapor.

[0006] In one embodiment, a refrigeration system is provided. The refrigeration system includes a high-pressure branch for circulating a high-pressure refrigerant through it. The refrigeration system includes a gas cooler or condenser arranged along the high-pressure branch, wherein the high-pressure branch is configured to discharge heat from the high-pressure refrigerant to the surrounding environment via the gas cooler or condenser, and the high-pressure refrigerant is in a supercritical state or a subcritical state. The refrigeration system also includes a low-pressure branch for circulating a low-pressure refrigerant through it. The refrigeration system further includes a first evaporator arranged along the low-pressure branch, wherein the first evaporator is configured to operate at a first temperature, wherein the low-pressure branch is configured to absorb heat from the surrounding environment into the low-pressure refrigerant via the evaporator, and the low-pressure refrigerant is in a liquid state, a vapor state, or a two-phase mixture of liquid and vapor. The refrigeration system further includes a first intermediate pressure branch for circulating a first intermediate pressure refrigerant through it. The refrigeration system further includes a second evaporator arranged along the first intermediate pressure branch, wherein the second evaporator is configured to operate at a second temperature greater than the first temperature. The refrigeration system further comprises a second intermediate pressure branch for circulating a second intermediate pressure refrigerant therethrough, wherein a first intermediate pressure of the refrigerant in the first intermediate pressure branch is between corresponding pressures of the refrigerants in the low pressure branch and the second intermediate pressure branch, the first intermediate pressure of the refrigerant in the first intermediate pressure branch is equal to a saturation pressure at the second evaporator, and the corresponding pressure of the refrigerant in the second intermediate pressure branch is between corresponding pressures of the refrigerants in the high pressure branch and the first intermediate pressure branch. The refrigeration system further includes: a flash tank configured to operate at a second intermediate pressure and separate the refrigerant in a two-phase mixture of liquid and vapor into pure liquid and pure vapor; and a rotary pressure exchanger fluidly connected to the second intermediate pressure branch and the high-pressure branch, wherein the rotary pressure exchanger is configured to receive the high-pressure refrigerant from the high-pressure branch, receive the second intermediate-pressure refrigerant in a vapor state, a liquid state, or a two-phase mixture of liquid and vapor from the second intermediate pressure branch, and exchange the pressure between the high-pressure refrigerant and the second intermediate-pressure refrigerant, and wherein the first outflow stream from the rotary pressure exchanger includes the high-pressure refrigerant in a supercritical state or a subcritical state, and the second outflow stream from the rotary pressure exchanger includes the second intermediate-pressure refrigerant in a liquid state or a two-phase mixture of liquid and vapor.

[0007] In one embodiment, a refrigeration system is provided. The refrigeration system includes a high-pressure branch for circulating a high-pressure refrigerant through it. The refrigeration also includes a gas cooler or condenser arranged along the high-pressure branch, wherein the high-pressure branch is configured to discharge heat from the high-pressure refrigerant to the surrounding environment via the gas cooler or condenser, and the high-pressure refrigerant is in a supercritical state or a subcritical state. The refrigeration system further includes a second low-pressure branch for circulating a low-pressure refrigerant through it. The refrigeration system further includes a first evaporator arranged along the low-pressure branch, wherein the first evaporator is configured to operate at a first temperature, wherein the low-pressure branch is configured to absorb heat from the surrounding environment into the low-pressure refrigerant via the evaporator, and the low-pressure refrigerant is in a liquid state, a vapor state, or a two-phase mixture of liquid and vapor. The refrigeration system even further includes an intermediate-pressure branch for circulating an intermediate-pressure refrigerant through it. The refrigeration system further includes a second evaporator arranged along the intermediate-pressure branch, wherein the second evaporator is configured to operate at a second temperature greater than the first temperature. The intermediate pressure of the refrigerant in the intermediate pressure branch is between the corresponding pressures of the refrigerants in the high pressure branch and the low pressure branch, and the intermediate pressure of the refrigerant in the intermediate pressure branch is equal to the saturation pressure at the second evaporator. The refrigeration system further includes a flash tank, which is configured to operate at the intermediate pressure and separate the refrigerant in a two-phase mixture of liquid and vapor into pure liquid and pure vapor. The refrigeration system further includes a rotary pressure exchanger, which is fluidly connected to the intermediate pressure branch and the high pressure branch, wherein the rotary pressure exchanger is configured to receive the high pressure refrigerant from the high pressure branch, receive the intermediate pressure refrigerant in a vapor state, a liquid state, or a two-phase mixture of liquid and vapor from the intermediate pressure branch, and exchange the pressure between the high pressure refrigerant and the intermediate pressure refrigerant, and wherein the first outflow from the rotary pressure exchanger includes the high pressure refrigerant in a supercritical state or a subcritical state, and the second outflow from the rotary pressure exchanger includes the intermediate pressure refrigerant in a liquid state or a two-phase mixture of liquid and vapor. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The various features, aspects and advantages of the present invention will be better understood when the following detailed description is read with reference to the accompanying drawings, in which like characters represent like parts in the various drawings, and in which:

[0009] Figure 1 is the phase diagram of carbon dioxide;

[0010] Figure 2 is a schematic diagram of an embodiment of a refrigeration system with a rotary pressure exchanger or a rotary liquid piston compressor (LPC);

[0011] Figure 3The refrigeration system using the Joule-Thomson expansion valve is shown in FIG. Figure 2 Temperature-entropy diagram of the thermodynamic process of the refrigeration system;

[0012] Figure 4 It is a refrigeration system that uses a Joule-Thomson expansion valve. Figure 2 Pressure-enthalpy diagram of the thermodynamic process of the refrigeration system;

[0013] Figure 5 is an exploded perspective view of an embodiment of a rotary pressure exchanger or a rotary LPC;

[0014] Figure 6 is an exploded perspective view of an embodiment of a rotary pressure exchanger or rotary LPC in a first operating position;

[0015] Figure 7 is an exploded perspective view of an embodiment of a rotary pressure exchanger or rotary LPC in a second operating position;

[0016] Figure 8 is an exploded perspective view of an embodiment of a rotary pressure exchanger or rotary LPC in a third operating position;

[0017] Fig. 9 is an exploded perspective view of an embodiment of a rotary pressure exchanger or rotary LPC in a fourth operating position;

[0018] Fig.10 is an exploded view of an embodiment of a rotor with a barrier system;

[0019] Fig.11 is a cross-sectional view of an embodiment of a rotor with a barrier system;

[0020] Fig.12 is a cross-sectional view of an embodiment of a rotor with a barrier system;

[0021] Fig.13 is a cross-sectional view of an embodiment of a rotor with a barrier system;

[0022] Fig.14 It is along Fig.11 A cross-sectional view of an embodiment of a barrier member along line 14-14;

[0023] Fig.15 It is along Fig.11 A cross-sectional view of an embodiment of a barrier member along line 14-14;

[0024] Fig.16 is a cross-sectional view of an embodiment of a rotary pressure exchanger or a rotary liquid piston compressor with a cooling system;

[0025] Fig.17is a cross-sectional view of an embodiment of a rotary pressure exchanger or a rotary liquid piston compressor with a heating system;

[0026] Fig.18 is a schematic diagram of an embodiment of a refrigeration system in a supermarket refrigeration system architecture;

[0027] Fig.19 is a schematic diagram of an embodiment of a refrigeration system in an alternative supermarket refrigeration system architecture;

[0028] Fig. 20 is a schematic diagram of an embodiment of a control system that controls the movement of a power fluid and a working fluid in a RLPC;

[0029] Fig.21 is a schematic diagram of an embodiment of a control system that controls the movement of a power fluid and a working fluid in a RLPC;

[0030] Fig.22A is a schematic diagram of an embodiment of a refrigeration system with a rotary pressure exchanger or a rotary liquid piston compressor (LPC) (e.g., with a low flow, high differential pressure (DP) leakage pump and a low DP, high flow circulation pump in place of a high flow compressor);

[0031] Fig. 22B is a schematic diagram of an embodiment of a refrigeration system with a rotary pressure exchanger or a rotary liquid piston compressor (LPC) (e.g., with a leaking compressor instead of a high flow compressor);

[0032] Fig.23 is a temperature-entropy diagram of a thermodynamic process in a refrigeration system of FIG22;

[0033] Fig.24 is the pressure-enthalpy diagram of the thermodynamic process in the refrigeration system of FIG22;

[0034] Fig.25 is a schematic diagram of an embodiment of a refrigeration system with a rotary pressure exchanger or a rotary liquid piston compressor (LPC) (e.g., with a leak compressor instead of a high-flow compressor and an additional low-DP recycle compressor (e.g., a blower));

[0035] Fig.26 is a schematic diagram of an embodiment of a refrigeration system in a supermarket refrigeration system architecture (eg, with an expansion valve); and

[0036] Fig. 27 is a schematic diagram of an embodiment of a refrigeration system in a supermarket refrigeration system configuration (eg, with an expansion valve). DETAILED DESCRIPTION

[0037] One or more specific embodiments of the present invention will be described below. These embodiments described are only examples of the present invention. In addition, in the effort to provide an accurate description of these exemplary embodiments, all features of the actual implementation may not be described in the specification. It should be understood that, like any engineering or design project, in the development of any such actual implementation, a large number of specific implementation decisions must be made to achieve the specific goals of the developer, such as complying with the limitations of related systems and related businesses that may vary in different implementations. In addition, it should be understood that such development work may be complex and time-consuming, but it is a routine task of design, production and processing for those skilled in the art who can benefit from the present invention. It should also be understood that the features of the different embodiments disclosed herein can be combined with each other, unless otherwise stated.

[0038] The following discussion describes a refrigeration system (e.g., a transcritical carbon dioxide refrigeration system) that utilizes a rotary pressure exchanger or a rotary liquid piston compressor or a rotary liquid piston pump to replace a Joule-Thomson expansion valve. As will be explained below, the refrigeration system can operate more efficiently by increasing the cooling capacity of the refrigeration system while recapturing much of the pressure energy that would otherwise be lost using the Joule-Thomson expansion valve. Replacing the Joule-Thomson expansion valve with a rotary pressure exchanger improves efficiency due to the elimination of the entropy generation and exergy destruction that occurs in the expansion valve, which can result in up to 40% of the total losses in a typical refrigeration system. In addition, replacing the Joule-Thomson expansion valve with a rotary pressure exchanger improves efficiency by changing the expansion process from an isenthalpic (i.e., constant enthalpy) process across the expansion valve to an isentropic or near-isentropic (i.e., constant entropy) process across the rotary pressure exchanger. In certain embodiments, the rotary pressure exchanger can also replace the function of a high-flow compressor. This enables the use of one or more low differential pressure (DP) circulating compressors (blowers) or circulating pumps to replace high flow, high differential pressure compressors and maintain flow within the refrigeration system (e.g., to overcome small pressure losses). These low DP circulating compressors can consume significantly less energy (e.g., 10 times or more) than high flow compressors. Replacing the Joule-Thomson expansion valve and high flow compressor with a rotary pressure exchanger removes the two largest sources of inefficiency in the refrigeration system while providing less power consumption and power costs. In addition, the use of a rotary pressure exchanger instead of an expansion valve and / or a high flow compressor can increase the availability of the refrigeration system in other environments (e.g., warmer environments). Warmer ambient temperatures (e.g., 50 degrees Celsius) change the compressor pressure ratio (by significantly increasing the pressure required at the compressor outlet) and significantly reduce the cycle efficiency (i.e., coefficient of performance) by up to 60% compared to the optimal temperature (e.g., 35 degrees Celsius). The use of a rotary pressure exchanger mitigates the adverse effects of warmer ambient temperatures on the required compressor work, the cooling capacity of the refrigeration system, and the coefficient of performance of the refrigeration system.

[0039] In operation, the rotary pressure exchanger or rotary liquid piston compressor or pump can completely or incompletely equalize the pressure between the first fluid and the second fluid. Thus, the rotary liquid piston compressor or pump can operate isobarically or substantially isobarically (e.g., wherein the pressures of the first fluid and the second fluid are equalized within approximately + / - 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10% of each other). A rotary liquid piston compressor or pump can generally be defined as a device that transfers fluid pressure between a high pressure inlet stream and a low pressure inlet stream with an efficiency exceeding approximately 50%, 60%, 70%, 80%, or 90%.

[0040] Figure 1 It is the phase of carbon dioxide Figure 2 A phase diagram shows the equilibrium limits of various phases in a chemical system versus temperature and pressure. Figure 1 Phase Figure 2 shows how carbon dioxide changes phase (e.g., gas (vapor), liquid, solid, supercritical) as temperature and pressure change. In addition to showing when carbon dioxide exists as a gas or vapor, liquid, and solid, the phase Figure 2 It also shows when carbon dioxide turns into a supercritical fluid. When a compound is subjected to pressure and temperature above its critical point, it becomes a supercritical fluid. The critical point is the point at which the surface tension (meniscus) that separates the liquid and gas phases of a substance disappears and the two phases become indistinguishable. In the supercritical region, the fluid exhibits special properties. These properties can include gases having liquid-like density (e.g., an order of magnitude higher), specific heat, viscosity, and the speed of sound through them.

[0041] Figure 2 is a schematic diagram of an embodiment of a refrigeration system 800 (e.g., a transcritical carbon dioxide refrigeration system) using a fluid in a supercritical state. Although the refrigeration system 800 is described as utilizing carbon dioxide, other refrigerants may also be utilized. Replacing an expansion valve (e.g., a Joule-Thomson valve) in the refrigeration system 800 with a rotary pressure exchanger or rotary liquid compressor 802 (indicated in the figure by PX) as described below enables the refrigeration system 800 to operate more efficiently by increasing the cooling capacity of the refrigeration system 800 while recapture much of the pressure energy that would otherwise be lost using a Joule-Thomson expansion valve. In certain embodiments, the rotary pressure exchanger can replace the function of a high-flow compressor, and thus, one or more low-DP circulating compressors or pumps (which are significantly more energy efficient) can be utilized in place of the high-flow compressor. For example, a transcritical carbon dioxide refrigeration system needs to operate at a greater pressure (approximately 10,342 kPa (1500 psi) or greater), which creates a large pressure ratio on the compressor (a very high differential pressure compressor), resulting in more electrical energy consumption. Replacing the expansion valve with a rotary pressure exchanger enables nearly all of the pressure drop to be recaptured in the rotary pressure exchanger and then used to pressurize the flow from the evaporator, rather than sending the flow to the main compressor. Thus, the power requirements of the compressor can be significantly reduced or eliminated. The refrigeration system 800 utilizing a rotary pressure exchanger in place of a Joule-Thomson expansion valve and / or a high-flow compressor can be used in a variety of applications, including supermarket refrigeration systems, heating, ventilation, and / or air conditioning (HVAC) systems, refrigeration for liquefied natural gas systems, industrial refrigeration for the chemical processing industry, battery technology (e.g., using a combination of refrigeration and power cycles to create a solar or wind thermal energy storage system), aquariums, polar habitat research systems, and any other system utilizing refrigeration.

[0042] As shown, the refrigeration system 800 includes a first fluid circuit (e.g., a high-pressure branch) 804 for circulating a high-pressure refrigerant (e.g., carbon dioxide) and a second fluid circuit (e.g., a low-pressure circuit) 806 for circulating a low-pressure refrigerant (e.g., carbon dioxide) at a pressure lower than that in the high-pressure circuit 804. The first fluid circuit 804 includes a heat exchanger 808 (e.g., a gas cooler / condenser) and a rotary pressure exchanger 802. The heat exchanger 808 discharges heat from the high-pressure refrigerant to the surrounding environment. Although the gas cooler described below is used for a supercritical high-pressure refrigerant (e.g., carbon dioxide), in some embodiments, the condenser can be used for a subcritical high-pressure refrigerant (e.g., carbon dioxide). The subcritical state of the refrigerant is below the critical point (specifically, between the critical point and the triple point). The second fluid circuit 806 includes a heat exchanger 810 (e.g., such as a cooling or heat load of an evaporator) and a rotary pressure exchanger 802. The heat exchanger 810 absorbs heat from the surrounding environment into the low-pressure refrigerant. The low-pressure refrigerant in the low-pressure loop 806 can be a liquid, a vapor, or a two-phase mixture of liquid and vapor. Both fluid loops 804 and 806 are fluidly connected to a compressor 812 (e.g., a large flow compressor). The compressor 812 converts the superheated gaseous carbon dioxide received from the evaporator 810 (by increasing the temperature and pressure) into supercritical carbon dioxide provided to the gas cooler 808. In certain embodiments, as described in more detail below, the compressor 812 can be replaced by one or more low-DP circulating compressors or pumps to overcome the small pressure loss within the system 800 and maintain fluid flow. Typically, along the first fluid loop 804, the gas cooler 808 receives carbon dioxide in a supercritical state and then provides it to the rotary pressure exchanger 802 (e.g., at the high-pressure inlet 822) after some cooling. Along the second fluid loop 804, the evaporator 810 provides a first portion of the superheated gaseous carbon dioxide to the low-pressure inlet 813 of the rotary pressure exchanger 802, and provides a second portion of the superheated gaseous carbon dioxide to the compressor 812. The rotary pressure exchanger 802 exchanges pressure between the carbon dioxide in a supercritical state and the superheated gaseous carbon dioxide. The carbon dioxide in a supercritical state is converted into a two-phase gas / liquid mixture within the rotary pressure exchanger 80 and leaves the low pressure outlet 824, where it is provided to the evaporator 810. The rotary pressure exchanger 802 also increases the pressure and temperature of the superheated gaseous carbon dioxide to convert it into carbon dioxide in a supercritical state, which leaves the rotary pressure exchanger 802 via the high pressure outlet 815, where it is provided to the gas cooler 808. Figure 2 As shown, the supercritical carbon dioxide exiting the rotary pressure exchanger 802 may be combined with carbon dioxide provided to the gas cooler 808 from the compressor 812 .

[0043] refer to Figure 3 and Figure 4 The thermodynamic processes occurring in refrigeration system 800 are described in greater detail (eg, relative to refrigeration systems utilizing Joule-Thomson valves). Figure 3 and Figure 4 A temperature-entropy (T-S) diagram 814 and a pressure-enthalpy (P-H) diagram 816 are shown to illustrate the thermodynamic processes occurring at the four major components of the refrigeration system 800, as compared to a refrigeration system including a Joule-Thomson expansion valve. Point 1 represents the compressor inlet 818 (see Figure 2 Point 2 represents the compressor outlet 820 and the gas cooler inlet 820. Point 3 represents the gas cooler outlet 822 and the expansion valve inlet (in a refrigeration system with a Joule-Thomson expansion valve) or high pressure inlet 822 of the rotary liquid compressor 802. Point 4 represents the expansion valve outlet or low pressure outlet 824 of the rotary liquid compressor 802 (in Figure 3 and Figure 4 denoted by PX in FIG. 8 ) and the evaporator inlet 826. Figure 3 and Figure 4 As shown, compressor 812 increases the pressure and therefore the temperature of the refrigerant working fluid (e.g., carbon dioxide) to a temperature above the environment where it can reject heat to the external, hotter environment. This occurs inside gas cooler 808. Unlike a conventional condenser where the temperature is kept constant by a majority of the heat exchange process inside the two-phase dome on the T-S diagram, in the gas cooler 808 of a transcritical carbon dioxide system, there is no phase boundary because the carbon dioxide is in a supercritical state and the carbon dioxide is above the two-phase dome 828. Therefore, as the carbon dioxide rejects heat to the environment, the temperature drops. The greater the ambient temperature, the greater the pressure ratio on compressor 812 and the greater the pressure of the system. At point 3, the carbon dioxide leaving the gas cooler outlet 830 then passes through an expansion valve (in a refrigeration system having a Joule-Thomson expansion valve) and follows a constant enthalpy process in the valve (3→4 h ), as shown by curve 832. On the P-H diagram 816, curve 832 is a straight vertical line (because it is an isenthalpic process). As a result, the carbon dioxide enters the two-phase dome 828 and becomes an equilibrium mixture of liquid and gas. The exact mass fraction of the liquid is given by 4 h The point at which the liquid carbon dioxide (i.e., curve 832) intersects a constant pressure horizontal line 834 representing the evaporator pressure is determined. The two-phase mixture then continues through the evaporator 810, where the liquid carbon dioxide absorbs more and more heat and becomes a saturated vapor at the outlet 836 of the evaporator 810. Thus, the fluid entering the compressor 818 is in a pure vapor (gas) phase.

[0044] Now consider the case where the Figure 2The system of the rotary pressure exchanger 802 of the Joule-Thomson valve is shown. Figure 3 and Figure 4 As shown, carbon dioxide in a supercritical state at the gas cooler outlet 830 enters the rotary pressure exchanger 802 at the high-pressure inlet 822, undergoes isentropic or near-isentropic (e.g., 85% isentropic efficiency) expansion, and leaves the rotary pressure exchanger 802 at the low-pressure outlet 824 as a two-phase gas-liquid carbon dioxide mixture. This process is shown by the T-S diagram 814 and the curve 835 on the P-H diagram 816. As shown in the figure, the curve 835 (obtained by the rotary pressure exchanger 802) is located on the left side of the curve 832 (obtained by the expansion valve), which means that in the case of expansion through the rotary pressure exchanger 802 (the position of point 4 on the P-H diagram 816), the amount or percentage of liquid content in the two-phase fluid is greater than that in the case of expansion through the rotary pressure exchanger 802 (the position of point 4 on the P-H diagram 816) using the expansion valve. h 800). Due to the greater liquid content, the heat absorption capacity of the refrigerant (e.g., carbon dioxide) in the evaporator 810 is also greater. Therefore, for the same pressure and temperature boundary conditions set by the ambient conditions, the cooling capacity of the refrigeration system 800 increases when the rotary pressure exchanger 802 is used instead of the Joule-Thomson valve. Point 4 s The position on the PH diagram 816 represents a perfect isentropic expansion process (e.g., 100% isentropic expansion efficiency). The two-phase carbon dioxide at point 4 then continues to absorb heat in the evaporator 810 (process 4→1). The length 838 of segment 840 (through 4 h minus 4 definition) is the additional cooling capacity provided by system 800 using rotary pressure exchanger 802 compared to a typical system using a Joule-Thomson expansion valve (the length of segment 834, which is the enthalpy at point 1 and the enthalpy at point 4 h This is one of the key advantages provided by integrating the rotary pressure exchanger 802 into the refrigeration cycle.

[0045] When observing the second fluid flow as superheated gaseous carbon dioxide from the evaporator 80 into the rotary pressure exchanger 802 (at the low pressure inlet 813) and undergoing the process shown by the dashed line 842 (i.e., process 1→2 s), another advantage provided by using the rotary pressure exchanger 802 in the refrigeration cycle becomes apparent when compression is performed isentropically or nearly isentropically (e.g., 85% isentropic efficiency) at a rate of 100 % or less. This process will be similar to the isentropic process 1→2 occurring inside the compressor 812. Since almost all of the compression occurs inside the rotary pressure exchanger 802, in some embodiments, the main compressor 812 can be completely or partially eliminated. For example, in this case, the compressor 812 can be replaced by a very low differential pressure gas blower or circulating pump, which consumes very little work (due to the very small enthalpy change across it). This produces a huge advantage in the efficiency of the refrigeration cycle, as can be seen from the coefficient of performance (COP) equation (i.e., a standard measure of refrigeration cycle efficiency):

[0046]

[0047] Where h is the enthalpy of each of the four points on the P-H diagram 816. As can be seen, when the rotary pressure exchanger 802 is used instead of the conventional combination of the Joule-Thomson valve and the compressor 812, the denominator (h2-h1) in the above equation representing the work (w) done by the compressor 812 (i.e., the power consumed by the compressor 812) becomes very small. This can greatly increase the COP (i.e., efficiency) of the refrigeration cycle. When combined with the first advantage mentioned above (i.e., increased cooling capacity), where h at point 4 is lower than that at point 4 h At h, for a system based on a rotary pressure exchanger, the term (h1-h4) becomes larger, thus further increasing the COP (ie, efficiency) of the refrigeration cycle.

[0048] Figure 5 is a rotary pressure exchanger or a rotary liquid piston compressor 40 (rotary LPC) (e.g. Figure 2802 in FIG. 8 , which is capable of transferring pressure and / or work between a first fluid (e.g., supercritical carbon dioxide circulating in a first fluid circuit 804) and a second fluid (e.g., superheated gaseous carbon dioxide circulating in a second fluid circuit 806) with minimal mixing of the fluids. The rotary LPC 40 may include a generally cylindrical body portion 42 including a sleeve 44 (e.g., a rotor sleeve) and a rotor 46. The rotary LPC 40 may also include two end caps 48 and 50, which include manifolds 52 and 54, respectively. The manifold 52 includes respective inlet ports 56 and outlet ports 58, while the manifold 54 includes respective inlet ports 60 and outlet ports 62. In operation, these inlet ports 56, 60 enable the first fluid and the second fluid to enter the rotary LPC 40 to exchange pressures, while the outlet ports 58, 62 enable the first fluid and the second fluid to subsequently exit the rotary LPC 40. In operation, inlet port 56 can receive a first fluid at a high pressure, and after exchanging pressures, outlet port 58 can be used to direct the first fluid at a low pressure out of the rotating LPC 40. Similarly, inlet port 60 can receive a second fluid at a low pressure, and outlet port 62 can be used to direct the second fluid at a high pressure out of the rotating LPC 40. End caps 48 and 50 include respective end covers 64 and 66 disposed within respective manifolds 52 and 54, which can be in fluid-tight contact with rotor 46. Rotor 46 can be cylindrical and can be disposed within sleeve 44, which enables rotor 46 to rotate about axis 68. Rotor 46 can have a plurality of passages 70 extending substantially longitudinally through rotor 46, the plurality of passages having openings 72 and 74 at each end symmetrically arranged about longitudinal axis 68. The openings 72 and 74 of the rotor 46 are arranged to be in hydraulic communication with the inlet holes 76 and outlet holes 78 in the end cover 64 and the inlet holes 80 and outlet holes 82 in the end cover 66, so that the channel 70 is exposed to the high-pressure fluid and the low-pressure fluid during rotation. As shown, the inlet holes 76 and outlet holes 78 and the inlet holes 80 and outlet holes 82 can be designed in the form of an arc or a segment of a circle (e.g., C-shaped).

[0049] In some embodiments, a controller using sensor feedback (e.g., revolutions per minute measured by a tachometer or optical encoder or volume flow measured by a flow meter) can control the degree of mixing between the first fluid and the second fluid in the rotary LPC 40, which can be used to improve the operability of the fluid handling system. For example, changing the volume flow rate of the first fluid and the second fluid entering the rotary LPC 40 allows an equipment operator (e.g., a system operator) to control the amount of fluid mixed within the rotary liquid piston compressor 10. In addition, changing the rotational speed of the rotor 46 also allows the operator to control mixing. Three features of the rotary LPC 40 that affect mixing are: (1) the aspect ratio of the rotor channel 70, (2) the duration of exposure between the first fluid and the second fluid, and (3) the formation of a fluid barrier (e.g., an interface) between the first fluid and the second fluid within the rotor channel 70. First, the rotor channel 70 is generally long and narrow, which stabilizes the flow within the rotary LPC 40. In addition, the first fluid and the second fluid can move through the channel 70 in a piston flow state with minimal axial mixing. Second, in some embodiments, the speed of the rotor 46 reduces the contact between the first fluid and the second fluid. For example, the speed of the rotor 46 can reduce the contact time between the first fluid and the second fluid to less than about 0.15 seconds, 0.10 seconds, or 0.05 seconds. Third, a small portion of the rotor channel 70 is used for pressure exchange between the first fluid and the second fluid. Therefore, a certain volume of fluid is retained in the channel 70 to serve as a barrier between the first fluid and the second fluid. All of these mechanisms can limit mixing within the rotary LPC 40. In addition, in some embodiments, the rotary LPC 40 can be designed to operate with an internal piston or other barrier that completely or partially isolates the first fluid and the second fluid while achieving pressure transfer.

[0050] Figure 6 9 is an exploded view of an embodiment of a rotary LPC 40 showing the sequence of positions of a single rotor channel 70 in the rotor 46 as the channel 70 rotates through a complete cycle. Note that Figure 6 9 is a simplified diagram of a rotary LPC 40 showing one rotor channel 70, the channel 70 being shown as having a circular cross-sectional shape. In other embodiments, the rotary LPC 40 may include multiple channels 70 having the same or different cross-sectional shapes (e.g., circular, elliptical, square, rectangular, polygonal, etc.). Thus, Figure 6 -9 is a simplification for illustration purposes, and other embodiments of the rotary LPC 40 may have different Figure 6-9. As described in detail below, the rotary LPC 40 promotes pressure exchange between the first fluid and the second fluid by briefly bringing the first fluid and the second fluid into contact with each other within the rotor 46. In certain embodiments, the exchange occurs at a rotational speed that causes limited mixing of the first fluid and the second fluid. More specifically, the speed of the pressure wave passing through the rotor channel 70 (once the channel is exposed to the hole 76), the diffusion rate of the fluid, and the rotational speed of the rotor 46 determine whether any mixing occurs and the extent of the mixing.

[0051] exist Figure 6 , the channel opening 72 is in a first position. In the first position, the channel opening 72 is in fluid communication with the hole 78 in the end cover 64 and is therefore in fluid communication with the manifold 52, while the opposing channel opening 74 is in fluid communication with the hole 82 in the end cover 66 and, by extension, in fluid communication with the manifold 54. As will be discussed below, the rotor 46 can rotate in a clockwise direction indicated by arrow 84. In operation, a low-pressure second fluid 86 passes through the end cover 66 and enters the channel 70, where the low-pressure second fluid 86 contacts the first fluid 88 at a dynamic fluid interface 90. The second fluid 86 then drives the first fluid 88 to exit the channel 70, pass through the end cover 64, and exit the rotary LPC 40. However, due to the short duration of contact, mixing between the second fluid 86 and the first fluid 88 is minimal.

[0052] exist Figure 7 , the passage 70 has been 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 holes 80 and 82 of the end cover 66, and the opening 72 is no longer in fluid communication with the holes 76 and 78 of the end cover 64. Thus, the low pressure second fluid 86 is temporarily contained within the passage 70.

[0053] exist Figure 8 In the channel 70, Figure 7 The position shown is rotated through an arc of approximately 60 degrees. The opening 74 is now in fluid communication with the hole 80 in the end cover 66, and the opening 72 of the channel 70 is now in fluid communication with the hole 76 of the end cover 64. In this position, the high-pressure first fluid 88 enters and pressurizes the low-pressure second fluid 86, thereby driving the second fluid 86 out of the rotor channel 70 and through the hole 80.

[0054] exist Fig. 9 In the channel 70, Figure 6The position shown is rotated through an arc of approximately 270 degrees. In this position, opening 74 is no longer in fluid communication with holes 80 and 82 of end cover 66, and opening 72 is no longer in fluid communication with holes 76 and 78 of end cover 64. Thus, first fluid 88 is no longer pressurized and is temporarily contained within passage 70 until rotor 46 rotates another 90 degrees to begin the cycle again.

[0055] Fig.10 is an exploded view of an embodiment of a rotor 46 having a barrier system 100. As described above, the rotation of the rotor 46 enables pressure transfer between the first fluid and the second fluid. In order to prevent mixing between the first fluid / power fluid and the second fluid / supercritical fluid in the power generation system 4, the rotary liquid piston compressor 10 includes a barrier system 100. As shown, the rotor 46 includes a first rotor section 102 and a second rotor section 104 coupled together. By including the rotor 46 with the first rotor section 102 and the second rotor section 104, the rotor 46 is able to receive and retain the barrier system 100 within the rotor 46. As shown, the first rotor section 102 includes an end face 106 having holes 108 for receiving bolts 110. The bolts 110 pass through these holes 108 and enter holes 112 in the second rotor section 104 to couple the first section 102 and the second section 104 of the rotor 46. The barrier system 100 is placed between the rotor segments 102 , 104 such that the rotor 46 is able to secure the barrier system 100 to the rotor 46 .

[0056] The barrier system 100 may include a plate 114 having a plurality of barriers 116 coupled to the plate 114. The barriers 116 are collapsible membranes that prevent contact / mixing between the first fluid and the second fluid as they exchange pressure in the channel 70 of the rotor 46. As will be discussed below, the barriers 116 expand and contract as pressure is transferred between the first fluid and the second fluid. To couple the plate 114 to the rotor 46, the plate 114 may include a plurality of holes 118 that align with the holes 108 in the first rotor section 102 and the holes 112 in the second rotor section 104. The holes 118 receive the bolts 110 when the first rotor section 102 is coupled to the second rotor section 104 to reduce or prevent lateral movement of the plate 114. In some embodiments, the holes 108 on the first rotor segment 102, the holes 112 on the second rotor segment 104, and the holes 118 on the plate 114 can be placed on one or more diameters (e.g., inner diameter and outer diameter). In this way, the first rotor segment 102 and the second rotor segment 104 can uniformly compress the plate 114 when coupled. In some embodiments, the barriers 116 may not be coupled to or supported by the plate 114. Instead, each barrier 116 can be separately coupled to the rotor 46.

[0057] As shown, the first rotor section 102 defines a length 120 and the second rotor section 104 defines a length 122. By varying the lengths 120 and 122, the rotor 46 enables the barrier system 100 to be placed at different locations in the channel 70 along the length of the rotor 46. In this way, the rotary liquid piston compressor 10 can be adjusted in response to various operating conditions. For example, differences in the density and mass flow rate of the two fluids and the rotational speed of the rotor 46 may affect the extent to which the first fluid and the second fluid can flow into the channel 70 of the rotor 46 to exchange pressure. Therefore, changing the length 120 of the first rotor section 102 and the length 122 of the second rotor section 104 of the rotor 46 can place the barrier system 100 in a position that facilitates pressure exchange between the first fluid and the second fluid (e.g., midway through the rotor 46).

[0058] In some embodiments, the refrigeration system 800 can change the fluids circulating in the first loop 804 and the second loop 806 to resist mixing in the rotary liquid piston compressor 802. For example, the refrigeration system 800 can use an ionic fluid in the first loop 804, which can prevent the diffusion and dissolution of the supercritical fluid with another fluid in a different phase, or in other words, the ionic fluid can prevent mixing with the supercritical fluid. The change of fluids in the refrigeration system 800 can also be used in conjunction with the barrier system 100 to provide redundant resistance to fluid mixing in the rotary liquid piston compressor 802.

[0059] Fig.11 1 is a cross-sectional view of an embodiment of a rotor 46 having a barrier system 100. As described above, the barrier system 100 may include a plate 114 and a barrier 116. These barriers 116 rest within the channel 70 and prevent mixing / contact between the first fluid and the second fluid while still enabling pressure transfer. To facilitate pressure transfer, the barrier 116 expands and contracts. Fig.11As shown, the first barrier 140 of the plurality of barriers 116 is in an expanded position. In operation, when the first fluid 142 flows into the rotor 46 and into the first barrier 140, the first barrier 140 expands. When the first barrier 140 expands, it pressurizes the second fluid 144, driving it out of the rotor 46. At the same time, when the second fluid 144 enters the rotor 46 in preparation for being pressurized, the second barrier 146 can be in a contracted state. The barrier 116 includes a plurality of pleats 148 (e.g., 1, 2, 3, 4, 5 or more) coupled together with the ribs 150. It is these elastic pleats 148 that enable the barrier 116 to expand in volume when the pressurized first fluid 142 flows into the rotor 46. As will be discussed below, the barrier 116 can be made of one or more materials that provide tensile strength, elongation, and chemical resistance to work with supercritical fluids (e.g., carbon dioxide).

[0060] Fig.12 FIG. 4 is a cross-sectional view of an embodiment of a rotor 46 having a barrier system 100. Fig.12 4. As shown, a first barrier 140 of the plurality of barriers 116 is in an expanded position. In operation, when a first fluid 142 flows into the rotor 46 and into the first barrier 140, the first barrier 140 expands. As the first barrier 140 expands, it contacts and pressurizes a second fluid 144, driving it out of the rotor 46. To reduce stress in the barrier 116, the barrier system 100 may include a spring 160. The spring 160 may be coupled to an end 162 (e.g., an end portion, an end face) of the barrier 116 and the plate 114. In operation, the spring 160 stretches as pressure in the barrier 116 increases, and the barrier 116 expands in an axial direction 164. Because the spring 160 absorbs force as the barrier 116 expands, the spring 160 may prevent or reduce over-expansion of the barrier 116. The spring 160 may also increase the life of the barrier 116 because the barrier 116 repeatedly expands and contracts during operation of the power generation system 4. The spring may also provide a more controlled rate of expansion of the barrier 116.

[0061] In some embodiments, the spring 160 can be coupled to an exterior surface 168 of the barrier 116 and / or positioned outside the barrier 116. In other embodiments, the spring 160 can be coupled to an interior surface 170 and / or positioned inside the barrier 116 (i.e., within a membrane of the barrier 116). In other embodiments, the barrier system 100 can include springs 160 positioned both outside and inside the barrier 116. The spring 160 can also be coupled to the rotor 46 instead of the plate 114. For example, the spring 160 can be supported by sandwiching a portion of the spring 160 between the first rotor section 102 and the second rotor section 104 of the rotor 46.

[0062] Fig.13 is a cross-sectional view of an embodiment of a rotor 46 having a barrier system 100. Fig.13 , the barrier system 100 includes a planar barrier 190. As shown, the planar barrier 190 extends across the channel 70 (e.g., in a direction generally intersecting the longitudinal axis of the channel 70), rather than axially into the channel 70 as with the barrier 116 described above. In operation, the planar barrier 190 prevents mixing / contact between the first fluid 142 and the second fluid 144, while still enabling pressure transfer. To facilitate pressure transfer, the planar barrier 190 expands and contracts under pressure. Fig.13 As shown, the first planar barrier 192 of the plurality of planar barriers 190 is in an expanded position. When the first fluid 142 flows into the rotor 46 and into the first planar barrier 192, the first planar barrier 192 expands. When the first planar barrier 192 expands under the pressure of the first fluid 142, the first planar barrier 192 contacts and pressurizes the second fluid 144, driving it out of the rotor 46. When the second fluid 144 enters the rotor 46 in preparation for being pressurized, the second planar barrier 194 may also simultaneously contract. The barrier 116 includes a plurality of pleats 196 (e.g., 1, 2, 3, 4, 5 or more) connected. It is these elastic pleats 148 that expand as the pressurized first fluid 142 flows into the rotor 46 and contract when the pressure is released.

[0063] Fig.14 It is along Fig.11 14-14 of a cross-sectional view of an embodiment of a barrier. Barrier 116 and barrier 190 can be made of one or more materials that provide tensile strength, elongation, and chemical resistance to work with supercritical fluids (e.g., carbon dioxide). For example, barriers 116, 190 can include high stretch ratio elastomeric materials such as ethylene propylene, silicone, nitrile, neoprene, etc. The high stretch ratio capabilities of these materials enable barriers 116, 119 to absorb pressure from the first fluid 142 and transfer it to the second fluid 144. In some embodiments, barriers 116, 119 can include multiple layers (e.g., 1, 2, 3, 4, 5, or more layers) of high stretch ratio materials sandwiched between high strength fabric layers to combine high stretch ratio properties with high strength properties. For example, barriers 116, 119 can include two elastomeric layers 210 overlapping a fabric layer 212. In operation, the elastomeric layer 210 may provide chemical resistance and high stretch ratio capabilities, while the fabric layer 212 may increase the overall tensile strength of the barrier 116 , 190 .

[0064] Fig.15 It is along Fig.1114-14 of a cross-sectional view of an embodiment of a barrier. As described above, the barriers 116, 190 can be made of one or more materials that provide tensile strength, elongation, and chemical resistance to work with supercritical fluids (e.g., the temperature and pressure of the supercritical fluid). In some embodiments, the barriers 116, 119 can include multiple layers (e.g., 1, 2, 3, 4, 5, or more layers) to combine the properties of different materials. For example, the barriers 116, 119 can include two elastomeric layers 210 (e.g., ethylene propylene, silicone, nitrile, neoprene, etc.) overlapping with a fabric layer 212. In operation, the elastomeric layers 210 can provide chemical resistance as well as high stretch ratio capabilities, while the fabric layers 212 increase the tensile strength of the barriers 116, 190. In addition, one or more layers 210 can include a coating 214. The coating 214 can be a chemically resistant coating that resists reaction with the first fluid and / or the second fluid. For example, layer 210 may include a coating 214 on an outermost surface 216 that chemically protects layer 210 from the supercritical fluid.

[0065] Fig.16 2 is a cross-sectional view of an embodiment of a rotary liquid piston compressor 10 (e.g., a rotary LPC) having a cooling system 240 (i.e., a thermal management system). In some embodiments, the cooling system 240 may include a heat exchanger fabricated around the microchannels of the rotary liquid piston compressor. Figure 1 As explained in the description of, fluid changes phase with the change of temperature and pressure.At pressure and temperature higher than critical point, fluid becomes supercritical fluid.Due to the unique properties of supercritical fluid (i.e., liquid-like density and gas-like viscosity), refrigeration system 800 uses fluid (e.g., carbon dioxide) in its supercritical state / phase to refrigerate.By utilizing cooling system 240 to control the temperature in rotary liquid piston compressor 10, cooling system 240 can prevent the phase change from supercritical fluid to gas phase inside rotary liquid piston compressor 802.In addition, cooling system 240 can also promote energy removal when heat is generated during supercritical fluid compression, thereby realizing substantially isothermal compression, which is a more efficient compression mode in thermodynamics.As described above, cooling system 240 can include microchannels, which provide high surface area per unit volume, to promote the heat transfer coefficient between the wall of rotary liquid piston compressor 802 and the cooling fluid circulating through cooling system 240.

[0066] The cooling system 240 includes a cooling jacket 242 around at least a portion of the rotary liquid piston compressor housing 244. The cooling jacket 242 may include a plurality of conduits 246 surrounding the housing 244. These conduits 246 may be micro-conduits with diameters between 0.05 mm and 0.5 mm. By including micro-conduits, the cooling system 240 may increase the cooling surface area to control the temperature of the supercritical fluid in the rotary liquid piston compressor 10. The conduits 246 may be arranged in multiple rows (e.g., 1, 2, 3, 4, 5 or more) and / or multiple columns (e.g., 1, 2, 3, 4, 5 or more). Each conduit 246 may be fluidly coupled to each other conduit 246, or the cooling system 240 may be fluidly coupled to a subset of the conduits 246. For example, each conduit 246 in a row may be fluidly coupled to other conduits 246 in the row, but not to conduits 246 in other rows. In some embodiments, each conduit 246 may be fluidly coupled to other conduits 246 in the same column, but not to conduits 246 in different columns. In some embodiments, the conduit 246 can be enclosed by a housing or cover 247. The housing or cover 247 can be made of a material that isolates and resists heat transfer, such as polystyrene, fiberglass wool, or various types of foam. The flow of the cooling fluid through the conduit 246 can be controlled by a controller 248. The controller 248 may include a processor 250 and a memory 252. For example, the processor 250 may be a microprocessor that executes software to control the operation of the actuator 98. The processor 250 may include multiple microprocessors, one or more "general-purpose" microprocessors, one or more special-purpose microprocessors, and / or one or more application-specific integrated circuits (ASICS) or some combination thereof. For example, the processor 250 may include one or more reduced instruction set (RISC) processors.

[0067] The memory 252 may include volatile memory such as random access memory (RAM) and / or non-volatile memory such as read-only memory (ROM). The memory 252 may store various information and may be used for various purposes. For example, the memory 252 may store processor executable instructions, such as firmware or software, for execution by the processor 250. The memory may include ROM, flash memory, a hard drive, or any other suitable optical, magnetic, or solid-state storage medium, or a combination thereof. The memory may store data, instructions, and any other suitable data.

[0068] In operation, the controller 248 can receive feedback from one or more sensors 254 (e.g., temperature sensor, pressure sensor) that directly or indirectly detect the temperature and / or pressure of the supercritical fluid. Using the feedback from the sensors 254, the controller 248 controls the flow rate of the cooling fluid from the cooling fluid source 256 (e.g., chiller system, air conditioning system).

[0069] Fig.17 is a cross-sectional view of an embodiment of a rotary liquid piston compressor 802 (RLPC) having a heating system 280 (i.e., a thermal management system). In operation, the heating system 280 can control the temperature of a fluid (i.e., a supercritical fluid) circulating through the rotary liquid piston compressor 802. By controlling the temperature, the heating system 280 can prevent or reduce the formation of condensation and / or dry ice due to non-isentropic expansion of the fluid.

[0070] Heating system 280 includes a heating jacket 282 around at least a portion of rotary liquid piston compressor housing 244. Heating jacket 282 may include a plurality of conduits or cables 284 surrounding housing 244. These conduits or cables 284 are capable of temperature control of supercritical fluid. For example, conduit 284 may carry a heating fluid that transfers heat to the supercritical fluid. In certain embodiments, (one or more) cables 284 (e.g., coils) may carry an electric current that generates heat due to the resistance of (one or more) cables 284. Conduit 246 may also be enclosed by housing or cover 286. Housing or cover 286 may be made of materials that isolate and resist heat transfer, such as polystyrene, fiberglass wool or various types of foam.

[0071] The flow of the heating fluid or electric current through the conduit or cable 284 is controlled by the controller 248. In operation, the controller 248 can receive feedback from one or more sensors 254 (e.g., temperature sensors, pressure sensors) that directly or indirectly detect the temperature and / or pressure of the supercritical fluid. For example, the sensor 254 can be placed in direct contact with the supercritical fluid (e.g., in a cavity containing the supercritical fluid). In some embodiments, the sensor 254 can be placed in the housing 244, the sleeve 44, the end caps 64, 66. When the material around the sensor 254 responds to changes in the temperature and / or pressure of the supercritical fluid, the sensor 254 senses the change and transmits the change to the controller 248. The controller 248 then associates it with the temperature and / or pressure of the actual supercritical fluid. Using feedback from the sensor 254, the controller 248 can control the flow rate of the heating fluid from the heating fluid source 288 (e.g., a boiler) through the conduit 284. Similarly, if the heating system 280 is a resistive heating system, the controller 248 may control the current flowing through the cable(s) 284 in response to feedback from the one or more sensors 254 .

[0072] Fig.18 and Fig.19 Two examples of supermarket system architectures 300, 302 are shown, which utilize a transcritical carbon dioxide refrigeration system based on a rotary pressure exchanger rather than conventional Joule-Thomson expansion valve-based cooling. Fig.18), a two-phase low pressure effluent stream (e.g., a carbon dioxide gas / liquid mixture) from a rotary pressure exchanger 304 (via a low pressure outlet 305) passes through a flash tank 306 that separates the gas and liquid phases. The carbon dioxide liquid phase is delivered to low temperature (e.g., about -20 degrees Celsius (C)) and medium temperature (e.g., about -4 degrees Celsius) heat loads / evaporators 308, 310 (e.g., the freezer and refrigerator sections of a supermarket, respectively), where the carbon dioxide liquid phase extracts heat and becomes superheated. Since this is a pure liquid phase, rather than a two-phase gas / liquid phase, it has a greater heat absorption (i.e., cooling) capacity. Flow control valves 312, 314 (e.g., in response to control signals from a controller) can regulate the flow of the liquid carbon dioxide stream to the respective heat loads 308, 310. The superheated carbon dioxide vapor from the freezer zone 308 then enters the cryogenic compressor 316 and is subsequently recombined with the superheated carbon dioxide vapor from the refrigerator zone 310 and the separated superheated gas phase carbon dioxide separated from the gas / liquid mixture in the flash tank 306 at the same pressure. The control valve 318 (e.g., a flash gas control valve) (e.g., in response to a control signal from a controller) can regulate the flow of superheated gaseous carbon dioxide flowing out of the flash tank 306. The recombined superheated gaseous carbon dioxide then enters the rotary pressure exchanger 304 at the low pressure inlet 320 and is compressed to the highest pressure in the system (e.g., about 10,342 kPa (1500 psi) or about 14,479 kPa (2100 psi) depending on system requirements) and converted to supercritical carbon dioxide. The supercritical carbon dioxide leaves the rotary pressure exchanger 304 (via the high pressure outlet 322) and proceeds to the heat exchanger 324 at the highest pressure, where the supercritical carbon dioxide rejects heat to the environment and cools. In certain embodiments, heat exchanger 324 is a gas condenser used with subcritical carbon dioxide. Supercritical carbon dioxide flows from gas cooler 324 to high pressure inlet 326 of rotary pressure exchanger 304. The small boost required to overcome the hydraulic resistance in the system and the small differential pressure in rotary pressure exchanger 304 can be provided by using a small compressor 328 (e.g., a low DP cycle compressor) (as shown, between the paths from rotary pressure exchanger 304 and gas cooler 324), with very little energy consumption compared to conventional compressors.

[0073] Heat exchanger 324 is arranged along high pressure branch, for making high pressure carbon dioxide circulate in supercritical or subcritical state. Low temperature evaporator 308 and low temperature compressor 316 are arranged along low pressure branch, for making low pressure (that is, lower than the pressure in high pressure branch) carbon dioxide circulate in liquid, gaseous or vapor state or two-phase mixture of liquid and vapor. Medium temperature evaporator 310 and valve 314 are arranged along intermediate pressure branch, and this intermediate pressure branch makes refrigerant circulate under intermediate pressure between the corresponding pressure of refrigerant in high pressure branch and low pressure branch. The intermediate pressure of refrigerant in intermediate pressure branch is equal to the saturation pressure at evaporator 310. The refrigerant leaving flash tank 306 and flowing directly to the inlet 320 of rotary pressure exchanger 304 is at intermediate pressure. Therefore, rotary pressure exchanger 304 fluid is connected to intermediate pressure branch and high pressure branch. The rotary pressure exchanger 304 receives the high-pressure refrigerant from the high-pressure branch, receives the intermediate-pressure refrigerant in a vapor state, a liquid state, or a two-phase mixture of liquid and vapor from the intermediate-pressure branch, and exchanges the pressure between the high-pressure refrigerant and the intermediate-pressure refrigerant. A first outflow stream of the high-pressure refrigerant in a supercritical state or a subcritical state and a second outflow stream of the intermediate-pressure refrigerant in a liquid state or a two-phase mixture of liquid and vapor flow out of the rotary pressure exchanger.

[0074] In the second architecture 302 ( Fig.19 ), only the separated gaseous carbon dioxide from the flash tank is re-sent through the rotary pressure exchanger 304 at the low pressure inlet 320 and compressed to the highest pressure in the system. The superheated gaseous carbon dioxide from the freezing zone 308 and the refrigerator zone 310 flows to the low temperature compressor 316 and the medium temperature compressor 330, respectively. The outflow of the low temperature compressor is combined with the superheated gaseous carbon dioxide from the refrigerator zone 310 before the medium temperature compressor 330. The outlet flow of the medium temperature compressor (e.g., supercritical carbon dioxide) is combined with the supercritical carbon dioxide leaving the rotary pressure exchanger 304 (via the high pressure outlet 322), where the supercritical carbon dioxide is combined with the already compressed low and medium temperature compressor outlet flows (superheated gaseous carbon dioxide at the same pressure as the flash tank 306) before advancing through the gas cooler 324. This architecture has advantages in certain refrigeration schemes.

[0075] Heat exchanger 324 is arranged along high pressure branch, and is used for making high pressure carbon dioxide circulate in supercritical or subcritical state. Low temperature evaporator 308 and low temperature compressor 316 are arranged along low pressure branch, and are used for making low pressure (that is, lower than the pressure in high pressure branch) carbon dioxide circulate in liquid, gaseous or vapor state or two-phase mixture of liquid and vapor. Medium temperature evaporator 310 and valve 314 are arranged along first intermediate pressure branch, and this first intermediate pressure branch makes refrigerant circulate under first intermediate pressure, and this first intermediate pressure is between the corresponding pressure of refrigerant in low pressure branch and second intermediate pressure branch. Second intermediate pressure branch is between flash tank 306 and rotary pressure exchanger 304. The first intermediate pressure of refrigerant in intermediate pressure branch is equal to the saturation pressure at evaporator 310. The refrigerant leaving flash tank 306 and flowing directly to inlet 320 of rotary pressure exchanger 304 is at second intermediate pressure, and this second intermediate pressure is between the corresponding pressure of refrigerant in high pressure branch and first intermediate pressure branch. Therefore, the rotary pressure exchanger 304 is fluidly coupled to the second intermediate pressure branch and the high pressure branch. The rotary pressure exchanger 304 receives the high pressure refrigerant from the high pressure branch, receives the second intermediate pressure refrigerant in a vapor state, a liquid state, or a two-phase mixture of liquid and vapor from the second intermediate pressure branch, and exchanges the pressure between the high pressure refrigerant and the second intermediate pressure refrigerant. A first outflow stream of the high pressure refrigerant in a supercritical state or a subcritical state and a second outflow stream of the second intermediate pressure refrigerant in a liquid state or a two-phase mixture of liquid and vapor flow out of the rotary pressure exchanger.

[0076] Fig. 20 5 is a schematic diagram of an embodiment of a control system 570 that controls the movement of a fluid (e.g., supercritical carbon dioxide, superheated gaseous carbon dioxide) in a rotary pressure exchanger or a rotary liquid piston compressor 572. As described above, a rotary liquid piston compressor can be used to exchange energy between two fluids. For example, a rotary liquid piston compressor 572 can be used to exchange energy between two fluids in the above-mentioned refrigeration system. In order to reduce and / or prevent the transfer of superheated gaseous carbon dioxide 574 or a two-phase gas / liquid carbon dioxide mixture 575 in a fluid circuit 576 into a fluid circuit 578 that circulates a working fluid (i.e., superheated carbon dioxide 580), the control system 570 can control the flow rate of the superheated gaseous carbon dioxide 574 into the rotary liquid piston compressor 572 in response to the flow rate of the working fluid 580. That is, by controlling the flow rate of the superheated gaseous carbon dioxide 574, the control system 570 can prevent and / or limit the superheated gaseous carbon dioxide 574 from completely flowing through the rotary liquid piston compressor 572 (i.e., completely flowing through the working fluid 580). Figure 5 channel 70 shown in ) and enters the working fluid circuit 578.

[0077] In order to control the flow rate of the superheated gaseous carbon dioxide 574, the control system 570 includes a valve 582 that controls the amount of superheated gaseous carbon dioxide 574 entering the rotary liquid piston compressor 572. Sensors 586 and 588 sense the respective flow rates of the superheated gaseous carbon dioxide 574 and the working fluid 580 and transmit signals indicative of the flow rates. That is, the sensors 586 and 588 measure the respective flow rates of the superheated gaseous carbon dioxide 574 and the working fluid 580 entering the rotary liquid piston compressor 572. The controller 584 receives and processes the signals from the sensors 586, 588 to detect the flow rates of the superheated gaseous carbon dioxide 574 and the working fluid 580.

[0078] In response to the detected flow rate, the controller 584 controls the valve 582 to prevent and / or reduce the transfer of the superheated gaseous carbon dioxide 574 into the working fluid circuit 578. For example, if the controller 584 detects a low flow rate with the sensor 588, the controller 584 can correlate the flow rate with the extent to which the working fluid enters the rotary liquid piston compressor 572 in the direction 590. The controller 584 can therefore determine a relative flow rate of the superheated gaseous carbon dioxide 574 entering the rotary liquid piston compressor 572 that drives the working fluid 580 out of the rotary liquid piston compressor 572 in the direction 592, rather than driving the superheated gaseous carbon dioxide 574 out of the rotary liquid piston compressor 572 in the direction 592. In other words, the controller 584 controls the valve 582 to ensure that the flow rate of the working fluid 580 entering the rotary liquid piston compressor 572 is greater than the flow rate of the superheated gaseous carbon dioxide 574 to prevent the superheated gaseous carbon dioxide 574 from flowing into the working fluid circuit 578.

[0079] As shown, the controller 584 may include a processor 594 and a memory 596. For example, the processor 594 may be a microprocessor that executes software to process signals from the sensors 586, 588 and control the operation of the valve 582 in response.

[0080] Fig.216 is a schematic diagram of an embodiment of a control system 620 that controls the movement of a fluid (e.g., supercritical carbon dioxide, superheated gaseous carbon dioxide) in a rotary liquid piston compressor 622. As described above, a rotary liquid piston compressor or pump can be used to exchange energy between two fluids. For example, a rotary liquid piston compressor 622 can be used to exchange energy between two fluids in the above-mentioned refrigeration system. In order to reduce and / or prevent the transfer of superheated gaseous carbon dioxide 624 or a two-phase gas / liquid carbon dioxide mixture 625 in a fluid circuit 626 into a working fluid circuit 628 that circulates a working fluid 630 (e.g., supercritical carbon dioxide), the control system 620 can control the distance that the superheated gaseous carbon dioxide travels axially in the rotor channel of the rotary liquid piston compressor 622 in response to the flow rate of the working fluid 630 and the flow rate of the superheated gaseous carbon dioxide 624. The control system 620 controls the movement of the power fluid by slowing down or speeding up the rotation speed of the rotor of the rotary liquid piston compressor 622. That is, by controlling the rotational speed, the control system 620 can prevent and / or limit the superheated gaseous carbon dioxide 624 from completely flowing through the rotary liquid piston compressor 622 (i.e., completely flowing through the rotary liquid piston compressor 622). Figure 5 channel 70 shown in FIG. 6A ) and enters the process fluid circuit 628 .

[0081] To reduce mixing of superheated gaseous carbon dioxide 624 with process fluid 630, control system 620 includes motor 632. Motor 632 controls a rotor (e.g., Figure 5 The rotor 46 (shown in FIG. 4 ) controls the rotational speed of the rotor 46, and therefore controls the axial length of the passageway through which the superheated gaseous carbon dioxide 624 can flow into the rotor. The faster the rotor rotates, the less time the superheated gaseous carbon dioxide and the operating fluid have to flow into the passageway of the rotor, and thus the superheated gaseous carbon dioxide / operating fluid occupies a smaller axial length of the passageway through the rotor. Likewise, the slower the rotor rotates, the longer time the superheated gaseous carbon dioxide and the operating fluid have to flow into the passageway through the rotor, and thus the superheated gaseous carbon dioxide / operating fluid occupies a larger axial length of the passageway through the rotor.

[0082] The control system 620 may include a variable frequency drive for controlling the motor, and sensors 634 and 636 that sense the respective flow rates of the superheated gaseous carbon dioxide 624 and the working fluid 630 and transmit signals indicative of the flow rates. The controller 638 receives and processes the signals to detect the flow rates of the superheated gaseous carbon dioxide 624 and the working fluid 630. In response to the detected flow rates, the controller 638 sends commands to the variable frequency drive, which controls the speed of the motor 632 to prevent and / or reduce the transfer of the superheated gaseous carbon dioxide 624 to the working fluid circuit 578. For example, if the controller 638 detects a low flow rate of the working fluid 630 with the sensor 636, the controller 638 can correlate the flow rate with the extent to which the working fluid has moved in the direction 640 into the passage of the rotary liquid piston compressor 622. Thus, the controller 638 can determine the relative speed of the motor 632 to drive the working fluid 630 out of the rotary liquid piston compressor 622 in the direction 642 rather than driving the superheated gaseous carbon dioxide 624 out of the rotary liquid piston compressor 622 in the direction 642 .

[0083] In response to a low instantaneous flow rate of the working fluid relative to the superheated gaseous carbon dioxide, the controller 638 controls the motor 632 via the variable frequency drive to increase the rotational speed of the rotary liquid piston compressor 622 (i.e., increase the number of revolutions per minute), thereby reducing the axial length that the superheated gaseous carbon dioxide 624 can travel within the passage of the rotary liquid piston compressor 622. Similarly, if the instantaneous flow rate of the working fluid 630 is too high relative to the motive fluid, the controller 638 reduces the rotational speed of the rotary liquid piston compressor 622 to increase the axial length that the superheated gaseous carbon dioxide 624 travels into the passage of the rotary liquid piston compressor 622, thereby driving the working fluid 630 out of the rotary liquid piston compressor 622.

[0084] As shown, the controller 638 may include a processor 644 and a memory 646. For example, the processor 644 may be a microprocessor that executes software to process signals from the sensors 634, 636 and control the operation of the motor 632 in response.

[0085] As described above, since almost all of the compression occurs within the rotary pressure exchanger, in some embodiments, the main compressor 812 (e.g., a bulk compressor) can be completely or partially eliminated. For example, the compressor can be replaced by a very low differential pressure gas blower or circulation pump that consumes very little work (due to the very small enthalpy change across it). Fig.22Ais a schematic diagram of an embodiment of a refrigeration system 900 (e.g., a transcritical carbon dioxide refrigeration system) having a rotary pressure exchanger or rotary liquid piston compressor (LPC) 902 (e.g., having a low flow, high DP leakage pump and a low DP, high flow circulation pump instead of a high flow compressor). In general, the refrigeration system 900 is similar to Figure 2 Refrigeration system 800.

[0086] As shown, the refrigeration system 900 includes a first fluid circuit 904 and a second fluid circuit 906. The first fluid circuit (high pressure circuit) 904 includes a gas cooler or condenser 908, a high pressure, high flow, low DP multiphase circulation pump 909 and the high pressure side of the rotary pressure exchanger 902. The second fluid circuit (low pressure circuit) 906 includes an evaporator 910 (e.g., cooling or heat load), a low pressure, high flow, low DP multiphase circulation pump 911 and the low pressure side of the rotary pressure exchanger 902. The rotary pressure exchanger 902 fluidly connects the high pressure circuit 904 and the low pressure circuit 906. In addition, a multiphase leakage pump 913 running at low flow but high DP takes any leakage from the pressure exchanger 902 at low pressure from the low pressure outlet 920 and pumps it back to the high pressure circuit 904 just upstream of the high pressure inlet 914 of the pressure exchanger 902. The multiphase pump 909 in the high pressure loop 904 ensures that the required flow rate is maintained in the high pressure loop 904 by overcoming the small pressure loss in the loop 904. Because there is not much differential pressure across the pump 909, it consumes very little energy. The flow entering the multiphase pump 909 comes from the outlet 936 of the gas cooler / condenser 908 and can be in a supercritical state, a liquid state, or a two-phase mixture of liquid and vapor. Since there is not much pressure rise across the pump 909, the flow leaving the pump 909 will be in the same state as the incoming flow entering the high pressure inlet 914 of the pressure exchanger 902. The flow from the low pressure outlet 920 of the pressure exchanger 902 can be in a two-phase liquid-vapor state or a pure liquid state.

[0087] The multiphase pump 913 in the low-pressure loop 906 circulates this large amount of low-pressure refrigerant flow through the evaporator 910 and sends it to the low-pressure inlet 918 of the pressure exchanger 902. The multiphase pump 913 also has a very small differential pressure (i.e., just enough to overcome any pressure loss in the system), so the pump 913 consumes very little energy compared to traditional large-flow, high-differential pressure compressors. The low-pressure multiphase pump 913 circulates the flow through the evaporator 910, gains heat in the evaporator 910, and converts itself into a pure vapor state or into a two-phase liquid-vapor mixture with a higher vapor content. The high vapor content flow then enters the low-pressure inlet 918 of the pressure exchanger 902 and is pressurized to a high pressure. According to standard thermodynamic laws, this in turn increases the temperature of the fluid. This high-pressure, high-temperature fluid then leaves the high-pressure outlet 922 of the pressure exchanger 902. The fluid leaving high pressure outlet 922 can be in supercritical state, or can exist with subcritical steam, or exist as a mixture of liquid and steam with high vapor content, depending on how the system is optimized. Then, the high pressure, high temperature refrigerant enters the gas cooler / condenser 908 of high pressure loop 904, and is discharged to the surrounding environment. Through the discharge heat, the refrigerant either cools (if in supercritical state), or changes phase to liquid state. Then, the multiphase pump 909 in the high pressure loop 904 receives the liquid refrigerant and circulates it through the high pressure loop 904, as previously described.

[0088] If there is no internal leakage in the pressure exchanger 902, the high pressure circuit 904 will maintain a constant high pressure, and the low pressure circuit 906 will maintain a constant low pressure. However, if there is an internal leakage from the high pressure side to the low pressure side in the pressure exchanger 902, there will be a net migration of flow from the high pressure circuit 904 to the low pressure circuit 906. In order to take into account this migration and pump this leakage flow back to the high pressure circuit 904, a third multiphase pump 913 is used, which is a high differential pressure, low flow leakage pump. Pump 913 extracts any additional flow leaking into the low pressure circuit 906 at low pressure and pumps it back into the high pressure circuit 904 to maintain the mass balance and pressure in the respective circuits 904, 906. A three-way valve 915 is provided in the low pressure circuit 906 between the low pressure outlet 920 of the pressure exchanger 902 and the inlet of the low pressure multiphase pump 911. The valve 915 is capable of splitting the flow and directing only the excess flow coming out of the low pressure outlet 920 of the pressure exchanger 902 to the high DP multiphase pump 913. Due to the compressibility of the refrigerant, and due to the density differences between the four streams entering and leaving the pressure exchanger 902, the pump 913 is also capable of pumping any additional flow coming out of the low pressure outlet 920. The pump 913 also helps to maintain the pressure of the low pressure circuit 906 at a constant low pressure and the pressure of the high pressure circuit 904 at a constant high pressure. Another three-way valve 917 is provided in the high pressure circuit 904 between the outlet of the high pressure multiphase pump 909 and the high pressure inlet 94 of the pressure exchanger 902. The valve 917 is capable of combining the leakage / excess flow from the high DP multiphase pump 913 with the high pressure bulk flow from the high pressure multiphase pump 909 and then sending it to the high pressure inlet 914 of the pressure exchanger 902. Although the differential pressure across the multiphase pump 913 is high, the flow rate it must pump is small (e.g., approximately 1% to 10% of the total flow rate through either of the other two pumps 909, 911). Therefore, the energy consumption of the pump 913 is also relatively low. When the energy consumption of all three multiphase pumps 909, 911, 913 is added together, it will still be much lower than the energy consumption of a conventional compressor used to pressurize the entire large flow rate from the lowest pressure in the system (i.e., the evaporator pressure) to the highest pressure in the system (i.e., the condenser / gas cooler pressure). This is a major advantage of this configuration.

[0089] Fig. 22B Another embodiment of a refrigeration system 923 without a high flow compressor is shown. It is similar to Fig.22A In the illustrated system 900, any excess flow exiting the low pressure outlet 920 of the pressure exchanger 902 (due to internal leakage of the pressure exchanger 902 or due to differences in compressibility and density of the four flows entering and leaving the pressure exchanger 902 as previously described) is pumped through the evaporator 910 along with the bulk of the low pressure flow and converted to vapor before being compressed back into the high pressure loop 904. Thus, Fig.22A The high DP, low flow multiphase leakage pump 913 is composed of Fig. 22B The high DP, low flow leakage compressor 925 shown is replaced. The leakage compressor 925 compresses the excess flow in the low pressure vapor state to the high pressure vapor state or supercritical state, and then injects it into the high pressure loop 904. Fig.22A The location of this re-injection of excess flow is also different compared to the location in FIG. The vapor or supercritical refrigerant leaving the leaking compressor 925 is injected downstream of the high pressure outlet 922 of the pressure exchanger 902 (at the same pressure as the leaking compressor outlet pressure). Fig. 22B As shown, a three-way valve 927 is disposed downstream of the evaporator 910 so as to be able to divert excess flow from the bulk flow in the low pressure circuit 906 before sending the excess flow through the leakage compressor 925. Similarly, a three-way valve 929 is disposed downstream of the pressure exchanger 902 so as to recombine the high pressure leakage flow leaving the leakage compressor 925 with the high pressure bulk flow leaving the pressure exchanger 922. The combined high pressure flow then proceeds to the gas cooler / condenser 908 as previously described. Fig.22A The advantage of this configuration, compared to the configuration in FIG. 1 , is that it provides additional heat absorption capacity to the cycle due to the additional flow through the evaporator 910 (excess flow from the low pressure outlet 920). Fig.22A Compared to the system 900 shown, the energy consumption of this cycle will be slightly higher because the energy consumed by the leakage compressor 925 will be slightly higher than the energy consumed by the multiphase leakage pump 913. This is because the refrigerant is compressed to a high pressure in the leakage compressor 925 completely in a vapor state, rather than being pumped in the multiphase leakage pump 913 in a partially or completely liquid state.

[0090] Reference Fig.23 and Fig.24 The thermodynamic processes occurring in refrigeration system 923 are described in more detail. Fig.23 and Fig.24 A temperature-entropy (T-S) diagram 926 and a pressure-enthalpy (P-H) diagram 928 are shown to illustrate the thermodynamic processes occurring at the four major components of the refrigeration system 900. Point 1 represents a leaky compressor inlet 930 (see Fig. 22B ). Point 2 represents the leaking compressor outlet 932 and the gas cooler inlet 934. Point 3 represents the gas cooler outlet 936 and the high pressure inlet 914 of the rotary pressure exchanger 902. Point 4 represents the low pressure outlet 920 and the evaporator inlet 938 of the rotary pressure exchanger 902. Fig.23 and 24As shown, the leaking compressor 932 increases the pressure and therefore the temperature of the refrigerant working fluid (e.g., carbon dioxide) to a temperature above the environment where it can reject heat to the external, hotter environment. This occurs within the gas cooler 908. In the gas cooler 908 of a transcritical carbon dioxide system, since the carbon dioxide is in a supercritical state, there is no phase boundary and the carbon dioxide is located above the two-phase dome 940. Therefore, as the carbon dioxide rejects heat to the environment, the temperature drops. Fig.23 and Fig.24 As shown, the carbon dioxide in a supercritical state at the gas cooler outlet 936 enters the rotary pressure exchanger 902 at the high pressure inlet 914 and undergoes isentropic or near isentropic (about 85% isentropic efficiency) expansion and leaves as a two-phase gas-liquid carbon dioxide mixture at the low pressure outlet 920 of the rotary pressure exchanger 902. The two-phase carbon dioxide at point 4 then continues to absorb heat in the evaporator 910 (process 4→1, constant enthalpy process). Overall, diagrams 926 and 928 show the cycle efficiency benefits due to increased cooling capacity and reduced compressor workload. Since the expansion within the rotary pressure exchanger 902 occurs isentropically, it produces an enthalpy change that can be used to compress the fluid coming out of the evaporator 910 to the full high pressure in the system 900. This significantly reduces any work that would have been done by the high-flow compressor, and therefore, it can be replaced by a leaky compressor 925 (which consumes significantly less energy).

[0091] Fig.25 Schematic diagram of a refrigeration system 931 using a low DP recirculation compressor instead of a recirculation pump. The recirculation compressor overcomes the minimum pressure loss in the system 931 by maintaining fluid flow throughout the system 900. Fig.22A and Fig. 22B The difference between the systems 900 and 923 shown in is that the large flow circulation in the low-pressure circuit 906 and the high-pressure circuit 904 is achieved using a low-DP circulation compressor instead of a low-DP multiphase circulation pump. In addition, the positions of these circulation compressors are different. For example, the circulation compressor 941 in the low-pressure circuit 904 (compressor 1) is positioned downstream of the evaporator 910, where it circulates the refrigerant in a vapor state. Similarly, the circulation compressor 944 in the high-pressure circuit 904 (compressor 2) is positioned downstream of the high-pressure outlet 922 of the pressure exchanger 902, where it circulates the refrigerant in a supercritical state or in a high-pressure vapor state. Compressor 3 is similar to reference Fig. 22BA high DP, low flow leakage compressor 925 is described, wherein the compressor 925 will extract the excess flow (e.g., leakage flow from the pressure exchanger 902) in the vapor state entering the low pressure loop 904 from the pressure exchanger 902 and compress it into a high pressure vapor state or supercritical state back to the high pressure loop 904. This excess flow is then combined with the high pressure large flow coming out of the compressor 944 before entering the gas cooler / condenser 934. A low DP circulation compressor 941 disposed along the second fluid loop 906 (e.g., the low pressure fluid loop) maintains fluid flow along the loop 906 (e.g., between the rotary pressure exchanger 902 and the gas cooler 908). In addition, a low DP circulation compressor 944 disposed along the first fluid loop 904 (e.g., the high pressure fluid loop) maintains fluid flow along the loop 904 (e.g., between the evaporator 910 and the rotary pressure exchanger 902). In some embodiments, the refrigeration system 931 may include only compressors 925 and 941. In certain embodiments, refrigeration system 900 may include only compressors 944 and 941. In certain embodiments, each of compressors 941, 944 has a differential pressure thereacross that is significantly less than the differential pressure of leaking compressor 925, as noted in more detail below.

[0092] In some embodiments, a three-way valve is provided at the connection between the flows leaving compressors 925, 944 (e.g., near Fig.25 2 in the circle in the figure). The three-way valve is arranged between the high-pressure, high-flow, low-DP circulating compressor 944 in the high-pressure branch 904 and the gas cooler or condenser, wherein, during the operation of the refrigeration system 931, the first flow from the high-DP, low-flow leakage compressor 925 is combined with the large flow leaving the high-pressure, high-flow, low-DP circulating compressor 944 before advancing to the inlet 934 of the gas cooler or condenser 908. The high-pressure, high-flow, low-DP circulating compressor 944 is arranged between the high-pressure outlet 922 of the rotary pressure exchanger 902 and the three-way valve.

[0093] In addition, in some embodiments, another three-way valve is provided at the downstream connection of the evaporator 910 branching toward the compressors 925, 941 (e.g., near Fig.25 1 in the circle in the figure). The three-way valve is arranged between the evaporator 910 and the rotary pressure exchanger 902 in the low-pressure branch 906, wherein, during the operation of the refrigeration system 931, a part of the flow leaving the evaporator 910 is diverted to the inlet of the high DP, low flow leakage compressor 925 through the three-way valve, and the remaining part of the flow is forwarded to the low-pressure inlet 918 of the rotary pressure exchanger 902. The low-pressure, high-flow, low-DP circulating compressor is arranged between the three-way valve and the low-pressure inlet of the rotary pressure exchanger 902.

[0094] In a conventional refrigeration system (i.e., a transcritical carbon dioxide refrigeration system), a high-flow compressor operates at a flow rate of approximately 113.56 liters (30 gallons) per minute and a differential pressure of approximately 10,342 kPa (1,500 psi). Assuming these operating conditions, the high-flow compressor will require approximately 45,000 (i.e., 30 times 1,500 psi) units of power (i.e., work done or energy consumed). In the above-described refrigeration system 900, low-DP cycle compressor 941 and low-DP cycle compressor 944 (assuming each operates at a flow rate of approximately 113.56 liters (30 gallons) per minute and a differential pressure of approximately 68.9 kPa (10 psi)) will each require approximately 300 (i.e., 30 times 10) units of power. The leaking compressor 925 (assuming it is operating at a flow rate of approximately 5.68 liters (1.5 gallons) and a differential pressure of approximately 10,342 kPa (1,500 psi)) will require approximately 2,250 (i.e., 1.5 times 1,500) units of power. Therefore, the compressors 925, 941, 944 in the refrigeration system 931 will require approximately 2850 units of power. Thus, the compressors 925, 941, 944 will reduce energy consumption by at least 10 times (and even up to 15 times) compared to a system based on a high-flow compressor.

[0095] In certain embodiments, a refrigeration system 931 (having a leaking compressor 925 and one or more low DP cycle compressors 941, 944) may be used for the above Fig.18 and 19 The supermarket architecture described in .

[0096] Fig.26 and 27 Two examples of supermarket system architectures 950, 952 are shown, which utilize a transcritical CO2 refrigeration system based on a rotary pressure exchanger, which also utilizes a conventional Joule-Thomson expansion valve 954. In general, except for the use of the expansion valve 954, the architecture is similar to Fig.18 and Fig.19 In addition, although the architectures 950, 952 are discussed with reference to using a gas cooler for a heat exchanger 324 used with a supercritical refrigerant (e.g., carbon dioxide), the architectures 950, 952 can be used with a condenser as a heat exchanger 324 used with a subcritical refrigerant (e.g., carbon dioxide). In the first architecture 950 ( Fig.26), the two-phase, low-pressure outflow stream (e.g., a carbon dioxide gas / liquid mixture at a first intermediate pressure, e.g., 370 psi) from the rotary pressure exchanger 304 (via the low-pressure outlet 305) passes through a flash tank 306, which separates the gas phase and the liquid phase (both leaving the flash tank at, e.g., 370 psi). The carbon dioxide liquid phase is transported to low-temperature (e.g., about -20 degrees Celsius (C)) and medium-temperature (e.g., about -4 degrees Celsius) heat loads / evaporators 308, 310 (e.g., the freezer and refrigerator sections of a supermarket, respectively), where the carbon dioxide liquid phase extracts heat and becomes superheated. Since this is a pure liquid phase, rather than a two-phase gas / liquid phase, it has a greater ability to absorb heat (i.e., cool). The carbon dioxide liquid phase enters the medium-temperature evaporator 310 at, e.g., 370 psi, while the carbon liquid phase enters the low-temperature evaporator 308 at, e.g., 180 psi after flowing through a flow control valve 312. Flow control valve 312 (e.g., in response to a control signal from a controller) can regulate the flow of liquid carbon dioxide to evaporator 308. Superheated carbon dioxide vapor from freezer zone 308 (at a low pressure of 180 psi) then proceeds to cryogenic compressor 316 (where it exits at a pressure of, for example, 370 psi) and is subsequently recombined with superheated carbon dioxide vapor from refrigerator zone 310 (at a pressure of, for example, 370 psi) and separated superheated gaseous carbon dioxide separated from the gas / liquid mixture in flash tank 306 at the same pressure. Control valve 318 (e.g., flash gas control valve) (e.g., in response to a control signal from a controller) can regulate the flow of superheated gaseous carbon dioxide out of flash tank 306. The recombined superheated gaseous carbon dioxide then enters rotary pressure exchanger 304 at low pressure inlet 320 and is compressed to a second intermediate pressure (e.g., 500 psi). The superheated gaseous carbon dioxide (via the high pressure outlet 322) leaves the rotary pressure exchanger 304 and proceeds to the medium temperature compressor 330, where it is compressed to the highest pressure in the system (e.g., 1300 psi depending on the system requirements) and converted to supercritical carbon dioxide. The supercritical carbon dioxide then proceeds to the heat exchanger 324 (e.g., gas cooler) at the highest pressure, where the supercritical carbon dioxide discharges heat to the environment and cools down. In certain embodiments, the heat exchanger 324 is a gas condenser used with subcritical carbon dioxide. The supercritical carbon dioxide (e.g., 1300 psi) flows from the gas cooler 324 through the high pressure Joule-Thomson valve 954, where the supercritical carbon dioxide is converted into a carbon dioxide gas / liquid mixture (e.g., at a second intermediate pressure, e.g., 500 psi). The carbon dioxide gas / liquid mixture flows into the high pressure inlet 326 of the rotary pressure exchanger 304.

[0097] Fig. 27The architecture 952 in Fig.26 The architecture 950 in is slightly different. Specifically, Fig. 27 As shown, the carbon dioxide gas / liquid mixture (at a second intermediate pressure, such as 500 psi) flows into the flash tank 306 to be separated into pure carbon dioxide gas or vapor and liquid. The carbon dioxide gas from the flash tank 306 flows into the high pressure inlet 326 of the rotary pressure exchanger 304, while the carbon dioxide liquid from the flash tank flows into the low pressure, entering the low temperature evaporator 308 and the medium temperature evaporator 310. The two-phase gas-liquid CO2 mixture leaving the low pressure outlet 305 of the pressure exchanger 304 leaves at the same pressure as the medium temperature evaporator 310, and is combined with the fluid flow leaving the medium temperature evaporator 310 and the low temperature compressor 316 before entering the low pressure inlet 320 of the pressure exchanger 304. In addition, a flow control valve 314 is provided upstream of the medium temperature evaporator 310.

[0098] Specific embodiments are shown herein by way of example in the accompanying drawings and are described in detail, and the present invention may have various modifications and alternative forms. However, it should be understood that the present invention is not intended to be limited to the disclosed specific forms. Rather, the present invention covers all modifications, equivalents and alternatives that fall within the spirit and scope of the present invention as defined by the following appended claims.

Claims

1. A refrigeration system, comprising: A rotary pressure exchanger, comprising: A rotor, wherein the rotor forms a plurality of channels, and the rotor is configured to: receiving a first fluid from a gas cooler or condenser into one or more of the channels from a first inlet of the rotary pressure exchanger; receiving a second fluid from an evaporator from a second inlet of the rotary pressure exchanger into at least one of the channels; and exchanging pressure between the first fluid and the second fluid; a first outlet configured to output the first fluid in a liquid state or a two-phase mixture of liquid and vapor; and a second outlet configured to output the second fluid in a supercritical state or a subcritical state, The refrigeration system enables the refrigeration system to operate more efficiently by increasing the cooling capacity of the refrigeration system.

2. The refrigeration system according to claim 1, characterized in that: The rotary pressure exchanger further comprises a housing, and wherein the rotor and the one or more sensors are disposed within the housing.

3. The refrigeration system according to claim 2, characterized in that: The first inlet receives the first fluid at a first flow rate based on sensor data from the one or more sensors.

4. The refrigeration system according to claim 2, characterized in that: The second inlet receives the second fluid at a second flow rate based on sensor data from the one or more sensors.

5. The refrigeration system according to claim 2, characterized in that: The one or more sensors include one or more of a temperature sensor or a pressure sensor.

6. The refrigeration system according to claim 1, characterized in that: The first fluid and the second fluid are carbon dioxide.

7. The refrigeration system according to claim 1, characterized in that: The second inlet is further configured to receive the second fluid from a flash tank via a flash gas control valve, wherein the first inlet is configured to receive the first fluid at a first pressure, and wherein the second inlet is configured to receive the second fluid at a second pressure less than the first pressure.

8. A refrigeration system comprising: Memory; as well as A processor is coupled to the memory, the processor being configured to: receiving sensor data from a plurality of sensors; controlling a first flow rate of a first fluid from a gas cooler or condenser to a rotary pressure exchanger based on at least a first portion of the sensor data; and controlling a second flow rate of a second fluid from an evaporator to the rotary pressure exchanger based on at least a second portion of the sensor data, wherein the rotary pressure exchanger includes a rotor forming a plurality of channels, and wherein the rotor is configured to: receiving the first fluid from the gas cooler or the condenser into one or more of the channels from a first inlet of the rotary pressure exchanger; receiving the second fluid from the evaporator from a second inlet of the rotary pressure exchanger into at least one of the channels; and exchanging pressure between the first fluid and the second fluid, wherein the first fluid leaves the rotary pressure exchanger in a liquid state or in the form of a two-phase mixture of liquid and vapor, and wherein the second fluid leaves the rotary pressure exchanger in a supercritical state or in a subcritical state, The system enables the system to operate more efficiently by increasing the cooling capacity of the system.

9. The refrigeration system according to claim 8, characterized in that: The plurality of sensors include one or more of a temperature sensor or a pressure sensor.

10. The refrigeration system according to claim 8, characterized in that: At least one of the plurality of sensors is disposed in a housing of the rotary pressure exchanger.

11. The refrigeration system according to claim 8, characterized in that: The processor controls the first flow rate and the second flow rate via one or more valves.

12. The refrigeration system according to claim 8, characterized in that: The first fluid and the second fluid are carbon dioxide.

13. The refrigeration system according to claim 8, characterized in that: The processor also controls a third flow rate of the second fluid from a flash tank to the rotary pressure exchanger via a flash gas control valve.

14. The refrigeration system according to claim 13, characterized in that: The first fluid at the first flow rate enters the rotary pressure exchanger at a first pressure, and wherein the second fluid at the second flow rate and the third flow rate combine to enter the rotary pressure exchanger at a second pressure less than the first pressure.

15. A refrigeration method, comprising: receiving sensor data from a plurality of sensors; controlling a first flow rate of a first fluid from a gas cooler or condenser into a rotary pressure exchanger based on at least a first portion of the sensor data; and controlling a second flow rate of a second fluid from an evaporator to the rotary pressure exchanger based on at least a second portion of the sensor data, wherein the rotary pressure exchanger includes a rotor forming a plurality of channels, and wherein the rotor is configured to: receiving the first fluid from the gas cooler or the condenser into one or more of the channels from a first inlet of the rotary pressure exchanger; receiving the second fluid from the evaporator from a second inlet of the rotary pressure exchanger into at least one of the channels; and exchanging pressure between the first fluid and the second fluid, wherein the first fluid leaves the rotary pressure exchanger in a liquid state or in the form of a two-phase mixture of liquid and vapor, and wherein the second fluid leaves the rotary pressure exchanger in a supercritical state or in a subcritical state, The method enables a cooling system to operate more efficiently by increasing the cooling capacity of the cooling system.

16. The refrigeration method according to claim 15, characterized in that: The plurality of sensors include one or more of a temperature sensor or a pressure sensor.

17. The refrigeration method according to claim 15, characterized in that: At least one of the plurality of sensors is disposed in a housing of the rotary pressure exchanger.

18. The refrigeration method according to claim 15, characterized in that: Control of the first flow rate and the second flow rate is performed via one or more valves.

19. The refrigeration method according to claim 15, characterized in that: The first fluid and the second fluid are carbon dioxide.

20. The refrigeration method according to claim 15, characterized in that: Also included is controlling a third flow rate of the second fluid from the flash tank to the rotary pressure exchanger via a flash gas control valve, wherein the first fluid at the first flow rate enters the rotary pressure exchanger at a first pressure, and wherein the second fluid at the second flow rate and the third flow rate combine to enter the rotary pressure exchanger at a second pressure less than the first pressure.

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