Transcritical Refrigeration System with Gas Cooler Assembly

Abstract

The transcritical refrigeration system includes at least one primary compressor, at least one heat recovery circuit, and at least one gas cooler assembly, wherein the at least one primary compressor is configured to increase the pressure and temperature of a carbon dioxide (CO2) refrigerant to a first refrigerant temperature, the at least one heat recovery circuit is downstream of the at least one primary compressor and configured to absorb at least a first amount of heat from the CO2 refrigerant to reduce the temperature of the CO2 refrigerant to a second refrigerant temperature, and the at least one gas cooler assembly is downstream of the at least one heat recovery circuit. The at least one gas cooler assembly comprises at least one gas cooler-condenser, at least one evaporator, and an expansion valve, the at least one gas cooler-condenser including an inlet and an outlet, the inlet configured to receive the CO refrigerant at the second refrigerant temperature, the at least one evaporator including an inlet and an outlet, the inlet fluidly connected downstream of the outlet of the at least one gas cooler-condenser, and the expansion valve disposed upstream of the inlet of the at least one evaporator.

Description

[Technical Field]

[0001] The disclosed subject matter relates to refrigeration systems, and more particularly to simultaneous heating and cooling refrigeration systems. [Background technology]

[0002] Heat pumps are an efficient alternative to furnaces, boilers, chillers, and air conditioners for heating and cooling buildings. To heat a primary environment, a heat pump must absorb heat from a secondary environment. This requires a refrigeration system to create a temperature difference between the secondary environment and the ambient temperature. Heat pump heating systems designed for high discharge temperatures typically cannot utilize all of the waste heat and must reject some of it to the secondary environment or another environment outside the system. This rejected energy is wasted, especially if the system is actively extracting heat from the secondary environment. Therefore, there is a need for more efficient systems. Summary of the Invention

[0003] The transcritical refrigeration system includes at least one primary compressor, at least one heat recovery circuit, and at least one gas cooler assembly, wherein the at least one primary compressor is configured to increase the pressure and temperature of a carbon dioxide (CO2) refrigerant to a first refrigerant temperature, the at least one heat recovery circuit is downstream of the at least one primary compressor and configured to absorb at least a first amount of heat from the CO2 refrigerant to reduce the temperature of the CO2 refrigerant to a second refrigerant temperature, and the at least one gas cooler assembly is downstream of the at least one heat recovery circuit.

[0004] The at least one gas cooler assembly comprises at least one gas cooler-condenser, at least one evaporator, and an expansion valve, the at least one gas cooler-condenser including an inlet and an outlet, the inlet configured to receive the CO refrigerant at the second refrigerant temperature, the at least one evaporator including an inlet and an outlet, the inlet fluidly connected downstream of the outlet of the at least one gas cooler-condenser, and the expansion valve disposed upstream of the inlet of the at least one evaporator.

[0005] A method of operating a transcritical refrigeration system includes using at least one primary compressor to increase the pressure and temperature of a carbon dioxide (CO2) refrigerant to a first refrigerant temperature; circulating the CO2 refrigerant at the first refrigerant temperature through at least one heat recovery circuit and rejecting heat to the at least one heat recovery circuit to reduce the temperature of the CO2 refrigerant to a second refrigerant temperature; circulating the CO2 refrigerant at the second refrigerant temperature through at least one gas cooler-condenser of a gas cooler assembly; drawing an external air stream at a first air temperature across the at least one gas cooler-condenser to reduce the temperature of the CO2 refrigerant to a third refrigerant temperature and increase the air temperature of the external air stream to a second air temperature. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a schematic diagram of a transcritical refrigeration system including a gas cooler assembly. [Figure 2A] FIG. 2A is a schematic diagram of a first embodiment of a gas cooler assembly. [Figure 2B] FIG. 2B is a schematic diagram of a second embodiment of a gas cooler assembly. [Figure 3] FIG. 3 is a schematic diagram of an alternative embodiment of a transcritical refrigeration system for operation in low ambient conditions.

[0007] While the above-identified figures depict one or more embodiments of the present disclosure, other embodiments are contemplated as noted in the discussion. In all cases, the present disclosure presents the invention by way of illustration and not limitation. It should be understood that numerous other modifications and embodiments may be devised by those skilled in the art which fall within the scope and spirit of the principles of the present invention. The figures may not be drawn to scale, and applications and embodiments of the present invention may include features and components not specifically shown in the drawings. DETAILED DESCRIPTION OF THE INVENTION

[0008] FIG. 1 is a schematic diagram of a refrigeration system 10. The refrigeration system 10 operates in a transcritical state using R-744 carbon dioxide (CO2) refrigerant as the working fluid. Therefore, the refrigeration system 10 can be considered a transcritical refrigeration system. The critical point of the R-744 CO2 refrigerant is 87.8°F (31°C), 1070 psia (7.4 x 10 3 kPa). The various components of the refrigeration system 10 are described herein with reference to a refrigeration cycle.

[0009] The refrigeration system 10 includes primary compressors 12 forming a first suction group for compressing a refrigerant to increase its pressure and temperature. In the illustrated embodiment, there are two primary compressors 12; however, there may be a single primary compressor 12, and in alternative embodiments, there may be two or more (e.g., four) primary compressors 12. In one example, the temperature of the compressed refrigerant ranges from approximately 90°F to 325°F (32.2°C to 162.8°C) so that the refrigerant is supercritical. The primary compressors 12 may be medium-temperature compressors with a low suction temperature threshold of approximately 0°F (-17.8°C). One liquid accumulator 14 is fluidly connected to each primary compressor 12. The liquid accumulator 14 functions as a safety device to prevent liquid droplets entrained in the suction gas from entering the primary compressors 12. In alternative embodiments, a single liquid accumulator 14 may be fluidly connected to multiple primary compressors 12. After compression, the refrigerant passes through an oil separator 16 located downstream of the compressor 12 along a discharge line 18. The oil separator 16 removes oil and other contaminants from the compressed refrigerant, which may be collected in an oil receiver 20. The oil separator 16 may be bypassed in certain situations, such as to perform maintenance.

[0010] Downstream of the oil separator 16 along the discharge line 18 are first and second heat recovery circuits 22, 24, respectively. The first heat recovery circuit 22 may include a heat exchanger 26 through which the refrigerant, at a temperature of approximately 90°F to 325°F, can reject heat to the working fluid (e.g., water, glycol-water mixtures, etc.) of an associated system requiring higher temperatures, such as a boiler (e.g., steam, electric, hot water, etc.), a hot water heater, a floor heating system, a district heating system, a thermal mass storage system, a phase change material (PCM) storage system, etc. Thus, the refrigerant exits the first heat recovery circuit 22 at a reduced temperature ranging from 88°F to 300°F (31.1°C to 148.9°C), depending on the refrigerant temperature entering the first heat recovery circuit 22 and the extent of heat exchange with the working fluid of the circuit. A second heat recovery circuit 24 may optionally be included in the refrigeration system 10 and similarly includes a heat exchanger 28 through which the reduced-temperature refrigerant, between 88°F and 300°F, can reject heat to an associated system working fluid, such as any of those listed above for the first heat recovery circuit 22. Thus, the second heat recovery circuit 24 further reduces the temperature of the refrigerant to approximately 88°F to 290°F (31.1°C to 143.3°C). The heat exchangers 26, 28 may be brazed plate heat exchangers, shell-and-tube heat exchangers, and / or coaxial heat exchangers, to name a few non-limiting embodiments. Bypass valves 30 at the inlet of each of the heat recovery circuits 22, 24 allow one or both circuits to be bypassed depending on the operating mode of the refrigeration system 10.

[0011] Downstream of the heat recovery circuits 22, 24 is a gas cooler assembly 32. The gas cooler assembly 32 includes a bypass valve 31, a gas cooler-condenser 34, an evaporator 36, an expansion valve 38, an adiabatic precooler 40, and a fan 42. The bypass valve 31 is disposed upstream of the gas cooler assembly 32 and is operable to block refrigerant flow to the gas cooler-condenser 34 in a bypass state. In such a state, the refrigerant is bypassed to a liquid receiver 44. The evaporator 36 is fluidly connected to the gas cooler-condenser 34 and is downstream of the gas cooler-condenser 34, interposed by various components described below. As described in more detail below with respect to FIGS. 2A and 2B, an optional damper 71 may be included in the gas cooler assembly 32 to allow supplemental heat to enter the gas cooler assembly. The refrigerant circulates through the gas cooler-condenser 34 and is discharged at a reduced temperature. Accordingly, the liquid receiver 44 is disposed downstream of the gas cooler-condenser 34 to receive the refrigerant. After a pressure drop from the high-pressure control valve 53, liquefied refrigerant collects at the bottom of the liquid receiver 44, and gaseous refrigerant (i.e., "flash gas") is extractable along the parallel compressor suction line 46 and supplied to a parallel compressor 48, a flash gas compressor arranged in parallel with the primary compressor 12, which rises to the top of the liquid receiver 44 where it compresses the gaseous refrigerant for recirculation via the discharge line 18. The parallel compressors 48 may similarly be fluidly connected to a liquid accumulator 50 to prevent liquid from entering each parallel compressor 48. Alternative embodiments may include more than one parallel compressor 48. An intermediate heat exchanger 52 may optionally be disposed along the suction line 46 to superheat the suction flash gas and further subcool the liquid refrigerant.

[0012] A line 54 fluidly connects the liquid receiver 44 to the evaporator 36 of the gas cooler assembly 32 via an expansion valve 38. The expansion valve 38 reduces the pressure and temperature of the refrigerant upstream of the evaporator 36. The refrigerant circulates through the evaporator 36, exits the evaporator 36 along a primary compressor suction line 56, and returns to the primary compressor 12. At least a portion of the liquefied refrigerant from the liquid receiver 44 can be supplied to an optional refrigeration circuit 58. An expansion valve 60 reduces the temperature and pressure of the liquefied refrigerant, which then circulates through a heat exchanger 62 in the refrigeration circuit 58 to absorb heat from and cool the working fluid of a chiller, cooler, freezer, chilled water system, refrigeration system, or related system used to cool commercial, industrial, or residential spaces, server rooms, data centers, medical facilities, indoor agriculture, thermal mass storage systems, PCM storage systems, or food, pharmaceuticals, etc. The refrigerant circulating through the refrigeration circuit 58 can be returned to the primary compressor 12 along the primary suction line 56. Thus, system 10 can advantageously operate in simultaneous heating and cooling modes such that heat recovery circuits 22 and / or 24 and cooling circuit 58 are energized and operate to exchange heat without the need for flow reversing valves to change the direction of flow through system 10.

[0013] Gas cooler assembly 32 may be configured as a horizontal assembly (as shown in FIG. 1) or a V-bank assembly. Figure 2A is a schematic diagram of gas cooler assembly 32A, and Figure 2B is a schematic diagram of an alternative gas cooler assembly 32B, each shown isolated from the rest of refrigeration system 10. Figures 2A and 2B are described below with continued reference to FIG. 1.

[0014] Referring initially to FIG. 2A, the gas cooler assembly 32A is shown as a horizontal gas cooler assembly with various subcomponents stacked along the y-axis to receive fluid flow along the x-axis. If the various components were rotated 90° in either direction so that they were instead stacked along the x-axis, the gas cooler assembly could alternatively be a vertical gas cooler assembly. The gas cooler-condenser 34A is fluidly connected to the discharge line 18 and receives refrigerant at inlet 64A after circulation through the heat recovery circuits 22, 24 (if included and not bypassed) and discharges the refrigerant at outlet 66A. In an exemplary mode of operation, the refrigerant temperature entering inlet 64A can range from 88°F to 300°F. Such an inlet temperature can be achieved, for example, by circulating the refrigerant through only a single heat recovery circuit (e.g., the first heat recovery circuit 22). While the refrigerant circulates through the gas cooler assembly 32A, a fan 42A blows external (i.e., outdoor) airflow F through the gas cooler assembly 32A. E The adiabatic precooler 40A may be operated to draw in the incoming airflow F via the evaporative means when the temperature of the incoming airflow is above a threshold condition. E Therefore, the adiabatic precooler 40A may include an adiabatic cooling pad or a nozzle mist system. E As it flows through gas cooler-condenser 34A, it absorbs heat from the refrigerant circulating through gas cooler-condenser 34A when a temperature difference exists between the two fluids. In this way, the gas cooler-condenser operates as a heat exchanger, operating in series with the upstream heat exchangers 26 and 28. In an example with a relatively low outdoor temperature of 10°F to 20°F (-12.2°C to -6.7°C) and a refrigerant temperature of 88°F to 300°F in gas cooler-condenser 34A, airflow F E absorbs heat from the refrigerant and E , a relatively warm microclimate can be created downstream of the gas cooler-condenser 34A and upstream of the evaporator 36A (i.e., in the space between them). EThe refrigerant passes through the evaporator 36A before being exhausted by the fan 42A and returned to the external environment, often at a higher temperature than when it was taken into the gas cooler assembly 32A. Under certain microclimate conditions, the bypass valve 31 (FIG. 1) can be operated to bypass the refrigerant to the liquid receiver 44. Such conditions may include when the microclimate capacity (i.e., temperature) exceeds an upper threshold, or when 100% of the available heat has been extracted from the refrigerant and no further heat rejection is required.

[0015] The evaporator 36A includes an inlet 68A and an outlet 70A. The expansion valve 38A is located upstream of the inlet 68A. As described above, the refrigerant from the liquid receiver 44 is cooled and expanded by the expansion valve 38A. In one example, the liquid refrigerant may be cooled by the expansion valve 38A from approximately 90°F (32.2°C) to less than 32°F (0°C). A relatively warm airflow F from the microclimate downstream of the gas cooler-condenser 34A is introduced into the evaporator 36A. E rejects an amount of heat to the refrigerant circulating through the evaporator 36A such that the refrigerant is discharged generally above the lower suction temperature threshold of the primary compressor 12 (i.e., 0°F), and in the exemplary embodiment, generally above 32°F (0°C). E The microclimate created by the relatively warm airflow rejects heat to the evaporator 36A, maintaining the ambient temperature above the freezing point of water (i.e., 32°F), thus preventing frost formation downstream on the evaporator 36A. The gas cooler assembly 32A may optionally include a damper 71A fluidly connected to an auxiliary / waste heat source from a separate system. The damper 71A is operable to admit auxiliary heat into the microclimate space between the gas cooler-condenser 34A and the evaporator 36A.

[0016] 2B, gas cooler assembly 32B is shown as a V-bank gas cooler assembly having two sets of subcomponents arranged generally symmetrically about midline M, with gas cooler-condenser 34B and evaporator 36B angled relative to midline M to form a "V." Gas cooler assembly 32B may alternatively be an angled gas cooler assembly having only one set of subcomponents on each side of midline M. Gas cooler assembly 32B is substantially similar to gas cooler assembly 32A, in that refrigerant is supplied to inlet 64B of gas cooler-condenser 34B and discharged through outlet 66B. Evaporator 36B includes an inlet 68B to which cooled refrigerant is supplied via expansion valve 38B. Refrigerant is discharged through outlet 70B of evaporator 36B. Fan 42B generates airflow F E An external airflow F passes across the adiabatic precooler 40B, the gas cooler-condenser 34B, and the evaporator 36B before being exhausted to the external environment. E The gas cooler-condenser 34B is similarly configured to create a microclimate to prevent frost buildup on the evaporator 36B. The gas cooler assembly 32B may also optionally include a damper 71B to pass supplemental heat to the microclimate space between each gas cooler-condenser 34B and the evaporator 36B.

[0017] Returning to FIG. 1 , in some operating modes, frost may form and be detected on the evaporator 36. In such a case, the refrigeration system 10 may initiate the first step of a defrosting sequence, which operates the gas cooler-condenser 34 at maximum exhaust gas temperature, increasing heat rejection capacity and raising the microclimate temperature above 32°F to defrost the evaporator 36. If step 1 alone is not sufficient to defrost the evaporator 36, step 2 may be initiated. At this time, the system control means reduces heating output and increases the heating capacity of the gas cooler-condenser 34. If the defrosting need is still not met, the system 10 may initiate step 3, in which the outdoor cooling coil of the gas cooler assembly 32 is turned off and the indoor cooling circuit is engaged while still rejecting heat through the gas cooler-condenser 34. The defrosting sequence may end after a predetermined time or after a "clean" reading from the frost detection system.

[0018] 3 is a schematic diagram of an alternative refrigeration system 110 configured for operation at low ambient temperatures. Refrigeration system 110 also includes medium-temperature primary compressors 112 forming a first suction group for compressing refrigerant to a supercritical state. The primary compressors 112 may have a low suction temperature threshold of approximately 0°F. A liquid accumulator 114 is fluidly connected to each primary compressor 112, or alternatively, to the entire first suction group. An oil separator 116 removes oil and other contaminants from the compressed refrigerant, which may be collected in an oil receiver 120.

[0019] The refrigeration system 110 further includes a first heat recovery circuit 122 and an optional second heat recovery circuit 124, each including a heat exchanger 126, 128. The first and second heat recovery circuits 122, 124 can be bypassed by operation of a bypass valve 130. A gas cooler assembly 132 is downstream of the first and second heat recovery circuits 122, 124 on the discharge line 118. The gas cooler assembly 132 can be configured as a horizontal, vertical, angled, or V-bank gas cooler assembly. The gas cooler assembly 132 includes a bypass valve 131 and a gas cooler-condenser 134 fluidly connected upstream of a pair of expansion valves 138, each upstream of an associated evaporator 136. A fan 142 operates to draw air across the adiabatic precooler 140 and into the gas cooler assembly 132. The evaporators 136 can be configured in series to increase the heat absorption of the refrigeration system 110. The bypass valve 131 is operable to bypass the gas cooler assembly 132 and allow the refrigerant to bypass the liquid receiver 144. The gas cooler assembly 132 further includes a bypass valve 182 downstream of the evaporator 136 to bypass the low temperature suction group, as described in more detail below. A damper 171 may be located within or proximate to the gas cooler assembly 132 to provide supplemental heat to the microclimate region. The system 110 may further be operable to perform a defrost sequence substantially similar to that described above with respect to the system 10.

[0020] The gas cooler-condenser 134 discharges the refrigerant to a liquid receiver 144. Any gaseous refrigerant may be supplied to one or more parallel compressors 148 via a parallel compressor suction line 146. An accumulator 150 may be fluidly connected to the one or more parallel compressors 148. An intermediate heat exchanger 152 may optionally be disposed upstream of the liquid receiver 144 to superheat the suction flash gas and further subcool the liquid refrigerant.

[0021] Line 154 fluidly connects liquid receiver 144 to evaporator 136 of gas cooler assembly 132 via expansion valve 138. Refrigerant is discharged from evaporator 136 along primary compressor suction line 156 and returned to primary compressor 112. At least a portion of the liquefied refrigerant from liquid receiver 144 may be supplied to first refrigeration circuit 158 ​​and second refrigeration circuit 172. First refrigeration circuit 158 ​​includes heat exchanger 162, and second refrigeration circuit 172 includes heat exchanger 176. Expansion valves 160 and 174 reduce the temperature and pressure of the liquefied refrigerant for circulation through heat exchangers 162 and 176, respectively, to absorb heat from and provide cooling to the working fluid of an associated refrigeration system, such as those listed above with respect to refrigeration circuit 58 of system 10. Refrigerant circulated through first refrigeration circuit 158 ​​and / or second refrigeration circuit 172 may be returned along suction line 156 to primary compressor 112.

[0022] Refrigeration system 110 further includes a low-temperature compressor 178 and an associated liquid accumulator 180. The low-temperature compressor 178 forms a second (i.e., low-temperature) suction group. The low-temperature compressor 178 may operate simultaneously with the primary compressor 112 to "pump" refrigerant to a suitable pressure and temperature for the primary compressor 112 under low ambient operating conditions having outside air temperatures ranging from -40°F to -0°F (-40°C to -17.8°C). The low-temperature compressor 178 has a low threshold suction temperature, such as -50°F (-45.5°C) in the exemplary embodiment and -69.7°F (-56.5°C) in an alternative embodiment. A bypass valve 182 allows refrigerant to be supplied to the low-temperature compressor 178 during low ambient operating conditions and allows the low-temperature compressor 178 to be bypassed when low ambient operating conditions are not present. A cold discharge line 184 supplies the "boosted" refrigerant to the suction line 156 and back to the primary compressor 112. A desuperheater exchanger 186 is disposed in thermal communication with the cold discharge line 184 and may desuperheat the refrigerant to a temperature suitable for the primary compressor 112 to recompress.

[0023] The refrigeration systems 10, 110 may be in wired or wireless communication with controllers 61, 161, respectively, to control various system operating modes, microclimate generation, valves, compressors, dampers, fans, etc. The systems 10, 110 may be electrically powered systems configured to receive power from one or more sources, such as fuel, solar, wind, hydroelectric, off-grid energy, etc. In some embodiments, the controllers 61, 161 may be configured to switch between power sources.

[0024] Further alternative embodiments of the disclosed refrigeration system may include two or more heat recovery circuits, two or more refrigeration circuits, one or more gas cooler assemblies, and various other associated hardware, to name a few non-limiting examples.

[0025] The disclosed refrigeration system has many advantages. First, transcritical R-744 CO2 can achieve relatively high temperatures, has the ability to reject heat to various heating systems, and has enough "waste heat" to create a microclimate that prevents frost buildup on the evaporator. The system can operate in superheat and cooling modes simultaneously without backflowing the refrigerant. The gas cooler assembly operates to recover energy from waste heat in a refrigerant-to-air and air-to-refrigerant manner by flowing ambient air over the gas cooler-condenser to raise the air temperature and create a microclimate that raises the refrigerant temperature in the evaporator. Many existing refrigeration systems recover energy from waste heat in a refrigerant-to-refrigerant manner, which can lead to harmful overheating of the refrigerant. Finally, CO2 refrigerant is non-flammable, not an ozone-depleting substance, has a low global warming potential (GWP), and is more environmentally friendly than fluorocarbon-based refrigerants because it does not decompose into "forever chemicals" like PFAS (per- and polyfluoroalkyl substances) refrigerants and other synthetic refrigerants.

[0026] [Consideration of possible embodiments] The following is a non-exclusive description of possible embodiments of the present invention.

[0027] The transcritical refrigeration system includes at least one primary compressor, at least one heat recovery circuit, and at least one gas cooler assembly, wherein the at least one primary compressor is configured to increase the pressure and temperature of a carbon dioxide (CO2) refrigerant to a first refrigerant temperature, the at least one heat recovery circuit is downstream of the at least one primary compressor and configured to absorb at least a first amount of heat from the CO2 refrigerant to reduce the temperature of the CO2 refrigerant to a second refrigerant temperature, and the at least one gas cooler assembly is downstream of the at least one heat recovery circuit. The gas cooler assembly includes at least one gas cooler-condenser, at least one evaporator, and an expansion valve, the at least one gas cooler-condenser including an inlet and an outlet, the inlet configured to receive the CO refrigerant at the second refrigerant temperature, the at least one evaporator including an inlet and an outlet, the inlet fluidly connected downstream of the outlet of the at least one gas cooler-condenser, and the expansion valve disposed upstream of the inlet of the at least one evaporator.

[0028] The gas cooler assembly of the preceding paragraph may optionally, additionally and / or alternatively include any one or more of the following features, configurations, and / or additional components.

[0029] In the above refrigeration system, the at least one gas cooler assembly may further include at least one fan, the at least one fan configured to draw an external airflow into the at least one gas cooler assembly.

[0030] In any of the above refrigeration systems, the at least one gas cooler assembly may further include a bypass valve, the bypass valve being positioned upstream of the inlet of the at least one gas cooler-condenser.

[0031] In any of the above refrigeration systems, the evaporator may be configured to receive the CO2 refrigerant at a third refrigerant temperature and to discharge the CO2 refrigerant at a fourth refrigerant temperature.

[0032] Any of the above refrigeration systems may further include a liquid receiver located downstream of the gas cooler-condenser and configured to receive the CO2 refrigerant.

[0033] Any of the above refrigeration systems may further include at least one parallel compressor downstream of the liquid receiver and configured to compress flash gas.

[0034] Any of the above refrigeration systems may further include a refrigeration circuit downstream of the liquid receiver and configured to reject heat to the CO2 refrigerant.

[0035] In any of the above refrigeration systems, the cooling circuit may include one of a chiller, a cooler, a freezer, a chilled water system, and a refrigeration system.

[0036] In any of the above refrigeration systems, the at least one primary compressor may include two medium temperature compressors.

[0037] In any of the above refrigeration systems, the first refrigerant temperature may be in the range of 90°F to 325°F and the second refrigerant temperature may be in the range of 88°F to 300°F.

[0038] In any of the above refrigeration systems, the at least one heat recovery circuit may include one of a steam boiler, an electric boiler, a hot water boiler, a water heater, an underfloor heating system, a district heating system, a thermal mass storage system, and a phase change material (PCM) storage system.

[0039] In any of the above refrigeration systems, the at least one heat recovery circuit may include a first heat recovery circuit and a second heat recovery circuit.

[0040] In any of the above refrigeration systems, the first heat recovery circuit may include a first heat exchanger, and the second heat recovery circuit may include a second heat exchanger, and the first heat exchanger and the second heat exchanger may be connected in series to the at least one gas cooler-condenser.

[0041] Any of the above refrigeration systems may include at least one low-temperature compressor and a bypass valve for selectively bypassing the at least one low-temperature compressor and downstream of the at least one evaporator.

[0042] Any of the above refrigeration systems may further include a control unit.

[0043] A method of operating a transcritical refrigeration system includes using at least one primary compressor to increase the pressure and temperature of a carbon dioxide (CO2) refrigerant to a first refrigerant temperature; circulating the CO2 refrigerant at the first refrigerant temperature through at least one heat recovery circuit and rejecting heat to the at least one heat recovery circuit to reduce the temperature of the CO2 refrigerant to a second refrigerant temperature; circulating the CO2 refrigerant at the second refrigerant temperature through at least one gas cooler-condenser of a gas cooler assembly; drawing an external air stream at a first air temperature across the at least one gas cooler-condenser to reduce the temperature of the CO2 refrigerant to a third refrigerant temperature and increase the air temperature of the external air stream to a second air temperature.

[0044] The method of the preceding paragraph may optionally additionally and / or alternatively include any one or more of the following features, configurations, and / or additional components.

[0045] In any of the above methods, increasing the air temperature generates a microclimate downstream of at least one gas cooler-condenser and upstream of at least one evaporator of the gas cooler assembly relative to the direction of the external airflow.

[0046] Any of the above methods may further include using the microclimate to prevent frost buildup on the evaporator.

[0047] Any of the above methods may further include circulating at least a portion of the CO refrigerant through the refrigeration circuit downstream of the gas cooler-condenser and the at least one heat recovery circuit such that the refrigeration circuit downstream of the gas cooler-condenser and the at least one heat recovery circuit are simultaneously energized.

[0048] In any of the above methods, circulating the CO2 refrigerant through at least one heat recovery circuit at the first refrigerant temperature may include circulating the CO2 refrigerant continuously through a first heat recovery circuit and a second heat recovery circuit.

[0049] While the present invention has been described with reference to exemplary embodiments, it will be apparent to those skilled in the art that various modifications may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed, but rather to include all embodiments falling within the scope of the appended claims.

Claims

1. 1. A transcritical refrigeration system comprising: at least one primary compressor, at least one heat recovery circuit, and at least one gas cooler assembly; The at least one primary compressor is configured to generate carbon dioxide (CO ２ ) increasing the pressure and temperature of the refrigerant to a first refrigerant temperature; The at least one heat recovery circuit is downstream of the at least one primary compressor, and the CO ２ Absorbing at least a first amount of heat from the refrigerant to produce the CO ２ configured to reduce the temperature of the refrigerant to a second refrigerant temperature; the at least one gas cooler assembly is downstream of the at least one heat recovery circuit and comprises at least one gas cooler-condenser, at least one evaporator, and an expansion valve; The at least one gas cooler-condenser includes an inlet and an outlet, the inlet being configured to condense the CO 2 at the second refrigerant temperature. ２ configured to receive a refrigerant; the at least one evaporator having an inlet and an outlet, the inlet being fluidly connected downstream of the outlet of the at least one gas cooler-condenser; The expansion valve is disposed upstream of the inlet of the at least one evaporator.

2. 2. The refrigeration system of claim 1, the at least one gas cooler assembly further comprising at least one fan; The at least one fan is configured to draw an external airflow through the at least one gas cooler assembly.

3. 2. The refrigeration system of claim 1, the at least one gas cooler assembly further comprising a bypass valve; The refrigeration system, wherein the bypass valve is located upstream of the inlet of the at least one gas cooler-condenser.

4. 2. The refrigeration system of claim 1, The evaporator generates the CO at a third refrigerant temperature. ２ receiving a refrigerant and dissolving the CO ２ The refrigeration system is configured to discharge a refrigerant.

5. 2. The refrigeration system of claim 1, further comprising a liquid receiver; The liquid receiver is provided downstream of the gas cooler-condenser, and the CO ２ A refrigeration system configured to receive a refrigerant.

6. 6. The refrigeration system of claim 5, further comprising at least one parallel compressor; The at least one parallel compressor is downstream of the liquid receiver and configured to compress flash gas.

7. 6. The refrigeration system of claim 5, Further comprising a cooling circuit; The cooling circuit is downstream of the liquid receiver, and the CO ２ The refrigeration system is configured to reject heat to a refrigerant.

8. 8. The refrigeration system of claim 7, The refrigeration system, wherein the refrigeration circuit includes one of a chiller, a cooler, a freezer, a chilled water system, and a refrigeration system.

9. 2. The refrigeration system of claim 1, The at least one primary compressor includes two medium temperature compressors.

10. 2. The refrigeration system of claim 1, A refrigeration system wherein the first refrigerant temperature is in the range of 90°F to 325°F and the second refrigerant temperature is in the range of 88°F to 300°F.

11. 2. The refrigeration system of claim 1, 1. A refrigeration system, wherein the at least one heat recovery circuit comprises one of a steam boiler, an electric boiler, a hot water boiler, a water heater, an underfloor heating system, a district heating system, a thermal mass storage system, and a phase change material (PCM) storage system.

12. 2. The refrigeration system of claim 1, The at least one heat recovery circuit comprises a first heat recovery circuit and a second heat recovery circuit.

13. 13. The refrigeration system of claim 12, the first heat recovery circuit comprises a first heat exchanger; the second heat recovery circuit comprises a second heat exchanger; The refrigeration system, wherein the first heat exchanger and the second heat exchanger are connected in series with the at least one gas cooler-condenser.

14. 2. The refrigeration system of claim 1, at least one low temperature compressor and a bypass valve; The bypass valve is for selectively bypassing the at least one low temperature compressor and is downstream of the at least one evaporator.

15. 2. The refrigeration system of claim 1, The refrigeration system further comprises a control unit.

16. 1. A method of operating a transcritical refrigeration system, comprising: At least one primary compressor is used to generate carbon dioxide (CO ２ ) increasing the pressure and temperature of the refrigerant to a first refrigerant temperature; CO at the first refrigerant temperature ２ circulating a refrigerant through at least one heat recovery circuit and rejecting heat to said at least one heat recovery circuit; ２ reducing the temperature of the refrigerant to a second refrigerant temperature; and refrigerating the CO at the second refrigerant temperature through at least one gas cooler-condenser of a gas cooler assembly. ２ circulating a refrigerant; drawing an external air stream at a first air temperature across said at least one gas cooler-condenser; ２ reducing the temperature of the refrigerant to a third refrigerant temperature and increasing the air temperature of the external air stream to a second air temperature.

17. 17. The method of claim 16, The method, wherein increasing the air temperature generates a microclimate downstream of at least one gas cooler-condenser and upstream of at least one evaporator of the gas cooler assembly relative to the direction of the external airflow.

18. 18. The method of claim 17, The method further comprising using the microclimate to prevent frost buildup on the evaporator.

19. 17. The method of claim 16, The CO 2 is supplied through the cooling circuit so that the cooling circuit downstream of the gas cooler-condenser and the at least one heat recovery circuit are simultaneously energized. ２ The method further comprising circulating at least a portion of the refrigerant.

20. 17. The method of claim 16, The CO ２ Circulating the refrigerant through at least one heat recovery circuit at the first refrigerant temperature ２ A method comprising continuously circulating a refrigerant through a first heat recovery circuit and a second heat recovery circuit.

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