Integrated Air-Conditioning Circuit and CO2 Refrigeration System Incorporating Same

Abstract

The present invention relates to an integrated air-conditioning (A/C) circuit for a Carbon Dioxide (CO2) refrigeration system having a CO2 based refrigerant circuit including a high pressure refrigerant cooling heat exchanger that passes refrigerant received at a high pressure in heat exchange relationship with a cooling medium. The A/C circuit is nested within the CO2 refrigeration system and includes a means of directing discharge from an outlet line of the refrigerant cooling heat exchanger into the nested air-conditioning circuit. The A/C circuit further includes a means of reducing the pressure of the refrigerant directed from the outlet line of the refrigerant cooling heat exchanger, and a refrigerant heating heat exchanger for receiving the refrigerant having a reduced pressure and passing the refrigerant in heat exchange relationship with a heating medium to generate chilled fluid.

1 . An integrated air-conditioning (A/C) circuit for a Carbon Dioxide (CO 2 ) refrigeration system having a CO 2  based refrigerant circuit including a high pressure refrigerant cooling heat exchanger that passes refrigerant received at a high pressure in heat exchange relationship with a cooling medium, wherein the A/C circuit is nested within the CO 2  refrigeration system and includes:
 a means of directing discharge from an outlet line of the refrigerant cooling heat exchanger into the nested air-conditioning circuit,   a means of reducing the pressure of the refrigerant directed from the outlet line of the refrigerant cooling heat exchanger, and   a refrigerant heating heat exchanger for receiving the refrigerant having a reduced pressure and passing the refrigerant in heat exchange relationship with a heating medium to generate chilled fluid.   
     
     
         2 . An integrated air-conditioning circuit according to  claim 1 , further including:
 a means of re-compressing the refrigerant from the refrigerant heating heat exchanger before passing the refrigerant to an inlet line of the refrigerant cooling heat exchanger.   
     
     
         3 . An integrated air-conditioning circuit according to  claim 1 , wherein the chilled fluid is chilled water generated when the refrigerant heating heat exchanger is a CO 2 :H 2 O heat exchanger. 
     
     
         4 . An integrated air-conditioning circuit according to  claim 1 , wherein the chilled fluid chilled air generated when the refrigerant heating heat exchanger is a CO 2  ambient air heat exchanger. 
     
     
         5 . An integrated air-conditioning circuit according to  claim 1 , wherein the means of reducing the pressure of the refrigerant is an expansion valve located upstream of the refrigerant heating heat exchanger which expands the refrigerant directly into the refrigerant heating heat exchanger. 
     
     
         6 . An integrated air-conditioning circuit according to  claim 1 , wherein the means of re-compressing the refrigerant from the refrigerant heating heat exchanger before passing the refrigerant back to the inlet line of the refrigerant cooling heat exchanger is one or more refrigerant compression devices. 
     
     
         7 . An integrated air-conditioning circuit according to  claim 6 , wherein the one or more refrigerant compression devices are one or more dedicated A/C compressors located downstream of the refrigerant heating heat exchanger operating at approximately 5 to 7 degrees Celsius. 
     
     
         8 . An integrated air-conditioning circuit according to  claim 1 , further including:
 a means of pumping the generated chilled fluid to an A/C chilled fluid handling evaporator for the purpose of utilising the chilled fluid for air-conditioning.   
     
     
         9 . An integrated air-conditioning circuit according to  claim 1 , wherein in addition to including a high-pressure refrigerant cooling heat exchanger, the CO 2  based refrigerant circuit further includes:
 one or more refrigerant compression devices located upstream of the refrigerant cooling heat exchanger,   a refrigerant heating heat exchanger for passing refrigerant at a low pressure in heat exchange relationship with a heating medium, and   an expansion device disposed in the CO 2  based refrigerant circuit downstream of said refrigerant cooling heat exchanger and upstream of said refrigerant heating heat exchanger.   
     
     
         10 . An integrated air-conditioning circuit according to  claim 9 , wherein the refrigeration system further includes:
 a flash tank receiver disposed in the CO 2  based refrigerant circuit downstream of said refrigerant cooling heat exchanger and upstream of said expansion device,   at least one ejector disposed in the CO 2  based refrigerant circuit downstream of said refrigerant cooling heat exchanger and upstream of said flash tank receiver,   a three-way valve disposed at an entry side of the one or more refrigerant compression devices, and   a controller operable to switch the mode of operation of the refrigeration system, from:
 a baseline mode in which the flash tank receiver receives refrigerant exclusively from the refrigerant cooling heat exchanger, and vapour refrigerant from the flash tank receiver is caused to pass through a first refrigerant line from the flash tank receiver to the refrigerant compression device such that refrigerant passing from the refrigerant heating heat exchanger of the refrigerant circuit to the refrigerant compression device is mixed with said vapour refrigerant from the flash tank, the flash gas receiver having associated therewith a flash gas bypass valve to manage flash gas as it accumulates in the flash gas receiver, to: 
 a parallel compression mode in which the flash gas bypass valve is closed and vapour refrigerant from the flash tank receiver is caused to pass through a second refrigerant line to one or more second refrigerant compression devices that operate in parallel with the one or more refrigerant compression devices, the one or more second refrigerant compression devices managing the flash gas as it accumulates in the flash gas receiver by recompressing and discharging same to the inlet line of the refrigerant cooling heat exchanger, and subsequently to: 
 an ejector mode in which the three-way valve disposed at an entry side of the one or more refrigerant compression devices is operated to cause vapour refrigerant from the flash tank receiver to, in addition to passing through the second refrigerant line to the one or more second refrigerant compression devices, pass through a third refrigerant line from the flash tank receiver to the one or more refrigerant compression devices, wherein refrigerant from the refrigerant heating heat exchanger of the refrigerant circuit is diverted through a fourth refrigerant line to the at least one ejector where the refrigerant is mixed with refrigerant from the refrigerant cooling heat exchanger, the flash tank receiver thereby receiving a mix of refrigerants from the refrigerant heating heat exchanger and the refrigerant cooling heat exchanger. 
   
     
     
         11 . An integrated air-conditioning circuit according to  claim 9 , wherein the refrigeration system further includes:
 a flash tank receiver disposed in the CO 2  based refrigerant circuit downstream of said refrigerant cooling heat exchanger and upstream of said expansion device,   at least one ejector disposed in the CO 2  based refrigerant circuit downstream of said refrigerant cooling heat exchanger and upstream of said flash tank receiver,   a three-way valve disposed at an entry side of the one or more refrigerant compression devices and operable to switch the mode of operation of the refrigeration system between:   a first mode in which the flash tank receiver receives refrigerant exclusively from the refrigerant cooling heat exchanger such that vapour refrigerant from the flash tank receiver is caused to pass through a first refrigerant line from the flash tank receiver to the one or more refrigerant compression devices with refrigerant passing from the refrigerant heating heat exchanger of the refrigerant circuit to the one or more refrigerant compression devices mixed with said vapour refrigerant from the flash tank, and   a second mode in which the vapour refrigerant from the flash tank receiver is caused to pass through a second refrigerant line from the flash tank receiver to the one or more refrigerant compression devices such that the one or more refrigerant compression devices are supplied refrigerant exclusively from the flash gas receiver, wherein refrigerant from the refrigerant heating heat exchanger of the refrigerant circuit is diverted through a third refrigerant line to the at least one ejector with the refrigerant mixed with refrigerant from the refrigerant cooling heat exchanger, the flash tank receiver thereby receiving a mixture of refrigerants from the refrigerant heating heat exchanger and the refrigerant cooling heat exchanger, and   a controller operatively associated with the three-way valve, the controller operable to cause the refrigeration system to transition directly from the first to the second mode of operation when a particular condition has been detected.   
     
     
         12 . An integrated air-conditioning circuit according to  claim 9 , wherein the refrigeration system further includes:
 a flash tank receiver disposed in the CO 2  based refrigerant circuit downstream from said refrigerant cooling heat exchanger, the flash tank receiver having associated therewith a flash gas bypass valve,   at least one liquid ejector disposed in the CO 2  based refrigerant circuit downstream of said refrigerant cooling heat exchanger and upstream of said flash tank receiver, and   a suction accumulator disposed in the refrigerant circuit downstream of the refrigerant heating heat exchanger of the refrigerant circuit to capture any liquid refrigerant from the refrigerant heating heat exchanger of the refrigerant circuit, wherein the mode of operation of the refrigeration system is configured to be switched between:   a first mode of operation in which the flash tank receiver receives refrigerant exclusively from the refrigerant cooling heat exchanger such that vapour refrigerant from the flash tank receiver is caused to pass through a refrigerant line from the flash tank receiver to the one or more refrigerant compression devices with refrigerant passing from the refrigerant heating heat exchanger of the refrigerant circuit to the one or more refrigerant compression devices mixed with said vapour refrigerant from the flash tank, and   a second mode of operation wherein the at least one liquid ejector is operated to entrain a portion of liquid refrigerant recovered from the suction accumulator and to re-inject said liquid back into the flash tank receiver, where the flash gas bypass valve is configured to manage flash gas build-up in the receiver, and   a controller operatively associated with the three-way valve, the controller operable to cause the refrigeration system to transition directly from the first to the second mode of operation when a particular condition has been detected.   
     
     
         13 . An integrated air-conditioning circuit according to  claim 11 , wherein the controller is configured to automatically activate or schedule the transition from the first to the second mode of operation upon determining the particular condition which includes one or more of:
 dry-bulb ambient temperature increasing from a first temperature below approximately 25 degrees Celsius to a second temperature equal to or greater than approximately 25 degrees Celsius, and   a temperature at a discharge of the refrigerant cooling heat exchanger increasing from a first temperature below approximately 27 degrees Celsius to a second temperature equal to or greater than approximately 27 degrees Celsius.   
     
     
         14 . An integrated air-conditioning circuit according to  claim 10 , wherein the refrigeration system further includes a second refrigerant heating heat exchanger arranged in parallel with the refrigerant heating heat exchanger with an associated expansion device, and associated with a second expansion device, the second refrigerant heating heat exchanger also configured to pass refrigerant at a low pressure in heat exchange relationship with a heating medium, the refrigerant heating heat exchanger configured to output MT refrigerant, and the second refrigerant heating heat exchanger configured to output low temperature (LT) refrigerant. 
     
     
         15 . An integrated air-conditioning circuit according to  claim 10 , wherein the integrated air-conditioning circuit is operated when an associated store requires temperature and/or humidity adjustment, including at any time during said different modes of operation. 
     
     
         16 . A Carbon Dioxide (CO 2 ) refrigeration system including an integrated air-conditioning circuit according to  claim 1 . 
     
     
         17 . A Carbon Dioxide (CO 2 ) refrigeration system including:
 a CO 2  based refrigerant circuit including:
 a high-pressure refrigerant cooling heat exchanger that passes refrigerant received at a high pressure in heat exchange relationship with a cooling medium, 
   one or more refrigerant compression devices located upstream of the refrigerant cooling heat exchanger,   a refrigerant heating heat exchanger for passing refrigerant at a low pressure in heat exchange relationship with a heating medium, and   an expansion device disposed downstream of said refrigerant cooling heat exchanger and upstream of said refrigerant heating heat exchanger,   a flash tank receiver disposed in the CO 2  based refrigerant circuit downstream of said refrigerant cooling heat exchanger and upstream of said expansion device,   at least one ejector disposed in the CO 2  based refrigerant circuit downstream of said refrigerant cooling heat exchanger and upstream of said flash tank receiver,   a three-way valve disposed at an entry side of the one or more refrigerant compression devices, and   a controller operable to switch the mode of operation of the refrigeration system, from:   a baseline mode in which the flash tank receiver receives refrigerant exclusively from the refrigerant cooling heat exchanger, and vapour refrigerant from the flash tank receiver is caused to pass through a first refrigerant line from the flash tank receiver to the refrigerant compression device such that refrigerant passing from the refrigerant heating heat exchanger of the refrigerant circuit to the refrigerant compression device is mixed with said vapour refrigerant from the flash tank, the flash gas receiver having associated therewith a flash gas bypass valve to manage flash gas as it accumulates in the flash gas receiver, to:   a parallel compression mode in which the flash gas bypass valve is closed and vapour refrigerant from the flash tank receiver is caused to pass through a second refrigerant line to one or more second refrigerant compression devices that operate in parallel with the one or more refrigerant compression devices, the one or more second refrigerant compression devices managing the flash gas as it accumulates in the flash gas receiver by recompressing and discharging same to the inlet line of the refrigerant cooling heat exchanger, and subsequently to:   an ejector mode in which the three-way valve disposed at an entry side of the one or more refrigerant compression devices is operated to cause vapour refrigerant from the flash tank receiver to, in addition to passing through the second refrigerant line to the one or more second refrigerant compression devices, pass through a third refrigerant line from the flash tank receiver to the one or more refrigerant compression devices, wherein refrigerant from the refrigerant heating heat exchanger of the refrigerant circuit is diverted through a fourth refrigerant line to the at least one ejector where the refrigerant is mixed with refrigerant from the refrigerant cooling heat exchanger, the flash tank receiver thereby receiving a mix of refrigerants from the refrigerant heating heat exchanger and the refrigerant cooling heat exchanger, and   an integrated A/C circuit, including:
 a means of directing discharge from an outlet line of the refrigerant cooling heat exchanger into the integrated air-conditioning circuit, 
 a means of reducing the pressure of the refrigerant directed from the outlet line of the refrigerant cooling heat exchanger, 
 a second refrigerant heating heat exchanger for receiving the refrigerant of reduced pressure and passing the refrigerant in heat exchange relationship with a heating medium to generate chilled fluid, and 
 a means of re-compressing the refrigerant from the second refrigerant heating heat exchanger before passing the refrigerant to an inlet line of the refrigerant cooling heat exchanger. 
   
     
     
         18 . A Carbon Dioxide (CO 2 ) refrigeration system including:
 a CO 2  based refrigerant circuit including:
 a high-pressure refrigerant cooling heat exchanger that passes refrigerant received at a high pressure in heat exchange relationship with a cooling medium, 
 one or more refrigerant compression devices located upstream of the refrigerant cooling heat exchanger, 
 a refrigerant heating heat exchanger for passing refrigerant at a low pressure in heat exchange relationship with a heating medium, and 
 an expansion device disposed downstream of said refrigerant cooling heat exchanger and upstream of said refrigerant heating heat exchanger, 
   a flash tank receiver disposed in the CO 2  based refrigerant circuit downstream of said refrigerant cooling heat exchanger and upstream of said expansion device,   at least one ejector disposed in the CO 2  based refrigerant circuit downstream of said refrigerant cooling heat exchanger and upstream of said flash tank receiver,   a three-way valve disposed at an entry side of the one or more refrigerant compression devices and operable to switch the mode of operation of the refrigeration system between:
 a first mode in which the flash tank receiver receives refrigerant exclusively from the refrigerant cooling heat exchanger such that vapour refrigerant from the flash tank receiver is caused to pass through a first refrigerant line from the flash tank receiver to the one or more refrigerant compression devices with refrigerant passing from the refrigerant heating heat exchanger of the refrigerant circuit to the one or more refrigerant compression devices mixed with said vapour refrigerant from the flash tank, and 
 a second mode in which the vapour refrigerant from the flash tank receiver is caused to pass through a second refrigerant line from the flash tank receiver to the one or more refrigerant compression devices such that the one or more refrigerant compression devices are supplied refrigerant exclusively from the flash gas receiver, wherein refrigerant from the refrigerant heating heat exchanger of the refrigerant circuit is diverted through a third refrigerant line to the at least one ejector with the refrigerant mixed with refrigerant from the refrigerant cooling heat exchanger, the flash tank receiver thereby receiving a mixture of refrigerants from the refrigerant heating heat exchanger and the refrigerant cooling heat exchanger, and 
   a controller operatively associated with the three-way valve, the controller operable to cause the refrigeration system to transition directly from the first to the second mode of operation when a particular condition has been detected, and   an integrated A/C circuit, including:
 a means of directing discharge from an outlet line of the refrigerant cooling heat exchanger into the integrated air-conditioning circuit, 
 a means of reducing the pressure of the refrigerant directed from the outlet line of the refrigerant cooling heat exchanger, 
 a second refrigerant heating heat exchanger for receiving the refrigerant of reduced pressure and passing the refrigerant in heat exchange relationship with a heating medium to generate chilled fluid, and 
 a means of re-compressing the refrigerant from the second refrigerant heating heat exchanger before passing the refrigerant to an inlet line of the refrigerant cooling heat exchanger. 
   
     
     
         19 . A Carbon Dioxide (CO 2 ) refrigeration system including:
 a CO 2  based refrigerant circuit including:
 a high-pressure refrigerant cooling heat exchanger that passes refrigerant received at a high pressure in heat exchange relationship with a cooling medium, 
 one or more refrigerant compression devices located upstream of the refrigerant cooling heat exchanger, 
 a refrigerant heating heat exchanger for passing refrigerant at a low pressure in heat exchange relationship with a heating medium, and 
 an expansion device disposed downstream of said refrigerant cooling heat exchanger and upstream of said refrigerant heating heat exchanger, 
   a flash tank receiver disposed in the CO 2  based refrigerant circuit downstream of said refrigerant cooling heat exchanger, the flash tank receiver having associated therewith a flash gas bypass valve,   at least one liquid ejector disposed in the CO 2  based refrigerant circuit downstream of said refrigerant cooling heat exchanger and upstream of said flash tank receiver, and   a suction accumulator disposed in the refrigerant circuit downstream of the refrigerant heating heat exchanger of the refrigerant circuit to capture any liquid refrigerant from the refrigerant heating heat exchanger of the refrigerant circuit, wherein the mode of operation of the refrigeration system is configured to be switched between:
 a first mode of operation in which the flash tank receiver receives refrigerant exclusively from the refrigerant cooling heat exchanger such that vapour refrigerant from the flash tank receiver is caused to pass through a refrigerant line from the flash tank receiver to the one or more refrigerant compression devices with refrigerant passing from the refrigerant heating heat exchanger of the refrigerant circuit to the one or more refrigerant compression devices mixed with said vapour refrigerant from the flash tank, and 
 a second mode of operation wherein the at least one liquid ejector is operated to entrain a portion of liquid refrigerant recovered from the suction accumulator and to re-inject said liquid back into the flash tank receiver, where the flash gas bypass valve is configured to manage flash gas build-up in the receiver, with 
   a controller operable to cause the refrigeration system to transition directly from the first to the second mode of operation when a particular condition has been detected, and   an integrated A/C circuit, including:
 a means of directing discharge from an outlet line of the refrigerant cooling heat exchanger into the integrated air-conditioning circuit, 
 a means of reducing the pressure of the refrigerant directed from the outlet line of the refrigerant cooling heat exchanger, 
 a second refrigerant heating heat exchanger for receiving the refrigerant of reduced pressure and passing the refrigerant in heat exchange relationship with a heating medium to generate chilled fluid, and 
 a means of re-compressing the refrigerant from the second refrigerant heating heat exchanger before passing the refrigerant to an inlet line of the refrigerant cooling heat exchanger. 
   
     
     
         20 . An integrated air-conditioning circuit according to  claim 12 , wherein the controller is configured to automatically activate or schedule the transition from the first to the second mode of operation upon determining the particular condition which includes one or more of:
 dry-bulb ambient temperature increasing from a first temperature below approximately 25 degrees Celsius to a second temperature equal to or greater than approximately 25 degrees Celsius, and   a temperature at a discharge of the refrigerant cooling heat exchanger increasing from a first temperature below approximately 27 degrees Celsius to a second temperature equal to or greater than approximately 27 degrees Celsius.