Integrated Air-Conditioning Circuit and CO2 Refrigeration System Incorporating Same

A Carbon Dioxide (CO2) refrigeration system including:

• 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,
• 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 CO2 based refrigerant circuit downstream of said refrigerant cooling heat exchanger and upstream of said expansion device,
• at least one ejector disposed in the CO2 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.

A Carbon Dioxide (CO2) refrigeration system including:

• 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,
• 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 CO2 based refrigerant circuit downstream of said refrigerant cooling heat exchanger and upstream of said expansion device,
• at least one ejector disposed in the CO2 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.

A Carbon Dioxide (CO2) refrigeration system including:

• 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,
• 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 CO2 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 CO2 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.