Co2 refrigeration system with after-cooling

Abstract

A refrigeration system includes a refrigeration circuit and a coolant circuit separate from the refrigeration circuit. The refrigerant circuit includes a gas cooler/condenser, a receiver, and an evaporator. The coolant circuit includes a heat exchanger configured to transfer heat from a refrigerant circulating within the refrigeration circuit into a coolant circulating within the coolant circuit, a heat sink configured to remove heat from the coolant circulating within the coolant circuit, and a magnetocaloric conditioning unit configured to transfer heat from the coolant within a first fluid conduit of the coolant circuit into the coolant within a second fluid conduit of the coolant circuit. The first fluid conduit connects an outlet of the heat exchanger to an inlet of the heat sink, whereas the second fluid conduit connects an outlet of the heat sink to an inlet of the heat exchanger.

1 - 20 . (Canceled) 
     
     
         21 . A method of operating a refrigeration system, comprising:
 removing heat from a refrigerant circulating within a refrigeration circuit using a gas cooler/condenser and discharging the refrigerant through an outlet of the gas cooler/condenser;   collecting the refrigerant from the gas cooler/condenser in a receiver having an inlet fluidly coupled to the outlet of the gas cooler/condenser, and discharging the refrigerant through an outlet of the receiver;   receiving the refrigerant from the receiver in an evaporator having an inlet fluidly coupled to the outlet of the receiver, and transferring heat into the refrigerant circulating within the refrigeration circuit using the evaporator;   transferring heat from the refrigerant circulating within the refrigeration circuit into a coolant circulating within a coolant circuit using a heat exchanger, the coolant entering the heat exchanger through a coolant inlet and exiting the heat exchanger through a coolant outlet;   removing heat from the coolant circulating within the coolant circuit using a heat sink, the coolant entering the heat sink through an inlet fluidly coupled to the coolant outlet of the heat exchanger and exiting the heat sink through an outlet fluidly coupled to the coolant inlet of the heat exchanger; and   transferring heat from the coolant within a first fluid conduit of the coolant circuit into the coolant within a second fluid conduit of the coolant circuit using a conditioning unit, the first fluid conduit fluidly coupling the coolant outlet of the heat exchanger to the inlet of the heat sink, and the second fluid conduit fluidly coupling the outlet of the heat sink to the coolant inlet of the heat exchanger.   
     
     
         22 . The method of  claim 21 , wherein transferring heat from the coolant within the first fluid conduit into the coolant within the second fluid conduit comprises performing a refrigeration cycle using the conditioning unit. 
     
     
         23 . The method of  claim 21 , wherein transferring heat from the refrigerant into the coolant comprises positioning the heat exchanger along a fluid conduit of the refrigeration circuit connecting the outlet of the gas cooler/condenser to the inlet of the receiver. 
     
     
         24 . The method of  claim 23 , wherein the refrigeration circuit comprises a high pressure valve positioned along the fluid conduit connecting the outlet of the gas cooler/condenser to the inlet of the receiver, and the method comprises:
 operating the heat exchanger between the gas cooler/condenser and the high pressure valve to provide additional cooling for the refrigerant exiting the gas cooler/condenser before the refrigerant reaches the high pressure valve.   
     
     
         25 . The method of  claim 23 , wherein the refrigeration circuit comprises a high pressure valve positioned along the fluid conduit connecting the outlet of the gas cooler/condenser to the inlet of the receiver, and the method comprises:
 operating the heat exchanger between the high pressure valve and the receiver to provide cooling for the refrigerant traveling from the high pressure valve to the receiver.   
     
     
         26 . The method of  claim 21 , wherein transferring heat from the refrigerant into the coolant comprises operating the heat exchanger along a fluid conduit of the refrigeration circuit that connects the outlet of the receiver to the inlet of the evaporator to subcool the refrigerant exiting the receiver before the refrigerant reaches the evaporator. 
     
     
         27 . The method of  claim 21 , wherein the coolant circuit comprises:
 a bypass conduit fluidly coupling the second fluid conduit of the coolant circuit to the first fluid conduit of the coolant circuit in parallel with the heat exchanger, the bypass conduit comprising an alternative flow path for the coolant to travel from the second fluid conduit to the first fluid conduit without passing through the heat exchanger; and   a control valve positioned along the bypass conduit, and the method comprises:   controlling a flow of the coolant through at least one of the bypass conduit and the heat exchanger using the control valve.   
     
     
         28 . The method of  claim 27 , comprising:
 measuring a temperature of the coolant using a temperature sensor positioned along the first fluid conduit between the conditioning unit and a location at which the bypass conduit and the first fluid conduit intersect; and   operating the control valve to maintain the temperature of the coolant measured by the temperature sensor at or below a temperature setpoint by varying an amount of the coolant permitted to bypass the heat exchanger via the bypass conduit.   
     
     
         29 . The method of  claim 21 , wherein the refrigeration circuit comprises one or more compressors, and the method comprises:
 compressing the refrigerant using the one or more compressors and discharging the compressed refrigerant into a compressor discharge line; and   positioning the heat exchanger along the compressor discharge line and removing heat from the compressed refrigerant in the compressor discharge line using the heat exchanger.   
     
     
         30 . The method of  claim 29 , comprising:
 controlling a flow of the coolant through the heat exchanger using a control valve; and   operating the control valve to maintain a superheat of the refrigerant exiting the heat exchanger at a predetermined superheat setpoint by varying an amount of heat removed from the compressed refrigerant in the heat exchanger.   
     
     
         31 . The method of  claim 29 , comprising:
 controlling a flow of the coolant through the heat exchanger using a control valve; and   operating the control valve to cause the compressed refrigerant in the heat exchanger to fully condense to a liquid refrigerant by controlling an amount of heat removed from the compressed refrigerant in the heat exchanger.   
     
     
         32 . The method of  claim 31 , wherein the heat exchanger comprises a refrigerant outlet fluidly coupled to the receiver, and the method comprises:
 delivering the liquid refrigerant from the heat exchanger to the receiver through the refrigerant outlet.   
     
     
         33 . The method of  claim 21 , wherein the coolant circuit comprises a plurality of heat exchangers, and the method comprises:
 transferring heat from the refrigerant circulating within the refrigeration circuit into the coolant circulating within the coolant circuit using the plurality of heat exchangers, the transferring comprising:
 providing additional cooling for the refrigerant traveling from the gas cooler/condenser to the receiver using a first heat exchanger positioned along a fluid conduit of the refrigeration circuit connecting the outlet of the gas cooler/condenser to the inlet of the receiver; and 
 removing heat from the refrigerant in a compressor discharge line using a second heat exchanger positioned along the compressor discharge line of the refrigeration circuit. 
   
     
     
         34 . The method of  claim 21 , wherein the refrigeration circuit comprises one or more compressors, and the method comprises:
 receiving the refrigerant from a compressor suction line using the one or more compressors, compressing the refrigerant, and discharging the compressed refrigerant into a compressor discharge line; and   positioning the heat exchanger along the compressor suction line and removing heat from the compressed refrigerant in the compressor suction line using the heat exchanger.   
     
     
         35 . The method of  claim 34 , wherein removing heat from the refrigerant in the heat exchanger causes the refrigerant to at least partially condense into a liquid or a mixture of liquid and gas, and the method comprises:
 separating a liquid portion of the refrigerant exiting the heat exchanger from a gas portion of the refrigerant exiting the heat exchanger using a liquid/vapor separator fluidly coupled to a refrigerant outlet of the heat exchanger.   
     
     
         36 . The method of  claim 35 , wherein the liquid/vapor separator comprises:
 a liquid refrigerant outlet fluidly coupled to the inlet of the receiver; and   a gas refrigerant outlet fluidly coupled to the compressor suction line, and the method comprises:   delivering the liquid portion of the refrigerant to the receiver through the liquid refrigerant outlet and delivering the gas portion of the refrigerant to the compressor suction line through the gas refrigerant outlet.   
     
     
         37 . A method of operating a refrigeration system, comprising:
 transferring heat from a refrigerant circulating within a refrigeration circuit into a coolant circulating within a coolant circuit using a heat exchanger, the coolant entering the heat exchanger through a coolant inlet and exiting the heat exchanger through a coolant outlet;   removing heat from the coolant circulating within the coolant circuit using a heat sink, the coolant entering the heat sink through an inlet fluidly coupled to the coolant outlet of the heat exchanger and exiting the heat sink through an outlet fluidly coupled to the coolant inlet of the heat exchanger; and   transferring heat from the coolant within a first fluid conduit of the coolant circuit into the coolant within a second fluid conduit of the coolant circuit using a conditioning unit, the first fluid conduit fluidly coupling the coolant outlet of the heat exchanger to the inlet of the heat sink, and the second fluid conduit fluidly coupling the outlet of the heat sink to the coolant inlet of the heat exchanger.   
     
     
         38 . The method of  claim 37 , wherein transferring heat from the coolant within the first fluid conduit into the coolant within the second fluid conduit comprises performing a refrigeration cycle using the conditioning unit. 
     
     
         39 . The method of  claim 37 , comprising:
 controlling a flow of the coolant through the heat exchanger using a control valve; and   operating the control valve to maintain a superheat of the refrigerant exiting the heat exchanger at a predetermined superheat setpoint by varying an amount of heat removed from the refrigerant in the heat exchanger.   
     
     
         40 . The method of  claim 37 , comprising:
 controlling a flow of the coolant through the heat exchanger using a control valve; and   operating the control valve to cause the refrigerant in the heat exchanger to condense to a liquid refrigerant by controlling an amount of heat removed from the refrigerant in the heat exchanger.