Refrigerant vapor compression system with hot gas bypass

Abstract

A refrigerant vapor compression system includes a hot gas bypass line establishing refrigerant vapor flow communication between the compression device and the refrigerant heat absorption heat exchanger, and bypassing the refrigerant heat rejection heat exchanger and the primary expansion device. A refrigerant vapor flow control device is interdisposed in the hot gas bypass line. The flow control device has at least a first open position in which refrigerant vapor flow may pass through the hot gas bypass line and a closed position in which refrigerant vapor flow may not pass through the hot gas bypass line.

1 . A refrigerant vapor compression system comprising:
 a primary refrigerant circuit including a refrigerant compression device, a refrigerant heat rejection heat exchanger downstream of said compression device, a refrigerant heat absorption heat exchanger downstream of said refrigerant heat rejection heat exchanger, and a primary expansion device disposed in the refrigerant circuit downstream of said refrigerant heat rejection heat exchanger and upstream of said refrigerant heat absorption heat exchanger;   a hot gas bypass line establishing refrigerant vapor flow communication between a location upstream with respect to refrigerant vapor flow of said refrigerant heat rejection heat exchanger and a location upstream with respect to refrigerant flow of said refrigeration heat absorption heat exchanger and downstream of said primary expansion device, said hot gas bypass line bypassing said refrigerant heat rejection heat exchanger and said primary expansion device; and   a refrigerant vapor flow control device interdisposed in said hot gas bypass line, said refrigerant flow control device having at least a first open position in which refrigerant vapor flow may pass through said hot gas bypass line and a closed position in which refrigerant vapor flow may not pass through said hot gas bypass line.   
     
     
         2 . The refrigerant vapor compression system as recited in  claim 1  wherein the hot gas bypass line opens into a mid-stage of the compression device to receive refrigerant vapor from the compression device at an intermediate pressure between a compression device suction pressure and a compression device discharge pressure. 
     
     
         3 . The refrigerant vapor compression system as recited in  claim 1  wherein the hot gas bypass line opens into the primary refrigerant circuit at a location between an inlet to the refrigerant heat rejection heat exchanger and a refrigerant vapor discharge outlet of the compression device to receive refrigerant vapor at a compression discharge pressure. 
     
     
         4 . The refrigerant vapor compression system as recited in  claim 1  wherein said refrigerant flow control device comprises a solenoid valve. 
     
     
         5 . The refrigerant vapor compression system as recited in  claim 1  wherein said refrigerant flow control device comprises an expansion valve. 
     
     
         6 . The refrigerant vapor compression system as recited in  claim 1  further comprising a suction modulation valve interdisposed in said refrigerant circuit downstream of said refrigerant heat absorption heat exchanger and upstream of the compression device. 
     
     
         7 . The refrigerant vapor compression system as recited in  claim 1  wherein said system operates in a transcritical cycle. 
     
     
         8 . The refrigerant vapor compression system as recited in  claim 1  wherein the refrigerant comprises carbon dioxide. 
     
     
         9 . The refrigerant vapor compression system as recited in  claim 1  wherein the hot gas bypass line opens into a mid-stage located between a first independent compression stage and a second independent compression stage. 
     
     
         10 . The refrigerant vapor compression system as recited in  claim 1  further comprising a controller for modulating said refrigerant vapor flow control device to selectively vary the opening of a flow passage through said refrigeration vapor flow control device when operating said refrigerant vapor compression system in one of a heating mode or a defrost mode. 
     
     
         11 . The refrigerant vapor compression system as recited in  claim 10  wherein said controller modulates said refrigerant vapor flow control device to selectively vary the opening of a flow passage through said refrigeration vapor flow control device in response to a sensed compressor discharge refrigerant temperature. 
     
     
         12 . A method for controlling the capacity of a refrigerant vapor compression system operating in one of a heating mode and a defrost mode, the refrigerant vapor compression system including a refrigerant circuit having a compression device, a refrigerant heat rejection heat exchanger, and a refrigerant heat absorption heat exchanger disposed in serial refrigerant flow relationship, said method comprising the steps of:
 bypassing refrigerant vapor through a bypass line from a location upstream of the refrigerant heat rejection heat exchanger directly to the refrigerant heat absorption heat exchanger;   disposing a refrigerant vapor flow control device in the bypass line;   disposing a suction modulation valve in a refrigerant line connecting a refrigerant outlet of the refrigerant heat absorption heat exchanger in refrigerant flow communication with a suction inlet of the compression device;   selectively modulating the flow of refrigerant vapor through the refrigerant flow control device; and   selectively modulating the flow of refrigerant through the suction modulation valve.   
     
     
         13 . The method as recited in  claim 12  further comprising the steps of:
 sensing a compressor discharge refrigerant pressure; 
 selectively modulating the flow of refrigerant vapor through the refrigerant flow control device in response to the sensed compressor discharged refrigerant pressure; and 
 selectively modulating the flow of refrigerant through the suction modulation valve to control refrigerant mass flow.