Compressor oil injection cooling

Abstract

A working fluid circuit includes a compressor, an oil sump, and an oil injection system. The compressor compresses working fluid into a compressed working fluid. The oil injection system has an oil pathway that is connected to the oil sump and to a suction pathway of the compressor. The oil pathway injects the oil from the oil sump into the suction pathway to cool the working fluid in the suction pathway. A method of controlling a working fluid circuit includes suctioning working fluid into a compressor, compressing the working fluid, and discharging the working fluid from the compressor. The method also includes separating oil from the working fluid and supplying and injecting, via an oil pathway, the oil into a suction pathway of the compressor. Gaseous refrigerant dissolved in the oil is liberated from the oil to provide cooling to the working fluid in the suction pathway.

What is claimed is: 
     
         1 . A working fluid circuit, comprising:
 a compressor including a suction inlet, a discharge outlet, and one or more compression chambers connecting the suction inlet to the discharge outlet and configured to compress working fluid;   an oil sump configured to contain oil separated from the working fluid; and   an oil injection system with an oil pathway connected to the oil sump and to a suction pathway of the compressor, the suction pathway including the suction inlet, the oil pathway configured to inject the oil from the oil sump into the suction pathway to cool the working fluid in the suction pathway flowing to the one or more compression chambers.   
     
     
         2 . The working fluid circuit of  claim 1 , wherein the oil pathway injects the oil into the suction pathway at a higher pressure than the working fluid in the suction pathway, such that gaseous refrigerant dissolved in the portion of the oil is liberated from the oil and cools the oil. 
     
     
         3 . The working fluid circuit of  claim 1 , wherein the oil pathway includes an oil pump, the oil pump configured to direct the oil from the oil sump into and through the oil pathway to inject the oil into the suction pathway of the compressor. 
     
     
         4 . The working fluid circuit of  claim 1 , wherein the oil pathway includes a restriction, the restriction configured to compress the oil as the oil in the oil pathway flows through the restriction. 
     
     
         5 . The working fluid circuit of  claim 1 , wherein the injection of the oil into the suction pathway by the oil pathway is configured to decrease a discharge temperature of the compressed working fluid discharged from the compressor by at least 5°F. 
     
     
         6 . The working fluid circuit of  claim 1 , wherein the injection of the oil into the suction pathway by the oil pathway is configured to decrease a discharge temperature of the compressed working fluid from the compressor by at least 10°F. 
     
     
         7 . The working fluid circuit of  claim 1 , wherein the compressor includes the oil sump. 
     
     
         8 . The working fluid circuit of  claim 1 , further comprising:
 an oil separator connected to the discharge outlet of the compressor, the oil separator configured to receive the compressed working fluid that contains the oil and to separate the oil therefrom.   
     
     
         9 . The working fluid circuit of  claim 1 , wherein the compressor including a suction plenum for the one or more compression chambers, the suction inlet connecting to the suction plenum, and an outlet of the oil pathway connects to the suction pathway at a suction plenum of the compressor such that the suction pathway injects the oil into the suction pathway at the suction plenum. 
     
     
         10 . The working fluid circuit of  claim 1 , further comprising:
 an oil heat exchanger configured to cool one or more of:
 the oil flowing through the oil pathway, and 
 the oil in the oil sump. 
   
     
     
         11 . The working fluid circuit of  claim 10 , wherein the oil heat exchanger is configured to cool the oil by at least 50°C. 
     
     
         12 . The working fluid circuit of  claim 1 , wherein the working fluid circuit has an oil circulation rate of 10% or less. 
     
     
         13 . The working fluid circuit of  claim 1 , wherein the working fluid contains A2L refrigerant. 
     
     
         14 . A method of controlling a working fluid circuit including a compressor, the method comprising:
 suctioning a working fluid into the compressor;   compressing, within the compressor, the working fluid into a compressed working fluid;   discharging the compressed working fluid from the compressor;   directing oil from the working fluid into an oil sump;   supplying, via an oil pathway, the oil from the oil sump into a suction pathway of the compressor, which includes:
 injecting the oil from the oil pathway into the suction pathway, and 
 liberating gaseous refrigerant dissolved in the oil from the oil to provide cooling to the working fluid in the suction pathway. 
   
     
     
         15 . The method of  claim 14 , wherein the injecting of the oil into the suction pathway decreases a pressure of the oil causing the liberating of the gaseous refrigerant dissolved in the oil from the oil. 
     
     
         16 . The method of  claim 14 , further comprising:
 cooling of the oil prior to the injecting of the oil, which includes one or more of:
 cooling the oil flowing through the oil pathway, and 
 cooling of the oil disposed in the oil sump. 
   
     
     
         17 . The method of  claim 14 , wherein the supplying of the oil, via an oil pathway, from the oil sump into the suction pathway of the compressor decreases a discharge temperature of the compressor by at least 5°F. 
     
     
         18 . The method of  claim 14 , wherein the supplying of the oil, via an oil pathway, from the oil sump into the suction pathway of the compressor decreases a discharge temperature of the compressor by at least 10°F.