Economized Vapor Compression Circuit

Abstract

An economized vapor compression circuit is disclosed. An evaporator, compressor, condenser and economizer are fluidly connected by a refrigerant line containing refrigerant. A portion of the liquid refrigerant leaving the economizer is diverted away from the evaporator to sub-cool liquid refrigerant at a location between the condenser and the evaporator.

1 . An economized vapor compression circuit comprising:
 an evaporator;   a compressor;   a condenser; and   an economizer,   wherein the evaporator, compressor, condenser and economizer are fluidly connected by a refrigerant line containing refrigerant, wherein liquid refrigerant leaving the economizer is split into a first stream and second stream,   wherein, at a location intermediate the condenser and the evaporator, the first stream of refrigerant flows in a heat exchange relationship with refrigerant to be provided to the evaporator in which the first stream of liquid refrigerant expands and evaporates, subcooling the refrigerant to be provided to the evaporator, and   wherein the second stream of liquid refrigerant flows to the evaporator.   
   
   
       2 . The vapor compression circuit of  claim 1 , wherein the economizer is a heat exchanger and wherein substantially all refrigerant flows from the condenser to a first side of the heat exchanger and wherein the first stream of liquid refrigerant flows to a second side of the heat exchanger, wherein the first stream of liquid refrigerant is in the heat exchange relationship with and sub-cools the refrigerant entering the first side of the heat exchanger. 
   
   
       3 . The vapor compression circuit of  claim 2 , wherein the refrigerant flowing to the first side of the heat exchanger from the condenser is a saturated liquid. 
   
   
       4 . The vapor compression circuit of  claim 2 , wherein the refrigerant flowing to the first side of the heat exchanger from the condenser is a liquid/vapor mixture. 
   
   
       5 . The vapor compression circuit of  claim 2 , wherein the refrigerant flowing to the first side of the heat exchanger from the condenser has less than about 5° F. of sub-cooling. 
   
   
       6 . The vapor compression circuit of  claim 2 , wherein the economizer heat exchanger is selected from the group consisting of a shell and tube heat exchanger, a plate heat exchanger and a tube in tube heat exchanger. 
   
   
       7 . The vapor compression circuit of  claim 1 ,
 wherein the economizer is a flash tank having a liquid refrigerant outlet and a gaseous refrigerant outlet and the vapor compression circuit further comprises a heat exchanger intermediate the flash tank and the evaporator,   wherein the second stream of liquid refrigerant flows to a first side of the heat exchanger and the first stream of liquid refrigerant flows to a second side of the heat exchanger, the first stream in the heat exchange relationship with the second stream, sub-cooling the second stream of refrigerant in the first side of the heat exchanger.   
   
   
       8 . The vapor compression circuit of  claim 1 , wherein the evaporated first stream of refrigerant is fluidly connected to the compressor. 
   
   
       9 . The vapor compression circuit of  claim 1 , wherein the circuit further comprises a second compressor to receive the evaporated first stream of refrigerant. 
   
   
       10 . The vapor compression circuit of  claim 1 , wherein the condenser is a heat exchanger selected from the group consisting of a multi-channel heat exchanger, fin and tube heat exchanger, and water cooled heat exchanger. 
   
   
       11 . The vapor compression circuit of  claim 1 , wherein the evaporator is a heat exchanger selected from the group consisting of a multi-channel heat exchanger, fin and tube heat exchanger, and water cooled heat exchanger. 
   
   
       12 . The vapor compression circuit of  claim 1 , wherein the compressor is selected from the group consisting of rotary compressors, screw compressors, reciprocating compressors, centrifugal compressors, swing link compressors, scroll compressors, and turbine compressors. 
   
   
       13 . The vapor compression circuit of  claim 1  further comprising a receiver fluidly connected intermediate the economizer and the evaporator. 
   
   
       14 . The vapor compression circuit of  claim 1  further comprising an expansion device fluidly connected between a liquid outlet of the economizer and the evaporator. 
   
   
       15 . The vapor compression circuit of  claim 1  wherein the first stream is in the range of about 10% to about 20% by mass of the liquid refrigerant leaving the economizer. 
   
   
       16 . A method for operating a vapor compression circuit comprising:
 providing a refrigerant circuit comprising
 a condenser, an evaporator, an economizer, an expansion device, and a compressor fluidly connected by a refrigerant line containing refrigerant; 
   directing substantially all refrigerant leaving the condenser to a first side of the economizer;   diverting a minority portion of liquid refrigerant leaving the first side of the economizer to a second side of the economizer to exchange heat with refrigerant in the first side of the economizer; and   sub-cooling refrigerant in the first side of the economizer.   
   
   
       17 . The method of  claim 16 , wherein the diverted minority portion of liquid refrigerant is in the range of about 10% to about 20% by mass of the liquid refrigerant leaving the first side of the economizer. 
   
   
       18 . The method of  claim 16 , wherein the step of providing further comprises providing a receiver fluidly connected along the refrigerant line intermediate the economizer and the expansion device, and wherein the step of diverting comprises diverting liquid refrigerant from the receiver. 
   
   
       19 . The method of  claim 16 , wherein the refrigerant leaving the condenser has less than 5° F. of sub-cooling. 
   
   
       20 . A vapor compression circuit comprising:
 a compressor, a condenser, an economizer, an expansion device and an evaporator connected in a closed refrigeration loop; and   the economizer being configured to receive all refrigerant leaving the condenser and to provide sub-cooled liquid refrigerant to the evaporator;   a portion of the liquid refrigerant leaving the economizer being diverted back to the economizer to exchange heat with the refrigerant entering the economizer from the condenser to sub-cool refrigerant being provided to the evaporator.   
   
   
       21 . The vapor compression cycle of  claim 20 , wherein the portion of the refrigerant being diverted back to the economizer is about 10% to about 20% by mass of the refrigerant received from the condenser 
   
   
       22 . The vapor compression cycle of  claim 20 , wherein the economizer is a heat exchanger selected from the group consisting of a shell and tube heat exchanger, a plate heat exchanger and a tube and tube heat exchanger. 
   
   
       23 . An economized vapor compression circuit comprising:
 a compressor, a condenser, a flash tank economizer, an expansion device and an evaporator connected in a closed refrigeration loop;   the flash tank economizer being configured to receive refrigerant from the condenser and provide refrigerant to the evaporator; and   a heat exchanger intermediate the flash tank and the evaporator, wherein liquid refrigerant leaving the flash tank is split into a first stream and a second stream, wherein the second stream is to be provided to the evaporator and wherein the first stream and the second stream are directed to different sides of the heat exchanger such that the first stream enters into a heat exchange relationship with the second stream, to subcool the second stream prior to being provided to the evaporator.