Co2 refrigerant system with booster circuit

Abstract

A refrigerant system, which utilizes CO 2 as a refrigerant, includes a main closed-loop refrigerant circuit and a booster closed-loop refrigerant circuit. A heat accepting heat exchanger, which provides extra cooling for the refrigerant circulating through the main circuit, and thus improves refrigerant system performance, also serves as a shared component coupling the two circuits through heat transfer interaction. Various schematics and configurations for the booster circuit, which may be combined with other performance enhancement features, are disclosed. Additional benefits for economizer function, “liquid-to-suction” heat exchanger, intercooling and liquid injection are also presented. The booster circuit may also contain CO 2 refrigerant.

1 . A refrigerant system comprising:
 a main closed-loop refrigerant circuit including a compressor for compressing refrigerant and delivering it downstream to a heat rejection heat exchanger, refrigerant from said heat rejection heat exchanger passing through an expansion device, then through an evaporator and returning to said compressor; and   a booster closed-loop refrigerant circuit, said booster circuit including a compressor, a first heat exchanger to reject heat from said booster circuit, an expansion device and a heat accepting heat exchanger, and refrigerant in said booster circuit cooling refrigerant in said main circuit in said heat accepting heat exchanger, said main circuit being charged with CO 2  refrigerant.   
   
   
       2 . The refrigerant system as set forth in  claim 1 , wherein said heat accepting heat exchanger and said heat rejection heat exchanger for said main circuit comprise a single heat exchanger unit. 
   
   
       3 . The refrigerant system as set forth in  claim 2 , wherein said heat accepting heat exchanger is a shell-and-tube heat exchanger and is incorporated into an outlet manifold of said heat rejection heat exchanger. 
   
   
       4 . The refrigerant system as set forth in  claim 1 , wherein said booster circuit and said main circuit are being charged with different refrigerants. 
   
   
       5 . The refrigerant system as set forth in  claim 1 , wherein said booster circuit is also being charged with CO 2  refrigerant. 
   
   
       6 . The refrigerant system as set forth in  claim 1 , wherein said first heat exchanger for said booster circuit and said heat rejection heat exchanger are aligned such that a single air-moving device can be utilized to move air over both heat exchangers. 
   
   
       7 . The refrigerant system as set forth in  claim 6 , wherein said first heat exchanger for said booster circuit and said heat rejection heat exchanger comprise a single heat exchanger unit. 
   
   
       8 . The refrigerant system as set forth in  claim 1 , wherein said main circuit compressor and said booster circuit compressor comprise a single compressor unit. 
   
   
       9 . The refrigerant system as set forth in  claim 8 , wherein said main circuit compressor and said booster circuit compressor are represented by different banks of cylinders of the same reciprocating compressor. 
   
   
       10 . The refrigerant system as set forth in  claim 1 , wherein said first heat exchanger of said booster circuit is utilized for heating purposes. 
   
   
       11 . The refrigerant system as set forth in  claim 1 , wherein refrigerant downstream of said evaporator in said main circuit also passes through said heat accepting heat exchanger before being returned to said compressor. 
   
   
       12 . The refrigerant system as set forth in  claim 11 , wherein said heat accepting heat exchanger is a three-stream refrigerant-to-refrigerant heat exchanger. 
   
   
       13 . The refrigerant system as set forth in  claim 12 , wherein all three refrigerant streams are arranged in parallel relationship. 
   
   
       14 . The refrigerant system as set forth in  claim 12 , wherein two refrigerant streams of said main circuit ale arranged in sequence With each other and in parallel to the refrigerant stream of said booster circuit. 
   
   
       15 . The refrigerant system as set forth in  claim 12 , wherein said heat accepting heat exchanger consists of two heat exchanger units arranged in sequence with respect to refrigerant flow in said main circuit. 
   
   
       16 . The refrigerant system as set forth in  claim 1 , wherein said main circuit is provided with an economizer function. 
   
   
       17 . The refrigerant system as set forth in  claim 16 , wherein said heat accepting heat exchanger of said booster circuit is also utilized as an economizer heat exchanger of said economizer function. 
   
   
       18 . The refrigerant system as set forth in  claim 17 , wherein said heat accepting heat exchanger is a three-stream refrigerant-to-refrigerant heat exchanger. 
   
   
       19 . The refrigerant system as set forth in  claim 18 , wherein all three refrigerant streams are arranged in parallel relationship. 
   
   
       20 . The refrigerant system as set forth in  claim 1 , wherein said main circuit is provided with an intercooler heat exchanger; and
 said heat accepting heat exchanger of said booster circuit also being utilized as an intercooler heat exchanger.