Refrigeration circuit with improved liquid/vapour receiver

Abstract

Refrigeration circuit comprising a compressor, a heat-rejecting heat exchanger an expansion valve, a receiver ( 3 ), and a further expansion valve/evaporator to provide cooling. A second heat exchanger ( 24 ) is arranged in an upper gas portion of the receiver and/or a third heat exchanger ( 34 ) is arranged in a lower liquid portion of the receiver. A better liquid/vapour separation of the refrigerant and/or sub-cooling of the liquid refrigerant are achieved.

1 . Refrigeration circuit for circulating a refrigerant in a predetermined flow direction, comprising in flow direction a first compressor device, a heat-rejecting heat exchanger, a first expansion device, a receiver having in its interior an upper portion, being in flow communication with the first expansion device, and a lower portion, a second expansion device being in flow communication with the lower portion of the receiver, and a first evaporator; and comprising a further flow path between the upper portion of the receiver and the suction side of a compressor, the pressure side of which is in flow communication with the entrance of said heat-rejecting heat exchanger; wherein at least one element of the group consisting of the following elements (a) and (b) is provided:
 (a) a second heat exchanger is arranged in said upper portion of said receiver, the entrance of the second heat exchanger being in flow communication with the exit of said heat-rejecting heat exchanger and the exit of the second heat exchanger being in flow communication with the entrance of said first expansion device,   (b) said further flow path comprises a third expansion device and, downstream thereof, a third heat exchanger arranged in said lower portion of said receiver.   
   
   
       2 . Refrigeration circuit according to  claim 1 , wherein said compressor connected to said further flow path is part of said first compressor device. 
   
   
       3 . Refrigeration circuit according to any one of  claims 1  to  2 , wherein said refrigerant is CO 2 . 
   
   
       4 . Refrigeration circuit according to any one of  claims 1  to  3 , wherein said first compressor device comprises a parallel group of several compressors. 
   
   
       5 . Refrigeration circuit according to any one of  claims 1  to  4 , further comprising a branch circuit, branching off from a location located in a section of said circuit which section extends from said lower portion of said receiver to the entrance of said second expansion device; the branch circuit comprising in flow direction a fourth expansion device, a second evaporator, and a second compressor device; and the branch circuit, at its downstream end, being in flow communication with the suction side of said first compressor device. 
   
   
       6 . Refrigeration circuit according to any one of  claims 1  to  5 , wherein several parallel first evaporators are provided. 
   
   
       7 . Refrigeration apparatus comprising a refrigeration circuit as specified in any one of  claims 1  to  6 . 
   
   
       8 . Refrigeration method, comprising:
 (a) circulating a refrigerant in a refrigeration circuit comprising, in flow direction, a first compressor device, a heat-rejecting heat exchanger, a first expansion device, a receiver having in its interior an upper portion, being in flow communication with the first expansion device, and a lower portion, a second expansion device being in flow communication with the lower portion of the receiver, and a first evaporator;   (b) the refrigeration circuit further comprising a further flow path provided between the upper portion of the receiver and the suction side of a compressor, the pressure side of which is in fluid communication with the entrance of said heat-rejecting heat exchanger;   (c) said refrigeration method comprising at least one step of the group of steps consisting of
 (i) operating a heat source in said upper portion of said receiver, 
 (ii) operating a heat sink in said lower portion of said receiver. 
   
   
   
       9 . Refrigeration method according to  claim 8 , wherein the refrigerant is CO 2 .