Refrigerating Circuit

Abstract

The invention relates to a refrigerating circuit ( 10 ) adapted to circulate, in operation, a refrigerant in a predetermined flow direction, said refrigerating circuit ( 10 ) comprising a compressor stage ( 12 ), said compressor stage ( 12 ) having a suction side and a pressure side, and at least one heat dissipating heat exchanging unit ( 14 ) connected to said pressure side of said compressor stage ( 12 ) via a pressure line ( 24 ), said heat dissipating heat exchanging unit ( 14 ) having an inlet side ( 14 a ) and an outlet side ( 14 b ) and including a condenser/gas cooler unit ( 16 ), and a liquid refrigerant return line ( 26 ) connecting said outlet side of said heat dissipating heat exchanging unit ( 14 ) to said pressure line ( 24 ).

1 . Refrigerating circuit adapted to circulate, in operation, a CO 2  refrigerant in a predetermined flow direction,
 said refrigerating circuit comprising
 a compressor stage, said compressor stage having a suction side and a pressure side, and 
 at least one heat dissipating heat exchanging unit connected to said pressure side of said compressor stage via a pressure line, said heat dissipating heat exchanging unit having an inlet side and an outlet side and including a condenser/gas cooler unit, and 
 a liquid refrigerant return line connecting said outlet side of said heat dissipating heat exchanging unit to said pressure line, 
 wherein said refrigerating circuit includes a first compressor stage assigned to a medium temperature cooling loop, and a second compressor stage assigned to a low temperature cooling loop, and said pressure line connects the pressure side of said second compressor stage via said first compressor stage to said inlet side of said heat dissipating, heat exchanging unit, and 
 wherein said pressure line has a first pressure line portion connecting said first compressor stage and said heat dissipating heat exchanging unit, and a second pressure line portion connecting said second compressor stage and said first compressor stage, said liquid refrigerant return lime opening into said second pressure line portion. 
   
     
     
         2 . Refrigerating circuit according to  claim 1 ,
 wherein said pressure line includes pressure reduction means for locally reducing pressure of said refrigerant in said pressure line from an operational pressure (p c , p c ′) to a reduced pressure (p 1 ) smaller than said operational pressure (p c , p c ′), and said liquid refrigerant return line opens into said pressure line at a position in which said refrigerant has said reduced pressure (p 1 ).   
     
     
         3 . Refrigerating circuit according to  claim 2 ,
 said pressure reduction means includes a venturi structure, said venturi structure being formed such as to locally reduce the cross section of said pressure line.   
     
     
         4 . Refrigerating circuit according to  claim 3 ,
 wherein said venturi structure has an inlet side and an outlet side defining the cross section of said pressure line upstream and downstream of said venturi structure, respectively, said inlet side and said outlet side defining essentially the same cross section.   
     
     
         5 . Refrigerating circuit according to  claim 3 ,
 wherein said venturi structure has an intermediate portion located between an inlet side and an outlet side thereof, said intermediate portion including a first tapered portion extending from said inlet side, and a second tapered portion extending from said outlet side, axial inner sides of said first and second tapered portions defining said reduced cross section of said pressure line, said first and said second tapered portions having an essentially identical extension in axial direction.   
     
     
         6 . Refrigerating circuit according to  claim 5 ,
 wherein said axial inner sides of said first and second tapered portions are connected by a non-tapered central portion, said liquid refrigerant return line opening into said central portion.   
     
     
         7 . Refrigerating circuit according to  claim 6 ,
 wherein said central portion essentially has the same extension in axial direction as said first and/or second tapered portions.   
     
     
         8 . (canceled) 
     
     
         9 . Refrigerating circuit according to  claim 1 ,
 wherein said refrigerating circuit includes a single compressor stage.   
     
     
         10 .- 11 . (canceled) 
     
     
         12 . Refrigerating circuit according to  claim 1 , wherein said liquid refrigerant return line includes a valve, said valve being controlled according to a superheating state of said refrigerant in said pressure line. 
     
     
         13 . Refrigerating circuit according to  claim 1 ,
 wherein said valve is controlled by a thermostat unit.   
     
     
         14 . Refrigerating circuit according to  claim 1 ,
 wherein said heat dissipating heat exchanging unit includes a receiver connected in series to said condenser/gas cooler unit, said receiver having an upstream side connected to an outlet side of said condenser/gas cooler unit, said liquid refrigerant return line opening at a downstream side of said receiver.