Refrigerating or heat pump system with heat rejection at supercritical pressure

Abstract

A refrigerating or heat pump system includes an evaporator ( 23 ), a compressor ( 20 ), an air-cooled heat rejecting heat exchanger ( 21 ) and an expansion device ( 22 ) being connected in a closed circuit and operating in a trans critical vapor compression cycle. The heat rejecting heat exchanger ( 21 ) is cooled by natural upwards circulation/convention of air. In a preferred embodiment the heat rejecting exchanger ( 21 ) is built into an air flow conduit or shell ( 11 ) to improve the natural air circulation by obtaining a chimney effect.

1 . A refrigerating or heat pump system including at least one of each following components, an evaporator ( 23 ), a compressor ( 20 ), an air-cooled heat rejecting heat exchanger ( 21 ) and an expansion device ( 22 ), connected in a closed circuit operating in a vapor compression cycle, characterized in that the refrigerant rejects heat at a supercritical pressure with gliding temperature through the heat rejecting heat exchanger ( 21 ) which is cooled by natural upwards circulation/convection of air.  
     
     
         2 . A system according to  claim 1 , characterized in that the heat rejecting exchanger ( 21 ) is built into an air flow conduit or shell ( 11 ) to improve the natural air circulation.  
     
     
         3 . A system according to  claim 1  and  2 , characterized in that the air flow conduit ( 11 ) extends upwards in a generally vertical direction  
     
     
         4 . A system according to the preceding claims  1 - 3 , characterized in that the flow of refrigerant through refrigerant pipes or conduits ( 10 ) of the heat rejecting heat exchanger ( 21 ) passes is generally from an inlet ( 12 ) at the top towards an outlet ( 13 ) at the bottom.  
     
     
         5 . A system according to one or more of the preceding claims  1 - 4 , characterized in that an additional air flow conduit ( 11   a ) is installed on top of the heat rejecting heat exchanger ( 21 ) in order to increase the air flow rate.  
     
     
         6 . A system according to one or more of the preceding claims  1 - 5 , characterized in that an additional air flow nozzle arrangement is installed on top of the heat rejecting heat exchanger ( 21 ) in order to increase the air flow rate.  
     
     
         7 . A system according to one or more of the preceding claims  1 - 6 , characterized in that the air flow conduit or shell ( 11 ) is fully or partly used as heat transfer surface whereby the refrigerant pipes or conduits ( 10 ) form an integral part of the conduit or shell ( 11 ).  
     
     
         8 . A system according to one or more of the preceding claims  1 - 7 , characterized in that a fan is installed before, after or inside the air flow conduit ( 11 ) in order to improve air flow at high-load situations.  
     
     
         9 . A system according to one or more of the preceding claims  1 - 8 , characterized in that carbon dioxide is used as irigerant.