Refrigeration Apparatus

Abstract

A refrigeration apparatus having a refrigerant circuit ( 20 ) for performing a vapor compression refrigeration cycle is disclosed. Refrigerant in a wet state, which provides an optimum coefficient of performance (COP) for a present operating condition, is drawn into the compressor ( 31 ). If the operating condition changes, the opening of an expansion valve ( 23 ) is adjusted such that the suction refrigerant of the compressor ( 31 ) is brought into a wet state which provides an optimum coefficient of performance for a new operating condition.

1 . A refrigeration apparatus comprising a refrigerant circuit ( 20 ) for performing a refrigeration cycle which circuit includes a compressor ( 31 ),
 wherein:   refrigerant in a wet state, which provides an optimum coefficient of performance (COP) for a present operating state, is drawn into the compressor ( 31 ).   
   
   
       2 . A refrigeration apparatus comprising a refrigerant circuit ( 20 ) for performing a refrigeration cycle which circuit includes a compressor ( 31 ),
 wherein:   refrigerant in a superheated state is drawn into the compressor ( 31 ) during a cooling operation mode and the refrigerant in a wet state is drawn into the compressor ( 31 ) during a heating operation mode.   
   
   
       3 . A refrigeration apparatus comprising a refrigerant circuit ( 20 ) for performing a refrigeration cycle which circuit includes a compressor ( 31 ),
 wherein:   a target discharge temperature for the compressor ( 31 ) is set so as to obtain an optimum coefficient of performance (COP) for a present operating state and refrigerant in a wet state, which makes the discharge temperature of the compressor ( 31 ) equal to the target discharge temperature, is drawn into the compressor ( 31 ).   
   
   
       4 . The refrigeration apparatus according to any one of  claims 1  to  3 ,
 wherein:   the refrigerant circuit ( 20 ) is provided with an expansion valve ( 23 ) and the wet state of suction refrigerant of the compressor ( 31 ) is controlled by adjusting the opening of the expansion valve ( 23 ).   
   
   
       5 . The refrigeration apparatus according to any one of  claim 1  to  3 ,
 wherein:   the refrigerant circuit ( 20 ) has a gas-liquid separator ( 25 ) disposed between evaporators ( 22 ,  24 ) and the suction side of the compressor ( 31 );   the gas-liquid separator ( 25 ) includes a liquid injection pipe ( 26 ) having a flow rate control valve ( 27 ), for guiding liquid refrigerant from the gas-liquid separator ( 25 ) to the suction side of the compressor ( 31 ); and   the wet state of suction refrigerant of the compressor ( 31 ) is controlled by adjusting the flow rate control valve ( 27 ).   
   
   
       6 . The refrigeration apparatus according to any one of  claims 1  to  3 ,
 wherein:   the refrigerant circuit ( 20 ) has an expander ( 33 ) mechanically connected to the compressor ( 31 ) through a motor ( 32 ) of the compressor ( 31 );   the refrigerant circuit ( 20 ) includes a bypass pipe ( 44 ) through which a part of the refrigerant flowing to the expander ( 33 ) flows, bypassing the expander ( 33 ), and a flow rate control valve ( 45 ) provided in the bypass pipe ( 44 ); and   the wet state of suction refrigerant of the compressor ( 31 ) is controlled by adjusting the flow rate control valve ( 45 ).   
   
   
       7 . The refrigeration apparatus according to any one of  claims 1  to  3 ,
 wherein:   the refrigerant circuit ( 20 ) is configured such that the high pressure of the refrigeration cycle is higher than the critical pressure of the refrigerant.   
   
   
       8 . The refrigeration apparatus according to  claim 7 ,
 wherein:   the refrigerant is carbon dioxide.