Refrigerant Circuit And Method For Operating A Refrigerant Circuit

Abstract

There is provided a refrigerant circuit comprising a compressor ( 10 ), a condenser or gas cooler ( 12 ), an ejector ( 16 ) with a high-pressure connection and a suction connection, a pre-evaporator ( 18 ), a separator ( 20 ) with a liquid phase output and a gas phase output, a low-temperature evaporator ( 28 ) which is arranged between the liquid phase output of the separator ( 20 ) and the suction connection, and a superheating evaporator ( 24 ) which is arranged between the gas phase output of the separator ( 20 ) and the suction side of the compressor ( 10 ). A method for operating a refrigerant circuit provides for expanding condensed or supercritical refrigerant in an ejector ( 16 ), then pre-evaporating it, then separating the predominantly liquid phase from the predominantly gaseous phase, further evaporating the predominantly liquid phase and supplying it to a suction connection of the ejector ( 18 ), and completely evaporating the predominantly gaseous phase before supplying it to a compressor ( 10 ).

1 . A refrigerant circuit comprising a compressor ( 10 ), a condenser or gas cooler ( 12 ), an ejector ( 16 ) with a high-pressure connection and a suction connection, a pre-evaporator ( 18 ), a separator ( 20 ) with a liquid phase output and a gas phase output, a low-temperature evaporator ( 28 ) which is arranged between the liquid phase output of the separator ( 20 ) and the suction connection ( 30 ) of the ejector ( 16 ), and a superheating evaporator ( 24 ) which is arranged between the gas phase output of the separator ( 20 ) and a suction side of the compressor ( 10 ). 
     
     
         2 . A refrigerant circuit according to  claim 1 , characterised in that the evaporators ( 18 ,  24 ,  28 ) are flowed through by a heat transfer medium which flows through a heat exchanger ( 36 ). 
     
     
         3 . A refrigerant circuit according to  claim 2 , characterised in that the evaporators ( 18 ,  24 ,  28 ) are counterflow evaporators ( 18 ,  24 ,  28 ). 
     
     
         4 . A refrigerant circuit according to  claim 2 , characterised in that the heat transfer medium is water or a mixture of water and glycol. 
     
     
         5 . A refrigerant circuit according to  claim 2 , characterised in that the heat exchanger ( 36 ) is part of an air conditioning device. 
     
     
         6 . A refrigerant circuit according to  claim 2 , characterised in that the heat exchanger ( 36 ) is a cross-counterflow heat exchanger. 
     
     
         7 . A refrigerant circuit according to  claim 1 , characterised in that the pre-evaporator ( 18 ) is arranged upstream of the separator ( 20 ) relative to the flow direction of the refrigerant. 
     
     
         8 . A refrigerant circuit according to  claim 1 , characterised in that the low-temperature evaporator ( 28 ) and/or the superheating evaporator ( 24 ) is/are arranged upstream of the separator ( 20 ) relative to the flow direction of the refrigerant. 
     
     
         9 . A refrigerant circuit according to  claim 1 , characterised in that the pre-evaporator ( 18 ), the low-temperature evaporator ( 28 ) and/or the superheating evaporator ( 24 ) form a one-piece evaporating element ( 14 ). 
     
     
         10 . A refrigerant circuit according to  claim 9 , characterised in that the ejector ( 16 ) is integrated in the one-piece evaporating element ( 14 ). 
     
     
         11 . A refrigerant circuit according to  claim 1 , characterised in that it has an internal heat exchanger ( 13 ), by means of which heat can be transferred from the high-pressure side to the low-pressure side. 
     
     
         12 . A refrigerant circuit according to  claim 11 , characterised in that the internal heat exchanger ( 13 ) is combined in an integrated manner in the condenser or gas cooler ( 12 ). 
     
     
         13 . A refrigerant circuit according to  claim 1 , characterised in that the power of each evaporator ( 18 ,  24 ,  28 ) lies in the range between 20 and 40% of the total power of all the evaporators. 
     
     
         14 . A refrigerant circuit according to  claim 1 , characterised in that the compressor ( 10 ) is electrically driven. 
     
     
         15 . A refrigerant circuit according to  claim 1 , characterised in that a nozzle cross section of the ejector ( 16 ) is controllable. 
     
     
         16 . A method for operating a refrigerant circuit, in which condensed or supercritical refrigerant is expanded in an ejector ( 16 ), then is partially evaporated, then the predominantly liquid phase is separated from the predominantly gaseous phase, the predominantly liquid phase is evaporated in a low-temperature evaporator ( 28 ) and is supplied to a suction connection of the ejector ( 16 ), and the predominantly gaseous phase is completely evaporated before being supplied to a compressor ( 10 ). 
     
     
         17 . A method according to  claim 16 , characterised in that the predominantly gaseous phase is superheated. 
     
     
         18 . A method according to  claim 16 , characterised in that the mass flow of the heat transfer medium is controlled in such a way that the temperature difference ΔT WT  of the heat transfer medium between the output and the input of a heat exchanger ( 36 ) is equal to x times the temperature difference ΔT L  of the air between the input and the output of the heat exchanger ( 36 ), wherein x is between 0.7 and 1.3. 
     
     
         19 . A method according to  claim 18 , characterised in that x is between 0.9 and 1.1.