Refrigeration apparatus

Abstract

A refrigeration apparatus includes a compression mechanism, a heat source-side heat exchanger, a usage-side heat exchanger, a switching mechanism and an intermediate heat exchanger. Refrigerant discharged from a first-stage compression element is sequentially compressed by a second-stage compression element. Each of the heat source-side heat exchanger and the usage-side heat exchanger functions an evaporator or radiator. The switching mechanism is configured to switch between a cooling operation state and a heating operation state. The intermediate heat exchanger is configured to cool refrigerant discharged from the first-stage compression element and drawn into the second-stage compression element when the switching mechanism has been set to the cooling operation state, and to evaporate refrigerant whose heat is radiated in the usage-side heat exchanger when the switching mechanism has been set to the heating operation state.

1 . A refrigeration apparatus, comprising:
 a compression mechanism having a plurality of compression elements arranged and configured so that refrigerant discharged from a first-stage compression element of the plurality of compression elements is sequentially compressed by a second-stage compression element of the plurality of compression elements;   a heat source-side heat exchanger arranged and configured to function as a radiator or evaporator of refrigerant;   a usage-side heat exchanger arranged and configured to function as an evaporator or radiator of refrigerant;   a switching mechanism arranged and configured to switch between
 a cooling operation state in which refrigerant is sequentially circulated through the compression mechanism, the heat source-side heat exchanger functioning as a refrigerant radiator, and the usage-side heat exchanger functioning as an evaporator of refrigerant; and 
 a heating operation state in which refrigerant is sequentially circulated through the compression mechanism, the usage-side heat exchanger functioning as a refrigerant radiator, and the heat source-side heat exchanger functioning as an evaporator of refrigerant; and 
   an intermediate heat exchanger arranged and configured to
 cool refrigerant discharged from the first-stage compression element and drawn into the second-stage compression element when the switching mechanism has been set to the cooling operation state, and 
 evaporate refrigerant whose heat is radiated in the usage-side heat exchanger when the switching mechanism has been set to the heating operation state. 
   
     
     
         2 . The refrigeration apparatus according to  claim 1 , further comprising
 an intake return tube arranged and configured to connect one end of the intermediate heat exchanger with an intake side of the compression mechanism;   an intermediate heat exchanger return tube arranged and configured to connect the other end of the intermediate heat exchanger with a portion between the usage-side heat exchanger and the heat source-side heat exchanger; and   an intermediate heat exchanger bypass tube connected to the intermediate refrigerant tube so as to bypass the intermediate heat exchanger,   the intermediate heat exchanger having an intermediate refrigerant tube arranged and configured to draw refrigerant discharged from the first-stage compression element into the second-stage compression element.   
     
     
         3 . The refrigeration apparatus according to  claim 2 , wherein
 at a start of an operation, which sets the switching mechanism to the cooling operation state,
 the refrigerant discharged from the first-stage compression element is drawn into the second-stage compression element through the intermediate heat exchanger bypass tube, and 
 the intermediate heat exchanger is connected with the intake side of the compression mechanism through the intake return tube. 
   
     
     
         4 . The refrigeration apparatus according to  claim 2 , wherein
 the intermediate heat exchanger return tube has a flow rate control valve.   
     
     
         5 . The refrigeration apparatus according to  claim 1 , further comprising
 an expansion device arranged and configured to isentropically expand refrigerant flowing between the heat source-side heat exchanger and the usage-side heat exchanger,   the expansion device being connected to a portion between the heat source-side heat exchanger and the usage-side heat exchanger via a rectifier circuit, and   the rectifier circuit being arranged and configured to rectify refrigerant flow so that refrigerant flows in from an inlet of the expansion device both in cases in which refrigerant flows from the heat source-side heat exchanger to the usage-side heat exchanger and cases in which refrigerant flows from the usage-side heat exchanger to the heat source-side heat exchanger.   
     
     
         6 . The air-conditioning apparatus according to  claim 5 , further comprising
 a gas-liquid separator arranged and configured to perform gas-liquid separation of refrigerant, the gas-liquid separator being connected to an outlet of the expansion device; and   a second-stage injection tube arranged and configured to return to the second-stage compression element gas refrigerant separated in the gas-liquid separator, the second-stage injection tube being connected to the gas-liquid separator.   
     
     
         7 . The refrigeration apparatus according to  claim 3 , wherein
 the intermediate heat exchanger return tube has a flow rate control valve.   
     
     
         8 . The refrigeration apparatus according to  claim 7 , further comprising
 an expansion device arranged and configured to isentropically expand refrigerant flowing between the heat source-side heat exchanger and the usage-side heat exchanger,   the expansion device being connected to the portion between the heat source-side heat exchanger and the usage-side heat exchanger via a rectifier circuit, and   the rectifier circuit being arranged and configured to rectify refrigerant flow so that refrigerant flows in from an inlet of the expansion device both in cases in which refrigerant flows from the heat source-side heat exchanger to the usage-side heat exchanger and cases in which refrigerant flows from the usage-side heat exchanger to the heat source-side heat exchanger.   
     
     
         9 . The air-conditioning apparatus according to  claim 8 , further comprising
 a gas-liquid separator arranged and configured to perform gas-liquid separation of refrigerant, the gas-liquid separator being connected to an outlet of the expansion device; and   a second-stage injection tube arranged and configured to return to the second-stage compression element gas refrigerant separated in the gas-liquid separator, the second-stage injection tube being connected to the gas-liquid separator.   
     
     
         10 . The refrigeration apparatus according to  claim 3 , further comprising
 an expansion device arranged and configured to isentropically expand refrigerant flowing between the heat source-side heat exchanger and the usage-side heat exchanger,   the expansion device being connected to the portion between the heat source-side heat exchanger and the usage-side heat exchanger via a rectifier circuit, and   the rectifier circuit being arranged and configured to rectify refrigerant flow so that refrigerant flows in from an inlet of the expansion device both in cases in which refrigerant flows from the heat source-side heat exchanger to the usage-side heat exchanger and cases in which refrigerant flows from the usage-side heat exchanger to the heat source-side heat exchanger.   
     
     
         11 . The air-conditioning apparatus according to  claim 10 , further comprising
 a gas-liquid separator arranged and configured to perform gas-liquid separation of refrigerant, the gas-liquid separator being connected to an outlet of the expansion device; and   a second-stage injection tube arranged and configured to return to the second-stage compression element gas refrigerant separated in the gas-liquid separator, the second-stage injection tube being connected to the gas-liquid separator.   
     
     
         12 . The refrigeration apparatus according to  claim 4 , further comprising
 an expansion device arranged and configured to isentropically expand refrigerant flowing between the heat source-side heat exchanger and the usage-side heat exchanger,   the expansion device being connected to the portion between the heat source-side heat exchanger and the usage-side heat exchanger via a rectifier circuit, and   the rectifier circuit being arranged and configured to rectify refrigerant flow so that refrigerant flows in from an inlet of the expansion device both in cases in which refrigerant flows from the heat source-side heat exchanger to the usage-side heat exchanger and cases in which refrigerant flows from the usage-side heat exchanger to the heat source-side heat exchanger.   
     
     
         13 . The air-conditioning apparatus according to  claim 12 , further comprising
 a gas-liquid separator arranged and configured to perform gas-liquid separation of refrigerant, the gas-liquid separator being connected to an outlet of the expansion device; and   a second-stage injection tube arranged and configured to return to the second-stage compression element gas refrigerant separated in the gas-liquid separator, the second-stage injection tube being connected to the gas-liquid separator.   
     
     
         14 . The refrigeration apparatus according to  claim 2 , further comprising
 an expansion device arranged and configured to isentropically expand refrigerant flowing between the heat source-side heat exchanger and the usage-side heat exchanger,   the expansion device being connected to the portion between the heat source-side heat exchanger and the usage-side heat exchanger via a rectifier circuit, and   the rectifier circuit being arranged and configured to rectify refrigerant flow so that refrigerant flows in from an inlet of the expansion device both in cases in which refrigerant flows from the heat source-side heat exchanger to the usage-side heat exchanger and cases in which refrigerant flows from the usage-side heat exchanger to the heat source-side heat exchanger.   
     
     
         15 . The air-conditioning apparatus according to  claim 14 , further comprising
 a gas-liquid separator arranged and configured to perform gas-liquid separation of refrigerant, the gas-liquid separator being connected to an outlet of the expansion device; and   a second-stage injection tube arranged and configured to return to the second-stage compression element gas refrigerant separated in the gas-liquid separator, the second-stage injection tube being connected to the gas-liquid separator.