Refrigeration apparatus

Abstract

A refrigeration apparatus uses supercritical range refrigerant, and includes a multi-stage compression mechanism, a heat source-side heat exchanger, a usage-side heat exchanger, a switching mechanism switchable between cooling and heating operation states, an intermediate heat exchanger integrated with 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 is connected to an intermediate refrigerant tube to draw refrigerant discharged from the first-stage compression element into the second-stage compression element, and functions as a cooler of the refrigerant discharged from the first-stage compression element and drawn into the second-stage compression element. The intermediate heat exchanger bypass tube ensures that refrigerant does not flow to the intermediate heat exchanger when a reverse cycle defrosting operation is performed.

1 . A refrigeration apparatus that uses a refrigerant that operates in a supercritical range, the 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;   a heat source-side heat exchanger using air as a heat source and being arranged and configured to operate as a radiator or evaporator of refrigerant;   a usage-side heat exchanger arranged and configured to operate an evaporator or radiator of refrigerant;   a switching mechanism arranged and configured to switch between a cooling operation state in which the refrigerant is circulated through the compression mechanism, the heat source-side heat exchanger, and the usage-side heat exchanger in order, and   a heating operation state in which the refrigerant is circulated through the compression mechanism, the usage-side heat exchanger, and the heat source-side heat exchanger in order;   an intermediate heat exchanger integrated with the heat source-side heat exchanger and using air as a heat source, the intermediate heat exchanger
 being connected to an intermediate refrigerant tube to draw refrigerant discharged from the first-stage compression element into the second-stage compression element, and 
 being arranged and configured to cool the refrigerant discharged from the first-stage compression element and drawn into the second-stage compression element; 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 being disposed above the heat source-side heat exchanger, and   the intermediate heat exchanger bypass tube being arranged and configured to ensure that refrigerant does not flow to the intermediate heat exchanger when a reverse cycle defrosting operation is performed to defrost the heat source-side heat exchanger by switching the switching mechanism to the cooling operation state.   
     
     
         2 . The refrigeration apparatus according to  claim 1 , further comprising
 a second-stage injection tube arranged and configured to branch off the refrigerant, which has radiated heat in the heat source-side heat exchanger or the usage-side heat exchanger, and to return the refrigerant to the second-stage compression element,   the second-stage injection tube being arranged and configured to return to the second-stage compression element the refrigerant fed from the heat source-side heat exchanger to the usage-side heat exchanger when the reverse cycle defrosting operation is performed.   
     
     
         3 . The refrigeration apparatus according to  claim 1 , wherein
 the refrigerant that operates in the supercritical range is carbon dioxide.   
     
     
         4 . The refrigeration apparatus according to  claim 2 , wherein the refrigerant that operates in the supercritical range is carbon dioxide.