Refrigeration cycle apparatus

Abstract

A refrigeration cycle apparatus 100 is provided with a working fluid circuit 106 and a first bypass passage 112 . The working fluid circuit 106 is formed of a first compressor 101 , a heat radiator 102 , an expander 103 , an evaporator 104 , a second compressor 105 , and flow passages 106 a to 106 e connecting these components in this order. The expander 103 and the second compressor 105 are coupled to each other by a power-recovery shaft 107 so that the second compressor 105 is driven by the power recovered by the expander 103 . The first bypass passage 112 communicates between a portion from the discharge port of the first compressor 101 to the suction port of the expander 103 in the working fluid circuit 106 and a portion from the outlet of the evaporator 104 to the suction port of the second compressor 105 in the working fluid circuit 106 , at the time of activation of the refrigeration cycle apparatus 100.

1 . A refrigeration cycle apparatus comprising:
 a working fluid circuit formed of a first compressor for compressing a working fluid, a heat radiator for cooling the working fluid compressed by the first compressor, an expander for expanding the working fluid cooled by the heat radiator and recovering power from the working fluid, an evaporator for evaporating the working fluid expanded by the expander, a second compressor for increasing the pressure of the working fluid evaporated by the evaporator and supplying it to the first compressor, and flow passages connecting these components in this order;   a power-recovery shaft coupling the expander to the second compressor so that the second compressor is driven by the power recovered by the expander;   a first bypass passage for communicating between a portion from a discharge port of the first compressor to a suction port of the expander in the working fluid circuit and a portion from an outlet of the evaporator to a suction port of the second compressor in the working fluid circuit; and   a first bypass valve for controlling flow of the working fluid in the first bypass passage, the first bypass valve being provided on the first bypass passage.   
     
     
         2 . The refrigeration cycle apparatus according to  claim 1 , further comprising:
 an activation assist valve provided on the working fluid circuit at a point that is located between the outlet of the evaporator and the suction port of the second compressor and that is closer to the evaporator than a downstream end of the first bypass passage is.   
     
     
         3 . The refrigeration cycle apparatus according to  claim 2 , wherein
 the first bypass valve is provided in an upstream end section or a downstream end section of the first bypass passage.   
     
     
         4 . The refrigeration cycle apparatus according to  claim 2 , wherein
 the first bypass valve is an on-off valve or a three-way valve.   
     
     
         5 . The refrigeration cycle apparatus according to  claim 1 , further comprising:
 a second bypass passage for communicating between a portion from a discharge port of the expander to a downstream end of the first bypass passage in the working fluid circuit and a portion from a discharge port of the second compressor to a suction port of the first compressor in the working fluid circuit.   
     
     
         6 . The refrigeration cycle apparatus according to  claim 5 , further comprising:
 a second bypass valve for controlling flow of the working fluid in the second bypass passage, the second bypass valve being provided on the second bypass passage.   
     
     
         7 . The refrigeration cycle apparatus according to  claim 2 , wherein
 the first bypass valve is opened before activation of the first compressor or in response to the activation of the first compressor.   
     
     
         8 . The refrigeration cycle apparatus according to  claim 2 , wherein
 the first bypass valve is closed after activation of the second compressor.   
     
     
         9 . The refrigeration cycle apparatus according to  claim 8 , further comprising:
 an activation detector for detecting the activation of the second compressor; and   a controller for controlling opening and closing of the first bypass valve, wherein   the controller detects the activation of the second compressor by receiving a detection signal from the activation detector, and closes the first bypass valve.   
     
     
         10 . The refrigeration cycle apparatus according to  claim 9 , wherein
 the activation detector is a temperature detector for detecting a difference between a temperature of the working fluid to be drawn into the expander and a temperature of the working fluid discharged from the expander, and   the activation of the second compressor is detected when the temperature difference exceeds a specific value.   
     
     
         11 . The refrigeration cycle apparatus according to  claim 9 , wherein
 the activation detector is a pressure detector for detecting a difference between a pressure of the working fluid to be drawn into the expander and a pressure of the working fluid discharged from the expander, and   the activation of the second compressor is detected when the pressure difference exceeds a specific value.   
     
     
         12 . The refrigeration cycle apparatus according to  claim 9 , wherein
 the activation detector is a timer for measuring time elapsed from a time point of activation of the first compressor, and   the activation of the second compressor is detected when the time measured by the timer exceeds a specific time.   
     
     
         13 . The refrigeration cycle apparatus according to  claim 2 , wherein
 the activation assist valve is closed before activation of the first compressor, or in response to the activation of the first compressor.   
     
     
         14 . The refrigeration cycle apparatus according to  claim 2 , wherein
 the activation assist valve is opened after activation of the second compressor.   
     
     
         15 . The refrigeration cycle apparatus according to  claim 14 , further comprising:
 an activation detector for detecting the activation of the second compressor; and   a controller for controlling opening and closing of the activation assist valve, wherein   the controller detects the activation of the second compressor by receiving a detection signal from the activation detector, and opens the activation assist valve.   
     
     
         16 . The refrigeration cycle apparatus according to  claim 15 , wherein
 the activation detector is a temperature detector for detecting a difference between a temperature of the working fluid to be drawn into the expander and a temperature of the working fluid discharged from the expander, and   the activation of the second compressor is detected when the temperature difference exceeds a specific value.   
     
     
         17 . The refrigeration cycle apparatus according to  claim 15 , wherein
 the activation detector is a pressure detector for detecting a difference between a pressure of the working fluid to be drawn into the expander and a pressure of the working fluid discharged from the expander, and   the activation of the second compressor is detected when the pressure difference exceeds a specific value.   
     
     
         18 . The refrigeration cycle apparatus according to  claim 15 , wherein
 the activation detector is a timer for measuring time elapsed from a time point of activation of the first compressor, and   the activation of the second compressor is detected when the time measured by the timer exceeds a specific time.   
     
     
         19 . The refrigeration cycle apparatus according to  claim 1 , wherein
 the expander and the second compressor are accommodated in a single closed casing.   
     
     
         20 . The refrigeration cycle apparatus according to  claim 1 , wherein the first bypass valve is a three-way valve provided at a junction of the downstream end of the first bypass passage and the portion from the outlet of the evaporator to the suction port of the second compressor in the working fluid circuit.