Refrigeration device

Abstract

A refrigeration device includes a compression mechanism, a radiator, a first expansion mechanism, a liquid receiver, a second expansion mechanism, an evaporator and a control unit. The control unit minimizes the degree of pressure reduction by the first expansion mechanism when the refrigerant that flows from the refrigerant discharge side of the compression mechanism to the refrigerant inflow side of the first expansion mechanism has reached a subcritical state.

1 . A refrigeration device comprising:
 a compression mechanism configured to compress a refrigerant;   a radiator connected to a refrigerant discharge side of said compression mechanism;   a first expansion mechanism connected to an exit side of said radiator;   a liquid receiver connected to a refrigerant outflow side of said first expansion mechanism;   a second expansion mechanism connected to an exit side of said liquid receiver;   an evaporator connected to a refrigerant outflow side of said second expansion mechanism and to a refrigerant intake side of said compression mechanism; and   a control unit configured to minimize a degree of pressure reduction by said first expansion mechanism when refrigerant flowing from the refrigerant discharge side of said compression mechanism to a refrigerant inflow side of said first expansion mechanism has undergone a transition from a supercritical state to a subcritical state.   
   
   
       2 . The refrigeration device according to  claim 1 , wherein
 said first expansion mechanism is a first expansion valve; and   said control unit is configured to fully open said first expansion valve when refrigerant flowing from the refrigerant discharge side of said compression mechanism to the refrigerant inflow side of said first expansion mechanism has undergone the transition from the supercritical state to the subcritical state.   
   
   
       3 . The refrigeration device according to  claim 1 , further comprising:
 a pressure detector arranged to detect a refrigerant pressure between the refrigerant discharge side of said compression mechanism and the refrigerant inflow side of said first expansion mechanism; wherein   said control unit is configured to minimize the degree of pressure reduction by said first expansion mechanism when the refrigerant pressure detected by said pressure detector is equal to or less than a predetermined pressure.   
   
   
       4 . The refrigeration device according to  claim 3 , wherein
 said first expansion mechanism is a first expansion valve; and   said control unit is configured to fully open said first expansion valve when the refrigerant pressure detected by said pressure detector is equal to or less than the predetermined pressure.   
   
   
       5 . The refrigeration device according to  claim 1 , further comprising:
 a first temperature detector arranged to detect a refrigerant temperature in a first specific region of said radiator; and   a second temperature detector arranged to detect a refrigerant temperature in said first specific region of said radiator; wherein   said control unit is configured to minimize the degree of pressure reduction by said first expansion mechanism when a difference between the refrigerant temperature detected by said first temperature detector and the refrigerant temperature detected by said second temperature detector is equal to or less than a predetermined threshold value.   
   
   
       6 . The refrigeration device according to  claim 5 , wherein
 said first expansion mechanism is a first expansion valve; and   said control unit unit is configured to fully open said first expansion valve when the difference between the refrigerant temperature detected by said first temperature detector and the refrigerant temperature detected by said second temperature detector is equal to or less than the predetermined threshold value.   
   
   
       7 . The refrigeration device according to  claim 1 , further comprising:
 a temperature detector arranged to detect a refrigerant temperature in a specific region of said radiator; wherein   said control unit is configured to minimize the degree of pressure reduction by said first expansion mechanism when the refrigerant temperature detected by said temperature detector is equal to or less than a critical temperature of said refrigerant.   
   
   
       8 . The refrigeration device according to  claim 7 , wherein
 said first expansion mechanism is a first expansion valve; and   said control unit is configured to fully open said first expansion valve when the refrigerant temperature detected by said temperature detector is equal to or less than the critical temperature of said refrigerant.