Refrigeration System

Abstract

A refrigerant circuit ( 10 ) operates in a refrigeration cycle in which the pressure of refrigerant discharged from a compressor ( 22 ) is at or above the critical pressure. In performing an operation in which a first indoor heat exchanger ( 33 a ) performs a heating operation and, concurrently, a second indoor heat exchanger is made inactive, an indoor expansion valve ( 34 b ) associated with the inactive indoor heat exchanger ( 33 b ) is fully closed.

1 . A refrigeration system comprising a refrigerant circuit formed so that a plurality of utilization side circuits including their respective utilization side heat exchangers and electric motor-operated valves associated with the respective utilization side heat exchangers are connected in parallel to a heat-source side circuit including a compressor and a heat-source side heat exchanger, each of the utilization side heat exchangers being capable of individually performing a heating operation to release heat from refrigerant in the utilization side heat exchanger, wherein the refrigerant circuit is configured to operate in a refrigeration cycle in which the pressure of refrigerant discharged from the compressor is at or above the critical pressure. 
   
   
       2 . The refrigeration system of  claim 1 , further comprising a control means that, in performing an operation in which at least one said utilization side heat exchanger in heating operation and at least one said inactive utilization side heat exchanger coexist, fully closes the electric motor-operated valve associated with the at least one inactive utilization side heat exchanger. 
   
   
       3 . The refrigeration system of  claim 2 , wherein when a first specified time t 1  has passed since full closure of the electric motor-operated valve associated with the at least one inactive utilization side heat exchanger, the control means temporarily opens the electric motor-operated valve for a second specified time t 2 . 
   
   
       4 . The refrigeration system of  claim 3 , wherein
 each of the utilization side heat exchangers is placed in a room and configured to release heat from refrigerant to a room air,   room temperature sensors for detecting the temperatures of rooms associated with the respective utilization side heat exchangers are provided around the respective utilization side heat exchangers, and   the refrigeration system further comprises a correction means that corrects one or both of the first specified time t 1  and the second specified time t 2  based on the temperature detected by the room temperature sensor associated with the at least one inactive utilization side heat exchanger.   
   
   
       5 . The refrigeration system of  claim 2 , further comprising refrigerant density detecting devices for detecting the refrigerant densities in the associated utilization side heat exchangers, wherein when the refrigerant density detected by at least one said refrigerant density detecting device associated with the at least one inactive utilization side heat exchanger exceeds a specified refrigerant density after full closure of the electric motor-operated valve associated with the at least one inactive utilization side heat exchanger, the control means temporarily opens the electric motor-operated valve. 
   
   
       6 . The refrigeration system of any one of  claims 1  to  5 , the refrigerant circuit is filled with carbon dioxide as refrigerant. 
   
   
       7 . The refrigeration system of any one of  claims 2  to  5 , further comprising supply openings through which air having passed through the associated utilization side heat exchangers is let out and opening/closing mechanisms for opening and closing the associated supply openings, wherein each of the opening/closing mechanisms is configured to open the supply opening of the associated utilization side heat exchanger when in heating operation and close the supply opening of the associated utilization side heat exchanger when inactive.