Refrigeration system

Abstract

In a refrigerant circuit ( 20 ), an air conditioning unit ( 12 ), a cold-storage showcase ( 13 ), and a freeze-storage showcase ( 14 ) are connected in parallel to an outdoor unit ( 11 ). When placing an indoor heat exchanger ( 71 ) of the air conditioning unit ( 12 ) in the thermo-off state, a degree-of-opening control means ( 101 ) provides control so that an indoor expansion valve ( 72 ) is placed in the fully closed state. Thereafter, the degree-of-opening control means ( 101 ) detects the accumulated amount of refrigerant within the indoor heat exchanger ( 71 ) and then adjusts the degree of opening of the indoor expansion valve ( 72 ) depending on the refrigerant amount detected.

1 . A refrigeration system including a refrigerant circuit, the refrigerant circuit being configured such that a plurality of utilization side units are connected in parallel to a heat source side unit having a compressor and a heat source side heat exchanger, wherein at least one of the plurality of utilization side units includes a heating heat exchanger capable of a heating operation in which heat is released from refrigerant and an expansion valve associated with the heating heat exchanger,
 the refrigeration system including degree-of-opening control means for performing:   (a) when placing the heating heat exchanger in the out-of-operation state, a first control operation of reducing the degree of opening of the expansion valve to such an extent that the expansion valve is either fully closed or very slightly opened; and   (b) after the completion of the first control operation, a second control operation of adjusting, based on an index indicative of the accumulated amount of refrigerant within the heating heat exchanger, the degree of opening of the expansion valve.   
   
   
       2 . The refrigeration system of  claim 1 , wherein the first control operation of the degree-of-opening control means is an operation to place the expansion valve in the fully closed state. 
   
   
       3 . The refrigeration system of either  claim 1  or  claim 2 , wherein, in the second control operation of the degree-of-opening control means, either the degree of refrigerant subcooling on the inlet side of the heating heat exchanger or the degree of refrigerant subcooling within the heating heat exchanger serves as the index indicative of the accumulated amount of refrigerant within the heating heat exchanger. 
   
   
       4 . The refrigeration system of  claim 3 , wherein, in the second control operation of the degree-of-opening control means, the expansion valve is forcibly opened if the expansion valve remains in the fully closed state for longer than a predetermined length of time. 
   
   
       5 . The refrigeration system of  claim 1 ,
 wherein the utilization side units other than the one that is provided with the heating heat exchanger each include a respective refrigeration heat exchanger capable of a refrigeration operation in which refrigerant absorbs heat from air;   wherein the refrigerant circuit is configured to be capable of a heat recovery operation in which refrigerant delivered out from the compressor dissipates heat in the heating heat exchanger, absorbs heat in the refrigeration heat exchanger, and then is drawn into the compressor; and   wherein there is provided operation control means which provides control so that the heat recovery operation is temporarily carried out if, in the second control operation of the degree-of-opening control means, the index indicative of the accumulated amount of refrigerant within the heating heat exchanger continues to be in excess of a specified value for longer than a predetermined length of time.