Refrigerating machine and control method thereof

Abstract

A refrigerating machine which is equipped with: a turbocompressor 2 that compresses a refrigerant; a condenser 3 that condenses the refrigerant compressed by the turbocompressor 2; an intermediate cooler 4 that is a plate heat exchanger which performs heat exchange between the liquid refrigerant introduced from the condenser 3 and the two-phase refrigerant obtained by expanding, with a sub-expansion valve 13, part of the liquid refrigerant introduced from the condenser 3; a main expansion valve 5 that expands the liquid refrigerant introduced from the intermediate cooler 4; and an evaporator 7 that evaporates the refrigerant introduced from the main expansion valve 5. The plate heat exchanger includes 80 or more laminated plates, the width of which is 100-400 mm and the height of which is 300-1000 mm.

1 . A refrigerator comprising:
 a compressor which compresses a refrigerant;   a condenser which condenses the refrigerant compressed by the compressor;   an economizer which is a plate type heat exchanger which performs heat exchange between a liquid refrigerant introduced from the condenser and a two-phase refrigerant obtained by expanding a portion of the liquid refrigerant introduced from the condenser by a sub-expansion valve;   a main expansion valve which expands the liquid refrigerant introduced from the economizer; and   an evaporator which evaporates the refrigerant introduced from the main expansion valve, wherein the plate type heat exchanger is configured such that a width of a plate is 100 mm or more and 400 mm or less, a height of the plate is 300 mm or more and 1,000 mm or less, and the number of stacked plates is 80 or more.   
     
     
         2 . A refrigerator comprising:
 a compressor which compresses a refrigerant;   a condenser which condenses the refrigerant compressed by the compressor;   an economizer which is a plate type heat exchanger which performs heat exchange between a liquid refrigerant introduced from the condenser and a two-phase refrigerant obtained by expanding a portion of the liquid refrigerant introduced from the condenser by a sub-expansion valve;   a main expansion valve which expands the liquid refrigerant introduced from the economizer;   an evaporator which evaporates the refrigerant introduced from the main expansion valve;   a bypass path which bypasses the economizer and through which the liquid refrigerant from the condenser is introduced to an upstream side of the main expansion valve;   a bypass valve which is provided in the bypass path; and   a controller which controls an opening degree of the bypass valve.   
     
     
         3 . A refrigerator comprising:
 a compressor which compresses a refrigerant;   a condenser which condenses the refrigerant compressed by the compressor;   an economizer which is a plate type heat exchanger which performs heat exchange between a liquid refrigerant introduced from the condenser and a two-phase refrigerant obtained by expanding a portion of the liquid refrigerant introduced from the condenser by a sub-expansion valve;   a main expansion valve which expands the liquid refrigerant introduced from the economizer;   an evaporator which evaporates the refrigerant introduced from the main expansion valve;   a bypass path which bypasses the economizer and through which the liquid refrigerant from the condenser is introduced to a cooled-medium inlet side of the evaporator;   a bypass valve which is provided in the bypass path; and   a controller which controls an opening degree of the bypass valve.   
     
     
         4 . The refrigerator according to  claim 2 ,
 wherein in a case where a difference between a pressure in the condenser and a pressure in the evaporator is equal or less than a predetermined value or an opening degree of the main expansion valve is equal to or more than a predetermined value, the controller increases the opening degree of the bypass valve.   
     
     
         5 . A control method of a refrigerator,
 the refrigerator includes   a compressor which compresses a refrigerant,   a condenser which condenses the refrigerant compressed by the compressor,   an economizer which is a plate type heat exchanger which performs heat exchange between a liquid refrigerant introduced from the condenser and a two-phase refrigerant obtained by expanding a portion of the liquid refrigerant introduced from the condenser by a sub-expansion valve,   a main expansion valve which expands the liquid refrigerant introduced from the economizer,   an evaporator which evaporates the refrigerant introduced from the main expansion valve,   a bypass path which bypasses the economizer and through which the liquid refrigerant from the condenser is introduced to an upstream side of the main expansion valve, and   a bypass valve which is provided in the bypass path,   the control method comprising:   increasing the opening degree of the bypass valve in a case where a difference between a pressure in the condenser and a pressure in the evaporator is equal or less than a predetermined value or an opening degree of the main expansion valve is equal to or more than a predetermined value.   
     
     
         6 . A control method of a refrigerator,
 the refrigerator includes   a compressor which compresses a refrigerant,   a condenser which condenses the refrigerant compressed by the compressor,   an economizer which is a plate type heat exchanger which performs heat exchange between a liquid refrigerant introduced from the condenser and a two-phase refrigerant obtained by expanding a portion of the liquid refrigerant introduced from the condenser by a sub-expansion valve,   a main expansion valve which expands the liquid refrigerant introduced from the economizer,   an evaporator which evaporates the refrigerant introduced from the main expansion valve,   a bypass path which bypasses the economizer and through which the liquid refrigerant from the condenser is introduced to a cooled-medium inlet side of the evaporator, and   a bypass valve which is provided in the bypass path,   the control method comprising:   increasing the opening degree of the bypass valve in a case where a difference between a pressure in the condenser and a pressure in the evaporator is equal or less than a predetermined value or an opening degree of the main expansion valve is equal to or more than a predetermined value.   
     
     
         7 . The refrigerator according to  claim 3 ,
 wherein in a case where a difference between a pressure in the condenser and a pressure in the evaporator is equal or less than a predetermined value or an opening degree of the main expansion valve is equal to or more than a predetermined value, the controller increases the opening degree of the bypass valve.