Refrigerant Charge Storage

Abstract

A refrigeration system includes a compressor, first and second heat exchangers, and an expansion device. A refrigerant recirculating flowpath extends sequentially downstream through the compressor, first heat exchanger, expansion device, and second heat exchanger The system includes a charge storage system. The charge storage system includes first and second refrigerant storage chambers. At least one valve is coupled to the storage chambers to permit the storage chambers to each be individually placed in alternative communication with the flowpath upstream and downstream of the expansion device.

1 . A refrigeration system ( 20 ) comprising:
 a compressor ( 22 );   a first heat exchanger ( 24 );   an expansion device ( 26 ); and   a second heat exchanger ( 28 ), a refrigerant recirculating flowpath ( 40 ) extending sequentially downstream through the compressor, first heat exchanger, expansion device, and second heat exchanger,   
     characterized by:
 a first refrigerant storage chamber ( 85 ); 
 a second refrigerant storage chamber ( 86 ), and 
 at least one valve ( 90 ,  91 ,  96 ,  97 ) coupled to the first refrigerant storage chamber and second refrigerant storage chamber to permit the first and second refrigerant storage chambers to each be individually placed in alternative communication with the flowpath upstream and downstream of the expansion device. 
 
   
   
       2 . The system of  claim 1  wherein:
 the second refrigerant storage chamber is larger than the first refrigerant storage chamber.   
   
   
       3 . The system of  claim 2  further comprising:
 a third refrigerant storage chamber ( 87 ), larger than the second refrigerant storage chamber.   
   
   
       4 . The system of  claim 1  further comprising:
 a third refrigerant storage chamber ( 87 ).   
   
   
       5 . The system of  claim 1  wherein:
 there are no additional refrigerant storage chambers.   
   
   
       6 . The system of  claim 1  further comprising:
 a control system ( 66 ) coupled to the at least one valve and configured to:   select a charge storage condition from a plurality of pre-determined conditions; and   operate the at least one valve to place the system in the selected charge storage condition.   
   
   
       7 . The system of  claim 1  further comprising:
 a transport container ( 224 ) having a compartment ( 226 ) positioned in thermal communication with the second heat exchanger.   
   
   
       8 . The system of  claim 7  further comprising:
 an internal combustion engine-powered generator ( 230 ,  232 ) coupled to the compressor to power the compressor.   
   
   
       9 . The system of  claim 1  wherein:
 a refrigerant charge of the system is at least 50% carbon dioxide by weight.   
   
   
       10 . A refrigeration system ( 20 ) comprising:
 a compressor ( 22 );   a first heat exchanger ( 24 );   an expansion device ( 26 );   a second heat exchanger ( 28 ), a refrigerant recirculating flowpath ( 40 ) extending sequentially downstream through the compressor, first heat exchanger, expansion device, and second heat exchanger; and   means ( 90 ,  91 ,  92 ,  96 ,  97 ,  98 ) for selectively diverting refrigerant from the flowpath to a plurality of chambers ( 85 ,  86 ,  87 ) and returning the refrigerant to the flowpath while maintaining the chambers at pressure below a peak pressure of the flowpath   
   
   
       11 . The system of  claim 10  wherein:
 a refrigerant charge of the system is at least 50% carbon dioxide by weight.   
   
   
       12 . The system of  claim 10  further comprising:
 a transport container ( 224 ) having a compartment ( 226 ) positioned in thermal communication with the second heat exchanger.   
   
   
       13 . A refrigeration system operating method comprising:
 compressing a refrigerant;   passing the compressed refrigerant through a first heat exchanger ( 24 ) downstream of a compressor ( 22 ) along a refrigerant flowpath ( 40 );   expanding the refrigerant downstream of the first heat exchanger along the refrigerant flowpath;   passing the expanded refrigerant through a second heat exchanger ( 26 );   returning the refrigerant to the compressor; and   diverting refrigerant to a storage unit ( 80 ) and returning the refrigerant from the storage system,   
     characterized in that:
 the storage unit has a plurality of chambers ( 85 ,  86 ,  87 ); 
 the storage unit includes at least one valve ( 90 ,  91 ,  92 ,  96 ,  97 ,  98 ) positioned to selectively place each chamber in communication with the flowpath; and 
 the diverting and returning comprises actuating the at least one valve to place each of the chambers in communication with the flowpath either upstream of or downstream of the expansion device. 
 
   
   
       14 . The method of  claim 13  wherein the diverting and returning comprises:
 determining a desired charge storage condition from a plurality of predetermined conditions; and   actuating the at least one valve to achieve the desired charge storage condition.   
   
   
       15 . The method of  claim 13  wherein:
 the compressed refrigerant is passed through the first heat exchanger in a supercritical condition.   
   
   
       16 . The method of  claim 13  wherein:
 the diverting and returning comprises operating with eight different nominal charge storage configurations.   
   
   
       17 . The method of  claim 13  wherein:
 the diverting and returning comprises operating with four to eight different nominal charge storage configurations.