Thermoacoustic Refrigerator For Cryogenic Freezing

Abstract

A refrigeration system includes a cooler or freezer enclosure; a heat exchanger within the enclosure; a bulk storage tank in fluid communication with the heat exchanger; a sound generator in fluid communication with the heat exchanger; a thermoacoustic refrigerator in acoustic communication with the sound generator; and an indirect heat exchange loop in heat transfer contact with the thermoacoustic refrigerator. The heat exchanger is adapted to receive pressurized fluid from the bulk storage tank, and to provide pressurized gas to the sound generator.

1 . A process for at least one of cooling or freezing comprising:
 providing liquid refrigerant or cryogen at a pressure greater than one atmosphere;   feeding the pressurized liquid refrigerant or cryogen to a cooler or freezer comprising at least a first heat exchanger;   extracting cooling from the pressurized liquid refrigerant or cryogen and vaporizing the liquid refrigerant or cryogen to form a pressurized gas;   passing the pressurized gas through a sound generator and generating sound waves;   applying the sound waves to a thermoacoustic refrigerator; and   generating additional refrigeration from said applying the sound waves to the thermoacoustic refrigerator.   
   
   
       2 . The process of  claim 1 , further comprising delivering gas exiting the sound generator to a cooling section of the cooler or freezer. 
   
   
       3 . The process of  claim 1 , further comprising applying the additional refrigeration to an independent refrigeration loop. 
   
   
       4 . The process of  claim 1 , further comprising applying the additional refrigeration to the cooler or freezer. 
   
   
       5 . The process of  claim 1 , wherein said applying the sound waves comprises propagating the sound waves in a resonator; creating a standing wave in a stack of the thermoacoustic refrigerator; and inducing a temperature gradient across the stack. 
   
   
       6 . The process of  claim 5 , further comprising transferring heat from a warm end of the stack to an external atmosphere and transferring the additional refrigeration into the freezer by an indirect heat exchange loop. 
   
   
       7 . The process of  claim 1 , wherein the liquid refrigerant or cryogen is provided from a bulk storage tank. 
   
   
       8 . The process of  claim 7 , wherein the pressure of the liquid refrigerant or cryogen in the bulk storage tank is up to 6 bar. 
   
   
       9 . The process of  claim 1 , wherein the refrigerant or cryogen is at least one of nitrogen or carbon dioxide. 
   
   
       10 . A process for at least one of cooling or freezing comprising:
 providing liquid refrigerant or cryogen at a pressure greater than one atmosphere;   separating the liquid refrigerant or cryogen into a first liquid stream and a second liquid stream;   vaporizing the first liquid stream to form a pressurized gas stream;   feeding the pressurized gas stream to a cooler or freezer comprising at least a first heat exchanger;   passing the pressurized gas stream through a sound generator and generating sound waves;   applying the sound waves to a thermoacoustic refrigerator;   generating additional refrigeration from said applying the sound waves to the thermoacoustic refrigerator to sub-cool the second liquid stream; and   releasing the sub-cooled second liquid stream into the cooler or freezer.   
   
   
       11 . The process of  claim 10 , wherein said applying the sound waves comprises propagating the sound waves in a resonator, creating a standing wave in a stack of the thermoacoustic refrigerator and inducing a temperature gradient across the stack;
 transferring heat from a warm end of the stack to effect said vaporizing of the first liquid stream; and   transferring the additional refrigeration from a cold end of the stack for sub-cooling the second liquid stream by an indirect heat exchange loop.   
   
   
       12 . The process of  claim 10 , wherein the sub-cooled second liquid stream is released as a spray to contact products in the cooler or freezer. 
   
   
       13 . The process of  claim 10 , wherein the refrigerant or cryogen is at least one of nitrogen or carbon dioxide. 
   
   
       14 . A refrigeration system comprising:
 an enclosure;   at least one heat exchanger within the enclosure;   a bulk storage tank in fluid communication with the at least one heat exchanger;   a sound generator in fluid communication with the at least one heat exchanger;   a thermoacoustic refrigerator in acoustic communication with the sound generator; and   an indirect heat exchange loop in heat transfer contact with the thermoacoustic refrigerator.   
   
   
       15 . The refrigeration system of  claim 14 , wherein the at least one heat exchanger is adapted to receive pressurized fluid from the bulk storage tank, and to provide pressurized gas to the sound generator. 
   
   
       16 . The refrigeration system of  claim 14 , wherein the indirect heat exchange loop is in heat transfer contact with a cold end of a stack of the thermoacoustic refrigerator, and is in heat transfer communication with a second heat exchanger located within the enclosure. 
   
   
       17 . The refrigeration system of  claim 14 , wherein the sound generator further comprises an exit for the pressurized gas to be introduced into the enclosure. 
   
   
       18 . The refrigeration system of  claim 14 , further comprising a conduit separating into a first fluid pathway connecting the bulk storage tank with the at least one heat exchanger, and a second fluid pathway in communication with an interior of the enclosure. 
   
   
       19 . The refrigeration system of  claim 18 , wherein the first fluid pathway is in heat transfer contact with a warm end of a stack of the thermoacoustic refrigerator. 
   
   
       20 . The refrigeration system of  claim 18 , wherein the indirect heat exchange loop is in heat transfer contact with a cold end of a stack of the thermoacoustic refrigerator, and is in heat transfer contact with the second fluid pathway. 
   
   
       21 . The refrigeration system of  claim 18 , further comprising a liquid nitrogen delivery device disposed within the enclosure and in fluid communication with the second fluid pathway. 
   
   
       22 . The refrigeration system of  claim 14 , wherein the bulk storage tank is constructed and arranged to contain a fluid which is at least one of gaseous nitrogen, liquid nitrogen, gaseous carbon dioxide, or liquid carbon dioxide. 
   
   
       23 . A process for at least one of cooling or freezing in the refrigeration system of  claim 14 , comprising:
 delivering a pressurized refrigerant or cryogen fluid from the bulk storage tank to the at least one heat exchanger;   delivering a pressurized gas exiting the at least one heat exchanger to the sound generator and generating sound waves;   applying the sound waves to a thermoacoustic refrigerator; and   generating additional refrigeration from said applying the sound waves to the thermoacoustic refrigerator.   
   
   
       24 . The process of  claim 23 , wherein the pressurized refrigerant or cryogen fluid is a pressurized refrigerant or cryogen gas.