Air cycle refrigeration capacity control system

Abstract

The present invention describes a method and apparatus for controlling the operating pressure of a Reverse Brayton type refrigeration device 70 for the purposes of regulating cooling capacity and coolant inventory control.

1 . A method for controlling the operating pressure of a refrigeration system, the method comprising:
 a) passing a cryogen through a closed loop Reverse Brayton refrigerator;   b) passing the cryogen through a condensation vessel; and   c) passing the cryogen through a refrigerated space.   
   
   
       2 . The method of  claim 1 , wherein the closed loop Reverse Brayton refrigerator comprises a compressor, a chiller, a heat exchanger and a turbine. 
   
   
       3 . The method of  claim 1 , wherein the condensation vessel comprises a condensation coil. 
   
   
       4 . The method of  claim 3 , wherein the condensation coil is capable of condensing a cryogen. 
   
   
       5 . The method of  claim 4 , wherein the cryogen is a gas selected from the group consisting of air; nitrogen; oxygen-nitrogen mixtures; argon; helium;
 and any combination of the air, nitrogen and oxygen-nitrogen mixtures, argon and helium.   
   
   
       6 . The method of  claim 4 , wherein the cryogen is nitrogen. 
   
   
       7 . The method of  claim 3 , wherein the cryogen that passes through the condensation coil is passed to vent. 
   
   
       8 . A method for controlling the operating pressure of a refrigeration system, the method comprising
 a) passing a cryogen through a condensation vessel to form a gaseous cryogen to vent and a condensate to pass to a refrigerated space;   b) passing the condensate from step a) through a heating element in a refrigerated space, and then passing the resulting heated condensate to a heat exchanger in a Reverse Brayton refrigerator;   c) passing the heated condensate from step b) to a compressor in the Reverse Brayton refrigerator;   d) passing the heated condensate from step c) to a chiller to form a cooled condensate;   e) passing the cooled condensate from step d) to the heat exchanger in opposite flow from the flow in step b);   f) passing the cooled condensate from step e) through a turbine to form a used condensate; and   g) passing the used condensate from step f), which splits into a condensate for passing through the condensation vessel, and a condensate for joining the condensate from step a) into the heating element in the refrigerated space.   
   
   
       9 . A method for controlling the operating pressure of a refrigeration system, the method comprising:
 a) passing a gaseous first cryogen through a condensation vessel;   cooling the gaseous first cryogen to condense some of said first cryogen into a liquid first cryogen and to establish a first pressure within said condensation vessel;   passing any remaining gaseous first cryogen to a vent; and   passing said liquid first cryogen to a refrigerated space;   b) passing the first cryogen from step a) through a heating element in the refrigerated space;
 heating the first cryogen; and 
   passing the first cryogen to a regenerative heat exchanger within a reverse Brayton refrigerator, wherein said regenerative heat exchanger uses heated cryogen and chilled cryogen from the same reverse Brayton refrigerator for fluids which exchange heat therein;   c) passing the first cryogen from step b) to a compressor within the reverse Brayton refrigerator;   d) passing the first cryogen from step c) to a chiller;
 chilling said first cryogen; 
   e) passing the first cryogen from step d) to the regenerative heat exchanger;   f) passing the first cryogen from step e) through a turbine; and   g) passing a first fraction of the first cryogen from step f) to the refrigerated space, and passing a second fraction of the first cryogen from step f) to the condensation vessel.   
   
   
       10 . The method for controlling the operating pressure of a refrigeration system of  claim 9 , wherein said vent is an output to the external atmosphere. 
   
   
       11 . The method for controlling the operating pressure of a refrigeration system of  claim 9 , wherein said vent outputs to a buffer vessel capable of returning vented material to the system. 
   
   
       12 . The method for controlling the operating pressure of a refrigeration system of  claim 9 , wherein said cryogen is a gas selected from the group consisting of air; nitrogen; mixtures of oxygen and nitrogen; argon, helium; and combinations thereof. 
   
   
       13 . The method for controlling the operating pressure of a refrigeration system of  claim 9 , wherein said cryogen consists essentially of nitrogen. 
   
   
       14 . The method for controlling the operating pressure of a refrigeration system of  claim 9 , wherein said first pressure within said condensation vessel is adjusted to provide the cooling demand required.