Cryogenic refrigeration method and apparatus operating on an expansible fluid

Claim 1

A CRYOGENIC REFRIGERATION APPARATUS IN WHICH A MOVABLE MEMBER DEFINES WITHIN AN ENCLOSURE AT LEAST ONE CHAMBER OF VARIABLE VOLUME AND IN WHICH A HIGH-PRESSURE EXPANSIBLE FLUID IS INTRODUCED THROUGH A FLUID FLOW PATH, INCORPORATING AT LEAST ONE HEAT STORAGE MEANS, INTO SAID CHAMBER AND IS SUBSEQUENTLY EXPANDED AND THEN DISCHARGED THROUGH SAID FLUID FLOW PATH TO A LOW-PRESSURE RESERVOIR, CHARACTERIZED BY HAVING A JOULE-THOMSON LOOP ASSOCIATED WITH SAID CHAMBER, SAID JOULE-THOMSON LOOP COMPRISING (A) A HIGH-PRESSURE BALLAST IN FLUID COMMUNICATION WITH SAID FLUID CHAMBER AND ADAPTED PERIODICALLY TO RECEIVE COLD HIGH-PRESSURE FLUID FROM SAID CHAMBER, (B) AN EXPANSION VALVE ADAPTED TO EXPAND TO FURTHER COOL SAID HIGH-PRESSURE FLUID DELIVERED THERETO FROM SAID HIGH-PRESSURE BALLAST AT AN ESSENTIALLY CONSTANT RATE, (C) A HEAT EXCHANGER ADAPTED TO EFFECT OUT-OF-CONTACT HEAT EXCHANGE BETWEEN SAID COLD HIGH-PRESSURE FLUID ENTERING SAID EXPANSION VALVE AND THE EXPANDED AND FURTHER COOLED FLUID RESULTING FROM PASSAGE THROUGH SAID EXPANSION VALVE; AND (D) MEANS FOR RETURNING SAID EXPANDED AND FURTHER COOLED FLUID IN HEAT EXCHANGE RELATIONSHIP WITH SAID HEAT STORAGE MEANS TO SAID LOW-PRESSURE RESERVOIR OVER AT LEAST THAT PERIOD OF TIME CORRESPONDING TO THAT PART OF EACH REFRIGERATION CYCLE WHEN SAID FLUID IS BEING EXPANDED AND DISCHARGED TO SAID LOW-PRESSURE RESERVOIR.