Methods for producing low temperature refrigeration

Claim 1

A LOW TEMPERATURE PROCESS FOR REFRIGERATING A DEVICE TO BE COOLED COMPRISING THE STEPS OF COMPRESSING AND EXPANDING A FIRST GAS IN A CLOSED CYCLE IN WHICH THE COMPRESSED FIRST GAS IN A CLOSED CYCLE PLURALITY OF WORK EXPANSION STEPS AT PROGRESSIVELY DECREASING TEMPERATURE LEVELS AND IN WHICH EFFLUENT FROM THE WORK EXPANSION STEPS IS PASSED IN HEAT INTERCHANGE WITH COMPRESSED FIRST GAS TO COOL COMPRESSED FIRST GAS PRIOR TO THE WORK EXPANSION STEP, COMPRESSING A SECOND GAS, PASSING COMPRESSED SECOND GAS SUCCESSIVELY IN HEAT INTERCHANGE WITH EFFLUENT OF THE WORK EXPANSION STEPS AT THE PROGRESSIVELY DECREASING TEMPERATURE LEVELS TO COOL COMPRESSED SECOND GAS TO A LOW TEMPERATURE, EXPANDING IN A VALVE COOL COMPRESSED SECOND GAS TO EFFECT AT LEAST PARTIAL LIQUEFACTION OF THE SECOND GAS, PASSING EXPANDED SECOND GAS IN HEAT INTERCHANGE WITH THE DEVICE TO BE COOLED, AND PASSING SECOND GAS FOLLOWING THE LAST-NAMED HEAT INTERCHANGE IN COUNTERCURRENT HEAT INTERCHANGE WITH COMPRESSED SECOND GAS FOLLOWING THE AFOREMENTIONED HEAT INTERCHANGE BETWEEN COMPRESSED SECOND GAS AND EFFLUENT OF THE WORK EXPANSION STEPS, THE COMPRESSED SECOND GAS BEING PASSED IN HEAT INTERCHANGE WITH EFFLUENT OF THE WORK EXPANSION STEPS PRIOR TO THE HEAT INTERCHANGE BETWEEN THE EFFLUENT OF THE WORK EXPANSION STEPS AND THE COMPRESSED FIRST GAS.