Cryostat refrigeration system using mixed refrigerants in a closed vapor compression cycle having a fixed flow restrictor

摘要

A closed cycle cryogenic refrigerating system with a fixed restrictor operates with a compressor inlet pressure in a range of 0.1 Mpa to 0.4 Mpa and compressor discharge pressure in a range of 1.5 Mpa and 2.5 Mpa. A basic cryogenic refrigerant mixture is used to which is added approximately 3% to 25% of helium, hydrogen and/or neon. A ratio of refrigerant density at the inlet of the fixed restrictor between steady-state operation and operation at the beginning of cool-down is in an approximate range of 7 to 17. Relatively rapid cool-down is achieved and evaporator temperature is maintained in an approximate range of 70K to 120K.