Helium Refrigerators for Operation in the 10°–30°K Range
The improved postlaunch reliability of important components and systems in the space program is due, in part, to increased emphasis on check-out and performance tests under simulated space conditions. The size of chambers used for these tests has continued to increase to accommodate the larger vehicles. It has been possible to provide and sustain high vacuums in these large chambers, even with high gas loads, by the use of cryopumping together with conventional mechanical and oil-diffusion-type vacuum pumps. The refrigeration for cryopumplng has been supplied with dense-gas helium refrigerators. These refrigerators, usually operating below 20°K, range in capacity from a few watts to several kilowatts. Refrigeration cycles of this type have been previously described by various authors [1–3]. This, paper presents an analysis of the thermodynamic cycle usually employed and a description of the components, operation, and performance of a 1-kw unit.
KeywordsHeat Exchanger Pressure Ratio Refrigeration Cycle Compressor Inlet Cryogenic Engineer
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