EXPANDER CYCLES FOR 80 K REFRIGERATION

Cooling of electronic equipment at liquid nitrogen temperatures and prospects of many applications of high temperature superconductivity have renewed the interest in 80 K refrigeration. The thermodynamic efficiency of six different expander cycles are being calculated and compared with each other. A Claude cycle with nitrogen as working fluid and two expanders turns out to be the most efficient cycle. All components of a refrigerator working with this cycle are well developed and have proven their reliability. The system is best suited for the capacity range between 0.5 and 20 kW.