The use gas mixture cryocoolers can be widely applied in spacecraft under 300-20K. The advantages of such mixtures are three-fold: (1) High reliability, (2) low noise level, and (3) application over the temperature range. Until recently the range we are addressing has been validated only theoretically. The results are based on calculations of gas-mixture properties and counter-flow heat exchangers. We recently have verified the results in laboratory tests. In the present report, we display a theoretical model of this effort. For description of thermal properties of mixtures, we only use of a single function: the dependency of enthalpy on temperature, both for direct and counter flows. In addition, have also created a special method of solutions for non-linear non-correct equations for a counter-flow heat-exchanger thermal-conductivity. We have based our results on a number of laboratory results comparing theoretical values with experimental results for gas-mixture cryocoolers under 300-40K temperature range and have extrapolated these results to 20K.
Space Cryogenics Workshop
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