Investigation of Two Phase Heat Transfer Coefficients of Cryogenic Mixed Refrigerants

Mixed Refrigerant Joule Thomson (MR-JT) refrigerators are widely used in various kinds of cryogenic systems these days. Although heat transfer coefficient estimation for a multiphase and multi-component fluid in cryogenic temperature range is necessarily required in the heat exchanger design of MR-JT refrigerator, it has been rarely discussed so far. In this paper, condensation and evaporation heat transfer coefficients of mixed refrigerant are measured in a microchannel heat exchanger. Printed Circuit Heat Exchanger (PCHE) has been developed as a compact microchannel heat exchanger and used in the experiment. Several two-phase heat transfer coefficient correlations are examined to discuss the experimental measurement results. The result of this paper shows that cryogenic mixed refrigerant heat transfer coefficients can be estimated by conventional two-phase heat transfer coefficient correlations.