流路断面の変更による二相流形蒸発器の最適化に関する検討

概要

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Evaporation heat transfer coefficients depend on the mass flux and quality. When a non-azeo-tropic mixture is used as a working fluid, this dependence is significant due to the suppression of nucleate boiling. It is possible to improve the heat transfer performance if the channel cross-sectional area is enlarged at the latter part of the evaporator, namely, the mass flux is reduced in the high-quality region where the pressure drop is large. This work involves an analytical investigation on the enhancement effect by varying the channel cross section. It was assumed that the working fluid was a mixture of refrigerants R 123 and R 134 a, and that the tubes used were smooth or spirally grooved. As a result, the heat transfer area and the channel volume were reduced by more than 20% when the pressure drop is permissible enough.
一般社団法人日本機械学会の論文
1996-09-25