KUWAHARA Ken Kyushu University, Institute of Advanced Material Study, Research Associare, 機能物質科学研究所, 助手 (90243964)
YU Jian Kyushu University, Institute of Advanced Material Study, Associare Professor, 機能物質科学研究所, 助教授 (30274533)
|Budget Amount *help
¥2,100,000 (Direct Cost : ¥2,100,000)
Fiscal Year 1997 : ¥700,000 (Direct Cost : ¥700,000)
Fiscal Year 1996 : ¥1,400,000 (Direct Cost : ¥1,400,000)
This project deals with the cxperimental and numerical research on the thermal optimization of plate-fin condenser for alternative refrigerant mixtures. Alternative refrigerants HFC134a, HCFCI23 and HFC32 and their mixtures are used as the working fluid. The effect of fin configuration on heat transfer characteristics has been clarified through this project.
In the numericaI study, the laminar, film condensation on a finned vertical surface is analyzed. Thee-dimensional distribution of the condensed liquid fiIm thickness, the prcssure and the radius of liquid film in heat fiux and the Nusselt number along the vertical direction are obtained. From a series of calculation results, the effects of fin horizontal direction, the distributions of averaged height, fin pich, fin thickness and the radius of concave joint reion of base plate and fin on the liquid film shape are shown, and the effects of the fin shape parameters on heat transfer enhancement ratio are examined. The averged Nusselt number on a vertical finned surface, Nu_m, are correlated by the Bond number Bo, the Galileo number Ga_L, the phase change number Ph, and the averaged Nusselt number Nu_<mo>.
ln the cxperimental study, the condensation of NARMs HFC134a/HCFC123 is carried out for a plate-fin heat cxchanger. The heat transfer characteristics of condensation of pure and mixed refrigerants are compared, and cmpirical correlation equations of the liquid film heat transfer with condensation and the single phase heat transfer of refrigerant and cooling water are obtained. The calculation method to predict the condensation chararacteristics of NARMs is dcveloped using the cmpidcal correlation equations obtained experimentally. It is shown that agreement between cxperiment and prediction is good. The mass transfer characteristics are also revealed.