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ISSN Online: 2377-424X

International Heat Transfer Conference 12
August, 18-23, 2002, Grenoble, France

Pool boiling heat transfer of binary refrigerant mixtures in a confined space

Get access (open in a dialog) DOI: 10.1615/IHTC12.4600
6 pages

Résumé

Pool boiling data for pure R123, pure R141b and four of their mixturesun der atmospheric pressure in a variable gap-size confined space oriented horizontally are reported in this work. This system exhibits negligible mass diffusion effect and offers a good model system for studying confinement effect on boiling of binary mixtures. The experimental results reveal that the heat transfer coefficient of binary mixture for larger gap sizesi sne arly identical to that obtained for unconfined boiling and is comparable with that predicted by conventional boiling correlation for an equivalent pure fluid (EPF), which isan ideal pure substance of exactly the same physical properties with the binary mixture under study. The composition effect, however, becomes more profound as gap size decreases. For a given heat flux, three regimes can be identified as gap size decreased. The decrease of gap size led firstly to a gradual improvement in heat transfer performance until an optimal gap size is reached. At that gap size, the heat transfer coefficient may increase to as much as four times of those measured for unconfined boiling. Further decrease of gap size, however, results in drastical deterioration in heat transfer. After occurrence of the "worst" situation, heat transfer coefficient increases slightly with the further decrease of gap size. All those trends are explained by a phenomenological analysis of boiling in a confined space and boiling of mixtures. Further studieson other HCFC mixturesand HFC mixturesare desirable.