LOCAL EVAPORATION HEAT TRANSFER IN A SMOOTH TUBE AND A MICRO-FIN TUBE USING REFRIGERANTS 22 AND 113.
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A systematic comparison of in-tube evaporation performance was carried out for a smooth tube and a micro-fin tube, representative of current enhancement technology, using Refrigerants 22 and 113 (R-22 and R-113). Commercial refrigeration and airconditioning tubes of 9. 52 mm O. D. were tested by direct electrical heating of the tube walls. For both test fluids, an increase in the mass velocity resulted in a decrease in the enhancement factor (ratio of enhanced tube heat transfer coefficient to coefficient for a smooth tube of the same envelope diameter, at similar flow conditions). In addition, R-22 resulted in lower enhancement factors for the micro-fin tube when compared with R-113. The enhancement factors were 1. 2 to 1. 7 for R-22 and 1. 3 to 2. 2 for R-113.
author list (cited authors)
Khanpara, J. C., Pate, M. B., & Bergles, A. E.