Nucleate boiling heat transfer of R134a on enhanced tubes

The present paper reports the results of an experimental investigation on saturated pool boiling heat transfer of R134a on High-Flux, Gewa-B, Turbo-CSL and Turbo-BII HP tubes. Experiments have been carried out at saturation temperatures of 5, 10 and 20 degrees C and heat fluxes from 20 to 70 kW/m(2). At most of the experimental conditions tested, an almost negligible effect of the saturation temperature on the heat transfer coefficient was found. Except for Turbo-CSL, the heat transfer coefficient presented either a slight decrease in its value or an almost constant value with increasing heat flux. The heat transfer enhancement ratios of the High-Flux, Gewa-B, Turbo-CSL and Turbo-BII HP tubes were 4.9-21.3, 2.4-5.2, 2.4-2.9 and 1.8-7.0, respectively, compared to a plain tube. (C) 2005 Elsevier Ltd. All rights reserved.