An Experimental Investigation of the Effects of Subcooling and Velocity on Boiling of Freon-113

Abstract

Boiling heat transfer correlations were obtained for the maximum and minimum heat fluxes. Relationships among qmin/qmax, Weber number, and liquid Jakob number were obtained. Compelling evidence was found to indicate that significant cooling of the wake and/or the forward stagnation line can be caused by large-scale liquid–solid contacts while other parts of the surface experienced film boiling with little or no contact in the transition-film boiling regime. A criterion for large-scale liquid-solid contacts was developed. Another purpose of this study was to investigate whether a stable transition of boiling exists, i.e., if the ratio of the minimum and maximum heat fluxes approaches unity as liquid subcooling and velocity are increased. Extensive data using Freon-113 were taken, covering a wide range of fluid velocities (1.5 to 6.9 m/s) and liquid subcooling (29 to 100°C) at pressures ranging from 122 to 509 kPa. Cylindrical electric resistance heaters of two diameters, 6.35 mm and 4.29 mm, and made of Hastelloy-C and titanium, respectively, were used. The maximum qmin/qmax achievable with the apparatus was 0.9.