Boiling heat transfer inside parallel microchannels

Heat transfer study was carried out on convective boiling of R134a through nine horizontally positioned, parallel microchannels. The microchannels were of circular cross sections with internal diameter and length of 0.77 mm and 150 mm, respectively. The test conditions are as follows: mass velocity, G, of 250, 500, 750 and 1000 kg/m2s; inlet pressure, pin, of 600, 700, and 900 kPa and subcooling degrees of 1, 10 and 20oC. The experimental results for heat transfer coefficient are compared with seven correlations and semi-empirical models and the best predictions are obtained with the models of Sun and Mishima [13] and Thome et al. [15] for which the Mean Absolute Error was 14.4% and 14.9%, respectively.Papers presented to the 12th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Costa de Sol, Spain on 11-13 July 2016