Experimental study on the heat transfer coefficient of water flow boiling in mini/microchannels

Abstract

The heat transfer coefficients of the evaporative water flow in mini/microchannels are studied experimentally to explore the novel heat dissipation for high power electronics. Two sets of parallel channels which are 61 channels with hydraulic diameter of 0.293 mm and 20 channels with hydraulic diameter of 1.2 mm are investigated respectively. The inlet and outlet temperatures of fluids, and the temperatures beneath the channels are measured to calculate the heat dissipation of the evaporative water in channels. The experiments are carried out with the mass flow rates range from 11.09 kg/(m 2 s) to 44.36 kg/(m 2 s) for minichannels and 49.59 kg/(m 2 s) to 198.37 kg/(m 2 s) for microchannels. The effective heat flux range from 5 W/cm 2 to 50 W/cm 2, and the resulted outlet vapor qualities range from 0 to 0.8. The relations of the heat transfer coefficient with heat flux and vapor quality are analyzed according to the results. The experimental heat transfer coefficients are compared with the prediction of latest developed correlations. A new correlation takes the effect of Bond number is proposed, and be verified that it is effective to predict the heat transfer coefficient of both minichannels and microchannels in a large range of vapor qualities.