Experimental study on boiling heat transfer and pressure drop characteristics of hybrid jet microchannel heat sink

Abstract

Hybrid jet microchannel cooling can improve the non-uniform temperature distribution, significant pressure drop in microchannel, and the uneven heat transfer coefficient in jet impact. The heat transfer and pressure drop characteristics of a hybrid jet microchannel heat sink were investigated experimentally using deionized water as the working fluid. The experiments were carried out under the operating conditions of mass fluxes from 200 ∼ 600 kg/m2s, subcooling degrees from 20 ∼ 40 K, jet-to-target spacings from 1 ∼ 2.5 mm, and outlet pressure of 1 atm. The results show that increasing jet-to-target spacing and mass flux and decreasing subcooling can improve the heat transfer coefficient, and the maximum heat transfer coefficients increase by 58 %, 73 %, and 50 %, respectively. A heat transfer correlation for the hybrid jet microchannel is proposed with a mean absolute error of 6.5 % based on the experimental data. Since large jet-to-target spacing has more expansion space and is closer to the length of the potential core, increasing jet-to-target spacing results in higher critical heat flux at low mass flux. Compared to the heat sink with higher jet-to-target spacing, the pressure drop of the heat sink with the lower one is significantly affected by the mass flux due to the superposition of size effect of the channel and gas–liquid friction. In addition,the slope that pressure drop curves increase with the decrease of jet-to-target spacing rises with the mass flux, while it is not apparent with the subcooling. As the subcooling and jet-to-target spacing rise and the mass flux decreases, the coefficient of performance will increase.