STUDY ON HEAT TRANSFER CHARACTERISTICS AND STABILITY OF SUBCOOLED FLOW BOILING IN A NOVEL BOTTOM-DIVERGING MICROCHANNEL WITH EQUAL CROSS-SECTIONAL AREA

Abstract

The enhancement of boiling heat transfer and its stability have been widely studied in the field of flow boiling in microchannel heat sinks. In this study, a novel diverging microchannel is proposed to enhance the heat transfer performance and boiling stability during subcooled flow boiling in the microchannel by the channel structure of divergent fluid-solid coupling bottom interface and equal cross-sectional area. Two-phase patterns, heat transfer characteristics, and pressure variations of subcooled flow boiling of HFE-7100 in this microchannel, its reversal flow microchannel, uniform microchannel, and diverging microchannel are compared under different heat flux conditions. The results show that the microchannel structure directly affects the nucleation time of bubbles and their behavior. At the same heat flux, the bubble nucleation time in the bottom-diverging microchannel with equal cross-sectional area is the longest, the bubble size is the smallest and the closest to the exit of the microchannel, which is beneficial to rapidly exhaust of the bubbles. The bottom-diverging microchannel with equal cross-sectional area exhibits higher heat transfer coefficient and smaller pressure fluctuation than its reversal flow microchannel, uniform microchannel, and diverging microchannel.