Effects of electric field on pool boiling heat transfer over composite microstructured surfaces with microcavities on micro-pin-fins

Abstract

In this study, we proposed to achieve synergistically enhanced pool boiling performance by combining the effects of an electric field and composite microstructures. To test the proposed strategy, the pool boiling heat transfer performances of four kinds of microstructured surfaces, including a micro-pin-fined surface (PF-30–60) and three kinds of composite microstructured surfaces with different numbers of microcavities at the top of each micro-pin-fin, were investigated in HFE-7100 under an electric field. The experimental results show that the bubbles on the composite microstructured surfaces are preferential to generate at the top of the micro-pin-fins, which not only effectively reduces the wall superheats at the onset of nucleate boiling on the composite microstructured surfaces, but also prevents a large number of bubbles from generating at the roots of the micro-pin-fins, and thus effectively alleviates the deterioration of boiling heat transfer caused by the field trap effect. Such a trend becomes more obvious with the increase in the number of microcavities. The CHF of the composite microstructured surface can be improved by 50%∼100% by the electric field, but it can only be enhanced by 26%∼78% on PF-30–60. Compared with that of the smooth surface, the CHF of PF-30–60 is increased by 36%∼52%, while the CHF of the composite microstructured surface is increased by 75%∼91% under the electric field.