Study on Boiling Heat Transfer Performance and Strengthening Mechanism on Pillar-cavity Composite Microstructured Surfaces
In the present study,the pool boiling heat transfer performance on 9 kinds of pillar-cavity composite microstructured surfaces in HFE-7100 was studied.The experimental results show that the wall superheats at the onset of nucleate boiling points of the pillar-cavity composite microstructured surfaces decreases to about 0 K,which is significantly lower than that of a smooth surface(SS)and the ordinary micro-pillar surface(PF-30-60),and the nucleate boiling heat transfer coefficient(HTC)is significantly higher than that of PF-30-60 and SS.In addition,the growth rate of HTC increased with the increase in the number of microcavities.Bubbles on the pillar-cavity composite microstructured surfaces are mainly generated in the microcavities at the top of the micro-pillar.Therefore,at high heat flux,the bubble blockage in the microchannel can be relieved,and the critical heat flux(CHF)of the microchannel is higher than that of PF-30-60 and SS.The HTC increases with the increase in the height of the micro-pillar(H).However,the CHF increases first and then keeps the same with the increase of H,which indicates that for this kind of surfaces,increasing the height of micro-pillars does not necessarily increase CHF effectively.
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