Experimental investigation on pool boiling heat transfer enhancement using reticular bi-conductive surfaces

Pool boiling has been a research focus over the decades because of its superior heat dissipation performance. This paper provides insights into the underlying pool boiling enhancement mechanism of bi-conductive surface which is an effective modification approach. In this study, a new type of bi-conductive surface is created by embedding a reticular structure made of low-conductive epoxy into a high-conductive copper substrate. Because of the enormous difference in conductivity, the heat flux almost exclusively flows through copper. The existence of epoxy creates periodic spatial surface temperature variations and induces ordered liquid and vapor paths. The influence of the width and depth of epoxy on pool boiling is studied by conducting heat transfer experiments. According to the results, all bi-conductive surfaces exhibit critical heat flux (CHF) increases in copper zone and the improvement is more significant with the increase of epoxy width. However, the depth of the epoxy has no significant effect on pool boiling. At low superheat, the heat transfer coefficient (HTC) in copper zone is relevant to the thermal flow rate of the independent copper zone. At high superheat, bi-conductive surfaces with wider epoxy have higher HTC in copper zone. The results show that for the bi-conductive surface with 0.75 mm width of epoxy, replacing 44% of the high-conductive copper with low-conductive epoxy results in a 270% CHF increase in copper zone and a 108% increase in the maximum total effective thermal power.