Pool boiling heat transfer enhancement and bubble visualization on a microporous copper over CuO filmed surface through combination of chemical etching and electrochemical deposition

Abstract

For high heat flux engineering application, a Microporous Copper over CuO Film Surface (MCCFS) is prepared to find out the Critical Heat Flux (CHF) and Boiling Heat Transfer Coefficient (BHTC). The bare Cu surface is modified into MCCFS through a combination of two chemical processes, i.e., chemical etching and electrochemical deposition. Various properties of the MCCFS, like porosity, wettability, and roughness, are also analyzed. The saturated pool boiling experiment is carried out by taking distilled water as the boiling liquid at atmospheric pressure. Results show that the CHF and the BHTC of the MCCFS are improved by 71% and 78%, respectively, than the bare Cu. This improvement is mainly due to the increased roughness and decreased wettability of the MCCFS. A visualization-based quantitative analysis of the bubble during boiling is also done to correlate the enhanced heat transfer from the MCCFS. Bubble characteristics like nucleation site density, bubble departure diameter, and bubble departure frequency are analyzed. The enhanced bubble site density, decreased departure diameter, as well as the enhanced departure frequency of the bubble supported the improvement of heat transfer from the MCCFS. A comparative analysis of the performance of heat transfer from the MCCFS is also presented.