Heat flux partitioning analysis of pool boiling on micro structured surface using infrared visualization

Abstract

We study a heat flux partitioning analysis of nucleate pool boiling on microstructured surface through infrared visualization technique. A heat flux partitioning analysis of the nucleate pool boiling consists of three kinds of heat flux mechanisms; convective, quenching and evaporative heat flux. It is importance of understanding the dominance among those heat flux mechanisms to fundamental study of the nucleate boiling heat transfer, but it is not clearly figured out. In this study, directly measuring the boiling parameters; bubble departure size, bubble releasing frequency, nucleation site density and bubble growth time through the infrared visualization technique, a nucleate boiling heat flux portioning analysis on pool boiling has been carried out. The experimental results indicate that sum of the three heat flux partitions from the measured boiling parameters shows good agreement with the experimentally given total heat flux. In addition, the quenching heat flux and evaporative heat flux becomes dominant at high heat flux regime by numerous bubble generation and fast bubble growth. On the microstructured surface, the increased heating surface area by the roughness ratio intactly contributes the heat transfer performance enhancement, and the area increase effect have to be reflected on the heat flux partitioning calculation. Although there are still many arguments of the heat flux portioning model analysis on pool boiling heat transfer from literatures and the methodological limitation due to the chaotic boiling phenomena, this study gives good inspiration and understanding of the boiling heat transfer mechanism and the importance of each heat transfer mechanism. (C) 2016 Elsevier Ltd. All rights reserved.