On the influences of low-conductive channels in the pool boiling amendment: Empirical investigation with providing correlation

Abstract

• The effect of low-conductive channels on hydrophilicity was experimentally studied. • HTC was Increased by 174% in the novel case of alternatively filled channels. • Surface temperature distribution of bi-conductive surfaces was investigated. • Increasing boiling surface area was compared with optimizing channel geometry. • An empirical correlation for the heat flux of bi-conductive surfaces was provided. As a new approach for enhancing pool boiling, using surfaces with a dual thermal conductivity has been recently proposed. To scrutiny this method, this paper empirically addresses the effects of low-conductive channels in boiling heat transfer. In this regard, nine copper samples with different channels dimension and filling methods were created by a mixture of epoxy and silica aerogel microparticles. Then pool boiling tests with deionized water, detailed contact angle analysis, and imaging of bubbles with a high-speed camera were performed. The results showed that sample 1-A which had alternatively filled channels, in the initial heat fluxes range of 20 to 40 W/cm 2 , improved the pool boiling heat transfer coefficient by 174% compared to the plain sample. Optimizing the dimensional characteristics of low-conductive channels was revealed to be more influential in enhancing pool boiling than increasing the boiling surface area by creating empty channels. Moreover, for the first time, an experimental correlation for predicting the heat flux of bi-conductive surfaces with different geometrical dimensions of low-conductive channels is presented, with a mean absolute error of 8.96%.