Impact of dimensional characteristics of low-conductive channels on the enhancement of pool boiling: An experimental analysis

Abstract Since pool boiling is widely used in many modern industries, the need to improve it has led to the development of new methods. One of the new methods studied much less so far, is creating bi-conductive surfaces. In our study, in three separate series, the effect of pitch, width, and depth of low-conductive channels are investigated. Copper samples were grooved by wire electrical discharge machining (WEDM) and filled with a mixture of epoxy and hydrophilic silica aerogel. Pool boiling experiments were conducted with deionized water at atmospheric pressure. In addition, the samples' images were obtained by scanning electron microscopy (SEM), and visualization of bubble formation was provided by a high-speed camera. According to the results, sample 4 with 2.5 mm channel pitch, 0.5 mm width, and 0.3 mm depth reached a heat flux of 103.9 W/cm2 and heat transfer coefficient (HTC) of 7.6 W/cm2 K. This shows 62 % and 58 % improvement respectively, compared to the plain surface. Channel pitch best selection resulted in 21 % reduction in bubble departure diameter. Increasing the channel width to an optimal value of 1.5 mm leads to thermal concentration and improving HTC up to 146 % in low heat fluxes. In depth variation series, the lowest value of 0.3 mm led to the best performance in improving heat transfer. The present study provides a good understanding of dimensional characteristics' impact of low-conductive channels on pool boiling heat transfer.