Experimental Investigation on Pool Boiling Heat Transfer Performance of Superhydrophilic, Hydrophilic and Hydrophobic Surface

Abstract

The recent advances in the growth of heat dissipation from microelectronic devices have led to the two-phase heat transfer method via nucleate boiling for better thermal management. In this study, the effect of surface wettability on the saturated pool boiling heat transfer performance is examined with deionized water. Three types of wettability surfaces are compared, i.e., superhydrophilic (SHPi), hydrophilic (HPi) and hydrophobic (HPo) surfaces. The SHPi surface is prepared by anodic oxidation of the copper surface, while the HPi and HPo surface is prepared by coating Cu–TiO₂ and Cu–MWCNTs, respectively, on the copper surface using the electrochemical deposition method. The earliest incipience of nucleate boiling was observed with the HPo surface, while a most delayed onset of nucleation was obtained for the SHPi surface. The critical heat flux is found to be 1012 kW·m⁻², 1251 kW·m⁻², 1490 kW·m⁻² and 1610 kW·m⁻² corresponding to the plane copper, HPo, HPi and SHPi surfaces following the ascending order. The improved rewetting of the arid area underneath the formed vapour bubble caused a delay in the dry-out occurrence and resulted in a maximum critical heat flux for the SHPi surface. The maximum heat transfer coefficient of 88.42 kW·m⁻²·K⁻¹, 64.7 kW·m⁻²·K⁻¹ and 59.19 kW·m⁻²·K⁻¹ have been observed for the HPi, HPo and SHPi surfaces, respectively, which translates to an increment of 60.2 %, 17.23 % and 7.25 %, respectively, as compared to plain surface. The SHPi surface induces the rightward shifting of the boiling curve as compared to the plane surface, which gives a lower heat transfer coefficient for a particular heat flux.