Effects of super-hydrophilicity and orientation of heater surface on bubble behavior and the critical heat flux in pool boiling

Abstract

This study investigated the boiling heat transfer characteristics of a super-hydrophilic surface with de-ionized water at different orientations. Pool boiling experiments were conducted at inclination angles of 45°, 90°, and 135° by rotating the experimental apparatus. The experimental results were analyzed to investigate the influence of inclination angle and hydrophilicity of the surface on the boiling heat transfer characteristics. Parameters such as the maximum and minimum vapor thicknesses, bubble wavelength, bubble velocity, BHTC (Boiling Heat Transfer Coefficient) and CHF (Critical Heat Flux) were measured during the experiment. An enhancement in the values of the parameters of the bubble dynamics was observed during the boiling experiment using the super-hydrophilic PCB (Printed Circuit Board) heater, indicating improved heat transfer during the experiment. The CHF of the super-hydrophilic PCB heater was enhanced by a maximum of 28% at an inclination angle of 45°; the enhancement reduced as the inclination angle increased.