Experimental Study of Nucleate Pool Boiling Heat Transfer Using Water on Thin-Film Surface

Abstract

A novel surface modification approach, viz. electron beam evaporation method, was proposed for fabrication of nanoparticle-coated thin-film surface. The nucleate pool boiling heat transfer performance of untreated, treated, treated with titanium oxide and silicon oxide thin-film surfaces was experimentally investigated at atmospheric pressure. The surfaces were characterized with respect to contact angle, roughness, topography by contact angle analyzer and coating thickness, respectively. The contact angle was measured by sessile droplet method. The optical surface profiler is used for the measurement of surface roughness. Heat flux was varied from 50 to 145 W/cm2 in eight steps. In each run, heat transfer coefficient was calculated from the experimental data. After analyzing the data, it is found that thin-film surface is superior from the point of boiling heat transfer coefficient than other surfaces. The results showed a maximum of 45 and 60 % enhancement in heat transfer coefficient for higher thickness of silicon oxide and titanium oxide thin-film surface as compared to untreated surface. The highest enhancement of heat transfer coefficient in thin-film surfaces was due to level of wettability improvement, enhanced surface roughness and creating high-density active nucleate site on the surface. The experimental data were predicted with other published data, and some deviations in heat transfer coefficient were observed. The deviation of result compared with other published data is due to the operating conditions, surface types, coating thickness and method of coating.