Influence of surface roughness and Wettability of novel surface on nucleate boiling performance in deionised water at atmospheric pressure

Abstract

Pool boiling is one of the very suitable techniques for an efficient thermal management system dealing with two-phases. The present work deals with the experimental exploration of critical heat flux for safety concern and heat transfer coefficient related to the performance point of view in nucleate boiling regime of pool boiling system. The copper substrate was coated with porous copper nanoparticles by sputtering technique to the thicknesses of 250 nm, 500 nm, and 750 nm. The surface characteristics of the copper nanocoated surfaces have been analysed as a result of wettability, surface roughness, and micro-structure. The contact angle goniometer, stylus profilometer, XRD, and SEM have been employed to analyze the surface structure. The maximum augmentation of critical heat flux was 59% for the thickness of 750 nm as compared to plain copper substrate. A 99% increase in the heat transfer coefficient was achieved for 750 nm thickness surface in comparison with the plain copper surface. The tremendous augmentation in critical heat flux and heat transfer coefficient was achieved due to wetting and rewetting properties of the deionized water on the copper nanocoated surfaces. The capillary action on the copper nanostructure improves the fluid supply to the test surface and removes the heat at low wall superheat than the plain copper surface. The average roughness of the copper nanocoated surface augments the heat transfer area which tends to enhance the performance factor significantly.