Experimental investigation on spray cooling with low-alcohol additives

Abstract

In the present study, the spray-wall impingement characteristics and heat transfer performance during spray cooling were experimentally investigated to ascertain the effect of different low-alcohol additives in water. The surface tension and contact angle on the heating surface were measured and the images of spray wall interaction were taken. The spray cooling performance of alcohol-water mixtures were compared with pure water. The results indicated that adding a small amount of alcohol to water can significantly decrease the surface tension and contact angle. It is also an effective way to enhance the heat dissipation and to control the surface temperature simultaneously. As the alcohol content increases, the intensity of heat transfer capacity enhancement increases first and then weakens slightly. The optimal concentrations of ethanol, n-propanol and iso-propanol corresponding to the best heat transfer performance are respectively 4 vol%, 4 vol% and 2 vol%, and the maximum heat transfer coefficient is achieved with 4 vol% ethanol-water mixture. The correlation of Nusselt number, which is associated with the physical properties, the Weber, Prandtl, Jacob as well as Reynolds numbers, is also presented with an error of 15%.