Influence of TiO 2 thin film on critical heat flux and performance enhancement of pool boiling at atmospheric pressure

Abstract

An increase in the rate of heat generation due to the compactness and performance enhancement of electronics equipment has been observed in the recent years. Though the efficient heat recovery to improve safety and to increase the life span of the equipment is a challenging task, Pool boiling is considered as a technique to recover an abundant quantity of heat at minimum wall superheat. The performance and safety factors are explored using boiling heat transfer coefficient and critical heat flux. The present investigation is carried out on a plain copper surface and copper surface coated with TiO₂ thin film with three different thicknesses, namely 250, 500 and 750 nm. This work also explores the influence of wettability and roughness of the TiO₂ thin film coated surfaces. The morphological and structural studies are conducted by scanning electron microscopy and x-ray diffraction scanning electron microscopic patterns. The critical heat flux of TiO₂ thin film coated surface at 750 nm thicknesses was better augmented by 69% than the plain copper surface. The heat transfer coefficient was better augmented by 117% than the uncoated copper surface. The excellence in hydrophillic nature of the TiO₂ thin film creates numerous nucleation sites which in turn enhance the capillary wicking. The continuous wetting and rewetting characteristics of the TiO₂ thin film enhance the critical heat flux and boiling heat transfer coefficient.