Flow boiling heat transfer enhancement on copper surface using Fe doped Al2O3–TiO2 composite coatings

Abstract

In the present work, flow boiling experiments were conducted to study the effect of spray pyrolyzed Fe doped Al2O3–TiO2 composite coatings over the copper heater blocks on critical heat flux (CHF) and boiling heat transfer coefficient. Heat transfer studies were conducted in a mini-channel of overall dimension 30mm×20mm×0.4mm using de-mineralized water as the working fluid. Each coated sample was tested for two mass fluxes to explore the heat transfer performance. The effect of Fe addition on wettability and porosity of the coated surfaces were measured using the static contact angle metre and the atomic force microscope (AFM), and their effect on flow boiling heat transfer were investigated. A significant enhancement in CHF and boiling heat transfer coefficient were observed on all coated samples compared to sand blasted copper surface. A maximum enhancement of 52.39% and 44.11% in the CHF and heat transfer coefficient were observed for 7.2% Fe doped TiO2–Al2O3 for a mass flux of 88kg/m2s.