Pool Boiling Heat Transfer of Hydrophobic Surfaces with Different Dynamic Wetting Characteristics

Abstract

Present work reports the importance of dynamic wetting characteristics of a surface in pool boiling heat transfer and bubble growth dynamics. Although hydrophobic surfaces possess better nucleation behavior, they have earned less attention in pool boiling applications due to their early premature transition from efficient nucleate boiling regime to inefficient film boiling regime. Hydrophobic surfaces with high contact angle hysteresis named parahydrophobic surfaces can be used in pool boiling applications insofar as the receding contact angle is adequately small to prevent vapour from spreading on the surface broaden the nucleate boiling regime. In this work, two parahydrophobic surfaces have been prepared using the atmospheric plasma spray coating technique. A superhydrophobic surface is also prepared using the chemical deposition method. Saturated pool boiling experiments have been performed with DI water on both types of hydrophobic surfaces, and results are compared with a plain reference copper surface. Experimental results confirmed that, unlike superhydrophobic surfaces, parahydrophobic surfaces exhibiting petal effects are capable of boiling up to high heat fluxes just like plain copper surfaces. Due to the low receding contact angle, the surface with low wettability has still achieved the same critical heat flux (CHF) value as the plain surface.