Superior influence of surface wickability over surface morphology on critical heat flux enhancement during quenching in liquid nitrogen

Abstract

Our group developed a surface modification technique suitable for polymeric materials, in which sacrificial sugar particles were sprayed to generate amplified surface roughening, successfully inducing prominent critical heat flux (CHF) enhancement under cryogenic conditions. In this study, we set out to further investigate the implications of our technique, by exploring the variation of the nozzle-to-sample distance and its effect on the surface profile created. It was found that as the spraying distance increased (up to 50 cm), the CHF from the generated surface increased to an optimal point (285%). By performing a thorough characterization of the surface, it was found that the roughness and wickability of these surfaces increased proportionally up to this point. Once the distance increased beyond the optimum, we observed a more complex phenomenon between the surface roughness and the wickability, which could be attributed to the topographical features of the surface generated as the distance increased. Considering these early findings, we intend to direct and motivate further studies into these phenomena that could eventually clarify the controversy regarding the attribution to either surface roughness or wickability as the main drivers of CHF enhancement.