An analysis of pool boiling heat transfer on nanoparticle-coated surfaces

In the present study, copper surfaces were deposited with Cu-Zinc nanoparticles of 0.6 mg by an electrophoretic deposition method (EPD). Two deposition patterns were designed, i.e., fully deposition (EPD-F) and channel-pattern deposition (EPD-C). In the channel-pattern deposition, the smooth channel and the deposition channel occur alternatively, by keeping the width of the smooth channel as 3 mm, but the width of the deposition channel as 1 mm (EPD-C1) and 3 mm (EPD-C2), respectively. Pool boiling of HFE-7200 was studied on a smooth surface and the nanoparticle-coating surfaces. The results showed that the surface with fully deposition (EPD-F) had the highest heat transfer coefficient, around 100% enhancement compared with the smooth surface, while the surface with channel-pattern deposition (EPD-C2) had the highest critical heat flux, around 33.3% enhancement in comparison to the smooth surface. A high speed camera was used to study bubble dynamics, which indicated that the nanoparticle-coating surfaces had smaller bubble departure diameters and higher departure frequencies. A heat transfer model, considering natural convection, re-formation of thermal boundary layer and microlayer evaporation, was formulated to predict the heat transfer on the test surfaces, showing good prediction at low and moderate heat fluxes. CHF was analyzed from the perspective of the Rayleigh Taylor instability. (C) 2019 The Authors. Published by Elsevier Ltd.