An experimental study on flow boiling characteristics of phema nano-coated surfaces in a microchannel

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In this study, the effect of pHEMA (Polyhydroxyethylmethacrylate) nanostructure coated surfaces on flow boiling was investigated in a rectangular microchannel. Experiments were conducted using deionized water as the working fluid to investigate flow boiling in a microchannel with dimensions of 14 cm length, 1.5 cm width, and 500 mu m depth. The effect of pHEMA coatings (coated on 1.5 x 1.5 cm(2) silicon plates) on heat transfer coefficients and flow patterns was assessed and supported using a high speed camera system. Although the contact angle decreases on nano-coated surfaces, due to surface porosity, boiling heat transfer coefficient increases. Furthermore, visualization results indicated that uncoated surfaces experienced a smaller nucleate boiling region. It was also observed that dryout occurs at higher heat fluxes for coated surfaces.