Study on heat transfer and flow instability in open microchannels

The flow boiling heat transfer characteristics of deionized water in open microchannels and smooth copper surfaces were studied. The boiling curves, heat transfer coefficient and pressure drop characteristics were obtained at different mass fluxes. The results show that at three mass flow rates, the critical heat flux and heat transfer coefficient of the open microchannel are generally higher than those of the smooth copper surface, while the average pressure drop characteristics are the opposite. Moreover, the open microchannel can improve the backflow phenomenon to a certain extent, thus reducing the wall temperature. Although the average pressure drop of the open microchannel is 23.6%—43.3% higher than that of the smooth copper surface, the average inlet pressure standard deviation is 54.0%—62.5% lower than that of the smooth copper surface, and the flow instability of the open microchannel can be greatly alleviated by reducing the mass flux compared with the smooth copper surface.