Experimental Study On Flow Boiling Heat Transfer Characteristics And Visualization Of Micro/Mini Channel

The microscale channel enhancement technology of heat transfer has important potential applications in areas such as microelectronics, aerospace and chemical engineering. It has been studied by domestic and foreign researchers recently. This paper regarded the flow boiling heat transfer characteristics and visualization of the smooth and micro-porous surface in micro/mini channels as to research content, which had important academic significance and practical value.The results of flow boiling test in the smooth surface in the micro/mini channel showed that:when taking FC72 as the medium, decrease the channel size and reduce the mass flow rate could effectively strengthen the flow boiling heat transfer in subcooled boiling and earlier saturated boiling by enhancing the confinement effect of the bubbles. Excessive bubble confinement effect was caused with the further increase of dryness. which hindered the rewet of the channel's surface and worsened the heat transfer. When taking water as the medium, decrease the channel size could effectively strengthen the entire flow boiling heat transfer process and reduce the flow rate had an adverse effect on the heat transfer. The two mediums resulted in different effluence on heat transfer when changing the channel size and the mass flow rate, which mainly dued to different wettability in the heat transfer interface. Sinter the micro-porous layer in the surface of the micro/mini channel could enhance the heat transfer, and the peak enhancement multiples is 4.3 when taking water as the medium, while decrease the channel size and reduce the mass flow rate could weaken the enhanced effect. The micro-porous surface not only provided a lot of vaporized core but also improved the wettability of water in the channel surface, which can avoid drying out on smooth surface. When the channel size was too small and the flow rate was too low, a greater adhesion force on the bubbles generated in the micro-porous surface, which had an adverse affect on the heat transfer. Channel size, dielectric properties, the mass flow rate were the determinants of the scale effect.