为了提高电子器件的散热能力,减少高温引起的器件性能降低和寿命缩短的问题,对多孔微通道平行流扁管单相对流换热在发展段高热流下的流动特性和换热能力进行对比研究,并从单双面加热、不同消除接触热阻的方法和不同热流密度3个方面对微通道发展段的换热能力的影响进行评价.该通道水力直径Dh=1.09 mm,高宽比α=0.85,雷诺数Re=206~4553.实验结果显示:发展段的摩擦阻力特性层流区与经典理论较为吻合;实验管段单面加热比双面加热在换热能力上有明显增强,但随着Re的增加差距降低;消除接触热阻的方法对换热的影响差别明显不能忽略,采用钎焊的方法与填充导热硅脂的方法相比,可使加热件表面温度降低10℃;在Re<1000时,流体黏性变化对换热的影响较为明显,在高Re区域,不同热流密度下Nu值基本一致.%In order to improve the heat dissipation of electronic devices, reduce the problem of lower devices performance and short working life which was caused by high temperature, the friction and heat transfer characteristics of single phase forced convection in developing region with high heat flux through a multiport microchannel flat tube ( MMFT) were comparatively investigated by experiments. Furthermore the influence of heat transfer capability in MMFT with developing flow was evaluated by three aspects:single/double-side heating, different methods of eliminating thermal resistance and different heat flux. The hydraulic diameter of the tube was 1. 09 mm, aspect ratio was 0. 85 and Reynolds number was in the range of 206~4553 . The results indicate that friction factor obtained by experiment is in good agreement with the classical developing channel laminar flow theory. In addition to heat transfer, single-side heating is superior to double-side heating whereas the discrepancy reduces with the increase of Reynold number. Different thermal resistance has obvious effect on heat transfer. Brazing lowers the surface temperature of heating device 10℃ than thermally conductive silicone grease. When Re<1000, temperature dependent viscosity variation on the convective heat transfer are significant, however for high Reynold, various heat flux effects Nusselt number little.
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