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对加热长度为4.5 mm、水力直径为130μm的微通道芯片中纳米流体的换热情况进行了实验研究,比较了纯水和不同质量分数纳米流体在微通道中的换热性能,分析了热边界层发展对纳米流体换热性能的影响。实验发现,在热边界层发展段,纳米粒子的加入可使通道的局部换热系数得到提高,且沿着工质的流动方向,换热系数提高的幅度逐渐减小。在热边界层发展阶段,工质的进口速度越大,纳米流体换热系数提高的幅度也越大。最后通过理论分析对产生上述实验现象的原因进行了合理解释,并得出热边界层越薄,纳米流体对于局部换热系数的影响越大,对于传热的强化效果也越好。
The heat transfer of nanofluids in microchannel chips with a heating length of 4.5 mm and a hydraulic diameter of 130 μm was investigated experimentally. The heat transfer performance of pure water and nanofluids with different mass fractions in microchannels was compared. The thermal boundary Effect of layer development on heat transfer performance of nanofluids. The experimental results show that the local heat transfer coefficient increases with the addition of nano-particles in the development of thermal boundary layer, and the increase of heat transfer coefficient decreases along the flow direction of working fluid. During the development of the thermal boundary layer, the greater the inlet velocity of the working fluid, the greater the increase of the heat transfer coefficient of the nanofluid. Finally, the reasons for the above experimental phenomena are reasonably explained through theoretical analysis, and the thinner the thermal boundary layer, the greater the influence of nanofluids on the local heat transfer coefficient and the better the heat transfer enhancement effect.