中文摘要：

对加热长度为4．5mm、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。

英文摘要：

The heat transfer characters of nanofluids in the micro-channel chip with the heating length of 4. 5 mm and hydraulic diameter of 130μm was studied. The heat transfer performances of the pure water and nanofluids with different mass fractions were compared. The effects of the thermal boundary layer development on the heat transfer performance of the nanofluids were analyzed. The experimental results show that the addition of the nanoparticles can improve the local heat transfer coefficient of the micro-channel in the thermal boundary layer development zone, and the increase amplitude of the heat transfer coefficient decreases gradually along the direction of refrigerant flow. In the thermal boundary layer development zone, the higher the refrigerant inlet velocity, the larger the increase amplitude of the heat transfer coefficient of nanofluids. Finally, the reasonable explanation for experimental results was proposed by the theoretical analysis. It is concluded that in thinner thermal boundary layer, the nanofluids have greater impact on the local heat transfer coefficient, and the heat transfer enhancement is better.