矩形微槽道纳米流体饱和沸腾临界热流密度特性

针对纳米流体在微小尺度传热领域的应用,在常压下对微槽道中纳米流体的流动沸腾临界热流密度进行实验研究。分别以体积浓度为0.2%、0.5%的水基Al2O3纳米流体为工质进行试验,研究不同质量流速、槽道尺寸以及体积浓度等因素对沸腾CHF的影响。对比水为工质实验结果,表明:槽道尺寸、质量流速对于水-Al2O3纳米流体和纯水的CHF影响一致。其它参数一定的工况下,纳米流体CHF比纯水大,且随着纳米流体体积浓度增大,出口壁面过热度会增大。最后介绍一个微槽道沸腾CHF的预测模型,在评价其不足的基础上提出一个关于CHF的预测公式,与实验数据进行对比,验证该公式的适用性。

Properties of saturated flow boiling critical heat flux of nanofluids through rectangular micro-channel

For the application of nanofluids in the field of heat transfer in micro-channels,experiment was carried out at atmospheric pressure to understand characteristics of the critical heat flux(CHF) of nanofluids in micro-channels.The working medium were respectively the water based on Al2O3 nanofluids with volume concentrations being 0.2% and 0.5%.The thesis was mainly about the change of boiling CHF with different mass velocity,scale of channels,volume concentration and so on.Results show that CHF of both woking medium has the same changing with the increasing of mass velocity and the diameters of channels.CHF of nanofluids is larger than that of water with the same parameters,and the outlet degree of superheat of nanofluids decrease when volume concentrations increas.A new model to predict CHF conditions in microchannels was introduced.A new formula to predict CHF was raised based on the model.The experimental data in this study obtained from micro-channels were used to test universal applicability of the formula.