倾斜微槽道热管中纳米流体的应用

为了研究热管倾斜角度和压力对热管蒸发段、冷凝段传热系数以及最大换热功率的影响,对使用水基CuO纳米流体为工质的倾斜微槽道热管强化换热特性进行实验研究.实验装置主要由带角度调节功能的微槽道热管和加热、冷却系统组成.实验结果发现,用水基纳米流体替代去离子水为工质时,热管整体换热特性得到明显增强,蒸发段、冷凝段传热系数以及最大功率都能大幅度提高,总热阻明显降低.倾斜水热管的蒸发段和冷凝段传热系数比水平水热管的有大幅提高,但最大功率变化不大.而倾斜纳米流体热管不但蒸发段和冷凝段传热系数比水平纳米流体热管有大幅提高,而且最大功率更有接近一倍的增加.对水和纳米流体两种工质,对应于最佳换热特性的倾斜角都是75°.因此,纳米流体对倾斜热管有良好的应用前景.

Application of nanofluids in an inclined axial miniature grooved heat pipe

An experiment was performed to investigate the thermal performance of inclined miniature grooved heat pipe using water-based CuO nanofluids.The study focused on the effects of the inclination angle and the operating pressure on the heat transfers of both the evaporator and condenser as well as the maximum heat flux of the heat pipe.The nanofluid consists of pure water and CuO nanoparticles with a mean diameter of 50nm.The mass concentration of the nanofluid was fixed at an optimal value of 1.0%.The experimental results show that the inclination angle has a very significant effect on both the total heat resistance and maximal power of the heat pipe using water,and only a slight effect on those of the heat pipe using nanofluids.There exists an optimal inclination angle which corresponds to the best thermal performance,and this angle is 75° for both heat pipes using water and nanofluids.For the inclined heat pipe using nanofluids,not only the evaporation and condensation heat transfer coefficients are greatly increased,but also the maximal power can be almost doubled as compared with those of the heat pipe using water.The present investigation discovers that the thermal performance of an inclined miniature grooved heat pipe can be evidently strengthened by using CuO nanofluids.