Abstract:

Nanofluids have been found to be widely used in many fields as new heat transfer medium. The results indicate that the main factors leading to the change of the heat transfer performance of nanofluids are the deposition of nanoparticles on the heat transfer surface, the change of the surface roughness of the heating surface, the change of the surface tension of the medium, the internal energy transfer and the bubble formation condition. The experimental study on pool boiling of water-based SiO₂ nanofluids was carried out with different particle size of nanoparticles to obtain the difference of heat transfer characteristics between SiO₂/water nanofluids and deionized water in the state of nucleate boiling in the saturated state, and to compare the heat transfer characteristics of nanofluids with different particle diameters. The results show that the heat transfer characteristics of nano-particles are quite different from that of the pure base fluid in the same state. The change of heat transfer characteristics between different particle sizes is obvious and the change of heat transfer characteristics does not increase linearly with the increase of particle size.

Key words: water-based, nanofluids, boiling, heat transfer characteristics, particle size

摘要：

纳米流体作为新型换热介质可广泛应用于多个领域。现有研究结果表明导致纳米流体沸腾换热性能变化的因素主要在于纳米颗粒在换热表面的沉积、加热表面粗糙度、表面张力、内部能量传递、气泡形成条件等。对水基SiO₂纳米流体进行池沸腾实验研究，得到SiO₂/水纳米流体与纯基液-去离子水核态沸腾换热特性的区别，比较不同颗粒粒径对纳米流体换热特性影响。结果表明：对于低浓度纳米流体，添加纳米颗粒后流体的换热特性与纯基液在相同条件下进行核态沸腾时的换热特性有较大差异，不同粒径之间换热特性变化明显，随着粒径的增加呈非线性增长趋势，随着热通量增大纳米颗粒粒径对换热特性的影响趋势增大。

关键词: 水基, 纳米流体, 沸腾, 换热特性, 粒径