Abstract: In recent years, due to the improvement of power density, compact packaging and high performance requirements, the heat dissipation demand of high heat flux devices has increased significantly. In view of the above problems, this work plans to use the spray cooling technology to conduct heat transfer research on the Al2O3 nanofluid with ethylene glycol water as the base fluid, focusing on the analysis of the influence of the concentration of the base fluid, the concentration of nanoparticles, and the concentration of the added dispersant on the heat transfer performance of the working medium spray cooling at three different operating conditions of 300, 500, and 700 W. The experimental results show that due to the decrease of specific heat capacity and thermal conductivity and the deterioration of spray characteristics, the mass fraction of ethylene glycol increases from 30wt% to 80wt%, and the surface heat transfer coefficient of Al2O3 nanofluid solution decreases continuously, with an average decrease of 41.63%. The surface heat transfer coefficient of Al2O3 nanofluid shows a trend of first decreasing, then increasing, and then slowly decreasing with the increase of nanoparticle mass fraction. When the mass fraction of Al2O3 nanoparticles increases from 0 to 2wt%, the overall average surface heat transfer coefficient of Al2O3 nanofluid solution decreases by 6.94%. The deposition and bubbling effect are the main reasons for weakening the heat transfer. At the same time, the increase in the mass fraction of nanoparticles improves the thermal conductivity of the nanofluid solution, which to some extent enhances heat transfer. In addition, the addition of a low-quality non-ionic surfactant (Tween-20) can improve the foaming effect, making the heat transfer coefficient of spray cooling increase by about 1.52%, but still lower than that of pure base liquid; Adding a higher mass fraction of dispersant can cause aggregation between nanoparticles and further weaken the heat transfer performance of the thermal conductivity solution.

Key words: spray cooling, glycol, nanoparticles, dispersant, heat exchange

摘要： 近年来，由于功率密度的提高、紧凑的封装以及高性能的要求，高热通量器件的散热需求显著增加。针对上述问题，本工作拟采用以喷雾冷却的技术方法对以乙二醇-水为基液的Al2O3纳米流体展开传热研究，重点分析了在300, 500和700 W三种不同工况下，基液浓度、纳米颗粒浓度、所添加分散剂的浓度对工质喷雾冷却换热性能的影响。实验结果表明，由于比热容和导热系数的降低以及喷雾特性的恶化，乙二醇质量分数由30wt%增至80wt%，Al2O3纳米流体溶液表面传热系数不断下降，平均降低41.63%。Al2O3纳米流体表面传热系数随着纳米颗粒质量分数的增加呈现先减小后增加，再缓慢减小的趋势。Al2O3纳米颗粒质量分数由0增至2wt%，Al2O3纳米流体溶液表面传热系数整体平均下降6.94%，沉积和泡化效应是削弱换热的主要原因。此外，添加低质量分数的分散剂聚山梨醇酯-20 (Tween-20)可以改善泡化效应，使得喷雾冷却传热系数增高约1.52%，但仍低于纯基液(不添加纳米颗粒)的换热能力；添加较高质量分数的分散剂会导致其换热性能进一步削弱。

关键词: 喷雾冷却, 乙二醇, 纳米颗粒, 分散剂, 传热