高粘度熔盐纳米流体强制对流传热关键问题研究

Molten salt is the key working medium of heat storage and transfer for solar thermal power generation. With the development of the technology of water nanofluids as the representative for nanofluids, the researches on improving the heat storage and transfer capacity by adding nanoparticles have been paid more and more attention. The high viscosity of the molten salt nanofluids and the electrostatic repulsion between the nanoparticles are the key factors that affect the heat transfer enhancement, which are different from water nanofluids. The project focuses on the technology of heat storage and transfer for solar thermal power generation and takes the affection of the self-characteristics of molten salt nanofluids on the forced convection heat transfer as study object. The performances of flow and forced convection heat transfer of molten salt nanfluids with high viscosity under high temperature are experimentally studied, as well as the affection of basic properties and concentration of nanoparticles on the forced convection heat transfer of molten salt nanofluids with high viscosity. The best nanoparticle concentration, species and particle size distribution of enhanced convective heat transfer are also explored. The process of forced convection heat transfer of molten salt nanofluids with electrostatic repulsion between nanoparticles is analyzed by theoretical simulation. The mechanism of electrostatic repulsion between nanoparticles on the heat transfer enhancement of nanoparticles micro motion is explored. The study of this project not only provides theoretical and experimental data for the application of heat storage and transfer materials of high performance molten salt nanofluids and the design of heat storage and transfer equipment, but also is of great significance for the knowledge enrichment of the laws of heat transfer and the mechanism of heat transfer enhancement of complex fluid with high viscosity.

熔盐是太阳能热发电中的关键蓄热传热工质。随着以纳米水流体为代表的纳米流体技术的发展，通过添加纳米粒子提高熔盐蓄热传热能力的研究受到了广泛关注。与纳米水流体不同的是，熔盐纳米流体高粘度和纳米粒子间静电排斥力是影响强化传热的关键因素。为此，本项目着眼于太阳能热发电中蓄热传热技术，以熔盐纳米流体自身特性对强制对流传热的影响为研究对象，实验研究高温下高粘度熔盐纳米流体流动和强制对流传热特性，以及纳米粒子基本属性和浓度对高粘度熔盐纳米流体强制对流传热的影响规律，探寻强化对流传热的最佳纳米粒子浓度、种类和粒径分布；理论模拟分析存在纳米粒子间静电排斥力的熔盐纳米流体强制对流传热过程，探索纳米粒子间静电排斥力对纳米粒子微运动强化传热的作用机制。本项目的研究，不仅可为高性能熔盐纳米流体传热蓄热材料应用和传热蓄热设备设计提供理论和实验数据支撑，同时也对丰富高粘度复杂流体传热规律和强化传热机理知识具有重要意义。

本项目着眼于太阳能热发电中的蓄热传热技术，以强化熔盐纳米流体的强制对流传热性能为目标，研究了高温下高粘度的熔盐纳米流体自身特性对强制对流传热的影响。通过理论分析和试验研究相结合的方法，对高温下高粘度的熔盐纳米流体的强制对流传热特性进行了深入的研究。研究了高粘度对熔盐纳米流体强制流动和传热特性的影响规律，探明了纳米粒子基本属性和浓度对高粘度熔盐纳米流体强制对流传热的影响规律，获得了强化高粘度熔盐纳米流体强制对流传热的最佳纳米粒子浓度、种类和粒径分布，获得了适用于熔盐纳米流体对流传热规律的无量纲准则数关联式，开发了一种热物性及稳定性优秀的熔盐纳米流体。通过本项目研究成果，可为熔盐纳米流体在太阳能热发电蓄热传热系统上的实际应用提供理论依据和技术支持。