线性菲涅尔熔盐纳米流体聚光集热系统光-热-流-固耦合特性研究

Solar linear Fresnel reflectors (LFR) are attractive because of low cost and optimal utilization of land area. However, there are some problems with the system such as low concentration ratio and uneven heat flux distribution with the solar collector, which result in high local temperature of the collector, large thermal stress and deformation, low heat collection efficiency of the system. In view of the above problems, this research proposes a solar-thermal-fluid-solid coupling method for the thermal collector system of linear Fresnel molten salt nano-fluids. Firstly, the distribution and optimization of solar radiant energy flow on the surface of the collector of the linear Fresnel collector system are studied by numerical simulation and experimental methods. Secondly, the flow and heat transfer enhancement characteristics of molten salt nano-fluid in tube are studied experimentally. Finally, the solar-thermal-fluid-solid coupling model of the linear Fresnel molten salt nano-fluid heat collecting system is established, and the optimization of the linear Fresnel molten salt nano-fluid heat collecting system is studied. This study will enrich and develop the knowledge system of solar linear Fresnel system, and provide theoretical basis and technical support for the application of solar linear Fresnel system with molten salt nano-fluid.

线性菲涅尔太阳能聚光集热系统具有成本低、空间利用率高等优点，但存在聚光比低，系统集热器能流分布严重不均匀等问题，导致集热器局部温度过高，热应力变形大，系统集热效率低。针对以上问题，本项目提出了线性菲涅尔熔盐纳米流体聚光集热系统光-热-流-固耦合优化方法，首先采用数值模拟和实验方法对线性菲涅尔聚光集热系统集热器表面太阳辐射能流分布进行优化研究；其次实验研究熔盐纳米流体的管内流动与传热强化特性；最后通过建立线性菲涅尔熔盐纳米流体聚光集热系统光-热-流-固多因素耦合模型，对线性菲涅尔熔盐纳米流体聚光集热系统进行动态优化研究。本研究为发展和完善线性菲涅尔聚光集热系统科学理论做出补充，为线性菲涅尔熔盐纳米流体聚光集热系统的应用提供理论依据与技术支持。

线性菲涅尔太阳能聚光集热系统是太阳能热利用重要的方式，具有成本低、空间利用率高等优点。本项目以线性菲涅尔聚光集热系统为研究对象，以自主研发的低熔点四元混合硝酸盐为传热蓄热介质，通过添加不同纳米粒子制备熔盐纳米流体，开展了熔盐纳米流体在光管和不同类型强化管内对流换热特性研究，获得了熔盐纳米流体在光管和不同类型强化管内流动传热关联式，通过对熔盐纳米流体内部微观结构表征分析，阐明熔盐纳米流体传热强化的内在机理，揭示影响熔盐纳米流动传热性能的关键因素。基于蒙特卡洛光线追踪法，采用了构建光学模型的研究方法，以真空集热管表面能流分布均匀度为目标，采用多目标优化遗传算法对线性菲涅尔系统真空集热管表面能流分布进行优化研究从而获得一次镜场和二次聚光器的最优结构参数，揭示二次聚光器结构参数与真空集热管表面能流分布的微观光学作用机理。建立了线性菲涅尔聚光集热系统光-热-流-固多物理场耦合模型，揭示了线性菲涅尔聚光集热系统多物理场之间的作用机制，在太阳能聚光集热系统特别是线聚焦太阳能系统具有重要的科学研究价值的广泛的研究前景。