Natural convection heat transfer of molten salt is widely used in concentrated solar plants, such as the solar receiver, the single‐tank thermal energy storage system, and so forth. Meanwhile, adding nanoparticles into molten salts to form nanofluids can obviously improve the thermal properties of the working medium. However, the heat transfer performance of the molten salt‐based nanofluids has not been investigated extensively, and the action mechanism between base fluids and nanoparticles is still unclear. In the present work, a lattice Boltzmann model considering fluid and nanoparticles as two different phases was developed, and various interactions were taken into consideration. Meanwhile, the effects of nanoparticle concentrations, aspect ratios of the rectangular vessel, and Ra on natural convection heat transfer of solar salt‐based SiO₂ nanofluids were analysed. The results show that specific heat capacity contributes substantially to heat transfer for all aspect ratios, and the maximum enhancement of natural convection heat transfer is obtained with a mass fraction of 1.0%. However, increase in Ra intensifies the effect of viscosity and weakens the heat transfer enhancement. Through interaction analysis, it indicated that nanoparticles tend to be driven to the top area of the rectangular vessel by temperature difference, driving force, and drag force. Meanwhile, a Nu enhancement contour was provided to optimize the design of a single energy storage tank.

中文翻译：

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通过优化矩形容器设计来调节SiO2-太阳盐纳米流体的自然对流传热

熔融盐的自然对流传热被广泛用于集中式太阳能发电厂，例如太阳能接收器，单罐式热能存储系统等。同时，将纳米颗粒添加到熔融盐中形成纳米流体可以明显改善工作介质的热性能。但是，尚未对熔融盐基纳米流体的传热性能进行广泛研究，并且基液与纳米颗粒之间的作用机理仍不清楚。在当前的工作中，开发了将流体和纳米颗粒视为两个不同相的格子玻尔兹曼模型，并考虑了各种相互作用。同时，纳米颗粒浓度，矩形容器的长宽比和Ra的影响分析了太阳盐基SiO ₂纳米流体的自然对流传热。结果表明，在所有纵横比下，比热容量都对传热有很大贡献，并且自然对流传热的最大增强率是1.0％。然而，Ra的增加增强了粘度的作用并且削弱了传热的增强。通过相互作用分析表明，纳米颗粒倾向于被温度差，驱动力和拖曳力驱动到矩形容器的顶部。同时，提供了Nu增强轮廓以优化单个储能罐的设计。