One of the most common solutions currently available to meet future energy needs in the world is concentrated solar power (CSP) plants combined with thermocline thermal energy storage (TES) tank subsystems. The air rock thermocline TES tank asserts to be an effective and inexpensive TES subsystem for CSP plants. In this study, a discrete element method (DEM) combined with a numerical model of computational fluid dynamics (CFD) was adopted to investigate the thermal performance of a scale model of an air rock thermocline TES tank. The study is carried out to optimize TES thermocline tank's thermal behavior by changing the heat transfer fluid (HTF) inlet velocity. The DEM–CFD coupled model is validated against analytical and experimental data. The results show that the use of the distributor reduced the influence of the wall effect by distributing the HTF in a regular way as the fluid passes through it, especially at high inlet velocity. Moreover, the results show that each TES tank subsystem has a critical velocity at which the tank operates most efficiently. Furthermore, the results demonstrated that the maximum value of the overall cycle efficiency was equal to 70.15% at 10 m/s, while the minimum value was equal to 42.5% at 2 m/s. The highest capacity and utilization ratio are 81.31 and 72.81% at 16 m/s, while the lowest capacity and utilization ratio are 52.01 and 44.75% at 2 m/s. The pumping energy needed to overwhelm the pressure drop rises when the HTF inlet velocity increases. This study can provide an effective reference for the efficient operation regulation and optimal design of the thermocline tank.

Graphic abstract

中文翻译：

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使用耦合DEM–CFD方法对集中式太阳能发电厂的空气岩石温跃层TES储罐进行性能分析

当前可满足全球未来能源需求的最常见解决方案之一是集中太阳能发电（CSP）电厂与热线热能存储（TES）储罐子系统的组合。空气岩温跃层TES储罐被认为是CSP工厂有效且廉价的TES子系统。在这项研究中，采用离散元方法（DEM）结合计算流体动力学（CFD）的数值模型来研究气石温升TES储罐比例模型的热性能。通过更改传热流体（HTF）的入口速度来进行研究，以优化TES恒温槽的热性能。DEM–CFD耦合模型针对分析和实验数据进行了验证。结果表明，分配器的使用通过在流体通过HTF时（尤其是在高入口速度时）以规则的方式分配HTF来减少壁效应的影响。而且，结果表明，每个TES储罐子系统都有一个临界速度，该速度可使储罐最有效地运转。此外，结果表明，总循环效率的最大值在10 m / s时等于70.15％，而最小值在2 m / s时等于42.5％。在16 m / s时，最高容量和利用率为81.31和72.81％，在2 m / s时，最低容量和利用率为52.01和44.75％。当HTF入口速度增加时，压倒压降所需的泵送能量就会增加。

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