Abstract Thermocline characteristics and the discharge performance of a molten-salt packed-bed energy storage system are analyzed numerically. For this purpose, a transient two-dimensional model based on local non-equilibrium thermal theory in a porous medium is developed. Three different solid fillers are utilized, including that of quartzite rock, slag pebbles, and alumina ceramics. Molten-salt serves as a heat transfer fluid (HTF). The effects of fluid inlet flow rate and the particle size diameter on the thermocline thickness through temperature profiles of packed-bed systems have been investigated. The discharging power is discussed in a detailed description of various operating conditions through the discharge outlet temperature stability period. The results obtained are compared with that of the pure molten-salt tank. It is revealed that the thermocline thickness of the molten-salt packed-bed tank is higher than that of pure molten-salt tank, while the latter is better in thermal stratification. As the inlet flow rate increases, both the discharging power and thermocline thickness increase. The results also indicated that decreasing particle size diameter, results in a decrease in thermocline thickness, and the discharging performance becomes more stable. Slag pebbles as a filler material is more effective than quartzite rock in thermal energy storage (TES). The results can be beneficial for the design and optimization of the packed-bed thermocline tank.

中文翻译：

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以熔盐为传热流体的固体填充床温跃层罐的动力学特性

摘要 数值分析了熔盐填充床储能系统的跃跃层特性和放电性能。为此，开发了基于多孔介质中局部非平衡热理论的瞬态二维模型。使用三种不同的固体填料，包括石英岩、矿渣卵石和氧化铝陶瓷。熔盐用作传热流体 (HTF)。通过填充床系统的温度分布研究了流体入口流速和粒径对温跃层厚度的影响。在通过排放出口温度稳定期的各种操作条件的详细描述中讨论排放功率。所得结果与纯熔盐罐的结果进行了比较。结果表明，熔盐填充床储罐的温跃层厚度高于纯熔盐储罐，而后者在热分层方面更好。随着入口流速的增加，放电功率和温跃层厚度均增加。结果还表明，减小粒径，导致温跃层厚度减小，放电性能变得更加稳定。在热能储存 (TES) 方面，矿渣卵石作为填充材料比石英岩更有效。研究结果有助于填充床温跃层储罐的设计和优化。放电功率和温跃层厚度均增加。结果还表明，减小粒径，导致温跃层厚度减小，放电性能变得更加稳定。在热能储存 (TES) 方面，矿渣卵石作为填充材料比石英岩更有效。研究结果有助于填充床温跃层储罐的设计和优化。放电功率和温跃层厚度均增加。结果还表明，减小粒径，导致温跃层厚度减小，放电性能变得更加稳定。在热能储存 (TES) 方面，矿渣卵石作为填充材料比石英岩更有效。研究结果有助于填充床温跃层储罐的设计和优化。