Long-term electricity storage technology is essential to achieve a high proportion utilization of fluctuating renewable energy. Carnot battery is an emerging long-term electricity storage technology with lower cost, larger capacity, and no geography restrictions. Using organic Rankine cycle (ORC) as the power unit is beneficial to integrate the low-grade waste heat, achieving a higher energy efficiency for Carnot battery. Heat storage temperature is a key parameter influencing the optimization and performance of ORC-based Carnot battery, but its optimal selection is affected by working fluid type and heat source temperature. For various application scenarios, the optimal heat storage temperatures and the highest power-to-power efficiencies of ORC-based Carnot battery are still unclear. This paper focuses on the ORC-based Carnot battery with various heat source temperatures and working fluid types. Influences of heat storage temperature on the optimization and performance of system are analyzed. Optimal heat storage temperature and the highest power-to-power efficiency at various application scenarios are given. Exergy performance characteristics of ORC-based Carnot battery are revealed, and its energy efficiency superiority is evaluated. Results indicate that the effects of heat storage temperature on system performance differ remarkably for using various working fluid types. The heat source temperature greatly affects the optimal heat storage temperature when it exceeds 60 °C. Exergy loss of system is mainly distributed in heat exchange processes, accounting for 69.4 % of the total exergy loss. The highest power-to-power efficiency of ORC-based Carnot battery can reach 1.09, exceeding the energy efficiency of combining battery and single ORC system.

中文翻译：

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ORC基卡诺电池在不同应用场景下的最佳储热温度和性能


长期储电技术对于实现波动性可再生能源的高比例利用至关重要。卡诺电池是一种新兴的长期电力储存技术，成本更低、容量更大、不受地域限制。采用有机朗肯循环（ORC）作为动力单元有利于整合低品位废热，实现卡诺电池更高的能源效率。储热温度是影响ORC基卡诺电池优化和性能的关键参数，但其优化选择受到工质类型和热源温度的影响。对于各种应用场景，基于ORC的卡诺电池的最佳储热温度和最高功率效率仍不清楚。本文重点研究具有各种热源温度和工作流体类型的基于 ORC 的卡诺电池。分析了蓄热温度对系统优化和性能的影响。给出了各种应用场景下的最佳蓄热温度和最高功率效率。揭示了基于ORC的卡诺电池的火用性能特征，并评估了其能效优势。结果表明，对于使用不同类型的工质，储热温度对系统性能的影响存在显着差异。当热源温度超过60℃时，对最佳蓄热温度影响较大。系统火用损失主要分布在热交换过程中，占总火用损失的69.4%。基于ORC的卡诺电池的最高功率效率可达1.09，超过了电池与单一ORC系统组合的能效。