Abstract The basic absorption thermal energy storage cycle suffers from low energy storage efficiency and density, while the conventional H2O/salt working fluids risk crystallization problems. To achieve crystallization-free thermal batteries with improved energy storage performance, a hybrid compression-assisted absorption thermal energy storage cycle using H2O/1,3-dimethylimidazolium dimethylphosphate is proposed. The fluid property is modeled using non-random two liquid equations and the hybrid cycle is modeled using heat/mass transfer/conservation equations; both models are validated against measurement data with good accuracies. The effect of pressure ratio on the transient behaviors and energy storage density/efficiency is investigated to characterize the performance enhancement. Besides, different hybrid cycles are compared with the basic cycle to identify the best-performing thermal battery. Results show that, with both generation and absorption enhancement, the concentration difference is significantly enlarged from 0.230 to 0.480 by the hybrid cycle with a pressure ratio of 2.0. Meanwhile, with energy storage efficiencies maintained at 0.715–0.794, the energy storage density is effectively increased from 110.3 to 199.2 kWh/m3. Through valve switching, three hybrid cycles are realized, i.e., hybrid cycle with charging/discharging compression, hybrid cycle with charging compression, and hybrid cycle with discharging compression. Comparisons indicate that the hybrid cycle with discharging compression is the most energy-efficient, with the highest energy storage efficiency of 0.816, compared to 0.794 of the hybrid cycle with charging/discharging compression and 0.790 of the hybrid cycle with charging compression. In terms of energy storage density, the hybrid cycle with discharging compression performs quite close to the hybrid cycle with charging/discharging compression, only slightly lower by 1.6–4.3%. However, compared to the hybrid cycle with charging compression, the energy storage density of the hybrid cycle with discharging compression is significantly enhanced by 11.4–52.0%. In summary, the hybrid cycle with discharging compression is the best cycle comprehensively considering the energy storage efficiency and density. This study aims to provide theoretical supports and suggestions for the development of advanced thermal battery cycles.

中文翻译：

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H2O/1,3-二甲基咪唑鎓二甲基磷酸酯混合吸收式热电池动态性能对比

摘要 基本吸收式热能储存循环的储能效率和密度较低，而传统的H2O/盐工质存在结晶问题。为了实现具有改进储能性能的无结晶热电池，提出了一种使用 H2O/1,3-二甲基咪唑鎓二甲基磷酸酯的混合压缩辅助吸收热储能循环。流体性质使用非随机的两液体方程建模，混合循环使用传热/传质/守恒方程建模；两种模型都根据测量数据进行了验证，具有良好的准确性。研究了压力比对瞬态行为和能量存储密度/效率的影响，以表征性能增强。除了，将不同的混合循环与基本循环进行比较，以确定性能最佳的热电池。结果表明，随着发电和吸收的增强，压力比为2.0的混合循环使浓度差从0.230显着扩大到0.480。同时，在储能效率保持在0.715-0.794的情况下，储能密度有效地从110.3提高到199.2 kWh/m3。通过阀门切换，实现了三种混合循环，即带充放电压缩的混合循环、带充电压缩的混合循环和带放电压缩的混合循环。比较表明，与0.816相比，具有放电压缩的混合循环是最节能的，具有最高的储能效率为0.816。带充电/放电压缩的混合循环的 794 和带充电压缩的混合循环的 0.790。在储能密度方面，放电压缩的混合动力循环与充电/放电压缩的混合循环表现非常接近，仅略低1.6-4.3%。然而，与充电压缩混合循环相比，放电压缩混合循环的储能密度显着提高了11.4-52.0%。综上所述，放电压缩混合动力循环是综合考虑储能效率和密度的最佳循环。本研究旨在为先进热电池循环的发展提供理论支持和建议。在储能密度方面，放电压缩混合动力循环的性能与充电/放电压缩混合循环非常接近，仅略低1.6-4.3%。然而，与充电压缩混合循环相比，放电压缩混合循环的储能密度显着提高了11.4-52.0%。综上所述，放电压缩混合动力循环是综合考虑储能效率和密度的最佳循环。本研究旨在为先进热电池循环的发展提供理论支持和建议。在储能密度方面，放电压缩混合动力循环的性能与充电/放电压缩混合循环非常接近，仅略低1.6-4.3%。然而，与充电压缩混合循环相比，放电压缩混合循环的储能密度显着提高了11.4-52.0%。综上所述，放电压缩混合动力循环是综合考虑储能效率和密度的最佳循环。本研究旨在为先进热电池循环的发展提供理论支持和建议。与充电压缩混合循环相比，放电压缩混合循环的储能密度显着提高了11.4-52.0%。综上所述，放电压缩混合动力循环是综合考虑储能效率和密度的最佳循环。本研究旨在为先进热电池循环的发展提供理论支持和建议。与充电压缩混合循环相比，放电压缩混合循环的储能密度显着提高了11.4-52.0%。综上所述，放电压缩混合动力循环是综合考虑储能效率和密度的最佳循环。本研究旨在为先进热电池循环的发展提供理论支持和建议。