The scientific community has taken on the challenge to develop innovative methods to exploit low-temperature (<100 °C) heat sources, having large potential to decrease the carbon footprint. In this review, we first summarise the novel proposed techniques, and then we propose a framework for comparing the performances reported in the literature based on two indices, which are currently critical for the technical and economic feasibility: energy efficiency and power density. Two techniques show the best performances; both use distillation to regenerate the working solution of a flow battery. In many papers, schemes based on additional heat exchangers are proposed with the aim of improving the efficiency. Such techniques are also discussed here: first, the power per unit surface of the heat exchangers is discussed as a performance index; then, a method for inherently ranking the techniques, independent of the use of additional heat exchangers, is provided. The analysis shows that the application of such schemes does not significantly change the ranking of the techniques, while having a detrimental effect on the complexity of the whole system. Finally, we discuss the performances of the various techniques based on general thermodynamic principles and methods; in particular, the meaning of the temperature versus entropy graph in this context is considered.

中文翻译：

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利用低温热源生产能源的创新技术：重要文献综述和热力学分析

科学界已面临开发新方法来利用低温（<100°C）热源的挑战，这具有减少碳足迹的巨大潜力。在这篇综述中，我们首先总结了提出的新颖技术，然后我们提出了一个框架，用于基于两个指标比较文献中报道的性能，这两个指标目前对于技术和经济可行性至关重要：能源效率和功率密度。两种技术表现最佳。两者都使用蒸馏来再生液流电池的工作溶液。在许多论文中，提出了基于附加热交换器的方案，以提高效率。这里还讨论了这些技术：首先，将热交换器的每单位表面的功率作为性能指标进行讨论；然后，提供了一种独立于其他热交换器的使用而对技术进行固有排名的方法。分析表明，此类方案的应用不会显着改变技术的排名，同时会对整个系统的复杂性产生不利影响。最后，我们根据通用热力学原理和方法讨论了各种技术的性能。特别是温度的含义 我们基于通用热力学原理和方法讨论了各种技术的性能；特别是温度的含义 我们基于通用热力学原理和方法讨论了各种技术的性能；特别是温度的含义相对于熵图在这种情况下被考虑。