Abstract An asymmetric two-stage sodium thermal electrochemical converter and its optimum performance are studied by means of an improved analytical model including the main losses in the overall system. Based on the study of a single-stage sodium thermal electrochemical converter, the inner process is divided into two stages including one at the 1300 K temperature (evaporator) and the other at the 800–1300 K intermediate temperature with the aim of improving efficiency. The parametric optimum selection criteria of a few main parameters of the two-stage device are provided and the coupling of the separate stages in an overall optimum system in terms of the appropriate intermediate temperature is particularly stressed. The maximum efficiency of the proposed overall system can attain 36.2%, which is 17.5% higher than that of the best performing single-stage device, and increase up to 34.1% and 24.8% over the existing two-stage devices designed by two research groups, respectively. The Pareto front obtained from numerical multiobjective and multiparametric methods endorses previous findings and visually presents the space of the states and the energetic properties of the overall arrangement compared with the corresponding data for the isolated first and second stages.

中文翻译：

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两级钠热电化学转换器：参数优化和性能增强

摘要 采用改进的分析模型，包括整个系统的主要损耗，研究了不对称两级钠热电化学转换器及其最佳性能。基于对单级钠热电化学转化器的研究，将内部过程分为两个阶段，一个在1300 K温度（蒸发器），另一个在800-1300 K中间温度，以提高效率。给出了两级装置的几个主要参数的参数优化选择标准，并特别强调了在合适的中间温度方面各个级在整体优化系统中的耦合。建议的整个系统的最大效率可以达到 36.2%，即 17。比性能最好的单级装置提高5%，比两个研究组设计的现有两级装置分别提高34.1%和24.8%。从数值多目标和多参数方法获得的帕累托前沿支持先前的发现，并与孤立的第一和第二阶段的相应数据相比，直观地展示了状态空间和整体排列的能量特性。