This study performs thermodynamic optimization of solid oxide co-electrolysis cell system’s key operating parameters (current density, current-to-reactant ratio, and air ratio) by using high-fidelity and empirical-based system component models. For each operating parameter, a sensitivity analysis is conducted to elucidate optimal operating points for high system performance evaluated by indices such as system efficiency, reactant conversion, and H₂:CO ratio. At a high current density of 1.2 A/cm², the highest system efficiency of 58.21%, the highest reactant conversion of 63.84%, and the lowest H₂:CO ratio of 1.258 are obtained. Likewise, a high current-to-reactant ratio of 0.9 allows obtaining the high system efficiency of 58.26%, the high reactant conversion of 83.79%, and the lowest H₂:CO ratio of 1.230. Contrary to the two parameters, at the lowest air ratio of 3, the maximum system efficiency of 63.38% and the maximum H₂:CO ratio of 1.516 are obtained, whereas the highest reactant conversion of 62.78% is obtained at the highest air ratio. Based on the single parameter analysis, a performance map for each system performance index is derived as a function of current density and current-to-reactant ratio under the fixed air ratio given that the air ratio is more related to the thermal inertia of the stack. To gain high system efficiency and high reactant conversion, a high current-to-reactant ratio of 0.75 ∼ 0.90 is necessary. The high current density of 1.2A/cm² is also recommended for obtaining high performance, a small temperature gradient inside the SOEC stack, and small temperature variation with the change of the current-to-reactant ratio. However, if the system aims to obtain a low H₂:CO ratio, low current-to-reactant ratio and low current density are suggested at the expense of system efficiency and reactant conversion. The maximum system efficiency is obtained at 1.2A/cm² and the current-to-reactant ratio of 0.75, and the maximum reactant conversion of 88.91% is obtained at 1.2A/cm² and the current-to-reactant ratio of 0.90. On the other hand, the highest H₂:CO ratio is obtained at 0.2 A/cm² and the current-to-reactant ratio of 0.15. The extensive results for the solid oxide co-electrolysis cell system obtained in this study enable figuring out the coupling effects of key operating parameters and capturing optimal operating conditions of a solid oxide co-electrolysis cell system without performing costly experiments under various operating conditions.

本研究使用高保真和基于经验的系统组件模型，对固体氧化物共电解槽系统的关键操作参数（电流密度、电流与反应物比和空气比）进行热力学优化。对于每个操作参数，都会进行灵敏度分析，以阐明通过系统效率、反应物转化率和 H ₂ :CO 比等指标评估的高系统性能的最佳操作点。在1.2 A/cm ²的高电流密度下，系统效率最高58.21%，反应物转化率最高63.84%，H ₂最低获得 1.258 的 :CO 比。同样，0.9 的高电流与反应物比允许获得 58.26% 的高系统效率、83.79% 的高反应物转化率和 1.230的最低 H ₂ :CO 比。与这两个参数相反，在最低空气比为 3 时，系统效率最高为 63.38%，H ₂最高:CO 比为 1.516，而在最高空气比下获得 62.78% 的最高反应物转化率。在单一参数分析的基础上，考虑到空气比与电堆的热惯性更相关，在固定空气比下，每个系统性能指标的性能图作为电流密度和电流与反应物比的函数导出. 为了获得高系统效率和高反应物转化率，需要 0.75 ∼ 0.90 的高电流与反应物比。还建议使用1.2A/cm ²的高电流密度，以获得高性能、SOEC 堆栈内部的小温度梯度以及随电流与反应物比变化的小温度变化。然而，如果系统旨在获得低 H ₂:CO 比、低电流与反应物比和低电流密度的建议是以牺牲系统效率和反应物转化率为代价的。最大系统效率以1.2A /厘米获得²和0.75的电流-反应物的比例，和在1.2A /厘米得到的88.91％的最大反应物转化²和0.90电流-反应物比。另一方面，在 0.2 A/cm ^{2 时}获得最高的 H ₂ :CO 比电流与反应物之比为 0.15。本研究中获得的固体氧化物共电解槽系统的广泛结果能够确定关键操作参数的耦合效应并捕获固体氧化物共电解槽系统的最佳操作条件，而无需在各种操作条件下进行昂贵的实验。