A continuum model for heat and mass transfer in moving-bed reactors for thermochemical energy storage
A continuum model for heat and mass transfer in moving-bed reactors for thermochemical energy storage
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DOI：
10.1016/j.apenergy.2022.118842
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发表时间：
2022-05
期刊：
影响因子：
11.2
通讯作者：
David Korba;Wei Huang;K. Randhir;J. Petrasch;J. Klausner;Nick AuYeung;Like Li
中科院分区：
文献类型：
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作者：
David Korba;Wei Huang;K. Randhir;J. Petrasch;J. Klausner;Nick AuYeung;Like Li
在这项工作中，为固定填充床和逆流移动床反应器开发了耦合传输现象和高温热化学反应的连续传热传质模型。在提出一般建模框架后，我们重点关注该模型的二维轴对称版本，并使用文献中用于锰铁氧化物还原/氧化的填充床反应器和用于镁锰氧化物还原高达 1450°C 的内部逆流移动床反应器的实验结果进行验证。瞬态模拟结果包括气体/固体温度的局部分布、氧气浓度和反应程度，以及各种能量流分量和能量转换效率。基于二维轴对称模型的结果也与之前的一维模型获得的结果进行了比较。比较表明，捕获径向变化对于反应堆建模至关重要，并且二维结果表明与实验的一致性得到了改善。具体而言，沿径向观察到较大的温度变化，特别是在反应区中；这种不均匀的径向温度分布由于其对温度的强烈依赖性而对化学反应程度产生显着影响；与一维模型相比，二维模型中反应器出口处的总氧浓度和预测的系统效率略低。目前的传热传质模型可以为反应器设计、放大和操作条件选择提供有价值的见解，以最大限度地提高系统能量存储效率。
In this work, a continuum heat and mass transfer model coupling transport phenomena and high-temperature thermochemical reactions is developed for stationary packed-bed and counter-flow moving-bed reactors. After presenting the general modeling framework, we focus on the 2D axisymmetric version of the model for which validation is conducted with experimental results for a packed-bed reactor in the literature for manganese-iron oxide reduction/oxidation and an in-house counter-flow moving-bed reactor for magnesium-manganese oxide reduction up to 1450 °C. Transient simulation results including the local distributions of gas/solid temperatures, oxygen concentration and the extent of reaction, as well as the various energy flow components and energy conversion efficiencies are reported. The results based on the 2D axisymmetric model are also compared with those obtained from a previous 1D model. The comparison shows that capturing the radial variation is critical in reactor modeling and the 2D results demonstrate improved agreement with experiments. Specifically, large temperature variations along the radial direction are observed especially in the reaction zone; this non-uniform radial temperature distribution has a significant effect on the chemical reaction extent due to its strong dependence on temperature; and the overall oxygen concentration at the reactor exit and the predicted system efficiency are slightly lower in the 2D model compared to the 1D model. The present heat and mass transfer model can provide valuable insights into reactor design, scale-up, and operating conditions selection to maximize system energy storage efficiency.