Simulation study on the microscopic characteristics of electrochemical Bunsen reaction in the sulfur-iodine cycle for renewable hydrogen production
Simulation study on the microscopic characteristics of electrochemical Bunsen reaction in the sulfur-iodine cycle for renewable hydrogen production
复制标题
硫碘循环制氢电化学本生反应微观特性模拟研究
DOI：
10.1016/j.applthermaleng.2019.02.074
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发表时间：
2019
影响因子：
6.4
通讯作者：
Guomin Cui
中科院分区：
文献类型：
--
作者：
Zhi Ying;Yao Zhang;Xiaoyuan Zheng;Binlin Dou;Guomin Cui
硫-碘(SI)热化学水裂解循环是一种热效率高、污染小的制氢工艺。提出了利用电化学电池(EC)进行循环中的本森反应，并对该电池进行了研究。为了填补电化学本生反应微观特征方面的知识空白，本文进行了数值研究。建立了二维稳态层流等温电化学反应模型，详细描述了电化学反应的流动、物质转移和电极反应等过程，模拟结果与实验数据吻合较好。随着电能消耗从9.1MW/m~2增加到227.9 W/m~2，反应速率随电流密度的增加而增加，表现为物种摩尔流量的变化。升高温度会抑制物种的转化和生成。尽管较高的流速会缩短流动停留时间和物种浓度的变化，但较快的流动速度和较高的本体反应物浓度会导致整体反应速率的提高。随着流量的增加，泵浦功率的消耗也从0.264 W/m2增加到6.661 W/m2。得到了4-5 A/dm2、30 3-313 K和0.0 1-0.0 2 m/S的最佳操作条件。仿真结果有助于更好地理解EC中的现象，并进一步优化EC。
The sulfur–iodine (SI) thermochemical water-splitting cycle is a promising hydrogen production process with high thermal efficiency and low pollution. The Bunsen reaction in the cycle using an electrochemical cell (EC) has been proposed and R&D on the cell has been carried out. To fill the knowledge gap in the microscopic characteristics of the electrochemical Bunsen reaction, a numerical study was conducted in this work. A two-dimensional, steady state, laminar and isothermal model of EC with detailed processes of flow, species transfer and electrode reactions was developed, and the simulated results showed good agreement with experimental data. The reaction rates, indicated in the form of species molar flux variation, increase with rising current density due to more electron transfer at a certain time, along with the increase of electric energy consumption from 9.1 W/m2to 227.9 W/m2. Increasing the temperature inhibits the conversion and generation of species. Although higher flow rate reduces the flow residence time as well as the concentration variation of species, faster flow and higher bulk reactants concentration around the electrode surface lead to the increase of overall reaction rates. The consumption of pumping power also increases from 0.264 W/m2to 6.661 W/m2with rising flow rate. The optimal operating conditions of 4–5 A/dm2, 303–313 K and 0.01–0.02 m/s are obtained. The simulation favors a better understanding of the phenomena occurring in the EC and its further optimization.