SOFC内CH4-H2O重整反应及其影响因素数值分析

Numerical analysis of CH4-H2O reforming reaction in SOFC and its influencing factors

为研究CH4-H2O在镍基阳极固体氧化物燃料电池(SOFC)的传质传热、催化重整与电化学反应的关系,构建了一种单通道板式SOFC三维数值模型,模型耦合了质量、动量、能量、电荷传递以及CH4-H2O重整反应动力学,对操作温度、水碳比(S/C)、特别是电流密度(J)等影响因素进行分析并通过实验验证了模型的有效性。结果表明,CH4-H2O重整反应速率随温度变化明显;当J=0.6 A/cm^2时,操作温度高于750℃,S/C在3~3.5左右可防止直接CH4-H2O重整引起的热力学积碳;电流密度与CH4转化率、燃料利用率和CH4-H2O重整速率反应密切相关,当J>0.45 A/cm^2时,CH_4转化率迅速上升,但当J达到0.9 A/cm^2后,CH4转化率趋于平稳。电流密度越大,燃料利用率越高,当J=0.9 A/cm^2,燃料利用率可达73.2%;此外,电流密度有助于抑制热力学积碳。

In order to study the relationship between the catalytic reforming of CH4-H2O and the electrochemical reaction on nickel-based of SOFC,a three-dimensional numerical model of single channel panel SOFC was constructed.The functions of mass,momentum,energy,charge transfer and the reaction kinetics of CH4-H2O reforming were coupled in this model.The influencing factors such as operating temperature,steam-carbon ratio,especially current density were analyzed and the model were verified by experiments.The reaction rate of CH4-H2O reforming varies obviously with temperature.Thermodynamic carbon deposition caused by direct CH4-H2O reforming could be prevented when current density was 0.6 A/cm^2,the operating temperature was higher than 750℃and S/C was about 3-3.5.The conversion rate of CH4,fuel utilization and the reaction rate of CH4-H2O reforming were related to the current density.When current density was greater than 0.45 A/cm^2,the conversion rate of CH4 increased rapidly.However,when current density reached 0.9 A/cm^2,the conversion rate of CH4 tended to constant.The fuel utilization increased with the increased of current density,and when current density was 0.9 A/cm^2,the fuel utilization could reach 73.2%.Moreover,thermodynamic carbon deposition could be inhibited by current density.