George Ginu R, Bockelmann Marina, Schmalhorst Leonhard, Beton Didier, Gerstle Alexandra, Lindermeir Andreas, Wehinger Gregor D
Institute of Chemical and Electrochemical Process Engineering, Clausthal University of Technology, Leibnizstr. 17, 38678 Clausthal-Zellerfeld, Germany.
CUTEC Research Centre, Clausthal University of Technology, Leibnizstr. 23, 38678 Clausthal-Zellerfeld, Germany.
Materials (Basel). 2022 May 24;15(11):3754. doi: 10.3390/ma15113754.
Open-cell metallic foams used as catalyst supports exhibit excellent transport properties. In this work, a unique application of metallic foam, as pelletized catalyst in a packed bed reactor, is examined. By using a wall-segment Computational Fluid Dynamics (CFD) setup, parametric analyses are carried out to investigate the influence of foam morphologies (cell size ϕ=0.45−3 mm and porosity ε=0.55−0.95) and intrinsic conductivity on flow and heat transport characteristics in a slender packed bed (N=D/dp=6.78) made of cylindrical metallic foam pellets. The transport processes have been modeled using an extended version of conventional particle-resolved CFD, i.e., flow and energy in inter-particle spaces are fully resolved, whereas the porous-media model is used for the effective transport processes inside highly-porous foam pellets. Simulation inputs include the processing parameters relevant to Steam Methane Reforming (SMR), analyzed for low (Rep100) and high (Rep5000) flow regimes. The effect of foam morphologies on packed beds has shown that the desired requirements contradict each other, i.e., an increase in cell size and porosity favors the reduction in pressure drop, but, it reduces the heat transfer efficiency. A design study is also conducted to find the optimum foam morphology of a cylindrical foam pellet at a higher Rep~5000, which yields ϕ = 0.45, ε = 0.8. Suitable correlations to predict the friction factor and the overall heat transfer coefficient in a foam-packed bed have been presented, which consider the effect of different foam morphologies over a range of particle Reynolds number, 100≤Rep≤5000.
用作催化剂载体的开孔金属泡沫具有优异的传输性能。在这项工作中，研究了金属泡沫作为填充床反应器中造粒催化剂的独特应用。通过使用壁面分段计算流体动力学（CFD）设置，进行了参数分析，以研究泡沫形态（泡孔尺寸ϕ = 0.45 - 3毫米，孔隙率ε = 0.55 - 0.95）和本征电导率对由圆柱形金属泡沫颗粒制成的细长填充床（N = D/dp = 6.78）中流动和传热特性的影响。传输过程使用传统颗粒解析CFD的扩展版本进行建模，即颗粒间空间中的流动和能量被完全解析，而多孔介质模型用于高孔隙率泡沫颗粒内部的有效传输过程。模拟输入包括与蒸汽甲烷重整（SMR）相关的工艺参数，针对低（Rep100）和高（Rep5000）流动工况进行了分析。泡沫形态对填充床的影响表明，所需的要求相互矛盾，即泡孔尺寸和孔隙率的增加有利于压降的降低，但会降低传热效率。还进行了一项设计研究，以找到在较高Rep~5000时圆柱形泡沫颗粒的最佳泡沫形态，其结果为ϕ = 0.45，ε = 0.8。提出了适用于预测泡沫填充床中摩擦系数和总传热系数的关联式，该关联式考虑了在100≤Rep≤5000的颗粒雷诺数范围内不同泡沫形态的影响。
