Methanol mole fraction data pertaining to the effect of porosity on the steam-methanol reforming process in microchannel reactors

The methanol mole fraction data are obtained for illustrating the effect of porosity on the steam-methanol reforming process in microchannel reactors. Porosity or void fraction is a measure of the void spaces in a material, and is a fraction of the volume of voids over the total volume. In gas-liquid two-phase flow, the void fraction is defined as the fraction of the flow-channel volume that is occupied by the gas phase or, alternatively, as the fraction of the cross-sectional area of the channel that is occupied by the gas phase. The autothermal reactor is configured for simultaneous oxidation and steam reformation of methanol. Water steam is converted into hydrogen-rich gas using methanol in an endothermic reaction on a catalyst. The energy which is released during catalytic oxidation is necessary for the endothermic steam reformation taking place simultaneously. Methanol is combusted catalytically with air, and the heat released is used to heat the reactor. There is even less need for mass and volume storage capacity, since the same alcohol fuel is used for the endothermic and exothermic processes. An array of channels operating in parallel is used, and the inside of the channels is coated. All channels are of the same cross-section and length. Additionally, there are equal numbers of oxidation and reforming channels, which are arranged in an alternating pattern. The wall of each channel is composed of a substrate coated with a catalyst. The substrate is preferably metal, and most preferably stainless-steel sheet. To facilitate computational modeling of transport phenomena and chemical kinetics in the flowing system of complex chemical reactions involving gas-phase and surface species, steady-state analyses are performed and computational fluid dynamics is used. ANSYS FLUENT handles thermodynamic properties, transport properties, and chemical kinetics. The contribution of homogeneous chemical reactions involving gas-phase species is insignificant under the conditions of interest. The boundary conditions relate macroscopic fluid flow at a catalytically active surface to the rates of surface reactions. Heterogeneous reactions at a catalytically active surface affect the heat and mass balance at the surface. In addition, surface reactions create sources and sinks of chemical species on the surface and in the gas phase. Consequently, chemical reactions involving surface species significantly influence the boundary conditions. The mass fluxes of gas-phase species at the phase boundaries are balanced by the production rates of gas-phase species by surface reactions.
Contributor: Junjie Chen, E-mail address: [e-mail], ORCID: 0000-0002-5022-6863, Department of Energy and Power Engineering, School of Mechanical and Power Engineering, Henan Polytechnic University, 2000 Century Avenue, Jiaozuo, Henan, 454000, P.R. China

本数据集提供甲醇摩尔分数数据，用于阐明孔隙率（Porosity）对微通道反应器内蒸汽-甲醇重整工艺的影响。孔隙率（或空隙率（void fraction））是表征材料内部空隙空间的参数，定义为空隙体积与总体积的比值。在气液两相流（gas-liquid two-phase flow）中，空隙率指流道体积中气相所占的份额，或流道横截面积中气相所占的份额。
本研究所用的自热反应器可同时实现甲醇的氧化反应与蒸汽重整反应：在催化剂作用下，甲醇通过吸热反应与水蒸气反应生成富氢气体；而催化氧化过程释放的热量，恰好为同步进行的吸热蒸汽重整反应提供所需能量。甲醇可与空气发生催化燃烧反应，释放的热量用于加热反应器。由于吸热与放热过程采用同一种醇类燃料，显著减少了系统对质量与体积存储容量的需求。
该装置采用平行并联的通道阵列，通道内壁涂覆有催化涂层。所有通道的横截面与长度均保持一致，且氧化通道与重整通道数量相等，呈交替排布模式。每个通道的壁面由涂覆催化剂的基底构成，基底优选金属材质，最优为不锈钢薄板。
为对包含气相与表面物种的复杂化学反应流动系统开展输运现象与化学动力学的计算建模，本研究采用稳态分析方法，并借助计算流体动力学（Computational Fluid Dynamics）工具。ANSYS FLUENT可处理热力学性质、输运性质与化学动力学相关计算。在目标工况下，气相物种参与的均相化学反应的贡献可忽略不计。
催化活性表面处的宏观流体流动与表面反应速率相关联，构成边界条件。催化活性表面处的多相反应会影响表面的热质平衡；同时，表面反应会在表面及气相中形成化学物种的源与汇。因此，涉及表面物种的化学反应会对边界条件产生显著影响。相界面处的气相物种质量通量，与表面反应生成的气相物种速率保持平衡。
贡献者：陈俊杰，电子邮箱：[e-mail]，ORCID：0000-0002-5022-6863，河南理工大学机械与动力工程学院能源与动力工程系，河南省焦作市世纪大道2000号，454000，中华人民共和国