Dimensionless Nusselt number data associated with the steam reforming catalyst segmentation methods employed for microchannel steam reforming reactors

The dimensionless Nusselt number data are presented associated with the steam reforming catalyst segmentation methods employed for microchannel steam reforming reactors. The reforming process proceeds in one set of the channels through which the endothermic reactants flow, and the exothermic oxidation process proceeds in the second set of the channels. Exothermic and endothermic reactions take place simultaneously whereby the heat required for the latter is supplied by the former. Heat transfer occurs via conduction through the walls of the reactor. For the endothermic reaction, the structure is especially effective because both the internal surfaces of the walls are coated with structured catalysts, which is capable of providing more efficient heat exchange and minimizing the problem of loss of catalytic activity. The channels are 0.7 millimeters in height and in width and 30.0 millimeters in length. Channel height refers to the inside height of a channel. To ensure the mechanical strength at elevated pressures, the thickness of the uncoated walls and the catalyst layers is 0.7 millimeters and 0.1 millimeters, respectively. The oxidation catalyst consists essentially of oxides of copper, zinc and aluminum. The oxidation catalyst allows for initial start-up and the heat-up of the reactor system. The reforming catalyst consists essentially of copper and oxides of zinc and aluminum. The exothermic and endothermic processes are conducted at a pressure of 0.8 megapascals, with a methanol-air equivalence ratio of 0.8 and a steam-to-methanol molar ratio of 1.17. The inlet temperature of the mixtures is 373 degrees Kelvin. The temperature of the reactor can be regulated by the balance of the flow rates so that the catalyst is not overheated by the exothermic process. To assure that adequate temperatures are provided for endothermic reforming, operating flow conditions are specified for the reactor by giving the gas velocity. The gas velocity is 2.0 meters per second at the reforming channel inlets and 0.6 meters per second at the oxidation channel inlets, thereby assuring sufficient heat in the reactor to carry out endothermic reforming of methanol. 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 each reforming channel, the catalyst layer is reduced by half in amount. The catalyst segments have a uniform distribution of length, and the spacing between catalyst segments is equal to their length. 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

本数据集提供了微通道蒸汽重整反应器所用蒸汽重整催化剂分段方案对应的无量纲努塞尔数（dimensionless Nusselt number）数据。重整反应在一组通道内进行，该通道输送吸热反应物；而放热氧化反应则在另一组通道内开展。放热与吸热反应同步进行，前者为后者提供所需热量。热量通过反应器壁面的传导实现传递。针对吸热反应，该结构尤为高效：反应器壁的两侧内表面均涂布结构化催化剂，可实现更高效的热交换，并最大限度降低催化活性流失问题。通道的高与宽均为0.7毫米，长度为30.0毫米；通道高度指通道内部的净高。为保证高压工况下的机械强度，未涂布壁面与催化剂层的厚度分别为0.7毫米与0.1毫米。氧化催化剂主要由铜、锌与铝的氧化物组成，可用于反应器系统的初始启动与升温过程。重整催化剂主要由铜以及锌、铝的氧化物组成。放热与吸热反应的运行工况为：压力0.8兆帕，甲醇-空气当量比0.8，蒸汽与甲醇的摩尔比1.17。进料混合物的入口温度为373开尔文。可通过流量平衡调节反应器温度，避免催化剂因放热反应而过热。为确保吸热重整反应所需的足够温度，本数据集通过给出气体流速来规定反应器的运行工况：重整通道入口处的气体流速为2.0米每秒，氧化通道入口处为0.6米每秒，以此保证反应器内具备足够热量以完成甲醇的吸热重整反应。边界条件将催化活性表面的宏观流体流动与表面反应速率相关联；催化活性表面的多相反应会影响该表面的热与质量平衡。每个重整通道内的催化剂负载量减半；催化剂分段的长度分布均匀，且分段间距等于分段自身的长度。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，中国河南焦作世纪大道2000号，454000，中华人民共和国