Catalytic oxidation process data at different pressures pertaining to the coupling of exothermic and endothermic reactions in adiabatic microchannel reactors
Description
The catalytic oxidation process data at different pressures are obtained for the coupling of exothermic and endothermic reactions in adiabatic microchannel 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. Such a reactor system is typically adiabatic in nature, meaning no heat is added in addition to the exothermic reaction heat release. The reactor system offers relatively simple designs and operation. The reactor system is in the form of a catalytic coating on a substrate composed of ceramic or metal walls defining straight reforming or oxidation channels which are parallel to each other and to the axis of the reactor. Relatively high mass transfer is provided by using high cell density channels, namely low hydraulic diameter channels. The design increases the number of boundary layers between a fluid and a reactor wall by a factor of one hundred or more, and boundary layers are known to impede heat transfer. However, relatively high heat transfer is provided. 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 is applied to the problem involving surface chemistry. The first type is a species in the gas phase above the surface. A surface species is defined to be the chemical species at the gas-solid interface. A surface does not necessarily have to be flat, and each surface species occupies one surface site. A site is considered to be a position or location on the surface at which a species can reside. A site does not necessarily have a composition itself or have to be a particular atom, and the total number of sites per unit area is conserved. Therefore, the sum of the site fractions of the species on the sites is unity. The contribution of homogeneous chemical reactions involving gas-phase species is insignificant under the conditions of interest. Contributor: Junjie Chen, E-mail address: koncjj@gmail.com, 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
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ANSYS FLUENT handles thermodynamic properties, transport properties, equation-of-state, and chemical kinetics. Boundary conditions are specified and physical properties are defined for the fluids, solids, and mixtures. Physical properties depend on temperature and composition. The governing equations are discretized in space, and the under-relaxation factors are reduced for all variables.