Effect of flow velocity on the dimensionless Nusselt number of continuous flow reactors configured with segmented steam reforming catalyst layers
Description
The dimensionless Nusselt number data are presented to illustrate the effect of flow velocity on the heat transfer operation of continuous flow reactors configured with segmented steam reforming catalyst layers. In fluid dynamics, the dimensionless Nusselt number is the ratio of convective to conductive heat transfer at a boundary in a fluid. Convection includes both advection and diffusion. The conductive component is measured under the same conditions as the convective but for a hypothetically motionless fluid. The Nusselt number is a dimensionless number, closely related to the fluid's Rayleigh number. The mass transfer analogue of the Nusselt number is the Sherwood number. The dimensionless Nusselt number is the ratio of convective to conductive heat transfer across a boundary. The convection and conduction heat flows are parallel to each other and to the surface normal of the boundary surface, and are all perpendicular to the mean fluid flow in the simple case. An understanding of convection boundary layers is necessary to understanding convective heat transfer between a surface and a fluid flowing past it. A thermal boundary layer develops if the fluid free stream temperature and the surface temperatures differ. A temperature profile exists due to the energy exchange resulting from this temperature difference. The continuous flow reactor is configured for simultaneous oxidation and steam reformation of methanol. The channels are 0.7 millimeters in height and in width and 30.0 millimeters in length. 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 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 continuous flow 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 continuous flow reactor by giving the gas velocity. 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: 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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Steps to reproduce
The exothermic process is modeled by a chemical kinetic model. Additionally, the endothermic process is modeled in such a way as to take into account methanol steam reforming and decomposition and the water-gas shift reaction using another chemical kinetic model. To obtain the solution of the problem, numerical simulations are performed using fluid mechanics.