The Experts below are selected from a list of 4623 Experts worldwide ranked by ideXlab platform

Seung Man Baek - One of the best experts on this subject based on the ideXlab platform.

  • a numerical study of the effectiveness factors of nickel Catalyst pellets used in steam methane reforming for residential fuel cell applications
    International Journal of Hydrogen Energy, 2014
    Co-Authors: Seung Man Baek, Jung Ho Kang, Kyujin Lee, Jin Hyun Nam
    Abstract:

    Abstract A numerical study is performed to evaluate the effectiveness factors of commercial nickel Catalyst pellets commonly used in small-scale steam methane reformers for residential fuel cell applications. Based on the intrinsic reaction kinetics of the steam reforming process, the standard composition of the partially reformed gas mixture is determined as a function of the methane conversion. The heterogeneous reforming reactions inside the Spherical Catalyst pellets are then modeled by considering the distributed reaction, multi-component diffusion and permeation, and conductive and convective heat transfer in the porous media. Various operating conditions, including the reforming temperature, steam-to-carbon (S/C) ratio, operating pressure, and geometrical parameters, such as the pellet diameter and mean pore size, are simulated. The effectiveness factors calculated for each condition are presented as a function of the methane conversion. Finally, simple correlations for the effectiveness factors are presented, and their accuracies are assessed.

Jin Hyun Nam - One of the best experts on this subject based on the ideXlab platform.

  • a numerical study of the effectiveness factors of nickel Catalyst pellets used in steam methane reforming for residential fuel cell applications
    International Journal of Hydrogen Energy, 2014
    Co-Authors: Seung Man Baek, Jung Ho Kang, Kyujin Lee, Jin Hyun Nam
    Abstract:

    Abstract A numerical study is performed to evaluate the effectiveness factors of commercial nickel Catalyst pellets commonly used in small-scale steam methane reformers for residential fuel cell applications. Based on the intrinsic reaction kinetics of the steam reforming process, the standard composition of the partially reformed gas mixture is determined as a function of the methane conversion. The heterogeneous reforming reactions inside the Spherical Catalyst pellets are then modeled by considering the distributed reaction, multi-component diffusion and permeation, and conductive and convective heat transfer in the porous media. Various operating conditions, including the reforming temperature, steam-to-carbon (S/C) ratio, operating pressure, and geometrical parameters, such as the pellet diameter and mean pore size, are simulated. The effectiveness factors calculated for each condition are presented as a function of the methane conversion. Finally, simple correlations for the effectiveness factors are presented, and their accuracies are assessed.

Jung Ho Kang - One of the best experts on this subject based on the ideXlab platform.

  • a numerical study of the effectiveness factors of nickel Catalyst pellets used in steam methane reforming for residential fuel cell applications
    International Journal of Hydrogen Energy, 2014
    Co-Authors: Seung Man Baek, Jung Ho Kang, Kyujin Lee, Jin Hyun Nam
    Abstract:

    Abstract A numerical study is performed to evaluate the effectiveness factors of commercial nickel Catalyst pellets commonly used in small-scale steam methane reformers for residential fuel cell applications. Based on the intrinsic reaction kinetics of the steam reforming process, the standard composition of the partially reformed gas mixture is determined as a function of the methane conversion. The heterogeneous reforming reactions inside the Spherical Catalyst pellets are then modeled by considering the distributed reaction, multi-component diffusion and permeation, and conductive and convective heat transfer in the porous media. Various operating conditions, including the reforming temperature, steam-to-carbon (S/C) ratio, operating pressure, and geometrical parameters, such as the pellet diameter and mean pore size, are simulated. The effectiveness factors calculated for each condition are presented as a function of the methane conversion. Finally, simple correlations for the effectiveness factors are presented, and their accuracies are assessed.

Anthony G Dixon - One of the best experts on this subject based on the ideXlab platform.

  • local transport and reaction rates in a fixed bed reactor tube endothermic steam methane reforming
    Chemical Engineering Science, 2017
    Co-Authors: Anthony G Dixon
    Abstract:

    Abstract Resolved-particle 3-D computational fluid dynamics (CFD) simulations are presented of endothermic steam methane reforming in a random packed bed of 807 Spherical Catalyst particles at a tube-to-particle diameter ratio of N = 5.96 with constant wall heat flux. The fluid flow field is fully coupled to the temperature and species distributions inside the particles. This enables simulation of diffusion, conduction and reaction inside the Catalyst particles, as opposed to only surface reactions. The results illustrate 3-D distributions of flow, temperature, species and reaction rates inside a 0.7 m length of packed tube. These show large variations on near-wall particle external surfaces, and non-symmetric distributions inside the Catalyst particles on cross-sections through the bed. The detailed CFD approach allows statistical analysis of the particle-to-particle reaction rate variations, the correlation of rate with location in the bed, and the intrinsic variability of radial temperature and species mass fraction profiles. Comparisons to a 1-D reactor tube heterogeneous effective medium model showed that axial profiles of cross-sectional average temperature, species and velocity could not be reproduced using particle-fluid heat and mass transfer coefficients estimated from non-reacting simulations in the same tube. Comparisons to a 2-D reactor tube heterogeneous effective medium model showed good agreement with axial profiles if radial local void fractions and axial velocities were included in the model. Improved agreement with radial temperature profiles resulted from the model with a radially-varying effective radial thermal conductivity.

  • 3d cfd simulations of steam reforming with resolved intraparticle reaction and gradients
    Chemical Engineering Science, 2007
    Co-Authors: Anthony G Dixon, Ertan M Taskin, Hugh E Stitt, Michiel Nijemeisland
    Abstract:

    Abstract Computational fluid dynamics (CFD) simulations are reported for flow, diffusion, reaction and heat transfer in a 120 ∘ segment of an N = 4 packed tube for the endothermic methane steam reforming reaction. The present work improves on previous approaches by explicit inclusion of intraparticle effects (conduction, species diffusion and reaction) coupled to realistic 3D external flow and temperature fields. It is shown that the usual assumption of symmetric species and temperature fields inside Spherical Catalyst particles holds for particles away from the tube wall, but particles placed in the strong temperature gradient near the tube wall show significant deviations.

Zhongwei Chen - One of the best experts on this subject based on the ideXlab platform.