A consistent and computationally efficient CFD modeling framework for industrial-scale steam-methane reforming

A two-dimensional axisymmetric CFD model of an industrial steam methane reformer (SMR) tube subjected to an imposed heat flux is developed to systematically assess the influence of key modeling choices on reactor-scale predictions. Addressing inconsistencies in the literature, the study evaluates the effects of model dimensionality, reaction kinetics, mass-diffusion formulation, catalyst effectiveness treatment, gas–solid heat-transfer assumptions using local thermal equilibrium (LTE) and local non-thermal equilibrium (LNTE) models, and the inclusion of radiative heat transfer within a pseudo-homogeneous framework suitable for industrial application. The results show that the 2D axisymmetric model reliably reproduces three-dimensional predictions at significantly reduced computational cost. Differences between the Xu–Froment and Hou–Hughes kinetic models lead to only minor variations in outlet composition and temperature, while reactor performance is largely insensitive to the choice of molecular diffusion model due to turbulence-dominated transport. Assuming a constant catalyst effectiveness factor overpredicts reforming activity, whereas a variable effectiveness formulation more accurately captures diffusion-limited behavior. LTNE effects are confined mainly to the reactor inlet, confirming the adequacy of LTE assumptions for predicting overall reactor performance, and radiative heat transfer is found to have a negligible impact under the investigated industrial conditions. A parametric analysis shows that lower inlet mass flow rates, moderate steam-to-methane ratios (around 3), lower outlet pressures, and adequately distributed heat fluxes favor higher methane conversion, while variations in inlet gas composition strongly influence reforming through reaction coupling: CO-rich feeds enhance conversion via forward water–gas shift coupling, CO₂-rich feeds improve conversion by reducing hydrogen inhibition, whereas H₂-rich feeds suppress reforming due to strong kinetic and thermodynamic inhibition. Overall, the study establishes a consistent and computationally efficient pseudo-homogeneous modeling framework suitable for industrial SMR applications.