Enhancing Hydrogen Production in a Porous Reactor for the Steam Methane Reforming: Optimizing Operating Parameters and Radiation Heat Transfer Mechanism

The effects of operating parameters and radiation heat transfer mechanism on the performance of a porous catalytic reactor for hydrogen production by steam methane reforming (SMR) were investigated numerically. User-defined functions written in C++ were developed, coupled, and hooked to the ANSYS FLUENT software for calculating the reaction kinetics rates of the SMR. The methane conversion ratio increased from 13.34% to 72.28% at a steam-to-carbon (S/C) ratio of 2 when the temperature was raised from 773 K to 1073 K, respectively. Increasing the S/C ratio from 2 to 5 improved the methane conversion ratio from 13.34% to 24.91% at a temperature of 773 K, respectively. A higher S/C ratio introduces more steam, stimulating the water–gas shift reaction, which generates additional H₂ and CO₂. Decreasing the gas hourly space velocity (GHSV) from 30,000 h⁻¹ to 5000 h⁻¹ increased the methane conversion ratio from 57.75% to 61.06%. Compared to the P-1 and Rosseland models, the discrete ordinates radiation model better agrees with the experimental data and better tackles the heat transfer within the porous media inside the SMR reactor. The highest methane conversion ratio of 98.15% was achieved at 5 bar pressure, 1073 K temperature, S/C ratio of 5, and 5000 h⁻¹ GHSV.