Comparison of conventional and metal fiber burners in a compact methane reformer using CFD modeling

Abstract

Compact reformers can be used to produce hydrogen for fuel-cell automobiles. The heat of the mehane seam reforming reaction is provided by methane burning. Generally, conventional burners have been used in combustion chambers. The Computational Fluid Dynamic (CFD) approach was used for the comparison of conventional burners with metal fiber burners and their locations for the first time. The rate of steam reforming reactions and methane combustion reactions were introduced to the CFD model and the Finite Rate/Eddy Dissipation model was used for reactions on the reforming and combustion sections. After validation of the compact reformer results by available experimental data, metal fiber was modeled using the porous-jump interior boundary condition. The results show that the best burner position for the metal fiber is the Bottom (near the catalyst) and for the conventional burner is the Top (far from the catalyst). The results show that the conventional burner in both the Middle and Bottom positions leads to an increase in the reaction zone temperature above 1200 K, which is higher than the catalyst tolerance, but placing a simple burner on the Top of the reactor does not have an out-of-range temperature problem. The hydrogen mass yield for a conventional burner at the Top position is 27.75% relative to methane. Due to the thermal uniformity in the metal fiber burner, the temperature does not exceed the catalyst limitation in the three positions (Top, Middle, and Bottom). The metal fiber burner at the Bottom of the combustion chamber shows the best performance with a hydrogen mass yield of 40.82%. The results indicate that metal fiber burners can distribute the flame more uniformly than conventional burners and increase the available heat for the reformer side.