Numerical investigation of hydrogen-blended low-calorific-value landfill gas combustion : flame stability and pollutant suppression in porous media burners

Abstract

This study investigates the combustion characteristics of hydrogen-enriched low-calorific landfill gas (LFG) in a double-layer porous media burner by using numerical simulations. The research addresses challenges related to flame instability and pollutant emissions during low-calorific LFG combustion. A two-dimensional axisymmetric numerical model was developed in ANSYS Fluent, incorporating a skeletal chemical reaction mechanism and the standard k-ε turbulence model. Simulations were performed with LFG composed of 30% methane and 70% carbon dioxide (LFG30) under varying hydrogen blending ratios (0 to 20%), an equivalence ratio of 1.5, and an inlet gas velocity of 0.15 m/s. The results demonstrate that increasing hydrogen concentrations shifts the flame upstream, lowers both combustion and exhaust gas temperatures, and significantly decreases CO and NOx emissions. When the hydrogen blending ratio reaches 20%, the mole fractions of CO and NOx at the outlet are reduced by 22.14 and 72.65%, respectively, compared with the pure LFG30. The findings indicate that hydrogen enrichment significantly enhances the combustion stability and emission performance of low-calorific LFG in porous media burners, providing an effective approach for efficiently utilizing low-calorific-value fuels even at extreme operating conditions. This study offers novel insights toward the development of effective burners aimed at increasing the utilization of this underutilized renewable energy resource and addressing environmental concerns.