Abstract

The quantification of the temperature difference between gas and solid phases and chemical structures at the flame front in a porous media burner is a challenging task. The present study explores the thermal behavior and pollutant formation in porous media burners (PMBs) using methane-hydrogen blends. The experimental and numerical analysis focuses on the internal temperatures of the solid and gas phases, assessing local thermal nonequilibrium under upstream and downstream combustion wave conditions. Hydrogen enrichment is found to reduce the temperature in both phases, increase the velocity and thickness of the combustion front. A linear relation between the temperature difference between both phases at the flame front and the equivalence ratio. Pollutant emissions were measured experimentally, registering a reduction in NOx emissions and an increase in CO, as hydrogen is added. Across the burner, NO, NO2, and N2O reaction pathway analyses showed that NO is formed mainly through the N and HNO pathway in the combustion front, with secondary contributions from NO2, NNH, and NH. With H2 enrichment, the N-flux for NO reduction decreases by 42%. NO formed in the flame zone remained unconsumed. Numerical simulations of NOx emissions show good agreement with experimental data.