Experimental and Numerical Investigation of Laminar Burning Velocities of Artificial Biogas Under Various Pressure and CO2 Concentration

As a renewable and sustainable fuel made from digestion facility, biogas is composed predominantly of methane (CH4) and carbon dioxide (CO2). CO2 in biogas strongly affects its combustion characteristics. In order to develop efficient combustors for biogas, fundamental flame characteristics of biogas require extensive investigation. In understanding the influence of CO2 concentration and mixture pressure on biogas combustion, the effects of CO2 concentration on the laminar burning velocity of methane/air mixtures were studied at different pressures. The studies were conducted using both numerical and experimental methods. The experiment was conducted using a constant volume high pressure combustion chamber. The propagating flames were
recorded with a high speed digital camera by employing Schlieren photography technique. The numerical simulation was carried by utilizing CHEMKIN-PRO with GRI-Mech 3.0 employed as the chemical kinetics model. The results show that the laminar burning velocity of methane-air mixtures decreased with an increase in CO2 concentration and mixture pressure. Therefore, the burning velocity of biogas mixtures may decrease as the amount of CO2 in the gas increases.