Dimethyl ether enrichment effects on the characteristics and emissions of biogas laminar diffusion flame

Biogas is a sustainable energy source that contributes to the closed carbon cycle by reducing greenhouse gas emissions. Nevertheless, concerns exist over its emissions, NO, and CO. This study investigates the potential of blending biogas with dimethyl ether (DME), an eco-friendly fuel, to enhance combustion characteristics and reduce emissions. Numerical analysis was conducted on DME/biogas blends (30%–60%) in a laminar diffusion flame under atmospheric pressure, considering the chemical effects of CO 2 in biogas. The addition of DME expands the reaction zone and flame thickness, increasing fuel consumption. Adding DME slightly increases the NO emission index, at a rate of 0.02 (g-NO / kg-fuel) per 10% DME increment. It significantly reduces the CO emission index, which decreases by 16–20 (g-CO / kg-fuel). 50:50 DME/biogas blend provides the optimal trade-off between NO and CO emissions. The analysis reveals that the NNH and thermal routes are the dominant contributors to NO production, and their influence increases upon DME addition. The N 2 O and prompt routes have minimal impact. Adding DME improves NO consumption through the Ch i -reburning sub-pathway, involving HCCO and CH i=1–3 radicals, partially compensating for the increase in thermal and NNH routes / NOx. More DME reduces CO production by inhibiting the forward reaction HCO + M => H + CO + M.