Numerical analysis of ethanol reforming-gas effects on performance and emissions of a compression combustion engine

Internal combustion engines power more than 99.9% of vehicles currently in operation. When compared with spark ignition (SI) engines, compression ignition (CI) engines exhibit higher efficiency, improved fuel economy, and lower carbon dioxide (CO 2 ) emissions. However, CI engines typically emit higher levels of nitrogen oxides (NOx). One promising strategy to reduce emissions from CI engines is the addition of hydrogen (H 2 ) to the combustion process. This study evaluated the effects of incorporating ethanol reforming-gases on the performance and emissions of a diesel engine. Different ethanol/steam ratios and reforming temperatures were investigated, producing varying hydrogen and inert gas fractions. The analyses show that increasing the substitution ratio led to higher in cylinder pressure levels at low and intermediate loads. With a 40% substitution of diesel by reforming gas, a significant reduction in specific fuel consumption (37.1% at 20 kW and 33.7% at 30 kW) and CO 2 emissions (13.4% and 11.4%, respectively) was observed. NO emissions were also drastically reduced (32.0% at 20 kW and 54.4% at 30 kW). Dual-fuel combustion resulted in heat release rate peaks up to twice as high, due to a longer ignition delay. Total hydrocarbon (THC) emissions showed variable behavior, with a notable reduction of 23.7% (20 kW) and 27.6% (30 kW) at the highest substitution levels. • CFD model validated with pressure errors below 7% for B12 diesel–ethanol reformate. • B12 diesel achieved 40% energy substitution using ethanol reforming-gas. • ISFC with B12 diesel fell 37.1% at 20 kW and 33.7% at 30 kW with reformate. • CO 2 and NO emissions dropped up to 13.4% and 54.4% using ethanol reformate. • Ethanol reformate shows strong potential for cleaner and efficient CI engines.