2/2026
Emissions evaluation of a diesel engine fueled by a water-diesel emulsion
Water–diesel (W/D) emulsions have emerged as a promising for reducing harmful exhaust emissions while maintaining diesel engine performance, particularly emissions of nitrogen oxides (NOx) and smoke opacity (SO). This study investigated the effects of two (W/D) emulsion ratios containing 7% and 17% water by volume on the exhaust emissions of a water-cooled, 4-cylinder, direct-injection diesel engine operating at a constant speed of 1600 rpm under various load conditions. The experimental results demonstrated that the 7% (W/D) emulsion reduced NOx and SO emissions by 27% and 82%, respectively, compared with neat diesel fuel. The 17% (W/D) emulsion achieved greater reductions, lowering NOx and SO emissions by 38% and 89%, respectively. Nevertheless, both emulsions increased emissions of carbon monoxide (CO), carbon dioxide (CO₂), and unburned hydrocarbons (HC). For the 7% emulsion, CO, CO₂, and HC emissions increased by 20%, 8%, and 30%, respectively, whereas the corresponding increases for the 17% emulsion were 33%, 24%, and 50%. Overall, although the 17% (W/D) emulsion provided superior reductions in NOx and SO emissions, the 7% W/D emulsion offered a more favorable compromise between the reduction of regulated pollutants and the increase in other exhaust emissions under the investigated operating conditions.