Effect of the use of methanol, toluene and nitromethane mixtures as fuel additives in a gasoline engine on engine performance and exhaust emissions

The increasing concerns about environmental sustainability and the depletion of fossil fuels have led to increased research into alternative fuel blends that can improve engine performance while reducing harmful emissions. This study investigates the effects of various fuel blends (methanol, toluene, and nitromethane) added to gasoline in a single-cylinder, four-stroke gasoline engine. The aim is to analyze the effects on key engine performance parameters, including thermal efficiency, brake-specific fuel consumption (BSFC), exhaust gas temperature and emissions such as carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NOx) and carbon dioxide (CO2). It was observed that the highest gain in BSFC value was achieved with a 9.70 % decrease in the tests conducted with G90M10 fuel compared to G100 under full load conditions, and accordingly, the highest gain in BTE value was achieved with a 17.14 % increase in the tests conducted with G90M10 fuel. When BSFC and BTE data are examined, it is determined that the highest positive effect compared to G100 is provided by G90M10 fuel, followed by G90M5N5 and G90T5N5 fuel mixtures, respectively. It is determined that the G90T5N5 fuel mixture provides the highest reduction in HC and CO emissions compared to G100 at full load conditions, with reductions of 56.8 % and 60.92 %, respectively. However, it is observed that the same fuel mixture increases NOx emissions by 102.53 % compared to G100 for the same conditions. The results show that lambda values (air-fuel ratio) increase with engine load in all fuel types and have a mixture closer to the stoichiometric ratio at higher loads, increasing fuel efficiency, reducing CO and HC emissions, and increasing combustion temperatures and NOx formation. The study results reveal that fuel compositions must be carefully optimized to balance performance gains with environmental impact.