A comparative study of first and second generation biodiesel blends under quaternary injection strategies for enhanced engine performance and reduced emissions

Biodiesel is a promising renewable alternative fuel, offering compatibility with conventional engines without necessitating significant engine modifications. To facilitate the practical integration of biodiesel into engine systems, this study evaluates the performance of two different biodiesel blends (fatty acid methyl ester and hydrogenated catalytic) in a turbocharged inter-cooled diesel engine. The research employs quaternary injection techniques an advanced injection technique, which involve multiple injection events per cycle to enhance engine combustion and emission characterictics of the biodiesel blend fuels and comparing their performance and emission characteristics with those of conventional diesel. Results showed that fatty acid methyl ester biodiesel effectively reduced the CO, UHC, and NOx emissions at lower blend ratios (up to 10 %), with minimal impact on the brake-specific fuel consumption. Conversely, hydrogenated catalytic biodiesel demonstrates notable advantages in reducing fuel consumption with carbon monoxide and particle emissions, particularly for higher blend ratios (20 %), leading to improved indicated thermal efficiency. Additionally, an investigation on higher biodiesel blends under varying early injection timings showed that, optimal fuel efficiency was observed at an early injection timing of -43.6 degrees CA, accompanied by reductions in total particle number and unburned hydrocarbon emissions albeit with elevated carbon monoxide and nitrogen oxide emissions. These findings suggest that advanced injection strategies combined with sustainable biodiesel blends can significantly improve engine performance and reduce environmental impact, supporting the transition towards cleaner and more efficient transportation fuels.