Exergy, energy, performance, and combustion analysis for biodiesel NOx reduction using new blends with alcohol, nanoparticle, and essential oil

Biodiesel is considered one of the alternative replacements to fossil fuels. However, the major challenge associated with its application in diesel engines is the higher level of NOx emissions. Fuel modification technologies, where biodiesel is blended with various additives and fuels, have emerged as a distinguished method in recent years to improve engine performance and reduce NOx. The study aims to reduce NOx emissions by fuel modification techniques. Five blends were prepared using Tucuma biodiesel along with ethanol, carbon nanotubes, and eucalyptus oil. The prepared blends were deployed to a test bed engine at rated speed and by varying loads to investigate performance, emission, and combustion characteristics. The results revealed that ethanol-blended fuels such as DE10 and TB10E10 had reduced the NOx emissions by 51.37% and 9%, respectively, at lower loads compared to diesel. Although the nanoparticle blend exhibited increased NOx emissions compared to diesel, it demonstrated reductions of 4.1%, 4.56%, 7.2%, and 3.1% at loads of 25%, 50%, 75%, and 100%, respectively, compared to TB10. The study highlights various tradeoffs observed between operating conditions and engine parameters for the blends, as detailed in this research. The study found that blends TB10E10 and TB10E10CNT20 exhibit improved performance close to that of diesel and reduced NOx and CO emissions compared to that of diesel and TB10. The study recommends further exploring the impact of injection rates with ethanol-blended fuels as they showed longer ignition delays since advancing the injection can create better combustion with ethanol blends.