Influence of nano additives on Diesel-Biodiesel fuel blends in diesel engine: A spray, performance, and emissions study

Enhancing the suitability of biodiesel for IC engines with inclusion of fuel additives has emerged as a promising avenue of research in recent years. Nanoparticles (NP_s) as fuel additives have witnessed significant advancements as they offer several advantages like higher surface area, improved heat transfer capabilities, and strong catalytic properties. These attributes boost combustion processes and reduce exhaust emissions. Consequently, it is of utmost importance to comprehensively understand the influence of NP_s when incorporated into biodiesel and its blends. Recent reviews have revealed the effect of nano additives on performance, combustion, and emissions, however, the effect of NP_s on fuel spray characteristics has not been clearly understood due to scarce literature available. This review includes the combined effect of fuel spray characteristics, thermal performance, and exhaust emissions, incorporating the fuel preparation methodologies, analysis of fuel stability, and properties for diesel–biodiesel with nano additives from the last 10 years of research. The findings indicate that NP_s yield favorable outcomes in enhancing atomization quality, optimizing engine performance, and mitigating exhaust emissions. For instance, the addition of 50 ppm of CeO₂ to diesel-ethanol reduced penetration length and increased spray cone angle by −2.16 % and +4.3 % in contrast to 25 ppm of CeO₂. BTE improved by 1.58 %, 1.62 %, and 2.34 % with the inclusion of 40, 80, and 120 ppm of Fe₂O₃ NP_s in Mauha biodiesel. CO emissions decreased by 9.78 % for TiO₂ blends, 21.84 % for Al₂O₃ blends, 17.10 % for CuO blends and 6.38 % for CeO₂ with respect to B10. Nonetheless, there remain several unresolved challenges, with the cost of production and long-term fuel stability standing out as a critical factor that must be addressed to establish nano fuels as a financially viable alternative fuel source.