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The rapid depletion of petroleum reserves due to rising fuel consumption highlights the need for alternative energy sources. Research shows that biodiesel is a viable substitute for modern (combustion engine) CI engines, with properties like pure diesel. Current efforts focus on improving the efficiency, eco-friendliness, and cost-effectiveness of biodiesel while reducing emissions. This study reviews the impact of injection parameter variations on the performance, combustion, and emissions of CI engines running on biodiesel-diesel blends and pure diesel. Efforts are being made to prove the applicability of biodiesel in the modern-day CI engines in an efficient, ecofriendly, and economical manner by improving the performance and mitigating the exhaust emissions. The fuel injection system is key to engine performance and emissions. This study reviews how variations in injection parameters affect the performance, combustion, and emissions of CI engines using biodiesel-diesel blends and pure diesel. It aims to optimize injection strategies for biodiesels from edible and non-edible oils, as well as pure diesel, to meet Bharat Stage-VI norms while maintaining engine efficiency. This study provides better injection Sparameter combinations by varying fuel injection strategies for different biodiesels derived from both edible and non-edible oil seeds, as well as pure diesel and their blends, using the same diesel CRDI engine. The goal is to maintain the performance and exhaust emissions of the CI engine to meet the upcoming Bharat Stage-VI norms.

In the present study, a binary biofuel blend was prepared by blending soy methyl ester (SME100) and methyl oleate (MO) SME50-M50 with diesel. The physiochemical properties of blended fuels were also investigated. The performance and emissions characteristics of all fuel blends were estimated using a common-rail direct injection (CRDI) engine. The outcomes demonstrate a reduction in brake-specific fuel consumption (BSFC) when enriched biodiesel is used in comparison to SME100, nonetheless by the virtue of viscosity and heating value there is an increase in the BSFC value when compared to diesel. The average BSFC values were obtained as 5.3% (E25), 10.6% (E50), 17.5% (E75), 30% (SME100) and 14.9% (SME50-M50) higher than that of diesel. BTE was found to be highest for E25 and lowest for SME100 among all the blends. NOx emissions with blended biodiesel were slightly higher than diesel on account of MO being unsaturated, resulting in shorter ignition delay. The average NOx values obtained were higher than that of diesel and the corresponding values are 2.91% (E25), 4.1% (E50), 5.8% (E75), 8.3% (SME100) and 15.8% (SME50-M50). As a result of the increased oxygen content of the fuel, the concentrations of UHC and CO depreciated with the rise in concentration of soy methyl ester and MO (SME50-M50). Currently, Euro 6.2, which is the most recent emission regulation, uses 10% biofuel (B10); however, the results of this study establishes that E25, as an alternate fuel, complies with the contemporary engines without requiring any engine modifications.

The fast depletion of the petroleum reserves and the rising environmental threats have created an urgent need for sustainable-alternate fuels for the transport and agricultural sectors. In this regard, the ternary blends (diesel–biodiesel-alcohol) have the potential to address the above concerns as they offer huge potential in mitigating exhaust emissions and enhancing engine performance. In the present work, jatropha biodiesel and heptanol have been used as oxygenated additives in the ternary blends in order to save considerable quanta of diesel fuel by restricting its volumetric content to only 40 %. In addition, the fuel injection pressure (IP) is a vital factor that determines the performance and emissions of CI (Compression Ignition) engines. The impact of variations of IP on the performance and emission of CI engine fuelled with ternary blends needs fresh investigation. The previous works lack the analysis of high IP variation in diesel engine fuelled with ternary blend that involve higher alcohol. This experimental work aims to investigate the improvement in CI engine performance and reduction in the exhaust emissions by applying varied IP to the engine powered with diesel-jatropha biodiesel-heptanol blends. In this context, four different ternary blends were prepared by varying biodiesel and heptanol contents from 20 to 50 % and 10–40 %, respectively. The ternary blends were tested in a single-cylinder, four-stroke, direct-injection CI engine by varying the IP from 400 to 500 bar at 10 and 20 Nm engine loads while maintaining the engine speed at 1800 rpm. The results indicated that DBOHep20 achieved a maximum reduction of CO and smoke emissions by 57.4 % and 91.6 %, respectively. The lowest NOx emission was achieved by DBHep40 which was found to be 13.27 % lower than diesel. In the case of engine performance, DBHep40 resulted in lowest BSFC and highest BTE which were found to be just 12.5 % higher and 3.9 % lower than diesel, respectively. The lower IP leads to lesser emissions with a slight compromise with engine performance.

The growing energy demand and non-renewable nature of conventional diesel had shifted the focus of researchers on the search for alternate fuels. Intensive research works, experiments and tests have been conducted in alternate fuels by keeping in view their non-polluting, environment-friendly, sustainable and renewable nature at the core. Consequently, biodiesel and alcohols have emerged as promising oxygenated fuel additives blended with conventional diesel and can be employed in modern-day diesel engines with the least modifications in them. The current work presents a review analysis of the performance and emissions characteristics of blended fuels comprising biodiesel, alcohols, and pure diesel in different blend ratios. The similarity in the physical-chemical properties of biodiesel and alcohol with pure diesel makes them suitable for diesel engines. The higher oxygen content of biodiesels and alcohol ensures complete combustion, thus reducing diesel engines’ detrimental exhaust emissions. However, the lower calorific value of biodiesels and alcohols negatively affects engine performance. In general, biodiesel-diesel blends in varied volumetric proportions were used in diesel engine, however, many researches have shown that B20 blend (biodiesel – 20%, diesel – 20%) offers optimized performance and emissions. The ternary blends comprised of biodiesel-alcohol-diesel offer tremendous potential as future fuel. The inclusion of alcohols as fuel additives in the form of ternary blends needs fresh review and compilation of the updated works. Therefore this review analysis is based on the contribution of ternary blends in increasing the performance and mitigating the emissions of the diesel engine. The appropriate blend composition of biodiesel and alcohol in pure diesel has been scrutinized. The inclusion of biodiesel in the range of 10% to 80% and alcohol around 5% to 45% in diesel proved suitable. Thus, ternary blended fuels prove to be promising alternate fuel in meeting the fuel demand and simultaneously addressing the present and future environmental concerns.