Oxygenated Fuel Additive Option for PM Emission Reduction from Diesel Engines—A Review

As on today, of the two types of engine used in mobility sector, diesel engines offer superior fuel and thermal efficiencies, better durability, greater torque, and higher power output compared to the gasoline engines. However, the diesel engines are a major source of both regulated and unregulated emissions which is responsible for the deteriorating air quality. The problem can be tackled either by using alternate power plant such as hybrid and electrical vehicles or by using alternate source of energy like biodiesel and oxygenated additives to diesel. The second option seems to be more attractive, as it does not need any major modification to the millions of existing engines. In this direction, there is an urgent need to find sustainable and environmentally friendly fuel types for the diesel engine application. In this chapter, the authors embark on the analysis and review of the application of oxygenated alternative fuels such as biodiesel, acetone–butanol–ethanol (ABE) solution and water emulsion as oxygenated fuel reformulation strategies. These strategies are aimed at achieving reduction of engine particulate emissions without much compromise on energy efficiency of the diesel engine. After the careful review of around 115 published literature, it is found that, still more research under controlled conditions is a must on these oxygenated fuels to gain more insight on their effects. This is especially true for the emissions of particulate matter (PM). Further, it is brought out through this review, a combination of factors such as higher oxygen content, more complete combustion and cooling effect to reduce this pollutant. If employed appropriately by having a diesel blend which contains proper amount of biodiesel, ABE solution and a small amount of water (0.5%), the regulated PM emissions can be reduced considerably. What it means is that such oxygenated fuels exhibit excellent performance in both brake thermal efficiency (BTE) and NOx–PM trade-off. This chapter proposes an oxygenated diesel fuel blend not only for scientific study but also for the future practical application.