The role of water-in-diesel emulsion and its additives on diesel engine performance and emission levels: A retrospective review

Air pollution caused by the diesel engines has shown much interest in the domain of eco-friendly diesel fuels since enhanced environmental and human health are of concern. In order to obtain the efficient energy development with less polluted environment with existing diesel engines, continuous efforts have gone into research and development of water-in-diesel (W/D) emulsion fuels, which have the potential to reduce nitric oxides (NOx) and particulate matter (PM) emissions simultaneously with improved performance level. The current discussion addresses the principle of W/D emulsion fuel, emulsion fuel stability, physico-chemical properties and effect of W/D emulsion fuel on combustion, performance and emission characteristics. In addition, role of nano-additives in W/D emulsion fuel, nano-fuel synthesis and its influence on engine performance and emission characteristics are also discussed. The survey of earlier reports led to the decision that the optimization of engine parameters, nano-particle size confirmation in nano-fuel and its handling from engine exhaust are the details to be studied in the domain of W/D emulsion fuel engine.