Experimental Study of Diesel Fuel Effects on Direct Injection (DI) Diesel Engine Performance and Pollutant Emissions

Abstract

An experimental investigation was conducted to specify the effect of diesel fuel composition and its physical and chemical properties on direct injection (DI) diesel engine performance characteristics and pollutant emissions. Engine tests were made on a single-cylinder naturally aspirated DI diesel engine (Lister LV1), which is located at the laboratory of the authors, at various operating conditions using seven conventional diesel fuels. The test fuels indicate variable hydrocarbon composition and physical and chemical properties, and they were prepared under a European Union research program aiming to identify future fuel formulations for use in modern DI diesel engines. Emphasis was given to the examination of the effect of diesel fuel density, viscosity, and compressibility factor on the fuel injection system, engine combustion characteristics, and diesel-emitted pollutants. Having observed that many diesel fuel parameters are strongly interrelated, we carried out a multivariable statistical analysis to determine the fuel property pairs that are statistically independent. Using experimental findings for pollutant emissions and independent fuel property pairs, a linear multiple regression analysis was conducted to identify potential correlations between diesel-emitted pollutant emissions and the fuel parameters. The sensitivity analysis revealed that soot emissions depend upon fuel viscosity, cetane number, and fuel volatility, whereas NO, CO, and HC emissions mainly depend upon fuel aromatic content. The evaluation of experimental results showed that reductions of soot, NO, and CO emissions can be attained with the reduction of the distillation temperature and the increase of paraffinics/napthenics ratio, which mainly provide the reduction of fuel viscosity and, secondarily, the decrease of the density and increase of the compressibility factor.