The purpose of the investigation presented here was to compare the effects of fuel composition on combustion parameters, emissions and fuel consumption in engine tests and simulations with five fuels: a Diesel-water emulsion, a Diesel-ethanol blend, a Diesel-ethanol blend with EHN (cetane number improver), a Fischer-Tropsch Diesel and an ultra-low sulfur content Diesel.
The engine used in the experiments was a light duty, single cylinder, direct injection, common rail Diesel engine equipped with a cylinder head and piston from a Volvo NED5 engine. In tests with each fuel the engine was operated at two load points (3 bar IMEP and 10 bar IMEP), and a pilot-main fuel injection strategy was applied under both load conditions. Data were also obtained from 3-D CFD simulations, using the KIVA code, to compare to the experimental results and to further analyze the effects of water and ethanol on combustion.
The experimental data indicated that the lower aromatic content of Fischer-Tropsch Diesel fuel resulted in reduced soot emissions compared to conventional Diesel. Use of Fischer-Tropsch Diesel also gave lower NOx emissions. The Diesel-ethanol blend gave a large reduction in soot emissions, but higher NOx emissions than the Diesel-water emulsion. The lower heating value of the Diesel-water emulsion resulted in increased fuel consumption in comparison to the Diesel-ethanol blend and Diesel. The addition of the cetane number improver (EHN) to the Diesel-ethanol blend further reduced NOx emissions.