Comparison of combustion and emission characteristics of a diesel engine fueled with diesel and methanol-Fischer-Tropsch diesel-biodiesel-diesel blends at various altitudes.

Abstract In this research, a comparative study of combustion characteristics, performance and emissions of a turbocharged diesel engine fueled with diesel and methanol-Fischer-Tropsch (F-T) diesel-biodiesel-diesel blends at various simulated altitudes (0 m, 3500 m and 5500 m) were conducted. The blends were composed of diesel, methanol, F-T diesel and biodiesel at volume fractions of 65%, 15.2%, 15.6% and 4.2%, respectively. Diesel was used as the baseline fuel, methanol, F-T diesel and biodiesel were used to improve the atomization characteristics, cetane number and stability of the blends, respectively. The results indicated that the cylinder pressure, pressure rise rate and heat release rate of the engine fueled with the blends were lower than those of the diesel at an altitude of 0 m, but higher at an altitude of 5500 m. Peak torque values for the test fuels both appeared at 1400 rpm near the sea level and the speeds corresponding to the peak torque values increased with altitudes. The use of the blends improved the engine power and economic performance at low-speed ranges at an altitude of 3500 m but a dramatically reduce was observed at 5500 m. Compared with the diesel, the particulate matter (2.5 (PM 2.5)) for the blends was markedly lower, while a slightly higher in NOx at various altitudes. [ABSTRACT FROM AUTHOR]