Effects of Cetane Number and Chemical Components on Diesel Emissions and Vehicle Performance

Our research objective is to clarify the effect of the utilization of diesel fuels made from unconventional petroleum sources (GTL, Tar Sand, etc.) on the latest vehicle‛s emission and performance. The target properties studied are mainly cetane number and cyclic compounds. Two diesel vehicles and one engine were used in this study. Varieties of transient driving modes were selected for better understanding under real world driving in the emission test. Startability and operability are examined in the vehicle performance test. It was revealed that the tail-pipe emission from a J-2003 reg-compliant vehicle and the engine-out emission from a J-2005 reg-compliant engine used in this study were changed by cetane number and cyclic compound. For J-2003 reg-compliant vehicle, the decrease in cetane number led to the increase in emissions of THC, CO and NOx, while the increase in cyclic compounds led to increase in emissions of PM, THC, CO and NOx. Meanwhile the emission level at tailpipe from a J-2005 reg-compliant vehicle and engine was very low regardless of fuel properties when the cetane number is above 45 (minimum value of Japanese Industrial Standard: JIS). It was also revealed that white smoke at cold temperature condition, and accelerating time at normal temperature condition of the J-2003 reg-compliant vehicle were changed by cetane number or cyclic compound. The decrease in cetane number led to the increase in THC concentrations at low temperature (0°C), and operability at normal environmental temperature (20°), while the increase in cyclic compounds led to increase the white smoke emissions at low temperature (0°C). Meanwhile, there were little effects on the vehicle performance of the J-2005 reg-compliant vehicle when cetane number was above 45.