Effects of sulfur, aromatics, T50, T90 and MTBE on mass exhaust emission from vehicles with advanced technology - JCAP gasoline WG STEP II report

摘要

An overview of STEP II activity of JCAP gasoline working group is presented. The main evaluation of STEP II was conducted with advanced gasoline-powered vehicle and fuel technologies for reducing exhaust emissions. Four models of prototype vehicles were prepared for evaluation. Three of them were SIDIs with lean NO{sub}x catalysts and another was MPI with three-way catalyst. All test vehicles were designed with the target of 1/6 emission level of the FY 1978 Japanese regulations. Sulfur effects were evaluated by 30,000 km mileage accumulation tests using 2 ppm, and 22 ppm and 86 ppm sulfur gasolines. Exhaust emissions of SIDI vehicles were largely affected by the sulfur content but the degree of effect differed between vehicles. Fur further reduction of SIDI emissions, investigations about "Package technology" of vehicle and fuel - sulfur durability improvement of lean NO{sub}x catalyst and sulfur reduction of fuel - with consideration about "Well to Wheels" CO2 are necessary. Effects of Aromatics (8, 30, 50%), T50 (72, 101, 124 degree C), T90 (119, 150, 183 degree C) and MTBE (0, 6.2, 13.1%) on exhaust emission were also evaluated. Results showed individual tendencies of fuel property effects with each vehicle. It is assumed that the difference is caused by various advanced combustion and aftertreatment systems as well as the level of accuracy and diversification of their respective control systems. Elemental study on combustion analysis is necessary for further mechanism analysis.