Design and Simulation of Two Stroke Engines

Design and Simulation of Two-Stroke Engines
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Fig. 7.39 Stratified charging system proposed by the Institut Francois du Pe'trole.
The unburned hydrocarbon emission levels are shown in Fig. 7.41, and they are also
impressively low. Much of the important legislated driving cycle would be below 20 g/kWh.
When an oxidation catalyst is applied to the exhaust system, considerable further reductions
are recorded, and these data are presented in Fig. 7.43. The conversion rate exceeds 91 % over
the entire range of bmep at 2000 rpm, leaving the unburned hydrocarbon emission levels
below 1.5 g/kWh in the worst situation.
Of the greatest importance are the nitrogen oxide emissions, and they remain conventionally
low in this stratified charging engine. The test results are shown in Fig. 7.42. The highest
level recorded is at 15 g/kWh, but they are less than 2 g/kWh in the legislated driving cycle
zone.
The conclusions drawn by IFP are that an automobile engine designed and developed in
this manner would satisfy the most stringent exhaust emissions legislation for cars. More
important, the overall fuel economy of the vehicle would be enhanced considerably over an
equivalent automobile fitted with the most sophisticated four-stroke cycle spark-ignition en-
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