Combustion and Hydrocarbon (HC) Emissions from a Spark-Ignition Engine Fueled with Gasoline and Methanol during Cold Start

摘要

The effects of the ambient temperature and the amount of fuel injected per cycle on the cold-start firing behavior as well as the combustion and the hydrocarbon (HC) emissions of an electronically controlled inlet port injection spark-ignition (SI) engine fueled with gasoline and methanol, respectively, during the cold start were studied experimentally by means of a single-cycle fuel injection strategy. The results showed that the amount of fuel injected per cycle significantly affects the gasoline-fueled engine cold-start reliability. A proper amount of fuel injected per cycle ensures a reliable start of the gasoline-fueled engine. The ambient temperature affects most significantly the cold-start ability of the methanol-fueled engine, and the amount of methanol injected per cycle takes second place. With the ambient temperature below 16 ℃, the methanol-fueled engine cannot be started reliably without auxiliary start aid even with a large amount of methanol injection under low injection pressure. Using a glow plug to heat the engine inlet manifold results in a reliable firing of the methanol-fueled engine and may realize an ideal firing in the next cycle combustion after fuel injection. The ambient temperature is closely related to the fuel vaporization and fuel-air mixture preparation, especially at cold start. With a rise in the ambient temperature, the methanol and gasoline injection amounts per cycle sufficient for the reliable firing during cold start of the engine reduce obviously and the HC emissions decrease significantly. At the same injection timing, the gasoline-fueled engine may realize an ideal firing in the next cycle combustion after fuel injection and the firing of the methanoi-fueled engine occurs one cycle later than that of the gasoline-fueled engine.