In-cylinder pressure based combustion analysis of cycle-by-cycle variations in a dual spark plug SI engine using ethanol-gasoline blends as a fuel

Abstract

The combustion in Spark Ignition (SI) engine varies from the engine working cycle-by-cycle the ability to predict accurately the pressure allows for a better understanding of the processes that take place in the cylinder The effects of load, compression ratio, and ethanol content on the cycle-by-cycle cylinder pressure variations of a dual spark plug gasoline engine have been investigated experimentally. Cycle-by-cycle cylinder pressure variations were evaluated using coefficient of variation (COV) of maximum cylinder pressure. The results showed that the maximum cylinder pressure increased and corresponding its cycle-by-cycle variations decreased with the increase of load, compression ratio and ethanol content in the blend. Greater variations were observed at lower loads than full load operation of the engine. Highest maximum cylinder pressure and lowest it’s COV were achieved for 20% ethanol by volume in the blend under full load at compression ratio of 10:1. The maximum cylinder pressure crank angle was moved closer to the top dead center as the ethanol fraction in the blend increased. Finally, it can be concluded that the addition of ethanol 20% by volume to the gasoline maintains COV of maximum cylinder pressure at a low level.