Endoscopic visualization of combustion flame to study the effect of 1,4-dioxane as an additive on the spatial flame characteristics of spark ignition engine

Abstract

This paper attempts to explore the impact of the addition of 1,4-dioxane (DOX) with gasoline by volume proportion of 1.5%, 3% & 5% as a performance enhancer in the spark-ignition engine. The DOX possess two oxygen molecules in its chemical structure with good flammable characteristics, and also results in good miscibility and stability with gasoline. The endoscopic technique is employed for spatial visualization and characterization of the combustion flame on the crank angle basis. Spatial flame characteristics and temperature distributions are evaluated by processing the captured digital images. The result shows that flame initiation and propagation are advanced and faster with the addition of DOX in the gasoline respectively. The ring structure and inherent oxygen content of the DOX increased flame speed and improved the combustion characteristics. From the performance and emission analysis, it is found that brake thermal efficiency of gasoline fuel is 24.72%, which is less when compared to the brake thermal efficiency of DOX3 (gasoline 95% + DOX 5%), whose value is 25.42% at full load condition. The HC and CO emissions are decreased by about 6.8% and 10.3% for the DOX3 blend when compared to sole gasoline at full load. This is due to the presence of inherent oxygen and faster burn rate exhibited by the DOX blend which promotes fuel oxidation. NOx emission increased slightly with an increase in the DOX percentage.