Applicability of aromatic selection towards newer formulated fuels for regulated and unregulated emissions reduction in CI engine

The fuel composition highly affects formation of toxic pollutants in a diesel engine. The aromatics are found to be prominent fuel components that affect pollutant formation and at the same time help provide lubricity to moving engine parts. Therefore, their effect needs to be addressed systematically. This article elucidates aromatic types and its content effects on fuel atomization, regulated and unregulated emissions. Acoustic emission signals were also recorded for engine noise diagnosis during the exhaustive testing. Five different aromatics namely, ethylbenzene, alpha-methylstyrene, indene, tetralin and methylnaphthalene were blended in ratio of 15, 20 and 25% by mass with dearomatized hydrocarbon fuel and tested in a compression ignition engine. Results reveal that unregulated emissions, carbon monoxide (CO), unburnt hydrocarbon (HC) and particulate matter (PM) increase with aromatic content. However, nitrogen oxides (NOx) and acoustic emissions were found to be maximum with low aromatic content (15%). The polycyclic aromatics (indene, tetralin and methylnaphthalene) produce higher polyaromatic hydrocarbons (PAHs) and carbonyl emissions compared to monocyclic aromatics (ethylbenzene, alpha-methylstyrene). Additionally, polycyclic aromatics with 20% blending produced higher PAHs and carbonyl compound emissions than diesel with 23.6% aromatics. Ethylbenzene showed significantly better results for both spray and emission characteristics compared to the other tested aromatics.