Effect of Oxygenated Fuel on Performance and Emissions of SI and CI Engines: A Review

Abstract

The increasing concern for cleaner combustion and reduced emissions has intensified the exploration of oxygenated fuels in internal combustion (IC) engines. This review analyzes the effects of various oxygenated fuels such as ethanol, methanol, butanol, hydrogen, and dimethyl ether on the performance and emissions of spark ignition (SI) and compression ignition (CI) engines, particularly under different compression ratio (CR) configurations. Key findings from comparative studies reveal that blends like E30 at CR 11:1 can enhance engine power output by up to 14% while adding 1-butanol shortens combustion duration and reduces particulate emissions. In CI engines, using PODE blends (P10–P30) reduced smoke emissions by 27.6%, 41.5%, and 47.6%, respectively, compared to diesel. Ethanol and methanol blend improved brake thermal efficiency (BTE) by up to 13.8% and reduced CO emissions by 33.31%. Notably, CO₂, NOx, and CO emissions decreased by 30%, 22%, and 37%, respectively, when methanol was used in SI engines at a CR of 10:1. However, increases in HC emissions were reported with higher CR. The synergistic use of ethanol at 50% blend (E50) with a CR of 10:1 achieved up to 45% reduction in CO emissions compared to gasoline at CR 6:1. The review concludes that oxygenated fuels, especially when optimized with CR variation, offer significant improvements in engine efficiency and emissions control, and hold strong potential as sustainable alternatives for future fuel applications.