Comparative analysis of combustion and emission characteristics of synthetic e-Fuel and gasoline in a Spark-Ignition engine

Abstract

This study aims to evaluate the practical applicability of e-fuel as a carbon-neutral fuel for conventional internal combustion engine (ICE) vehicles by conducting a comparative analysis with commercial gasoline under identical conditions. A 1.5-liter turbocharged gasoline direct injection (GDI) engine was used to comprehensively assess combustion characteristics, output stability, brake specific fuel consumption (BSFC), gaseous emissions (CO, THC, NOx), knock intensity, and particulate number (PN) emissions under part-load conditions and catalyst heating condition after cold start. In addition, combustion visualization and fuel property analysis were conducted to investigate the underlying causes of each phenomenon. The results showed that e-fuel maintained combustion stability and engine performance comparable to gasoline under most conditions, while achieving load-dependent emission reductions: THC decreased by 27-32 %, corresponding to roughly one-third lower levels than gasoline across the tested loads, and CO decreased by 1-15 %, with NOx remaining comparable to gasoline. Knock intensity remained below the critical threshold for both fuels even under minimum spark advance for best torque (MBT) conditions, confirming that e-fuel can operate stably within the existing ignition control strategy. However, under high-load and cold-start conditions, PN emissions were significantly higher with e-fuel, which is attributed to increased nucleation-mode particle formation caused by oxygenated compounds and high-boiling-point aromatic components in the fuel. In conclusion, e-fuel demonstrates strong potential as a practical low-carbon alternative fuel compatible with existing ICE platforms. With further optimization of fuel composition and the application of appropriate after-treatment systems, it is considered highly feasible for real-world deployment in transportation sectors.