CFD-Based Analysis of Performance and Emissions in an i-DSI Engine Using Various E-Fuels and Syngas

Abstract

In internal combustion engines (ICE), ongoing research focuses on improving efficiency and reducing environmental emissions. As part of this effort, synthetic fuels like E-Fuels and Syngas have gained attention as promising alternatives to conventional fossil fuels. This study investigates the performance and emission characteristics of four different E-Fuels (E-Hydrogen, E-Methanol, E-Kerosene, and E-Ammonia) and three different Syngas compositions in comparison to conventional gasoline in an i-DSI engine. A validated 3D Computational Fluid Dynamics (CFD) model, based on reference experimental data obtained with gasoline, was used to simulate in-cylinder combustion characteristics. The analysis evaluated in-cylinder pressure, torque, indicated power (IP), indicated mean effective pressure (IMEP), indicated specific fuel consumption (ISFC), and thermal efficiency for each fuel. Significant variations in combustion and performance metrics were observed across the eight fuels. E-Hydrogen exhibited the highest in-cylinder pressure and torque increase (17.95%), along with the highest thermal efficiency improvement (up to 55.20%). In contrast, E-Ammonia showed the lowest performance, with a 16.68% reduction in torque. Among the Syngas compositions, Syngas-C (with the highest H₂ content) achieved the best performance. CO₂, CO, and HC emissions were zero for carbon-free fuels (E-Hydrogen and E-Ammonia), while NO_x emissions were highest with E-Hydrogen and lowest with gasoline. Additionally, performance metrics were normalized by each fuel’s lower heating value (LHV), revealing that Syngas blends—especially Syngas-C—offered strong energy-based efficiency. This study uniquely presents a comparative and systematic evaluation of E-Fuels and Syngas as next-generation fuel alternatives for ICEs, using CFD-based combustion modeling validated by experimental reference data.