Despite significant advancements in internal combustion engine efficiency, fossil fuels still hinder progress toward sustainable energy. Syngas, a gasification byproduct of hydrogen and carbon monoxide, is a promising transitional fuel due to its compatibility with existing combustion technologies, improved efficiency, and lower emissions. It is well-suited for HCCI engines, known for high thermal efficiency and reduced NOₓ and particulate emissions. However, Syngas combustion requires elevated intake temperatures or admission pressures to ensure optimal thermodynamic conditions. To overcome this, a small quantity of diesel enhances ignition stability and extends the engine’s operational range in dual-fuel combustion.
While most previous experimental studies have focused on syngas-diesel dual-fuel operation in single-cylinder setups, this research expands the analysis to a multi-cylinder engine. It accounts for cylinder-to-cylinder variations, chemical interactions, and thermal distribution, providing insights into combustion stability under realistic operating conditions. A 1.6 L four-cylinder HCCI engine was tested on an experimental bench configured for dual-fuel operation. This study investigates the effect of injection timing of diesel on syngas ignition and combustion, aiming to optimize engine performance and address syngas-related challenges. Combustion analysis was conducted by evaluating key metrics such as torque, IMEP, and combustion phasing markers such as CA10 and CA50, the crank angle at which 10% and 50% of fuel energy is released, respectively. Additionally, the study compares performance of dual-fuel operation and a pure diesel operation with equivalent calorific energy, to assess variations in performance.
The findings underscore the significant influence of diesel pilot injection timing on syngas combustion dynamics in HCCI engines. Adjusting injection timing alters combustion phasing and heat release patterns, directly impacting engine performance. These findings provide valuable insights for optimizing dual-fuel injection strategies, enhancing syngas utilization, and improving the feasibility of multi-cylinder HCCI engines for sustainable energy applications.