Split Injection Strategy for Waste Cooking Oil Biodiesel- Hydrogen Fueled Reactivity Controlled Combustion (RCCI) Process

Compression ignition engines using an electronically controlled Engine Management System (ECM) are gaining attention for a high-speed Electronic Control Unit (ECU) controlled governor with a closed-loop fuel management system. This enables the sharp cutting of fuel required for torque-based or demand speed applications. The stringent emissions regulations and inflation in fuel prices present a major challenge for the engine research community. This work investigates the potential of a split injection strategy along with reactivity-controlled compression ignition combustion process to achieve ultra–low Hydro- Carbon (HC), Carbon Monoxide (CO), Nitrogen Oxides (NOx) -smoke trade at full load operation. For this purpose, the main fuel used is Hydrogen (H2), and the pilot fuel used is Waste Cooking Oil Biodiesel (WCOBD) 20% blend with diesel 80% (v/v) as WCOBD20%. Split injection strategies parameters used are energy share, Pilot Injection Angle (PIA), and Main Injection Angle (MIA). The engine operated knock-free with hydrogen (5–15 LPM) as the Rate of Pressure Rise (RPR) remained below 6 bar/°CA and no hunting was observed. Major Findings: The results demonstrate effective combustion regulation with improved combustion efficiency using hydrogen at a 4ms injection duration (10 LPM volume flow rate), corresponding to approximately a 32% energy share. While balancing the trade-off between NOx-smoke and HC-CO emissions, Further retarded injection timing increased performance by 25% with HC-CO emission reduction up to 20% with a penalty of NOx emissions by 5% and smoke emissions by 6% raise.