Experimental study demonstrates reduced methane slip via optimized pilot injection in dual-fuel engines, indicating trade-offs between greenhouse gases and nitrogen oxides.
Key Points
To evaluate how pilot injection timing, duration, pressure, and multi-stage strategies influence combustion performance and exhaust emission profiles in a methane-diesel dual-fuel engine.
Acquired combustion and exhaust data across varying diesel pilot injection timings, injection durations, and injection pressures exceeding 1000 bar.
Tested multiple multi-stage pilot injection strategies, specifically evaluating a Pre 2nd Pilot configuration against single-stage profiles.
Advancing pilot injection timing up to 16° before top dead center increased indicated mean effective pressure (IMEP), after which IMEP plateaued and end-gas auto-ignition emerged.
Increasing injection duration and elevating injection pressure above 1000 bar reduced unburned methane emissions and raised IMEP, but stimulated end-gas auto-ignition and increased nitrogen oxide emissions.
The Pre 2nd Pilot multi-stage strategy achieved the shortest combustion duration, highest IMEP, lowest coefficient of variation of IMEP, and lowest overall greenhouse gas emissions, with relatively low nitrogen oxide emissions compared to conditions with equivalent greenhouse gas reductions.