Numerical evaluation of ignition timing influences on performance of a stratified-charge H₂/methanol dual-injection automobile engine under lean-burn condition

Influences of ignition timing (IT) on combustion, carbon monoxide (CO) and nitric oxide (NO) regulated emissions and formaldehyde (HCHO) and unburned methanol (CH3OH) unregulated emissions in a hydrogen (H-2)/methanol dual-injection automobile engine under lean-burn condition were studied numerically. The results demonstrate that at lean-burn (excess air ratio = 2.0) condition, the peak cylinder pressure (PCP), peak heat release rate (PHRR) and peak cylinder temperature (PCT) all decrease with delayed IT, and their corresponding crank angles are also late; ignition delay (ID) and combustion duration (CD) decrease with delayed IT; CO, HCHO and CH3OH emissions increase with delayed IT, while NO emission decreases with delayed IT. At a fixed IT, PCP, PHRR and PCT for with adding 5 % H-2 (R-H2 = 5 %) are higher than those for without adding H-2 (R-H2 = 0 %), and their corresponding crank angles for R-H2 = 5 % are earlier than those for R-H2 = 0 %; ID and CD for R-H2 = 5 % are lower than those for R-H2 = 0 %. CO, HCHO and unburned CH3OH emissions for R-H2 = 5 % are also much lower than those for R-H2 = 0 %, while NO emission for R-H2 = 5 % is also higher than that for R-H2 = 0 %. The influence order of adding H-2 to reduce emissions of engine is: CO > HCHO > unburned CH3OH.