The Ignition Delay Period in Dual Fuel Engines

The ignition delay period in dual fuel engines is examined, while employing the gaseous fuels methane, propane, ethylene and hydrogen. It is shown that the changes due to gaseous fuel admission in the temperature and pressure levels during the delay period, the extent of energy release due to preignition reaction processes, variations in the parameters of external heat transfer to the surroundings and the contribution of residual gases are the most important factors that determine the ignition delay characteristics of dual fuel engines. The consequences of these factors on the observed values of the ignition delay were evaluated while using detailed reaction kinetics for the oxidation of the gaseous fuel and employing an experimentally based formula for the ignition of the liquid pilot. It is then suggested that the ignition delay in dual fuel engine operation, in principle can be correlated in terms of the type of gaseous fuel employed, its concentration and other operating conditions.