Numerical Simulation of the Plasma-Assisted Combustion of Methane HCCI

Abstract

To enhance the lean combustion of methane homogenous charge compression ignition (HCCI) engine and expand the lean-burn limit, a non-equilibrium plasma kinetic model has been used to study the discharge process of methane-air mixture numerically. The effect of the discharge productions on the methane HCCI combustion are studied numerically by using a CHEMKIN-based multi-zone model. The simulation results show that the discharge produced reactive radicals, such as H, O and CH3. These radicals can enhance the combustion of CH4 fueled HCCI significantly. Introduction of 1% (volume fraction of the fuel) of H reduces the ignition delay time of HCCI combustion (with equivalence fuel / air ratio of Φ = 0.5) by about 13 crank angle degrees (°CA), adding the same amount of O reduces the ignition delay time by about 10°CA. Further research shows that, with the increase in the above radicals, the combustion enhancement becomes stronger.