Numerical analysis on knock for a high compression ratio spark-ignition methanol engine

Abstract

Methanol is an alternative, renewable, environmentally and economically attractive fuel. It is considered to be one of the most favorable fuels for internal combustion engines. In this paper, knock in a high compression ratio spark-ignition methanol engine was modeled and investigated using FIRE Code CFD (Computational Fluid Dynamics) calculations. Knocking combustion was simulated under different operating conditions. Finally, the effects of spark timing and EGR (Exhaust Gas Recirculation) techniques for suppressing knock in a high compression ratio spark-ignition methanol engine were studied based on the numerical analysis through the analysis of the thermal efficiency. The results showed that with the increase of the EGR, the thermal efficiency was greatly reduced and the knock occurrence timing was postponed. The use of a high EGR rate and early spark timing had a better thermal efficiency on the knock suppression as compared to the use of a low EGR rate and late spark timing.