Computational study of nozzle spray-line distribution effects on stratified mixture formation, combustion and emissions of a high compression ratio DISI methanol engine under lean-burn condition

Abstract

In this paper, five different spray-line distribution nozzles were designed to evaluate the effect of the nozzle spray-line distribution on stratified-charge combustion of methanol engine. Nozzle spray-line distribution characteristics, the stratified mixture formation, combustion and emissions of a high compression ratio direct-injection spark-ignition methanol engine for different spray-line distribution nozzles under lean-burn condition were numerically simulated. Simulation results showed that a non-uniform spray-line distribution nozzle of a 10-hole × 0.30 mm was conducive to form an ideal stratified mixture and obtain better combustion and engine performance. The maximum in-cylinder pressure of nozzle A was approximately 50.5% higher than that of nozzle E. The ignition delay and combustion duration of nozzle A were approximately both 20% lower than nozzle E. Nozzle A had lower unburned methanol, CO and soot emissions. The nozzle order of the highest NO emission was: A ≫ B > C > D > E. NO emission of nozzle A was approximately 13.6 times higher than that of nozzle E. According to the combustion and emission performance tradeoff, the nozzle order was: A > B > D > C > E. Nozzle A was preferred for actual spark ignition methanol engine applications.