Development of a direct-injection stratified-charge methanol engine

Abstract

On the basis of the wall-guided, spray-guided, and air-guided technologies related to gasoline direct-injection spark-ignition (DISI) engines, a complex-guided stratified-charge combustion system for a methanol DISI engine was developed. The test engine was a retrofitted four-cylinder diesel engine. The key parameters were optimized numerically and experimentally, such as the location of the swirl deflector, the spatial location of spray, the swirl ratio, the injection and ignition timings, and the needle valve opening pressure. The results show that the direct-injection stratified-charge (DISC) methanol engine can work with an excessive air ratio λ as high as 2.23, and its brake thermal efficiency reaches 29.7 per cent at a speed of 1500r/min, and a brake mean effective pressure of 0.45MPa. The DISC methanol engine exhibits relatively good performance with little cyclic variations, although it is sensitive to induction swirl. The test results indicate that the matching principle is successful. The developed DISC methanol engine can run under variable induction swirl to meet the requirement of stratification combustion under different engine speed operating conditions.