Numerical research of the injected exhaust gas recirculation strategy on a two-stroke low-speed marine diesel engine

Abstract

To meet the stringent emissions legislation and higher fuel economy requirements of the low-speed two-stroke marine diesel engine, a new method named Injected Exhaust Gas Recirculation (IEGR) strategy was proposed in this paper. The effects of the IEGR strategy on the fuel/air mixture quality, combustion performance, and emission characteristics were numerically investigated. The simulation results show that the IEGR strategy could not only increase the in-cylinder swirl ratio but also achieve the distribution of EGR stratification. As a result, compared with the base case, both reduction of brake specific fuel consumption (BSFC) and NOx emissions could be realized by the IEGR strategy. Additionally, based on stratified EGR distribution, the NOx emissions could be further reduced by adjusting the fuel injection angle to control the main combustion area to be restricted to the high EGR rate region. Finally, on the premise of meeting the Tier III emission standards, the BSFC of the engine by using the IEGR strategy is reduced by 2.73% compared with the base case (Tier II emission standards). This study provides a new and reasonable solution for low-speed two-stroke diesel marine engines to meet the Tier III standards with better fuel economy.