Parametric study of a marine two-stroke dual-fuel engine of low-pressure gas injection with exhaust gas recirculation using CFD

This study aims to investigate the use of exhaust gas recirculation (EGR) to reduce methane slip and increase the thermal efficiency of a marine two-stroke DF engine of low-pressure gas injection, whilst quantifying the EGR impact on the engine performance and emissions parameters. A computational fluid dynamics (CFD) model is developed, validated, and subsequently employed to parametrically investigate the impact of the EGR rate. A new method is proposed to facilitate the convergence of the emissions parameters with EGR. The derived results reveal that the EGR reduces the methane combustion rate, whereas a relatively high EGR rate can considerably improve the engine performance whilst reducing emissions. This study recommends an EGR rate around 50% for the engine operating at 75% load, as compared to the operation without EGR, it results in a 6.3% increase in the indicated mean effective pressure, a 5.8% decrease in the indicated specific gas consumption, and reductions in CH4, equivalent CO2, and NOX emissions by 59.6%, 23.9%, and 91.7%, respectively. This is the first study that proposes and investigates the use of EGR to reduce the methane slip in marine two-stroke DF engines, employing a specific convergence analysis method, providing insights for improving DF engine performance and emissions, hence contributing to the shipping industry's environmental footprint reduction.HighlightsEGR use in marine two-stroke LPDI-DF engines to reduce methane slip and improve performanceSingle cylinder CFD modelling to analyse combustion and emissions characteristicsConvergence method based on consecutive cycle analysis was used to accurately calculate cylinder emissions with EGRRecommended 50% EGR rate results in a 6.3% IMEP increase and a 59.6% methane slip reduction