Numerical simulation of methane slip from marine dual-fuel engine based on hydrogen-blended natural gas strategy

Abstract

This study examines the effect of a hydrogen-blended natural gas strategy on methane slip in two-stroke marine engines using numerical simulation. A combined simulation model, integrating a 1-D engine model from GT-POWER and a 3-D CFD model from CONVERGE, was developed and validated with experimental data. Subsequently, the effects of hydrogen molar fraction and energy fraction on methane slip were investigated. It was demonstrated that an appropriate hydrogen doping ratio in natural gas can effectively reduce methane slip. The methane slip decreased with an increase in the hydrogen molar fraction. The maximum reduction in methane slip was 26.76% when the molar fraction of hydrogen was 40% and the equivalent CO2 emission decreased by 142.78 g/kWh. Furthermore, with an enhanced energy fraction of hydrogen, a decrease in methane slip from 10.00 g/kWh to 5.83 g/kWh was observed. The CO2 emission was reduced by 143.86 g/kWh, and the equivalent CO2 emission (CO2 + 36 × CH4) was reduced by 293.80 g/kWh. However, there was a slight increase in indicated specific fuel consumption by 0.03 g/kWh and a decrease in power output by 54.6 kW. The findings offer theoretical guidance and technical suggestions for mitigating methane slip in marine dual fuel engines.