Investigation of the mechanism behind the surge in nitrogen dioxide emissions in engines transitioning from pure diesel operation to methanol/diesel dual-fuel operation

In diesel engines, nitrogen monoxide (NO) is the predominant component of nitrogen oxides (NOx) emissions. However, when transitioning to methanol/diesel dual-fuel operation, even with a small percentage of methanol replacing diesel energy (e.g. 10 %), the concentration of nitrogen dioxide (NO 2 ) increases significantly, becoming comparable to that of NO. This study employs multi-dimensional computational fluid dynamics (CFD) modeling to reproduce this NO 2 /NOx surge ratio phenomenon and investigates the underlying mechanism driving the surge in NO 2 emissions, an area insufficiently explored in existing literature. By comparing CFD simulations with and without the NO+HO 2 ↔NO 2 + OH reaction in the chemical…