An investigation on the characteristics of and influence factors for NO2 formation in diesel/methanol dual fuel engine

•The existence of methanol premixed region is the main cause of increased NO2 emission in DMDF mode.•The impact of temperature on the NO2 emission mainly lies on that of temperature on the NO and HO2 radicals.•As the increase of MSP, NO2 emission increases firstly and then decreases.•EGR can reduce the NO2 emission, while slightly increased exhaust backpressure can lead to the increase of NO2.