Experimental investigations of methanol fumigation via port fuel injection in preheated intake air in a single cylinder dual-fuel diesel engine

Abstract

Primary alcohols are emerging as promising alternative fuels for diesel engines. Dual-fuel engine operation with port injection (fumigation) of methanol has emerged as a novel concept for simultaneous reduction of particulate matter (PM) and oxides of nitrogen (NOx). This experimental study investigates the effect of intake air preheating on methanol-fumigated agricultural diesel engines. Methanol premixing ratio was kept constant at 50% (M50) for all test conditions. The experiments were performed at a constant speed of 1500 rpm at two intake temperatures of 40 °C and 80 °C, and engine load was varied from 1.25 to 5 bar brake mean effective pressure (BMEP). It was observed that intake air heating influenced the engine’s combustion, performance, and emission characteristics. Higher intake air temperature (M50, 80 °C) resulted in higher peak in-cylinder pressure and brake thermal efficiency (BTE) than the low-temperature case (M50, 40 °C). Higher intake air temperature compensated for the cooling effect due to evaporation of methanol caused by a shorter combustion duration, leading to more efficient energy conversion. Higher hydrocarbons (HC) and carbon monoxide (CO) emissions were observed in addition to lower nitric oxide (NO) emission for M50 vis-a-vis baseline diesel at all loads. The study concluded that intake air temperature significantly affects methanol-diesel dual-fuel engine characteristics and will be an important parameter requiring optimisation before large-scale methanol implementation in agriculture and transport sectors.