Low-Temperature Combustion Kinetics of Methanol-Blended Gasoline and Methanol Synthesized Dimethyl Ether

Low-temperature combustion (LTC) is a desirable mode of fuel utilization that ensures low particulate matter (PM) and oxides of nitrogen (NOx) emissions. Low-temperature combustion kinetics of five different methanol-blended gasoline containing 10, 20, 30, 40, and 50% of methanol by volume, respectively, were compared with neat gasoline. Methanol addition in gasoline enhanced low-temperature combustion behavior compared to neat gasoline due to the improved evaporation and mixing characteristics. Unlike the combustion efficiency and power, which showed marginal improvement; carbon monoxide (CO), and NOx emissions dropped significantly with the increase in methanol/gasoline ratio. The effect of methanol/gasoline ratio on different low-temperature chemical pathways was investigated to find an optimum value in terms of combustion performance and emission. Operating strategies to reduce and mitigate unburned methanol emission are discussed, which arose at higher methanol concentrations. Dimethyl ether (DME) is an attractive fuel for compression ignition engines. Since it exhibits low-temperature chemistry, it is particularly suited for homogeneous charge compression ignition (HCCI) Engines. Active radicals generated by low-temperature transient plasma (TP) discharge offer a viable approach to control the combustion phasing of an HCCI engine. In this study, the low-temperature kinetics of DME was explored employing a non-equilibrium plasma ignition strategy using zero-dimensional modeling. A sensitivity analysis of the first and second-stage ignition delays was carried out. The negative temperature coefficient (NTC) regime revealed interesting distinctions between DME and other low molecular weight alkanes. The presence of a thermal bottleneck was found to decrease the efficiency of plasma assistance.