Spray Ignition of Primary Reference Fuels Blended with Ethanol and 2,5-Dimethylfuran

The Advanced Fuel Ignition Delay Analyzer (AFIDA) apparatus can measure the ignition delay times with high repeatability within very short time. The device also requires small quantities of fuel samples. During AFIDA experiments, liquid fuel is injected into a hot and constant-volume chamber at high pressure. This way the ignition of the spray combines the effects of realistic influences like liquid evaporation and combustion chemistry. The present work investigates the effects of blending ethanol and 2,5-dimethylfuran with primary reference fuels (i.e., mixtures of iso-octane and n-heptane). The primary motivation of this study is to show the differences in ignition delay times of different gasoline-ethanol and gasoline-2,5-dimethylfuran blends where both physical mixing and chemical kinetics have considerable influences. The primary reference fuel is considered as the gasoline surrogate in this work. The study has been conducted at a range of temperatures and pressures. Both first stage and second stage ignition have been observed for spray ignition. The effect of pressure on the ignition delay time of pure ethanol and 2,5-dimethylfuran has been found to be minimal. Even for the primary reference fuel, the effect of pressure gradually diminishes with decrease in initial temperature. The effect of temperature on the second stage ignition delay time of ethanol and 2,5-dimethylfuran is stronger than the same for the primary reference fuel. These results are helpful for the development of better gasoline combustion technologies.