Abstract
The puffing and micro-explosion of a single burning droplet comprised of neat diesel, rapeseed methyl ester (RME); binary fuel mixtures of diesel–ethanol, diesel–RME, RME–ethanol; and ternary microemulsion of these fuel blends at various compositions have been studied using high speed backlight imaging method. Fuel droplet was suspended on the tip of a 130μm gauge thermocouple and it was ignited using a glow plug heater. Based on the temporal variation of droplet projected area, the characteristics of fuel droplets studied were classified into smooth burning, puffing and explosion. A ternary plot has been proposed to identify the mixture composition of the blends that can result in smooth burning, puffing and explosion. Micro-explosion phenomenon was observed in the ternary blends with ethanol percentages between 10% and 40%. Secondary droplets resulted from the puffing and explosion of suspended parent droplet were observed to undergo further explosion. The time scales associated with complete disintegration of secondary droplets are found to be comparable to the mixing and the chemical reaction time scales of sprays in diesel engines.
Highlights
In recent times, search for alternative fuels has been intensified due to depleting fossil fuel reserves and environmental impacts.With the increasing concern of the environment and more stringent regulations on exhaust emissions, the reduction in engine emissions is a major research objective for engine development.Ethanol is an attractive alternative fuel because it can be a renewable bio-based resource and it has hydroxyl group, thereby providing the potential to reduce particulate emissions in compression ignition (CI) engines
This study focuses on exploring puffing and micro-explosion phenomenon using suspended droplets of diesel–biodiesel
Adding rapeseed methyl ester (RME) to the diesel–ethanol mixtures resulted in a stable and clear microemulsion, otherwise unstable, milky emulsions. This shows that fatty acids in RME act as surfactant, which aids in the formation of a stable microemulsion
Summary
Search for alternative fuels has been intensified due to depleting fossil fuel reserves and environmental impacts.With the increasing concern of the environment and more stringent regulations on exhaust emissions, the reduction in engine emissions is a major research objective for engine development.Ethanol is an attractive alternative fuel because it can be a renewable bio-based resource and it has hydroxyl group, thereby providing the potential to reduce particulate emissions in compression ignition (CI) engines. Search for alternative fuels has been intensified due to depleting fossil fuel reserves and environmental impacts. With the increasing concern of the environment and more stringent regulations on exhaust emissions, the reduction in engine emissions is a major research objective for engine development. Ethanol is an attractive alternative fuel because it can be a renewable bio-based resource and it has hydroxyl group, thereby providing the potential to reduce particulate emissions in compression ignition (CI) engines. Complete replacement of diesel with ethanol for CI engines is not a feasible solution due to differences in physical and chemical properties, which affects injection and combustion processes. Blending ethanol with diesel eliminates the modifications to the engine fuelling and combustion systems
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