Combustion Characteristics of Single Isolated Fuel Droplets of Different Diesel-Biodiesel Blends Derived From Waste Vegetables Oil and Animal Fat

Increasing energy demands due to rapid industrialization and urbanization, stringent emission limits, and depleting sources of conventional fossil fuels urges the scientific community in search of renewable, reliable, cost-effective, and environmentally friendly alternative and sustainable options. Biodiesel has become a center of research initiatives to address these issues as a replacement or a supplement to conventional petroleum-based fossil fuels. Biodiesel derived from waste vegetables oil and animal fat is an interesting solution to face the concerns regarding fossil fuels as well as an effective and environmentally friendly way for the disposal of waste vegetable oil in addition to reusing it for energy production. In the transportation sector, typically biodiesel is used in blends with petroleum-based diesel, and the most common blends are B5 (up to 5% biodiesel) and B20 (up to 20% biodiesel). In this regard, current manuscripts report an experimental study on the combustion characteristics of single isolated fuel droplets of different diesel-biodiesel blends. Five different diesel-biodiesel blends named B5, B10, B15, B20, and B25 were used for the droplet combustion study. Neat diesel (B0) and biodiesel (B100) followed the d2-law of combustion while the blended fuel droplets deviate from the d2-law due to puffing and micro-explosion. Increased combustion rates were observed in blended fuel droplets and the highest increase of around 7% was observed for B15 droplets compared to B0 droplets. There were no significant differences in ignition delay between B0 and blended fuel droplets while B100 fuel droplets showed an increase in ignition delay up to 38% compared to B0 droplets. B10 and B15 fuel droplets showed significant decrease in droplet burning time. Highest decrease in droplet burning time was observed for B15 which was around 8% compared to B0 droplets.