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- Experimental Investigation Of Disruptive Burning Phenomena On Nanofuel DropletsPublication . Ferrão, Inês; Mendes, Miguel; Moita, A. S.; Silva, A. R. R.The transport sector plays a crucial aspect in society and economic evolution. However, improper energy management has negatively impacted health and the environment. Thus, the use of sustainable and green fuels in the aeronautical industry has been implemented due to environmental concerns and the depletion of fossil fuels. The introduction of biofuels, a renewable energy source in the transportation sector, has shown advantages in terms of pollutant reduction. Recently, the addition of nanoparticles in the combustion of biofuel has been studied with the purpose of enhancing its combustion characteristics. Consequently, the present work evaluates nanofuel single droplet in a falling droplet method. In this way, the fiber suspension effect was neglected, and droplets in a size of 250 μm were evaluated. To this end, a comparison between pure biofuel and a nanofuel at two furnace temperatures (T = 800 ºC and T = 1000 ºC) was performed. The results reveal that disruptive burning phenomena occur when aluminum nanoparticles are added to the biofuel. Consequently, a micro-explosion determines the end of the droplet lifetime, mainly affected by the furnace temperature.
- Combustion characteristics of a single droplet of hydroprocessed vegetable oil blended with aluminum nanoparticles in a drop tube furnacePublication . Ferrão, Inês; Silva, André; Moita, A. S.; Mendes, Miguel; Costa, MárioThis study examines the burning characteristics and disruptive burning phenomena of single droplets of aluminum nanoparticles (n-Al) stably suspended in a biofuel (HVO). The biofuel used in the present work is a promising alternative fuel already tested in the aviation sector to reduce greenhouse gas and pollutant emissions. Experiments were conducted with two particle sizes (40nm and 70nm) and two particle concentrations (0.5 wt.% and 1.0 wt.%) to study its influence when added to the biofuel. The effect of size and concentration of the aluminum nanoparticles was studied at 1100 °C in a drop tube furnace. This experimental facility allows the study of combustion characteristics of falling droplets, ensuring there is no influence of the supporting fiber on the burning rate and disruptive burning phenomena occurrence. A CMOS high - speed camera coupled with a high magnification lens was used to evaluate the droplet size, burning rate, and micro-explosions. Based on this procedure, pure biofuel droplets were compared with those of biofuel blended with nanoparticles. The results suggest that the combustion characteristics of pure HVO can be enhanced with the addition of aluminum nanoparticles. Furthermore, by decreasing the particle size, a slight increase in the burning rate of nanofuels was noticed. Additionally, an increase in the particle concentration leads to a pronounced increase in the burning rate. The particle concentration also influences the delay and intensity of micro-explosions, disruptive burning phenomena detected at the end of the droplet lifetime.
- Single droplet combustion of aluminum nanoparticles added to a biofuel: effect of particle concentration and ambient temperaturePublication . Ferrão, Inês; Mendes, Miguel; Moita, A. S.; Silva, AndréThe fast expansion and growth of the aviation sector, coupled with the greenhouse gas andpollutant emissions, requires urgent solutions. A starting point to change this sector paradigmcould be a new energy source for aviation gas turbines, focused on potential carbon neutral fu-els, e.g., biofuels. A possible solution is nanoparticles addition to improve the biofuel propertiesand mitigate the problems inherent to their use. The present work experimentally evaluates thecombustion characteristics of single droplets of HVO (NExBTL) with aluminum nanoparticles.The ambient temperature was varied from600°Cto1000°C. Three particle concentrations (0.2,0.5, and 1.0 wt.%) were investigated with a fixed particle size of 40nm. This study examinedthe combustion of droplets with an initial diameter of 250μmusing a falling droplet method.The results reveal that for nanofuels, the droplet size evolution curve is not in agreement withD2– law and display a unique disruptive burning phenomenon at the end of the droplet life-time. It was noticed that the burning rate of biofuel is considerably enhanced with the addition ofnanoparticles, being the highest value for the nanofuel with a particle concentration of 1.0 wt.%.