The Addition of Particles to an Alternative Jet Fuel

Abstract

The expansion of the research on nanoscale particles demonstrates several advantages in terms of stability and an increased surface area to volume ratio compared to micron-sized particles. Based on this, the present work explores the addition of aluminum particles in hydrotreated vegetable oil (HVO), an alternative jet fuel. To evaluate the influence of particle sizes, nano and micron particles (40 nm and 5 μm) in a particle concentration of 0.5 wt.% were stably suspended in HVO. This study evaluates droplet combustion with an initial diameter of 250 μm in a drop tube furnace under different furnace temperatures (600, 800, 1000 °C). A high magnification lens coupled with a high-speed camera provides qualitative and quantitative data regarding droplet size evolution and micro-explosions. Pure HVO and Jet A-1 were also tested for comparison purposes. The results reveal that the addition of aluminum particles enhances the alternative jet fuel combustion. Furthermore, decreasing the particle size and increasing the furnace temperature enhances the burning rate compared to the pure HVO. Pure HVO presents a burning rate nearly to 1.75 mm2/s until t/D02 = 0.35 s/mm2 at T = 1000 °C. When nanoparticles are added to HVO in a particle concentration of 0.5 wt.%, an improvement of 24% in burning rate is noticed. Conventional jet fuel and pure HVO do not present any disruptive burning phenomena. However, when aluminum particles were added to HVO, micro-explosions were detected at the end of droplet lifetime, regardless of the particle size.

Experimental Investigation Of Disruptive Burning Phenomena On Nanofuel Droplets

“…In this context, the burning rate was examined to understand the influence of aluminum nanoparticles in a biofuel. Figure 6 shows the burning rate for pure HVO and HVO + 40 nm (1.0 wt.%) at T = 800 • C and T = 1000 • C. According to Ferrão et al (2022), the temporal evolution of the droplet size reduction for the pure HVO is in good agreement with D 2 -law. The classical liquid droplet combustion theory states that the normalized square diameter decreases linearly with time, with a nearly constant slope, defined as the burning rate.…”

“…Consequently, the nanofuel at T = 800 • C and T = 1000 • C does not follow the D 2 -law. To provide comparison results, the burning rate was analyzed until t/D 2 0 = 0.35 s/mm 2 , as previously mentioned by Ferrão et al (2022). The results suggest that pure HVO presents the lowest burning rate regardless of furnace temperature.…”

“…In the present work, a pure biofuel and nanofuel with a particle concentration of 1.0 wt.% were evaluated at two different temperatures in a drop tube furnace. Ferrão et al (2021) and Ferrão et al (2022) evaluated different particle sizes and concentration in a similar experimental arrangement. Consequently, the effect of adding nanoparticles to HVO in terms of droplet size evolution and burning rate has been studied.…”

“…The magnification lens is composed of a 6.5×Zoom, 12 mm FF, a 0.25×lens attachment, and a 2.0×short adapter with a magnifying range of 0.35-2.25, leading to an increase in the spatial resolution up to 8.2 µm/pixel. The image acquisition was pursued with 1000 fps with a resolution of 1200×500 pixels and an exposure time of 1/13000 s. This experimental technique was already employed in a previous study performed by Ferrão et al (2022). Moreover, a Photron FASTCAM mini UX50, a high-speed camera with 1.3 Megapixel, was used to acquire micro-explosions with more detail, and a high magnification lens was coupled to the camera.…”

“…Then, the bright spots provided from the micro-explosions were identified and counted by an algorithm developed in MATLAB. As reported by Ferrão et al (2022), to acquire the droplet size evolution during the combustion process, a region of interest (ROI) is defined. Then, the droplet outline is marked through the brightness gradient for these analyses, allowing the droplet characterization.…”