Investigation on spray and combustion characteristics of boron/ethanol nanofuel utilizing 50 kHz repetition rate high-speed laser measurements

摘要

Over the last decades, researchers devote to improving the combustion and emission performance of conventional fuels. Nanofuels, which are suspensions of energetic nanomaterials in liquid media, was proposed and became a promising alternative fuel. Optimizing the blend of nanoparticles and hydrocarbon fuels can dramatically decrease the world's demand for fossil fuels without modifying state-of-the-art engines, and it can also significantly reduce pollutant emissions. However, our knowledge about nanofuels remains limited. Here, we experimentally investigated the spray and combustion characteristics of boron/ethanol nanofuels. We explore the effects of the size and the doping concentration of boron particles on suspension quality and the corresponding spray and combustion behavior. The nanofuels were prepared using boron particles, 100 nm and 400 nm in diameter, at particle loading concentration of 0.5 wt% and 1.0 wt%, respectively. The spray flame was operated on a modified McKenna burner using a coaxial air-assisted atomization method. The burner features a retractable fuel capillary injector, and the influence of capillary recess length on spray flames was studied in this work. Mie scattering was applied to investigate the spray characteristics of the ethanol and boron/ethanol nanofuels in non-reacting and reacting flows. Chemiluminescence was adopted to study the heat release of the target flames and the ignition delay of the boron particles during combustion. High-speed measurements offer us an opportunity to investigate the instantaneous phenomena during spray and combustion, and thus Mie scattering and chemiluminescence were operated at 50 kHz in our study.