Aerolization During Boron Nanoparticle Multi-Component Fuel Group Burning Studies.

摘要

A complement to the development of new fuels to meet future energy demands of the U.S. Navy is the enhancement of energy density of existing fuels, thus increasing system payloads, ranges, and/or performance. Addition of energetic solid phase materials, such as boron, magnesium, or aluminum, to liquid hydrocarbon-based fuels can potentially increase energy density. Previous studies investigating the effect of energetic metal addition to liquid hydrocarbon-based fuels have produced mixed results. Boron has excellent potential as a liquid fuel additive due to its high volumetric and gravimetric heating value. Boron carbide (B4C) is widely available due to its commercial application as an abrasive. Boron particles were first tested as fuel additives in the 1950s to 1970s during rocket development and found to significantly increase fuel energy density but boron slurry combustion has problems with ignition, flame stability, and burnout. Recent advances in nanotechnology may allow for high-volume production of boron nanoparticles coated with catalysts and organics to enhance and control combustion, promote suspension and dispersion in fuel, and inhibit premature oxidation. Controlled studies on the effect of boron nanoparticle addition on fuel aerosol droplet size during group burning experiments were conducted by the U.S. Naval Research Laboratory (NRL Code 6114) and the Hawaii Natural Energy Institute (HNEI) at the University of Hawaii (UH) from 2009 to 2011. These studies were performed using a benchtop fuel burner assembly system with a Phase-Doppler-Particle Analyzer (PDPA) to investigate the effect of specific nanoparticle addition (boron, CeO2-coated boron, and CeO2) on aerosol droplet size and velocity in a JP-5 carrier fuel. Results of this study showed little to no effect of boron nanoparticle addition (approximately 2.5% weight loading) on aerosol droplet size and velocity distribution fields in the wet, or no flame, condition. Results did suggest an effect of boron nanoparticle addition in the flame case. Rate of change in average droplet diameter with distance from the flame base was greater in the presence of boron nanoparticles, suggesting enhanced combustion and increased droplet evaporation in the JP-5 carrier fuel. Additionally, there was a measureable increase in average droplet velocity near the flame base. However, the opposite effect was seen when reduced CeO2 was used as a catalysts or catalyst only was added to JP-5, suggesting combustion was inhibited.