Combustion Enhancement of Liquid Fuels via Nanoparticle Additions

ABSTRACT: Addition of nano-sized energetic particles to liquid fuel (e.g., JP-8 or RP-1) offers the possibility of increasing energy density, while maintaining or improving ignition characteristics of the bulk fuel. When used in stable dispersions of small percentages of additives, only limited physical changes to existing combustion systems may be required. The culmination of a) increases in widespread availability and affordability of a large variety of nano-sized particles, b) understanding of nano-sized particle ignition and combustion, and c) advances in colloidal science of nano-sized particle/liquid suspensions, now allows for development of enhanced nanofluid fuels. Overall objectives of the proposed Phase I effort are development and evaluation of several candidate nanofluid fuels using RP-1 as a representative liquid propulsion fuel. Our approach includes: 1) Develop stable colloidal systems using techniques such as metal-ligand stabilization, polymer coating for controlling zeta potential, surfactant addition, etc. Commercially available energetic particles will be selected based upon volumetric heating rates, density, average agglomeration number, etc. 2) Characterize ignition behavior of nanofluids using single droplet experiments for examining the effect of additive type, particle size, oxide layer thickness, dispersant material, etc. 3) Examine spray combustion characteristics of select nanofluid fuels through a co-axial injector with a gaseous oxidizer. BENEFIT: This SBIR effort will successfully demonstrate the use of nanofluid fuels in liquid rocket engines and open up a market for these nanofluid fuels in liquid propulsion systems. The nanofluid fuels are particularly attractive for volume-limited systems. By introducing energetic nano-particles to the fuel, density-Isp of liquid propulsion systems can be significantly increased to levels approaching those of solid-propellant rockets. Development of an efficient distribution method, such as a highly concentrated colloidal suspension that can be added to bulk fuel, will ease the integration of the new enhanced-performance nanofuel into the existing fuel distribution infrastructure. Alternatively, an injection system could be installed in line with existing fuel tank filling equipment so that the concentrated suspension would be added to the fuel at a metered rate. This nanofuel technology could be extended to direct-injection internal combustion engines for all kinds of applications.