Physical properties and spray pattern of tailored fuels: Liquid fuels containing suspended nanoparticles.

摘要

Physical properties such as density, viscosity and colloidal stability, and spray pattern of tailored fuels (ethanol and n-decane containing 20-30nm aluminum oxide) are investigated. Density is determined using a simple fixed volume experiment and is found to increases linearly with the percentage of nanoparticles by mass in the suspension. Viscosity of ethanol and its suspensions is determined using a rotational rheometer. Viscosity shear rate relationship shows that with increase in particle concentration, the viscosity of the suspension increases. It was also observed that suspension with 5% or higher particle concentrations showed shear thinning behavior, deviating from the Newtonian behavior of pure solvents such as ethanol. Ethanol and n-decane/Span80 (surfactant) suspensions showed good colloidal stability for up to 10-12 minutes with very little sedimentation for low particle concentrations of up to 5%. Pure n-decane suspensions did not maintain stability for more than 5 seconds and immediate sedimentation was observed. 5% aluminum oxide and n-Decane/span80 suspensions did not clog the 267microm orifice nozzle after 10 minutes of operation with a nitrogen driven fuel supply system operating at 50-80psi pressure. Ethanol suspensions (without surfactant) with 5% aluminum oxide clogged the nozzle after ~5 minutes of operation. Both fuels carried lower percentage of particles (1-4%) well through the nozzle causing no clogging for a 10-12minute operation time. A SETScan OP-200 patternator is used to characterize the spray. Results show that particle addition of up to 4% nanoparticles has little effect on spray angle and the spray pattern. However, as the particle concentration is increased the total surface area of the spray is slightly reduced. To study the spray combustion, a vitiated coflow spray burner was designed and built. The air and coflow fuel supply systems will be finalized in the near future.