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Title: Trapping and aerogelation of nanoparticles in negative gravity hydrocarbon flames

We report the experimental realization of continuous carbon aerogel production using a flame aerosol reactor by operating it in negative gravity (−g; up-side-down configuration). Buoyancy opposes the fuel and air flow forces in −g, which eliminates convectional outflow of nanoparticles from the flame and traps them in a distinctive non-tipping, flicker-free, cylindrical flame body, where they grow to millimeter-size aerogel particles and gravitationally fall out. Computational fluid dynamics simulations show that a closed-loop recirculation zone is set up in −g flames, which reduces the time to gel for nanoparticles by ≈10{sup 6} s, compared to positive gravity (upward rising) flames. Our results open up new possibilities of one-step gas-phase synthesis of a wide variety of aerogels on an industrial scale.
Authors:
 [1] ;  [2] ;  [3] ;  [2] ; ;  [4] ;  [5] ;  [6]
  1. Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, Missouri 63130 (United States)
  2. (United States)
  3. Department of Mechanical Engineering, University of Washington, Seattle, Washington 98195 (United States)
  4. Laboratory for Aerosol Science, Spectroscopy, and Optics, Desert Research Institute, Nevada System of Higher Education, Reno, Nevada 89512 (United States)
  5. Condensed Matter Laboratory, Department of Physics, Kansas State University, Manhattan, Kansas 66506 (United States)
  6. TSI Incorporated, 500 Cardigan Rd, Shoreview, Minnesota 55126 (United States)
Publication Date:
OSTI Identifier:
22299913
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 104; Journal Issue: 24; Other Information: (c) 2014 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 77 NANOSCIENCE AND NANOTECHNOLOGY; AEROSOLS; AIR FLOW; CARBON; COMPUTERIZED SIMULATION; CYLINDRICAL CONFIGURATION; FLAMES; FLUID MECHANICS; GRAVITATION; HYDROCARBONS; SYNTHESIS; TRAPPING NANOPARTICLES