Dynamics of incipient carbon particle formation in a stabilized ethylene flame by in situ extended-small-angle- and wide-angle X-ray scattering

In-situ neutron imaging of hydrogenous fuels in combustion generated porous carbons under dynamic and steady state pressure conditions

“…Pictures (a) to (c) show a sequence of gradually zoomed measurements of the same probed soot region. (d) and (e) are examples from similar regions, where brighter very localized areas appear more distinctly and should indicate inner voids formed during the aggregation of sub-primary particles into primary particles that was evidenced from in-situ X-ray scattering measurements (see [6]) on the same flames used to produce the investigated sample. These pores are probably isolated from the gas phase and are in the micro-pore (D < 2 nm) region (IUPAC definition).…”

“…1 shows an overview of the basic elements of the setup. The neutron radiography detector, which can partially be seen in Fig.1a (Al window behind the cell), consists of a 6 LiF-ZnS scintillator with a charge coupled device (CCD) camera described in [17]. The neutron flux of the polychromatic beam with a peak neutron wavelength of 2.6 Å was on the order of 5 x 10 6 n s -1 cm 2 at the sample position.…”

“…The soot material was obtained by condensation of particles onto a steel plate in an ethylene diffusion flame according to the processes described in [6,7]. It was removed from the plate and stored for 7 years under atmospheric conditions.…”

“…Since X-ray attenuation is weaker for hydrogen than for carbon (for 10 keV radiation it as about 73 times), hydrogen detection can thus be three orders of magnitude more sensitive utilizing cold neutrons instead of hard X-rays. In practice, neutrons would be able to detect pressurized gaseous hydrogen surrounding carbon nanoparticles and thus be well-suited for the study of the interaction hydrogen and methane with carbon nanoparticle assemblies such as soot, the structure of which can be characterized by X-ray scattering techniques (see [5][6][7]9,11] and references therein).…”

“…It can also have positive aspects in that it may play an important role for clean energy conversion in combustion due to its material properties such as low density and fractal structure. In connection to our investigations on ethylene atmospheric pressure flames and soot condensation on metal plates utilizing in-situ X-ray scattering diagnostics [6][7][8][9], we obtained fractal-like (carbon) low-density soot materials (below 100 mg cm -3 ) [6,7]. This material showed considerable "thermal elasticity" with a density that changed by 30% between 300 and 600 K, approximately.…”