High-throughput Generation of Aircraft-like Soot

GEORGIOS A. KELESIDIS, Una Trivanovic, Sotiris Pratsinis, ETH Zurich, Switzerland

     Abstract Number: 188
     Working Group: Combustion

Abstract
High-throughput, laboratory units for generation of aircraft-like soot are needed to quantify and understand the impact of such emissions on public health and climate change due to the high costs and limited access to aircraft engines. Flame spray pyrolysis [1] is used here to generate high soot concentrations, up to 255 mg/m³, three orders of magnitude higher than those typically obtained by widely-used soot generators, such as premixed flame reactors [2]. This enables routine characterization of the soot specific surface area (SSA) and pore size distribution by N₂ adsorption. The geometric mean mobility diameter, d_m, of soot agglomerates was systematically varied from 15 to 180 nm by varying the equivalence ratio (EQR) at constant fuel feed rate. The geometric mean primary particle diameter, d_p, standard deviation, σ_gp, and mass-mobility exponent, D_fm, were hardly altered in that EQR range. These measured D_fm and σ_gp indicate that soot primary particles were sinter-bonded by surface growth [3], in agreement with power laws derived by discrete element modeling [4]. The organic to total carbon mass ratio of soot produced here is consistently small (< 20%) regardless of EQR. Most importantly, soot made at EQR ≤ 1.34 has mainly small pores (< 2.5 nm) and similar morphology (D_fm= 2.52 ± 0.17), SSA (160 - 239 m²/g), d_m (15 - 60 nm) and d_p (14 nm) with those from high thrust aircraft emissions.

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