Modeling of sulfur gases and chemiions in aircraft engines

Abstract

The formation of sulfur-containing gases and chemiions in the combustor and their evolution in the turbine of aircraft-engines between combustor exit and engine exit are computed including the conversion fraction of fuel sulfur into SO 3 and H 2 SO 4. The combustion is approximated by an adiabatic time-dependent box-model. The temperature and pressure evolution in the flow between combustor exit and engine exit is modeled using a quasi one-dimensional (Q1D) model. New kinetic models for S-containing gases and chemiions are used. About 1% of the sulfur molecules are computed to be converted into SO 3 within the combustor and about 10% into SO 3 and H 2 SO 4 before engine exit. Box models agree with the Q1D results for the same initial and thermodynamic conditions, but underestimate sulfur conversion by a factor of 3 if using a linear temperature profile. The number of positive and negative ions formed within the combustor, mainly NO + and HSO − 4 , depends strongly on the fuel/air ratio and on recombination reactions, mainly with C 2 H 3 O + ions. The model computes a total ion emission of 2•10 15 per kg of fuel burned at cruise. Far larger ion concentrations close to values observed behind engines at ground, are computed for higher combustor inlet pressure and higher fuel/air ratio.  2002 Éditions scientifiques et médicales Elsevier SAS. All rights reserved. Zusammenfassung Die Bildung von schwefelhaltigen Gasen und Chemi-Ionen in der Brennkammer von Flugzeugtriebwerken und ihre Veränderung in der Turbine zwischen Brennkammer und Treibwerksaustritt werden berechnet, einschließlich der Umwandlung von Treibstoff-Schwefel in SO 3 und H 2 SO 4. Die Verbrennung wird mit einem adiabatischen instationären Box-Modell approximiert. Das Temperatur-und Druck-Profil entlang der Strömung vom Brennkammer-Austritt bis Triebwerks-Austritt werden mit einem quasi-eindimensionalen (Q1D) Strömungs-Model berechnet. Für die Kinetik der S-haltigen Gase und der Chemi-Ionen werden neue Modelle benutzt. Etwa 1% der Schwefelmoleküle werden in der Brennkammer in SO 3 und etwa 10% in der Turbine in SO 3 und H 2 SO 4 umgewandelt. Für gleiche thermodynamische Bedingungen liefern Box-Modelle gleiche Ergebnisse, unterschätzen aber die Umwandlung um einen Faktor 3, wenn das Temperaturprofil in der Turbine durch ein lineares Profil approximiert wird. Die Zahl der positiven and negativen Ionen, die in der Brennkammer gebildet werden, vorwiegend NO + and HSO − 4 , hängt stark vom Treibstoff/Luft-Verhältnis und den Rekombinations-Reaktionen, vorwiegend mit C 2 H 3 O + Ionen, ab. Im Modell werden insgesamt 2•10 15 Ionen pro kg verbrannten Treibstoffs unter Reiseflugbedingengen emittiert. Sehr viel größere Konzentrationen, wie am Boden hinter Triebwerken gemessen, werden für höhere Brennkammerdrücke und Brennstoff/Luft-Verhältnisse berechnet.  2002 Éditions scientifiques et médicales Elsevier SAS. All rights reserved.

In-situ observations of young contrails – overview and selected results from the CONCERT campaign

“…This fraction can be regarded as a lower limit because our method accounts specifically for the OH-induced conversion of SO 2 . This lower limit is in good agreement with recent model simulations of the sulfur conversion efficiency (Starik et al, 2002), and compares well with former direct in-situ measurements of total sulfuric acid (Curtius et al, 2002) in aircraft exhaust plumes. The uncertainty of the method arises from the uncertainty of the effective rate coefficients for the reaction SO 2 + OH and NO + OH.…”

Ab intio Investigation of the Thermochemistry and Kinetics of the SO2 + O3− → SO3− + O2 Reaction in Aircraft Engines and the Environment

“…The SO2 conversion into sulfuric acid in the Earth's atmopshere includes two stages [16,[24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42]. The first stage is the sulfur dioxide oxidation to sulfur trioxide [16,[24][25][26][27][28][29][30][31][32][33][34][35][36].…”

“…The first stage is the sulfur dioxide oxidation to sulfur trioxide [16,[24][25][26][27][28][29][30][31][32][33][34][35][36]. The second stage is the sulfur trioxide hydrolysis to sulfuric acid [37][38][39][40][41][42].…”

“…The second stage is the sulfur trioxide hydrolysis to sulfuric acid [37][38][39][40][41][42]. The conversion of SO2 into SO3 and H2SO4 has been investigated using experimental and theoretical methods in the past [16,[24][25][26][27][28][29][30][31][32][33][34][35][36]. For example, the reviews of experiments relevant to the gas-phase conversion SO2 into the sulfuric acid has been presented in [16,30].…”

“…For example, the reviews of experiments relevant to the gas-phase conversion SO2 into the sulfuric acid has been presented in [16,30]. Starik with co-workers have investigated the concentrations of sulfate aerosol precursors and chemiions in the aircraft engines using advanced numerical models [34]. Ozone injection methods used to simultaneously remove NOx and SO2 in the flue gas have been investigated by Mok and Lee [35,36].…”