MUTUAL SENSITIZATION OF THE OXIDATION NO AND AMMONIA: EXPERIMENTAL AND KINETIC MODELING

International audienceThe selective non-catalytic reduction of NO by ammonia (SNCR) has been extensively studied. Recent experiments performed in a jet-stirred reactor (JSR) at atmospheric pressure for various equivalence ratios (0.1-2) and initial concentrations of NH 3 (500 to 1000 ppm) and NO (0 to 1000 ppm) revealed kinetic interactions similar to mutual oxidation sensitization of hydrocarbons and NO. The experiments were performed at fixed residence times of 100 and 200 ms, and variable temperature ranging from 1100 to 1450 K. Kinetic reaction mechanisms were used to simulate these experiments. According to the most reliable model, the mutual sensitization of the oxidation of ammonia and nitric oxide proceeds through several reaction pathways leading to OH production, mainly responsible for ammonia oxidation in the current conditions: NH 2 +NO → NNH+OH, NNH → N 2 +H, NNH+O 2 → N 2 +HO 2 , H+O 2 → OH+O, H+O 2 +M → HO 2 +M, and NO+HO 2 → NO 2 +OH. Introduction Thermal de-NO, also called selective non-catalytic reduction of NO by ammonia (SNCR), is a common NO reduction technique which is efficient in a small temperature range centered around 1200-1250 K. Many experimental and modeling studies concern SNCR [1-5]. However, existing kinetic models show weaknesses and sometimes fail to represent the kinetics of ammonia oxidation [6] whereas interest for this fuel is growing. Nowadays, ammonia is viewed as an alternative zero-carbon fuel which presents potential for future power stations [6]. In this context, ammonia combustion in a gas turbine was recently demonstrated in Japan [7]. However, its combustion needs further studies [6] and kinetic interpretation needs further investigations. Therefore, experiments were performed in a JSR at atmospheric pressure for various equivalence ratios (0.1-2), for several initial concentrations of NH 3 and NO, at fixed residence times and variable temperature. Kinetic modeling was used to interpret the results and delineate reaction pathways

Ignition Delay Times of Kerosene (Jet-A)/Air Mixtures

Ignition of Jet-A/air mixtures was studied behind reflected shock waves. Heating of shock tube at temperature of 150 C was used to prepare a homogeneous fuel mixture. Ignition delay times were measured from OH emission at 309 nm and from absorption of He-Ne laser radiation at 3.3922 micrometers. The conditions behind shock waves were calculated by one-dimensional shock wave theory from initial conditions T1, P1, mixture composition and incident shock wave velocity. The ignition delay times were obtained at two fixed pressures 10, 20 atm for lean, stoichiometric and rich mixtures (ER=0.5, 1, 2) at an overall temperature range of 1040-1380 K.Comment: V.P. Zhukov, V.A. Sechenov, and A.Yu. Starikovskii, Ignition Delay Times of Kerosene(Jet-A)/Air Mixtures, 31st Symposium on Combustion, Heidelberg, Germany, August 6-11, 200

Wide range modeling study of dimethyl ether oxidation

A detailed chemical kinetic model has been used to study dimethyl ether (DME) oxidation over a wide range of conditions. Experimental results obtained in a jet-stirred reactor (JSR) at I and 10 atm, 0.2 < 0 < 2.5, and 800 < T < 1300 K were modeled, in addition to those generated in a shock tube at 13 and 40 bar, 0 = 1.0 and 650 :5 T :5 1300 K. The JSR results are particularly valuable as they include concentration profiles of reactants, intermediates and products pertinent to the oxidation of DME. These data test the Idnetic model severely, as it must be able to predict the correct distribution and concentrations of intermediate and final products formed in the oxidation process. Additionally, the shock tube results are very useful, as they were taken at low temperatures and at high pressures, and thus undergo negative temperature dependence (NTC) behavior. This behavior is characteristic of the oxidation of saturated hydrocarbon fuels, (e.g. the primary reference fuels, n-heptane and iso- octane) under similar conditions. The numerical model consists of 78 chemical species and 336 chemical reactions. The thermodynamic properties of unknown species pertaining to DME oxidation were calculated using THERM

Experimental and kinetic study on ignition delay times of methane/hydrogen/oxygen/nitrogen mixtures by shock tube

This study aims (1) to analyze the performances among regencies/ cities in Jambi Province, and (2) to categorize the regencies/ cities in Jambi Province based on economic, human resources, and infrastructure development performances. Datas used in this study are secondary data of 2009-2012 from Statistics Indonesia, consists of eight component indicators to assess the performance of economic development, the five component indicators to assess the performance of the components of human resources development, and eight component indicators to assess the performance of infrastructure development. The analytical method used to achieve the objectives of the first research purposes is principal component analysis (PCA) which followed by factor analysis and to achieve the third purpose is cluster analysis. The results showed that (1) Jambi City is ranked first in the overall development performance, followed by of Tanjab Barat and Batang Hari Regencies, (2) four clusters of regencies/ cities in Jambi Province are formed based on the performance of development, namely: cluster I (Kerinci, Merangin, and Tebo Regencies) have lower performance of regional development, cluster II (Tanjab Timur Regency) has average to high performance of regional development, cluster III (Sarolangun, Batang Hari, Muaro Jambi, Tanjab Barat, Bungo Regencies, and Sungai Penuh City) have average performance of regional development, and cluster IV (Jambi City) has high performance of regional development

An experimental and kinetic modelling study of the oxidation of the four isomers of butanol

Butanol, an alcohol which can be produced from biomass sources, has received recent interest as an alternative to gasoline for use in spark ignition engines and as a possible blending compound with fossil diesel or biodiesel. Therefore, the autoignition of the four isomers of butanol (1-butanol, 2-butanol, iso-butanol, and tert-butanol) has been experimentally studied at high temperatures in a shock tube and a kinetic mechanism for description of their high-temperature oxidation has been developed. Ignition delay times for butanol/oxygen/argon mixtures have been measured behind reflected shock waves at temperatures and pressures ranging from approximately 1200 to 1800 K and 1 to 4 bar. Electronically excited OH emission and pressure measurements were used to determine ignition delay times. A detailed kinetic mechanism has been developed to describe the oxidation of the butanol isomers and validated by comparison to the shock tube measurements. Reaction flux and sensitivity analysis indicate that the consumption of 1 butanol and iso-butanol, the most reactive isomers, takes place primarily by H-atom abstraction resulting in the formation of radicals, the decomposition of which yields highly reactive branching agents, H-atoms and OH radicals. Conversely, the consumption of tert butanol and 2-butanol, the least reactive isomers, takes place primarily via dehydration, resulting in the formation of alkenes, which lead to resonance stabilized radicals with very low reactivity. To our knowledge, the ignition delay measurements and oxidation mechanism presented here for 2-butanol, iso-butanol, and tert butanol are the first of their kind.