scholarly journals Roles of Unstable Chemical Species and Non-Equilibrium Reaction Routes on Properties of Reaction Product—A Review

2014 ◽  
Vol 2 (3) ◽  
pp. 182-205 ◽  
Author(s):  
Nobumitsu Shohoji
Keyword(s):  
Chemical Species ◽  
Equilibrium Reaction ◽  
Reaction Routes ◽  
Non Equilibrium

scholarly journals Shock interactions in inviscid air and $$\hbox {CO}_2$$–$$\hbox {N}_2$$ flows in thermochemical non-equilibrium

Shock Waves ◽  
2021 ◽  
Author(s):  
C. Garbacz ◽  
W. T. Maier ◽  
J. B. Scoggins ◽  
T. D. Economon ◽  
T. Magin ◽  
...  
Keyword(s):  
Chemical Species ◽  
High Energy ◽  
Ideal Gas ◽  
Shock Interaction ◽  
Interaction Patterns ◽  
Shock Interactions ◽  
Wave Interference ◽  
Type V ◽  
The Impact ◽  
Non Equilibrium

AbstractThe present study aims at providing insights into shock wave interference patterns in gas flows when a mixture different than air is considered. High-energy non-equilibrium flows of air and $$\hbox {CO}_2$$ CO 2 –$$\hbox {N}_2$$ N 2 over a double-wedge geometry are studied numerically. The impact of freestream temperature on the non-equilibrium shock interaction patterns is investigated by simulating two different sets of freestream conditions. To this purpose, the SU2 solver has been extended to account for the conservation of chemical species as well as multiple energies and coupled to the Mutation++ library (Multicomponent Thermodynamic And Transport properties for IONized gases in C++) that provides all the necessary thermochemical properties of the mixture and chemical species. An analysis of the shock interference patterns is presented with respect to the existing taxonomy of interactions. A comparison between calorically perfect ideal gas and non-equilibrium simulations confirms that non-equilibrium effects greatly influence the shock interaction patterns. When thermochemical relaxation is considered, a type VI interaction is obtained for the $$\hbox {CO}_2$$ CO 2 -dominated flow, for both freestream temperatures of 300 K and 1000 K; for air, a type V six-shock interaction and a type VI interaction are obtained, respectively. We conclude that the increase in freestream temperature has a large impact on the shock interaction pattern of the air flow, whereas for the $$\hbox {CO}_2$$ CO 2 –$$\hbox {N}_2$$ N 2 flow the pattern does not change.

Thermochemical Evaluation of Hydroxyl and Peroxyl Radical Precursors in the Formation of Tropospheric Ozone Reactions

2010 ◽  
Vol 3 ◽  
pp. 74-83
Author(s):  
G.O. Umosekhaimhe ◽  
S.E. Umukoro
Keyword(s):  
Particulate Matter ◽  
Tropospheric Ozone ◽  
Chemical Species ◽  
Basis Set ◽  
Enthalpies Of Formation ◽  
Ozone Formation ◽  
Complete Basis Set ◽  
Equilibrium Analyses ◽  
No2 Formation ◽  
Reaction Routes

The thermochemical properties of varieties of species needed to assess the most prominent pathways of tropospheric ozone transformation have been established. In the troposphere, ozone which is a secondary pollution produced by photochemical induced transformation, acts as an oxidizing agent to numerous atmospheric reactions leading to the formation of particulate matter. Based on the climate related problems resulting from the precursor of particulate matter, it is adequate to establish the feasible routes of ozone formation. In this study, the electronic structure methods which approximate the Schrödinger equation to compute Gibbs free energies and enthalpies of formation of the various chemical species participating in the reactions were used. These thermodynamic properties were determined using four computational model chemistry methods integrated in the Gaussian 03 (G03) chemistry package. Five known reaction pathways for the formation of NO2 (the O3 precursor specie), as well as the dominant ozone formation route from NO2 were examined and their energies determined. Of all the computational methods, the complete basis set (CBS-4M) method produced energies for all species of the five reaction routes. Out of the five routes, only the reactions involving radical species were favoured to completion over a temperature range of -100 and +100oC. The most relevant reaction route for the formation of NO2 and subsequently O3 is that involving the peroxyl acetyl nitrate (PAN) and hydroxyl radicals. Chemical equilibrium analyses of the reaction routes also indicated that reduction in temperature encourages NO2 formation while increase in temperature favours O3 production.

scholarly journals Ammonia Synthesis via Non-Equilibrium Reaction of Lithium Nitride in Hydrogen Flow Condition

2013 ◽  
Vol 77 (12) ◽  
pp. 580-584
Author(s):  
Kiyotaka Goshome ◽  
Hiroki Miyaoka ◽  
Tomoyuki Ichikawa ◽  
Takayuki Ichikawa ◽  
Yoshitsugu Kojima
Keyword(s):  
Flow Condition ◽  
Ammonia Synthesis ◽  
Lithium Nitride ◽  
Hydrogen Flow ◽  
Equilibrium Reaction ◽  
Non Equilibrium

DSMC Predictions of Non-equilibrium Reaction Rates

2011 ◽  
Author(s):  
R. B. Bond ◽  
M. A. Gallis ◽  
J. R. Torczynski
Keyword(s):  
Reaction Rates ◽  
Equilibrium Reaction ◽  
Non Equilibrium

Modeling of Combustion of Mono-Carbon Fuels Using the Rate-Controlled Constrained-Equilibrium Method

2004 ◽  
Author(s):  
Sergio Ugarte ◽  
Mohamad Metghalchi ◽  
James C. Keck
Keyword(s):  
Combustion Process ◽  
Chemical Species ◽  
Second Law Of Thermodynamics ◽  
Equilibrium System ◽  
Equilibrium Method ◽  
Ignition Delay Times ◽  
Constrained Equilibrium ◽  
Rate Controlled ◽  
Induction Times ◽  
Non Equilibrium

Modeling of a non-equilibrium combustion process involves the solution of large systems of differential equations with as many equations as species present during the process. The process of chemical reaction and combustion is complicated since it may be governed by hundreds, sometimes thousands of microscopic rate processes. Integration of these equations simultaneously becomes more difficult with the complexity of the combustible. In order to reduce the size of these systems of equations, the Rate-Controlled Constrained-Equilibrium method (RCCE) has been proposed to model non-equilibrium combustion processes. This method is based on the Second Law of Thermodynamics, assuming that the evolution of a complex system can be described by a small number of rate-controlling reactions which impose slowly changing constraints on all allowed states of the system, therefore a non-equilibrium system will relax to its final equilibrium state through a sequence of rate controlled constrained equilibrium states. Oxidation induction times and concentration of species during a combustion process are found in a less complicated way with this method, as equations for constraints rather than for species determine the composition and evolution of the system. The time evolution of the system can be reduced since the number of constraints is much smaller than the number of species presents, so the number of equations to solve. The RCCE method has been applied to the stoichiometric combustion of mono-carbon fuels using 29 chemical species and 139 chemical reactions at different sets of pressure and temperature, ranging from 1 atm to 100 atm, and from 900 K to 1600 K respectively. Results of using 8, 9, 10 and 11 constraints compared very well to those of the detailed calculations at all conditions for the cases of formaldehyde (H2CO), methanol (CH3OH) and methane (CH4). For these systems, ignition delay times and major species concentrations were within 5% of the values given by detailed calculations, and computational saving times up to 50% have been met.

Study of Thermo-Chemical Non-Equilibrium Phenomena behind Strong Shock Waves at Atmospheric Reentry

2011 ◽  
Vol 274 ◽  
pp. 13-22 ◽  
Author(s):  
R. Allouche ◽  
R. Haoui ◽  
J.D. Parisse ◽  
R. Renane
Keyword(s):  
Numerical Simulation ◽  
Equilibrium State ◽  
Chemical Species ◽  
Strong Shock ◽  
One Dimensional ◽  
Atmospheric Reentry ◽  
High Enthalpy ◽  
Finite Differences Method ◽  
Strong Shock Waves ◽  
Non Equilibrium

This work consists of the numerical simulation of high enthalpy flows. The numerical model is governed by Euler equations and supplemented by the equations of the chemical kinetics modeling the phenomena of the chemical air components in a non-equilibrium state. The finite differences method is used for numerical simulations, the phenomena of a hypersonic flow one-dimensional reactive, non-viscous, chemical non-equilibrium is developed taking into account the physicochemical phenomena like the vibration, the dissociation of the diatomic molecules, the ionization of molecules and the formed atoms of chemical species to higher temperatures which appear behind a strong shock detached and evolve according to time in a relaxation range until to reach the equilibrium state. We are interesting in particular on the temperature effect in ionization of the atoms and the molecules.

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