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Modeling Ozone Decomposition Flames Alexander A. KONNOV Energy Fuels, Just Accepted Manuscript • Publication Date (Web): 12 Nov 2012 Downloaded from http://pubs.acs.org on November 19, 2012

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Modeling Ozone Decomposition Flames

A. A. Konnov Division of Combustion Physics, Lund University, Lund, Sweden

Author:

Alexander A. Konnov

Division of Combustion Physics, Lund University P.O. Box 118, S-221 00, Lund, Sweden

Email: [email protected]

1 ACS Paragon Plus Environment

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Abstract

An updated detailed kinetic mechanism for ozone combustion is developed.

The

contemporary choice of the reaction rate constants is presented with emphasis on their uncertainties. Model predictions are compared with available experimental data for ozone decomposition flames and with the MSU mechanism used elsewhere in the literature. These two models show similar performance in calculating laminar burning velocities, yet predict largely different concentration profiles of singlet oxygen, O2(a¹∆g).

The necessity for

consideration of all reactions included in the mechanism as reversible is emphasized.

Keywords: ozone, burning velocity, kinetic mechanism, singlet oxygen


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Introduction

Ozone can easily be generated on-line using, e.g. dielectric barrier discharge, and directly used for combustion enhancement.

Potentially this approach opens up the interesting

possibility to modify mixture reactivity without changing the equivalence ratio or mass flow into a combustion device. Nomaguchi and Koda

1

studied spark ignition of methane and

methanol in ozonized air; they also measured the influence of O3 on the burning velocity of methane + air flames on a nozzle burner and observed its relative increase by 4-6 %. Tachibana et al.

2

investigated the effect of ozone addition in compression ignition engines

and interpreted it in terms of increase of cetane number by 2 to 4 for 500 ppm of O3. Magzumov et al. 3 predicted a shortening of the detonation induction zone length due to small addition of ozone into hydrogen + air mixtures. Nishida and Tachibana 4 demonstrated that ozone addition could be helpful in control of ignition timing in HCCI engines. For the same purpose Schonborn et al.

5

attempted alteration of the fuel structure via its reaction with

ozone prior to combustion.

Ombrello et al.

6

investigated lifted diffusion flames of propane and reported combustion

enhancement due to ozone. Using detailed kinetic modeling they performed computations of laminar burning velocity and demonstrated that flame acceleration is caused by chemical reactions, not by thermal effects of ozone decomposition. Most recently Halter et al.

7

and

Wang et al. 8 obtained new experimental results on increase of the laminar burning velocity of methane + air flames with ozone admixture using Bunsen burner and heat flux flat flames respectively.

Detailed kinetic modeling was found in good agreement with these

experiments. It is remarkable that in both works

7, 8

two essentially identical mechanisms

have been compiled based on the GRI-mech. 3.0 and ozone reaction subset taken from


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Ombrello et al.

6

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with some additional reactions and removal of duplicated reactions. The

model of Ombrello et al. 6, in turn, was based on the recommendations of Ibraguimova et al. 9 and on the model of Smekhov et al.

10

developed for simulating ignition of hydrogen +

oxygen mixtures with electronically excited species. This model was similarly used by Bourig et al. 11 in the modeling of hydrogen + oxygen flames.

Rate constants used in the above-mentioned mechanisms were often taken from atmospheric chemistry studies or evaluated based on empirical rules. Moreover, none of these models was tested in comparison with the simplest flames of ozone decomposition. The goal of the present work was therefore to evaluate the reliability and the accuracy of the rate constants pertinent to ozone decomposition, and to validate and analyze kinetic mechanism predictions at high temperatures.

Species and thermodynamic data It was established long time ago, e.g. by Hirschfelder et al.

12

, that the mechanism of ozone

decomposition is governed by 3 reactions O2+O+M=O3+M

(1)

O3+O= O2+ O2

(2)

O+O+M=O2+M

(3)

In practice, however, dielectric barrier discharge generates not only ozone, but also excited atomic oxygen O(1D), and excited singlet states of oxygen: O2(a¹∆g) and O2(b¹Σg+). Depending on the distance from ozone generator to combustion zone, pressure and gas composition, excited species may survive or not 6, 13. The O2(b¹Σg+)-state is very short lived and relaxes quickly to the lowest lying excited state, O2(a¹∆g). It was therefore not included


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in the present mechanism; in the following the O2(a¹∆g)-state is referred to as singlet oxygen. The triplet ground state of oxygen, O2(X³Σg-), is always termed O2.

Thermodynamic data were all taken from the recent database of Goos et al 14. All reactions in the mechanism are reversible. Rate constants of the reverse reactions are calculated from the forward rate constant and thermodynamic data. Transport properties of excited species were assumed equal to those of corresponding ground-state species.

Reactions In the following a detailed description of the ozone mechanism is given; all reactions included are listed in Table 1.

In the recent mechanisms

6, 7, 8, 11

reactions of ozone

decomposition and recombination of O2 and O forming ozone were written as irreversible with different rate constants for different collisional partners.

These rate constants

recommended by Ibraguimova et al. 9 were originally proposed by Makarov and Shatalov 15. Significant progress in understanding of ozone thermal dissociation has been made since then as summarized by Luther et al. 16. To cover an extended range of temperatures both energy transfer and radical complex mechanisms were taken into account for the reversible reaction O2+O+M= O3+M

(1).

For the high-temperature component of the reaction rate, the collisional efficiency for O2 was scaled compared to N2 using measurements of Endo et al.

17

at 800 K.

For the low-

temperature component O2 is a slightly more efficient collisional partner as compared to N2 18

. Collisional efficiency of O3 was assumed 2.5-3 times higher than that of O2 15, while for

O atoms it is probably 4-5 times higher. The uncertainty of the theoretical approximations 16 was not quantified, yet the rate constants at room temperature are very well established 18. At


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higher temperatures the uncertainty factor was evaluated to be 1.2, see Table 1, that is rate constants could be 20 % higher or lower.

The rate constant of reaction O3+O= O2+ O2

(2)

is well established for atmospheric conditions. Atkinson et al.

18

provided recommendation

up to 400 K, which is adopted here. This rate constant is also in good agreement with the measurements up to 500 K

19

, extrapolation to higher temperatures could be less accurate.

Starik and Titova 20 included in their kinetic schemes the irreversible reaction O2(1∆)+ O2=> O3+O

(-2b)

with an estimated rate constant k = 1.2E+13 exp (-39604/T) cm3/mol s. If this reaction is included in the model as reversible then the calculated reverse rate of singlet oxygen formation rapidly approaches the rate of formation of the ground state oxygen at flame temperatures. In the present mechanism this reaction is taken into account as the second channel of reaction (2) between ozone and atomic oxygen with the rate constant proposed by 21

Vasiljeva et al. Steinfeld et al.

. Note that the rate expression used here follows recommendations of

22

based on the upper limit experiments of Gauthier and Snelling

23

. In the

absence of direct proof of existence and role of channel (2b), its rate is highly uncertain.

The choice of the rate constant of reaction O+O+M= O2+M

(3)

was described elsewhere 24, since then no new measurements have appeared in the literature. In the present model the collisional efficiency of O3 is assumed equal to that of O2 following recommendations of Baulch et al. 25. Starik and Titova

20

included in their kinetic schemes

the irreversible reaction


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O2(1∆)+M=>O+O+M

(-3b)

with an estimated rate constant k = 2.6E+18 exp (-48188/T) cm3/mol s. If this reaction is included in the model as reversible, the calculated reverse rate of singlet oxygen formation is higher than that of the ground state oxygen at flame temperatures, which has no experimental justification. In the present mechanism this reaction is taken into account as the second channel of reaction (3). Vasiljeva et al. 21 suggested that 10% of oxygen formed is in singlet state via channel (3b), which is considered in the recalculation of the original rate constant from Warnatz 26. In the absence of direct proof of existence and the role of channel (3b) its rate is highly uncertain.

Recommendations of Atkinson et al. 18 were adopted for singlet oxygen quenching by O2. O2(1∆)+M= O2+M

(4)

The same temperature dependence was assumed for N2 and Ar as collision partners. Collisional efficiencies of Ar 21 and N2 are very small compared to O2. The rate of quenching by O2 at room temperature is about 1E+6 cm3/mol s

18

. Collisional quenching by O is

difficult to isolate experimentally, yet Cupitt et al. 27 suggested the rate of 4.2E+8 for M = O. This reaction channel is included in the model separately to evaluate its role and potential impact. Ibraguimova et al. 9 suggested rate constant of 2.4E+9 for singlet oxygen quenching by O3. This channel is not included in the model since it mimics reaction O2(1∆)+ O3= O2+ O2+O

(6)

producing molecular and atomic oxygen instead of ozone. The recommendation of Atkinson et al. 18 was adopted for reaction (6).

The process of three-body deactivation of singlet oxygen O2(1∆)+O+M=O+ O2+M

(5)


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was proposed

28

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to explain the rapid decrease of O2(1∆) generation efficiency in a gas

discharge with increasing oxygen pressure. A rate constant of 3.6E+15 cm6/mol2 s was suggested 21, 28. Experiments with laser photolysis of ozone indicated much higher value (by an order of magnitude) 29, yet the authors admitted that other species may be involved in the quenching observed. The rate constant of Braginskiy et al. high uncertainty.

Starik and Titova

20

28

is therefore adopted here with

suggested the reversible reaction O2(1∆)+O+M=

O3+M with the rate constants of direct and reverse reactions close to those of ground-state oxygen recombination with O atoms. Formation of significant amounts of singlet oxygen during ozone dissociation has no experimental evidence and therefore this reaction has not been considered in the present model.

Excited atomic oxygen O(1D) will hardly survive between ozone generator and combustion zone, yet pertinent reactions are included in the model for completeness. It will be shown in the following that O(1D) is formed in small quantities in ozone decomposition flames and participates in singlet oxygen recycling.

No experimental evidence was found in the literature for reaction O(1D)+ O2(1∆)=O+ O2

(7).

It is tentatively included in the model with the rate constant estimated by Doroshenko et al. 30.

Interaction of excited oxygen atoms with molecular oxygen includes 3 channels: quenching O(1D)+ O2=O+ O2

(8b)

and energy transfer to O2 with formation of electronically excited O2(a¹∆g) (with branching ratio of 5%) or O2(b¹Σg+) (80% at room temperature) 18. Since O2(b¹Σg+) excited state is not


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considered in the model due to rapid quenching into O2(a¹∆g), the reaction rate (85% of the total recommended 18) is attributed to the formation of O2(a¹∆g) in reaction O(1D)+ O2=O+ O2(1∆)

(8a).

Physical quenching in reaction (8b) is then 15% or much less at 298 K (due to ±10% uncertainty of the branching ratio for reaction (8a) 18), which makes this rate constant highly uncertain. One should note that measurements of the overall rates of O(1D) removal by different molecules (reaction (9a)) are very accurate and consistent

31, 32, 33

, however

distinguishing the quenching from energy transfer or reaction is often difficult. The same is applicable to reaction of O(1D) with N2 O(1D)+ N2=O+ N2

(9b).

The second channel of this reaction may lead to N2O, which is not included in the present model. It is also considered much less important at room temperature. On the contrary, the interaction between excited oxygen atom and ozone is reactive and it could produce many different products. Atkinson et al. 18 consider 2 channels O(1D)+ O3= O2+O+O

(10a)

O(1D)+ O3= O2+ O2

(10b)

equally important and responsible for about 100 % of the reaction.

Experimental data The decomposition flames of ozone were first studied by Lewis and von Elbe

34

. They

measured propagation speeds of spherical flames in a constant volume bomb from pressuretime explosion records. The initial temperature of the ozone – oxygen mixtures was close to 300 K, however, initial pressures for different mixtures were different, all below atmospheric pressure. No stretch correction was considered at that time. Due to the apparent simplicity of


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the ozone – oxygen system, these data, among others, were used to test different theories of flame propagation, e.g. 12, 35, 36.

In 1957 Streng and Grosse

37, 38

reported new burning velocity measurements, which were

most often used in comparison with modified theories, e.g.

39

and detailed modeling

40, 41

.

Streng and Grosse covered the range of ozone concentrations in oxygen from 17 to 100 % and used simple burner method with Schlieren registration. In mixtures with less than 30 % of ozone they noticed variation of the apparent burning velocity with the burner tip diameter and advised to consider these results preliminary.

Independent measurements of Pshezhetskiy et al. 42 were performed in a horizontal tube with an open end. They covered the range of ozone concentrations up to 45 % and concluded that their results are in agreement with Lewis and von Elbe 34 and Streng and Grosse 37, 38.

Finally, Mizutani et al.

43

reported detonation and deflagration properties of ozone – oxygen

mixtures up to 1.0 MPa. Experiments were performed in a closed detonation tube with a spark ignition at one end. Mizutani et al. 43 were able to observe flame propagation at 14% of ozone in the mixture, while at 20% they found a sharp increase of the flame speed. Investigation of the pressure dependence of the flame speed was performed in the mixtures from 13.4 to 14.3 % of ozone 43. No significant influence of pressure on the flame speed was found in agreement with flame propagation theories. One should note that flame propagation speeds measured cannot be easily converted into laminar burning velocities mostly due to significant heat losses 43 that affect not only flame speed but even propagation limits.


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Modeling Ozone flames were modeled using Chemkin-Pro 44. Thermal diffusion and multicomponent transport were taken into account. Adaptive mesh parameters were GRAD = 0.01 and CURV = 0.1. Typical number of grid points for grid-independent solutions was 350-450. Sensitivity analysis and reaction path analysis were performed focusing on the pure ozone flame.

Two reaction mechanisms have been used: (1) the mechanism developed in the present work and listed in Table 1; (2) the mechanism developed by Ibraguimova et al. 9 and Smekhov et al.

10

and used recently by Ombrello et al.

suggestion of Bourig et al.

11

6, 13

, and by Bourig et al.

11

. Following a

in the following it is referred to as the MSU (Moscow State

University) mechanism.

Laminar burning velocities of ozone + oxygen flames at atmospheric pressure as a function of ozone concentration in the mixture are summarized in Fig. 1. Available measurements are in general agreement with each other, yet significant scattering (especially found by Pshezhetskiy et al. 42) indicates rather large experimental uncertainties. Streng and Grosse 37, 38

covered the widest range of concentrations and approximated their results by a linear

dependence of the burning velocity on the ozone concentration. This dependence was not confirmed by the earlier theories

37

, detailed modeling

40, 41

or asymptotic analysis

45

.

Predictions of the present model and of the MSU model, also shown in Fig. 1, are essentially in very close agreement with the earlier modeling results 40, 41. One may conclude, therefore, that available laminar burning velocities of ozone are not very helpful in screening of rather old or recent kinetic schemes.


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Insignificant variation of the laminar burning velocity with pressure has been confirmed computationally. At the conditions of experiments of Mizutani et al.

43

(14 % of ozone in

oxygen) calculated burning velocity decreases from 14 cm/s at 1 atm down to 11.4 cm/s at 10 atm.

Analysis of the uncertainties in thermodynamic, transport and kinetic parameters that may affect model predictions has been performed earlier by Warnatz 40 and by Heimerl and Coffee 41

. In the present work it has been extended with the focus on newly introduced excited

species and their reactions. The enthalpies of formation of excited oxygen (438.523 kJ/mole) and of singlet O2 (94.418 kJ/mole) are reported with the accuracy corresponding to that of ground-state species

14

. Modification of the transport parameters (specifically the Lennard-

Jones potential well depth and collision diameter within 20 %) of excited oxygen or of singlet O2 does not affect calculated burning velocities. As is shown in the following, they are formed in very small quantities in ozone flames. Most sensitive reactions with respect to the burning velocity are ozone decomposition (reactions 1a and 1b) and reaction between ozone and ground-state oxygen (2). The contribution of the channel (2b) is proportional to its branching ratio.

No influence of the rate constant of reaction (3) was observed, and,

therefore, formation of singlet oxygen in reaction (3b) does not affect calculated burning velocity. Small differences between predictions of the present model and of the MSU model as the ozone concentration is increased (Fig. 1) are only due to different rate constants of reactions (1) and (2).

Ozone flame structure has not been studied experimentally, yet it is very simple and well understood since the early work of Lewis and von Elbe

35

. Detailed kinetic modeling

40, 41

showed that flame front thickness is much less than 0.1 mm at atmospheric pressure and


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initial temperature of 300 K. Previous models, however, did not include electronically excited species; therefore the modeling has been performed in the present work to analyze the fate of singlet oxygen in the flame as shown in Fig. 2. Concentration profiles of major species, O3, O2 and O predicted by the present model and the MSU model are very close. A minor difference was found in the peak value of O atom concentration: it is predicted to be 14.7% by the present mechanism and 16.9% by the MSU mechanism.

An important

qualitative dissimilarity was found in the calculated O2(a¹∆g) profiles. The MSU model shows rapid formation of singlet oxygen in the flame front up to 1.5% and then gradual consumption of it in the post-flame zone down to zero concentration. On the contrary, the present model predicts very small amount of O2(a¹∆g) formed in the flame front with gradual accumulation of it in the product zone approaching equilibrium concentrations at flame adiabatic temperature as cross-checked by Chemkin equilibrium modeling.

To elucidate the difference between singlet oxygen behavior predicted by both models, sensitivity analysis and reaction path analysis were performed in the pure ozone flame. A specific point 4 mm downstream the flame front was chosen where O2(a¹∆g) is consumed according to the MSU model and is accumulated according to the present mechanism. The calculated temperature at this point from both models is 2200 K. Reaction pathways, rate of production of singlet O2, and sensitivities for its concentration are shown in Figs. 3, 4 and 5, respectively. In these graphs excited oxygen is designated as OX and singlet O2 as O2X. The present model shows that singlet oxygen is mostly formed in reaction (3b) with smaller contribution from reactions (-5) and (8a).

The concentration of O2(a¹∆g) is positively

sensitive to the rate constants of reactions (3b) and (3a) and negatively sensitive to the rate constant of reaction (2a). Overall reaction path is governed by the gradual decrease of O


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atoms concentration and accumulation of O2 and small amount of singlet oxygen. Maximum concentration of O(1D) is below 4 ppm; it is predominantly consumed in reaction (8a).

According to the MSU model O2(a¹∆g) in the product zone is mostly consumed in reaction O2(1∆)+M=>O+O+M

(-3b)

with minor route of formation in reaction O3+M=> O2(1∆)+O+M. Note that this last reaction is not included in the present mechanism, while reaction (-3b) is considered irreversible in the MSU mechanism. Due to irreversibility of this and several other reactions in the MSU model, the predicted concentration of singlet oxygen vanishes completely which contradicts to equilibrium calculations at the adiabatic state.

Model analysis, therefore, clearly demonstrates that due to the incompleteness of the MSU mechanism (absence of many reverse reactions), it predicts an incorrect balance between O atoms, excited and ground state oxygen. This could be one of the reasons of significant overprediction of the flame propagation enhancement by O2(a¹∆g) reported by Ombrello et al. 13. Modeling proof of this hypothesis requires further development of the mechanism via inclusion of reactions between excited oxygen atoms and molecules and hydrogen-containing species, which is the objective of the author.

Conclusions

The goal of the present work was to evaluate the reliability and the accuracy of the rate constants pertinent to ozone decomposition, and to validate and analyze kinetic mechanism predictions at high temperatures. A new detailed kinetic mechanism of ozone combustion is developed. The contemporary choice of the reaction rate constants is presented with the


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emphasis on their uncertainties. Model predictions are compared with available experimental data for ozone decomposition flames and with the MSU mechanism. It is hardly possible to scrutinize either old or new models using available experimental data on ozone burning velocity.

These two models show similar performance in calculating laminar burning

velocities, yet predict largely different concentration profiles of singlet oxygen, O2(a¹∆g). More experiments with ozone flames, for instance direct measurements of singlet oxygen concentrations could be very helpful in examining ozone combustion mechanisms. Measurements of the laminar burning velocity of ozone decomposition flames at high pressures are essentially absent.

Acknowledgements Financial support of the Swedish Research Council (VR) is gratefully acknowledged.

References

(1). Nomaguchi, T.; Koda, S. Proceed. Combust. Instit. 1988, 22, 1677-1682. (2). Tachibana, T.; Hirata, K.; Nishida, H.; Osada, H. Combust. Flame 1991, 85, 515-519 (3). Magzumov, A.E.; Kirillov, I.A.; Rusanov, V.D. Combust. Explosion Shock Waves 1998, 34, 338-341 (4). Nishida, H.; Tachibana, T. J. Propuls. Power 2006, 22, 151- 157. (5). Schonborn, A.; Hellier, P.; Aliev, A.E.; Ladommatos, N. Fuel 2010, 89, 3178-3184. (6). Ombrello, T.; Won, S.H.; Ju, Y.; Williams, S. Combust. Flame 2010, 157, 1906-1915. (7). Halter, F.; Higelin, P.; Dagaut, P. Energy Fuels 2010, 25, 2909-2916 (8). Wang, Z.H.; Yang, L.; Li, B.; Li, Z.S.; Sun, Z.W.; Alden, M.; Cen, K.F.; Konnov, A.A. Combust. Flame 2012, 159, 120-129. 15 ACS Paragon Plus Environment

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(9). Ibraguimova, L.; Smekhov, G.; Shatalov, O. Recommended Rate Constants of Chemical Reactions in an H2–O2 Gas Mixture with Electronically Excited Species O2(1∆), O(1D), OH(2Σ) Involved, Institute of Mechanics of Lomonosov Moscow State University report, 2003. (10). Smekhov, G.; Ibraguimova, L.; Karkach, S.; Skrebkov, O.; Shatalov, O. High Temp. 2007, 45, 395–407. (11). Bourig, A.; Thevenin, D.; Martin, J.P.; Janiga, G.; Zahringer, K. Proc. Combust. Instit. 2009, 32, 3171-3179. (12). Hirschfelder, J.O.; Curtiss, C.F.; Campbell, D.E. J. Phys. Chem. 1953, 57, 403-414. (13). Ombrello, T.; Won, S.H.; Ju, Y.; Williams, S. Combust. Flame 2010, 157, 1916-1928. (14). Goos, E.; Burcat, A.; Ruscic, B. Ideal Gas Thermochemical Database with updates from Active Thermochemical Tables. ; June 2012. (15). Makarov, V.N.; Shatalov, O.P. Fluid Dynamics 1994, 29, 854-861. (16). Luther, K.; Oum, K.; Troe, J. Phys.Chem.Chem.Phys. 2005, 7, 2764-2770. (17). Endo, H.; Glanzer, K.; Troe, J. J. Phys. Chem. 1979, 83, 2083-2090. (18). Atkinson, R.; Baulch, D. L.; Cox, R. A.; Crowley, J. N.; Hampson, R. F.; Hynes, R. G.; Jenkin, M. E.; Rossi, M. J.; Troe, J. Atmos. Chem. Phys. 2004, 4, 1461-1738. (19). Intezarova, E.I.; Kondratiev, V.N. Izv. Akad. Nauk SSSR, Ser. Khimicheskaya 1967, 11, 2440-2446. (20). Starik, A.M.; Titova, N.S. Initiation of combustion and detonation in combustible mixtures by excitation of molecular oxygen into the O2(a¹∆g)-state. Khim. Fiz. 2001, 20, 1725 (in Russian).


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(21). Vasiljeva, A.N.; Klopovskiy, K.S.; Kovalev, A.S.; Lopaev, D.V.; Mankelevich, Y.A.; Popov, N.A.; Rakhimov, A.T.; Rakhimova, T.V. J. Phys. D: Appl. Phys. 2004, 37, 24552468. (22). Steinfeld, J.I.; Adler-Golden, S.M.; Gallagher, J.W. J. Phys. Chem. Ref. Data 1987, 16, 911-951. (23). Gauthier, M.; Snelling, D.R. J. Chem.Phys. 1971, 54, 4317-4325. (24). Konnov, A.A. Combust. Flame 2008, 152, 507-528. (25). Baulch, D.L.; Drysdale, D.D.; Duxbury, J.; Grant, S.L. Evaluated kinetic data for high temperature reactions. Vol. 3. Homogeneous gas phase reactions of O2 - O3 systems, the CO - O2 - H2 system and of sulfur-containing species. London, 1976, Butterworths. (26). Warnatz, J. Rate coefficients in the C/H/O system Combustion Chemistry. in Combustion Chemistry (W.C. Gardiner, Jr., Ed.) Springer-Verlag, New York, 1984, p. 197. (27). Cupitt, L.T.; Takacs, G.A.; Glass, G.P. Int. J.Chem.Kinet. 1982, 14, 487-497. (28). Braginskiy, O.V.; Vasilieva, A.N.; Klopovskiy, K.S.; Kovalev, A.S.; Lopaev, D.V.; Proshina, O.V.; Rakhimova, T.V.; Rakhimov, A.T. J. Phys. D: Appl. Phys. 2005, 38, 36093625. (29). Azyazov, V.N.; Mikheyev, P.; Postell, D.; Heaven, M.C. Chem. Phys. Lett. 2009, 482, 56-61. (30). Doroshenko, V.M.; Kudryavtsev, N.N.; Smetanin, V.V. High Energy Chem. 1992, 26, 227-230. (31). Dunlea, E.J.; Ravishankara, A.R. Phys.Chem.Chem.Phys. 2004, 6, 2152-2161. (32). Blitz, M.A.; Dillon, T.J.; Heard, D.E.; Pilling, M.J.; Trought, I.D. Phys.Chem.Chem.Phys. 2004, 6, 2162-2171. (33). Strekowski, R.S.; Nicovich, J.M.; Wine, P.H. Phys.Chem.Chem.Phys. 2004, 6, 21452151.


Energy & Fuels

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(34). Lewis, B.; von Elbe, G. J. Chem. Phys. 1934, 2, 283-290. (35). Lewis, B.; von Elbe, G. Chem. Revs. 1937, 21, 347-358. (36). Sandri, R. Can. J. Chem. 1956, 34, 324-330. (37). Streng, A.G.; Grosse, A.V. J. Am. Chem. Soc. 1957, 79, 1517-1518. (38). Streng, A.G.; Grosse, A.V. Proc. Combust. Instit. 1957, 6, 264-273. (39). Sandri, R. Can. J. Chem. 1957, 35, 474-476. (40). Warnatz, J. Ber. Bunsenges. Phys. Chem. 1978, 82, 193-200. (41). Heimerl, J.M.; Coffee, T.P. Combust. Flame 1980, 39, 301-315. (42). Pshezhetskiy, S.Ya.; Kamenetskaya, S.A.; Gribova, Ye.I.; Pankratov, A.V.; Morozov, N.M.; Pospelova, I.N.; Apin, A.Ya.; Siryatskaya, V.N.; Slavinskaya, N.A.; Cherednichenko, V.M. Probl. Fizich. Khimii 1959, 2, 27-38. (43). Mizutani, T.; Matsui, H.; Sanui, H.; Yonekura, M. J. Loss Prev. Proc. Industr. 2001, 14, 559-565. (44). Reaction Design, CHEMKIN-PRO 15101:San Diego, 2010 (45). Rogg, B.; Linan, A.; Williams, F.A. Combust. Flame 1986, 65, 79-101. (46). Konnov, A.A. Khimicheskaya Fizika 2004, 23, 5-18. (47). Krivonosova, O.E.; Losev, S.A.; Nalivaiko, V.P.; Mukoseev, Yu.K.; Shatalov, O.P. Recommended Data on the Rate Constants of the Chemical Reactions between Molecules Consisting of N and O Atoms. In: Plasma Chemistry, vol. 14, (Smirnov BM, Ed.), Energoatomizdat, Moscow, 1987, pp. 3-31 (In Russian).


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Page 19 of 25

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Energy & Fuels

Table 1. Ozone kinetic mechanism, units are cm3 - mole - s - cal - K, k = ATn exp(-Ea/RT). UF - uncertainty factor.

No 1a

1b

Reaction

A

n

Ea

T range, K

4.29E+17

-1.5

0 80-1500

5.10E+21

-3.2

0

6.53E+17

-1.5

0 100-1000

UF

Source

1.2

16 b,c

1.2

16 a,b,c

Ar = 0, O2 = 0.95,

1.1

17

O3 = 2.5, O = 4

2

15

O2+O+Ar= O3+Ar

O2+O+M= O3+M

Enhanced third-body efficiencies (relative to N2):

1.33E+22

-3.3

0

16

Enhanced third-body efficiencies (relative to N2): Ar = 0, O2 = 1.07,

1.1

18

O3 = 2.5, O = 4

2

15

2a

O3+O= O2+ O2

4.82E+12

0

4094 200-400

1.15

18 c

2b

O3+O= O2(1∆)+ O2

1.44E+11

0

4094

3

21 d

3a

O+O+M=O2+M

1.00E+17

-1.0

2

26 a,c

O = 28.8, O2 = 8, N2 = 2,

2

46, 47 c

O3 = 8

2

25 c

5

See text

1.5

18 a,c

0 300 - 5000

Enhanced third-body efficiencies (relative to Ar):

3b

O+O+M= O2(1∆)+M

1.00E+16

-1.0

0

Enhanced third-body efficiencies (relative to Ar): O = 28.8, O2 = 8, N2 = 2, O3 = 8 4a

O2(1∆)+M= O2+M

1.80E+06

0

397 100-450

Enhanced third-body efficiencies (relative to O2): 19 ACS Paragon Plus Environment

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Page 20 of 25

O = 0, Ar = 0.06, N2 = 0.1

2

See text

4b

O2(1∆)+O= O2+O

4.20E+08

0

0

3

27 d

5

O2(1∆)+O+M=O+ O2+M

3.60E+15

0

0 300

10

28 a,d

Enhanced third-body efficiencies (relative to O2): Ar = 0.63

21

6

O2(1∆)+ O3= O2+ O2+O

3.13E+13

0

5644 280-360

1.2

18 c

7

O(1D)+ O2(1∆)=O+ O2

6.03E+12

0

0 300

10

30 d

8a

O(1D)+ O2=O+ O2(1∆)

1.59E+13

0

-139 200-350

1.2

18 c

8b

O(1D)+ O2=O+ O2

2.81E+12

0

-139

5

See text

9a

O(1D)+M=O+M

4.80E+11

0

1.2

32 a,e,c

2

21 d

0 300

Enhanced third-body efficiencies (relative to Ar): O2 = 0, N2 = 0, O = 10 9b

O(1D)+ N2=O+ N2

1.26E+13

0

-230 210-370

1.2

31 e,c

10a

O(1D)+ O3= O2+O+O

7.23E+13

0

0 100-400

1.1

18 c

10b

O(1D)+ O3= O2+ O2

7.23E+13

0

0 100-400

1.1

18 c

a All other species have efficiencies equal to unity. b Rate constant is the sum of two expressions. c Review d Estimate e Measurements f Theoretical calculations


Page 21 of 25

0

Burning velocity, cm/s

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Energy & Fuels

500

20

40

60

80

100 500

400

400

300

300

200

200

100

100

0 0

20

40

60

0 100

80

Ozone %

Fig. 1. Laminar burning velocity of ozone + oxygen flames at atmospheric pressure. Symbols – experiments. Triangles: Lewis and von Elbe diamonds: Streng and Grosse

34

, circles: Pshezhetskiy et al.

37, 38

42

,

. Lines: modeling. Solid line: present mechanism, dashed

line: MSU mechanism.


Energy & Fuels

1.0

0.0

0.2

0.4

0.6

O3

0.8

1.0 0.04

O2 0.03

0.8

0.6 0.02

0.4

Mole fraction O2(1∆)

-0.2

Mole fraction O3, O2, O

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 22 of 25

0.01 0.2

0.0 -0.2

O

0.0

0.2

0.4

0.6

0.8

0.00 1.0

Distance, cm

Fig. 2. Flame structure of pure ozone flame at atmospheric pressure. Solid lines: O3, O2 and O. Dash-dot line: O2(a¹∆g) predicted by the present model and dashed line – by the MSU model.


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Energy & Fuels

Fig. 3. Reaction path analysis in pure ozone flame 4 mm downstream the flame front. Left: present model, right: MSU model.


Energy & Fuels

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Fig. 4. Rate of production of singlet O2 in pure ozone flame 4 mm downstream the flame front. Left: present model, right: MSU model.


Page 24 of 25

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Energy & Fuels

Fig. 5. Sensitivity analysis for singlet O2 in pure ozone flame 4 mm downstream the flame front. Left: present model, right: MSU model.


Modeling Ozone Decomposition Flames - Energy & Fuels (ACS

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