Effect of Ethanol on Ethylene Consumption in Premixed Laminar

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Effect of Ethanol on Ethylene Consumption in Premixed Laminar Flames of Ethylene and Ethanol: a Modeling Study Boyang Su, Jinou Song, Chaoxu Chen, Zhongrui Zhao, and Zhijun Li Energy Fuels, Just Accepted Manuscript • DOI: 10.1021/acs.energyfuels.6b02606 • Publication Date (Web): 28 Mar 2017 Downloaded from http://pubs.acs.org on March 30, 2017

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Energy & Fuels

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Effect of Ethanol on Ethylene Consumption in Premixed Laminar

2

Flames of Ethylene and Ethanol: a Modeling Study

3

Boyang Su, Jinou Song, Chaoxu Chen, Zhongrui Zhao, Zhijun Li

4

State Key Laboratory of Engines, Tianjin University, Tianjin, 300072, China

5 6 7

ABSTRACT: The effect of ethanol on the ethylene consumption in fuel-rich, premixed,

8

laminar, burner-stabilized flames at atmospheric pressure was investigated. A pure ethylene

9

flame and three ethylene/ethanol flames with different ethanol fractions were simulated at the

10

same equivalence ratio. The results showed that the different reaction rates for ethylene

11

consumption in the flames were related to the reaction kinetics in these flames with an

12

insignificant thermal effect. Changes in key radical concentrations in the flames were

13

observed depending on initial ethanol mole fraction in the fuel, and the reaction pathways

14

responsible for the production and destruction of ethylene were identified. The chemical

15

behaviors differed significantly at different flame heights above the burner. At the flame

16

height with a temperature of 769 K, a decrease in OH concentration was responsible for the

17

reduction in the reaction rate for ethylene consumption with the addition of ethanol. At the

18

flame height with a temperature of 1470 K, the normalized ethylene concentration in the

19

flames increased with the increase of the initial ethanol fraction in the fuel, the reason for

20

which appeared to be the decomposition reactions into ethylene rather than the changes of

21

species pool in the flames.

22 1

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1. INTRODUCTION

2

The oxygenates are not only the important alternatives to fossil fuels for transportation

3

purposes 1, but also used as additives to gasoline or diesel fuel to minimize soot, carbon

4

monoxide and unburned hydrocarbon emissions from engines 2-6. Many experimental,

5

theoretical and computer modeling studies have been devoted to address sooting reduction in

6

engines and flames by oxygenated additives and explain the behavior in fundamental terms

7

7-14

8

hydrocarbons in the combustion of their blends.

. However, less attention has been given to the interaction of oxygenates with

9

Tran et al 15 investigated the premixed laminar flames of ethanol and methane stabilized

10

on a burner at a pressure of 6.7 kPa. The equivalence ratio was kept the same at φ = 1 for the

11

pure methane flame and the methane/ethanol flame. In the methane/ethanol flame, about 30%

12

of methane was replaced with ethanol, and the temperature profile was very similar to that for

13

the pure methane flame. However, there were obvious differences in mole fraction profiles of

14

methane versus the height above the burner (HAB). The slope of the mole fraction profile of

15

methane was about - 0.0249 for the pure methane flame, and about - 0.0184 for the

16

methane/ethanol flame, indicating that the reaction rate for methane consumption in the

17

methane/ethanol flame was lower than that in the pure methane flame.

18

Gerasimov 16 studied the structure of atmospheric-pressure fuel-rich premixed ethylene

19

flames with and without ethanol using molecular beam mass spectrometry. The two flames

20

were measured with the same equivalence ratio (φ = 1.7). Although the flame temperature

21

profiles and the initial normalized mole fraction of ethylene were almost the same for the two

22

flames, the normalized mole fractions of ethylene for the ethylene/ethanol flames became 2


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larger than that for pure ethylene flame with the increase of HAB, indicating a lower reaction

2

rate for ethylene consumption in the ethylene/ethanol flame. Similar observation was

3

obtained in Korobeinichev’s work 17.

4

Dmitriev et al 18 investigated the effect of adding methyl pentanoate (MP) on the species

5

pool in a rich premixed flame fueled by n-heptane/toluene blend (7/3 by volume of liquids) at

6

atmospheric pressure. The measured and predicted mole fraction profiles of reactants and

7

major stable products showed a significant slowdown in the reaction rates for both n-heptane

8

and toluene consumption with the addition of MP. The effects of methyl tert-butyl ether

9

(MTBE) and ethanol on the oxidation of n-heptane were also observed in our earlier works

10

19-20

11

of their blends, and it should be studied further.

12

. Thus there may exist the interaction of oxygenates with hydrocarbons in the combustion

The combustion research community has endeavored to identify the effect of oxygenated

13

additive on benzene and soot formation in hydrocarbon flames 21-24. The present work used

14

detailed chemical kinetic modeling to address the effects of ethanol on the ethylene

15

consumption in premixed laminar flames of ethylene and ethanol and to explain the behavior

16

in fundamental terms with the help of the available test data 16 and chemical mechanisms 25-27.

17 18

2. METHODOLOGY

19

Numerical modeling was performed with the PREMIX code from the CHEMKIN Ⅱ

20

using an experimental temperature profile as an input. Thermal diffusion has been included.

21

Convergence criteria were decreased until a grid independent solution was found. The

22

chemical mechanism used in this study is a mechanism modified by Gerasimov et al 16, which 3


28

by

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1

consists of the hydrocarbon oxidation mechanism developed by Frenklach and co-workers

2

25-26

3

together with thermochemistry and transport data files in Chemkin format can be found in

4

Supplementary material (mmc1.zip and mmc4.doc) in literature 16. Three mechanisms have

5

been employed in the work of Gerasimov et al. The simulation results for these three

6

mechanisms show similar trends, although there are obvious variations between the predicted

7

values. It is noticed that the simulation of mechanism 1 well reproduces the mole fraction

8

profiles of reactants than mechanism 2 or 3. Therefore, the mechanism 1 was selected

9

because only reactant C2H4 is concerned in this work.

10

and the ethanol oxidation mechanism taken from Marinov 27. This kinetic mechanism

Four flames stabilized on a Botha–Spalding flat burner at atmospheric pressure were

11

calculated with different ratios of ethylene to ethanol (Table 1), while other flame conditions

12

were kept as the same as described in the literature 16, i.e. all four flames with the same

13

equivalence ratio of 1.7, flowrate of 25.8 cm3/s, initial temperature of the cold mixtures at

14

293 K and temperature profile of the flames.

15

Flames 1 and 4 have been measured by Gerasimov et al 16 using the MBMS setup. The

16

mole fraction uncertainty for the flame reactants and major products (C2H4, C2H5OH, O2, CO,

17

CO2 and H2O) was estimated to be ±15% of the maximum mole fraction values. For other

18

species, mole fractions were determined to within a factor of about 2. At HAB = 0.3 mm, the

19

measured mole fraction of C2H4 is 0.0622908 for Flame 1 and 0.0325028 for Flame 4. At

20

HAB = 0.8 mm, the measured mole fraction of C2H4 is 0.01581888 for Flame 1 and

21

0.01090452 for Flame 4. It is obvious that the discrepancy of C2H4 mole fraction at a fixed

22

HAB between Flames 1 and 4 is not be caused by the measurement uncertainty. The 4


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measured data indicated that the widths of the flame zone and the temperature distributions

2

remained much the same for the two flames, and the discrepancy was less than the

3

uncertainty of the measurements, so the experimental temperature profile of Flame 1 was

4

used as an input in the calculation of all four flames and the temperature effect neglected.

5

The basic objective of the analysis was to determine the major reactions leading to the

6

destruction of C2H4 and to determine how the relative importance of those reactions changed

7

as a result of the addition of ethanol. The approach used in this paper took advantage of the

8

postprocessor utility available in CHEMKIN that allows calculation of the rates of

9

destruction (ROD) and the rates of production (ROP) of a given species in the mechanism by

10

each reaction involving this species. The ROD or ROP represents the fractional contribution

11

of a destruction or production reaction for a species, which is calculated through being

12

divided by the total amount of this species consumed or produced. To capture the kinetics as

13

much as possible, all reactions contributing to the production or destruction of more than 0.01%

14

of the total flux of this species were included in the analysis.

15 16

3. RESULTS AND DISCUSSION

17

3.1. Overview

18

Figure 1 shows the simulated mole fraction profiles of reactants (C2H4, O2 and C2H5OH)

19

and major products (CO, CO2, H2, H2O) against earlier experimental data obtained by

20

Gerasimov et al 16 for Flame 4. The simulation in this work similar to that in literature 16 well

21

reproduces the mole fraction profiles of reactants, as well as H2 and CO2 in these flames.

22

Some disagreement for water and carbon monoxide is within the measurement error. 5


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Figure 2 shows the temperature profile of the Flame 1, the normalized mole fraction

2

profiles of C2H4 in Flames 1 and 4 measured by Gerasimov 16, and the normalized mole

3

fraction profiles of C2H4 in four flames calculated in this work. The normalized mole fraction

4

of C2H4 in a flame is defined as the ratio of local mole fraction of C2H4 in the flame to the

5

initial mole fraction of C2H4 in the fuel. For the Flames 1 and 4, the measured and simulated

6

mole fraction profiles of C2H4 agree very well, and the widths of flame zone remain much the

7

same, consistent with the temperature profile. This further validates the methodology used in

8

this work. As seen from Figure 2, with the increase of initial mole fraction of ethanol in the

9

fuel, the normalized mole fraction of C2H4 becomes larger at a fixed height of flame (For

10

example, the increment from Flames 1 to 4 are 0.03085 at HAB = 0.3 mm and 0.06807 at

11

HAB = 0.8 mm). In other words, the addition of ethanol slows down the C2H4 consumption

12

due to the chemical kinetics in these flames.

13

The uncertainty in temperature measurement also affects the modeling results 29-30. As

14

seen from Figure 3, at a fixed HAB, the normalized mole fraction of C2H4 for Flame 1

15

increases with the decrease of the flame temperature. If the temperature of Flame 1 decreased

16

about 50 K, the normalized mole fraction of C2H4 for Flame 1 would increase to the same as

17

that for Flame 4 at HAB = 0.3 mm. If the temperature of Flame 1 decreased about 82 K, the

18

normalized mole fraction of C2H4 for Flame 1 would increase to the same as that for Flame 4

19

at HAB = 0.8 mm. The temperature profiles for Flames 1 and 4 were measured by a

20

Pt/Pt+10%Rh thermocouple with an accuracy of ±25 K 16. The discrepancy in the flame

21

temperature caused by the uncertainty in temperature measurement is obviously less than 50

22

K, so variations of normalized mole fraction from Flame 1 to 4 cannot be attributed to the 6


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uncertainty of flame temperature or thermal effect, considering that the measured temperature

2

profile of Flame 4 is slightly higher than that of Flame 1 16.

3

To ascertain the reasons for the variations of the normalized mole fraction of C2H4 under the

4

given conditions, the pathways of C2H4 consumption will be analyzed at HAB = 0.3 mm with

5

the flame temperature of 769 K (representing the low temperature region of the flames) and

6

at HAB = 0.8 mm with the temperature of 1406 K (representing the high temperature region

7

of the flames).

8

3.2. Analysis at HAB = 0.3 mm (769 K)

9

Figure 4 presents the major pathways for production (positive value) and destruction

10

(negative value) of C2H4 and ethanol at HAB = 0.3 mm (769 K). The reaction pathways show

11

that the destruction of C2H4 and C2H5OH are dominated by the reactions with OH, H and O.

12

The major reactions for C2H4 destruction and production are reactions (1) – (5) (Figure 4 (a)):

13

C2H4 + H (+ M) = C2H5 (+ M)

(1)

14

C2H4 + OH = C2H3 + H2O

(2)

15

C2H4 + OH = C2H4OH

(3)

16

C2H4 + O = CH3 + HCO

(4)

17

C2H5 + O2 = C2H4 + HO2

(5)

18

The reactions (1) – (3) account for about 90% of C2H4 consumption in Flames 1 – 3, and

19

the reactions (1) – (2) account for about 92% of C2H4 consumption in Flame 4. Therefore, the

20

C2H4 consumption via the reactions with O and CH3 is less important. It is also shown in

21

Figure 4 (a) that the fractional contribution of reaction (1) increases with the increase of

22

initial ethanol fraction in the fuel, while that of reactions (2) and (3) decreases. 7


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1

Figure 4 (b) shows that more C2H4OH is produced with the increase of initial ethanol

2

fraction in the fuel. Thus decomposition of C2H4OH into C2H4 and OH 8 will be enhanced

3

with the increase of initial ethanol fraction, counteracting the C2H4 consumption through

4

reactions (3). The fractional contribution of the reactions (1) – (3) to the C2H4 consumption is

5

related to mole fractions of H and OH. Figure 5 shows the mole fraction profiles of H and

6

OH in the vicinity of HAB = 0.3 mm. The H mole fraction profiles are very similar for all

7

four flames, while the OH mole fraction decreases significantly with the increase of initial

8

ethanol fraction in the fuel. The reduction of OH mole fraction slows down the C2H4

9

consumption through reactions (2) and (3), leading to a relative increase in fractional

10

contribution of reaction (1) with the increase of initial ethanol fraction (Figure 4 (a)). In fact,

11

the effect of reaction (1) on C2H4 consumption varies slightly because the H profiles are

12

much the same for the four flames. Therefore, at HAB = 0.3 mm, the addition of ethanol

13

slows down the C2H4 consumption by decreasing OH mole fraction in flames, leading to an

14

increase in the normalized mole fraction of C2H4 (Figure 2).

15

In Figure 6, rF is the ratio of the local mole fraction of C2H4 in an ethylene/ethanol

16

flame (i.e. Flames 2, 3 or 4) to that in the pure ethylene flame (i.e. Flame 1); rS is the ratio of

17

total reaction rate for C2H4 consumption in an ethylene/ethanol flame to that in the pure

18

ethylene flame. r2, r3 and r4 are defined as the ratio of reaction rate for C2H4 consumption in

19

an ethylene/ethanol flame to that in the pure ethylene flame via reactions (2), (3) and (4),

20

respectively. As shown in Figure 6, with the increase of initial ethanol fraction in the fuel, the

21

rF decreases, and the rS decreases even more, indicating that C2H4 consumption slows down

22

with the addition of ethanol. This explains why the normalized mole fraction of C2H4 8


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becomes larger at HAB = 0.3 mm with the increase of initial mole fraction of ethanol in the

2

fuel (Figure 2).

3

It also can be observed from Figure 6 that reaction (3) is the dominant factor to cause the

4

rS slowdown. To understand how adding ethanol to the fuel affects the concentration of OH,

5

the main chemical reactions involving OH in four flames are identified and listed in Figure 7.

6

The consumption reactions for OH in the Flames 2, 3, 4 differ from that in the Flame 1. With

7

the addition of ethanol, OH destructs mainly via three new pathways:

8

C2H5OH + OH = C2H4OH + H2O

(6)

9

C2H5OH + OH = CH3CHOH + H2O

(7)

10

C2H5OH + OH = CH3CH2O + H2O

(8)

11

OH consumption through the three new pathways increases with the increase of the

12

initial mole fraction of ethanol in the fuel. In Flame 4, these new reaction pathways account

13

for 67% of OH consumption. These were supported by the results of McNesby et al [22] who

14

reported a 32% of ethanol consumption via the reactions with O and a 63% of ethanol

15

consumption via the reactions with OH in the lean premixed flame region. These competing

16

reactions initiated by ethanol suppressed the reactions of C2H4 with O and OH, and slowed

17

down the C2H4 consumption in the ethylene/ethanol flames.

18

Overall, at HAB = 0.3 mm, the calculation predicts that the addition of ethanol to the

19

fuel slows down the C2H4 consumption by decreasing the amount of OH available for the

20

reactions consuming C2H4, leading to an increase in the normalized mole fraction of C2H4

21

with the increase of the initial ethanol fraction in the fuel.

22

3.3. Analysis at HAB = 0.8 mm (1406 K) 9


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1

Figure 8 presents the major pathways for C2H4 consumption at HAB = 0.8 mm. The C2H4

2

consumption is still dominated by the reactions with OH, H and O, but the reaction pathways

3

at HAB = 0.8 mm differ significantly from that at HAB = 0.3 mm. The dominated pathway of

4

the reaction of C2H4 with H is reaction (9) instead of reaction (1), and accounts for about 50%

5

of C2H4 consumption, which is consistent with the simulated results in a constant-pressure

6

(up to 0.1 MPa) reactor model with a equivalence ratio of 2.0 and a final temperature of 2177

7

K [8]. But McNesby et al [22] reported a 91% of C2H4 consumption via the reaction pathway

8

(9) in a neat opposed flow ethylene/air flame at a temperature of 1700 K. The C2H4

9

consumption via the reactions with O cannot be neglected anymore. At HAB = 0.8 mm, C2H4

10

reacts with O through two major pathways: reactions (4) and (10). Together these two

11

pathways account for 30% of C2H4 consumption. For the reactions of C2H4 with OH, only the

12

pathway (2) is important, and its fractional contribution increases with the increase of the

13

initial ethanol mole fraction in the fuel, while the reverse happens at HAB = 0.3 mm.

14

C2H4 + H = C2H3 + H2

(9)

15

C2H4 + O = CH2HCO+H

16

Figure 9 shows the mole fraction profiles of H, OH and O in the vicinity of HAB = 0.8

(10)

17

mm. H mole fraction profiles are very similar, while OH mole fraction increases and O mole

18

fraction decreases significantly with the increase of the initial fraction of ethanol in the fuel,

19

leading to an increased fractional contribution of reaction (2) and a decreased fractional

20

contribution of reactions (4) and (10) (see Figure 8).

21 22

Figure 10 presents the normalized C2H4 mole fractions and the reaction rates for C2H4 consumption at HAB = 0.8 mm. In this figure, r4+10 is the sum of reactions (4) and (10). For 10


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the explanation of other symbols see Figure 6. As shown in Figure 10, with the increase of

2

the initial ethanol fraction in the fuel, both rF and rS decrease in a similar trend, indicating

3

that the consumption of C2H4 is more dependent on the mole fraction of C2H4 than the mole

4

fraction of ethanol. This can be understood by comparison of r2 with r4+10. With the

5

addition of ethanol, the consumption of C2H4 decreases through reactions with O and

6

increases through reactions with OH, the outcome of which is little influence of ethanol on

7

the total reaction rate for C2H4 consumption.

8

The main chemical reactions involving ethanol in four flames are identified and listed in

9

Figure 11, which differ significantly from those at HAB = 0.3 mm (Figure4 (b)). At HAB =

10

0.8 mm with high flame temperature, ethanol decomposition occurs and the decomposition

11

reaction to ethylene and water (i.e. reaction (11)) accounts for approximately 12.6% of the

12

ethanol consumption.

13

CH3CH2OH + M = C2H4 + H2O + M

(11)

14

McNesby et al [22] reported a 58% of ethanol consumption via the reaction pathway (11)

15

at approximately 1500 K in the absence of oxygen. But Song et al [8] reported a 5% of

16

ethanol consumption via the reaction pathway (11) and 18% of ethanol consumption via the

17

reaction pathway (12 - 13) in a constant-pressure reaction model.

18

CH3CH2OH + X = CH2CH2OH + XH

(12)

19

CH2CH2OH + M = C2H4 + OH + M

(13)

20

In this work, the consumption of ethanol via reaction pathway (12 - 13) is about 8%.

21

These decomposition reactions into C2H4 will cause an increase in the mole fraction of C2H4

22

at HAB = 0.8 mm with the increase of initial mole fraction of ethanol in the fuel (Figure 2). 11


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1

Overall, at HAB = 0.8 mm, the calculation predicts that the addition of ethanol has no

2

obvious effect on the reaction rate for C2H4 consumption. The decomposition reactions into

3

C2H4 increase the mole fraction of C2H4 in the flames, leading to an increase in the

4

normalized mole fraction of C2H4 with the increase of the initial ethanol fraction in the fuel.

5 6

4. CONCLUSIONS

7

The effect of ethanol on the C2H4 consumption in fuel-rich, premixed, burner-stabilized

8

flames at atmospheric pressure was investigated. A pure C2H4 flame and three

9

ethylene/ethanol flames with different ethanol fractions were simulated at the same

10

equivalence ratio. Because the temperature distributions in these flames are nearly the same,

11

the different reaction rates for C2H4 consumption in the flames are attributed to the chemical

12

kinetics in these flames. Analysis of the reaction pathways in the mechanisms was performed

13

in order to identify the reactions responsible for the production and destruction of C2H4.

14

Changes in key radical concentrations in the flames have been observed depending on initial

15

ethanol mole fraction in the fuel and the chemical behaviors differ significantly at different

16

flame heights above the burner.

17

At HAB = 0.3 mm with the flame temperature of 769 K, the ethanol consumption is

18

dominated by the reactions with OH and H. An increasing initial ethanol mole fraction in the

19

fuel, which has little influence on H concentration, causes a decrease in OH concentration,

20

leading to an increase in the normalized mole fraction of C2H4 in the flame.

21 22

At HAB = 0.8 mm with the temperature of 1470 K, the C2H4 consumption is dominated by the reactions with OH, H and O, and the reaction pathways differ significantly from that at 12


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HAB = 0.3 mm. The concentrations of OH, H and O vary with the addition of ethanol, but the

2

total reaction rate for C2H4 consumption happens to be similar for the four flames. At HAB =

3

0.8 mm with a high flame temperature, the decomposition reactions into ethylene are

4

responsible for an increase in the normalized mole fraction of C2H4 with the increase of the

5

initial ethanol fraction in the fuel.

6

In summary, it has been established that the addition of ethanol to the ethylene premixed

7

flame influences the reaction rate for ethylene consumption through effects on the some key

8

radical concentrations, which changes the relative importance of some key radical reactions,

9

although the total reaction rate for ethylene consumption happens to be similar at HAB = 0.8

10

mm for the four flames. Besides, the pathways of C2H4 consumption differ significantly

11

under different flame temperatures.

12 13

AUTHOR INFORMATION

14

Corresponding Author

15

*Phone: +86(0)22 27406842. Fax: +86(0)22 27383362.

16

E-mail: [email protected]

17 18 19 20

ACKNOWLEDGEMENTS Funding support for this work was provided by the National Natural Science Foundation of China (Grant No. 51576139).

21 22 13


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(1) Sadeghinezhad, E.; Kazi, S. N.; Sadeghinejad, F.; Badarudin, A.; Mehrali, M.; Sadri, R.;

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Safaei, M. R. Renewable Sustainable Energy Rev. 2014, 30, 29-44.

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(2) Mueller, C. J.; Martin, G. C. SAE Technical Paper, Paper No. 2002-01-1631, 2002,

5

(3) Huang, Z. H.; Lu, H. B.; Jiang, D. M.; Zeng, K.; Liu, B.; Zhang, J. Q.; Wang, X. B.

6 7 8 9 10

Energy Fuels 2005, 19, 403-410. (4) Liao, S. Y.; Jiang, D. M.; Cheng, Q.; Huang, Z. H.; Zeng, K. Energy Fuels 2006, 20, 84-90. (5) Thewes, M.; Muether, M.; Pischinger, S.; Budde, M.; Brunn, A.; Sehr, A.; Adomeit, P.; Kankermayer, J. Energy Fuels 2011, 25, 5549-5561.

11

(6) Yang, W. R.; Sen, A. Chemsuschem 2010, 3, 597-603.

12

(7) Westbrook, C. K.; Pitz, W. J.; Curran, H. J. J. Phys. Chem. A 2006, 110, 6912-6922.

13

(8) Song, K. H.; Nag, P.; Litzinger, T. A.; Haworth, D. C. Combust. Flame 2003, 135,

14

341-349.

15

(9) Lapuerta, M.; Armas, O.; Ballesteros, R.; Fernandez, J. Fuel 2005, 84, 773-780.

16

(10) Lin, Y. C.; Lee, W. J.; Wu, T. S.; Wang, C. T. Fuel 2006, 85, 2516-2523.

17

(11) Cheung, C. S.; Zhu, L.; Huang, Z. Atmos. Environ. 2009, 43, 4865-4872.

18

(12) Kousoulidou, M.; Fontaras, G.; Ntziachristos, L.; Samaras, Z. Fuel 2010, 89, 3442-3449.

19

(13) Dagaut, P.; Togbe, C. Fuel 2010, 89, 280-286.

20

(14) Qi, F. Proc. Combust. Inst. 2013, 34, 33-63.

21

(15) Tran, L. S.; Glaude, P. A.; Fournet, R.; Battin-Leclerc, F. Energy Fuels 2013, 27,

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2226-2245. 14


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1 2 3 4 5 6

Energy & Fuels

(16) Gerasimov, I. E.; Knyazkov, D. A.; Yakimov, S. A.; Bolshova, T. A.; Shmakov, A. G.; Korobeinichev, O. P. Combust. Flame 2012, 159, 1840-1850. (17) Korobeinichev, O. P.; Yakimov, S. A.; Knyazkov, D. A.; Bolshova, T. A.; Shmakov, A. G.; Yang, J. Z.; Qi, F. Proc. Combust. Inst. 2011, 33, 569-576. (18) Dmitriev, A. M.; Knyazkov, D. A.; Bolshova, T. A.; Shmakov, A. G.; Korobeinichev, O. P. Combust. Flame 2015, 162, 1964-1975.

7

(19) Song, J. O.; Yao, C. D.; Liu, S. Y.; Xu, H. J. Energy Fuels 2008, 22, 3806-3809.

8

(20) Song, J. O.; Yao, C. D.; Liu, S. Y.; Tian, Z. Y.; Wang, J. Fuel 2009, 88, 2297-2302.

9

(21) Wu, J. T.; Song, K. H.; Litzinger, T.; Lee, S. Y.; Santoro, R.; Linevsky, M.; Colket, M.;

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Liscinsky, D. Combust. Flame 2006, 144, 675-687. (22) McNesby, K. L.; Miziolek, A. W.; Nguyen, T.; Delucia, F. C.; Skaggs, R. R.; Litzinger, T. A. Combust. Flame 2005, 142, 413-427.

13

(23) McEnally, C. S.; Pfefferle, L. D. Proc. Combust. Inst. 2007, 31, 603-610.

14

(24) Bennett, B. A. V.; McEnally, C. S.; Pfefferle, L. D.; Smooke, M. D.; Colket, M. B.

15

Combust. Flame 2009, 156, 1289-1302.

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(25) Appel, J.; Bockhorn, H.; Frenklach, M. Combust. Flame 2000, 121, 122-136.

17

(26) Wang, H.; Frenklach, M. Combust. Flame 1997, 110, 173-221.

18

(27) Marinov, N. M. Int. J. Chem. Kinet. 1999, 31, 183-220.

19

(28) Kee, R. J.; Rupley, F. M.; Miller, J. A. Sandia Laboratories Report S 89-8009B, 1993.

20

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21

F. Combust. Flame 2012, 159, 2324-2335.

15


Energy & Fuels

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

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(30) Dooley, S.; Dryer, F. L.; Yang, B.; Wang, J.; Cool, T. A.; Kasper, T.; Hansen, N. Combust. Flame 2011, 158, 732-741.

3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 16


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Page 17 of 24

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

Energy & Fuels

1

Legends

2

Figure 1. Mole fraction profiles of reactants and major products in Flame 4 (Symbols:

3

experiment, black solid lines: modeling in present work, red dashed lines: modeling in

4

literatures 16).

5

Figure 2. Measured temperature profile for Flame 1, and calculated (for 4 flames) and

6

measured (for Flames 1 and 4) normalized mole fraction profiles of ethylene.

7

Figure 3. Normalized mole fraction profiles of ethylene for Flame 4 and 1 at different flame

8

temperatures.

9

Figure 4. ROP and ROD analyses of C2H4 and ethanol at HAB = 0.3 mm.

10

Figure 5. Calculated H and OH profiles in the vicinity of HAB = 0.3 mm.

11

Figure 6. Normalized mole fractions and consumption reaction rates of C2H4 at HAB = 0.3

12

mm.

13

Figure 7. ROP and ROD analyses of OH at HAB = 0.3 mm.

14

Figure 8. ROD analyses of C2H4 at HAB = 0.8 mm.

15

Figure 9. Calculated H, OH and O profiles in the vicinity of HAB = 0.8 mm.

16

Figure 10. Normalized Mole fractions and consumption reaction rates of C2H4 at HAB =

17

0.8mm.

18

Figure 11. ROD analyses of ethanol at HAB = 0.8 mm.

19 20 21 22 17


Energy & Fuels

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

1 2

Page 18 of 24

Tables Table 1 Inlet conditions of cold mixtures mole fraction in mixture

ethanol fraction

Case O2

C2H5OH

Flame1

0.0880

0.0000

0.0

Flame 2

0.0792

0.0088

0.1 0.1550

Ar

in the fuel

C2H4

0.7570

Flame 3

0.0616

0.0264

0.3

Flame 4

0.0440

0.0440

0.5

3 4 5 6 7 8 9 10 11 12 13 14 15 18


Page 19 of 24

1

Figures

2 3 4 5 6 7 0.14

O2

C2H4(X2)

H2O

0.12

Mole fraction

0.10

CO

0.08

H2

0.06 0.04

CO2

0.02 0.00

C2H5OH

-0.02 0

1

8

2

3

4

HAB(mm)

9 10 11 12 13 14 15 16 17

Figure 1. Mole fraction profiles of reactants and major products in Flame 4 (Symbols: experiment, black solid lines: modeling in present work, red dashed lines: modeling in literature 16 ).

18 1.0

2000

0.8 1500

Flame 1 Flame 2 Flame 3 Flame 4 Temperature Flame 1 (Expt) Flame 4 (Expt)

0.6

0.4

0.2

1000

Temperature (K)

Normalized mole fraction

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

Energy & Fuels

500 0.0 0.0

19 20 21 22 23 24

0.5

1.0

1.5

2.0

HAB (mm)

Figure 2. Measured temperature profile for Flame 1, and calculated (for 4 flames) and measured (for Flames 1 and 4) normalized mole fraction profiles of ethylene.

19


Energy & Fuels

1 2 3 1.0

Normalized mole fraction

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

Flame 1 Flame 4 Flame 1(-48K) Flame 1(-82K)

0.8

0.6

0.4

0.2

0.0 0.0

0.5

1.0

5 6 7 8 9

1.5

2.0

HAB (mm)

4

Figure 3. Normalized mole fraction profiles of ethylene for Flame 4 and 1 at different flame temperatures.

C2H5+O2=C2H4+HO2 C2H4+O=CH2HCO+H nC3H7(+M)=C2H4+CH3(+M) C2H4+O=CH3+HCO C2H4+OH=C2H4OH

Flame 4 Flame 3 Flame 2 Flame 1

C2H4+OH=C2H3+H2O C2H4+H(+M)=C2H5(+M) -1.0

-0.5

10 11

0.0

0.5

1.0

Fractional contribution

(a) Ethylene

12 C2H5OH(+M)=C2H5+OH(+M) C2H5OH+O=CH3CHOH+OH C2H5OH+CH3=CH3CHOH+CH4 C2H5OH+HO2=CH3CHOH+H2O2 C2H5OH+H=CH3CHOH+H2 C2H5OH+OH=C2H4OH+H2O

Flame 4 Flame 3 Flame 2

C2H5OH+OH=CH3CHOH+H2O C2H5OH+OH=CH3CH2O+H2O

13 14 15

-0.4

-0.2

0.0

0.2

0.4

0.6

0.8

1.0


(b) Ethanol Figure 4. ROP and ROD analyses of C2H4 and ethanol at HAB = 0.3 mm. 20


Page 20 of 24

Page 21 of 24

1 2 3 6.0x10-7 Flame 1 Flame 2 Flame 3 Flame 4

Mole fraction

5.0x10-7 4.0x10-7 3.0x10-7 2.0x10-7 1.0x10-7 0.0 0.25

0.30

4 5 6

0.35

HAB (mm)

(a) H

1.0x10-6


-7

Mole fraction

8.0x10

6.0x10-7 4.0x10-7 -7

2.0x10

0.0 0.25

7 8 9 10 11

0.30

0.35

HAB (mm)

(b) OH

Figure 5. Calculated H and OH profiles in the vicinity of HAB = 0.3 mm.

1.0

Normalized mole fraction or ROD

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

Energy & Fuels

0.8

0.6

0.4

rF rS

0.2

0.0

r2 r3 r4 0.1

12 13 14 15

0.2

0.3

0.4

0.5

Initial ethanol fraction in fuel

Figure 6. Normalized mole fractions and consumption reaction rates of C2H4 at HAB = 0.3 mm.

21


Energy & Fuels

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

1 2 3 4 5 6 CH3+HO2=CH3O+OH C2H5+HO2=CH3CH2O+OH HO2+H=2OH HOC2H4O2=2CH2O+OH CH2HCO+O2=CH2O+CO+OH CH2O+OH=HCO+H2O C2H4+OH=C2H3+H2O OH+H2=H+H2O C2H5OH+OH=C2H4OH+H2O


C2H5OH+OH=CH3CHOH+H2O C2H5OH+OH=CH3CH2O+H2O C2H4+OH=C2H4OH -0.4

7 8

-0.2

0.0

0.2

0.4

0.6


Figure 7. ROP and ROD analyses of OH at HAB = 0.3 mm.

9 10 11 12 C2H4+H=C2H3+H2

C2H4+OH=C2H3+H2O

C2H4+O=CH3+HCO

C2H4+O=CH2HCO+H


CH2*+C2H4=aC3H5+H

C2H4+CH3=C2H3+CH4 -0.5

13 14

-0.4

-0.3

-0.2

-0.1

0.0


Figure 8. ROD analyses of C2H4 at HAB = 0.8 mm.

15 16 17 18 19 20 21 22 23 24 22


Page 22 of 24

Page 23 of 24

1

Mole fraction

3.2x10-4

2.8x10-4

2.4x10-4


2.0x10-4

1.6x10-4 0.75

3 4 5

0.80

0.85

HAB (mm)

2

(a) H

6.5x10-5 6.0x10-5

Mole fraction

5.5x10-5 5.0x10-5 4.5x10-5


4.0x10-5 3.5x10-5 0.75

7 8 9

0.80

0.85

HAB (mm)

6 (b) OH

2.0x10-5 1.8x10-5

Mole fraction

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

Energy & Fuels

1.6x10-5 Flame 1 Flame 2 Flame 3 Flame 4

1.4x10-5 1.2x10-5 1.0x10-5 0.75

0.80

0.85

HAB (mm)

10 11

(c) O

12 13 14

Figure 9. Calculated H, OH and O profiles in the vicinity of HAB = 0.8 mm.

23


Energy & Fuels

1.0

Normalized mole fraction or ROD

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

0.9

0.8

0.7

0.6

rF rS r9 r2 r4+10 0.1

1 2 3 4 5 6

0.2

0.3

0.4

0.5

Initial ethanol mole fraction in the fuel

Figure 10. Normalized mole fractions and consumption reaction rates of C2H4 at HAB = 0.8mm.

C2H5OH+H=CH3CHOH+H2 C2H5OH+H=C2H4OH+H2 C2H5OH(+M)=C2H4+H2O(+M) C2H5OH+OH=CH3CH2O+H2O C2H5OH+H=CH3CH2O+H2 C2H5OH(+M)=CH3+CH2OH(+M) C2H5OH+O=CH3CHOH+OH C2H5OH+O=CH3CH2O+OH C2H5OH+OH=CH3CHOH+H2O C2H5OH+CH3=CH3CHOH+CH4

Flame 4 Flame 3 Flame 2

C2H5OH+OH=C2H4OH+H2O C2H5OH+O=C2H4OH+OH C2H5OH+CH3=C2H4OH+CH4 -0.2

7 8

-0.1

0.0


Figure 11. ROD analyses of ethanol at HAB = 0.8 mm.

9

24


Page 24 of 24

Effect of Ethanol on Ethylene Consumption in Premixed Laminar

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