Experimental and modeling study of the kinetics of oxidation of ethanol-n-heptane mixtures in a jet-stirred reactor

Fuel 89 (2010) 280–286

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Experimental and modeling study of the kinetics of oxidation of ethanol-n-heptane mixtures in a jet-stirred reactor Philippe Dagaut *, Casimir Togbé CNRS, 1c, Avenue de la Recherche, Scientifique, 45071 Orléans, cedex 2, France

a r t i c l e

i n f o

Article history: Received 6 February 2009 Received in revised form 26 June 2009 Accepted 30 June 2009 Available online 15 Julty 2009 Keywords: Oxidation Kinetics Modeling Gasoline Ethanol

a b s t r a c t The kinetics of oxidation of ethanol-n-heptane mixtures (20–80 and 50–50 mol.%) was studied experimentally using a fused-silica jet-stirred reactor. The experiments were performed in the temperature range 530–1070 K, at 10 atm, at two equivalence ratios (0.5 and 1), and with an initial fuel concentration of 750 ppm. A kinetic modeling was performed using schemes resulting from the merging of validated kinetic schemes for the oxidation of the components of the present mixtures (n-heptane and ethanol). Good agreement between the experimental results and the computations was observed under the present conditions when using detailed chemistry whereas the used of semi-detailed chemistry yielded acceptable but less accurate prediction of the fuel oxidation kinetics. Ó 2009 Elsevier Ltd. All rights reserved.

1. Introduction The use of fossil fuels for ground transportation vehicles contributes to a dramatic increase of atmospheric pollution and fossil CO2 emission. During the last two decades the incorporation of non-fossil compounds in automotive fuels [1–6] has increased [5]. Nowadays, mixtures of conventional gasoline with ethanol is used worldwide [4] and most of the engine manufacturers propose ‘flex-fuel’ engines that can run with E10 or E85 (10 or 85 vol.% of ethanol with petrol–gasoline). Meanwhile, many recent studies concern the use of ethanol with a variety of new engine technologies [7–9]; the interpretation of the results needs validated kinetic schemes based on simple laboratory experiments. Also, the increasing use of ethanol in automotive fuels is a source of concerns since engine emissions containing relatively large amounts of ethanol and acetaldehyde may be very harmful [10–16]. Therefore, kinetic data and chemical kinetic schemes are essential for modeling the combustion of such oxygenated fuels. While the oxidation of pure hydrocarbons has been the topic of many studies [17], only few focused on the oxidation of hydrocarbons–oxygenates mixtures [18–21]. Also, the oxidation of ethanol was the subject of numerous studies [22,23], whereas that of its co-oxidation with hydrocarbons was not [8,19]. Therefore, new inputs into experimental databases are still needed to propose and validate chemical kinetic models for the combustion of such oxygenated

* Corresponding author. Tel.: +33 238 25 54 66; fax: +33 238 69 60 04. E-mail address: [email protected] (P. Dagaut). 0016-2361/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.fuel.2009.06.035

fuel mixtures. Since commercial fuels are complex mixtures of thousands hydrocarbons, it is usually necessary to use surrogate model fuels to describe their combustion chemistry [19,20,24–28]. As part of a continuing effort in this laboratory to improve the knowledge of fuel combustion kinetics and provide the needed inputs for future modeling, we (i) performed experiments on the oxidation of ethanol-blended fuels in a jet-stirred reactor (JSR) and (ii) proposed a kinetic model representing the data. Since several kinetic schemes for n-heptane oxidation are available in the literature, two of them (a detailed scheme [29] and a derived reduce scheme [30]) were merged with a previously used kinetic subscheme for the oxidation of ethanol and its mixture with a surrogate gasoline [19]. The experimental and modeling results obtained in the present study are reported in the next sections. 2. Experimental A spherical JSR similar to that used previously [19,20,31] was used. It was located inside a regulated electrical resistance oven of 1.5 kW, surrounded by ceramic insulating material and a pressure–resistant stainless steel jacket, allowing operation up to 10 atm. Ethanol absolute grade (99.9% pure, Riedel – de Haën) and n-heptane (>99% pure, Aldrich) were mixed after ultrasonic degassing. The fuel mixture was pumped, using a micro piston HPLC pump (Shimadzu LC-120 ADvp) and an on-line degasser (Shimadzu DGU-20 A3), and sent to an in-house stainless steel atomizer–vaporizer assembly maintained at 175 °C. A flow of nitrogen (50 L/h) was used for the atomization. All the gases were regulated by thermal mass-flow controllers. The oxygen (99.995% pure) flow

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was diluted by a flow of nitrogen (<50 ppm of O2; <1000 ppm of Ar; <5 ppm of H2). This O2/N2 flow was mixed with the fuel–nitrogen flow just before the entrance of the injectors, after preheating at temperatures close to the working temperature. Residence time distribution studies showed that in the present conditions, the reactor is operating under macro-mixing conditions [31]. As before [31,32], a good thermal homogeneity was observed along the vertical axis of the reactor by thermocouple measurements (Pt/Pt–Rh 10%, 0.1 mm diameter located inside a thin-wall fused-silica tube to prevent catalytic reactions on the wires). Typical temperature gradients of <2 K/cm were measured. Since we operated under a high degree of dilution, the temperature rise due to the reaction was generally
negative sign) and production (R with a positive sign) were computed for every species. 4. Results and discussion In this work we studied the oxidation of two ethanol–heptane mixture (20–80 and 50–50 mol.%). The composition of the reacting mixtures is given in Table 1. The oxidation of these mixtures at 10 atm was performed in a JSR that was chosen to be able to investigate the oxidation of the fuels over their main oxidation regimes (cool flame, negative temperature coefficient, high temperature). The flows were adapted to keep this mean residence time constant whereas the operating temperature was varied stepwise. During the JSR experiments, ca. 15 species were identified and measured by GC/MS, FID, and TCD. Experimental mole fractions as a function of temperature were obtained for H2, H2O, O2, CO, CO2, CH2O, CH4, C2H6, C2H4, C2H2, ethanol, acetaldehyde (ethanal), C3H6, 1-C4H8, 1C5H10, 1-C6H12. The data indicate that the rates of consumption of ethanol and n-heptane are very similar when these two components have the same initial mole fraction in the fuel (Fig. 1) whereas in the case of the ethanol/heptane 20/80 mol.% mixture, the rate of consumption of n-heptane is ca. 4 times higher than that of ethanol (Fig. 2), in line with their initial concentrations in the fuel. Ethanol with its high-octane number is not prone to oxidize through a cool flame reaction mechanism. However, in presence of n-heptane (low octane number, RON = 0) ethanol can oxidize thanks to the pool of radicals provided via the oxidation of n-heptane. Figs. 3–10 shows examples of the present experimental results compared to the computations. It can be noticed from Figs. 3–6 that the semi-detailed model does not accurately represent the mole fractions of the fuel components and of the main products. Figs. 7–10 present comparisons between the present experimental data and the simulations using the detailed scheme. As can be seen from these figures, the detailed model represents well the consumption of the fuels as well as the intermediate formation of hydrocarbons and oxygenates, and that of final products. For this reason, we used the detailed scheme in reaction paths analyses to delineate the main oxidation reaction paths of the fuel by computing normalized rates of production (R with a positive sign) and consumption (R with a negative sign) for every species. For the 20/80 fuel mixture, in stoichiometric conditions and low temperature (640 K), ethanol mostly reacts with OH and HO2: 2501. C2H5OH + OH <=> CH2CH2OH + H2O; R(C2H5OH) = 0.1 2502. C2H5OH+OH <=> CH3CHOH + H2O; R(C2H5OH) = 0.846 2503. C2H5OH + OH <=> CH3CH2O + H2O; R(C2H5OH) = 0.03 2513. C2H5OH + HO2 <=> CH3CHOH + H2O2; R(C2H5OH) = 0.016 n-C7H16 reacts via H-atom abstraction with OH, forming mainly 2- and 3-heptyl radicals: 2107. 2108. 2109. 2110.

n-C7H16 + OH <=> C7H15–1 + H2O; n-C7H16 + OH <=> C7H15–2 + H2O; n-C7H16 + OH <=> C7H15–3 + H2O; n-C7H16 + OH <=> C7H15–4 + H2O;

C2H4 is mainly alkylhydroperoxyde

Table 1 Experimental conditions. Mixture (ethanol/n-heptane in mole%)

Equivalence ratio

Initial mole fractions Ethanol

n-Heptane

Oxygen

20–80 20–80 50–50 50–50

1 0.5 1 0.5

0.000150 0.000150 0.000375 0.000375

0.000600 0.000600 0.000375 0.000375

0.00705 0.01410 0.00525 0.01050

formed

by

R(n-C7H16) = R(n-C7H16) = R(n-C7H16) = R(n-C7H16) =

decomposition

0.16 0.32 0.32 0.16 of

the

540. C2H4O2H <=> C2H4 + HO2; R(C2H4) = 0.42 988. C2H5O2 <=> C2H4 + HO2; R(C2H4) = 0.198 2554. C2H5 + O2 <=> C2H4 + HO2; R(C2H4) = 0.198 CH3CHO is produced through the decomposition of ketohydroperoxides and oxidation of CH3CHOH:

1e-4

2e-5 1e-5

50/50

1e-6 500

=0.5

R(EtOH) R(Heptane)

2e-6

600

700

800

900

Rate of consumption in mole/L/s

P. Dagaut, C. Togbé / Fuel 89 (2010) 280–286

Rate of consumption in mole/L/s

282

1000 1100

1e-4

2e-5 1e-5

50/50

1e-6 500

=1

R(EtOH) R(Heptane)

2e-6

600

700

800

900

1000 1100

T/K

T/K

1e-4

4e-5 3e-5 2e-5

1e-5 500

20/80 =0.5 R(EtOH) R(Heptane)

600

700

800

900

1000 1100

Rate of consumption in mole/L/s

Rate of consumption in mole/L/s

Fig. 1. The experimental rates of oxidation of ethanol and n-heptane during the oxidation of the ethanol/heptane 50/50 mol.% fuel mixture in a JSR at 10 atm, 700 ms, and u = 0.5 and 1 (rate of consumption = 1/t (X0 X) (P/RxT) where t is the mean residence time, X0 and X represent the initial and measured mole fractions of fuel, P is the operating pressure (10 atm), T the temperature in K, and R = 0.082 L atm/mol).

1e-4

2e-5 1e-5

20/80

2e-6 1e-6 500

=1

R(EtOH) R(Heptane)

600

700

800

900

1000 1100

T/K

T/K

Fig. 2. The experimental rates of oxidation of ethanol and n-heptane during the oxidation of the ethanol/heptane 20/80 mol.% fuel mixture in a JSR at 10 atm, 700 ms, and u = 0.5 and 1.

0.002

0.002 EtOH H O 2

0.0015

Mole Fraction

Mole Fraction

0.0015

CO CO 2 Heptane

0.001

0.001

5e-4

5e-4

0 500

EtOH H2O CO CO2 Heptane

600

700

800

900

1000 1100

T/K Fig. 3. The oxidation of an ethanol/heptane 20/80 mol.% fuel mixture in a JSR at 10 atm, 700 ms, and u = 0.5. Comparison between experimental results (symbols) and semi-detailed modeling (lines and small symbols).

1364. n-C4KET13 <=> CH3CHO + CH2CHO + OH; R(CH3CHO) = 0.1 2356. n-C7KET42 <=> CH3CHO + n-C3H7COCH2 + OH; R(CH3CHO) = 0.38 2523. CH3CHOH + O2 <=> CH3CHO + HO2; R(CH3CHO) = 0.224 2524. CH3CHOH + O2 <=> CH3CHO + HO2; R(CH3CHO) = 0.087 CH2O is produced through decomposition and oxidation reactions with molecular oxygen:

0 500

600

700

800

900

1000 1100

T/K Fig. 4. The oxidation of an ethanol/heptane 20/80 mol.% fuel mixture in a JSR at 10 atm, 700 ms, and u = 1. Comparison between experimental results (symbols) and semi-detailed modeling (lines and small symbols).

35. CH3O(+M) <=> CH2O + H(+M); R(CH2O) = 0.078 39. CH3O+O2 <=> CH2O + HO2; R(CH2O) = 0.18 77. CH2OH+O2 <=> CH2O + HO2; R(CH2O) = 0.085 504. O2C2H4OH <=> OH2 + CH2O; R(CH2O) = 0.137 979. CH3COCH2O <=> CH3CO + CH2O; R(CH2O) = 0.19 2563. CH2CHO+O2 <=> CH2O + CO + OH; R(CH2O) = 0.143 At higher temperature (820 K) where ca. 50% of the fuel is consumed, ethanol still reacts predominantly with OH:

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0.002

Mole Fraction

0.0015

C2H4 is mostly produced through the decomposition of small alkyl radicals formed during n-heptane oxidation:

EtOH H2O CO CO2 Heptane

137. n-C3H7 <=> CH3 + C2H4; R(C2H4) = 0.147 224. 1-C4H9 <=> C2H5 + C2H4; R(C2H4) = 0.184 540. C2H4O2H <=> C2H4 + HO2; R(C2H4) = 0.12 988. C2H5O2 <=> C2H4 + HO2; R(C2H4) = 0.09 2554. C2H5+O2 <=> C2H4 + HO2; R(C2H4) = 0.29

0.001

5e-4

CH3CHO is mostly produced via the reactions of CH3CH2O and CH3CHOH: 0 500

600

700

800

900

1000 1100

678. C4H7O <=> CH3CHO + C2H3; R(CH3CHO) = 0.15 2516. CH3CH2O + M <=> CH3CHO + H + M; R(CH3CHO) = 0.07 2523. CH3CHOH + O2 <=> CH3CHO + HO2; R(CH3CHO) = 0.43 2524. CH3CHOH + O2 <=> CH3CHO + HO2; R(CH3CHO) = 0.05

T/K Fig. 5. The oxidation of an ethanol/heptane 50/50 mol.% fuel mixture in a JSR at 10 atm, 700 ms, and u = 0.5. Comparison between experimental results (symbols) and semi-detailed modeling (lines and small symbols).

CH2O is mainly produced via methoxy decomposition: 0.002

Mole Fraction

0.0015

35. CH3O(+M) <=> CH2O + H(+M); R(CH2O) = 0.368 104. C2H3 + O2 <=> CH2O + HCO; R(CH2O) = 0.2 527. C3H5O <=> C2H3 + CH2O; R(CH2O) = 0.084 2563. CH2CHO + O2 <=> CH2O + CO + OH; R(CH2O) = 0.076

EtOH H2O CO CO2 Heptane

For the 50/50 fuel mixture, in stoichiometric conditions and low temperature (640 K), ethanol mostly reacts by H-atom abstraction with OH and HO2:

0.001

5e-4

0 500

600

700

800

900

2501. 2502. 2503. 2513.

1000 1100

T/K

whereas n-C7H16 reacts mainly with OH:

Fig. 6. The oxidation of an ethanol/heptane 50/50 mol.% fuel mixture in a JSR at 10 atm, 700 ms, and u = 1. Comparison between experimental results (symbols) and semi-detailed modeling (lines and small symbols).

2107. 2108. 2109. 2110.

2501. C2H5OH + OH <=> CH2CH2OH + H2O; R(C2H5OH) = 0.104 2502. C2H5OH + OH <=> CH3CHOH + H2O; R(C2H5OH) = 0.703

EtOH CH2O H2 Heptane C2H4

Mole Fraction

6e-4

4e-4

R(n-C7H16) = R(n-C7H16) = R(n-C7H16) = R(n-C7H16) =

1.5e-4

0.154 0.27 0.27 0.136

0.004

CH4 CH3CHO C3H6

0.003

1e-4

5e-5

2e-4

0 500

1 + H2O; 2 + H2O; 3 + H2O; 4 + H2O;

R(n-C7H16) = R(n-C7H16) = R(n-C7H16) = R(n-C7H16) =

0.16 0.32 0.32 0.16

540. C2H4O2H <=> C2H4 + HO2; R(C2H4) = 0.424 988. C2H5O2 <=> C2H4 + HO2; R(C2H4) = 0.203 2554. C2H5 + O2 <=> C2H4 + HO2; R(C2H4) = 0.2

Mole Fraction

8e-4

1 + H2O; 2 + H2O; 3 + H2O; 4 + H2O;

Mole Fraction

n-C7H16 + OH <=> C7H15 n-C7H16 + OH <=> C7H15 n-C7H16 + OH <=> C7H15 n-C7H16 + OH <=> C7H15

n-C7H16 + OH <=> C7H15 n-C7H16 + OH <=> C7H15 n-C7H16 + OH <=> C7H15 n-C7H16 + OH <=> C7H15

Ethylene is formed through decomposition of peroxy and alkylhydroperoxy, and oxidation of ethyl by O2:

and n-C7H16 still reacts with OH: 2107. 2108. 2109. 2110.

C2H5OH + OH <=> CH2CH2OH + H2O; R(C2H5OH) = 0.1 C2H5OH + OH <=> CH3CHOH + H2O; R(C2H5OH) = 0.844 C2H5OH + OH <=> CH3CH2O + H2O; R(C2H5OH) = 0.03 C2H5OH + HO2 <=> CH3CHOH + H2O2; R(C2H5OH) = 0.02

CO CO2 H2O

0.002

0.001

600

700

800

T/K

900

1000 1100

0 500

600

700

800

T/K

900

1000 1100

0 500

600

700

800

900

1000 1100

T/K

Fig. 7. The oxidation of an ethanol/heptane 20/80 mol.% fuel mixture in a JSR at 10 atm, 700 ms, and u = 0.5. Comparison between experimental results (symbols) and detailed modeling (lines and small symbols).

P. Dagaut, C. Togbé / Fuel 89 (2010) 280–286

Mole Fraction

8e-4

2e-4

EtOH CH2O H2 Heptane C2H4

1.5e-4

Mole Fraction

0.001

6e-4 4e-4

600

700

800

900

1e-4

0 500

1000 1100

CO CO2 H2O

0.003

5e-5

2e-4 0 500

0.004

CH4 CH3CHO C3H6

Mole Fraction

284

0.002

0.001

600

700

T/K

800

900

0 500

1000 1100

600

700

T/K

800

900

1000 1100

T/K

Fig. 8. The oxidation of an ethanol/heptane 20/80 mol.% fuel mixture in a JSR at 10 atm, 700 ms, and u = 1. Comparison between experimental results (symbols) and detailed modeling (lines and small symbols).

Mole Fraction

4e-4 3e-4 2e-4

1.5e-4

0.004

CH4 CH3CHO C3H6

1e-4

5e-5

0.002

0.001

1e-4 0 500

CO CO2 H2O

0.003

Mole Fraction

EtOH CH2O H2 Heptane C2H4

Mole Fraction

5e-4

600

700

800

900

0 500

1000 1100

600

700

T/K

800

900

0 500

1000 1100

600

700

800

900

1000 1100

T/K

T/K

Fig. 9. The oxidation of an ethanol/heptane 50/50 mol.% fuel mixture in a JSR at 10 atm, 700 ms, and u = 0.5. Comparison between experimental results (symbols) and detailed modeling (lines and small symbols).

2e-4

Mole Fraction

Mole Fraction

4e-4 3e-4 2e-4 1e-4 0 500

EtOH CH2O H2 Heptane C2H4

600

700

1.5e-4

0.003

CH4 CH3CHO C3H6

0.0025

Mole Fraction

5e-4

1e-4

CO CO2 H2O

0.002 0.0015 0.001

5e-5 5e-4

800

900

1000 1100

0 500

600

700

T/K

800

T/K

900

1000 1100

0 500

600

700

800

900

1000 1100

T/K

Fig. 10. The oxidation of an ethanol/heptane 50/50 mol.% fuel mixture in a JSR at 10 atm, 700 ms, and u = 1. Comparison between experimental results (symbols) and detailed modeling (lines and small symbols).

CH3CHO is mainly produced through the reaction of CH3CHOH with O2, 2523. CH3CHOH + O2 <=> CH3CHO + HO2; R(CH3CHO) = 0.467 2524. CH3CHOH + O2 <=> CH3CHO + HO2; R(CH3CHO) = 0.18 The importance of these routes increased by a factor of ca. 2 compared to the ethanol/n-heptane 20/80 mixture case, in line with the increased initial concentration of ethanol in the fuel. This is the most noticeable change in the reaction paths for the oxida-

tion of the 20/80 and the 50/50 fuel mixtures. CH2O is formed through 35. CH3O(+M) <=> CH2O + H(+M); R(CH2O) = 0.1 39. CH3O + O2 <=> CH2O + HO2; R(CH2O) = 0.185 504. O2C2H4OH <=> OH + 2CH2O; R(CH2O) = 0.16 979. CH3COCH2O <=> CH3CO + CH2O; R(CH2O) = 0.197 At higher temperature (820 K) where ca. 50% of the fuel is consumed, the reaction paths change. Ethanol mainly reacts with OH, and to some extent with HO2:

P. Dagaut, C. Togbé / Fuel 89 (2010) 280–286

2501. C2H5OH + OH <=> CH2CH2OH + H2O; R(C2H5OH) = 0.1 2502. C2H5OH + OH <=> CH3CHOH + H2O; R(C2H5OH) = 0.7 2513. C2H5OH + HO2 <=> CH3CHOH + H2O2; R(C2H5OH) = 0.1 n-C7H16 still reacts with OH yielding 1- to 4-heptyl radicals: 2107. 2108. 2109. 2110.

n-C7H16 + OH <=> C7H15 n-C7H16 + OH <=> C7H15 n-C7H16 + OH <=> C7H15 n-C7H16 + OH <=> C7H15

1 + H2O; 2 + H2O; 3 + H2O; 4 + H2O;

R(n-C7H16) = R(n-C7H16) = R(n-C7H16) = R(n-C7H16) =

0.15 0.27 0.27 0.135

C2H4 is mainly produced by alkyl radicals decomposition and oxidation of ethyl radicals: 137. n-C3H7 <=> CH3 + C2H4; R(C2H4) = 0.156 224. 1-C4H9 <=> C2H5 + C2H4; R(C2H4) = 0.185 540. C2H4O2H <=> C2H4 + HO2; R(C2H4) = 0.114 988. C2H5O2 <=> C2H4 + HO2; R(C2H4) = 0.085 2161. C7H15 1 <=> C5H11-1 + C2H4; R(C2H4) = 0.078 2554. C2H5 + O2 <=> C2H4 + HO2 0.2; R(C2H4) = 0.27 The formation of acetaldehyde occurs via: 678. C4H7O <=> CH3CHO + C2H3; R(CH3CHO) = 0.06 2523. CH3CHOH + O2 <=> CH3CHO + HO2; R(CH3CHO) = 0.71 2524. CH3CHOH + O2 <=> CH3CHO + HO2; R(CH3CHO) = 0.086 whereas that of CH2O mainly results from methoxy radicals decomposition: 35. CH3O(+M) <=> CH2O + H(+M); R(CH2O) = 0.423 104. C2H3 + O2 <=> CH2O + HCO; R(CH2O) = 0.168 527. C3H5O <=> C2H3 + CH2O; R(CH2O) = 0.07 2563. CH2CHO + O2 <=> CH2O + CO + OH; R(CH2O) = 0.09 5. Conclusion The two main objectives of this study were achieved: (i) New data consisting of concentration profiles of reactants, stable intermediates, and final products were obtained as a function of reaction temperature for the oxidation of ethanol–heptane mixtures in a JSR at 10 atm and 700 ms for fuel-lean and stoichiometric mixtures; (ii) a chemical kinetic modeling of these experiments was performed using two mechanism derived from the literature. The more detailed mechanism permitted a good representation of the present data. It was used to delineate the main routes involved in the oxidation of the fuel mixtures. The two fuel compositions (ethanol/n-heptane 20/80 and 50/ 50 mol.%) used showed very similar oxidation reaction paths besides the increased importance of acetaldehyde production via the oxidation of CH3CHOH with increasing ethanol initial concentration. The semi-detailed scheme gave a reasonable representation of the present data and could probably be useful for future engine modeling where limiting the size of the chemical model is still of paramount importance. Finally, in the future, 1-butanol may also be used as a biofuel component of gasoline. The present work could be extended to that of butanol–heptane fuel mixtures [40].

Appendix A. Supplementary data Supplementary data associated with this article can be found, in the online version, at doi:10.1016/j.fuel.2009.06.035.

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References [1] Barker T, Bashmakov I, Bernstein L, Bogner JE, Bosch PR, Dave R, Davidson OR, Fisher BS, Gupta S, Halsns K, Heij GJ, Kahn Ribeiro S, Kobayashi S, Levine MD, Martino DL, Masera O, Metz B, Meyer LA, Nabuurs G-J, Najam A, Nakicenovic N, Rogner H-H, Roy J, Sathaye J, Schock R, Shukla P, Sims REH, Smith P, Tirpak DA, Urge-Vorsatz D, Zhou D. Technical summary. In: Climate change 2007: mitigation. Contribution of working group III to the fourth assessment report of the intergovernmental panel on climate change. Cambridge, United Kingdom and New York, NY, USA: Cambridge University Press; 2007. [2] Fontaras G, Samaras Z. A quantitative analysis of the European Automakers’ voluntary commitment to reduce CO2 emissions from new passenger cars based on independent experimental data. Energy Policy 2007;35:2239–48. [3] Iliuc I. EU objective of 120 g CO2/km emission for new cars, a challenge for tribology. Math Comput Biol Chem 2008:66–71. [4] Jeuland N, Montagne X, Gautrot X. Potentiality of ethanol as a fuel for dedicated engine. Oil Gas Sci Technol – Rev De L’Inst Francais Du Petrole 2004;59:559–70. [5] Low SA, Isserman AM. Ethanol and the local economy industry trends, location factors, economic impacts, and risks. Econ Dev Q 2009;23:71–88. [6] Singh A, Gangopadhyay S, Nanda PK, Bhattacharya S, Sharma C, Bhan C. Trends of greenhouse gas emissions from the road transport sector in India. Sci Total Environ 2008;390:124–31. [7] Sayin C, Uslu K. Influence of advanced injection timing on the performance and emissions of CI engine fueled with ethanol-blended diesel fuel. Int J Energy Res 2008;32:1006–15. [8] Lu XC, Hou YC, Zu LL, Huang Z. Experimental study on the auto-ignition and combustion characteristics in the homogeneous charge compression ignition (HCCI) combustion operation with ethanol/n-heptane blend fuels by port injection. Fuel 2006;85:2622–31. [9] Hou YC, Lu XC, Zu LL, bin Ji L, Huang Z. Effect of high-octane oxygenated fuels on n-heptane-fueled HCCI combustion. Energy Fuels 2006;20:1425–33. [10] Winebrake JJ, Wang MQ, He DQ. Toxic emissions from mobile sources: a total fuel-cycle analysis for conventional and alternative fuel vehicles. J Air Waste Manage Assoc 2001;51:1073–86. [11] Jacobson MZ. Effects of ethanol (E85) versus gasoline vehicles on cancer and mortality in the United States. Environ Sci Technol 2007;41:4150–7. [12] Kim S, Dale BE. Ethanol fuels: E10 or E85 – Life cycle perspectives. Int J Life Cycle Assess 2006;11:117–21. [13] Farrell AE, Plevin RJ, Turner BT, Jones AD, O’Hare M, Kammen DM. Ethanol can contribute to energy and environmental goals. Science 2006;311:506–8. [14] Magnusson R, Nilsson C, Andersson B. Emissions of aldehydes and ketones from a two-stroke engine using ethanol and ethanol-blended gasoline as fuel. Environ Sci Technol 2002;36:1656–64. [15] Niven RK. Ethanol in gasoline: environmental impacts and sustainability review article. Renew Sust Energy Rev 2005;9:535–55. [16] von Blottnitz H, Curran MA. A review of assessments conducted on bio-ethanol as a transportation fuel from a net energy, greenhouse gas, and environmental life cycle perspective. J Cleaner Prod 2007;15:607–19. [17] Simmie JM. Detailed chemical kinetic models for the combustion of hydrocarbon fuels. Prog Energy Combust Sci 2003;29:599–634. [18] Dagaut P, Koch R, Cathonnet M. The oxidation of n-heptane in the presence of oxygenated octane improvers: MTBE and ETBE. Combust Sci Technol 1997;122:345–61. [19] Dagaut P, Togbe C. Experimental and modeling study of the kinetics of oxidation of ethanol–gasoline surrogate mixtures (E85 surrogate) in a jetstirred reactor. Energy Fuels 2008;22:3499–505. [20] Dagaut P, Togbé C. Oxidation kinetics of butanol–gasoline surrogate mixtures in a jet-stirred reactor: experimental and modeling study. Fuel 2008;87:3313–21. [21] Song JO, Yao CD, Liu SY, Xu HJ. Effects of ethanol addition on n-heptane decomposition in premixed flames. Energy Fuels 2008;22:3806–9. [22] Leplat N, Seydi A, Vandooren J. An experimental study of the structure of a stoichiometric ethanol/oxygen/argon flame. Combust Sci Technol 2008;180:519–32. [23] Saxena P, Williams FA. Numerical and experimental studies of ethanol flames. Proc Combust Inst 2007;31:1149–56. [24] Yahyaoui M, Djebaili-Chaumeix N, Dagaut P, Paillard CE, Gail S. Experimental and modelling study of gasoline surrogate mixtures oxidation in jet stirred reactor and shock tube. Proc Combust Inst 2007;31:385–91. [25] Mati K, Ristori A, Gail S, Pengloan G, Dagaut P. The oxidation of a diesel fuel at 1–10 atm: experimental study in a JSR and detailed chemical kinetic modeling. Proc Combust Inst 2007;31:2939–46. [26] Dagaut P, El Bakali A, Ristori A. The combustion of kerosene: experimental results and kinetic modelling using 1- to 3-component surrogate model fuels. Fuel 2006;85:944–56. [27] Dagaut P, Cathonnet M. The ignition, oxidation, and combustion of kerosene: a review of experimental and kinetic modeling. Prog Energy Combust Sci 2006;32:48–92. [28] Dagaut P, Gail S. Chemical kinetic study of the effect of a biofuel additive on Jet-A1 combustion. J Phys Chem A 2007;111:3992–4000. [29] Curran HJ, Gaffuri P, Pitz WJ, Westbrook CK. A comprehensive modeling study of n-heptane oxidation. Combust Flame 1998;114:149–77. [30] Seiser R, Pitsch H, Seshadri K, Pitz WJ, Curran HJ. Extinction and autoignition of n-heptane in counterflow configuration. Proc Combust Inst 2000;28:2029–37.

286

P. Dagaut, C. Togbé / Fuel 89 (2010) 280–286

[31] Dagaut P, Cathonnet M, Rouan JP, Foulatier R, Quilgars A, Boettner JC, Gaillard F, James H. A jet-stirred reactor for kinetic-studies of homogeneous gas-phase reactions at pressures up to 10-atmospheres (1 MPa). J Phys E-Sci Instrum 1986;19:207–9. [32] Dayma G, Hadj Ali K, Dagaut P. Experimental and detailed kinetic modeling study of the high pressure oxidation of methanol sensitized by nitric oxide and nitrogen dioxide. Proc Combust Inst 2007;31:411–8. [33] Dubreuil A, Foucher F, Mounaim-Rousselle C, Dayma G, Dagaut P. HCCI combustion: effect of NO in EGR. Proc Combust Inst 2007;31:2879–86. [34] Glarborg P, Kee RJ, Grcar JF, Miller JA. PSR: A FORTRAN program for modeling well-stirred reactors. SAND86-8209. Livermore, CA: Sandia National Laboratories; 1986. [35] Park J, Xu ZF, Lin MC. Thermal decomposition of ethanol. II. A computational study of the kinetics and mechanism for the H + C[sub 2]H[sub 5]OH reaction. J Chem Phys 2003;118:9990–6.

[36] Xu S, Lin MC. Theoretical study on the kinetics for OH reactions with CH3OH and C2H5OH. Proc Combust Inst 2007;31:159–66. [37] Xu ZF, Park J, Lin MC. Thermal decomposition of ethanol. III. A computational study of the kinetics and mechanism for the CH[sub 3]+ C[sub 2]H[sub 5]OH reaction. J Chem Phys 2004;120:6593–9. [38] Wu CW, Lee YP, Xu SC, Lin MC. Experimental and theoretical studies of rate coefficients for the reaction O(P-3) plus C2H5OH at high temperatures. J Phys Chem A 2007;111:6693–703. [39] Tan Y, Dagaut P, Cathonnet M, Boettner JC. Acetylene oxidation in a JSR from 1atm to 10-atm and comprehensive kinetic modeling. Combust Sci Technol 1994;102:21–55. [40] Dagaut P, Togbé C. Experimental and modeling study of the kinetics of oxidation of butanol-n-heptane mixtures in a jet-stirred reactor. Energy Fuels 2009. doi:10.1021/ef900261.