Title: Probing the antagonistic effect of toluene as a component in surrogate fuel models at low temperatures and high pressures. A case study of toluene/dimethyl ether mixtures

Abstract

There is a dearth of experimental data which examine the fundamental low-temperature ignition (T < 900 K) behavior of toluene resulting in a lack of data for the construction, validation, and interpretation of chemical kinetic models for commercial fuels. In order to gain a better understanding of its combustion chemistry, dimethyl ether (DME) has been used as a radical initiator to induce ignition in this highly knock resistant aromatic, and its influence on the combustion of toluene ignition was studied in both shock tube and rapid compression machines as a function of temperature (624–1459 K), pressure (20–40 atm), equivalence ratio (0.5–2.0), and blending ratio (100% toluene, 76% toluene (76T/24D), 58% toluene (58T/42D), 26% toluene (26T/74D) and 100% DME). We use several literature chemical kinetic models to interpret our experimental results. For mixtures containing high concentrations of toluene at low-temperatures none of these are capable of reproducing experiment. This then implies an incomplete understanding of the low-temperature oxidation pathways which control its ignition in our experimental reactors, and by extension, in spark- (SI) and compression-ignition (CI) engines, and an updated detailed chemical kinetic model is presented for engineering applications. Model analyses indicate that although the initial fate of the fuel ismore » dominated by single-step H-atom abstraction reactions from both the benzylic and phenylic sites, the subsequent fate of the allylic and vinylic radicals formed is much more complex. Further experimental and theoretical endeavors are required to gain a holistic qualitative and quantitative chemical kinetics based understanding of the combustion of pure toluene, toluene blends, and commercial fuels containing other aromatic components, at temperatures of relevance to SI and CI engines.« less

Authors:

Zhang, Yingjia  ^[1];

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Somers, Kieran P. ^[2]; Mehl, Marco ^[3]; Pitz, William J. ^[3]; Cracknell, Roger F. ^[4]; Curran, Henry J. ^[5]

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+ Show Author Affiliations

1. National Univ. of Ireland, Galway (Ireland). Combustion Chemistry Centre; Xi'an Jiaotong Univ. (China). State Key Lab. of Multiphase Flow in Power Engineering
2. National Univ. of Ireland, Galway (Ireland). Combustion Chemistry Centre; Shell Global Solutions, London (United Kingdom)
3. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
4. Shell Global Solutions, London (United Kingdom)
5. National Univ. of Ireland, Galway (Ireland). Combustion Chemistry Centre

Publication Date:

Tue Jul 12 00:00:00 EDT 2016

Research Org.:

Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

Sponsoring Org.:

USDOE Office of Energy Efficiency and Renewable Energy (EERE), Vehicle Technologies Office (EE-3V); USDOE

OSTI Identifier:

1375997

Alternate Identifier(s):

OSTI ID: 1412971

Report Number(s):

LLNL-JRNL-679773
Journal ID: ISSN 1540-7489; PII: S1540748916302528

Grant/Contract Number:  

AC52-07NA27344

Resource Type:

Accepted Manuscript

Journal Name:

Proceedings of the Combustion Institute

Additional Journal Information:

Journal Volume: 36; Journal Issue: 1; Journal ID: ISSN 1540-7489

Publisher:

Elsevier

Country of Publication:

United States

Language:

English

Subject:

30 DIRECT ENERGY CONVERSION; 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; Shock tube; Rapid compression machine; Ignition delay time; Toluene; Dimethyl ether