Title: The Development of a Detailed Chemical Kinetic Mechanism for Diisobutylene and Comparison to Shock Tube Ignition Times

Abstract

There is much demand for chemical kinetic models to represent practical fuels such as gasoline, diesel and aviation fuel. These blended fuels contain hundreds of components whose identity and amounts are often unknown. A chemical kinetic mechanism that would represent the oxidation of all these species with accompanying chemical reactions is intractable with current computational capabilities, chemical knowledge and manpower resources. The use of surrogate fuels is an approach to make the development of chemical kinetic mechanisms for practical fuels tractable. A surrogate fuel model consists of a small number of fuel components that can be used to represent the practical fuel and still predict desired characteristics of the practical fuel. These desired fuel characteristics may include ignition behavior, burning velocity, fuel viscosity, fuel vaporization, and fuel emissions (carbon monoxide, hydrocarbons, soot and nitric oxides). Gasoline consists of many different classes of hydrocarbons including n-alkanes, alkenes, iso-alkanes, cycloalkanes, cycloalkenes, and aromatics. One approach is to use a fuel surrogate that has a single component from each class of hydrocarbon in gasoline so that the unique molecular structure of each class is represented. This approach may lead to reliable predictions of many of the combustion properties of the practical fuel. Inmore » order to obtain a fuel surrogate mechanism, detailed chemical kinetic mechanisms must be developed for each component in the surrogate. In this study, a detailed chemical kinetic mechanism is developed for diisobutylene, a fuel intended to represent alkenes in practical fuels such as gasoline, diesel, and aviation fuel. The fuel component diisobutylene usually consists of a mixture of two conjugate olefins of iso-octane: 1- or 2-pentene, 2,4,4-trimethyl. Diisobutylene has a similar molecular structure to iso-octane, so that its kinetics offers insight into the effect of including a double bond in the carbon skeletal structure of iso-octane. There are few previous studies on diisobutylene. Kaiser et al. [1] examined the exhaust emission from a production spark ignition engine with neat diisobutylene and with it mixed with gasoline. They found the exhaust emissions of diisobutylene to be similar to that of iso-octane. They saw a significant increase in the amount of 2-methyl-1,3-butadiene measured in the exhaust of the engine. They also found appreciable amount of propene in the exhaust, but could not explain the source of this product as they did others in terms of C-C bond beta scission of alkyl radicals. Risberg et al. [2] studied a number of fuel blends to evaluate their autoignition quality for use in a homogeneous charge compression ignition engine, using diisobutylene to represent olefins in one of their test fuels. In this study, experiments on the shock tube ignition of both isomers of diisobutylene will be described. Then, the development of a detailed chemical kinetic mechanism for the two isomers of diisobutylene will be discussed.« less

Authors:

Metcalfe, W; Curran, H J; Simmie, J M; Pitz, W J; Westbrook, C K

Publication Date:

Fri Jan 21 00:00:00 EST 2005

Research Org.:

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

Sponsoring Org.:

US Department of Energy (US)

OSTI Identifier:

15011577

Report Number(s):

UCRL-CONF-209210
Journal ID: ISSN 1540-7489; TRN: US200507%%560

DOE Contract Number:  

W-7405-ENG-48

Resource Type:

Conference

Resource Relation:

Journal Volume: 31; Journal Issue: 1; Conference: Presented at: 2005 Joint Meeting of the U.S. Sections of the Combustion Institute, Philadelphia, PA (US), 03/20/2005--03/23/2005; Other Information: PBD: 21 Jan 2005

Country of Publication:

United States

Language:

English

Subject:

30 DIRECT ENERGY CONVERSION; 33 ADVANCED PROPULSION SYSTEMS; 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ALKENES; ALKYL RADICALS; CHEMICAL REACTIONS; COMBUSTION; COMBUSTION PROPERTIES; DOUBLE BONDS; EVAPORATION; HYDROCARBONS; IGNITION; ISOMERS; KINETICS; MOLECULAR STRUCTURE; PROPYLENE; SHOCK TUBES; SPARK IGNITION ENGINES