Computer Construction of Detailed Chemical Kinetic Models for Gas-Phase Reactors

Abstract

The combustion, oxidation, and pyrolysis chemistry of even simple light hydrocarbons can be extremely complex, involving hundreds or thousands of kinetically significant species. Even relatively minor species can play an important role in the formation of undesirable emissions and byproducts, and their properties and reactions need to be modeled in some detail in order to make accurate predictions. In many technologically important applications, the reaction chemistry is closely coupled with the mixing and heat flow, dramatically increasing the computational difficulty. The most reasonable way to deal with this complexity is to use a computer not only to solve the simulation numerically, but also to construct the model in the first place. We are developing the methods needed to make this sort of computer-aided kinetic modeling feasible for real systems. The computer is used to calculate most of the molecular properties and rate parameters in the model by a variety of quantum- and group-additivity-based techniques. We summarize our new computer methods for modeling the pressure dependence (falloff and chemical activation) of gas-phase reactions. Our approach to determining the optimal reduced kinetic models for various reaction conditions is discussed. Adaptive-chemistry methods that allow one to solve detailed macroscopic reacting flow simulations involving hundreds of species are outlined.

Recent progress in the development of diesel surrogate fuels

“…An alternative to reducing the size of the detailed mechanism is to save computational time by pre-calculating the chemistry and using table lookups [108]. Mechanism reduction can be done "on the fly" during a reacting flow calculation, so that much smaller mechanisms can be used at different times and locations on the computational grid [109,110]. There are other ways to reduce computational times.…”

Ab initio group contribution method for activation energies for radical additions

“…Building a kinetic model based on elementary reactions for such processes is a computationally challenging task. Several groups have worked on algorithms for the automated generation of complex reaction networks (Hillewaert et al, 1988;Susnow et al, 1997;De Witt et al, 2000;Wauters and Marin, 2001;Green et al, 2001;Matheu et al, 2001). Besides the demanding task to generate such networks, these kinetic models require the input of a large amount of generally unknown fundamental kinetic and thermodynamic parameters.…”

Reduction of Single Event Kinetic Models by Rigorous Relumping: Application to Catalytic Reforming

“…, hydrocarbon oxidation and combustion (Chevalier et al, 1990(Chevalier et al, , 1992Ranzi et al 1995;Blurock, 1995; Côme et al, 1996;Gaffuri et al, 1997;Glaude et al, 1997Glaude et al, , 1998Iyer et al, 1998;Warth et al, 2000;Battin-Leclerc et al, 2000;Green et al, 2001;Matheu et al, 2001;Németh et al, 2002; Truong, 2003, 2006;Song et al, 2003; Katare et al, 2004;Buda et al, 2006; Pfaendtner and Broadbelt, 2008a, b), isomerization (Guillaume et al, 2003;Surla et al, 2011), alkylation (Martinis and Froment, 2006), olefin oligomerization and alkylation (Prickett and Mavrovouniotis, 1997c; Guillaume, 2006; Shahrouzi et al, 2008), propane aromatization (Katare et al, 2004) catalytic reforming (Joshi et al, 1999; Klein et al, 2006;Wei et al, 2008; Sotelo-Boyás and Froment, 2009), catalytic cracking (Feng et al, 1993;Prickett and Mavrovouniotis, 1997a;Joshi et al, 1997Joshi et al, , 1998 …”