Reviewing the evolution and application of kinetic reaction mechanisms

When researchers use kinetics to understand and predict the chemical behavior of reactive systems, the basic tool connecting the kinetics and the reactive system is the reaction mechanism. The characteristics and capabilities of current kinetic reaction mechanisms are the product of a great deal of directed evolution, which is motivated by the need to be able to model the behavior of practical fuels in real engines. Though most practical fuels are composite fuels, previous fuel research studies have focused on only one fuel at a time, and the leading solution is to use surrogate mixtures—multi-component mixtures of fuels that include at least one example from each class of fuel molecules present in the “real” fuel—to mimic real fuel mixtures.

In a paper recently featured on the cover of a special issue of Physical Chemistry Chemical Physics, Charlie Westbrook, Marco Mehl, William Pitz, Goutham Kukkadapu, Scott Wagnon, and Kuiwen Zhang (all Materials Science Division) trace the evolution of kinetic reaction mechanisms and the applications of those models to real engines as an exercise in understanding the unusual and powerful features of a new class of surrogate mechanisms that can address many different fuel types. Through the review, they also briefly illustrate the capabilities of current models, which have greater functionality than past models.

The paper illustrates that previous work, as well as collaboration with other Office of Science Gas Phase Chemical Physics program researchers, has helped bridge the gap between fundamental and applied research and has advanced the state of kinetic models so they are more accurate in predicting ignition and other combustion behavior.

[C.K. Westbrook, M. Mehl, W.J. Pitz, G. Kukkadapu, S. Wagnon, and K. Zhang, Multi-fuel surrogate chemical kinetic mechanisms for real world applications, Phys. Chem. Chem. Phys. 20, 10588 (2018), doi: 10.1039/C7CP07901J.]