Detailed Chemical Kinetics of Alkane Combustion

Paraffin wax is a great candidate for use as a hybrid rocket fuel. It burns three to four times faster than conventional polymer fuels, increasing thrust, and is non-toxic, which makes its transport safer and cheaper. However, hybrid rocket motors are not yet well-understood, and this limits ability to control combustion burning mode and the underlying thermo-chemical and mechanical behavior at the fuel-oxidizer interface. To address this challenge, we propose to extend the detailed chemical kinetic reaction mechanisms to treat large paraffin hydrocarbon fuels. This is part of a larger effort to achieve greater insight into ignition and combustion performance of these fuels (Center for Hybrid Rocket Exascale Simulation, or CHREST (www.buffalo.edu/chrest ).

Hundreds of thousands of elementary chemical reactions could potentially be involved in the combustion of paraffin fuel. The fact that only a small fraction of these are critically important to describe the overall combustion process creates a need to systematically generate a reaction mechanism and identify core reaction pathways in an automated fashion. We propose to use the Reaction Mechanism Generator (RMG, rmg.mit.edu/) tool to determine the relevant core species and identify key reactions. Apart from obtaining estimates of reaction kinetics using rate rules and group-additivity estimates of thermochemical properties, we will conduct a sensitivity analysis with respect to reaction rate coefficients.

A reliable combustion mechanism that successfully identifies key reactions and estimates their kinetics and equilibria would be a major advance over available models.