Hydrogen- and C₁–C₃ Hydrocarbon-Nitrous Oxide Kinetics in Freely Propagating and Burner-Stabilized Flames, Shock Tubes, and Flow Reactors

Abstract

A detailed, chemical mechanism has been compiled for modeling the combustion of C ₁–C ₃ hydrocarbon-nitrous oxide mixtures. The compiled, chemical mechanism has been compared and validated against available data in the literature, including flame structure measurements of hydrogen-nitrous oxide and ammonia-nitrous oxide flames, flow reactor data on hydrogen-nitrous oxide and moist, nitrous oxide decomposition mixtures, shock tube ignition delay data on hydrogen- and methane-nitrous oxide mixtures, experimental flame speed data on carbon monoxide-nitrous oxide mixtures, and experimental, laminar flame speed data for hydrogen-, methane-, acetylene-, and propane-nitrous oxide mixtures. Feature sensitivity studies and reaction path analyses have been employed to elucidate important pathways to the overall reaction rate for these systems, and include the nitrous oxide decomposition step (N ₂ O(+M) ⇌ N ₂ + O(+M)) and nitrous oxide reactions with H atoms (N ₂ O + H ⇌ N ₂ + OH and N ₂ O + H ⇌ NH + NO). Modifications to the compiled mechanism were considered on the basis of the most sensitive reactions with the highest apparent rate constant uncertainty, to closely predict the various experimental data considered.

Keywords:

• Chemical kinetics
• Nitrous oxide mixture

ACKNOWLEDGMENTS

Financial support from AFRL/RZA is gratefully acknowledged. The authors also would like to thank Prof. Anthony Dean for his fruitful insights and suggestions and Prof. P. Glarborg for kindly providing an electronic copy of the latest chemical mechanism developed by his group.

Notes

^a Rate represented as sum of two Arrhenius expressions.

†Low-pressure limit rate.

Specific reaction rate constants have the form k = A T ⁿ  exp (−E _a /RT). Units are cm³, cal, mol, and sec, and Reference refers to reference for the Current mechanism.

^a Low pressure limit rate.

The views expressed in this article are those of the authors and do not reflect the official policy or position of the United States Air Force, Department of Defense, or the U.S. Government.