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Annual Report to Sponsor: Understanding Unwanted Combustion Enhancement by Potential Halon Replacements

Published

Author(s)

Gregory T. Linteris, Jeffrey A. Manion, Donald R. Burgess Jr., Iftikhar A. Awan, Peter B. Sunderland, John L. Pagliaro

Abstract

This year, we continued work to numerically model the behavior of the Halon replacements in the FAA Aerosol Can Test (FAA-ACT) to understand why they are causing more overpressure rather than flame extinction. The goal is to understand the process to determine if a solution is possible with clean agent halon replacements, and if so, to guide development of such replacements (if none already exist). The major accomplishments this year include ... ... 1. Developed starting kinetic mechanisms for Novec and 2-BTP in flames (the former based on simple analogies and estimated rates; the latter through detailed experiments and quantum mechanical calcalations of reaction rates). These are at a state where they can be used, but will invariably be updated as we exercise their capabilities and learn their limitations. 2. Performed thermodynamic equilibrium and stirred-reactor calculations for Novec over a range of conditions of the FAA Aerosol Can Test. The results for Novec were very similar to those of HFC-125, and supported all of the postulates from last year. In particular: a.) Novec (which interacts with the fire ball) completely decomposes and adds energy to the system. b.) The pressure rise in the FAA-ACT can be predicted for Novec based on equilibrium thermodynamics (asssuming diffusion flame behavior and complete reaction). c.) For Novec at all concentrations tested (sub-inerting) in the FAA test, there appear to be no kinetic limitations to its complete reaction. d.) For Novec and HFC-125, stirred reactor calculations are predicting behavior consistent with the cup-burner extinction conditions for these agents. 3. Performed laminar premixed burning velocity calculations (PREMIX ) for HFC-125 for the range of conditions of the FAA-ACT. The predictions were consistent with those from the stirred reactor calcualtions, and illustrate that the FAA-ACT is consuming reactants under conditions for which the burning velocity is in the range
Citation
OTHER -

Keywords

Fire Suppression, Flame Inhibition, CF3Br, C2HF5, Halon Replacements, Cargo-Bay Fire Suppression

Citation

Linteris, G. , Manion, J. , Burgess, D. , Awan, I. , Sunderland, P. and Pagliaro, J. (2012), Annual Report to Sponsor: Understanding Unwanted Combustion Enhancement by Potential Halon Replacements, Other, National Institute of Standards and Technology, Gaithersburg, MD (Accessed May 29, 2023)
Created February 3, 2012, Updated February 19, 2017