Experimental study of the effect of CF3I addition on the ignition delay time and laminar flame speed of methane, ethylene, and propane
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© 2014 The Combustion Institute. Published by Elsevier Inc. All rights reserved. Since no suitable replacement has been found for Halon 1301 (CF3Br), the approach for the next generation of fire suppressants has been to identify diverse agents or blends of agents for specific applications. Halon 13001 (CF3I) is a possible candidate for unoccupied areas. However, there are very few fundamental data to help in validating its detailed kinetics mechanism. In this study, ignition delay time and laminar flame speed measurements of the effects of CF3I on CH4, C2H4, and C3H8 have been investigated for the first time. The ignition delay times were obtained in a shock tube with mixtures of fuel/O2/CF3I highly diluted in 98% argon (vol.), and the flame speeds were measured using an expanding, spherical flame. Results from the new experiments show a significant decrease in the laminar flame speed for small additions of suppressant. The effects on the ignition delay time are strongly dependent on the hydrocarbon: the ignition delay time of CH4 is significantly decreased by CF3I addition, while a significant increase in the ignition delay time was observed for the lowest temperatures investigated with C2H4. Ignition delay times for C3H8 were mostly unchanged, except for the lowest temperatures (below 1400 K) where a small decrease in the reactivity was observed. Compared to recent results obtained with CF3Br, CF3I showed a smaller suppressant effect under the conditions investigated. A detailed kinetics mechanism assembled from a C1-C3 mechanism from NUI Galway and a CF3I sub-mechanism from NIST predicts well the results obtained in the shock tube with CH4 and C3H8. The C2H4 data with CF3I are however poorly predicted, pointing at some deficiencies in the model for C2H4/CF3I interactions.
author list (cited authors)
Mathieu, O., Goulier, J., Gourmel, F., Mannan, M. S., Chaumeix, N., & Petersen, E. L.