Experimental Study of the Addition Effects of CF_3I on the Oxidation Properties of Light Hydrocarbons

摘要

Halon 13001 (CF_3I) is a possible candidate for CF_3Br replacement in unoccupied areas. In this study, the effects of CF_3I addition on the ignition delay time (τ_(ign)) and laminar flame speed of CH_4, C_2H_4, and C_3H_8 have been investigated. The ignition delay times were obtained in a shock tube, and the flame speeds were measured using an expanding, spherical flame. Results show a significant decrease in the laminar flame speed for small CF_3I additions. The effects on τ_(ign) are strongly dependent on the hydrocarbon: the ignition delay time of CH_4 is significantly decreased by CF_3I addition, while a significant increase in τ_(ign) was observed for the lowest temperatures investigated with C_2H_4. Ignition delay times for C_3H_8 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 CF_3Br, CF_3I showed a smaller suppressant effect under the conditions investigated. A detailed kinetics mechanism assembled from a C1-C3 mechanism from NUI Galway and a CF_3I sub-mechanism from NIST predicts well the results obtained in the shock tube with CH_4 and C_3H_8. The C_2H_4 data with CF_3I are however poorly predicted, pointing at some deficiencies for C_2H_4/CF_3I interactions.