A high-pressure rapid compression machine study of n-propylbenzene ignition

Abstract

This study presents new ignition delay data recorded in a rapid compression machine over a wide range temperature, pressure and fuel/air ratio. This data is an extension of that recorded previously (D. Darcy, C.J. Tobin, K. Yasunaga, J.M. Simmie, J. Würmel, T. Niass, O. Mathieu, S.S. Ahmed, C.K. Westbrook, H.J. Curran, Combust. Flame, 159 (2012) 2219-2232 for the oxidation of n-propylbenzene in a high-pressure shock tube. The data was obtained for equivalence ratios of 0.29, 0.48, 0.96, and 1.92, at compressed gas pressures of 10, 30 and 50 atm, and over the temperature range of 650-1000 K. Experimental data was also obtained at 50 atm for all equivalence ratios in our new heated high-pressure shock tube and this is also presented here. Agreement between the data obtained in both the rapid compression machine and in the shock tube facilities showed excellent complementarity. A previously published chemical kinetic mechanism has been updated in attempt to simulate ignition delay times at the lower temperature conditions of this study by adding the appropriate species and reactions including alkyl-peroxyl and hydroperoxy-alkyl radical chemistry. In general, good agreement was obtained between the model and experiments and consistent trends were observed * address: Combustion Chemistry Centre, School of Chemistry, NUI Galway, Ireland. Phone: 00353-91-493856. Email: henry.curran@nuigalway.ie URL: http://c3.nuigalway.ie/ (H.J. Curran)Preprint submitted to Combustion and Flame February 5, 2013 and these are discussed. Comparisons are also made with experimental data obtained for n-butylbenzene over the same range of conditions and common trends are highlighted. It was found that, in general, n-butylbenzene was faster to ignite over the lower temperature range of 650-1000 K.

An ignition delay and kinetic modeling study of methane, dimethyl ether, and their mixtures at high pressures

“…It has a twin opposed piston configuration. The heating system has been described by Darcy et al [43]. Pressure profiles are recorded using a pressure transducer (Kistler 603B) with the signal passing through a charge amplifier and recorded on a digital oscilloscope.…”

An experimental and modeling study of shock tube and rapid compression machine ignition of n-butylbenzene/air mixtures

“…The sub-mechanism for these polycyclic aromatic species has been derived from the Narayanaswamy et al mechanism [12]. A more detailed discussion on the changes introduced in the toluene submechanism can be found in [44].…”

“…As described in our recent n-propylbenzene paper [44], the addition reactions of the benzyl radical to molecular oxygen, an important step in the low temperature mechanisms of alkylbenzenes in general, have been derived by fitting over the temperature range of interest (600-900 K) the reaction rates that have been theoretically calculated by Murakami et al [46] for the xylyl + O 2 system. The reaction rate for the concerted elimination of HȮ 2 radical from the alkylperoxy species have been derived from Altarawneh et al [47], as in [44].…”

Reactions of HO2 with n-propylbenzene and its phenylpropyl radicals

“…Thus, congeners of alkyl aromatics may serve as surrogates replicating intrinsic chemical and physical properties of real fuels [1,2]. In particular, n-propylbenzene (nPB) embodies well the properties of a class of alkyl benzenes in jet and diesel fuels [3,4]. Previous studies have targeted several combustion characteristics of nPB, including ignition delay [5], laminar burning velocity [6] and sooting tendency [7].…”

“…As a consequence of scarcity of kinetic measurements pertinent to reactions of nPB with C x H y and O/H radicals, the studies adopted the reaction rate constants from analogous oxidation systems such as propane, ethylbenzene and toluene. In reference to thermal decomposition and pyrolysis of nPB, Robinson and Lindstedt reported theoretically-derived rate constants for abstraction of an H atom from the propyl side chain in nPB, by H and CH 3 radicals [14]. Darcy et al [4] predicted the oxidation mechanism of nPB at low temperature to be greatly influenced by the reaction sequence: RH + HO 2 → R + H 2 O 2 , H 2 O 2 + M → 2OH + M. The authors have shown that at 1000 K, HO 2 and benzyl radicals govern the overall oxidation reactivity of nPB.…”