Hydrogen autoignition at pressures above the second explosion limit (0.6-4.0 MPa)

a b s t r a c tThe feasibility of developing multipurpose reduced chemistry that is able to describe, with sufficient accuracy, premixed and non-premixed flames, one-dimensional detonations, high-temperature autoignition, and also low-temperature autoignition is explored. A four-step mechanism with O and OH in steady state is thoroughly tested and is shown to give satisfactory results under all conditions. The possibility of reducing this to a three-step mechanism, to decrease computation times without compromising the range of applicability is then investigated. The originality of this work resides in introducing a single species X, representing either HO 2 for high-temperature ignition or H 2 O 2 for low-temperature ignition. An algorithm is defined that covers the entire range without significant degradation of accuracy. Integrations show promising results for different laminar test cases, and applicability to turbulent flows is indicated.

Section: Introductionmentioning

confidence: 99%

Four-step and three-step systematically reduced chemistry for wide-range H2–air combustion problems

Boivin

Sánchez

Williams

2013

“…Lee and Hochgreb at the Massachusetts Institute of Technology (MIT) used an air driven, oil damped RCF piston system [20] to study hydrogen auto-ignition [21]. Lee and Hochgreb have performed detailed modeling of the suppression of vortices, which are formed by the piston in this facility during compression, and the heat transfer that occurs within the MIT RCF [22].…”

Section: Introductionmentioning

confidence: 99%

Demonstration of a free-piston rapid compression facility for the study of high temperature combustion phenomena

Donovan

Zigler

et al. 2004

A free-piston rapid-compression facility (RCF) has been developed at the University of Michigan (UM) for use in studying high-temperature combustion phenomena, including gasphase combustion synthesis and homogeneous charge compression ignition systems. The facility is designed to rapidly compress a mixture of test gases in a nearly adiabatic process. A range of compression ratios, currently 16 to 37, can be obtained. The high temperatures and pressures generated by the RCF can be maintained for in excess of 50 ms, providing an order of magnitude increase in observation time over what can be obtained using shock tubes. The facility is instrumented for temperature and pressure measurements as well as optical access for use with laser and other optical diagnostics. This work describes the UM-RCF and its operation, establishes obtainable pressures and temperatures (over 1900 kPa and 970 K for predominately N 2 gas mixtures, and over 785 kPa and 2000 K for Ar gas mixtures), and demonstrates the repeatability of the UM-RCF experiments (< 3% run-to-run variability in peak pressure) for combustion studies. The experimental results for time histories of temperature and pressure are interpreted using analytical isentropic models. Comparison between the isentropic predictions and the experimental data indicate excellent agreement and support the conclusion that the core region of the test gases is nominally uniform and is compressed isentropically.2

“…The design for these creviced piston heads was originally devised at MIT [20,21,22], who found that the temperature field obtained using creviced pistons is almost homogeneous compared to that obtained using flat piston heads which is predicted to lead to far greater gas in-homogeneities in the post-compressed combustion chamber. A computational fluid dynamics (CFD) study carried out at NUI Galway [23] supports this view.…”

Section: Rapid Compression Machinementioning

confidence: 99%

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

Darcy

Nakamura

Tobin

et al. 2014

103

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.