摘要:

The ignition of 2-methyl-pentane, was modeled and compared to experiments of ignition delay time in a shock-tube, using n-pentane, 2-methyl-pentane and n-hexane in mixtures with oxygen diluted with argon. The product distribution of the preignited mixtures were also investigated and numerical modeling of the combustion kinetics was performed. The 2-methyl-pentane (2MP) experiments were run at temperatures of 1175 to 1772 K and pressures of 2 to 4.6 atmospheres. The numerical modeling of 2MP was performed with a large kinetic scheme containing 430 elementary reactions, and then reduced to a scheme containing 110 reactions only.

ISSN:0010-2202    

DOI:10.1080/00102209908924210

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The combustion of a liquid fuel floating on water is a problem of interest because of its potential environmental and safety consequences. When a liquid fuel is burning under these conditions, the presence of the water may cause some particular effects due to heat transfer to the water. If the fuel layer is thin, heat losses to the water may cause quenching of the fuel burning. If the fuel layer is sufficiently thick, it is possible for the heat transferred to the water to induce nucleate boiling of the water and, in turn, splashing of the fuel above, a phenomenon referred to as thin-layer boilover. In this work, a one-dimensional, transient, heat transfer model of a burning liquid fuel floating on water is developed, and applied to predict the temperature histories in the fuel and water layers, and the time for the onset of boilover. The model includes in-depth radiation absorption but neglects convection within the liquid, and assumes that boilover occurs when the temperature at the fuel/water interface reaches a critical value above the water saturation temperature. Experimental measurements previously made by the authors with different multicomponent. and single composition fuels (crude and healing oil, and several parafines) were used to derive the heal flux at the fuel surface, and an average radiation absorption coefficient, which are two parameters needed as input in the model. It is shown that the model correctly predicts, within the uncertainty of the experiments, the influence of the major parameters of the problem, specifically the initial fuel layer thickness, the pool diameter, and fuel boiling point, on the temperature history of the fuel and water and time to the start of boilover. The effect of the fuel boiling point appears to be complex because a change in boiling point is accompanied by a change in burning rate, surface heat flux, in-depth absorption, and viscosity, all affecting the boilover phenomenon. The model represents a significant improvement from the quasi-steady heat conduction models previously developed by the present and other investigators of the boilover phenomenon.

ISSN:0010-2202    

DOI:10.1080/00102209908924211

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A detailed reaction mechanism of n-heptane combustion has been elaborated and validated by comparison of computed mole fraction profiles with those measured in four premixed flames stabilized on a flat-flame burner under low pressure )6 kPa). in a wide range of equivalence ratios (0.7 - 2.0). As the MBMS technique was used for species analyses, both stable and active species were considered. The predictions of the model are in good agreement with the experimental results for most stable species. The main active species H. OH and O are fairly well predicted in rich flames while disagreements are observed in the lean and the stoichiometric flames. The intermediate radicals can be grouped in three classes depending on the accuracy of the model predictions: (i) good agreement in Ihe whole range of equivalence ratios, (ii) predicted mole fractions differing from the experimental values by a constant factor in the four flames studied, (iii) difference between computed and measured maximum mole fractions differing from lean to rich flames. In the discussion of the results, the observed disagreements between the model and the experiments have been generally interpreted in term of experimental inaccuracies. However, the modeling of the combustion chemistry for heavy fuel molecules has been carried out so far on the basis of experimental data referring only to stable species and the problems faced with intermediate radicals can result from experimental uncertainties but also from deficiencies in the mechanism or inaccuracies in the kinetic data.

ISSN:0010-2202    

DOI:10.1080/00102209908924212

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor