The Experts below are selected from a list of 2364 Experts worldwide ranked by ideXlab platform
Filip Verplaetsen - One of the best experts on this subject based on the ideXlab platform.
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calculation of the upper Flammability Limit of methane air mixtures at elevated pressures and temperatures
Journal of Hazardous Materials, 2008Co-Authors: F Van Den Schoor, Filip VerplaetsenAbstract:Four different numerical methods to calculate the upper Flammability Limit of methane/air mixtures at initial pressures up to 10 bar and initial temperatures up to 200 degrees C are evaluated by comparison with experimental data. Planar freely propagating flames are calculated with the inclusion of a radiation heat loss term in the energy conservation equation to numerically obtain Flammability Limits. Three different reaction mechanisms are used in these calculations. At atmospheric pressure, the results of these calculations are satisfactory. At elevated pressures, however, large discrepancies are found. The spherically expanding flame calculations only show a marginal improvement compared with the planar flame calculations. On the other hand, the application of a Limiting burning velocity with a pressure dependence Su,lim approximately p(-1/2) is found to predict the pressure dependence of the upper Flammability Limit very well, whereas the application of a constant Limiting flame temperature is found to slightly underestimate the temperature dependence of the upper Flammability Limit.
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calculation of the upper Flammability Limit of methane hydrogen air mixtures at elevated pressures and temperatures
International Journal of Hydrogen Energy, 2008Co-Authors: F Van Den Schoor, Filip VerplaetsenAbstract:Abstract The results of three different numerical methods to calculate Flammability Limits—namely (1) the calculation of planar flames with the inclusion of a (radiation) heat loss term in the energy conservation equation, and the application of (2) a Limiting burning velocity and of (3) a Limiting flame temperature—are compared with experimental data on the upper Flammability Limit (UFL) of methane/hydrogen/air mixtures with hydrogen fuel molar fractions of 20% and 40%, at initial pressures up to 10 bar and initial temperatures up to 200 °C. The application of a Limiting burning velocity is found to predict the pressure dependence of the UFL well, while the application of a Limiting flame temperature generally is found to slightly underestimate the temperature dependence of the UFL.
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the upper Flammability Limit of methane hydrogen air mixtures at elevated pressures and temperatures
International Journal of Hydrogen Energy, 2007Co-Authors: F Van Den Schoor, Filip VerplaetsenAbstract:Abstract The upper Flammability Limit (UFL) of methane/hydrogen/air mixtures is determined for hydrogen fuel molar fractions of 0%, 20% and 40%, at initial pressures up to 10 bar and initial temperatures up to 200 ∘ C . The experiments are performed in a closed spherical 4.2 dm 3 vessel. The mixtures are ignited by fusing a coiled tungsten wire, placed at the centre of the vessel. A 5% pressure rise criterion is used to determine the Flammability Limits. The results show the UFL to increase with increasing initial pressure, initial temperature and hydrogen fuel concentration. At atmospheric pressure a second experimental set-up is used, to allow comparison between the bomb and tube method as described by European standard EN 1839. It is found that with increasing initial temperature the pressure rise criterion used in the bomb method becomes less sensitive than the visual Flammability criterion used in the tube method.
Farhad Gharagheizi - One of the best experts on this subject based on the ideXlab platform.
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Quantitative Structure−Property Relationship for Prediction of the Lower Flammability Limit of Pure Compounds
2015Co-Authors: Farhad GharagheiziAbstract:A quantitative structure−property relationship (QSPR) study was performed to develop a model for prediction of the lower Flammability Limit (LFL) of pure compounds. The obtained model is a four-parameter multilinear equation. These four parameters are calculated from the chemical structure of every molecule. The average absolute error, squared correlation coefficient, and root mean squares of error of the obtained model over all 1056 pure compounds used to develop the model are 7.68%, 0.9698, and 0.084, respectively
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corresponding states method for estimation of upper Flammability Limit temperature of chemical compounds
Industrial & Engineering Chemistry Research, 2012Co-Authors: Farhad Gharagheizi, Poorandokht Ilanikashkouli, Amir H MohammadiAbstract:The accuracy and predictability of predictive methods to determine the Flammability characteristics of chemical compounds are of drastic significance in the chemical industry. This work aims at continuing application of the gene expression programming (GEP) mathematical strategy to modify the existing thermophysical properties correlations available in the literature to pursue the following objectives: optimization of the number of independent parameters, amplification of the generality, and improvement of the accuracy and predictability. This work deals with presenting a simple corresponding states model to predict the upper Flammability Limit temperature of 1462 organic compounds from 76 chemical families. The parameters of the correlation include the critical temperature and the acentric factor of the compounds. The obtained statistical parameters including average absolute relative deviation of the results from DIPPR 801 database values (1.7, 1.8, 1.7% for training, optimization, and prediction sets, ...
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Corresponding States Method for Estimation of Upper Flammability Limit Temperature of Chemical Compounds
2012Co-Authors: Farhad Gharagheizi, Poorandokht Ilani-kashkouli, Amir H MohammadiAbstract:The accuracy and predictability of predictive methods to determine the Flammability characteristics of chemical compounds are of drastic significance in the chemical industry. This work aims at continuing application of the gene expression programming (GEP) mathematical strategy to modify the existing thermophysical properties correlations available in the literature to pursue the following objectives: optimization of the number of independent parameters, amplification of the generality, and improvement of the accuracy and predictability. This work deals with presenting a simple corresponding states model to predict the upper Flammability Limit temperature of 1462 organic compounds from 76 chemical families. The parameters of the correlation include the critical temperature and the acentric factor of the compounds. The obtained statistical parameters including average absolute relative deviation of the results from DIPPR 801 database values (1.7, 1.8, 1.7% for training, optimization, and prediction sets, respectively) demonstrate improved accuracy of the presented correlations
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chemical structure based model for estimation of the upper Flammability Limit of pure compounds
Energy & Fuels, 2010Co-Authors: Farhad GharagheiziAbstract:In the present work, a new molecular-based model is presented for estimation of the upper Flammability Limit (UFL) of pure compounds. The parameters of the model are the number of occurrences of a new collection of 113 functional groups. On the basis of these 113 functional groups, a feed-forward neural network is presented to estimate the UFL of pure compounds. The squared correlation coefficient, absolute percent error, standard deviation, and root-mean-square error of the model over the 867 pure compounds used for the development of the model are 0.9469, 7.07%, 0.883, 0.882, respectively. Therefore, the model is accurate and can be used to predict the UFL for a wide range of pure compounds.
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prediction of upper Flammability Limit percent of pure compounds from their molecular structures
Journal of Hazardous Materials, 2009Co-Authors: Farhad GharagheiziAbstract:In this study, a quantitative structure-property relationship (QSPR) is presented to predict the upper Flammability Limit percent (UFLP) of pure compounds. The obtained model is a five parameters multi-linear equation. The parameters of the model are calculated only from chemical structure. The average absolute error and squared correlation coefficient of the obtained model over all 865 pure compounds used to develop the model are 9.7%, and 0.92, respectively.
F Van Den Schoor - One of the best experts on this subject based on the ideXlab platform.
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calculation of the upper Flammability Limit of methane air mixtures at elevated pressures and temperatures
Journal of Hazardous Materials, 2008Co-Authors: F Van Den Schoor, Filip VerplaetsenAbstract:Four different numerical methods to calculate the upper Flammability Limit of methane/air mixtures at initial pressures up to 10 bar and initial temperatures up to 200 degrees C are evaluated by comparison with experimental data. Planar freely propagating flames are calculated with the inclusion of a radiation heat loss term in the energy conservation equation to numerically obtain Flammability Limits. Three different reaction mechanisms are used in these calculations. At atmospheric pressure, the results of these calculations are satisfactory. At elevated pressures, however, large discrepancies are found. The spherically expanding flame calculations only show a marginal improvement compared with the planar flame calculations. On the other hand, the application of a Limiting burning velocity with a pressure dependence Su,lim approximately p(-1/2) is found to predict the pressure dependence of the upper Flammability Limit very well, whereas the application of a constant Limiting flame temperature is found to slightly underestimate the temperature dependence of the upper Flammability Limit.
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calculation of the upper Flammability Limit of methane hydrogen air mixtures at elevated pressures and temperatures
International Journal of Hydrogen Energy, 2008Co-Authors: F Van Den Schoor, Filip VerplaetsenAbstract:Abstract The results of three different numerical methods to calculate Flammability Limits—namely (1) the calculation of planar flames with the inclusion of a (radiation) heat loss term in the energy conservation equation, and the application of (2) a Limiting burning velocity and of (3) a Limiting flame temperature—are compared with experimental data on the upper Flammability Limit (UFL) of methane/hydrogen/air mixtures with hydrogen fuel molar fractions of 20% and 40%, at initial pressures up to 10 bar and initial temperatures up to 200 °C. The application of a Limiting burning velocity is found to predict the pressure dependence of the UFL well, while the application of a Limiting flame temperature generally is found to slightly underestimate the temperature dependence of the UFL.
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the upper Flammability Limit of methane hydrogen air mixtures at elevated pressures and temperatures
International Journal of Hydrogen Energy, 2007Co-Authors: F Van Den Schoor, Filip VerplaetsenAbstract:Abstract The upper Flammability Limit (UFL) of methane/hydrogen/air mixtures is determined for hydrogen fuel molar fractions of 0%, 20% and 40%, at initial pressures up to 10 bar and initial temperatures up to 200 ∘ C . The experiments are performed in a closed spherical 4.2 dm 3 vessel. The mixtures are ignited by fusing a coiled tungsten wire, placed at the centre of the vessel. A 5% pressure rise criterion is used to determine the Flammability Limits. The results show the UFL to increase with increasing initial pressure, initial temperature and hydrogen fuel concentration. At atmospheric pressure a second experimental set-up is used, to allow comparison between the bomb and tube method as described by European standard EN 1839. It is found that with increasing initial temperature the pressure rise criterion used in the bomb method becomes less sensitive than the visual Flammability criterion used in the tube method.
Yu Hong Sun - One of the best experts on this subject based on the ideXlab platform.
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the ignitability of coal dust air and methane coal dust air mixtures
Fuel, 1993Co-Authors: Paul R Amyotte, Kenneth J Mintz, Michael J Pegg, Yu Hong SunAbstract:Abstract An experimental investigation of coal dust explosions was conducted in a 26 1 spherical chamber. Channel (mine-face) samples of coal from the Prince and Phalen mines of the Cape Breton Development Corporation were used. The objective of the work was to investigate the ignitability characteristics of the coals, alone and with admixed methane. The apparent lean Flammability Limit of the coal dust-air mixtures was observed to decrease with increasing ignition energy. The decrease was rapid at low energies, with an approach to an asymptotic value of the lean Limit at high energies. A stored ignition energy of 5 kJ was required to measure these asymptotic values which represent the true lean Flammability Limit. The apparent lean Limit at a given ignition energy was found to decrease in the presence of methane, with a reduction in mass mean diameter of the parent coal, and with an increase in coal volatile matter. These three conditions also enhanced the ignitability of the coal dust-air mixtures, meaning that ignition of a given coal dust concentration was possible with lower energies. The lowering of the lean Limit with methane admixture, particle size reduction and increase in volatiles was more pronounced at lower ignition energies.
E Mastorakos - One of the best experts on this subject based on the ideXlab platform.
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temperature and reaction zone imaging in turbulent swirling dual fuel flames
Proceedings of the Combustion Institute, 2019Co-Authors: Michael J Evans, Jennifer A Sidey, J Ye, Paul R Medwell, Bassam B Dally, E MastorakosAbstract:Abstract Gaseous and liquid dual-fuel flames present both a practical approach to emissions reduction and a challenge to current state-of-the-art combustion modelling. This paper uses simultaneously imaged temperature and normalised OH signal fields to investigate flame structure and provide experimental data for model validation across a range of swirl-stabilised n-heptane spray flames. These data are obtained by non-linear excitation regime two-line atomic fluorescence (NTLAF) of indium, and planar laser-induced fluorescence (OH-PLIF), respectively. Swirling gas streams are varied by flowrate (63–88% of blow-off), premixed equivalence ratio (including air-only), and by type of gaseous fuel (natural gas and hydrogen). Results are used to describe how hot combustion products interact with the fuel spray: heating and diluting the region above the apex of the spray cone at low air flowrates but drawing fuel into outer branches of the flame with increasing air flowrates. Adding natural gas to the swirling air stream, at a concentration below the lean Flammability Limit, gives rise to a temperature increase in the outer branches with little effect on the hot region above the apex of the spray, along the burner centreline. The size of this region is significantly reduced; however, using hydrogen. As the concentration of gaseous fuel increases towards the lean Flammability Limit, peak temperatures shift towards the outer branch of the flame. Exceeding the lean Flammability Limit, an additional reaction zone begins to form in the premixed swirling stream, adjacent to the outer branch of the swirl flame. Stable outer branches of the swirl flame, however, become less prevalent and the peak temperatures of the spray flame return to burner centreline. This study provides insight into the complex behaviour of dual-fuel flames, a complementary dataset to related, PLIF-only studies and validation data for the development of numerical modelling tools.