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Air Flame (air + flame)
Selected AbstractsDimensionality estimate of the manifold in chemical composition space for a turbulent premixed H2 + air flame,INTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 6 2004Shaheen R. Tonse The dimensionality () of manifolds of active chemical composition space has been measured using three different approaches: the Hausdorff geometrical binning method, Principal Component Analysis, and the Grassberger-Procaccia cumulative distribution method. A series of artificial manifolds is also generated using a Monte Carlo approach to discern the advantages and limitations of the three methods. Dimensionality is quantified for different levels of turbulent intensity in a simulation of the interactions of a 2D premixed hydrogen flame with a localized region of turbulence superimposed over the cold region upstream of the flame front. The simulations are conducted using an adaptive mesh refinement code for low Mach number reacting flows. By treating the Ns species and temperature of the local thermo-chemical state as a point in multidimensional chemical composition space, a snapshot of a flame region is mapped into chemical composition space to generate the manifold associated with the 2-D flame system. An increase in was observed with increasing turbulent intensity for all three methods. Although each method provides useful information, the Grassberger-Procaccia method is subject to fewer artifacts than the other two thereby providing the most reliable quantification of . © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36: 326,336, 2004 [source] Hydrogen utilization as a fuel: hydrogen-blending effects in flame structure and NO emission behaviour of CH4,air flameINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 5 2007Jeong Park Abstract Hydrogen-blending effects in flame structure and NO emission behaviour are numerically studied with detailed chemistry in methane,air counterflow diffusion flames. The composition of fuel is systematically changed from pure methane to the blending fuel of methane,hydrogen through H2 molar addition up to 30%. Flame structure, which can be described representatively as a fuel consumption layer and a H2,CO consumption layer, is shown to be changed considerably in hydrogen-blending methane flames, compared to pure methane flames. The differences are displayed through maximum flame temperature, the overlap of fuel and oxygen, and the behaviours of the production rates of major species. Hydrogen-blending into hydrocarbon fuel can be a promising technology to reduce both the CO and CO2 emissions supposing that NOx emission should be reduced through some technologies in industrial burners. These drastic changes of flame structure affect NO emission behaviour considerably. The changes of thermal NO and prompt NO are also provided according to hydrogen-blending. Importantly contributing reaction steps to prompt NO are addressed in pure methane and hydrogen-blending methane flames. Copyright © 2006 John Wiley & Sons, Ltd. [source] Numerical studies on the reaction of carbon particles in a vacuum residue,air flameINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 9 2006Ho Young Park Abstract A computational work was carried out for the study of one-dimensional, laminar, premixed, flat, atomized vacuum residue (VR) particle,air flames. The mathematical model includes the specified pyrolysis scheme, soot and char oxidation scheme. With some experimental works, the product composition and kinetic parameters of VR pyrolysis were determined and used for the present computational work. The computed results show that the oxidation of VR carbon char and soot occurs mainly in the reaction zone and the oxidation rate of soot is much higher than that of VR carbon char. The oxidation rates of carbon char and soot can be increased with the decrease in particle diameter, and it might be accomplished by the more effective atomization and mixing of solid particles with combustion air. Copyright © 2005 John Wiley & Sons, Ltd. [source] Computational economy improvements in PRISMINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 9 2003Shaheen R. Tonse The Piecewise Reusable Implementation of Solution Mapping (PRISM) procedure is applied to reactive flow simulations of (9-species) H2 + air combustion. PRISM takes the solution of the chemical kinetic ordinary differential equation system and parameterizes it with quadratic polynomials. To increase the accuracy, the parameterization is done piecewise, by dividing the multidimensional chemical composition space into hypercubes and constructing polynomials for each hypercube on demand. The polynomial coefficients are stored for subsequent repeated reuse. Initial cost of polynomial construction is expensive, but it recouped as the hypercube is reused, hence computational gain depends on the degree of hypercube reuse. We present two methods that help us to identify hypercubes that will ultimately have high reuse, this being accomplished before the expense of constructing polynomials has been incurred. One method utilizes the rate of movement of the chemical trajectory to estimate the number of steps the trajectory would make through the hypercube. The other method defers polynomial construction until a preset threshold of reuse has been met; an empirical method which, nevertheless, produces a substantial gain. The methods are tested on a 0-D chemical mixture and reactive flow 1-D and 2-D simulations of selected laminar and turbulent H2 + air flames. The computational performance of PRISM is improved by a factor of about 2 for both methods. © 2003 Wiley Periodicals, Inc., Int J Chem Kinet 35: 438,452, 2003 [source] Numerical studies on the reaction of carbon particles in a vacuum residue,air flameINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 9 2006Ho Young Park Abstract A computational work was carried out for the study of one-dimensional, laminar, premixed, flat, atomized vacuum residue (VR) particle,air flames. The mathematical model includes the specified pyrolysis scheme, soot and char oxidation scheme. With some experimental works, the product composition and kinetic parameters of VR pyrolysis were determined and used for the present computational work. The computed results show that the oxidation of VR carbon char and soot occurs mainly in the reaction zone and the oxidation rate of soot is much higher than that of VR carbon char. The oxidation rates of carbon char and soot can be increased with the decrease in particle diameter, and it might be accomplished by the more effective atomization and mixing of solid particles with combustion air. Copyright © 2005 John Wiley & Sons, Ltd. [source] Intracavity Laser Absorption Spectroscopy for flame diagnosticsISRAEL JOURNAL OF CHEMISTRY, Issue 2 2007Igor Rahinov Intracavity Laser Absorption Spectroscopy (ICLAS) is one of the most sensitive techniques in absorption spectroscopy. Application of this technique to combustion diagnostics offers many important advantages. Since ICLAS is an absorption-based method, it is not limited by the quenching and predissociation effects that compromise the sensitivity of Laser Induced Fluorescence (LIF), one of the most sensitive and widespread techniques applied in combustion diagnostics. For that reason, radicals that are subject to strong collisional quenching or predissociation, such as 1CH2 and HCO, can be measured by ICLAS with sensitivity much greater than that of LIF. For the same reason, ICLAS also possesses better sensitivity for NH and HNO. The present paper overviews the ICLAS measurements performed during the last decade in our laboratory and also presents recent results: first-time detection of the HSO radical in flames by ICLAS and application of Fiber Laser Intracavity Absorption Spectroscopy (FLICAS) based on Er-doped fiber laser for in-situ detection of ammonia and hydrogen cyanide in a low-pressure methane/air flame doped with a small amount of ammonia. Avenues for future research are discussed. [source] | ||||||||||