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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Society of Combustion
Journal Basic Information
Journal DOI :
The Korean Society of Combustion
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Volume & Issues
Volume 17, Issue 4 - Dec 2012
Volume 17, Issue 3 - Sep 2012
Volume 17, Issue 2 - Jun 2012
Volume 17, Issue 1 - Mar 2012
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Numerical Study on the 300 MW Shell-type One-stage Entrained Flow Coal Gasifier Apllied with 4-Layer Slagging Model
Hong, Jung-Woo ; Jeong, Hyo-Jae ; Song, Ji-Hoon ; Hwang, Jung-Ho ;
Journal of the Korean Society of Combustion, volume 17, issue 1, 2012, Pages 1~11
A slag building simplified model was developed to determine wall heat flux of a Shell 300 MW coal gasifier. In the model 4 layers(particulate, sintered, molten slag, solidified slag) were considered and mass conservation and energy balance were used to obtain each slag layer's thickness and surface temperature. Thermo-chemical and fluid charateristics of the gasifier were studied with and without considering the slag model using commercial CFD code FLUENT. Consideration of the slag layer did not affect syn-gas mole fractions. However, the slag layer caused to increase the exit gas temperature by about 50 K.
The Experimental Study on Simultaneous Measurements of
Concentration and Temperature of Flue Gas Using a Single Diode Laser
Kim, Se-Won ; Shin, Myoung-Chul ; Lee, Chang-Yeop ; Youn, Sung-Woon ; Kim, Young-Il ;
Journal of the Korean Society of Combustion, volume 17, issue 1, 2012, Pages 12~21
Simultaneous measurements of oxygen concentration and temperature using diode laser in the combustion environment are successfully accomplished. A single DFB type diode laser of 760 nm line centre frequency is used and the scanned-wavelength direct absorption spectroscopy method and wavelength modulation spectroscopy method are applied to measure absorption signals below 793 K temperature region. The experimental results show that oxygen concentration are measured within 1% accuracy and temperature are measured within 5% accuracy. This new method of simultaneous measurements of concentration and temperature with a single diode laser shows a great promise.
Stability of Attached Flame in
/CO Syngas Non-premixed Turbulent Jet Flame
Hwang, Jeong-Jae ; Bouvet, Nicolas ; Sohn, Ki-Tae ; Yoon, Young-Bin ;
Journal of the Korean Society of Combustion, volume 17, issue 1, 2012, Pages 22~29
The detachment stability characteristics of syngas
/CO jet attached flames were studied. The flame stability was observed while varying the syngas fuel composition, coaxial nozzle diameter and fuel nozzle rim thickness. The detachment stability limit of the syngas single jet flame was found to decrease with increasing mole fraction of carbon monoxide in the fuel. In hydrogen jet flames with coaxial air, the flame detachment stability was found to be independent of the coaxial nozzle diameter. However, velocities of appearance of liftoff and blowout velocities of lifted flames have dependence. At lower fuel velocity range, the critical coaxial air velocity leading to flame detachment increases with increasing fuel jet velocity, whereas at higher fuel velocity range, it decreases. This increasing-decreasing non-monotonic trend appears for all
/CO syngas compositions (50/50~100/0%
/CO). To qualitatively understand the flame behavior near the nozzle rim,
chemiluminescence imaging was performed near the detachment limit conditions. For all fuel compositions, local extinction on the rim is observed at lower fuel velocities(increasing stability region), while local flame extinction downstream of the rim is observed at higher fuel velocities(decreasing stability region). Maximum values of the non-monotonic trends appear to be identical when the fuel jet velocity is normalized by the critical fuel velocity obtained in the single jet cases.
Characteristics of High-Frequency Combustion Instabilities Occurring in Combustion Devices
Seo, Seong-Hyeon ;
Journal of the Korean Society of Combustion, volume 17, issue 1, 2012, Pages 30~36
Dynamic characteristics of combustion occurring in various combustion devices have been extensively studied since most of high-performance combustion devices are susceptible to hazardous, unstable combustion that deteriorates combustor's lifetime. One of the most severe unstable combustion phenomena is high-frequency combustion instability in which heat release fluctuations from combustion are coupled to resonant modes of the combustor. Here in this study, characteristics of high-frequency combustion instabilities observed in three different combustion devices have been presented. Lean-premixed combustion instability occurs mainly due to equivalence ratio fluctuations which induce large heat release oscillations at lean conditions. Liquid-fueled combustion also shows high-frequency instability from energy coupling between pressure and heat release oscillations.
A Comparative Study Between Diffusive-thermal and Buoyancy-driven Self-excitations in Laminar Free Jet Flames with Applied DC Electric Fields
Han, Jong-Kyu ; Yoon, Sung-Hwan ; Park, Jeong ; Kwon, Oh-Boong ; Kim, Tae-Hyung ; Park, Jong-Ho ;
Journal of the Korean Society of Combustion, volume 17, issue 1, 2012, Pages 37~47
Experimental study on comparison of diffusive-thermal self-excitation with buoyancy-driven one due to accumulation of partially premixed, preheated mixture in front of edge flame was conducted in horizontally and vertically injected laminar free-jet flames with an applied DC electric field of -10 kV. The application of horizontal injection method with the DC electric field to jet flames was experimentally designed to suppress heat-loss-induced self-excitation and thereby to highlight the definite difference between both diffusive-thermal and buoyancy-driven self-excitations with the same order of O(1.0 Hz), in that diffusive-thermal self-excitation has not been so far found experimentally in laminar jet flames. Flame stability maps in vertically and horizontally injected jet flames are presented. The distinct modes of individual self-excitation are shown to be well described by their own phase diagrams. The results show that buoyancy-driven self-excitation due to the accumulation of partially premixed, preheated mixtures in front of edge flame is branched from the buoyancy-induced self-excitation with O(10 Hz) due to a flame flicker. Once the buoyancy-driven self-excitation appears, it suppresses buoyancy-induced as well as diffusive-thermal self-excitation. The key characteristics for individual self-excitation are discussed and their functional dependencies of Strouhal number upon related physical parameters are also presented.
Effect of Coflow Air Velocity on Heat-loss-induced Self-excitation in Laminar Lifted Propane Coflow-Jet Flames Diluted with Nitrogen
Lee, Won-June ; Yoon, Sung-Hwan ; Park, Jeong ; Kwon, Oh-Boong ; Park, Jong-Ho ; Kim, Tae-Hyung ;
Journal of the Korean Society of Combustion, volume 17, issue 1, 2012, Pages 48~57
Laminar lifted propane coflow-jet flames diluted with nitrogen were experimentally investigated to determine heat-loss-related self-excitation regimes in the flame stability map and elucidate the individual flame characteristics. There exists a critical lift-off height over which flame-stabilizing effect becomes minor, thereby causing a normal heat-loss-induced self-excitation with O(0.01 Hz). Air-coflowing can suppress the normal heat-loss-induced self-excitation through increase of a Peclet number; meanwhile it can enhance the normal heat-lossinduced self-excitation through reducing fuel concentration gradient and thereby decreasing the reaction rate of trailing diffusion flame. Below the critical lift-off height. the effect of flame stabilization is superior, leading to a coflow-modulated heat-loss-induced self-excitation with O(0.001 Hz). Over the critical lift-off height, the effect of reducing fuel concentration gradient is pronounced, so that the normal heat-loss-induced self-excitation is restored. A newly found prompt self-excitation, observed prior to a heat-loss-induced flame blowout, is discussed. Heat-loss-related self-excitations, obtained laminar lifted propane coflow-jet flames diluted with nitrogen, were characterized by the functional dependency of Strouhal number on related parameters. The critical lift-off height was also reasonably characterized by Peclet number and fuel mole fraction.
The Influence of Magnetic Field on Diffusion Flames: Role of Magnetic Field On/Off Frequency and Duty Ratio
Lee, Won-Nam ; Bae, Seung-Man ;
Journal of the Korean Society of Combustion, volume 17, issue 1, 2012, Pages 58~65
The influence of magnetic field on propane and acetylene diffusion flames have been experimentally investigated using an electromagnetic system. Periodically induced magnetic field having various frequencies and duty ratios was established in square wave form. The maximum intensity and gradient of magnetic field were 1.3 T and 0.27 T/mm, respectively. The width of a propane flame was reduced up to 4.5% and the brightness was enhanced up to 25% when the magnetic field was induced. The soot emission from an acetylene flame was ceased when magnetic field was induced. The alteration of flow field, which is due to the paramagnetic characteristics of oxygen molecule, is most likely to be responsible for the change in flame size and brightness. The effect of magnetic field on diffusion flames, which competes with the gravitational effect, was more apparent from a smaller size flame. The magnetic field effect, therefore, could be important under microgravity conditions. Since the time required to alter the flow field must be finite, the magnetic field effect is likely to be less significant for a periodically oscillating magnetic field at a high frequency or having a small duty ratio.