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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Society of Combustion
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Journal DOI :
The Korean Society of Combustion
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Volume & Issues
Volume 4, Issue 2 - Dec 1999
Volume 4, Issue 1 - Jul 1999
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Parametric Sensitivity of the Flow Characteristics on Pulverized Coal Gasification
Cho, Han-Chang ; Shin, Hyun-Dong ;
Journal of the Korean Society of Combustion, volume 4, issue 1, 1999, Pages 1~15
In order to analyze the sensitivity on the pulverized coal flames of the several variables, a numerical study was conducted at the gasification process. Eulerian approach is used for the gas phase, whereas lagrangian approach is used for the solid phase. Turbulence is modeled using the standard
model. The turbulent combustion incorporates eddy dissipation model. The radiation was solved using a Monte-Carlo method. One-step two-reaction model was employed for the devolatilization of Kideco coal. In pulverized flame of long liftoff height, the initial turbulent intensity seriously affects the position of flame front. The radiation heat transfer and wall heat loss ratio distort the temperature distributions along the reactor wall, but do not influence the reactor performance such as coal conversion, residence time and flame front position. The primary/secondary momentum ratio affects the position of flame front, but the coal burnout is only slightly influenced. The momentum ratio is a variable only associated with the flame stabilization such as flame front position. The addition of steam in the reactor has a detrimental effect on all the aspects, particularly reactor temperature and coal burnout.
A Numerical Study on Interaction and Combustion of Droplets Injected into a Combustor
Kook, J.J. ; Park, S.H. ;
Journal of the Korean Society of Combustion, volume 4, issue 1, 1999, Pages 17~26
Vaporization, ignition and combustion of fuel droplets in tandem array are theoretically investigated to understand the droplet interactions in combustors. Including the effects of density variation in gas-phase, internal circulation and transient liquid heating, a numerical studies are performed by changing parameters such as initial droplet temperatures, initial droplet spacings, initial Reynolds numbers, surrounding gas temperatures, and activation energies of fuel vapors. Combustion regime maps classify the droplet combustion phenomena according to the configuration and location of the flame with respect to injection Reynolds numbers and surrounding gas temperatures. In addition, it is shown that the dynamic histories of droplets and ignition delay times are dependent on droplet size ratios and initial spacings of tandem droplets.
Study on the Measurement of Emission Spectrum and Reaction Mechanism of OH Radical in the Nitrogen Corona Discharge System for Removal of
in Flue Gas
Park, Chul-Woung ; Hahn, Jae-Won ; Shin, Dong-Nam ;
Journal of the Korean Society of Combustion, volume 4, issue 1, 1999, Pages 27~38
We constructed a wire-cylinder type pulsed corona discharge system for
removal, which was operated in room temperature. A emission spectrometer was built with a boxcar averager and monochrometer equipped with photo-multiplier tube detector. The sensitivity of the emission spectrometer was greatly improved by synchronizing the emission spectrometer with pulsed corona discharge system using a triggered spark-gap switch.
) was measured in the range of 300 - 450 nm and oxidizing OH radical emission(
) was measured in case
was supplied with water bubbling. As wet gas composition of inlet
supplied in the discharge system increased, the intensity of OH emission was increased and saturated at wet gas composition 50%. We also investigated additive effect of
on the intensity of OR emission and
reduction and analysed the related reaction mechanism in corona discharge process.
additive increased the intensity of OH emission and
A Study on Combustion Visualizations and Radical Characteristics using Optically Accesible Engine
Choi, Su-Jin ; Chang, Young-June ; Jeon, Chung-Hwan ;
Journal of the Korean Society of Combustion, volume 4, issue 1, 1999, Pages 39~47
A combustion flame visualization system, which is used as an engine diagnostics tool, was developed in order to understand the combustion reaction mechanism in the development stage for S.I. engines. The measurement system consists of an I-CCD camera and a computer-aided image processing system. By using optically accessible engine system, the flame structure was analyzed from the acquired graylevel image and the direction of flame propagation (shape of flame) has been measured to understand combustion phenomena. And combustion radical which involves combustion information were measured. As a result, strong relation between combustion radicals intensity ratio and air excess ratio was found.
Measurement of soot concentration in flames using laser-induced incandescence method
Jurng, Jong-Soo ; Lee, Gyo-Woo ;
Journal of the Korean Society of Combustion, volume 4, issue 1, 1999, Pages 49~57
An experimental study on double-concentric diffusion flame has been carried out in order to investigate the shape, the flame length, and the other characteristics of the flame. Flow visualization of the flame by the
particles and also the emission measurements are conducted. The commercial grade LP gases are used as fuel. The inverse diffusion flames are formed at the center when the central air flow rate is about 0.1 L/min. With a larger flow rate of the central air jet than 0.2 L/min the flame turns to be an annular-shaped flame, which is very bright. When the central air flow rate increases over 2.4 L/min, the flame turns to blue and the flame tips are opened because of the lifting of the inner part of the flame. Because of this lifting and the incomplete combustion, the CO emission increases abruptly from 25 ppm to more than 150 ppm. On the contrary, the NOx emission is decreased.
Shock Tube and Modeling Study of the Formation and the Reduction of Nitrogen Oxides; Ammonia Oxidation
Shin, Kuan-Soo ; Cho, Hye-Yun ; Shim, Seung-Bo ; Jee, Sung-Bae ;
Journal of the Korean Society of Combustion, volume 4, issue 1, 1999, Pages 59~65
mixtures have been studied behind reflected shock waves over the temperature range of 1600-2300 K and the pressures in the range of 1.1-1.6 atm. The pressure profile and the radiation emitted behind the shock waves have been monitored to give empirical correlations between ignition delay times and the mixture concentrations with the experimental conditions. On the basis of this data, several kinetic mechanisms proposed for ammonia oxidation at high temperatures have been tested. The ignition delay times obtained from the mechanism proposed by Miller and Smook were in good agreement with our experimental results.
A Study on Low Emission Pulverized Coal Combustion in the 2 Staged Coaxial Cyclone Combustor
Choi, Sang-Il ; Park, Chu-Sik ; Kim, Sung-One ; Kim, Ho-Young ;
Journal of the Korean Society of Combustion, volume 4, issue 1, 1999, Pages 67~83
The objective of this study is development of low emission pulverized coal combustor for reducing pollutant emission generated from coal combustion. Low emission combustion technology for reducing NOx and fly ash was investigated by using 2 stage coaxial cyclone combustor. Staged combustion was employed for NOx reduction and high temperature slagging combustion was also studied for fly ash removal in the combustor. The result of this study shows that the low emission combustion system can reduce the amount of atmospheric pollutions with improved boiler efficiency and performance.
Experimental Study on Combustion Characteristics of Porous Ceramic Liquid Fuel Combustor
Chung, K.H. ; Lim, I.G. ;
Journal of the Korean Society of Combustion, volume 4, issue 1, 1999, Pages 85~93
Experimental study on a porous ceramic liquid fuel combustor is performed. Compact burner with low pollutant emission and high combustion efficiency is realized through the use of porous ceramic materials of high porosities. The use of porous ceramic materials in burner material results in rapid vaporization of liquid fuel and enhancement in mixing process, and thus nearly premixed combustion of liquid fuel is achieved instead of diffusion and partially premixed combustion method, which is often used and apt to produce high pollutant emissions such as CO, NOx and soot. With this enhanced vaporization and premixing method of liquid fuel vapor and air, it is found that enhanced combustion process with intense radiation output and better emission characteristics in NOx, CO and soot emission, compared to other conventional liquid fuel burning method, are possible.
Combustion Characteristics of A Regenerative Combustor with the Change of Alternating Period
Yang, B.O. ; Lim, I.G. ;
Journal of the Korean Society of Combustion, volume 4, issue 1, 1999, Pages 95~103
Experimental study on combustion characteristics of a regenerative combustor has performed. High-temperature air combustion in the regenerative combustor is obtained through heat recovery from exhaust gas flow by porous ceramic materials and through alternation of air flow direction through the combustor. Temperature field, CO and NOx emission with respect to the frequency of alternation are measured. It is found that at initial stage of the alternation, temperature of inlet section of main combustion chamber is increased sharply since both high temperature air preheated by the ceramics and prompt fuel injection results in rapid combustion. Following this initial stage, combustion temperature is reduced as the preheated air temperature is reduced. However peak temperature in the chamber and exhaust gas temperature are decreased as the alternation period is reduced, increased temperature of ceramic is observed. CO and NOx emission with respect to the alternation period is also examined. It is found that there exists a range of optimum alternating period for CO and NOx emission characteristics.
Tomographic Reconstruction of a Non-axisymmetric Diffusion Flame
Yang, In-Young ; Ha, Kwang-Soon ; Choi, Sang-Min ;
Journal of the Korean Society of Combustion, volume 4, issue 1, 1999, Pages 105~115
The structure of a non-axisymmetric propane diffusion flame was investigated. Tomographic reconstruction method to convert the line-integrated self-emission data of a fuel-rich diffusion flame with square cross-section was applied to get the spatially reconstructed emission data. Modified Shepp-Logan filter and concentric squares raster were chosen for reconstructing arbitrarily shaped object in this process. Spatially reconstructed emission data were then interpreted to several physical quantities, such as flame edge, FWHM, perimeter and 3-D flame temperature distribution. Necessary assumptions were discussed and the results were interpreted. In comparison with axisymmetric flame, flame edge was developed higher, and sooting region of upstream was broader than in this non-axisymmetric one. At some height, the flame was shrunk very rapidly and finally formed circular cross-section.
Mixing Augmentation of Transverse Injection of Fuel in SCRamjet Engine
Kim, Young-Jin ; Lee, Sang-Hyeon ;
Journal of the Korean Society of Combustion, volume 4, issue 1, 1999, Pages 117~129
A method for the mixing augmentation of the transverse injection of fuel in a Scramjet combustor is suggested. Based on the fact that the main factor controlling the mixing characteristics in transverse injection is the effective back-pressure (the pressure around the injection hole) it is tried to make a flow expansion near the injection port in order to reduce effective back-pressure. A three dimensional Navier-Stokes code adopting the upwind method of Roe#s flux difference splitting scheme is used. The k-w SST turbulence model turbulence model is used to calculate the turbulent viscosity. It is shown that the reducing of the effective back-pressure make it possible to increase the penetration distance and to increase the mixing rate without excessive losses of stagnation pressure. Also, it is shown that the streamwise vorticity generated by baroclinic torque has great influences on the mixing process.
Numerical Prediction of NOx in the Nonpremixed Hydrogen-Air Flame using the Quasi-Laminar Reaction Modelling
Kim, Seong-Lyong ; Jeung, In-Seuck ; Yoon, Young-Bin ;
Journal of the Korean Society of Combustion, volume 4, issue 1, 1999, Pages 131~139
A Numerical Analysis of NOx production in Hydrogen-Air flame is performed using the quasi-laminar reaction modelling. As results, in low global strain rate region,
, the quasi-laminar reaction modelling reproduces the experimentally observed EINOx half power scaling that the ratio of EINOx and flame residence time,
, is proportional to the square root of global strain rate. Thus, it suggests that turbulence-chemistry interaction has a minor impact on the trend of NOx production in low global strain rate region. However, the quasi-laminar reaction modelling predicts the higher temperature and NOx than experimentally observed. This overprediction may be due to the lack of radiation and quasi-laminar reaction modelling.
Numerical Analysis for the Performance Prediction of Combustion Chamber of Commercial Incinerator
Lee, Jin-Wook ; Park, Byung-Soo ; Yun, Yong-Seung ; Seo, Jung-Dae ; Huh, Il-Sang ;
Journal of the Korean Society of Combustion, volume 4, issue 1, 1999, Pages 141~153
Numerical analysis for the combustion flow in the combustion chamber of incineration system has been carried out in order to acquire the basic design capability of incineration system. Established mathematical model was applied to the performance prediction of the pre-designed combustion chamber of commercial plant. Especially, combustion characteristics and the variation of flow pattern have been deeply discussed in accordance with secondary air injection. Secondary air injection was effective for the turbulent mixing between air and carbon monoxide/volatile matter resulting in considerably reduced CO content at the exit. Secondary air injection was found to be one of the key design parameters because the size of recirculation zone could be changed with the variation of injection characteristics.