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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
Editor in Chief :
Volume & Issues
Volume 4, Issue 2 - Dec 1999
Volume 4, Issue 1 - Jul 1999
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Analysis of Group Ignition of Pulverized Coal Particles
Suh, K.K. ; Kim, H.Y. ;
Journal of the Korean Society of Combustion, volume 4, issue 2, 1999, Pages 1~10
Pulverized coal is widely used as the source of electrical power generation and industrial processes. Numerical analysis on the transient ignition process of the cloud of pulverized coal particles in various cases is carried out. Particle radius, initial particle temperature, number density are chosen as major parameters that influence the characteristics of ignition and combustion. The result can be summarized as follow. The ignition occurs at the position that is closed to the surface of the cloud. Maximum temperature and velocity appear at ignition point, and the concentrations of gaseous fuel and oxidizer decrease rapidly near the ignition point. The chemical reaction takes place in wider zone as number density and particle radius decrease. The ignition delay is shortest when particle radius is about
, and tends to be shorter as number density and initial ambient temperature increase.
Combustion Characteristics of Wood Materials (1) (Mass Reduction and Ignition Delay)
Kim, Chun-Jung ;
Journal of the Korean Society of Combustion, volume 4, issue 2, 1999, Pages 11~22
Combustion characteristics of the wood chips(balsa chips) were experimentally investigated with respect to the thermal recycle system of the urban waste. The urban waste contains plastics, vegetable and wood materials. Wood was chosen as an example of the one of the component of urban dust. A small wood chip was burned in a electric furnace by the micro-electric balance. The mass reduction rate was normalized by the initial mass of test piece and the time of volatile combustion end. When the mass of the wood chips(balsa chips) was larger than 0.5g, the combustion similarity was found on the normalized mass reduction rate.
Experimental Study on Turbulent Ethylene Diffusion Flame
Yang, G.S. ; Kim, Y.M. ;
Journal of the Korean Society of Combustion, volume 4, issue 2, 1999, Pages 23~33
A turbulent non-premixed ethylene flame, which was set up in a vertical wind tunnel, was examined to understand the effect of turbulent mixing on formations of soot and gaseous species in the flames. Temperature and velocity profiles were measured using uncoated thermocouples and LDV system. Gaseous samples were withdrawn by using a water cooled stainless iso-kinetic gas sampling probe. The samples for inorganic compounds and light hydrocarbons were collected with sampling bottles and were analyzed by a gas chromatography. The samples for aromatic hydrocarbons were collected on a sorbent tube and were analyzed on a GC/MS system. Some of main results were followed. CO and
were measured relatively in early part of flame and the concentration of CO was greater than that of
all over the early flame region due to the scavenging of the oxidizing species OH by soot particles. Aromatic hydrocarbons were measured at x/D=122 along the radial direction and main important species were benzene, xylene, toluene, styrene, indene, naphthalene. The peak points of these compounds occurred at r/D=0.8 apart from the center of flame, around in which the concentration of
decayed relatively rapidly from the maximum value.
A Study on the Flame Structure and NOx Distribution In Coaxial Diffusion Combustor
Kim, K.S. ; Lee, W.S. ; Kang, I.G. ; Lee, D.H. ;
Journal of the Korean Society of Combustion, volume 4, issue 2, 1999, Pages 35~41
The purpose of this study is to establish the flame structure and NOx emission characteristics of the swirl flow coaxial diffusion combustion in the model gas turbine combustor. The mean temperature, ion currents and NOx emission measurement technique showed the effect of equivalence ratio into flame length and flame stability. As a result of this study, NOx emission was increased by increasing the equivalence ratio, and the peak value of the NOx was appeared near the flame front.
Liquid LPG Spray Characteristics With Injection Pressure Variation -Comparison with Diesel Spray-
Lim, Hee-Sung ; Park, Kweon-Ha ;
Journal of the Korean Society of Combustion, volume 4, issue 2, 1999, Pages 43~50
Liquefied petroleum gas (LPG) has been used as motor fuel due to its low emissions and low cost. The fuel feeding system has been improved with stringent requirement for exhaust emissions. LPG carburetion system was first introduced, then the system has been changed to a precisely controlled gas injection system, but this gas feeding system has a limitation on improving power output. In order to improve an engine performance, a multi-point port injection system was introduced recently, and a liquid direct injection system into a cylinder was suggested as a next generation system to maximize a fuel economy as well as a power. This study addresses the analysis of the LPG spray from diesel injectors. The spray images are visualized and compared with diesel sprays in a wide injection pressure range. The photographs show much wider dispersion of LPG sprays.
Laminar Flamelet Modeling of Combustion Processes and NO Formation in Nonpremixed Turbulent Jet Flames
Kim, Seong-Ku ; Kim, Hoo-Joong ; Kim, Yong-Mo ;
Journal of the Korean Society of Combustion, volume 4, issue 2, 1999, Pages 51~62
NOx formation in turbulent flames is strongly coupled with temperature, superequilibrium concentration of O radical, and residence time. This implies that in order to accurately predict NO level, it is necessary to develop sophisticated models able to account for the complex turbulent combustion processes including turbulence/chemistry interaction and radiative heat transfer. The present study numerically investigates the turbulent nonpremixed hydrogen jet flames using the laminar flamelet model. Flamelet library is constructed by solving the modified Peters equations and the turbulent combustion model is extended to nonadiabatic flame by introducing the enthalpy defect. The effects of turbulent fluctuation are taken into account by the presumed joint PDFs for mixture fraction, scalar dissipation rate, and enthalpy defect. The predictive capability of the present model has been validated against the detailed experimental data. Effects of nonequilibrium chemistry and radiative heat loss on the thermal NO formation are discussed in detail.
Effects of EGR and Premixedness on NO Formation of Methane/Air Flames
Lee, Won-Nam ; Lee, Woong-Jae ;
Journal of the Korean Society of Combustion, volume 4, issue 2, 1999, Pages 63~74
The effects of EGR and premixedness on NO formation have been numerically investigated. The flame structure is classified into three categories; premixed flame(
, rich/lean premixed flame(
and 0.8) and diffusion flame(
). NO formation/destruction mechanisms are assorted to thermal, reburn and Fenimore mechanisms. The temperature of unburned gas is arranged to 298 and 500 K to have access to the condition in a real internal combustion engine. The results show that all three NO formation/destruction reaction rates in the fuel rich flame zone could be decreased by EGR for rich/lean premixed flames, while those in the fuel lean flame zone are not significantly changed. Near the stagnation plane, however, only the thermal NO reaction rate is decreased. The contribution of reburn and Fenimore mechanisms for the net NO production becomes less significant as the premixedness of a flame increases. The larger amount of NO reduction with EGR is expected under the higher temperature and/or higher fuel/air premixedness conditions due to the increased contribution of the thermal mechanism. The role of Fenimore and reburn mechanisms could be important for rich premixed and diffusion flames; therefore, the effect of EGR on NO reduction could vary with fuel/air premixedness. The premixedness of a partially premixed flame changes the flame structure and could affect the NO production characteristics.
Temperature Measurement in Concentric Diffusion Flames by Rapid Insertion Technique
Lee, Gyo-Woo ; Chung, Young-Rok ; Jurng, Jong-Soo ;
Journal of the Korean Society of Combustion, volume 4, issue 2, 1999, Pages 75~83
The effect of temperature distributions on soot volume fraction in double-concentric diffusion flames have been investigated experimentally. Using fine thermocouple wires and a rapid insertion mechanism, we have measured temperature without the effect of soot particles attached to the thermocouple junction, which can lower the temperature signal about 100 K by increasing the heat loss from the junction by radiation. The temperature at the flame axis is higher in the double-concentric diffusion flames than in normal co-flow diffusion flames because of the inverse diffusion flame. However, it is almost the same as that at the periphery of normal flames, on which the inverse flame does not have an effect. Thus, the lower soot concentration found in the double-concentric diffusion flame can be explained by the effect of nitrogen diffusion from the central air jet.
Studies on Coal Combustion Characteristics and NOx Emission and Reduction in the Drop Tube Furnace
Han, Woong ; Park, Chu-Sik ; Choi, Sang-Il ; Lee, Ik-Hyung ; Yang, Hyun-Soo ;
Journal of the Korean Society of Combustion, volume 4, issue 2, 1999, Pages 85~95
The objective of this study was to obtain basic data for the staged combustion toward the NOx reduction in coal combustion. Combustion and NOx emission/reduction were investigated by using DTF. NOx emission was decreased with decreasing air ratio and with increasing volatile content in coal. In particular, effective NOx reduction was achieved at high temperature at the onset of combustion with fuel rich condition.
Addition on Flame Structure and NOx Formation of
Counterflow Diffusion Flames
Lee, S.R. ; Han, J.W. ; Lee, C.E. ;
Journal of the Korean Society of Combustion, volume 4, issue 2, 1999, Pages 97~108
This numerical study was to investigate the effect of
addition on the structures and NOx formation characteristics in
counterflow diffusion flame. The importance of radiation effect was identified and
addition effect was investigated in terms of thermal and chemical reaction effect. Also the causes of NOx reduction were clarified by separation method of each formation mechanisms. The results were as follows : The radiation effect was intensified by
addition. Thermal effect mainly contributed to the changes in flame structure and the amount of NO formation but the chemical reaction effect also cannot be neglected. The reduction of thermal NO was dominant with respect to reduction rate, but that of prompt NO was dominant with respect to total amount.