• 제목/요약/키워드: Flame Propagation Rate

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A study on the bed combustion of solid waste (고형 폐기물층 연소에 관한 연구)

  • Sin, Dong-Hun;Choe, Sang-Min
    • 한국연소학회:학술대회논문집
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    • 1998.10a
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    • pp.1-8
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    • 1998
  • Waste combustion above a grate is the core process of incineration systems, stability of which should be guaranteed for emission minimization. However, complicated reactions and heat and mass transfer phenomena make understanding the process difficult. One dimensional bed combustor with a numerical combustion model is utilized to investigate the combustion process of the bed, using cubic wood particles as a simulated fuel. Bed combustion behavior is characterized with apparent flame propagation speed, which has close relationship with air supply rate and chemical and physical characteristics of the fuel. Base on the availability of oxygen, two distinct reaction zone is identified; the oxygen-limited and the reaction-limited zone leading to the extinction by excessive convection cooling. The numerical modeling shows good agreement with the experimental results. The transient bed combustion behavior of local temperature and oxygen consumption rate is adequately reproduced. The numerical model is extended to model the waste bed combustion of a commercial incineration plant, which shows meaningful results as well.

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Investigation of Solid Fuel Combustion Characteristics in Various Types of Combustors (다양한 종류의 연소로 내 고체 연료의 연소 특성 고찰)

  • Choi, Jin-Hwan;Yang, Won;Lee, Sang-Deuk;Choi, Sang-Min
    • Journal of the Korean Society of Combustion
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    • v.9 no.3
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    • pp.1-9
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    • 2004
  • This study is aimed to characterize the combustion behavior of solid fuel in the various types of the combustors: stoker, rotary kiln and fluidized bed type combustors. Three different types of reduced-scale combustors are introduced, and temperatures and flue gas compositions are measured for various fuel sizes, water contents, initial temperature, and air flow rates. In case of the rotary kiln combustor, effects of rotating speed of the combustor are also investigated. Mean carbon conversion time (MCCT) and flame propagation rate (FPR) are used for the quantitative analysis. It is revealed that the reaction rates of the fuel are significantly influenced by the fuel characteristics, type of the combustors and air flow rate. Major design parameters for each type of the combustors are summarized through the reduced-scaled model analysis.

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Combustion Characteristics of Landfill Gas in Constant Volume Combustion Chamber for Large Displacement Volume Engine (II) - Combustion Analysis - (대형기관 모사 정적연소실에서 매립지 가스의 연소특성에 대한 연구 (II) - 연소 분석 -)

  • Kwon, Soon Tae;Park, Chanjun;Ohm, Inyong
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.37 no.8
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    • pp.743-752
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    • 2013
  • This is the second paper on the combustion characteristics of landfill gas in a constant volume combustion chamber for a large displacement volume commercial engine, and it discusses the combustion process on the basis of pressure measurements. The results show that the bimodal peak pressure phenomenon, which is caused by the interaction of the heat release and the heat transfer, is more apparent as the mixtures are more favorable to combustion, and the magnitudes of the pressures depend on the unburned fraction. In addition, there exist four main inflection points during heat release owing to variations in the heat transfer area related to flame propagation from the ignition point. Furthermore, the number of inflection points increases as the mixture quality worsens because of the extended burn duration. Consequently, the sophisticated interactions between the heat transfer area changing pattern due to flame propagation and transfer duration might cause very peculiar heat release patterns.

Laminar Burning Velocities of Atmospheric Coal Air Mixtures

  • Park, Ho Young;Park, Yoon Hwa
    • KEPCO Journal on Electric Power and Energy
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    • v.2 no.1
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    • pp.89-96
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    • 2016
  • The mechanism for laminar dust flame propagation can only be elucidated from a comprehensive mathematical model which incorporates conduction and radiation, as well as the chemical kinetics of particle devolatilization and gas phase and char reaction. The mathematical model for a flat, laminar, premixed coal-air flame is applied to the atmospheric coal-air mixtures studied by Smoot and co-workers, and comparisons are made with their measurements and predictions. Here the principal parameter for comparison is the laminar burning velocity. The studies of Smoot and co-workers are first reviewed and compared with those predicted by the present model. The effects of inlet temperature and devolatilization rate constants on the burning velocities are studied with the present model, and compared with their measurements and predictions. Their measured burning velocities are approximately predicted with the present model at relatively high coal concentrations, with a somewhat increased inlet temperature. From the comparisons, their model might over-estimate particle temperature and rates of devolatilization. This would enable coal-air mixtures to be burned without any form of preheat and would tend to increase their computed values of burning velocity.

THERMAL AND SMOKE MEASUREMENTS OF VEHICLE FIRES Establishing practical large-scale experiment for vehicle fires

  • Kim, Jeong-Hun;Kim, Hong;Lee, Bog-Young;Lee, Chang-Seop
    • Proceedings of the Korea Institute of Fire Science and Engineering Conference
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    • 1997.11a
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    • pp.335-342
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    • 1997
  • Experiments were conducted to evaluate the hazard risks of vehicle fires. Sensors were strategically placed in passenger cars to determine the temperature, propagation rate and direction of flame. The life safety hazard evaluations such as smoke and gas analysis were included. An important ignition position was performed in the engine compartment. The effects of different ignition positions and the opening of door glasses were also reviewed. The experimental results indicate that the maximum temperature when a vehicle burns varies commonly from 90$0^{\circ}C$ -100$0^{\circ}C$. The flame reaches in the face of a driver about 6-7minutes and the windshield glass breaks about 10 minutes after the ignition in the engine compartment of vehicle. And the smoke and gas concentrations reached the limit of human inhalation after 13-14 minutes. Especially the concentrations of carbon monoxide exceeded the TWA(50 ppm) during short time after ignition in cases of all experiments.

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A Study on the Burning Characteristics of Interior Boards and Louvers (내장용 판재 및 루버의 연소발열특성 연구)

  • Nam, Dong-Gun;Kim, Sung-Chan
    • Fire Science and Engineering
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    • v.28 no.2
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    • pp.34-39
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    • 2014
  • It is necessary to enhance its availability and reliability of performance based fire design of building with various type of database such as experiments, survey and fire properties and so on. In order to utilize to the performance based fire design, the present study has been performed a series of experiments to investigate the burning characteristics of building materials for two types of interior board and three types of interior louver. The burning test has been also conducted for different thickness because it may show different characteristics of burning behavior such as flame spread rate and flame propagation time. The result shows that the effective heat release per unit mass of interior materials were almost constant with 15.3~16.9 MJ/kg regardless of its thickness while the peak heat release rate and maximum $CO_2$ concentration was varied with thickness.

Development of Crown Fire Propagation Probability Equation Using Logistic Regression Model (로지스틱 회귀모형을 이용한 수관화확산확률식의 개발)

  • Ryu, Gye-Sun;Lee, Byung-Doo;Won, Myoung-Soo;Kim, Kyong-Ha
    • Journal of the Korean Association of Geographic Information Studies
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    • v.17 no.1
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    • pp.1-12
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    • 2014
  • Crown fire, the main propagation type of large forest fire, has caused extreme damage with the fast spread rate and the high flame intensity. In this paper, we developed the probability equation to predict the crown fires using the spatial features of topography, fuel and weather in damaged area by crown fire. Eighteen variables were collected and then classified by burn severity utilizing geographic information system and remote sensing. Crown fire ratio and logistic regression model were used to select related variables and to estimate the weights for the classes of each variables. As a results, elevation, forest type, elevation relief ratio, folded aspect, plan curvature and solar insolation were related to the crown fire propagation. The crown fire propagation probability equation may can be applied to the priority setting of fuel treatment and suppression resources allocation for forest fire.

A Study on the Transition of Hydrogen-Air and LPG-Air Explosion to Fire (수소와 액화석유 가스의 공기혼합기의 폭발 후 화재로 전이 연구)

  • Oh Kyu-Hyung;Lee Sung-Eun;Rhie Kwang-Won
    • Journal of the Korean Society of Safety
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    • v.19 no.4 s.68
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    • pp.150-154
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    • 2004
  • Gas explosion characteristics of hydrogen and liquefied petroleum gas(LPG) were measured in 6L cylindrical vessel, and experiment for explosion to fire transition phenomena of the gases were carried out using the 270L vessel. Explosion characteristics were measured using the stain type pressure transducer and explosion to fire transition phenomena was analyzed with the hish-speed camera. Base on the experiment, it was found that explosion pressure was most high slightly above the stoichiometric concentration, and explosion pressure rise rate and flame propagation velocity were proportional to the combustion velocity. And we find that those kind of explosion characteristics affect the explosion-to-fire transition, in addition, explosion flame temperature, flame residence time, are important parameters in explosion-to-fire transition.

Parametric Study on Combustion Characteristics of CNG Fuel (연소실 매개변수에 따른 천연가스 연소 특성)

  • Lee, Seang-Wock;Song, Young-Mo;Baik, Doo-Sung
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.32 no.7
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    • pp.513-517
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    • 2008
  • A parametric study was made to understand the fundamentals of combustion of CNG fuel in a constant volume chamber in the respect of swirl effect, and the numbers of spark ignition. Optical devices were applied for the visualization of the physics of combustion, and combustion pressures and exhaust emission were measured at several equivalence ratios by controlling speeds of a swirling motor. When the speed of a swirling motor was raised the combustion conditions were improved. The corresponding maximum combustion pressure and heat release rate were increased and the speed of flame propagation was getting faster. This research may contribute to improve the performance of CNG engine and reduce emissions in future.

Numerical Analysis for Autoignition Characteristics of Turbulent Gaseous Jets in a High Pressure Environment (고압 분위기하에 분사된 메탄가스 제트의 자연발화 및 화염전파 특성 해석)

  • Kim, Seong-Ku;Yu, Yong-Wook;Kim, Yong-Mo
    • 한국연소학회:학술대회논문집
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    • 2002.06a
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    • pp.24-32
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    • 2002
  • The autoignition and subsequent flame propagation of initially nonpremixed turbulent system have been numerically analyzed. The unsteady flamelet modeling based on the RIF (Representative Interactive Flamelet) concept has been employed to account for the influences of turbulence on these essentially transient combustion processes. In this RIF approach, the partially premixed burning, diffusive combustion and formation of pollutants(NOx, soot) can be consistently modeled by utilizing the comprehensive chemical mechanism. To treat the spatially distributed inhomogeneity of scalar dissipation rate, the multiple RIFs are employed in the framework of EPFM(Eulerian Particle Flamelet Model) approach. Computations are made for the various initial conditions of pressure, temperature, and fuel composition. The present turbulent combustion model reasonably well predicts the essential features of autoignition process in the transient gaseous fuel jets injected into high pressure and temperature environment.

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