• Title/Summary/Keyword: fire fuel

Search Result 426, Processing Time 0.029 seconds

Analysis of Forest Fire Spread Rate and Fire Intensity by a Wind Model (모형실험에 의한 풍속변화에 따른 산불의 확산속도와 강도 분석)

  • 채희문;이찬용
    • Korean Journal of Agricultural and Forest Meteorology
    • /
    • v.5 no.4
    • /
    • pp.213-217
    • /
    • 2003
  • Forest fire spread and intensity were modeled as a function of wind and fuel. Spread rate and intensity of forest fire were related to weight and thickness of forest fuel beds and to wind speed. Forest fire spread rate and fire intensity were differentiated according to wind speed. Rapid wind speed causes a faster forest fire spread rate and greater fire intensity than does slow wind speed. Relative burning time of the fire from beginning to end in the model was 161 sec at a wind speed of 0.5 m/sec and 146 sec at 1m/sec on the model. Average forest lire spread rate was 0.014 m/sec at a wind speed of 0.5 m/sec and 0.020 m/sec at 1m/sec. Average fire intensity was 0.183 ㎾/m at a wind speed of 0.5 m/sec, 0.259 ㎾/m at 1m/sec. Fire intensity was greater when forest fire spread rate was rapid.

Fire Safety evaluation of High Pressure Hydrogen System for FCEV (연료전지차량용 고압수소저장시스템의 화재 안전성 평가)

  • Choi, Young-Min;Jang, Gyu-Jin;Kim, Sang-Hyun;Hang, Ki-Ho;Hang, In-Cheol;Ahn, Byung-Ki;Lim, Tae-Won
    • Transactions of the Korean hydrogen and new energy society
    • /
    • v.20 no.3
    • /
    • pp.188-193
    • /
    • 2009
  • Fuel cell vehicles are equipped with Pressure Relief Devices(PRDs) installed in pressure tank cylinder to prevent the explosion of the tank during a fire. PRDs are safety devices that perceive a fire and release gas in the pressure tank cylinder before it is exploded. But if the PRD does not actuate, because either the PRD fails or can't be surrounded by the flame of a fire, the tank will rupture and produce a blast wave and hydrogen fire ball. In this paper, we observed the fire behavior of actual fuel cell vehicle, comparing with that of gasoline vehicle.

Extinguishment of Liquid Fuel Fire by Water Mist Containing Additives

  • Park, Jae-Man;Won, Jung-Il;Shin, Chang-Sub
    • International Journal of Safety
    • /
    • v.4 no.2
    • /
    • pp.24-29
    • /
    • 2005
  • An experimental study was presented for extinguishing characteristics of liquid fuel fire by water mist($Dv_{0.99}{\leq}200{\mu}m$) containing potassium acetate and sodium acetate trihydrate. To evaluate the extinguishing performance of water mist containing additives, the evaporation characteristics of a water droplet on a heated surface was examined. The evaporation process was recorded by a charge-coupled-device camera. Also, small-scale extinguishing tests were conducted for n-heptane pool fire in ventilated space. During the experiments, flame temperatures were measured, and concentrations of oxygen and carbon monoxide were analyzed by a combustion gas analyzer. The average evaporation rate of water droplet containing additives was lower than that of pure water at a given surface temperature and decreased with the concentration increase due to the precipitation of salt in the liquid-film and change of surface tension. In case of using additives, the fire extinguishing times was shorter than that of pure water at a given discharge pressure and it was because the momentum of a water droplet containing additives was increased. And also dissociated metal atoms, potassium or sodium, were reacted as a scavenger of the major radical species OH, H which were generated for combustion process. Moreover, at a high pressure of 4 MPa, the fire was extinguished through blowing effect as well as primary extinguishing mechanisms.

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
    • /
    • v.17 no.1
    • /
    • pp.1-12
    • /
    • 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.

An Experimental Study of Smoke Movement of the Various Fire Location in Room (실내공간에서 화재 발생위치에 따른 연기거동에 대한 실험연구)

  • Yu, Hong-Seon;Jeong, Jin-Yong;Lee, Jae-Ha;Hong, Gi-Bae
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.26 no.5
    • /
    • pp.703-709
    • /
    • 2002
  • In order to investigate the smoke movement in three dimensional room fires, the center fire, wall fire and corner fire plume in different sized fires were studied experimentally by rectangular pool fire using methanol as a fuel. As the fire size became larger for the center fires placed at the center of the floor, the air flow rate entrained through the opening, average hot layer temperature, flame angle deflected backwards and mean flame height was observed to increase. On the other hand, as the fire size became smaller, the neutral plane height in the door and time reached steady-state was observed to decrease. The average hot layer temperature, mean flame height and doorway neutral plane height obtained from comer fire were higher than those produced by wall fires and center fires. The simple model for describing the effect of walls on the mean flame height was presented. It was shown that the model provides a good description of the present measurements, when used with the assumption by Hansell(1993), that the increase of the average flame height is equal to the ratio of the open to the total perimeters of the trays. Also the two models for predicting the effects of walls on the mean flame height were presented. These models overestimated the measured values of the mean flame height above fuel trays close to a wall and in a corner by approximately 19-26%, respectively.

Sensitivity analysis of input variables to establish fire damage thresholds for redundant electrical panels

  • Kim, Byeongjun;Lee, Jaiho;Shin, Weon Gyu
    • Nuclear Engineering and Technology
    • /
    • v.54 no.1
    • /
    • pp.84-96
    • /
    • 2022
  • In the worst case, a temporary ignition source (also known as transient combustibles) between two electrical panels can damage both panels. Mitigation strategies for electrical panel fires were previously developed using fire modeling and risk analysis. However, since they do not comply with deterministic fire protection requirements, it is necessary to analyze the boundary values at which combustibles may damage targets depending on various factors. In the present study, a sensitivity analysis of input variables related to the damage threshold of two electrical panels was performed for dimensionless geometry using a Fire Dynamics Simulator (FDS). A new methodology using a damage evaluation map was developed to assess the damage of the electrical panel. The input variables were the distance between the electrical panels, the vertical height of the fuel, the size of the fire, the wind speed and the wind direction. The heat flux was determined to increase as the vertical distance between the fuel and the panel decreased, and the largest heat flux was predicted when the vertical separation distance divided by one half flame length was 0.3-0.5. As the distance between the panels increases, the heat flux decreases according to the power law, and damage can be avoided when the distance between the fuel and the panel is twice the length of the panel. When the wind direction is east and south, to avoid damage to the electrical panel the distance must be increased by 1.5 times compared to no wind. The present scale model can be applied to any configuration where combustibles are located between two electrical panels, and can provide useful guidance for the design of redundant electrical panels.

Combustion Characteristics of Ionized Fuels for Battery System Safety (배터리 시스템 안전을 위한 이온화 연료의 연소 특성)

  • Ko, Hyeok Ju;Lee, Eui Ju
    • Journal of the Korean Society of Safety
    • /
    • v.33 no.1
    • /
    • pp.22-27
    • /
    • 2018
  • Many electronic devices are powered by various rechargeable batteries such as lithium-ion recently, and occasionally the batteries undergo thermal runaway and cause fire, explosion, and other hazards. If a battery fire should occur in an electronic device of vehicle and aircraft cabin, it is important to quickly extinguish the fire and cool the batteries to minimize safety risks. Attempts to minimize these risks have been carried out by many researchers but the results have been still unsatisfied. Because most rechargeable batteries are operated on the ion state during charge and discharge of electricity and the combustion of ion state has big difference with normal combustion. Here we focused on the effect of ions including an electron during combustion process. The effects of an ionized fuel on the flame stability and the combustion products were experimentally investigated in the propane jet diffusion flames. The burner used in this experiment consisted of 7.5 mm diameter tube for fuel and the propane was ionized with th ionizer (SUNJE, SPN-11). The results show that toe overall flame stability and shape such as flame length has no significant difference even in the higher ion concentration. However the fuel ionization affects to the pollutant emissions such as NOx and soot. NOx and CO emissions measured in post flame region decreased by fuel ionization, especially high fuel velocity, i.e. high ion density. TGA analysis and morphology of soot by TEM indicates that the fuel ionization makes soot to be matured.

Emission Characteristics of Gasoline/ethanol Mixed Fuels for Vehicle Fire Safety Design (차량화재 안전설계를 위한 휘발유/에탄올 혼합연료의 연소생성물 배출 특성)

  • Kim, Shin Woo;Lee, Eui Ju
    • Journal of the Korean Society of Safety
    • /
    • v.34 no.1
    • /
    • pp.27-33
    • /
    • 2019
  • Combustion characteristics of gasoline/ethanol fuel were investigated both numerically and experimentally for vehicle fire safety. The numerical simulation was performed on the well-stirred reactor (WSR) to simulate the homogeneous gasoline engine and to clarify the effect of ethanol addition in the gasoline fuel. The simulating cases with three independent variables, i.e. ethanol mole fraction, equivalence ratio and residence time, were designed to predict and optimized systematically based on the response surface method (RSM). The results of stoichiometric gasoline surrogate show that the auto-ignition temperature increases but NOx yields decrease with increasing ethanol mole fraction. This implies that the bioethanol added gasoline is an eco-friendly fuel on engine running condition. However, unburned hydrocarbon is increased dramatically with increasing ethanol content, which results from the incomplete combustion and hence need to adjust combustion itself rather than an after-treatment system. For more tangible understanding of gasoline/ethanol fuel on pollutant emissions, experimental measurements of combustion products were performed in gasoline/ethanol pool fires in the cup burner. The results show that soot yield by gravimetric sampling was decreased dramatically as ethanol was added, but NOx emission was almost comparable regardless of ethanol mole fraction. For soot morphology by TEM sampling, the incipient soot such as a liquid like PAHs was observed clearly on the soot of higher ethanol containing gasoline, and the soot might be matured under the undiluted gasoline fuel.

On the Fire Behavior Due to the Ventilation Condition in the Fire Compartment (환기 조건에 따른 화재거동 연구)

  • Kim, Sung-Chan;Hamins, Anthony
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.32 no.5
    • /
    • pp.367-373
    • /
    • 2008
  • A series of fire experiments has been conducted to provide an improved understanding of the fire structure of under-ventilated compartment fires. A comprehensive and quantitative assessment of gaseous species from the fire was made in the upper layer of fire in a 40 % reduced scale ISO 9705 fire compartment. The global equivalence ratio (GER) concept was used to characterize the fire behavior for various fire sizes, fuel types and ventilation conditions. The oxygen concentration in the upper layer reached to zero near the global equivalence ratio of $0.4{\sim}0.6$ while the carbon monoxide concentration increases with increasing the global equivalence ratio. Classification parameters of ISO19706 were also compared with the reduced scale experimental data for under ventilation fire.

Estimation of Canopy Fuel Characteristics for Pinus densiflora Stands Using Diameter Distribution Models: Forest Managed Stands and Unmanaged Stands (직경분포모형을 이용한 소나무림의 수관연료특성 예측: 산림시업지 임분과 비시업지 임분에서)

  • Lee, Sun Joo;Kim, Sung Yong;Lee, Byung Doo;Lee, Young Jin
    • Journal of Korean Society of Forest Science
    • /
    • v.107 no.4
    • /
    • pp.412-421
    • /
    • 2018
  • The objective of this study was to analyze the effects of forest management activities on canopy fuel characteristics for Pinus densiflora stands in South Korea. We used 1,085 managed stands data and 349 unmanaged stands data of the National Forest Inventory for this study, and it was estimated by using the Weibull function for the growth of stand and canopy fuel characteristics. Comparing the canopy fuel characteristics for the managed stands and unmanaged stands shows that the average canopy fuel load is about 14% higher than that of managed stands, and the canopy bulk density is also approximately 16% higher. The results of comparing growth projections for 40 years, 50 years and 60 years with the Weibull function are as follows: Over time, managed stands was predicted the maximum number of medium and large class diameter, while unmanaged stands was predicted maximum number of small and medium class diameter. From a fire fuel perspective, unmanaged stands are predicted to be of the type small class diameter and high density, which is a good condition for crown fire. In addition, Canopy fuel load, Canopy bulk density is relatively higher than managed stands, indicating that the possibility of high crown fire hazard.