• Journal of the Korean Society of Safety
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• v.24 no.5
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• pp.28-33
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• 2009

The thermochemical parameters for safe handling, storage, transport, operation and process design of flammable substances are explosion limit, flash point, autoignition temperatures(AITs), minimum oxygen concentration(MOC), heat of combustion etc.. Also it is necessary to know explosion limit at high temperature and pressure. For the safe handling of benzene, lower explosion limit(LEL) at $25^{\circ}C$, the temperature dependence of the explosion limits and flash point were investigated. And the AITs for benzene were experimented. By using the literatures data, the lower and upper explosion limits of benzene recommended 1.3 vol% and 8.0 vol%, respectively. This study measured relationship between the AITs and the ignition delay times by using ASTM E659-78 apparatus for benzene, and the experimental AIT of benzene was $583^{\circ}C$. The new equations for predicting the temperature dependence of the explosion limits of benzene is proposed. The values calculated by the proposed equations were a good agreement with the literature data.

• Fire Science and Engineering
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• v.33 no.5
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• pp.1-6
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• 2019

The recent development of biofuel production technology facilitates the widespread use of bioethanol and biodiesel by mixing them with fossil fuels. However, the use of these new blended fuels in combustion could result in severe safety problems, such as fire and explosion. In this study, numerical simulation was performed on the well-stirred reactor (WSR) to simulate the autoignition temperature (AIT) in homogeneous combustion and clarify the effect of ethanol addition on the AIT, the most important property for assessing the potential for fire and explosion. Response surface methodology (RSM) was introduced as a design of experiment (DOE), enabling the AIT to be predicted and optimized systematically with respect to three independent variables: ethanol mole fraction, equivalence ratio, and pressure. The results show that the autoignition temperature primarily depends on the ethanol mole fraction and pressure, while the effects of the equivalence ratio are independent of the AIT. RSM accurately predicted the experimental AIT, indicating that this method can be used to effectively predict the key properties involved in fires and explosions.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.1
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• pp.75-81
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• 2012

Autoignited lifted flames in laminar jets with hydrogen-enriched methane fuels have been investigated experimentally in heated coflow air. The results showed that the autoignited lifted flame of the methane/hydrogen mixture, which had an initial temperature over 920 K, the threshold temperature for autoignition in methane jets, exhibited features typical of either a tribrachial edge or mild combustion depending on fuel mole fraction and the liftoff height increased with jet velocity. The liftoff height in the hydrogen-assisted autoignition regime was dependent on the square of the adiabatic ignition delay time for the addition of small amounts of hydrogen, as was the case for pure methane jets. When the initial temperature was below 920 K, where the methane fuel did not show autoignition behavior, the flame was autoignited by the addition of hydrogen, which is an ignition improver. The liftoff height demonstrated a unique feature in that it decreased nonlinearly as the jet velocity increased. The differential diffusion of hydrogen is expected to play a crucial role in the decrease in the liftoff height with increasing jet velocity.

• Journal of the Society of Disaster Information
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• v.19 no.2
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• pp.292-304
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• 2023

Purpose: This study was conducted to obtain experimental data for the establishment of preventive measures against fire, as large and small fire accidents occur at production and storage sites of superabsorbent polymers developed for the convenience of daily life. Method: The sample container was fixed at 0.2m in both length and width, and was shaped into a rectangular cuboid with heights of 3cm, 5cm, 7cm, and 14cm to access an infinite flat plane. The sample container was fixed in the center of a thermostatic bath that was heated to a predetermined temperature according to a preset temperature control program. If the central temperature of the sample rose more than 20℃ above the set temperature, it was determined to have 'ignited', and if it remained similar to the set temperature, it was determined to have 'unignited'. Result: The critical autoignition temperature was calculated to be 212.5℃ for a sample container with a height of 3cm, 202.5℃ for 5cm, 192.5℃ for 7cm, and 177.5℃ for 14cm. The ignition induction time to reach the highest temperature was approximately 42hours for 3cm, 91hours for 5cm, 151hours for 7cm, and 300hours for 14cm. Conclusion:① As the size of the sample container increased, the autoignition temperature decreased and the ignition induction time to reach the highest temperature increased. ② The apparent activation energy was calculated to be 39.30kcal/mol, with a correlation of 99.5%.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.6
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• pp.778-787
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• 1999

In this study, the autoignition process of liquid fuel, injected into hot and stagnant air in a 2-D axisymmetric confined cylindrical combustor, has been investigated. Eulerian-Lagrangian scheme was adopted to analyze the two-phase flow and combustion. The unsteady conservation equations were used to solve the transition of the gas field. Interactions between two phases were accounted by using the particle source in cell (PSI-Cell) model, which was used for detailed consideration of the finite rates of transports between phases. And infinite conduction model was adopted for the vaporization of droplets. The results have shown that the process of the autoignition consists of heating up of droplets, vaporization, mixing and ignition. The ignition criteria could be determined by the temporal variations of temperature, reaction rate and species mass fraction. And the effects of various parameters on ignition phenomena are examined. These have shown that the increasing the reaction rate and/or the vaporization rate can reduce the ignition delay time.

• Journal of the Society of Disaster Information
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• v.19 no.2
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• pp.280-291
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• 2023

Purpose: As fire accidents happen at the production and storage sites of superabsorbent polymers for convenience of daily life, an experimental study was conducted to secure basic data to establish practical preventive measures against them. Method: The sample container (20cm width × 20cm length) was made into a rectangular cuboid with the heights of 3cm, 5cm, 7cm, and 14cm, respectively, to allow access to the infinite flat plane. The front and back of the container were covered with a 300-mesh stainless steel mesh for one-dimensional heat transfer. The sample container was placed in the center of the thermostatic bath, which was heated to a predetermined temperature by setting the thermostat program in advance, and it was determined to be 'ignited' when the central temperature of the sample rose by more than 20℃ above the set temperature, and "unignited" when it was maintained at an approximate value of the set temperature. Result: The critical autoignition temperature was calculated to be 217.5℃ when the height of the sample container was 3 cm, 212.5℃ when it was 5 cm, 202.5℃ when it was 7cm, and 187.5℃ when it was 14cm. The ignition induction time to reach the maximum temperature was 34hours for 3cm, 76hours for 5cm, 143hours for 7cm, and 318hours for 14cm. Conclusion: ① As the size of the container increased, the autoignition temperature decreased and the induction time to reach the maximum temperature increased. ② An apparent activation energy was calculated to be 44.92kcal/mol, with a correlation of 96.93%.

• Fire Science and Engineering
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• v.25 no.2
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• pp.120-125
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• 2011

For the safe handling of n-dodecane, the explosion limits were investigated and the lower flash points and AITs (autoignition temperatures) by ignition delay time were experimented. By using the literatures data, the lower and upper explosion limits of n-dodecanee recommended 0.6 Vol.% and 4.7 Vol.%, respectively. The lower flash points of n-dodecane by using closed-cup tester were experimented $77^{\circ}$ and $80^{\circ}C$. The lower flash points of n-dodecane by using open cup tester were experimented $84^{\circ}C$ and $87^{\circ}C$. This study measured relationship between the AITs and the ignition delay times by using ASTM E659-78 apparatus for n-dodecane. The experimental AIT of n-dodecane was $222^{\circ}C$.

• Journal of the Korean Society of Combustion
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• v.16 no.2
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• pp.16-22
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• 2011

It is a challenging task to apply large detailed chemical mechanisms of fuel oxidation in simulation of complex combustion phenomena. There exist a few systematic methodologies to reduce detailed chemical mechanisms to smaller sizes involving less computational load. This research work concerns generation of a skeletal chemical mechanism by a directed relation graph with specified accuracy requirement. Two sequential stages for mechanism reduction are followed in a perfectly stirred reactor(PSR) for high temperature chemistry and to consider the autoignition delay time for low and high temperature chemistry. Reduction was performed for the detailed chemical mechanism of n-heptane consisting of 561 species and 2539 elementary reaction steps. Validation results show acceptable agreement for the autoignition delay time and the PSR calculation in wide parametric ranges of pressure, temperature and equivalence ratio.

• Journal of the Korean Institute of Gas
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• v.10 no.2 s.31
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• pp.33-39
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• 2006

For the safety design and operation of many gas process, it is necessary to know certain explosion limit, flash point, auto ignition temperature and minimum oxygen concentration of handling substances. Also it is necessary to know explosion limit at high temperature and pressure. For the safe handling of propane, explosion limit and autoignition temperature of combustion characteristics for propane were investigated. By using the literatures data, the lower and upper explosion limits of propane recommended 2.0 vol% and 10.0 vol%, respectively. Also autoignition temperatures of propane with ignition sources recommended $450^{\circ}C$ at the electrically heated cruicible fumace(the whole surface heating) and recommended about $960^{\circ}C$ at the local hot surface. The new equations for predicting the temperature and the pressure dependence of the explosion limits of propane are proposed. The values calculated by the proposed equations were a good agreement with the literature data.

• Journal of the Korean Institute of Gas
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• v.19 no.5
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• pp.54-60
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• 2015

The autoignition temperature (AIT) of a material is the lowest temperature at which the material will spontaneously ignite. The AIT is important index for the safe handling of flammable liquids which constitute the solvent mixtures. This study measured the AITs of n-decane+ethylbenzene system by using ASTM E659 apparatus. The AITs of n-decane and ethylbenzene which constituted binary system were $210^{\circ}C$ and $430^{\circ}C$, respectively. The experimental AITs of n-decane+ethylbenzene mixture were a good agreement with the calculated AITs by the proposed equations with about $11^{\circ}C$ A.A.D.(average absolute deviation).