• Journal of the Korean Society of Safety
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• 제21권3호
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• pp.45-52
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• 2006

The AITs(autoignition temperatures) describe the minimum temperature to which a substance must be heated, without the application of a flame or spark, which will cause that substance to ignite. The AITs are often used as a factor in determining the upper temperature limit for processing operations and conditions for handling, storage and transportation, and in determining potential fire hazard from accidental contact with hot surfaces. The measurement AITs are dependent upon many factors, namely initial temperature, pressure, volume, fuel/air stoichiometry, catalyst material, concentration of vapor, time lag. Therefore, the AITs reported by different ignition conditions are sometimes significantly different. This study measured the AITs of benzene, toluene and xylene isomers from time lag using AS1M E659-78 apparatus. The experimental ignition delay times were a good agreement with the calculated ignition delay times by the proposed equations wtih a few A.A.D.(average absolute deviation). Also The experimental AITs of benzene, toluene, o-xylene, m-xylene and p-xylene were $583^{\circ}C,\;547^{\circ}C,\;480^{\circ}C,\;587^{\circ}C,\;and\;557^{\circ}C$, respectively.

• Fire Science and Engineering
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• 제18권3호
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• pp.30-38
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• 2004

An important characteristics during fire growth is the phenomena of flashover, which is the transition from the local combustion to the full-room fire. The aim of this study is to predict the flashover times, the ignition times and HRR(heat release rate) of flashover for building interior materials. By using the literature data and RSM(response surface methodology), the new equations for predicting the flashover time, the ignition time and the HRR of building interior materials are proposed. The A.A.P.E.(average absolute percent error) and the A.A.D.(average absolute deviation) of the reported and the calculated flashover times were 38.74sec and 51.24sec respectively, and the correlation coefficient was 0.975. The A.A.P.E and the A.A.D of the reported and the calculated ignition times were 10.96sec and 1.97sec, and the correlation coefficient was 0.962. Also the A.A.P.E and the A.A.D. of the reported and the calculated the HRR of flashover by means of times were 29.92 and 514, and the correlation coefficient was 0.830. The values calculated by the proposed equations were in good agreement with the literature data. Therefore, it is expected that this proposed equations will support the use of the research for other building interior materials.

• Transactions of the Korean Society of Mechanical Engineers B
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• 제39권12호
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• pp.945-952
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• 2015

The autoignition characteristics of biosyngas were investigated both numerically and experimentally. The effects of the temperature, gas composition, and pressure on the autoignition characteristics were evaluated. A shock tube was employed to measure the ignition delay times of the biosyngas. The numerical study on the ignition delay time was performed using the CHEMKIN-PRO software to validate the experimental results and predict the chemical species in the combustion process. The results revealed that the ignition delay time increased with an increase in the hydrogen fraction in the mixture. Under most temperature conditions, the ignition delay time decreased with a pressure increase. However, the ignition delay time increased with an increase in pressure under relatively low temperature conditions.

• Journal of Hydrogen and New Energy
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• 제24권6호
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• pp.573-579
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• 2013

Hydrogen engine with homogeneous charged compression ignition can achieve high efficiency by high compression ratio and rapid chemical reaction rates spatially. However, it needs to expansion of the operation range with over-all load conditions which is very narrow due to extremely high pressure rise rate. The adoption of the lean boosting in a HCCI $H_2$ engine is expected to be effective in expansion of operation range since minimum compression ratio for spontaneous ignition is decreased by low temperature combustion and increased surround in-cylinder pressure. In order to grasp its possibility by using lean boosting in the HCCI $H_2$ engine, compression ratio required for spontaneous ignition, expansion degree of the operation range and over-all engine performance are experimentally analyzed with the boosting pressure and supply energy. As the results, it is found that minimum compression ratio for spontaneous ignition is down to the compression ratio(${\varepsilon}$=19) of conventional diesel engine due to decreased self-ignition temperature, and operation range is extended to 170% in term of the equivalence ratio and 12 times in term of the supply energy than that of naturally aspirated type. Though indicated thermal efficiency is decreased by reduced compression ratio, it is over at least 46%.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2015년도 제51회 KOSCO SYMPOSIUM 초록집
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• pp.177-180
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• 2015

The chemical aspects of primary reference fuel (PRF)/air mixture under RCCI conditions are investigated to provide fundamental insights into the ignition characteristics of RCCI combustion. Chemical explosive mode analysis (CEMA) is adopted to understand the ignition process of the lean PRF/air mixture by identifying controlling species and elementary reactions at different locations and times.

• Fire Science and Engineering
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• 제21권3호
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• pp.41-46
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• 2007

The combustion characteristics of surface forest fire fuels was analysed using variable external irradiation level. The characteristics such as ignition time, ignition temperature, critical heat flux and mass loss rate were measured. Fuel samples were exposed to incident heat fluxes from 8 to $50\;kW/m^2$. For the measurement of various combustion characteristics, the size of specimen holder was $100\;mm{\times}100\;mm{\times}12\;mm$ and the fuel samples grinded by electric mill were the fallen leaves of Quercus variabilis and Pinus densiflora. As results, the occurrence of ignition is possible to the heat flux more than $9\;kW/m^2$. The fuel of Pinus densiflora keeps its high temperature longer than that of Quercus variabilis during the combustion process. The results of measurement shows that the maximun and average mass loss rate of Quercus variabilis larger than that of Pinus densiflora.

• Fire Science and Engineering
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• 제21권4호
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• pp.25-31
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• 2007

The combustion characteristics and combustion heat of sandwich panel cores were analysed using variable external irradiation level. The characteristics such as ignition time, critical heat flux, ignition temperature and surface temperature profile were measured. Fuel samples were exposed to incident heat fluxes from 15 to $50\;kW/m^2$. For the measurement of various combustion characteristics, the size of specimen was $100\;mm\;{\times}\;100\;mm\;{\times}\;50\;mm$ and the samples were 3 different kinds. As results, Type B showed the best characteristics in measurement of combustion heat and ignition temperature and Type C showd the best characteristics in critical heat flux and surface temperature profile than that of the other two. In conclusion, we knew that Type C had the best performance in fire safety from all data of this study.

• Journal of the Korean Chemical Society
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• 제43권2호
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• pp.156-160
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• 1999

The ignition of methane-oxygen mixtures highly diluted with argon was examined in the temperature range of 1516-1937 K behind a reflected shock wave. The ignition delay times were measured by monitoring pressure profiles and the total emissions at 5.0 cm from the end wall. It was found that the experimental result was correlated by the temperature and the concentrations of the gases. To complement the experiment, computer modeling study of methane oxidation was carried out using a GRI 1.2 mechanism.

• Journal of the Korean Society of Combustion
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• 제4권1호
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• pp.17-26
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• 1999

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.

• Journal of the Korean Society of Safety
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• 제30권2호
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• pp.21-26
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• 2015

For the safe handling of o-cresol, this study was investigated the explosion limits of o-cresol in the reference data. The flash points and AITs(auto-ignition temperatures) by ignition delay time were experimented. The lower flash points of o-cresol by using closed-cup tester were experimented in $77^{\circ}C$ and $80^{\circ}C$. The lower flash points of o-cresol by using open cup tester were experimented in $86^{\circ}C$ and $87^{\circ}C$. This study measured relationship between the AITs and the ignition delay times by using ASTM E659 tester for o-cresol. The AIT of o-cresol was experimented as $495^{\circ}C$. The lower explosion limit(LEL) by the measured the lower flash point for o-cresol was calculated as 1.27 Vol%.