• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.3
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• pp.13-19
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• 2003

Mathematically simplified reaction scheme that simulates autoignitions of the end gases in spark ignition engines has been studied computationally. The five equation model is described, to predict the essential features of hydrocarbon oxidation. This scheme has been calibrated against autoignition delay times measured in rapid compression machines. The rate constants, activation temperatures, Ta, Arrhenius preexponential constants, A, and heats of reaction for stoichiometric n-heptane/air, iso-octane/air, and their mixtures have all been optimised. The optimisation has been guided by Morley's correlation of the ratio of chain branching to linear termination rates with octane number. Comparisons between computed and experimental autoignition delay times have validated the Present simplified reaction scheme and the influences of octane number upon autoignition delay times have been computationally investigated. It has been found that both cool flame and high temperature direct reactions can have an effect on autoignition delay times.

• 한국연소학회:학술대회논문집
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• 2012.11a
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• pp.305-307
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• 2012

This study was computationally explored how the fuel autoignition reactivity was affected by operating parameters such as fuel, pressure, intake temperatures, engine speed and EGR compositions for HCCI combustion. This is done for DME and CHEMKIN-PRO was used as a solver. At first, influence of the operating parameters and EGR compositions were showed. And then, in order to clarify the mechanism of them on autoignition reactivity, data-sets of kinetic were analyzed to investigate the elementary reaction path for heat release at transient tempeatures by using contribution matrix.

• Fire Science and Engineering
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• v.24 no.2
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• pp.172-177
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• 2010

The values of the AIT (autoignition temperature) for fire and explosion protection are normally the lowest reported. The MAITB (Minimum Autoignition Temperature Behavior) of flammable liquid mixture is exhibited when the AITs of mixture is below the AIT of the individual components. The MAITB is an interesting experimental features, which can be significant from the perspective of industrial fire safety. In this study, the AITs of toluene + iso-propanol(IPA) and p-xylene + n-butanol systems were measured using ASTM E659-78 apparatus. The AITs of toluene, iso-propanol (IPA), pxylene and n-butanol which constituted two binary systems were $547^{\circ}C,\;463^{\circ}C,\;557^{\circ}C$ and $340^{\circ}C$ respectively. The toluene + iso-propanol(IPA) system is exhibited MAITB at 0.3 mole fraction of toluene, and its minimum autoignition temperature was $460^{\circ}C$.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.1
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• pp.76-83
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• 2002

Mathematically and chemically simplified reaction scheme for n(heptane that simulates autoignitions of the end gases in spark ignition engines has been developed and studied computationally. The five(equation model is described, to predict the essential features of hydrocarbon oxidation. This scheme has been calibrated against autoignition delay times measured in rapid compression machines. The rate constants, activation temperatures, Ta, Arrhenius pre-exponential constants, A, and heats of reaction for stoichiometric nheptane/air has all been optimized. Comparisons between computed and experimental autoignition delay times have validated the present simplified reaction scheme. The influences of heat loss and concentration of chain carrier at the beginning of compression upon autoignition delay times have been computationally investigated.

• Journal of ILASS-Korea
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• v.23 no.2
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• pp.90-95
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• 2018

The goal of this study is to experimentally observe the autoignition phenomena of a diesel/1-butanol mixture droplet in ambient pressure and $700^{\circ}C$ condition. A volume ratio of 1-butanol in the fuel was set to 25, 50 and 75%. A single droplet was installed at the tip of fine thermocouple, and the electric furnace dropped down to make elevated temperature condition. Droplet behavior during the experiment could be divided into 3 stages including droplet heating, puffing and autoignition/combustion. Puffing process intensively observed for the case of 1-butanol volume ratio of 25 and 50%, but did not occur at 75%. Increase of 1-butanol volume ratio hindered rise of the droplet temperature and delayed ignition. In addition, puffing process also affected on autoignition, so the ignition delay of 1-butanol volume ratio of 50% was became longer than that of 75% case.

• Fire Science and Engineering
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• v.28 no.4
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• pp.44-49
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• 2014

The autoignition temperaturs (AIT) of solvent mixture is important index for the safe handling of flammable liquids which constitute the solvent mixtures. This study measured the AIT and ignition delay time for Propionic acid and 3-Hexanone system by using ASTM E659 apparatus. The AITs of Propionic acid and 3-Hexanone which constituted binary system were $511^{\circ}C$ and $425^{\circ}C$, respectively. The experimental AIT of Propionic acid and 3-Hexanone system were a good agreement with the calculated AIT by the proposed equations with a few average absolute deviation (A.A.D.). And Propionic acid and 3-Hexanone system was shown the minimum autoignition temperature behavior (MAITB).

• Journal of the Korean Society of Safety
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• v.23 no.6
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• pp.70-75
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• 2008

The values of the AIT(Autoignition temperature) for fire and explosion protection are normally the lowest reported. The minimum autoignition temperature behavior(MAITB) of flammable liquid mixtures is exhibited when the AIT of mixture is below the AIT of the individual components. The MAITB is an interesting experimental features, which can be significant from the perspective of industrial safety. In this study, the AITs of m-xylene+n-butyric acid and ethylbenzene+n-butanol systems were measured using ASTM E659-78 apparatus. The AITs of m-xylene, n-butyric acid, ethylbenzene and n-butanol which constituted two binary systems were $587^{\circ}C$, $510^{\circ}C$, $475^{\circ}C$ and $340^{\circ}C$ respectively. The m-xylene+n-butyric acid system is exhibited MAITB at 0.3 mole fraction of m-xylene, and its minimum autoignition temperature was $460^{\circ}C$.

• Journal of Mechanical Science and Technology
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• v.16 no.8
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• pp.1127-1134
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• 2002

The effects of pressure and temperature on the autoignition of propane and n-butane blends were investigated using a rapid compression machine (RCM) , which is widely used to examine the autoignition characteristics. The RCM was designed to be capable of varying the compression ratio between 5 and 20 and minimize the vortex formation on the cylinder wall using a wedge-shaped crevice. The initial temperature and pressure of the compressed gas were varied in range of 720∼900 K and 1.6∼ 1.8 MPa, respectively, by adjusting the ratio of the specific heat of the mixture by altering the ratio of the non-reactive components (N$_2$, Ar) under a constant effective equivalence ratio (ø$\_$f/= 1.0) The gas temperature after the compression stroke could be obtained from the measured time-pressure record. The results showed a two-stage ignition delay and a Negative Temperature Coefficient (NTC) behavior which were the unique characteristic of the alkane series fuels. As the propane concentration in the blend were increased from 20% and 40% propane, the autoignition delay time increased by approximately 41 % and 55% at 750 K. Numerical reduced kinetic modeling was performed using the Shell model, which introduced some important chemical ideas, represented by the generic species. Several rate coefficients were calibrated based on the experimental results to establish an autoignition model of the propane and n-butane blends. These coefficients can be used to predict the autoignition characteristics in LPG fueled Sl engines.

• Journal of the Korean Society of Safety
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• v.5 no.2
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• pp.17-23
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• 1990

This study was performed by experiments with ASTM's apparatus for determination of autoignition temperature to obtain autoignition characteristics of 1-Heptene, 2-Heptene and 3-Heptene, respectively. As results, minimum autoignition temperatures (MAIT) of 1-Heptene, 2-Heptene and 3-Heptene were 246$^{\circ}C$, 248$^{\circ}C$ and 254$^{\circ}C$, respectively and each dropping volume of these temperatures was 0.25$m\ell$, 0.20$m\ell$ and 0.20$m\ell$. Instantaneous ignition temperatures measured at each dropping volume of Heptene were 371$^{\circ}C$, 357$^{\circ}C$ and 342$^{\circ}C$, respectively. Relation ignition delay time with ignition temperature at minimum autoignition temperature agreed well with Semenov's equation, and the values of apparent activation energy from this equation were 47Kca1/mo1 for 1-Heptene, 35Kca1/mo1 for 2-Heptene and 29Kca1/mo1 for 3-Heptene. It was found that the values of apparent activation energy decreased as the position of double bond changed from end to center in C-C chain.

• Journal of the Korean Society of Safety
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• v.32 no.2
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• pp.66-71
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• 2017

The autoignition temperature (AIT) is crucial combustible characteristics which need attention in chemical process that handle hazardous materials. The AIT, also to as minimum spontaneous ignition temperature(MSIT), is the lowest temperature of a hot surface at which the substance will spontaneously ignite without any obvious sources of ignition such as a spark or flame. The AIT may be used as combustion property to specify operating, storage, and materials handling procedures for process safety. This study measured the AITs of n-propanol+acetic acid system from ignition delay time(time lag) by using ASTM E659 apparatus. The AITs of n-propanol and acetic acid which constituted binary system were $435^{\circ}C$ and $212^{\circ}C$, respectively. The experimental AITs of n-propanol+acetic acid system were a good agreement with the calculated AITs by the proposed equations with a few A.A.D.(average absolute deviation). In the case of n-propanol and acetic acid system, the minimum autoignition temperature behavior (MAITB), which is lower than the lower AIT, is shown among the two pure substances constituting the mixture.