• 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 the Korean Society of Combustion
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• v.17 no.2
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• pp.9-16
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• 2012

Iso-octane, n-heptane and their blends were tested in a constant volume combustion chamber to measure laminar flame speeds. The experimental apparatus was automatically controlled to enhance the accuracy and data acquisition speed. A large database of laminar flame speeds at elevated temperatures and pressures was established. From this database, laminar flame speeds of iso-octane, n-heptane and their blends were investigated and analysed to derive new correlation to predict laminar flame speeds at any blending ratio. The new flame speed model was successfully applied to these fuels with limited range of errors.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2012.04a
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• pp.258-261
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• 2012

풀화재에서 화염화염진동은 주위공기와의 밀도차에 의한 부력효과에 기인하여 주로 발생한다. 본 연구는 풀화재의 화염불안정성에 대해 산화제 유속 및 농도 변화에 따른 효과를 검토하기 위하여 컵버너 실험을 수행하였다. 실험결과는 산화제의 농도를 변화시켰을 경우에는 산화제의 불활성기체의 농도가 증가할수록 청염의 길이가 길어지고 컵버너 끝단으로부터 부상되는 것이 관찰된다. 한편, 산화제의 유속이 증가함에 따른 진동주파수가 감소함을 보인다. 이는 무차원 변수로 표현되는 주파수와 부력의 관계로 도시하였을 때 다양한 속도스케일을 사용할 수 있었지만, 연료와 산화제의 유속차로 정의되는 특성속도인 경우에 정지되어 있는 공기중에서의 풀화재 진동과 일치하는 관계식을 얻을 수 있었다. 그리고 진동주파수는 산화제 희석율과는 특정한 관계를 보이지 않는데 이는 국부적 화염구조와 연관성을 가지기 때문으로 판단된다.

• Journal of the Korean Society of Safety
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• v.27 no.3
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• pp.71-76
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• 2012

The coflow velocity effect on the minimum extinguishing concentration(MEC) was investigated experimentally in heptane cup-burner flames. Various inert gases($N_2$, Ar, $CO_2$, He) were added into the oxidizer to find the critical concentration and the effectiveness of the agents on flame extinction. The experimental results showed that the MECs were increased with increasing coflow velocity for most inert gases except helium, but the higher coflow velocity induced the lower burning rates of heptane. This indicated that the increase of coflow velocity resulted in the decrease of fuel velocity evaporated from fuel surface, and hence the stain rate on the reaction zone was also decreased. In the case of helium as a additive, the extinguishing concentration was independent of the coflow velocity because the heat conductivity was ten times larger than the other inert gases and flow effect by a strain rate might be compensated for heat loss to the surroundings.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.05a
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• pp.383-389
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• 2010

The vapor concentration of hexane in a liquid spray jet in crossflow was qualitatively measured on the basis of the infrared (IR) extinction techniques. The objectives of the present study are to understand the whole evaporation process from droplet breakup to vapor and to confirm the usefulness of IR emission method in a lab-scale ramjet combustor. From the experimental results, we concluded that hexane vapor mole fraction increased with temperature rise and kept nearly constant during the variation of fuel to air momentum ratio.

• Journal of the Korean Society of Safety
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• v.20 no.3 s.71
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• pp.105-111
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• 2005

An experimental study is performed for extinguishing of n-heptane pool fire by water mist containing potassium acetate as a fire suppression additive. Water mist was generated by a single pressure nozzle in a small-scale chamber. The drop size distribution of water mist was measured using laser diffraction(Malvern particle sizer). The flame temperature, oxygen concentration and carbon monoxide concentration were measured. In case of using additives, the fire extinguishing time 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, were reacted as a scavenger of the major radical species OH, H which were generated for combustion process. Moreover, at a high pressure of 4MPa, the fire was extinguished through blowing effect as well as primary extinguishing mechanisms.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2009.04a
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• pp.483-486
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• 2009

국제사회의 할론계 소화약제 사용규제가 본격화 되면서 차세대 소화약제에 대한 개발은 시급한 사안으로 다가왔다. 그중에서도 청정소화약제에 해당하는 가스계 소화약제의 개발은 상당히 진척되었으며, 가스계 소화약제의 소화성능에 관한 평가는 화재발생시 인명과 재산상의 손실을 최소화하기 위한 중요한 평가요소이다. 본 연구는 기존의 이산화탄소 소화약제와 새로운 형태의 소화약제인 Novec의 소화성능을 비교 평가하기 위해서 Cup Burner Test를 이용하여 실험을 행하였으며, 에탄올, 노르말헵탄, 톨루엔과 가솔린을 원료하여 실험한 결과 Nocvec의 소화성능이 이산화탄소 소화약제보다 우수한 것으로 나타났다.

• Analytical Science and Technology
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• v.30 no.5
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• pp.287-294
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• 2017

As the demand for natural gas increases with industrial development, the supply of natural gas is expected to become unstable with a shortage of imported natural gas. It is hence necessary to meet this demand by introducing and developing various types of natural gas, such as pipeline natural gas (PNG) and substituted natural gas (SNG), in addition to liquefied natural gas (LNG). The components included in PNG as well as their concentrations must be measured accurately, and a standard gas should be developed to accurately measure hydrocarbons ($C_6-C_{10}$), which are trace components included in natural gas. The components in the primary standard gas mixtures (PSMs) developed in the present study were hexane, heptane, octane, nonane, and decane with concentrations of $10-30{\mu}mol/mol$ with methane as the balance gas. Standard hydrocarbon ($C_6-C_{10}$) gas mixtures were prepared in aluminum cylinders by a gravimetric method with traceability following ISO 6142 with raw material gases, for which the purity of each component was analyzed completely. The prepared standard gas mixtures were analyzed by to evaluate the preparation consistency between the standard gas mixtures, the adsorbability of the cylinders, the variation of the stability, and the uncertainty. The results showed that aluminum cylinders have little adsorptive loss on their internal surfaces with excellent long-term stability. The developed standard gas mixture, containing hexane, heptane, octane, nonane, and decane with concentrations of $10-30{\mu}mol/mol$, showed an uncertainty in a range of 0.79 % - 1.63 %.

• Applied Chemistry for Engineering
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• v.9 no.2
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• pp.261-267
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• 1998

We have investigated the stability of macroemulsions of AOT prepared from Winsor systems. The emulsion system was prepared from heptane+aqueous NaCl+AOT. As the concentration of NaCl increases, the stability of the emulsion increases, reaches a maximum, and then decreases. At low salt concentration the creaming occurred due to density difference of oil and aqueous phases. We developed a model for the creaming. Behavior of the emulsions containing low salt could be described very well by the model, however, at high salt concentration the electrostatic repulsion decreased due to screening and droplets started to attract each other and the stability of the emulsion decreased.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.698-701
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• 2011

Over recent several years, researches for the less sensitive gun propellant development have been carried out with promising the product of propellants which have temperature independent characteristics using the new energetic plasticizing mixture as Di-nitro-diaza-alkanes. During this study, the promising propellant formulation having temperature ballistic properties as well as better behaviors concerning the cold brittleness of the materials was confirmed by results in tests of a closed bomb and 40mm Gun firing. On-going research on the optimized shape, formulation and processes of the propellant is progressing. From now on it should be done present study to establish the better composition and processes.