• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.279-286
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• 2010

Hypersonic aircraft technologies have been developed with increase in flight speeds. As hypersonic flight speeds increase, heat loads on an aircraft and it's engine increase. Researches on cooling technologies using endothermic fuels are progressing in the USA, France, and Russia to treat the heat loads. Endothermic fuels are liquid hydrocarbon aircraft fuels which are able to absorb the heat loads by undergoing endothermic reactions, such as thermal and catalytic cracking. In this study, methylcyclohexane, n-octane, and n-dodecane were selected as model endothermic fuels and experiments in endothermic properties were implemented. Experimental conditions were supercritical phase of each model fuels in which actual endothermic fuels were exposed. The object of this study is to identify endothermic properties of the model endothermic fuels and to predict endothermic properties of actual fuels such as kerosene fuels.

• Clean Technology
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• v.26 no.3
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• pp.161-167
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• 2020

For the design of the prevention and mitigation measures in process industries involving flammable substances, reliable safety data are required. An important property used to estimate the risk of fire and explosion for a flammable liquid is the flash point. Flammability is an important factor to consider when developing safe methods for storing and handling solids and liquids. In this study, the flash point data were measured for the binary systems {2-butanol + 2,2,4-trimethylpentane}, {2-butanol + methylcyclohexane} and {2-butanol + toluene} at 101.3 kPa. Experiments were performed according to the standard test method (ASTM D 3278) using a Stanhope-Seta closed cup flash point tester. A minimum flash point behavior was observed in the binary systems as in the many cases for the hydrocarbon and alcohol mixture that were observed. The measured flash points were compared with the predicted values calculated via the following activity coefficient (GE) models: Wilson, Non-Random Two-Liquid (NRTL), and UNIversal QUAsiChemical (UNIQUAC) models. The predicted data were only adequate for the data determined by the closed-cup test method and may not be appropriate for the data obtained from the open-cup test method because of its deviation from the vapor liquid equilibrium. The predicted results of this work can be used to design safe petrochemical processes, such as the identification of safe storage conditions for non-ideal solutions containing flammable components.

• Fire Science and Engineering
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• v.31 no.3
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• pp.19-24
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• 2017

Flammable substances are used in laboratories and industrial process. The flash point (FP) is one of the most important physical properties used to determine the potential for characterizing the fire and explosion hazard of liquids. The FP data at 101.3 kPa were measured for the binary systems {toluene+ethylbenzene}, {methlycyclohenxane+ethylbenzene} and {n-heptane+ ethylbenzene}. The experiments were performed according to the standard test method (ASTM D 3278) using a SETA closed cup flash point tester. The measured FPs were compared with the values predicted using the following activity coefficient models: Wilson, Non-Random Two Liquid (NRTL), and UNIversal QUAsiChemical (UNIQUAC). The average absolute deviation between the predicted and measured lower FP was less than 1.74 K.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.5
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• pp.32-39
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• 2018

Supercritical injection behavior of liquid hydrocarbon compounds, which are used as main components of propellant fuel, was analyzed. Decane and Methylcyclohexane (MCH) with different critical points were selected as experimental fluid and Shadowgraphy technique was used. Decane and MCH behave differently in the initial state under the subcritical condition. However, near the critical point, the enthalpy of evaporation became close to 0, so that phase change into supercritical fluid occurred, not vaporization process, and no breakup of both fluids occurred.

• Korean Chemical Engineering Research
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• v.57 no.5
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• pp.611-619
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• 2019

This study was carried out to investigate fuel decomposition characteristics and coke formation according to types of endothermic fuels and methods of catalyst molding. Methylcyclohexane (MCH), n-dodecane, and exo-tetrahydrodipentadiene (exo-THDCP) were used as the endothermic fuels. As a catalyst, USY720 supported with platinum was used. It was manufactured by only using pressure to disk-type, or pelletized with a binder and a silica solution. The characteristics of the catalysts according to the molding method were analyzed by X-ray diffraction analysis, scanning electron microscopy, nitrogen adsorption-desorption isotherm, and ammonia temperature programmed desorption analysis. The reaction was carried out under conditions of high temperature and high pressure ($500^{\circ}C$, 50 bar) in which the fuel could exist in a supercritical state. The product was analyzed by gas chromatograph/mass spectrometer and the coke produced by the catalyst was analyzed by thermogravimetric analyzer. After the reaction, the composition of the products varied greatly depending on the structure of the fuel. In addition, the crystallinity and surface properties of the catalysts were not changed by the method of catalyst molding, but the changes of the acid sites and the pore characteristics were observed, which resulted in changes in the amount and composition of products and coke.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.475-481
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• 2017

In this paper, high speed camera images were used to analyze the supercritical injection behavior of liquid hydrocarbon compounds used as main components of propellant fuel. Decane and Methylcyclohexane (MCH), which have different critical points among kerosene constituents, were selected as experimental fluid and Shadowgraphy technique was used for the analysis. The difference in the temperature variation from the initial injector state of the subcritical condition until the vaporization occurs was represented by the different behaviors of Decane and MCH. However, under the Supercritical conditions, the enthalpy of vaporization near the critical point approaches zero and the phase change to the Supercritical phase occurs instead of vaporization process. In the phase change of the Supercritical system, there was no rapid density change, so the liquid state image was observed in both the Decane and MCH.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.4
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• pp.26-33
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• 2016

In order to analyze supercritical transition of liquid hydrocarbon fuel which used propulsion engine, visualization of phase changing using Methylcyclohexane (MCH) was performed. Also, measurements of temperature and pressure were conducted to obtain saturation lines of MCH and Decane. delayed increase of the pressure existed near the critical point due to dramatical increase of specific heats and the critical opalescence was only observed from the end point of delaying to the critical point. Beyond the critical point, the boundary between phases disappeared and the strong density gradient was observed. As the comparison between experimental and numerical saturation lines, the numerical estimation for mixture had relatively little difference while the results of pure components had almost coincidence.

• Polymer(Korea)
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• v.33 no.2
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• pp.131-136
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• 2009

The effect of the chemical structure of the peroxide crosslinking agent on the reactive crosslinking reaction of EVA was investigated and the physical properties of the crosslinked EVA were studied as well. It was found that peroxide with one peroxy group (perbutyl peroxide) is more effective than peroxides with two peroxy group (2,5 dimethyl 2,5 di(tert-butylperoxyl) hexane and 1,1-di(tert-buthylperoxy)-3,3,5-tri-methylcyclohexane) in melt reactive crosslinking reaction of EVA. The rate of crosslinking was increased by the use of crosslinking acceleration agent but the noticeable effect on degree of crosslinking was not found. Crosslinking caused the lowering of melt flow ability of EVA but mechanical properties were enhanced by the crosslinking of EVA.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.54-57
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• 2006

Structure H formation experiments were conducted in a semi-batch stirred vessel using methane as the small guest substance and neohexane(NH), tert-butylmethylether(TBME) and methylcyclohexane(MCH) as the large molecule guest substance (LMGS). The results indicate that the rates of gas uptake and induction times are generally dependent on the magnitude of the driving force. When tert-butyl methyl ether is used as the LMGS rapid hydrate formation, much smaller induct ion time and rapid decomposition can be achieved. Liquid-liquid equilibrium (LLE) data for the above LMGS with water have been measured under atmospheric pressure at 275.5, 283.15K, and 298.15K. It was found that TBME is the most water soluble followed by NM and MCH. The solubility of water in the non-aqueous liquid was found to increase in the following order: MCH

• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.387-390
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• 2006

We report here that under strong attacksof external $CH_4$ guest molecules the sII and sH methane hydrates are structurally transformed to the crystalline me framework of sI, leading to favorable change of the lattice dimension of the host-guest networks. The High Power Decoupling $^{13}C$ NMR and Raman spectroscopies were used to identify structure transitions of the mixed $CH_4+C_2H_6$ hydrates (sIIl) and hydrocarbons (methylcyclohexane, isopentane) + $CH_4$ hydrates (sH). The resulting spectra indicate that most of the synthesized sII and sH hydrates were transformed to methane hydrate of sl under 110 bar and particularly the coexistence of sl with sII or sH appear according to the surrounding methane-rich gas conditions. The present findings might be expected to Provide rational evidences regarding the preponderant occurrence of naturally-occurring sI methane hydrates in marine sediments.