• Bulletin of the Korean Chemical Society
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• 제21권1호
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• pp.101-104
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• 2000

Li-graphite intercalation compounds (GICs), synthesized at elevated temperature and pressure, were allowed to decompose spontaneously in the atmosphere. The decomposition processes were analyzed by of X-ray diffraction, DSC analysis, FT-IR measurements, UV/VIS spectrophotometry. The deintercalation reaction of the Li-GICs ceased after 6 weeks and only the residual compounds could be observed. A strong exothermic reaction was observed at 300 $^{\circ}C$ in thermal decomposition, and relatively stable decomposition curves were formed. A few endothermic curves have been observed at 1000 $^{\circ}C.$ After 6 weeks deintercalation reaction time of GICs, many exothermic and endothermic reactions were accompanied at the same time. In addition the reactions of the functional groups such as aromatic rings, nitrogen, $-CH_3$, $-CH_2$ etc. of GDIC obtained by the above reaction were confirmed by FT-IR spectrum. UV/VIS spectrophotometric measurement clearly shows the formation of a minimum energy value ($R_{min}$) for the compounds between Li-GICs as a starting material and Li-GDICs obtained until after 3 weeks of the deintercalation reaction, while they were no clear energy curves from 4 weeks of reaction time, because of the formation of the graphite structure, of high stages and of the Li compounds surrounding the graphite in the deintercalation reaction.

• 보존과학회지
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• 제28권2호
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• pp.131-139
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• 2012

석조문화재의 보존 복원 과정에 적용되는 에폭시 수지에 경화제의 혼합을 통하여 경화 시 발열 반응을 제어할 수 있는 접착 시스템을 연구하였다. 사용된 에폭시 주제는 hydrogenated bisphenol A (HBA), 경화제로는 속경화형 경화제 FH와 poly(propyleneglycol)bis(2-aminopropylether) (SH)를 사용하였으며, 무기 첨가물은 탈크를 사용하였다. 에폭시 수지와 경화제의 혼합비에 따라 경화 시 온도를 측정하고, differental scanning calorimeter (DSC)를 이용하여 경화동력학을 확인하였으며, 기계적 특성을 파악하기 위해 무기 첨가물의 함량에 따른 인장강도, 전단강도를 측정하였다. 연구 결과, 에폭시 수지의 경화제 혼합을 통하여 경화 시 반응열 상승폭 제어 및 경화 거동 제어의 가능성을 확인하였으며, 무기 첨가물 첨가를 통해 적절한 강도 조절이 가능하여 석조문화재에 적용 가능한 새로운 접착 시스템을 개발하였다.

• 전기학회논문지
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• 제56권7호
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• pp.1255-1260
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• 2007

[ $TiO_2-V_2O_5$ ] sol was prepared using sol-gel method. Sol changed to gel with hydrolysis and polymerization. DTA properties of gel powder had endothermic reaction due to evaporation of propanol about $80^{\circ}C$, had exothermic reaction due to combustion of propanol about $230^{\circ}C$ and had exothermic reaction due to combustion of alkyl group about $350^{\circ}C$. Crystalline properties of gel powder retained amorphous phase at $50^{\circ}C$, retained anatase phase from $400^{\circ}C\;to\;600^{\circ}C$ and had all rutile phase over $700^{\circ}C$ at 0.01mole $V_2O_5$ additive. The capacitance of thin films increased with increasing heat treatment temperature and thin films had best properties at $700^{\circ}C$. The capacitance of thin films increased a lot with decreasing measurement frequency.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제11권3호
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• pp.7-20
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• 2007

We examined the steady state solution for a strongly exothermic mixtures in some class A geometries subjected to different boundary conditions under Arrhenius, Bimolecular and Sensitised reactions. The solution of the governing nonlinear reaction diffusion equation was obtained using the variational method formulation executed in Mathematica package. The paper elucidates the influence of geometry, boundary conditions and types of reaction on the thermal ignition of the reactive mixture. Apart from validating known results in literature, the solution gave further insight into the influence of material properties and conditions on the occurrence of thermal ignition.

• 한국수소및신에너지학회논문집
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• 제24권2호
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• pp.113-120
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• 2013

A steam reformer is a chemical reactor to produce high purity hydrogen from fossil fuel. In the steam reformer, since endothermic steam reforming is heated by exothermic combustion of fossil fuel, the heat transfer between two reaction zones dominates conversion of fossil fuel to hydrogen. Steam Reforming is complex chemical reaction, mass and heat transfer due to the exothermic methane/air combustion reaction and the endothermic steam reforming reaction. Typically, a steam reformer employs burner to supply appropriate heat for endothermic steam reforming reaction which reduces system efficiency. In this study, the heat of steam reforming reaction is provided by anode-off gas combustion of stationary fuel cell. This paper presents a optimization of heat transfer effect and average temperature of cross-section using two-dimensional models of a coaxial cylindrical reactor, and analysis three-dimensional models of a coaxial cylindrical steam reformer with chemical reaction. Numerical analysis needs to dominant chemical reaction that are assumed as a Steam Reforming (SR) reaction, a Water-Gas Shift (WGS) reaction, and a Direct Steam Reforming(DSR) reaction. The major parameters of analysis are temperature, fuel conversion and heat flux in the coaxial reactor.

• Bulletin of the Korean Chemical Society
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• 제30권9호
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• pp.2051-2056
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• 2009

The rate constants of alkaline fading of malachite green ($MG^+$) was measured in the presence of nonionic (TX-100), cationic (DTAB) and anionic (SDS) surfactants. This reaction was studied under pseudo-first-order conditions at 283∼303 K. The rate of fading reaction showed noticeable dependence on the electrical charge of the used surfactants. It was observed that the reaction rate constants were increased in the presence of TX-100 and DTAB and decreased in the presence of SDS. According to Hughs-Ingold rules for nucleophilic substitution reactions, the electric charge of MG/surfactant compound along with decrease in dielectric constant of $MG^+$ micro-environment in this compound varies the rate of fading reaction. Binding constants of surfactant molecules to $MG^+$ were calculated using cooperativity, pseudo-phase ion exchange and classical models and the related thermodynamic parameters were obtained by classical model. The results show that the binding of $MG^+$ to TX-100 is exothermic and binding of $MG^+$ to DTAB and SDS in some concentration ranges of the used surfactants is endothermic and in the other ones is exothermic.

• 한국안전학회지
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• 제25권3호
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• pp.61-65
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• 2010

Most of the chemical reactions performed in the chemical industry are exothermic, meaning that thermal energy is released during the reaction. It is also important to understand the thermal hazards such as thermal stabilities and runaway reactions, which are governed by thermodynamics and reaction kinetics of the mixed materials. The paper was described the evaluation of thermal behavior caused by an exothermic batch process in manufacture of the vinyl acetate resin. The aim of the study was to evaluate the thermal stabilities of raw materials with operating conditions such as a reaction inhibitor, heating rate, reaction atmosphere and the mount of methanol charged in the vinyl acetate polymerization process. The experiments were performed in the differential scanning calorimeter(DSC), C 80 calorimeter, and thermal screening unit($TS^u$). It was suggested that we should provide the thermal characteristics for raw materials to present safe precautions with operating conditions in the vinyl acetate polymerization process.

• 한국태양에너지학회 논문집
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• 제22권1호
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• pp.9-21
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• 2002

To develope chemical heat pump using available energy sources, solar heat and other kinds of waste thermal energy, we have studied the heat transfer rate in cylindrical bed reactor packed with calcined Dolomite. Two dimensional (radial and circumferential) Partial differential equations, concerning heat and mass transfer in packed bed of calcined Dolomite, are solved numerically to describe the characteristics of the reaction of calcined Dolomite and heat transfer. The results obtained by numerical analysis about two dimensional profiles of temperature and conversion of reactant in the packed bed reactor and the amount of exothermic heat released from the reactor are follows. It was found that all of calcined Dolomite packed bed kept the reaction temperature of about 750K throughout the entire part of the bed, immediately after the steam was introduced exothermic reaction of hydration was proceeded from the packed bed inpu to output and from wall side to center. The rate of thermochemical reaction depends on the temperature and concentration and it is also governed by the boundary conditions and heat transfer rate in the particle packed bed.

• 태양에너지
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• 제17권1호
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• pp.67-77
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• 1997

본 연구는 에너지 밀도와 승온효과가 큰 화학 열펌프시스템 개발을 위해 무기 수화물계인$Ca(OH)_2/CaO$ 원주형 충전층내 핀을 주입 전열 촉진한 경우에 있어서 반응촉진 효과의 이론적 평가를 행하였다. 그 결과 충전층내 수화 탈수 반응시 반응층내 시간에 따른 온도 분포변화 및 반응율 분포에 대한 수치 해석 결과 전열핀 주입에 따른 반응완결 시간이 절반이하로 줄일 수 있다고 한 실험결과와 잘 일치됨을 알 수 있었다. 또한 해석결과 열화학 반응은 주로 온도 및 농도에 의존하였고 경계조건과 입자 충전층의 열전도에 의해 크게 좌우됨을 알 수 있었다.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2000년도 춘계학술발표대회 논문집
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• pp.53-58
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• 2000

During the curing process of thick glass/epoxy laminates, a substantial amount of temperature lag and overshoot at the center of the laminates is usually experienced due to the large thickness and low thermal conductivity of the glass/epoxy composites. Also, it requires a longer time for full and uniform consolidation. In this work, temperature, degree of cure and consolidation of a 20mm thick unidirectional glass/epoxy laminate were investigated using an experiment and a 3-dimentional numerical analysis considering the exothermic reaction. From the experimental and numerical results, it was found that the experimentally obtained temperature profile agreed well with the numerical one and the cure cycle recommended by the prepreg manufacturer should be modified to prevent a temperature overshoot and to obtain full consolidation.