• 한국항공우주학회지
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• 제34권7호
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• pp.89-96
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• 2006

액체 로켓의 가스발생기의 연소 온도는 터빈 깃의 열 손상을 방지하기 위하여 1,000K 이하로 유지되며 이를 위하여 농후 연소 또는 산화제 과다 연소를 유지한다. 이러한 이유로 연소는 비평형 화학반응이 주로 발생하며 연소반응을 예측하기가 매우 어렵다. 한편 케로신은 여러 가지 탄화수소 연료로 이루어진 혼합연료로 화학반응 메커니즘에 대한 모델이 매우 어려운 실정이다. 본 연구에서는 Dagaut가 개발한 207 화학종, 1592 화학반응 단계를 이용하였으며 완전혼합반응기 연소모델을 적용하여 계산하였다. 계산결과와 실험결과를 비교하여 보면 사용된 화학반응 기구가 검댕 예측을 하지 않고 있음에도 불구하고 계산 결과는 연소가스 온도 뿐 아니라 가스 물성치 등을 매우 잘 예측하고 있음을 확인하였다.

• 한국환경과학회지
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• 제20권1호
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• pp.119-126
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• 2011

In this study, reaction model and reactions rate accelerated by o-iodosobenzoate ion(IB$^{\ominus}$) on hydrolysis reaction of p-nitrophenyl valate(NPV) using ethyl tri-octyl ammonium mesylate(ETAMs) for quaternary ammonium salts, the phase transfer catalysis(PTC) reagent, were investigated. The effect of IB$^{\ominus}$ on hydrolysis reaction rate constant of NPV was weak without ETAMs solutions. Otherwise, in ETAMs solutions, the hydrolysis reactions exhibit higher first order kinetics with respect to the nucleophile, IB$^{\ominus}$, and ETAMs, suggesting that reactions are occurring in small aggregates of the three species including the substrate(NPV), whereas the reaction of NPV with OH$^{\ominus}$ is not catalyzed by ETAMs. Different concentrations of NPV were tested to measure the change of rate constants to investigate the effect of NPV as substrate and the results showed that the effect was weak. This means the reaction would be the first order kinetics with respect to the nucleophile. This behavior for the drastic rate-enhancement of the hydrolysis is referred as 'Aggregation complex model' for reaction of hydrophobic organic ester with o-iodosobenzoate ion(IB$^{\ominus}$) in hydrophobic quarternary ammonium salt(ETAMs) solutions.

• Korean Chemical Engineering Research
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• 제51권1호
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• pp.58-67
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• 2013

PBT (polybutylene terephthalate)는 저흡수율, 치수 안정성, 내마모성 등 기계적 특성이 우수하며, 전기전자 부품, 자동차 부품, 각종 정밀 부품에 사용된다. DMT (dimethyl terephthalate)와 BD (1,4-butandiol)를 사용하여 PBT의 원료단량체인 BHBT (bis-hydroxybutyle terephthalate)를 생산하는 에스테르 교환 반응 반응에 대해 연구 하였다. 촉매로는 zinc acetate가 사용되었다. 기존의 연구에서는 반응 중 생성 메탄올이 제거되는 반회분식 반응기를 통한 kinetics 연구가 이루어져 역반응이 고려되지 않음에 따른 모델의 부정확함이 있었다. 본 연구에서는 회분식 반응기를 사용하고 반응 중 DMT와 메탄올 양을 정량하여 생성되는 MHBT (methyl hydroxylbutylene terephthalate)와 BHBT를 추정할 수 있도록 하고, 이 반응들에서 역반응들을 고려할 수 있도록 하여 보다 정확한 모델을 제안하였다. 다양한 반응속도 모델을 제시하였고, 이 모델들이 예측한 값들이 실험 데이터와 잘 일치함을 보였다.

• 한국연소학회지
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• 제21권4호
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• pp.23-29
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• 2016

Reactivity of gasification defined by bouardard reaction is critical parameter in efficiency of the gasifier. In this study, char reactivity of the gasification was derived from the experiments using the intrinsic reaction kinetics model. Pressurized wire mesh heating reactor (PWMR) can produce high temperature and high pressure conditions up to 50 atm and 1750 K, respectively and PWMR was designed to evaluate the intrinsic reaction kinetics of $CO_2$ gasification. In this study, Kideco and KCH (sub-bituminous Indonesian coal) were pulverized and converted into char. Experiments used the PWMR were conducted and the conditions of the temperature and pressure were 1373~1673 K, 1~40 atm. To distinguish the pressure effect from high pressurized condition, internal and external effectiveness factors were considered. Finally, the intrinsic kinetics of the Kideco and KCH coal char were derived from $n^{th}$ order reaction rate equations.

• 청정기술
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• 제19권1호
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• pp.51-58
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• 2013

니켈 촉매 상에서 에탄의 수증기 개질 반응과 수성가스 전환반응 반응에 대한 반응속도 데이터를 얻기 위하여 반응온도와 반응물의 분압을 변화시키면서 반응 실험을 수행하였다. 반응속도 데이터를 사용하여 거듭제곱 속도식 모델(power law kinetic model)과 랭미어-힌쉘우드 모델(Langmuir-Hinshelwood model)의 매개변수를 구하였다. 또한 반응 속도 모델식을 적용하여 PRO/II를 이용한 공정 모사를 통해서 에탄의 수증기 개질 반응기 사이징(sizing)을 수행하였다. 에탄을 반응물로 하여 수증기 개질 반응을 수행한 결과, 단순한 거듭제곱 속도식 모델보다 표면반응에 의하여 반응속도가 결정되는 랭미어-힌쉘우드 모델이 보다 적합하였고, 수성가스 전환반응에 대한 반응속도식은 거듭제곱 속도식 모델이 적합함을 보였다. PRO/II 시뮬레이션을 통해서 수소 생산량에 필요한 반응기의 크기를 결정할 수 있었다.

• 공업화학
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• 제17권1호
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• pp.33-36
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• 2006

광경화 접착제로 많이 사용되는 우레탄-아크릴레이트 올리고머의 광경화 거동을 자체촉매화 반응모델식을 통해 중합온도 및 올리고머의 관능성에 따른 영향을 확인하여 보았다. 중합온도가 증가함에 따라 최대중합속도는 감소하여 중합온도가 경화 거동에 대한 영향인자임을 확인할 수 있었으며, 반응속도상수 k는 온도증가에 따라 거의 일정한 값을 보이나 반응차수 m과 n은 증가하는 경향을 보였는데 이는 가교구조에 의한 반응성 기의 확산제한 및 유동성의 제한으로 인한 것으로 판단되어진다. 온도증가에 따른 중합속도의 감소는 주로 반응차수 n의 증가에 의해 진행되었다.

• 한국환경보건학회지
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• 제14권1호
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• pp.11-22
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• 1988

Calcium oxide, lithium oxide and titanium oxide were investigated as additives of zinc oxide for the removal of hydrogen sulfide at high temperature. This experiment was performed in the range of 1.0-2.0 vol.% H$_2$S concentration at 623-873 K reaction temperature, using a thermogravimetric analyzer. A pore blocking model was found to fit the reaction rate and the kinetics data were sucessfully expressed by this model. The reactions between additive sorbents and hydrogen sulfide were first order with respect to hydrogen sulfide concentration in a gaseous mixture with nitrogen. Among the used sorbents, ZnO-CaO 0.5 at.% and ZnO-TiO$_2$ 2.0 at.% sorbents had the best additive effects on the sulfidation reaction between additive sorbents and hydrogen sulfide, whereas the ZnO-Li$_2$O sorbents were ineffective.

• Bulletin of the Korean Chemical Society
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• 제31권10호
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• pp.2877-2883
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• 2010

The folding kinetics of $WT^*$ ubiquitin variant with valine to alanine mutation at sequence position 26 (HubWA) was studied by stopped-flow fluorescence spectroscopy. While unfolding kinetics showed a single exponential phase, refolding reaction showed three exponential phases. The semi-logarithmic plot of urea concentration vs. rate constant for the first phase showed v-shape pattern while the second phase showed v-shape with roll-over effect at low urea concentration. The rate constant and the amplitude of the third phase were constant throughout the urea concentrations, suggesting that this phase represents parallel process due to the configurational isomerization. Interestingly, the first and second phases appeared to be coupled since the amplitude of the second phase increased at the expense of the amplitude of the first phase in increasing urea concentrations. This observation together with the roll-over effect in the second folding phase indicates the presence of intermediate state during the folding reaction of HubWA. Quantitative analysis of Hub-WA folding kinetics indicated that this intermediate state is on the folding pathway. Folding kinetics measurement of a mutant HubWA with hydrophobic core residue mutation, Val to Ala at residue position 17, suggested that the intermediate state has significant amount of native interactions, supporting the interpretation that the intermediate is on the folding pathway. It is considered that HubWA is a useful model protein to study the contribution of residues to protein folding process using folding kinetics measurements in conjunction with protein engineering.

• 한국환경보건학회지
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• 제30권2호
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• pp.133-139
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• 2004

The objective of this study was to investigate the destruction efficiency and to determine the fundamental parameters of oxidation kinetics under the supercritical water(SCW) condition. Target material was cephradine, toxic and antibiotic material, in the pharmaceutical wastewater. For this purpose, the effect of reaction temperature and oxidant were investigated on the destruction efficiency of cephradine. And the oxidation kinetics of cephradine was derived by using a empirical power-law model. The experiment was carried out in a cylindrical batch reactor made of Hastelloy C-276 which was endurable high temperature and pressure. The destruction efficiency of cephradine increased with increment of the temperature and reaction time. Also the type of oxidants was effected and oxidants(Air and $H_2O$$_2$) were enhanced the destruction efficiency. The global oxidation kinetics for cephradine has led to two rate expressions according to type of oxidant. - In the presence of air oxidant: Rate=k. $e^{-Ea}$RT/(Ceph.)$^{1.0}$ ( $O_2$)$^{0.51}$$\pm$0.05(k=3.27${\times}$$10^{5}$ sec. Ea=63.25 kJ/mole) - In the presence of $H_2O$$_2$ oxidant : Rate=kㆍ $e^{-Ea}$RT/(Ceph.)$^{1.0}$ ($H_2O$$_2$)$^{0.62}$$\pm$0.02(k=2.76${\times}$$10^4$/sec. Ea=47.65 kJ/mole)ole))

• 한국자동차공학회논문집
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• 제20권5호
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• pp.71-80
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• 2012

To improve the $NO_X$ conversion over a SCR (selective catalytic reduction) catalyst, the DOC (diesel oxidation catalyst) is usually placed upstream of the SCR catalyst to enhance the fast SCR reaction ($4NH_3+2NO+2NO_2{\rightarrow}4N_2+6H_2O$) using equimolar amounts of NO and $NO_2$. Here, a ratio of $NO_2/NO_X$ above 50% should be avoided, because the reaction with $NO_2$ only ($4NH_3+4NO+O_2{\rightarrow}4N_2+6H_2O$) is slower than the standard SCR reaction ($4NH_3+4NO+O_2{\rightarrow}4N_2+6H_2O$). In order to accurately predict the performance characteristics of SCR catalysts, it is therefore desired to develop a more simple and reliable mathematical and kinetic models on the oxidation kinetics of nitric oxide over a DOC. In the present work, the prediction accuracy and limit of three different chemical reaction kinetics models are presented to describe the chemicophysical characteristics and conversion performance of DOCs. Steady-state experiments with DOCs mounted on a light-duty four-cylinder 2.0-L turbocharged diesel engine then are performed, using an engine-dynamometer system to calibrate the kinetic parameters such as activation energies and preexponential factors of heterogeneous reactions. The reaction kinetics for NO oxidation over Pt-based catalysts is determined in conjunction with a transient one-dimensional (1D) heterogeneous plug flow reactor (PFR) model with diesel exhaust gas temperatures in the range of 115~$525^{\circ}C$ and space velocities in the range of $(0.4{\sim}6.5){\times}10^5\;h^{-1}$.