• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.7
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• pp.841-848
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• 1997

Combustion of gaseous fuel combustor in a high temperature vitiated air stream was studied with computer simulation. It is for application to afterburner of gas turbine engine which the exact mechanism is not yet clarified. As the jet velocity from fuel nozzle is very high and the geometry of combustor is three dimensional complex structure, many time and money are required to have good results. To consider this demerit, it is simplified to 2-dimensional and modified with the nozzle hole area to same area of annual status. As the thickness of annual is too thin, it is to divide with the many grids for reasonable results. Accordingly, new method which injected fuel mass, momentum and energy are added to source terms of each governing conservation equation as a source terms is introduced like as two phase analysis. Reaction rate is determined by taking into account the Arrhenius reaction based on a single step reaction mechanism. It is focused to temperature and product concentration distribution at each equivalence ratio of inlet hot product.

• Journal of the Korean Chemical Society
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• v.30 no.3
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• pp.282-288
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• 1986

Kinetic studies were carried out for the substitution of $H-2$O for $Cl^-$ ligand of chloropentaamminecobalt(III) in the presence of $Hg^{2+}$ catalyst by UV spectrophotometer. It has been found that $Hg^{2+}$ ion appears first order dependence and the overall reaction is second order. The reaction system can be believed to occur via $S_N2$ reaction, because the calculated rate equation for our presumed $S_N2$ mechanism is in agreement with the observed one.

• Journal of the Korean Ceramic Society
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• v.26 no.2
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• pp.195-200
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• 1989

The Silica-Carbon mixture was made with addition of carbon black in the composition which monodispersed spherical fine silica was formed by the hydrolysis of ethylsilicate, mole ratio of Carbon/Alkoxide was 3.1 and $\beta$-SiC powder was synthesized by reacting this mixture at 1,350~1,50$0^{\circ}C$ in Ar atmosphere. The results of this study are as follow : (1) The purity of synthesized $\beta$-SiC powder was above 99.98% and it was in cubic modification with lattice constant of 4.3476$\AA$. (2) The rate-controlling steps varied with the reaction temperature for the syntehsis of $\beta$-SiC in this study ; nucleation and growth of $\beta$-SiC at 1,350~1,40$0^{\circ}C$, interfacial reaction at 1,45$0^{\circ}C$ and diffusion described by Jander Equation at 1,50$0^{\circ}C$. (3) When the rate-determining step was nucleation and growth, the activation energy was about 87.8kcal/mol.

• Journal of the Korean Chemical Society
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• v.36 no.4
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• pp.558-564
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• 1992

Product yields were determined for the reaction of styrene with sodium hypochlorite (NaOCl) in CH$_2$Cl$_2$ with various substituted manganese porphyrin complexes as catalysts. In the presence of the electron withdrawing group and ortho-substituted manganese porphyrin complexes, reaction rate and epoxide selectivity are increased. Also reaction rate and epoxide selectivity are largely increased by the presence of imidazole which behaves as axial ligand of the manganese porphyrin complexes. By the kinetic study with Michealis-Menten equation, the factor significantly affected to catalytic ability is $K_m$ value. A large binding affinity consists with the low $K_m$. With theoretical analysis by EHMO calculation, the results are in good agreement with experimental data.

• Bulletin of the Korean Chemical Society
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• v.1 no.1
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• pp.10-17
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• 1980

Penicillin amidohydrolase was partially purified from the fermented broth of Bacillus megaterium, and was immobilized on nylon fiber. The surface area of nylon fiber was increased by roughening it with fine sand and activated by acid treatment. The free amino groups on the nylon fiber exposed by such treatment were then utilized to immobilize the penicillin amidase. Enzymatic properties of penicillin amidohydrolase immobilized on the nylon fiber by covalent bonding and cross linking with glutaraldehyde were studied and compared with those of soluble enzyme. The optimal pH and temperature profile of immobilized enzyme showed only slightly broader peaks, and the values of kinetic constants, $K_m$, $K_{ia}$, and $K_{ip}$, of the immobilized enzyme are only slightly greater than those of the soluble enzyme. These results suggest that the mass transfer effect on the reaction rate for the penicillin amidase immobilized on nylon fiber is not so significant as the enzyme immobilized on some other support material like bentonite. The experimental results of batch reaction agreed well with the results of computer simulation for both the immobilized and soluble enzyme systems, confirming the validity of the rate equation derived which was based on the combined double inhibition by two reaction products.

• Journal of Soil and Groundwater Environment
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• v.18 no.3
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• pp.65-72
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• 2013

Adsorption of melamine was examined using columns packed with granular activated carbon (GAC). Raw GAC was sieved with 20, 40, 60 and 80 mesh to determine the influence of adsorbent particle size on reaction and diffusion. The mass ratio of the adsorption capacity of GAC for melamine ranged from 9.19 to 11.06%, and adsorption rates increased with decreasing particle size within this range. Rate constants between 3.295 ~ 4.799 $min^{-1}$ were obtained using a pseudofirst-order equation that was used to determine adsorption kinetics. A surface diffusion model was adapted to take into account the unsteady-state equation of a spherical adsorbent by converting the surface concentration from a constant to a variable governed by a dispersion equation. The calculated values were fit with the experimental results by using the diffusion coefficients as regression parameters. The modified equation exhibited a more precise agreement with respect to the sum of the absolute error (SAE).

• Journal of the Korean Chemical Society
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• v.32 no.5
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• pp.476-482
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• 1988

Kinetic studies and theoretical investigations were made to illustrate the mechanism of the aquation of cis-[Co(en)$_2$YCl]$^{r+}$ (Y = NH$_3$, NO$_2^-$, NCS$^-$, $H_2O$) in $Hg^{2+}$ aqueous solution UV/vis-spectrophotometrically. The aquation of cis-[Co(en)$_2$YCl]$^{r+}$ have been found to be the second order for overall reaction as first order for each of substrate and Hg$^{2+}$+ catalyst. The reaction rate was increased in the order of Y=NH$_3$ < NCS$^-$- < $H_2O$ < $NO_2^-$, which are neighboring group of Cl. The step of bond formation was found to be the rate determining one, because the net charge of central metal ion run parallel with the observed rate constant. On the basis of rate determining step, kinetic data and the observed activation parameters, we have proposed the Id mechanism for the reaction system. The rate equation derived from the proposed mechanism has been in agreement with the observed rate equation.

• Journal of the Korean Chemical Society
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• v.17 no.5
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• pp.363-370
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• 1973

The rate constants of the nucleophilic addition of n-propyl-mercaptan to $\alpha$-cyano-$\beta$-piperonylacrylic acid were determined at various pH and a rate equation which can be applied over wide pH range is obtained. The rate equation reveals that below pH 4.5 the reaction is initiated by the attack of n-propylmercaptan to $\alpha$-cyano-$\beta$-piperonylacrylic acid. At pH 4.5~6.5, however, n-propylmercaptan is added to $\alpha$-cyano-$\beta$-piperonylacrylate ion; at pH 7.04~9.5 the competitive reaction between n-propylmercaptan and n-propylmercaptide ion is anticipated to occur. Above pH 10 the addendum is n-propylmercaptide ion and the acceptor is $\alpha$-cyano-$\beta$-piperonylacrylate ion.

• Journal of the Korean Chemical Society
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• v.32 no.3
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• pp.260-266
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• 1988

The rate constants for the nucleophilic addition reactions of thioglycolic acid and cysteine to ${\beta},\;{\beta}$-dichlorostyrene derivatives(p-H, p-Cl, $p-CH_3,\;and\;p-OCH_3$) were photochemically determined at various pH and a rate equation which can be applied over a wide pH range was obtained. On the bases of rate equation, general base catalysis and substituent effect, the plausible addition reaction mechanism was proposed: Above pH 9.0, the reaction was initiated by the addition of sulfide anion, and in the range of pH 7.0 to 9.0, the neutral molecules and it's anions attacked to the double bond, competitively. However, below pH 7.0, only the neutral molecules of thioglycolic acid or cysteine added to the carbon-carbon double bond.

• Microbiology and Biotechnology Letters
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• v.15 no.2
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• pp.98-103
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• 1987

Two phase reaction system was used to hydrolyze the olive oil for fat splitting. Kinetics of lipases in two phase system were investigated by determining the hydrolysis rate of triglycerides at various olive oil concentrations in isooctane using the microbial lipases from Candida rugosa and Rhizopus arrhizus. The rate equation in lipid hydrolysis for various olive oil concentrations in two phase system was deviated from the Michaelis-Menten kinetics. The results suggested that the olive oil concentration in isooctane affects the interfacial area. The dependency of the interfacial area on olive oil concentration is greater at the lower olive oil concentration than at the higher substrate concentration. We modified the rate equation by considering the interfacial area between two phases depending on the olive oil concentration in solvent phase.