원형 용융탄산염 단위 연료전지에서 수성가스 전이반응의 영향

정귀영,김미현 弘益大學校 科學技術硏究所 2000 科學技術硏究論文集 Vol.11 No.-

본 연구에서는 단면이 원형인 용융탄산염 단위 연료전지에 대한 수치모사를 수행하여 수성가스 전이반응을 포함하지 않았을 때의 오차를 살펴보았다. 원통형 연료전지에서 물질수지 및 에너지수지식을 세우고 코드화하여 여러 작동 조건에서 온도분포, 전류밀도 및 가스의 전환율 등 전지의 성능을 살펴보았다. 또한, 수성가스 전이반응이 포함되지 않았을 경우와 비교하였다. 전류밀도가 일정할 때 원형 단위 연료전지의 각 부분에서의 온도분포는 대체로 고른 분포를 보였다. 전지 입구에서 수소의 농도가 높아 전기화학반응이 많이 일어나 많은 열이 발생하기 때문에 음극 가스의 온도가 상승하다가 전지의 내부에서 거의 일정하게 온도가 유지되고, 또한 전지의 바깥에 가까워질수록 전환율의 증가율이 크게 된다. 전지로 유입되는 음극 가스 중에는 일산화탄소가 없기 때문에 평형에 도달하기 위해 수성가스 전이반응이 역반응으로 빠른 속도로 진행되어 전지의 입구부분에서 기울기가 더 크게 나타난다. 전류 밀도가 같을 때 수소가스 전이반응이 포함되었을 때의 전지전압이 포함되지 않았을 때보다 더 적게 나타난다. 전지의 입구에서 수성가스 전이반응이 역반응으로 진행되어 수소가 더 소모되고 일산화탄소의 분율은 증가하게 되어 음극의 분극저항 값이 상재거으로 커지기 때문이다. Effects of the water-gas shift reaction on the pedal' lances of the circular molten carbonate unit fuel cell were studied by a mathematical modelling. After setting up the mass and the energy balance equations, performances of the unit cell, such as the temperature distributions, the current density and the conversion distribution, were obtained and compared with the case without considering the water-gas shift reaction. When the current density was constant, temperature distributions were uniform. The temperature of the anode gas increased and maintained constant, because the concentration of hydrogen was so high that the electrochemical reaction was active and a lot of heat was generated. As a result, the change of the conversion of gas was high. There is no carbon monoxide in the entering anode gas so that the water-gas shift reaction progressed reversely to reach an equilibrium state and the slope of the conversion of anode gas is high. At a same current density, the cell voltage was lower when the water-gas shift reaction was included. Since the water-gas shift reaction progressed reversely, in the direction of consuming hydrogen and generating carbon monoxide, so that the anodic polarization was relatively big.

유동층반응기에서 CVI에 의한 SiC증착된 고표면적 촉매지지체 제조에 관한 수치모사의 연구

鄭貴榮,李成柱 弘益大學校 科學基術硏究所 1999 科學技術硏究論文集 Vol.10 No.2

In this research, to improve the corrosion resistance and oxidation resistance of catalyst support in manufacturing the catalyst, the formation of SiC layer on the activated carbon by permeating SiC from dichlorodimethylsilane(DDS) into pore and depositing while the porous structure was kept was studied. Activated carbons of sizes of 4-12, 12-20, 20-40 mesh were used. The best conditions of manufacturing the support were found by studying the characteristics of SiC under various deposition conditions. The results from the mathematical modeling were compared with the experimental results. The changes of the amount of deposition, pore diameter, surface area with time were obtained by simulating convection, diffusion of DDS and reaction in isothermal reactor at steady state. The uniform deposition in the pores of sample was obtained at a lower concentration of DDS and a lower pressure. Additionally, from the observation that the pore diameter and the surface area have minimum values at a certain time of deposition, it was known that deposition occurred inside of the pore at first and then on the outside of particle.

침전조건이 침전물의 형상과 소결에 미치는 영향

鄭貴榮 弘益大學校 科學技術硏究所 1994 科學技術硏究論文集 Vol.4 No.-

Effects of the concentration of ion, the rate of adding precipitator, washing in the precipitaion process were studied. Yttrium hydroxide powders were produced from yttrium nitrate solution to which ammonium hydroxide solution was added. Particle size distribution, particle structure, and characteristics of the filtered cakes could be controlled by the proper regulation of the precipitation conditions. When yttrium concentrations were increased, an irregular chunk changed to a crystal form and then changed again to an irregular form. When more nitrate ion was added, more coagulation resulted. The morphologies of precipates changed from an amorphous form to a neddle and plate-like crystal form with more pores. On the other hand, the high flow rate of ammonium hydroxide solution gave less agglomeration. When acetic acid or propionic acid was added as an additive, the filtered cake looked like jelly which contained much water. When the filtered cake was washed with acetone-toluene-acetone, a great improvement in the drying rate and the softness of filtered cake was obtained.

이량체형성의 이성분계 단백질의 막분리에 관한 연구

鄭貴榮,李章旭 弘益大學校 科學技術硏究所 1996 科學技術硏究論文集 Vol.7 No.1

Separation of protein mixtures of ovalbumin(ALB) and myoglobin(MYO) with a membrane adsorber was studied. The mathematical model including axial diffusion, adsorption kinetics, and dimerization of albumin predicted breakthrough curves. Additionally, effects of kinetic parameters on the behavior of breakthrough curves were studied. The rate constant of dimerization of ovalbumin has strong effects on the behavior of breakthrough curve.

Fluidized Bed 낸 CVI에 대한 수치모사의 이론적 연구

鄭貴榮,金容鐸 弘益大學校 科學技術硏究所 2001 科學技術硏究論文集 Vol.12 No.-

In this research, the mathematical modeling of the formation of SiC layer on the activated carbon was studied to improve the durability and oxidation resistance of catalyst supports. SiC layer on the activated carbon was formed by permeating SiC from trimethylchlorosilane(MTS) into pores and depositing while the porous structure was kept. Changes of the amount of deposition, the pore diameter, the surface area with time were obtained by simulating reaction in an isothermal reactor. The uniform deposition in the pores of samples was obtained at a lower concentration of the reactant and a lower pressure. Additionally, it was observed that the pore diameter and the surface area have points of inflection at certain times of deposition, because deposition occurred on the inside surface of the pore at first and then on the outside surface of the particle.

모멘트법에 의한 고분자 열분해 연구

鄭貴榮 弘益大學校 科學技術硏究所 1997 科學技術硏究論文集 Vol.8 No.-

Moment method was applied to the thermal degradation of polymer. There are random degradation and specific degradation of polymer. In this research, thermal degradation at 275 ℃ of polystyrene in mineral oil was studied. The evolution in time of polymer molecular weight distributions was monitored by gel permeation chromatography of polymer taken from the reactor. Gamma function was fitted to the experimental data of the molecular weight distributions after the random degradation of PS. Average molecular weight and variance were obtained as a function of time. Random degradation rate constant of polystyrene was estimated from these data. The degradation rate constant decreased with the averge molecular weight of the polymer.

단위 연료전지 내 가스채널에서의 Phoenics를 이용한 수치모사 연구

劉旼炡,鄭貴榮 弘益大學校 科學技術硏究所 2005 科學技術硏究論文集 Vol.16 No.-

The mathematical modeling of MCFC was carried out to observe the effects of the water-gas shift reaction. Using the commercial CFD program Phoenics, studies on the butterfly-type fuel cell was carried out. Calculated results were compared with those of the general type fuel cell. In previous studies, it was assumed that properties of gases along the direction of gas channel height were constant. The consumption and the generation rates of CO_(2) could be decided as the rates which gave 0.4 of the hydrogen utilization in the anode gas channel. The y-directional average values were similar to the values near the separator surface and they positioned near the electrode surface. Therefore it was shown that it is safe to assume that the gas concentration along the direction of gas channel height is constant. Effects of the size of channel height on the x-directional distribution of X_(a)co_(2) appeared greater at a constant linear velocity rather than at a constant volumetric flow rate. As expected, the x-directional distributions of Xco_(2) in the butterfly type gas channels became more uniform.

용융탄산염 연료전지의 CFD를 이용한 수치모사

劉旼炡,鄭貴榮 弘益大學校 科學技術硏究所 2004 科學技術硏究論文集 Vol.15 No.-

The gas channels of the molten carbonate fuel cell (MCFC) have been studied numerically. Distributions of pressure and gas compositions in the anode and the cathode gas channels were observed. The rate constant of the electrochemical reaction was deduced with the value of hydrogen usage. Calculations were made at the different values of the reaction rate constant and also at different sizes of gas channels. The commercial fluid dynamics program, Phoenics, was used. When the volumetric velocity is constant and the height of gas channel is changed, the changes of the CO2 concentration are big when the height of gas channel is thick. When the volumetric velocity is constant and the rates of generation and consumption are multiplied by 0.5, 1 and 2, the changes of the CO2 concentration are big when the rate of generation and consumption is big. On the other hand, when the linear velocity is constant, the changes of the CO2 concentration are big when the height of gas channel is thin.

단백질 막분리에 대한 수치모사를 이용한 변수의 영향 연구

李章旭,鄭貴榮 弘益大學校 科學技術硏究所 1995 科學技術硏究論文集 Vol.6 No.-

The mathematical modeling for the system which separates ALA-BSA protein mixtures using the anion-exchange membrane, was studied. By fitting theoretical values to the experimental data in the reference, values of system parameters were obtained. The ligand capacity, the adsorption rate constant, and the desorption rate constant of ALA were 30kg/㎥, 0.048㎥/kg·sec, and 0.035 sec?, respectively. Additionally, those of BSA were 36kg/㎥, 0.36㎥/kg·sec, and 0.0001 sec?, respectively. The effects of system parameters such as ligand capacity(q?), adsorption rate constant (k?) and desorption rate constant(k?) on the break-through curves were studied. Changes of adsorption and desorption rate constants of ALA, which binds weakly to the ligand, have more effects on the protein seperation than those of BSA which binds strongly to the ligand.

Preparation of High-Surface-Area Catalysts Supports Coated with SiC by CVI

Gui-Yung Chung,Young-Joon Kim,Hee Kim 한국공업화학회 2004 Journal of Industrial and Engineering Chemistry Vol.10 No.4