http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
박막을 형성한 원통형 덩어리 모델의 다공성 기체확산 전극 유효성인자
노제승,홍성안,서성섭 ( Je Seung Roh,Seong Ahn Hong,Sung Sup Suh ) 한국화학공학회 1996 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.34 No.5
The porous gas diffusion electrode was described by cylindrical agglomerate model with electrolyte thin film to investigate the effectiveness factor. System variables such as reaction rate constant, diffusion coefficients, conductivity, agglomerate size, electrode thickness and temperature were combined into four dimensionless parameters. The effectiveness factor was slightly larger than that for slab agglomerate model. However, the effects of the system variables on the effectiveness factor were similar. The effect of electrolyte thin film was very small where the ratio of the thin film thickness to the agglomerate size was less than 0.01. The electrode thickness for the optimum electrode performance was independent of the agglomerate shape.
윤성필,한종희,남석우,임태훈,홍성안,현상훈,유영성,Yoon Sung Pil,Han Jonghee,Nam Suk Woo,Lim Tae-Hoon,Hong Seong-Ahn,Hyun Sang-Hoon,Yoo Young-Sung 한국전기화학회 2001 한국전기화학회지 Vol.4 No.2
기체/전해질/LSM $(La_{0.85}Sr_{0.15}MnO_3)$ 공기극이 만나는 삼상계면 (triple phase boundary) 주위에 YSZ ($8mol\%$ yttria stabilized zirconia) 코팅막 (coating film) 을 형성하여 추가로 삼상계면을 크게 늘린 새로운 전극 미세구조를 갖는 복합 공기극 (composite cathode) 을 개발하였다. 이 복합 공기극을 전해질 두께가 약 $30{\mu}m$인 연료극 (anode)v 지지체 위에 형성하여 $700\~800{\circ}C$의 온도에서 전류전압 특성 및 교류 임피던스 분석을 실시하였다. $800^{\circ}$, 공기 및 수소 조건에서 교류 임피던스 분석 결과 1000Hz주파수 영역을 대변하는 저항성분 R1은 연료극 분극 저항에 해당하였고 100Hz주파수 영역의 저항성분 R2는 공기극 분극 저항 성분, 그리고 10Hz이하 영역의 저항성분 R3는 전극을 통한 기체확산 저항성분으로 특히, 작동 조건인 공기 및 수소 분위기에서는 연료극 쪽 반응기체에 의한 기체확산 저항 성분임을 알 수 있었다. 전지성능 측정 결과 이 복합 공기극을 장착한 전지는 $800^{\circ}C$, 공기 및 산소 조건에서 각각 $0.55W/cm^2$ $1W/cm^2$의 높은 전지성능을 나타내었다. 전류전압 곡선은 기울기가 다른 두 구간으로 구분되었으며, 낮은 전류밀도 하에서 보이는 급격한 전압감소 구간은 공기극 분극저항이 주된 성능 저하의 원인인 반면, 높은 전류밀도 하에서 나타나는 완만한 전압 감소 구간은 전해질에 관련된 분극저항이 주된 성능 저하의 원인이었다. YSZ ($8mol\%$ yttria-stabilized zirconia)-modified LSM $(La_{0.85}Sr_{0.15}MnO_3)$ composite cathodes were fabricated by formation of YSZ film on triple phase boundary (TPB) of LSM/YSZ/gas. The YSZ coating film greatly enlarged electrochemical reaction sites from the increase of additional TPB. The composite cathode was formed on thin YSZ electrolyte (about 30 Um thickness) supported on an anode and then I-V characterization and AC impedance analyses were performed at temperature between $700^{\circ}C\;and\;800^{\circ}C$. As results of the impedance analysis on the cell at $800^{\circ}C$ with humidified hydrogen as the fuel and air as the oxidant, R1 around the frequency of 1000 Hz represents the anode Polarization. R2 around the frequency of 100Hz indicates the cathode polarization, and R3 below the frequency of 10 Hz is the resistance of gas phase diffusion through the anode. The cell with the composite cathode produced power density of $0.55\;W/cm^2\;and\;1W/cm^2$ at air and oxygen atmosphere, respectively. The I-V curve could be divided into two parts showing distinctive behavior. At low current density region (part I) the performance decreased steeply and at high current density region (part II) the performance decreased gradually. At the part I the performance decrease was especially resulted from the large cathode polarization, while at the part H the performance decrease related to the electrolyte polarization.
세리아가 첨가된 니켈/칼슘 하이드록시 아파타이트 촉매 상의 부탄 부분산화 연구
곽정훈(Kwak, Jung-Hun),이상엽(Lee, Sang-Yup),김미소(Kim, Mi-So),남석우(Nam, Suk-Woo),임태훈(Lim, Tae-Hoon),홍성안(Hong, Seong-Ahn),윤기준(Yoon, Ki-June) 한국신재생에너지학회 2007 한국신재생에너지학회 학술대회논문집 Vol.2007 No.11
Partail oxidation(POX) of n-butane was investigated in this research by employing ceria-promoted Ni/calcium hydroxyapatite catalysts (Ce_xNi_{2.5}Ca_{10}(OH)₂(PO₄)<sub>6</sub> ; x = 0.1{sim}0.3) which had recently been reported to exhibit good catalytic performance in POX of methane and propane. The experiments were carried out with changing ceria content, O₂/n-C₄H_{10} ratio and temperature. As the O₂/n-C₄H_{10} feed ratio increased up to 2.75, n-C₄H_{10} conversion and H₂ yield increased and the selectivity of methane and other hydrocarbons decreased. But with O₂/n-C₄H_{10} = 3.0, n-C₄H_{10} conversion and H₂ yield decreased. This is considered due to that too much oxygen may inhibit the reduction of Ni or induce the oxidation of Ni, which results in poor catalytic activity. The optimum O₂/n-C₄H_{10} ratio lay between 2.50 and 2.75. Ce_{0.1}Ni_{2.5}Ca_{10}(OH)₂(PO₄)<sub>6</sub> showed the highest n-C₄H_{10} conversion and H-2 yield on the whole. In durability tests, higher hydrogen yield and better catalyst stability were obtained with the O₂/n-C₄H_{10} ratio of 2.75 than with the ratio of 2.5.
Methane-Air 혼합 Gas에서 구동하는 하니컴 형태의 SC-SOFC
박병탁(Park, Byung-Tak),윤성필(Yoon, Sung Pil),김현재(Kim, Hyun Jae),남석우(Nam, Suk Woo),한종희(Han, Jonghee),임태훈(Lim, Tae-Hoon),홍성안(Hong, Seong-Ahn),이덕열(Lee, Dokyol) 한국신재생에너지학회 2005 한국신재생에너지학회 학술대회논문집 Vol.2005 No.06
One of the most critical issues in sol id oxide fuel cell (SOFC)running on hydrocarbon fuels is the risk of carbon formation from the fuel gas. The simple method to reduce the risk of carbon formation from the reactions is to add steam to the fuel stream, leading to the carbon gasification react ion. However, the addition of steam to fuel is not appropriate for the auxiliary power unit (APU) and potable power generation (PPG) systems due to an increase of complexity and bulkiness. In this regard, many researchers have focused on so-called 'direct methane' operation of SOFC, which works with dry methane without coking. However, coking can be suppressed only by the operation with a high current density, which may be a drawback especially for the APU and PPG systems. The single chamber fuel cell (SC-SOFC) is a novel simplification of the conventional SOFC into which a premixed fuel/air mixture is introduced. It relies on the selectivity of the anode and cathode catalysts to generate a chemical potential gradient across the cell. Moreover it allows compact and seal-free stack design. In this study, we fabricated honeycomb type mixed-gas fuel cell (MGFC) which has advantages of stacking to the axial direction and increasing volume power density. Honeycomb-structured SOFC with four channels was prepared by dry pressing method. Two alternative channels were coated with electrolyte and cathode slurry in order to make cathodic reaction sites. We will discuss that the anode supported honeycomb type cell running on mixed gas condition.
기준 전극을 이용한 용융탄산염 연료전지의 분극 특성 해석
한종희,이갑수,정창열,윤성필,남석우,임태훈,홍성안,Han Jonghee,Lee Kab Soo,Chung Chang-Yeol,Yoon Sung-Pil,Nam Suk-Woo,Lim Tae-Hoon,Hong Seong-Ahn 한국전기화학회 2001 한국전기화학회지 Vol.4 No.3
용융탄산염 연료전지의 장기 운전시 각 전극별 분극의 변화를 Au, $CO_2/O_2$ 기준전극이 부착된 단위전지를 이용하여 성공적으로 해석하였다. 서로 다른 구성요소로 조합된 네 가지 단위 전지를 운전하며 각 전극의 분극을 해석한 결과, 이미 알려진 바와 같이 공기극의 분극 크기가 연료극의 경우보다 큰 것을 실험적으로 측정할 수 있었다. 고온 부식 방지를 위해 cell frame의 wet seal부분에 Al코팅을 한 전지는 6,000시간까지 성능을 유지하여 부식이 전지 성능 저하에 큰 역할을 하고 있음을 알 수 있었다. 한편, $LiCoO_2$가 코팅된 안정화 공기극은 일반적으로 사용되는 NiO 공기극보다 lithiation에 필요한 시간이 길어 운전 초기에 공기극 분극이 크고 성능이 낮았으나 지속적인 운전으로 공기극이 충분히 lithiation되면서 공기극의 분극이 작아지고 성능도 점차 증가하였다. $Li_2CO_3/Na_2CO_3$ 전해질을 사용한 전지는 운전 중 성능이 하락과 상승을 반복하는 진동현상을 보였는데 이는 연료극보다는 공기극의 영향으로 해석되었다. 대부분의 단위전지들이 급격한 성능 하락을 보였을 경우의 공기극 분극은 급격히 증가하였으며 이로써 용융탄산염 연료전지의 수명 향상을 위해서는 공기극의 개선이 필수적이라는 것을 알 수 있었다. A long-term variation of electrode polarization in the MCFC has been analyzed successfully using a single cell with a Au, $CO_2/O_2$ reference electrode Four different cells with different components were operated and their electrode polarizations were analyzed. As published in the literatures, the cathode polarization was larger than that of the anode. The more stable operation of a single cell with the Al-coated cell frame up to 6,000hrs indicates that the corrosion at the cell frame, particularly wet seal area, plays an important role to determine the lifetime of a MCFC. At the initial stage of the cell operation, the voltage of the cell using a cathode stabilized by the $LiCoO_2$ coating was relatively low due to the high cathode polarization. As the cell was operated and the stabilized cathode was lithiated sufficiently, the cathode polarization decreased and the cell voltage was recovered. It was observed that the voltage of the cell using the $Li_2CO_3/Na_2CO_3$ electrolyte fluctuated with operation time and the cathode polarization fluctuated along with the cell voltage quite similarly. Although the mechanisms of the voltage fluctuation were not clear yet, the results imply that the voltage fluctuation was related with a reaction in the cathode side. After testing every single cell, the cathode polarization increased with the steep decrease in the cell voltage. Thus, the cathode should be improved in order to develop more durable MCFC.