• 한국전기전자재료학회논문지
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• 제24권5호
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• pp.351-354
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• 2011

This paper was carried about thermal analysis for high efficiency point contact solar cell. Therefore, we carried about 2-D device and process simulator according to design and process parameters. As a result of simulations, power transfer efficiency have decreased more increasing temperature. Especially, power transfer efficiency of room temperature have been showed 25%. The other hand, power transfer efficiency of 350 K kalvin temperature have been showed 20%. Therefore, we will considered design with thermal dissipation of device.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.1142-1143
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• 2008

As well known, the maximum power point tracking (MPPT) is an important role in photovoltaic (PV) power systems. MPPT finds and maintains the operation of PV at the maximum power point when the irradiation and cell-temperature change. In this paper, the studied system includes a PV array, a Buck-Boost DC/DC converter, a DC/AC inverter and it is connected to the three phase power system. The solar array operates as a non-linear voltage source. The P&O algorithm with power feed-back is used to control the operating point of PV array at the maximum power point. The effects of irradiation and cell-temperature on the dynamic responses are also considered.

• Journal of Mechanical Science and Technology
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• 제20권3호
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• pp.391-398
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• 2006

This work involves a method for modeling the flow distribution in the stack of a solid oxide fuel cell. Towards this end, a three dimensional modeling of the flow through a Solid Oxide Fuel Cell (SOFC) stack was carried out using the CFD analysis. This paper examines the efficacy of using cold flow analysis to describe the flow through a SOFC stack. It brings out the relative importance of temperature effect and the mass transfer effect on the SOFC manifold design. Another feature of this study is to utilize statistical tools to ascertain the extent of uniform flow through a stack. The results showed that the cold flow analysis of flow through SOFC might not lead to correct manifold designs. The results of the numerical calculations also indicated that the mass transfer across membrane was essential to correctly describe the cathode flow, while only temperature effects were sufficient to describe the anode flow in a SOFC.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2015년도 전력전자학술대회 논문집
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• pp.373-374
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• 2015

This paper proposes a dynamic thermo-electric model that links electrical parameters with thermal parameters. In this model, the irradiance and ambient temperature are used to calculate the cell temperature based on a four-layer model that includes the PV cell and surround materials. The calculated cell temperature is then used in the electrical model to accurately adjust the PV electrical characteristics. Dynamic PV characteristics, parallel capacitive and series inductive components, are added to the conventional single-diode model. The results show the effectiveness of this model rather than other conventional models of a PV panel.

• 한국환경과학회지
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• 제23권6호
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• pp.1003-1012
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• 2014

We examined the combined impacts of future increases of $CO_2$ and temperature on the growth of four marine diatoms (Skeletonema costatum, Chaetoceros debilis, Chaetoceros didymus, Thalassiosira nordenskioeldii). The four strains were incubated under four different conditions: present ($pCO_2$: 400ppm, temperature: $20^{\circ}C$), acidification ($pCO_2$: 1000ppm, temperature: $20^{\circ}C$), global warming ($pCO_2$: 400ppm, temperature: $25^{\circ}C$), and greenhouse ($pCO_2$: 1000ppm, temperature: $25^{\circ}C$) conditions. Under the condition of higher temperatures, growth of S. costatum was suppressed, while C. debilis showed enhanced growth. Both C. didymus and T. nodenskioldii showed similar growth rates under current and elevated temperature. None of the four species appeared affected in their cell growth by elevated $CO_2$ concentrations. Chetoceros spp. showed increase of pH per unit fluorescence under elevated $CO_2$ concentrations, but no difference in pH from that under current conditions was observed for either S. costatum or T. nodenskioeldii, implying that Chetoceros spp. can take up more $CO_2$ per cell than the other two diatoms. Our results of cell growth and pH change per unit fluorescence suggest that both C. debilis and C. didymus are better adapted to future oceanic conditions of rising water temperature and $CO_2$ than are S. costatum and T. nodenskioeldii.

• 한국세라믹학회지
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• 제53권5호
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• pp.506-510
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• 2016

The eutectic melt of BaO-CuO flux is known to be a potential sintering aid for $Ba(Zr,Y)O_3$ (BZY) electrolyte for proton-conducting ceramic fuel cells (PCFCs). A density of BZY higher than 97% of theoretical density can be achieved via sintering at $1300^{\circ}C$ for 2 h using a flux composed of 28 mol% BaO and 72 mol% CuO. In the present study, chemical and structural evolution of BaO-CuO flux throughout the sintering process was investigated. An intermediate holding step at $1100^{\circ}C$ leads to formation of various impurity compounds such as $BaCuO_{1.977}$, $Ba_{0.92}Cu_{1.06}O_{2.28}$ and $Cu_{16}O_{14.15}$, which exhibit significantly larger unit cell volumes than the matrix. The presence of such secondary compounds with large lattice mismatch can potentially lead to mechanical failure. On the other hand, direct heating to the final sintering temperature produced CuO and $Cu_2O$ as secondary phases, whose unit cell volumes are close to that of the matrix. Therefore, the final composition of the flux is strongly affected by the thermal history, and a proper sintering schedule should be used to obtain the desired properties of the final product.

• 멤브레인
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• 제21권1호
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• pp.30-38
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• 2011

고온 무가습 조건에서 고분자 전해질 막의 수화성 및 수소이온 전도도 향상을 위해 sulfonated poly(aryl ether sulfone) 전해질 고분자에 sulfated $ZrO_2$ ($s-ZrO_2$)를 함침시킨 유-무기 복합막을 제조하였다. X-ray diffraction를 통해 $s-ZrO_2$ 의 구조적 특징과 입자크기를 확인하였으며 추가적으로 FT-IR 분석을 통해, $s-ZrO_2$입자에 술폰산기가 화학적으로 결합되어 있음을 확인 할 수 있었다. 다양한 $s-ZrO_2$ 조성비를 가진 유-무기 복합막의 이점을 확인하기 위해서 이온교환능력, 함수율, 수소이온 전도도를 측정하였다. 실험결과, $s-ZrO_2$의 조성비를 달리한 유-무기 복합막의 수소이온 전도도는, 5 wt% $s-ZrO_2$를 함유한 유-무기 복합막의 경우에서, 상온 수화조건 뿐만 아니라 $100^{\circ}C$ 이상의 무가습 조건에서 매우 높은 수소 이온 전도도를 나타내었다. 특히 $120^{\circ}C$ 무가습 조건에서도 5 wt% $s-ZrO_2$를 함유한 유-무기 복합막이 $0.0018\;S\;cm^{-1}$의 매우 높은 전도도를 나타냄으로써 $100^{\circ}C$ 이상의 고온에서도 높은 수화도를 유지하는 유-무기 복합막의 제조가 가능하였다.

• 전기학회논문지P
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• 제58권4호
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• pp.563-567
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• 2009

The polymer electrolyte membrane fuel cell(PEMFC) with the advantages of low-operating temperature, high current density, low cost and volume, fast start-up ability, and suitability for discontinuous operation becomes the most reasonable and attractive power system for transportation vehicle and micro-grid power plant in a household. 200W PEM-type FCs system was integrated by this study, then the electrical characteristics and diagnosis of the fuel cell were analyzed with variations on mass flow rate and stack temperature. The ranges of the variations are 1~8L/min on $H_2$ volume and $20{\sim}70^{\circ}C$ on stack temperature.

• 한국수소및신에너지학회논문집
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• 제15권1호
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• pp.54-61
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• 2004

Temperature characteristics in a stack of molten carbonate fuel cell (MCFC) have been investigated with simulation based on the computational fluid dynamics (CFD) codes and experimental way. The MCFC has generally two stack structures when the natural gas is used as fuel; one is the external reforming type and the other is internal reforming type. Computer simulation at the external reforming stack suggests that the maximum temperature in the stack depends on the gas flow length. The 2 kW MCFC stack with 25 cm gas flow length showed about $675^\circ{C}$ of maximum temperature.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2001년도 유체기계 연구개발 발표회 논문집
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• pp.419-424
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• 2001

TCV(Temperature control valve by pressure compensation) controls temperature constantly, when it is sending steam or high temperature water to heating device of heat exchanger. For designing TCV, the ratio of piston and hole diameters is one of the important design parameters. Numerical analysis is carried out to elucidate the flow characteristics in the TCV with different port areas of cold and hot waters, using the k-$\epsilon$ turbulence model and Cartesian cut-cell method. Numerical results show that the exit flow rate is mainly affected by pressure distribution in the piston.