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Assessment on hermetic property and mechanical compatibility of various groove-gasket sealing designs for solid oxide fuel cell stack
(2012-09-01)
Punbusayakul, N.
;
Boonsiri, K.
;
Charojrochkul, S.
;
Fungtammasan, B.
;
Charoensuk, J.
Assessment among various groove-gasket designs under solid oxide fuel cell operating condition is presented. The gasket is deformable under the stress applied by external loading between 0.13-0.67 MPa. The operating temperature is from 30 to 800 °C. It has an indicated width of 1.95 mm and depth of 2.1 mm., which is accommodated in a square, triangular and U groove channel having the dimension of 2.0 × 2.0 mm 2. From the results, the U shape configuration provides the best performance with immeasurable leak rate under the applying load represented in term of global stress of 0.67 MPa. A stress analysis using Finite Element Method (FEM) tool, ABAQUS™, suggests sufficiently high compressive stress far exceeding the elastic limit with enough coverage of such high-stress area for U-shape design. In contrast, those from square and triangular designs posses relatively lower well-distributed stress and smaller region of highly concentrated stress, respectively. The associated deformed cross section suggests that the gasket has plastically deformed toward the U-shape wall surface at a greater degree than those for triangular-shape design. It can be concluded that the greater region in deformed gasket surface can more effectively reduce interconnectivity of micro channel on the interface between the gasket and the interconnector surfaces. © 2012 Elsevier B.V. All rights reserved.
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Improved electrical conducting wires for SOFCs
(2008-01-01)
Masomtob, M.
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Wongtida, K.
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Charoensuk, J.
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Charojrochkul, S.
Solid Oxide Fuel Cells (SOFCs) have attracted a number of researchers due to their efficiency as alternative energy devices. Studies have been conducted to investigate different components of the SOFCs to improve the performances. Current collecting wires are the components which have affected the overall performance. Since SOFCs are normally operated in the temperature range of 700-1000 °C in dual atmospheres, the wiring material must be able to function at this condition. Currently, the material used to make the wires is platinum because of its high electrical conductivity, high melting point and oxidation resistant. However, platinum is expensive, especially for the practical operation of SOFCs. Silver could be an alternative choice due to its very high electrical conductivity. Nevertheless, the melting point of silver is rather low (900-960 °C). In our study, a modified silver current collecting wire has been used in the temperature range of 100-1000 °C. Their conductivity curves have demonstrated higher performances in comparison with the systems employing Pt and gold wires. In addition, the cost is reduced approximately 800-1000 times from that of the traditional material used. © 2008 Trans Tech Publications, Switzerland.
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Behaviour of various glass seal for planar solid oxide fuel cell
(2008-01-01)
Punbusayakul, N.
;
Wongklang, W.
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Wongtida, K.
;
Charoensuk, J.
;
Charojrochkul, S.
One of the critical issues in designing a planar solid oxide fuel cell (SOFC) is the development of materials to hermetically seal the metal (430 series stainless steel) or ceramic interconnector with the ceramic electrolyte of the cell. The main objective of this sealing material is to achieve a low leak rate, long-term stability at operating temperature and chemical compatibility with other components. One of the compositions has been operated in an SOFC in excess of 30 minutes over the range of 600, 700, 800, and 900°C. The seal is a composition of polymer blend and glass of 1:3, 1:1 and 3:1 by weight. The leakage rate of each seal was measured simultaneously under the compressive force of 100 N, 2 bar Helium. The seal was characterized using a thermogravimetric analysis. The effect of glass composition on operating temperature and compressive forces on the leakage rate have been discussed and correlated. © 2008 Trans Tech Publications, Switzerland.
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Performance of ethanol-fuelled solid oxide fuel cells: Proton and oxygen ion conductors
(2007-09-15)
Jamsak, W.
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Assabumrungrat, S.
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Douglas, P. L.
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Laosiripojana, N.
;
Suwanwarangkul, R.
This paper investigates the performance of ethanol-fuelled solid oxide fuel cells (SOFCs) with two types of solid electrolytes, namely oxygen ion-conducting (SOFC-O2-) and proton-conducting electrolytes (SOFC-H+). Our previous work reported that the SOFC-H+ shows superior theoretical performance over the SOFC-O2- electrolyte. However, in this work when all resistances are taken into account, the actual performance of the SOFC-O2- (Ni-YSZ|YSZ|YSZ-LSM) becomes significantly better than that of SOFC-H+ (Pt|SCY|Pt). The maximum power density of the SOFC-O2- is about 34 times higher than that of the SOFC-H+ when operated at an inlet H<inf>2</inf>O:EtOH ratio of 3, a fuel utilization factor of 80% and a temperature of 1200 K. Then the required values of the total resistance of the SOFC-H+ to achieve the same power density as the SOFC-O2- were determined. It was found that due to the superior theoretical performance of the SOFC-H+, it is not necessary to reduce the SOFC-H+ total resistance to the same values as the one for SOFC-O2-. The study also indicates that reduction of only the electrolyte resistance is not sufficient to improve the SOFC-H+ performance and, therefore, the other resistances including activation, electrodes and interconnect resistances need to be reduced simultaneously. Finally, the improvement of the electrolyte resistance by changing its resistivity and thickness is discussed. © 2007 Elsevier B.V. All rights reserved.

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