| 1. |
- Fontes, Eduardo, et al.
(författare)
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A heterogeneous model for the MCFC cathode
- 1995
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Ingår i: Electrochimica Acta. - 0013-4686. ; 40:11, s. 1641-1651
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Tidskriftsartikel (refereegranskat)abstract
- A steady state agglomerate model for the MCFC cathode which takes into account the heterogeneous structure of this porous electrode is presented. The resulting model equations are solved by means of the finite element method. Calculations have been performed on two different test structures and include the influence of kinetics, porosity, outer surface area and distribution of electrolyte film. Comparisons with the filmed agglomerate model show that it is possible to obtain excellent agreement between the polarisation curves predicted by the two different models if a uniform film is used in the simulations. The tortuosity in the filmed agglomerate model is used as a fitting parameter. Other effects that evolve in the heterogeneous model due to variations in the local structure are not revealed in the pseudohomogeneous model. The effect of a non-uniform electrolyte film thickness was investigated by solving the problem for a structure with pore mouths filled by an electrolyte meniscus. Also the effect of an electrolyte meniscus between spherical agglomerates was investigated.
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| 2. |
- Fontes, Eduardo, et al.
(författare)
-
Effects of different design parameters on the performance of MCFC cathodes
- 1996
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Ingår i: Electrochimica Acta. - 0013-4686. ; 41:1, s. 1-13
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Tidskriftsartikel (refereegranskat)abstract
- The effects of electrode thickness, electrolyte filling and current collector geometry on the performance of MCFC cathodes are investigated by using a steady state mathematical model. A two-dimensional pseudo-homogeneous model for the three-phase system in the cathode is used, which includes the polarisation curves from the heterogeneous agglomerate model[1] as local source functions. The model takes into account the potential distribution in the electrolyte and catalyst phase but neglects mass transport limitations in the gas phase. The simulations show that, for cathodes with a finite electronic conductivity, there is a substantial potential distribution perpendicular to the depth of the electrode depending on the size of the gas holes in the current collector.
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| 3. |
- Fontes, Magnus
(författare)
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Parabolic equations with low regularity
- 1996
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this work we study a variational method for treating parabolic equations that yields new results for non-linear equations with low regularity on source and boundary data. We treat mainly strongly parabolic quasilinear equations and systems in divergence form. The basic idea is to compose the parabolic operator with a weighted sum of the identity operator and the Hilbert transformation in the time direction, and in this way obtain a coercive operator. We work with functions having space derivatives in some Lp-space and half order time derivatives in L2. A key to our results is the celebrated theorem by Marcel Riesz concerning the boundedness of the Hilbert transformation on Lp-spaces when p is strictly greater than one.
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