This paper conducts a multiscale parametric study of temperature and composition effects on the transport phenomenon of a solid oxide fuel cell (SOFC). The molecular dynamics technique was employed to study the transport phenomenon of the solid electrolyte, which is made of yttria-stabilized zirconia. The influences of Y2O3 concentration and various operation temperatures on the SOFC were studied. Simulation results show that there exists an optimal concentration of 8mol% of Y2O3 in the composition for oxygen transport. Also higher operation temperature promotes the oxygen ion-hopping process that increases the ionic conductivity. A macroscale parametric study was also conducted in this paper to validate the influence of the temperature uniformity in the solid electrolyte by employing the computational fluid dynamics technique. The temperature distribution maps of a single-cell planar SOFC with coflow, counterflow and cross-flow channel designs are presented. The results conclude that the coflow configuration is the best design of the three.

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A mass transfer model with single pass flow is proposed for evaluating the performance characteristics of a combined system composed of a dialyzer for hemodialysis (HD) and a coated adsorbent packed cartridge for hemoperfusion (HP). In the dialyzer, the mass transfer equation is represented in terms of three dimensionless parameters, i.e., extraction ratio, number of transfer unit, and ratio of flow rates. For the hemoperfusion cartridge, the model equations are derived by formulating the following four processes: convective mass transfer in the bed, fluid phase mass transfer around a coated adsorbent particle, transport across a film of coated membrane, and diffusion within an adsorbent particle. The Freundlich isotherm model is used for the adsorption on adsorbent particles. Applications of the mathematical model to systems to be potentially used in clinical practice are discussed. Solutions for two different sequences of arrangement, i.e., HD‐HP and HP‐HD, are obtained and discussed in terms of their performance efficacies. Theoretical results demonstrate that the HD‐HP arrangement will give better performance in most clinical encounters.

This paper analyzes the transport phenomenon of a solid oxide fuel cell (SOFC) from micro and macro aspects. The micro-scale model focuses on the ion hopping transportation inside the solid electrolyte and the macro-scale model aims at the flow phenomenon and thermal management inside the diffusion layers and the flow channel. In SOFCs, oxygen ions are conducted through the ceramic membrane of Yttria-Stablized Ziconia (YSZ), which is composed of ZrO2 and Y2O3. This paper uses molecular dynamics (MD) method to evaluate the ion conductivity of the solid electrolyte. Doping with different percentage of Y2O3, the ion hopping simulation shows that about 8 mole % gives the optimal performance. Also the higher the operation temperature, the better the ion conduction. Temperature field management is also a critical issue in the SOFC design. A set of three-dimensional computational fluid dynamics (CFD) model (including mass, momentum, energy and concentration equations) inside the porous diffusion layers and the flow channel of the SOFC were employed to estimate the cooling effect under different pattern of flow channel designs. All simulation results were validated with experiments reported from other literatures. The integration of the micro and macro-scale analyses proves to be versatile in the SOFC prototype design.