| Summary: | 碩士 === 國立中央大學 === 能源工程研究所 === 96 === This thesis investigates experimentally flow distributions in a planar SOFC short-stack using various designs of external manifolds and thus increases flow uniformity of the short-stack. A hydraulic platform combined with laser-induced fluorescence (LIF) and dye visualization (DV) techniques are established to obtain flow fields in the short-stack including three layers, each layer having 12 rib-channels. A Matlab-based code is used to process these flow field images by the binary method and thus corresponding velocities in each of 12 channels for all three different layers can be extracted. Results from both LIF and DV methods are roughly the same with the largest difference up to 10 %, when the channel Reynolds number(Re = VDh/???are within 25~100, where V is the velocity, Dh is the hydraulic diameter of the rib channel, and ? is the kinematic viscosity of fluid. The focus is placed on the effect of different flow directions in both the feed header (FH) and the exhaust header (EH) to flow uniformity of the short-stack. There are five arrangements: (1) The Conventional-type, where both FH and EH are in the same streamwise direction of flow channels; (2) Z-type, where FH and EH are in the same spanwise direction of flow channels; (3) TZ-type, both FH and EH in the same transverse direction of flow channels; (4) U-type, similar to (2) but FH and EH are in opposite directions; (5) TU-type, similar to (3) but FH and EH are in opposite directions. These experimental results show that the fourth design (U-type) has the best flow uniformity among all different designs. In attempt to further improve flow uniformity of the U-type design, a triangular pyramid is placed in the feed header, which can further increase flow uniformity in each layer of the short-stack. Based on the best knowledge of the author, the present study is the first experimental measurement on the flow distributions in the short-stack of planar SOFC and should be useful for numerical simulations.
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