| dc.description.abstract | This study investigates experimentally the flow distributions of internal manifolds in multi-stacks for planar solid oxide fuel cells (SOFC). The main goal is to evaluate the validity of a numerical and analytical model proposed by Kee et al. (2002) for the Z-type rib-channel stack design of planar SOFC, where the Z-type indicates that the flow directions of the distributed flows flowing through both the feed header and the exhaust header are the same. A hydraulic platform using the laser-induced fluorescence (LIF) visualization is established to obtain the flow distributions in multi-stacks including six layers, each layer having a number of rib-channels varying from 10 to 50. The obtained rib-channel flow images in each layer are binarized to calculate corresponding velocities using a MATLAB-based software and thus flow non-uniformity in each layer with many rib-channels can be estimated. Concerning the Kee＇s model, the flow was assumed to be laminar steady and incompressible, but with consideration of the hydrostatic pressure due to different elevations. Based on the continuity and momentum equations, a non-dimensional parameter, NcWlGl=constant, was proposed (Kee＇s model), where Nc is the number of channel, Wl is the non-dimensional mass flow rate due to the pressure drop, and Gl is the non-dimensional viscous drag term. The non-uniformity was defined as the difference between the maximum and minimum mass flow rate divided by the maximum mass flow rate. There are eight cases with different values of NcWlGl in Kee＇s model, because of the rib-channel manufacturing limitation, we can only measure three cases having NcWlGl=0.81, 5.23 and 8.11 to test the validity of the Kee＇s model. First, a series of experimentals are carried out for the case of NcWlGl=0.81 using only one single layer but with three different numbers of rib-channels, where Nc=10, 25 and 50. The results show that suggesting the velocity distribution data among these three different values of Nc are very similar, that the Kee＇s model may be used even when numbers of rib-channels are different. For the study of multi-stacks, we set NcWlGl=5.23 and 8.11, each having six layers, and each layer having 10 rib-channels. It is found that the measured flow distribution data are close to the predication of Kee＇s model, showing the same trend for the experimental and modeling results. However, more mass flow rates are found for the lower layer because of the gravity effect. Most previous results were obtained from numerical and analytical studies. The present study is probably the first experimental simulation of the Kee＇s model and these results should be useful to the flow distribution design of multi-stacks for planar SOFC.
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