實驗量測分析Kee’s燃料電池堆流場分佈模式之可靠度; Experimental Analysis of Kee’s Flow Distribution Model for Planar Solid Oxide Fuel Cell Stacks

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题名:	實驗量測分析Kee’s燃料電池堆流場分佈模式之可靠度;Experimental Analysis of Kee’s Flow Distribution Model for Planar Solid Oxide Fuel Cell Stacks
作者:	蔡文哲;Wen-che Tsai
贡献者:	能源工程研究所
关键词:	燃料電池堆內歧管;Kee＇s理論模式;肋條通道雙極板;流場速度分佈量測;flow velocity distribution measurements;rib-channel flow distributors;Kee＇s model;Internal manifolds of fuel cell stacks
日期:	2010-08-25
上传时间:	2010-12-08 13:40:54 (UTC+8)
出版者:	國立中央大學
摘要:	本研究實驗量測可適用於平板式固態氧化物燃料電池(SOFC)堆之內歧管(internal manifold)內的流場分佈，主要目的乃實驗評估Kee et al. (2002)所提出之Z型肋條流道(rib-channels)SOFC電池堆流場分佈數值理論模型的可靠度，其中Z型指流體流經進口區(feed header)與出口區(exhaust header)之流向配置為同向。利用自行建立之水力模型平台，搭配二維雷射誘導螢光法來獲取電池堆內各層內以許多肋條分隔之矩形流道的流場影像，再利用二值化影像處理與MATLAB軟體進行計算與分析，進而獲得電池堆內各層內不同流道之流場分佈並統計估算其流場不均勻度。有關Kee＇s理論模型，其假設流場為層流定常狀態之不可壓縮流，考慮不同高度之水靜壓，從連續方程式與動量方程式推導，再將其無因次化，提出可適用於Z型流道分佈板之流場不均勻度預測模式，主要由一無因次化參數NcWlGl=constant所控制，其中Nc為流道數目、Wl為無因次化單位壓力差下所造成的質量流率、Gl為無因次化黏滯阻力項，而有關不均勻度則以流場板內流道之最大與最小質量流率差值除以最大質量流率來定義之。Kee＇s模式共有8組不同NcWlGl值，因實際模型製作的限制，我們僅能選定其中3組作為驗證，分別為NcWlGl=0.81、5.23與8.11，其中我們先以NcWlGl=0.81之單層流道分佈板，含10個、25個和50個不同流道，作為測試流道數目變化的基準，實驗結果顯示，三個具不同流道數目之流場分佈相當近似，顯示Kee＇s理論模式可大致適用於不同流道數目之流場分佈。有關電池堆研究，我們以 5.23和8.11為研究對象，並使用10個流道數目之六層電池堆模型，實驗結果與Kee＇s模式具有相同之趨勢。在多層電池堆流場狀態下，越下層之流場板因受重力效應影響，其質量流率較大，不過各層流場分佈之趨勢仍與Kee’s理論模式所預測之分佈相當吻合。先前之研究多以數值模擬方法探討理論模型，本研究首度以實驗方式驗證Kee＇s燃料電池堆流場分佈模式之適用性及誤差範圍，應對多層電池雙極板流場分佈之設計有所貢獻。 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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