加壓型固態氧化物燃料電池量測與分析:壓力、溫度與質量流率效應

Measurements and Analyses of Pressurized Solid Oxides Fuel Cells: Effects of Pressure, Temperature, and Mass Flow Rates

鄭浩昇(Hao -Sheng)

指導教授 ： 施聖洋

國立中央大學/工學院/機械工程學系/碩士(2012年)

摘要

本論文利用本實驗室已建立之高壓雙腔室固態氧化物燃料電池(solid oxide fuel cell, SOFC)性能量測平台，針對含流道板之單電池堆進行電池性能與阻抗頻譜之定量量測與分析，以了解壓力、溫度、流場均勻度與陰陽極流率等效應對加壓型SOFC之影響。實驗平台包含一大型高壓腔體，內置一高溫爐，其中放置一由陽極支撐電池片、crofer-22-APU框架、集電層與一對肋條式陶瓷流道板堆疊而成的單電池堆。實驗結果含三大重點，分別為在不同加壓條件下(1 ~ 5 大氣壓)(1)流場均勻度效應，(2) 溫度效應，和(3)陰、陽極流率變化效應對單電池堆之電池性的影響。(1)利用本研究團隊先前所設計得有導流裝置之流道板(具優化流場均勻度)與未加導流裝置之流道板(具較差之流場均勻度)作比較，發現流場均勻度之改善可有效提升單電池堆之性能，並且此性能提升會隨壓力增加而更加顯著，相關之阻抗頻譜將用以解釋此一結果。(2)在壓力和流率等操作條件固定時，溫度從650℃提升至800℃下，雖然單電池堆性能會隨溫度上升而提高，但開迴路電壓(OCV)反而會些微下降。這是因為溫度提升對阻抗下降有所助益，使電池性能有所提升，此趨勢在壓力1 ~ 5大氣壓中皆相同。在任一固定溫度條件下(T = 650℃、700℃、750℃和800℃，加壓皆會使功率密度與OCV提升，由阻抗頻譜量測資料，可知這是因為活化極化與濃度極化皆會隨著壓力提升而下降。(3)在操作溫度T = 850℃和陽極流率固定(0.5 slpm H2 + 0.5 slpm N2)時，單電池堆性能將會隨陰極空氣流率增加(空氣流率0.5 slpm、0.75 slpm與1 slpm)而提升，且壓力越高，其提升越明顯。但是，陰極流率固定( 0.5 slpm air)時，單電池堆性能並未因陽極流率增加而顯著提升。顯示陰極流率的變化較陽極流率的變化對單電池堆性能之影響較為敏感。本論文所獲得知結果應該有助於未來發展高效率加壓型SOFC結合GT之複合系統。

關鍵字

壓力效應 ； 高壓雙腔室固態氧化物燃料電池 ； 阻抗頻譜 ； 功率密度

並列摘要

This thesis uses the recently-established high-pressure double-chamber solid oxide fuel cell (SOFC) testing platform to quantitatively measure cell performance and electrochemical impedance spectra (EIS) of single unit cells with flow distributors, so that the effects of pressure (p), temperature (T), flow uniformity in interconnects, and the flow rates of anode and cathode in pressurized SOFCs can be studied. The testing platform from outside in includes an outer high-pressure chamber, a high-temperature controllable, and a single cell stack (single unit cell + two flow distributors). The single cell stack is consisted of an anode-supported unit cell, the crofer-22-APU supporting frames, and the two current collectors which are sandwiched by a pair of rib-channel flow distributors. The present experimental studies have three parts concerning various effects to the cell performance under elevated pressure conditions (p = 1 ~ 5 atm): (1) The effect of flow uniformity in flow distributors, (2) the effect of operating temperature (T), and(3) the effect of flow rates in both anode and cathode electrodes, as shown below respectively. (1) By comparing two different designs of rib-channel flow distributors using or not using small guide vanes in the same single-cell stack, the one with guide vanes having much higher flow uniformity than that without guide vanes has a better cell performance. Such enhancing performance due to the increasing degree of flow uniformity is found to be even more profound at higher pressure conditions, as can be electrochemical understood and explained by electrochemical impedance spectra (EIS) measurements. (2) While keeping p and the flow rates constant, the single-cell stack performance increases with T at least from 650℃ to 800℃ for all value of p = 1~5 atm studied. However, the open-circuit-voltage (OCV) is slightly reduced by increased T. At any fixed value of T, pressurization can increase OCV and the cell power density. From EIS measurements, it is found that both activation and concentration polarizations decrease with increasing p explaining why the cell performance is increasing with p. (3) At T = 850℃ and fixed anodic flow rate (0.5 slpm H2 + 0.5 slpm N2), the performance of the single-cell stack can be increased by increasing the air flow rates of cathode at least over the range from 0.5 slpm to 1 slpm. This increase is even more profound at higher p. On the other hand, the cell performance of the single-cell stack is rather insensitive to the increase of the anodic flow rates while keeping the cathodic flow rates constant (0.5 slpm air).
These results should be useful to the development of pressurized SOFC integrating with gas turbines for future hybrid power generating system.

並列關鍵字

high-pressure double-chamber solid oxide fuel ce

參考文獻

[1] Gregor, H., Fuel cell technology hand book, CRC Press, Germany, 2003.

[2] James, L., Andrew, D., Fuel Cell Systems Explained 2nd, U.K., 2003.

[4] 張軒維，加壓型固態氧化物燃料電池型能與阻抗之定量量測與分析，碩士論文，國立中央大學，2011。

[5] Park, S., Kim, T.S., Comparison between pressurized design and ambient pressure design of hybrid solid oxide fuel cell-gas turbine system,J. Power Sources, Vol. 163,pp.490-499,2006

[6] Zhou, L., Cheng, M., Yi, B., Dong, Y., Cong, Y., Yang, W., Performance of an anode-supported tubular solid oxide fuel cell (SOFC) under pressurized conditions, Electrochi. Acta, Vol. 53, pp. 5195-5198, 2008.