| 摘要: | 本論文研究使用已建立之高溫高壓雙腔體固態氧化物燃料電池(SOFC)實驗測試平台，搭配自製鈕扣型和平板型單電池測試載具，使用陽極支撐全電池片(Anode-Supported Cell, ASC)量測其電池性能曲線與電化學阻抗頻譜圖，探討改變溫度、燃料濃度、壓力、流率對電池功率密度之影響。本論文包含三個部分:(1)使用鈕扣型全電池，測試氨於四個不同操作溫度:700、750、800、850oC與三種不同濃度:高濃度(75/25 sccm H2/N2和50 sccm NH3)、中濃度(60/40 sccm H2/N2和40/20 sccm NH3/N2)和低濃度(45/55 sccm H2/N2和30/40 sccm NH3/N2)條件下之溫度和濃度效應；(2)使用平板型全電池，在兩種不同總流率(900/1800 sccm)和溫度850oC，每個流率在三個操作壓力(1、3、5 atm)條件下，其壓力和流率效應對電池功率密度之影響；(3)建置大面積平板型100 mm x 100 mm SOFC載具，並量測操作溫度在750oC之電池性能與阻抗頻譜。第一部分結果顯示，提高操作溫度、燃料濃度均能提高電池性能，這是因為增加溫度會使歐姆阻抗降低，且能使電解質層的離子傳導率與電極之電子傳導率上升。增加濃度能使阻抗頻譜之低頻濃度極化阻抗減少，而降低極化阻抗可使電池性能提升。第二部分結果顯示，增加壓力能有效提升電池性能，而當電池獲得充足燃料時，再增加燃料流率並不會使電池性能增加。加壓會造成流道中燃氣流速下降，因質量守恆，密度增加，流速減少，氣體經特製加熱蛇型彎管可獲得均勻加熱，且加壓可增加氣體擴散效率，故加壓能有效提升電池性能。第三部分為新建置的大面積SOFC平板型100 mm x 100 mm載具，它與50 mm x 50 mm平板型載具之構置相同，均由陰、陽極載具、集電層、以及陶瓷材料所加工的流道板所組構而成，我們測試其在操作溫度750oC之電池性能，結果顯示使用氨為燃料其電池性能幾乎與氫燃料相近。本研究成果對於氨SOFC之基礎知識有重要之助益。;This thesis applies an established high-pressure and high-temperature solid oxide fuel cell (SOFC) testing platform to measure the cell performance and electrochemical impedance spectroscopy (EIS) of button- and planar-type anode-supported cell (ASC). We investigate effects of the temperature (T), fuel concentration, pressure (p), and the flow rate on the cell power density. There are three parts in this thesis: (1) The effects of temperature and concentration on the cell performance of the button ASC using both hydrogen and ammonia fuels under various temperature conditions (700,750,800,850oC) and different fuel concentrations varying from high concentration (75/25 sccm H2/N2 ; 50 sccm NH3), and middle concentration (60/40 sccm H2/N2 ; 40/20 sccmNH3/N2) to low concentration (45/55 sccm H2/N2 ; 30/40 sccm NH3/N2) ; (2) the measurements of the planar ASC performance using two different total flow rates (900/1800 sccm) at a temperature of 850oC, each flow rate including three different operating pressures (1,3,5 atm); (3) a preliminary test for a large planar (100 mm x 100 mm) SOFC at 1 atm and 750oC to measure its cell performance and EIS data. Results show that the cell performance increases with increasing T as well as increasing the fuel concentration. This is because the ohmic polarization decreases with increasing T that increases the ionic conductivity of the electrolyte layer and the electron conductivity of the electrode. Increasing the fuel concentration can reduce the impedance of arc in the impedance spectra, thus improving the cell performance. The cell performance increases with increasing p. When the cell is supplied by sufficient fuel, a further increase of the fuel flow cannot increase the cell performance. Pressurization decreases the gas flow velocity in the flow channel, because of the conservation of mass, where the density increases with pressure resulting in a decrease of the flow velocity. Fuel can be uniformly heated when using a specially-designed serpentine heating pipe system. Besides, pressurization increases the efficiency of gas diffusion and thus it can increase the cell performance. A new SOFC large-area planar 100 mm x 100 mm test rig is established, having the same design of 50 mm x 50mm planar SOFC, which is consisted of cathode and anode carriers, two collector layers, and ceramic material flow distributors. The measured of cell performance of the large-area planar SOFC at 750oC indicates the successful operation of such cell. Furthermore, the cell performance using ammonia as a fuel is almost the same as that using hydrogen as a fuel. Finally, these results should be useful to our basic understanding of ammonia SOFC. |
