本論文量測加濕效應與壓力效應對甲烷固態氧化物燃料電池(Solid Oxide Fuel Cell, SOFC)電化學性能、碳沉積與電池穩定性之影響。採用實驗室已建立之加壓型SOFC測試平台，使用鈕扣型陽極支撐電池(Ni-YSZ/ YSZ/ LSC-GDC)，於操作壓力p = 1 atm 與3 atm和操作溫度750°C，進行四種不同濕度比例之甲烷作為陽極燃料，以steam to carbon ratio (S/C)定義，分別為(1) S/C = 0 (50 sccm CH4 + 150 sccm N2)、(2) S/C = 0.25 (50 sccm CH4 + 12.5 sccm H2O + 137.5 sccm N2) 、 (3) S/C = 0.5 (50 sccm CH4 + 25 sccm H2O + 125 sccm N2) 以及(4) S/C = 1 (50 sccm CH4 + 50 sccm H2O + 100 sccm N2)，陽極總體積流率為200 sccm；陰極則是通入200 sccm的空氣。實驗結果顯示：在p = 1 atm下，甲烷加濕效應可使SOFC功率密度提升14% ~ 26%，最大提升值發生在S/C = 0.25，這是因為甲烷蒸氣重組反應將CH4轉換成H2，得以有效地降低活化極化與濃度極化。再者，壓力效應與加濕效應結合明顯降低SOFC極化阻抗，例如加濕甲烷在p = 3 atm和S/C = 0.5條件下，其電池性能比起常壓和S/C = 0.5條件下之性能高出62%。在p = 3 atm和S/C = 0條件下，於 SEM與XRD影像觀測到有大量的碳沉積聚集於燃料進口處，這是因壓力效應加劇了甲烷與陽極鎳觸媒直接裂解的速率，提高S/C可藉由甲烷蒸氣重組，與水煤氣轉換反應抑制於燃料進口處之碳沉積，達到延長電池壽命的目的。綜合以上結果，顯示加壓型甲烷SOFC配合適度加濕，未來可與直接燃燒甲烷(天然氣主要成份)之微氣渦輪機結合，發展分散式高效率複合式發電系統。;This study meassures the effect of humidification on carbon deposition for a pressurized methane-fueled solid oxide fuel cell (SOFC) using anode-supported button full cell (ASC: NiO-YSZ/ YSZ/ LSC-GDC). Experiments are conducted in high-pressure SOFC testing platform. The experimental conditions are two operating pressures p = 1 atm and p = 3 atm at T = 750 °C. The anode fuel is supplied by methane with four different steam to carbon ratio (S/C): (1) S/C = 0 (50 CH4 + 150 N2), (2) S/C = 0.25 (50 CH4 + 12.5 H2O + 137.5 N2), (3) S/C =0.5 (50 CH4 + 25 H2O + 125 N2), (4) S/C =1 (50 CH4 + 50 H2O + 100 N2) at a total flow rate of 200 ml min-1, and the cathode is supplied by air at a total flow rate of 200 ml min-1 for all four cases . Results show that steam-methane reforming can improve power density and reduce both activation and concentration polarization noticeably. Moreover, the maximum power density is formed to be at S/C = 0.5 with p = 3 atm, which significantly increase of 62% as compared with that at p = 1 atm and S/C = 0.5. The scanning electron microscope (SEM) and X-ray diffraction (XRD) images show great amount of carbon deposition at S/C = 0 with p = 3 atm. The carbon deposition can be suppressed by increasing S/C under steam-methane reforming and water-gas shift reaction, which is turn extends the cell durability. This suggests that the pressurized methane-fueled SOFC is feasible for the future development of the hybrid power system integrating with micro gas turbines.
