本研究針對中溫型固態氧化物燃料電池(Solid Oxide Fuel Cell, SOFC)系統進行模擬，首先利用Matlab/Simulink分別模擬傳統氧離子傳導與氫離子(質子)傳導型SOFC，400 °C到700 °C之間的單電池的性能曲線，經由比較可知在中溫範圍，質子傳導型具有較佳的性能，這是因為BCSO電解質材料比YSZ電解質材料在中溫時有更佳的導電度。Thermolib進行系統模擬時，使用中溫質子傳導SOFC。基本系統由燃料電池堆、混合器、重組器、熱交換器與後燃器所組成。模擬條件為燃料電池之操作溫度在450 °C到650 °C之間，操作於最大功率或0.7V。在分析上， 改變不同燃料量探討系統的電堆效率、系統淨電功輸出效率與系統熱電效率，由結果得知，650燃料量擁有最高的熱電效率，450燃料量擁有最高的電效率，在相同級數的熱回收下，0.7V的熱電效率會優於操作在最大功率系統；接著再改變不同的系統設計，在系統最後加入熱回收系統與渦輪機，可以增加系統的電功輸出，但回收的熱能會些微的下降；在渦輪機的配置上，將渦輪機置於後燃機後，渦輪機可以利用到高溫廢氣，加上降低系統溫度，可以減少空氣壓縮機的功耗，是本文中最佳的渦輪機配置方法。This study investigates the performance of intermediate temperature (IT) solid oxide fuel cell (SOFC) systems. By using Matlab/Simulink, the traditional oxygen ion conducting and the hydrogen ion (proton) conducting SOFC I-V curves are built for the temperature range from 400 to 700 °C by considering various polarization losses. In this temperature range, the performance of proton conducting SOFC is better due to the higher conductivity of proton conducting electrolyte in IT range. The system consists of a fuel mixing chamber, a reformer, a SOFC stack, heat exchangers, and an after-burner. The SOFC stack operates between 450 and 650 °C at the maximum power or 0.7V conditions. The basic heat recovery strategy is using exhaust gas to warm up water to 60 °C. The efficiencies of the net electric power output for cell stack and for the overall system, and the combined heat and power (CHP) are investigated for different fuel flow rates. Results show that the fuel flow rate which is required for the maximum power output in 650 °C has the highest heat recovery, and the 450 °C one has the highest electrical efficiency. The CHP efficiency of the system operating at 0.7V is better than that at maximum power. Effects of system design are also studied by considering adding extra heat recovery components and turbine to the system. The modified designs can increase the electrical power output, but decrease the heat recovery slightly. Placing the turbine after the afterburner can provide the maximum power output by receiving the highest temperature of exhaust gas and reduce the power consumption of the air compressor by decreasing the system temperature. This configuration has the highest efficiency for the cases considered in this work.
