| Summary: | 碩士 === 國立中央大學 === 機械工程學系 === 104 === Abstract
Conducting Proton-Solid Oxide Fuel Cell (pSOFC), by attaching Micro Gas Turbine (MGT) is oneof the outstanding hybrid system nowadays. The intermediate temperature of pSOFC (around 700 – 800 [0C])is used to raise the performance of micro gas turbine in apower plantsystem. pSOFC has a lower temperature characteristic than old type of SOFC, which can afford more rapid start up/down and improve durability. A new model is proposed in the research based on themodels developed by earlier researchers.The proposed hybrid system is simulated using Matlab-Simulink. Simulations were performed to study the behavior of the pSOFC-MGT hybrid system by changing respective parameters such as pressure, steam to carbon ratio, and fuel utilization.In our research, we proposed, three different configurations by changing the bypass position in my proposed system i.e., with placing the bypass(i) after the combustor, (ii) after turbine, and (iii) after the combustor and turbine.
The results show that the higher operating pressure will reduce system efficiency for configuration 1 and 2, and increase the efficiency for configuration 3. The effect of raising Steam to Carbon Ratio will reduce the efficiency of configuration 1 for anoperating pressure of 1 – 2 [bar], but it increasesthe efficiency of configuration 2 and configuration 3. The higherfuel utilization will increase the efficiency for all configurations. For bypass ratio variation, increase in bypass ratio will increase the efficiency of all configurations. Considering all the results ofconfiguration 3 provide the best performance compared to configuration 1 and 2 in all three models. The efficiencies of configuration 1, configuration 2, and configuration 3 are 49%, 63%, and68% respectively. The study obtained that using the overall heat exchanger over 5 W/K will not give an effect to configuration 3 performance so much. The cost analysis can be taken into consideration bychoosing an appropriate device to build a configuration 3 model. The exergy analysis has a same tendency with energy analysis, but it will different in value. Due to the exergy destruction during the process, the value of energy is higher than exergy. To know an amount of exergy destruction, it carried out thecalculations based on the amount of entropy generation and found the devices that have lost exergy from the largest to the smallest in a sequence is combustor 60.2[kW], pSOFC 22.8 [kW] Compressor 21.7 [kW], Pump 5.5 [kW], Fuel Heater 0.9 [kW], reformer 0.7 [kW], water heater 0.4 [kW], air heater 0.23 [kW], and MGT 0.21 [kW].
Keywords: Proton-Conducting Solid Oxide Fuel Cell (pSOFC), Micro Gas Turbine (MGT), Matlab-Simulink, Hybrid configuration mode
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