Akademik Veri Yönetim Sistemi
Tezin Türü: Yüksek Lisans
Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Türkiye
Tezin Onay Tarihi: 2013
Tezin Dili: İngilizce
Öğrenci: Yasemin Saygılı
Eş Danışman: İNCİ EROĞLU, SERKAN KINCAL
Açık Arşiv Koleksiyonu: AVESİS Açık Erişim Koleksiyonu
Özet:Polymer electrolyte membrane (PEM) fuel cells attract an extensive interest due to their advantageous properties. To compete with the conventional power generators fuel cell systems should ensure safe and efficient operations at any time. To achieve satisfactory operations, all the process requirements should be determined and implemented within the operational constraints. Thermal management, reactant supply, water management and power management are some of the main issues for which proper and sufficient control strategies should be developed and implemented by the control system. In this study a portable 3kW PEM fuel cell system is modeled to understand the system dynamics. The system model includes the fuel cell stack, humidifier, compressor, inlet and outlet manifolds, and cooling system. Model development is carried out by the mass and energy balances, thermodynamics and kinetics. To define unknown system parameters some experiments are performed on stack and the cooling system and a semi-empirical model is constructed. For the compressor a feedback (PI) controller is combined with a static feed-forward controller. It is observed that the compressor adapts to dynamic changes within small durations. A membrane type, shell and tube structured humidifier is modeled and compared with literature and a reasonable agreement is observed. Two different humidifiers are simulated to see the effect number of tubes involved in humidifier. It is observed that increasing the number of tubes results in better humidification as expected. Three different control strategies are analyzed for the cooling system involving a pump, radiator and fan. The performances of different controllers for thermal management are evaluated in terms of stack temperature, integral time weighted absolute error (ITAE) and the parasitic energy requirements. Minimizing fan usage with an on/off controller while keeping the pump voltage as a variable gives better results. MATLAB Simulink is used for development and implementation of models and controllers.