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الثلاثاء، 5 أغسطس، 2014

Thermo-Energetic Analysis of solid Oxide Fuel Cell Hybrid Systems for Marine Application


Author        : Nader Ragab Youssef Ammar
Degree        : Ph.D. Marine
Title: Thermo-Energetic Analysis of solid Oxide Fuel Cell Hybrid Systems for Marine Application

Abstract
Strong restrictions on emissions from marine power plants particularly sulphur oxides and nitrogen oxides will probably be adopted in the near future. At the same time, the need to reduce fuel consumption, and therefore the cost of fuel used, is stimulating the exploration of alternatives for energy production with better waste energy utilization. Furthermore, LNG is one of the suitable fuel solutions. In the power generation, fuel cell hybrid systems operated with natural gas fuel are an attractive option. In addition, integrating the waste heat recovery systems (WHR) with natural gas fuel for the current marine diesel engines and marine gas turbines can be a good solution.
Fuel cells are electrochemical devices that directly convert chemical energy in fuels into electrical energy, allowing power generation with high efficiency and low environmental impact. Because the intermediate steps of producing heat and mechanical work typical of most conventional power generation methods are avoided, fuel cells are not restricted by thermodynamic limitations of heat engines such as the Carnot efficiency. In addition, because combustion is avoided, fuel cells produce power with minimal pollutant. The most promising options for marine applications are Solid Oxide Fuel Cell (SOFC) and Proton Exchange Membrane Fuel Cell (PEMFC). The reason for preferring SOFC to be used in power generation is due to its higher operating temperature which can reach IOOO°C. Furthermore, the higher temperature fuel cells can favor the conversion of CO and CH4 to hydrogen, and then use the equivalent hydrogen as the actual fuel.
Therefore, in this thesis a simple model for SOFC has been developed. The model includes chemical and thermodynamic relations governing the fuel cell operation and also the effect of operating conditions on cell performance. Understanding the impact of various parameters such as temperature, pressure, and gas constituents on performance allows fuel cell developers to optimize their design of the modular units and allows process engineers to maximize the performance of system applications. Tn addition, the thesis includes a detailed thermodynamic analysis for the SOFC hybrid systems. Mass and energy balances are performed not only for the whole plant but also for each component in order to evaluate the thermal efficiency of the combined cycle. The effect of using natural gas as a fuel on the fuel cell voltage and performance is also investigated.

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