Performance Study On Solid Oxide Fuel Cell Proper And Combined Power Generation

With the aggravation of the global environmental pollution, it is more important to utilize the energy resource favorably and exploit the clean energy resource. Solid Oxide Fuel Cell (SOFC) is devices capable of converting chemical energy into heat and dc electric energy by means of the oxidation of a fuel, usually hydrogen. Fuel cells have the following advantages over conventional generating systems: low environmental pollution; highly efficient power generation; diversity of fuels; reusability of exhaust heat; modularity; faster installation. As the most prospective technique, fuel cell is developed rapidly in the late 30 years.The fuel cell generation research significance and the background of this thesis are summarized in the first chapter. The necessity of development fuel cell generation technology in China's power system is verified, and technical line for developing fuel cell generation is put forward. A description of what a fuel cell is, how it works, the different types of fuel cells, and advantages and disadvantages of fuel cells are also given. The design structure and the development of SOFC in our country and overseas are also introduced.Secondly, a model was developed to simulate the operation of a tubular SOFC at the steady operation states. The model includes all the three polarizations: ohmic, activation and concentration polarization. The effects on SOFC voltage and power of operating temperature, pressure and fuel utilization of the steady operation are analyzed in detail.Finally, SOFC power systems fed methane were examined with thermodynamic and exergy modeling of SOFC. In order to obtain high efficiency and optimize the total system, the exergy concept has been used to analyze these systems, and pinpoint the thermodynamic losses in each unit and to access the work potentials of the streams of matter. The results show that an internal-reforming hybrid SOFC-gas turbine system could achieve an electrical efficiency of more than 60% and a total efficiency of combined heat and power about80%.