Ch <sub> 4 </ Sub>-h <sub> 2 </ Sub> O, H <sub> 2 </ Sub>-co-fueled Solid Oxide Fuel Cell Power Generation Performance

Solid oxide fuel cell (SOFC) is an all solid-state energy conversion device operated at high temperatures with the advantage of high efficiency and fuel adaptability. Aiming at fuels such as natural gas, syngas and coal gas which are widely used in industry, electrical performance of SOFC fueled by CH4-H2O and H2-CO is studied. And this provides the foundation for the next research work on electrode reactions and kinetics.This paper consists of three parts mainly:1) Electrolyte-supported single SOFCs are prepared, which are constructed from YSZ electrolyte with Ni-YSZ anode and LSM cathode. The morphologies of cells are examined by scanning electron microscopy. The porosity and particle dispersing in cathode are apparently superior to that in anode, so anode becomes an important factor that restricts cell performance. The results from energy spectrum analysis show that carbon deposition is found after cells are used.2) A experimental set for measuring electrical performance of single cells is built. The influences of operating conditions such as fuel composition, fuel concentration, and temperature on electrical performance of single cells are studied experimentally. And stability of cell performance is tested. For the CH4-H2O fuel system, while the rate of steam to methane is equal to 1, cell performance is most perfect. While the rate of steam to methane is equal to 2, cell performance for long time operation is very stable, which shows that steam can avoid carbon deposition effectively at this situation. For the H2-CO fuel system, cell performance fueled by coal gas is comparable with that fueled by syngas. At the range from 700℃ to 1100℃ the maximum power density is linear to the operating temperature.3) A mathematical model is presented to analyze polarization characteristic of single cells, in which different operating conditions and cell microstructure structures are considered. The codes are programmed using MATLAB. Then the influences of cell component thickness and temperature on cell performance are analyzed using calculated result from this model. The performance of anode-supported cells is apparently superior to cells which are supported by electrolyte. The cell performance can be improved by decreasing the electrolyte thickness and increasing the operating temperature. Compared with experimental data, the average error of calculated results is 13.1%, which is caused by neglect of interface contact impedance and carbon deposition in this model.