Chien-Hsiung Lee

Experimental Investigation of 1 kW Solid Oxide Fuel Cell System with Hydrogen Fed Fuel and an Exhaust gas Burner

Compared to other fuel cell types, solid oxide fuel cell (SOFC) have a number of attractive features: fuel flexibility, components that are all solid state, no water management issues, and high quality surplus heat for combined heat and power (CHP). The aim of this paper is to investigate the optimal operation condition of porous media burner (so called after-burner) in a SOFC power system. The functions of after-burner are to increase the thermal efficiency and to decrease the harmful emissions of anode off gas for the SOFC operation. In order to find the optimal operation condition of after-burner, the experimental investigation of after-burner control logic is needed. The key manipulation parameters and the optimal after-burner operation conditions are presented in this paper. The experimental results show that the optimal after-burner operation is obtained when using an anode off-gas temperature of 650°C, a cathode off-gas temperature of 330°C, a flame barrier temperature of 700°C, an excess air ratio of 2 and a fuel utilization of U(subscript f) =0.6. Finally no extra fuel and additional cooling air are fulfilled under the long term operation of SOFC system and the simulations from burner ignition to SOFC long term operation period are also conducted.

Design and Performance Analysis of a Solid Oxide Fuel Cell/Gas Turbine (SOFC/GT) Hybrid System Used in Combined Cooling Heating and Power System

With high efficiency and very low emissions, fuel cells have been one of the choices of research in current energy development. The Solid Oxide Fuel Cell (SOFC) is a high temperature type fuel cell. It has the characteristic of very high operating temperature 1,027°C (1,300K). The SOFC has the main advantage of very high performance efficiency (over 50%), but also has very high exhaust temperature. Current studies point out that the combination of SOFC and Gas Turbine (GT) can produce efficiency more than 60%. The exhaust temperature of this hybrid power system can be as high as 227–327°C (500–600K). With this waste heat utilized, we can further improve the overall efficiency of the system. A simulation program of SOFC/GT system and the introduction of the concept of Combined Cooling, Heating, and Power System (CCHP) have been used in this study. The waste heat of SOFC/GT hybrid power generation system was used as the heat source to drive an Absorption Refrigeration System (ARS) for cooling. This waste heat enables the SOFC/GT to generate electricity in the system while providing additional cooling and heating capacity. Therefore, we have a combined CCHP system developed using three major modules which are SOFC, GT, and ARS modules. The SOFC module was verified by our test data. The GT and SOFC/GT modules were compared to a commercial code and literature data. Both the single- and double-effect ARS modules were verified with available literature results. Finally, the CCHP analysis simulation system, which combines SOFC, GT, and ARS, has been completed. With this CCHP configuration system, the fuel usability of the system by our definition could be above 100%, especially for the double effect ARS. This analysis system has demonstrated to be a useful tool for future CCHP designs with SOFC/GT systems.Copyright

Thermal Stress Analysis for a SOFC Testing Cell

Solid Oxide Fuel Cell (SOFC) is operated at elevated temperatures of 650-1000℃. Under such high temperatures, several issues need to be overcome. Among then, the thermal stresses because of the mismatch of thermal expansion coefficients of components is one of the most important issue. The typical materials used for anode, electrolyte, and cathode in SOFC are all ceramic materials which are brittle and prone to fail due to excessive stresses. In this paper, a prototype SOFC single test cell, which consists of PEN, gas distributors and Air/Fuel pipings, is constructed. To analyze the thermal stress distribution of the test cell, the commercial code MARC is employed to carry out stress/thermal analysis. In the calculations, temperature field is provided by CFD code, STAR-CD and electrochemical module ES-SOFC. The analysis results will be offered to improve the cell/stack design.