Design and Performance Study of a Solid Oxide Fuel Cell and Gas Turbine Hybrid System Applied in Combined Cooling, Heating, and Power System

Abstract

Because of their high efficiency and very low emissions, fuel cells have been one of the choice areas of research in current energy development. The solid oxide fuel cell (SOFC) is a type of high-temperature fuel cell. It has the characteristic of a very high operating temperature of 1,027°C (1,300 K). The SOFC has the main advantage of very high performance efficiency (more than 50%) but also has very high exhaust temperatures. Current studies point out that the combination of the SOFC and gas turbine (GT) can produce efficiency of more than 60%. The exhaust temperature of this hybrid power system can be as high as 227–327°C (500–600 K). With this waste heat utilized, it is possible to further improve the overall efficiency of the system. A simulation program of the SOFC/GT system and the introduction of the concept of combined cooling, heating, and power (CCHP) system have been used in this study. The waste heat of the 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, the authors have a combined CCHP system developed using three major modules—the SOFC, GT, and ARS modules. The SOFC module was verified by the authors’ test data. The GT and SOFC/GT modules were compared with 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 the authors’ definition could be more than 100%, especially for the double-effect ARS. This analysis system was demonstrated to be a useful tool for future CCHP designs with SOFC/GT systems.