Abstract
Cycle simulations were made on SOFC-Stirling engine combined systems fueled with methane and hydrogen to investigate the feasibility of the combined systems. The model system consisted of a SOFC with internal reforming, a combustor burning the exhausted fuel from the SOFC, a conventional Stirling engine and an air-preheater recovering the exhausted heat from the engine. In the system, SOFC served simply as the topper of the engine. The cycle calculation was mainly focused on the influences of temperature efficiency of the preheater and the number of transfer unit of the Stirling engine heat exchanger on the system efficiency and the operation conditions. The methane system revealed that the efficiency attains up to 52% at reasonable temperature efficiency of 0.8, while the operation is restricted in a narrow range of the number of transfer unit by the maximum preheater temperature and the minimum temperature at SOFC inlet. The hydrogen system requiring no reforming showed a higher efficiency and a wider operation range than the methane system.
