Solid oxide fuel cell–internal combustion engine hybrid system utilizing an internal combustion engine for anode off-gas recirculation, external reforming, and additional power generation

Abstract

A solid oxide fuel cell (SOFC)-internal combustion engine (ICE) hybrid system is proposed and analyzed. Although the existing SOFC-ICE hybrid system improves the efficiency of the SOFC stand-alone system by deriving additional power from the anode off-gas in the ICE, the proposed hybrid system further increases the system efficiency by utilizing the ICE for anode off-gas recirculation, external reforming, and additional power generation. Accordingly, we developed models for the SOFC and ICE and performed simulations to understand the operational characteristics of the hybrid system. Through simulation, the influence of each control parameter was analyzed, and the system operable ranges were determined according to the rate of system heat loss. When the heat loss considered is the least, a gross system efficiency of 66.9% is achieved at the optimum point. Thus, this study developed a high-efficiency SOFC-ICE hybrid system by combining methods that utilize the ICE as a recirculation blower, reformer, and power generator.