A high-efficiency scheme for waste heat harvesting of solid oxide fuel cell integrated homogeneous charge compression ignition engine

Abstract Facing the energy shortage and environmental pollution problems in the world, a high-efficiency fuel cell scheme combined with waste heat recovery is regarded as an optimal selection of auxiliary power generation equipment for ships. In this study, a novel system, comprising solid-oxide-fuel-cell-preheating subsystem, homogeneous charge compression ignition engine and organic Rankine cycle, is designed and analysed. First, the mathematical model is established and verified to ensure the reliability of simulation results. Then, the effect of relevant parameters on homogeneous charge compression ignition engine performance is observed, and the optimal zeotropic working fluid of organic Rankine cycle is determined according to the exhaust temperature. Finally, the thermodynamic and economic analysis are carried out. The results indicate that the performance of the new system is better than that of the traditional combined system using gas turbine. Thermal efficiency and exergy efficiency of the system are more than 63.6% and 61.3%, which is about 18.76% and 17.95% higher than that of simple cell. In addition, the payback time is about 2.98 years, which is about half of the traditional combined system and can fully meet the economic requirements. This novel system can be a new selection of marine auxiliary power generation equipment.