Development and optimization of a novel solid oxide fuel cell-engine powering system for cleaner locomotives

Due to the advantages of high efficiency and fuel flexibility, solid oxide fuel cells have become a prominent option to power the future of heavy-duty transportation. Providing and selecting several solid-oxide fuel cell-based powering systems as options for the transportation industry have become an important task. For this reason, the purpose of this paper is to propose a novel powering integrated system for cleaner rail transportation. A partially-premixed compression ignition engine is integrated for the first time with a solid oxide fuel cell instead of a simple compression ignition engine to evaluate the integrated system performance for locomotives. A detailed thermodynamic model based on energy and exergy analyses is developed and used to evaluate the new powering system. The power split between the fuel cell and the engine effects on the overall exergy efficiency and total space requirements are explored for the first time in an integrated solid oxide fuel cell-based system through a newly developed optimization procedure using a sequence of multi-objective optimization methods. At the reference case, the overall energy and exergy efficiencies are 80.1% and 77.6%, respectively, which are around 15% more efficient than a simple solid-oxide fuel cell-gas turbine powering system, because of the new fuel cellengine integration. The overall exergy efficiency is 78.98% and the total space requirement is 30.73 m(3) at the optimum operating point. Moreover, the further originality of this paper is to develop and optimize the performance and sizing of the present integrated system for a limited-space application, namely locomotives.