Analysis and optimization of fuel cell based integrated powering systems for clean rail applications

Abstract

In this thesis, proposals of novel integrated fuel cell powering systems for cleaner railway applications are presented and analyzed thermodynamically. Both energy and exergy analyses are conducted on these systems for such an application to evaluate and compare them thermodynamically, in terms of their power outputs capabilities and energetic and exergetic efficiencies. Next, parametric studies on each of the proposed integrated fuel cell systems are provided to have a deeper understanding of the operation of these systems under various conditions. This understanding can help us in the optimization of exergetic efficiency and packaging feasibility of the systems in a locomotive. A newly introduced method of multi-objective optimization is implemented to optimize the integrated systems in terms of exergetic efficiencies, power split for space reductions, and hydrogen production rate. Lastly, economic and environmental justifications are given through a case study of a duty cycle of a passenger train. Fuel costs and CO2 emissions of these proposed integrated systems are compared to the current technology of diesel-electric engines used in railways of Canada. The thermodynamic analysis shows that these systems can reach high energetic and exergetic efficiencies of 80.06% and 77.55%, respectively for methane-based solid oxide fuel cell systems, while ammonia-based systems have the values of energetic and exergetic efficiencies of 61.20%, and 66.30%, respectively. Fuel costs of passenger train operation, using these proposed systems, are significantly reduced compared to diesel-electric engines. The most efficient system is system 3 and has a brake specific fuel consumption of 0.08902 kg kWh-1, whereas a typical diesel-electric engine has a value of 0.2318 kg kWh-1.