Design methodology for a PEM fuel cell power system in a more electrical aircraft

In recent years the concept of ‘‘more electric aircrafts” has established itself increasingly and the electri- cal power systems for aircrafts are in progress. In this context, fuel cells represent a valid source of elec- tric power for the advantages in terms of pollution emissions, noise reduction and fuel consumptions. In this study, the authors analyzed the feasibility, from the specific energy point of view, in using a PEM fuel cell power system as APU unit in a more electrical aircraft with respect to a battery system installa- tion. The proposed fuel cell system has a modular architecture and consists of fuel cell stacks, air com- pressors, heat exchangers, compressed hydrogen tanks and auxiliary batteries. The analysis has been performed by applying a design methodology based on an optimization proce- dure concerning the size and the efficiency of each power system component in order to reach the max- imum specific energy (higher than 500 W h/kg). Moreover, a ‘‘black-box”-type model of the power system has been developed to support the optimiza- tion methodology in the evaluation of its performance in terms of electric power production, heat pro- duction, auxiliary systems consumption and hydrogen consumption. Results pointed out the advantages of the PEM fuel cell application in a more electric aircraft; as a mat- ter of fact for assigned mission requirements, according to the specifications defined in the Long Endurance Demonstrator (LED) project promoted by CIRA (Italian Aerospace Research Centre), the speci- fic energy of the designed power system results to be equal to 0.51 kW h/kg. This value is very interesting if compared to the specific energy of commercial LiPo batteries characterized by 0.2 kW h/kg.