Performance Study of Heavy-Duty Fuel Cell Electric Vehicles

This thesis work, conducted with the direct collaboration of Iveco Group, aims to evaluate the performances, intended as power, energy and heat rejection capability, of two different configurations of an Heavy Duty Fuel Cell Electric Vehicle (FCEV). The company provides the vehicle's parameters and its real component data, along with the system's longitudinal dynamic simulations over two routes that are regularly traveled by vehicles of the same size and category. These simulations give comparative results for the two configurations, which differs by the implemented fuel cell system, one having an output power availability greater than the other. The resulting data is analyzed and elaborated to evaluate the performance of the two FC systems, that affect the overall vehicle's operation. It is also analyzed the heat rejection demand of each fuel cell during the missions, through the use of the system's efficiency maps, and compared between the two configurations. The results indicate that the more powerful fuel cell system offers advantages in vehicle speed, power, and torque during high demand uphill sections of the routes. In contrast, the less powerful system presents difficulties in these sections while still allowing the vehicle to traverse them at a lower speed and generating less heat. In the second part of the thesis it has been evaluated the net available energy at the DC bus, out of the total energy on board, that is stored in form of hydrogen fuel. The net energy has a direct impact on the driving range and is compared with the one of a Battery Electric Vehicle (BEV) of the same size and category. It has been evaluated the amount of battery cells in both weight and volume that are necessary achieve the same utilizable energy on board of the FCEV, considering the currently adopted battery technology, but also a future projection of the cells' increase in energy density. The two topologies are discussed, pointing out the major challenges regarding the energy storage for Heavy Duty vehicles, such as the recharging capability and the weight and volume of the system, in which the FCEV demonstrates a significant advantage over the BEV.