Numerical Study of the Fuel Efficiency and the Thermal Management of a Fuel Cell Powered Long-Haul Vehicle

In the future, conventional powertrains will increasingly be supplied by sustainable energy sources. Long-haul freight transport requires efficient energy storage and the ability to refuel quickly. For this reason, hydrogen-powered PEM fuel cells are being discussed as a future energy source for long-distance vehicles. However, there are numerous challenges in packaging, system cooling and service life. Above all, the dissipation of the fuel cell’s heat losses places high demands on the design of the cooling system due to the relatively low operating temperature. In the presented study, a complete generic drive train of a long-distance commercial vehicle was set up within a suitable simulation environment to investigate the required sizes of the fuel cell stack, the HV battery, the hydrogen tanks, and the cooling circuit. The thermodynamic and electrochemical data that was necessary to describe the stack, the BoP components, the battery, the coolers, and the drivetrain components were taken from the literature or similar applications. Afterward, the requested propulsion power, fuel consumption, and cooling demand were analyzed for constant vehicle speed and representative driving cycles. Mountainous highway passages, as typically occurring in the Alpes, were investigated for different ambient temperatures. Detailed loss analyses were carried out for the whole powertrain and visualized in Sankey diagrams. The results revealed challenging thermal management at high ambient temperatures that may result in degrading fuel cell power when crawling uphill with low vehicle speed. However, the potential and suitability of PEM fuel cells for sustainable long-haul transport could be clearly demonstrated.