Thermodynamic Modeling of Hydrogen Refueling for Heavy-duty Fuel Cell Buses and Comparison with Aggregated Real Data

The foreseen uptake of hydrogen mobility is a fundamental step towards the decarbonization of the transport sector. Under such premises, both refuelling infrastructure and vehicles should be deployed together with improved refuelling protocols. Several studies focus on refuelling the light-duty vehicles with 10 kgH2 up to 700 bar, however less known effort is reported for refuelling heavy-duty vehicles with 30–40 kgH₂ at 350 bar. The present study illustrates the application of a lumped model to a fuel cell bus tank-to-tank refuelling event, tailored upon the real data acquired in the 3Emotion Project. The evolution of the main refuelling quantities, such as pressure, temperature, and mass flow, are predicted dynamically throughout the refuelling process, as a function of the operating parameters, within the safety limits imposed by SAE J2601/2 technical standard. The results show to refuel the vehicle tank from half to full capacity with an Average Pressure Ramp Rate (APRR) equal to 0.03 MPa/s are needed about 10 min. Furthermore, it is found that the effect of varying the initial vehicle tank pressure is more significant than changing the ambient temperature on the refuelling performances. In conclusion, the analysis of the effect of different APRR, from 0.03 to 0.1 MPa/s, indicate that is possible to safely reduce the duration of half-to-full refuelling by 62% increasing the APRR value from 0.03 to 0.08 MPa/s.