Evaluation of Hydrogen Refueling Protocols from SAE J2601-5 for Railway Vehicles using Physical Simulation Models

Abstract

The deployment of hydrogen-powered rail vehicles across Europe's non-electrified networks requires validated refueling protocols that ensure safe and efficient hydrogen delivery within operational scheduling constraints. Current hydrogen refueling standards were developed primarily for automotive applications and lack validation for rail vehicle requirements, which involve significantly larger storage capacities and different operational conditions. The application of hydrogen refueling protocols to rail vehicles presents challenges related to thermal management, pressure control and achieving predictable refueling performance across varying environmental conditions. Rail vehicles require 160-320 kg hydrogen capacity with refueling completed within depot scheduling windows, demanding higher flow rates and adaptive control strategies under-represented by existing automotive-focused standards. In recent times a new standard (SAE J2601-5) was developed to address the refueling of vehicles with higher storage capacities. However, this standard is not yet fully published as it is still a TIR. Additionally, the standard only contains control parameters for the refueling process but no specific refueling times, making it difficult for vehicle operators to design timetables regarding refueling schedules. Therefore, the research objective of this master thesis is to evaluate the SAE J2601-5 MCF-HF-G protocol for rail vehicle applications by determining refueling times and final state-of-charge outcomes by systematically analyzing how ambient temperature, precooling temperature and initial state-of-charge influence refueling performance and protocol termination behavior. A lumped-parameter simulation model was developed in Dymola to implement the complete MCF-HF-G protocol equations including t_final calculation, pressure ramp rate determination criteria. The model was validated against measurement data and used to evaluate 34 parameter combinations encountered under normal operational conditions for railway vehicles with 180 kg hydrogen capacity systems. The analysis reveals that refueling times vary from 13.55 minutes to 65.45 minutes depending on operating conditions, with ambient temperature being the dominant factor. Cold conditions (-20°C ambient, -40°C precooling) enable rapid refueling but often result in early termination with final state-of-charge values as low as 47%. Warm conditions (40°C ambient, minimal precooling) extend refueling duration significantly while achieving higher final state-of-charge up to 90%. The protocol maintains safety compliance in all cases. However, the pressurebased termination approach results in variable final state-of-charge outcomes in simulation that may not meet rail operational requirements.