This article investigates the potential of the energetic utilization of hydrogen expansion in a fuel cell electric vehicle (FCEV) as pressure decreases from 700 bar in the H2 storage to approximately 5 bar in the fuel cell stack. The article focuses on the boundary conditions of passenger and heavy-duty vehicles, which are analyzed and evaluated by means of simulations. The expansion process is evaluated from the thermodynamic side with assumptions of an isothermal and isentropic process.

The power required for heating, ventilation and air-conditioning (HVAC) of the passenger compartment in BEMU strongly affects the capacity and lifetime of the battery. Accordingly, 11 different measures for reducing the energy demand of HVAC are presented in this paper. The measures are investigated using Dymola models of a thermal car body to determine the energy saving potential as well as the effects on the vehicle. Reducing the amount of fresh air while complying with CO₂ limits and using a heat pump are efficient measures to reduce the annual energy demand for the HVAC system by 62% or 48%, respectively. In addition, a control-based, catenary dependent HVAC operating strategy is being developed that decisively reduces the load on the battery during dynamic operation. This approach is particularly suitable for straightforward implementation since no design changes to the vehicle are necessary.

Battery-electric rail vehicles are a sustainable alternative for diesel-powered vehicles on tracks without catenary. However, the energy demand to heat and cool the cabin limits the vehicle range, and the applied synthetic refrigerants are environmentally harmful. Therefore, this paper studies how energy demand and load on the battery in battery-electric rail vehicles can be reduced using heat pumps with natural refrigerants and efficient thermal management. A heat pump and thermal car body model are developed and validated, which calculate the energy demand in battery-electric rail vehicles. In these models, an optimized thermal management strategy is implemented, which changes the cabin set-point temperature based on catenary availability. For a two-car battery-electric rail vehicle in the climate zone II of Central Europe, the annual thermal energy demand is up to 110 MWh. The application of a heat pump with R290 (propane) can reduce the annual electrical energy demand for heating and cooling by up to 55%. The load on the battery can be mitigated further with the optimized thermal management strategy, reducing the equivalent full cycles by 3%. Overall, the heat pump operation and efficient thermal management strategy lead to higher vehicle range and flexibility in daily operation, increasing the acceptance of battery-electric rail vehicles.

Hydrogen-powered trains present a sustainable alternative to diesel-powered trains for railway transport of passengers and freight. Hydrogen as an energy carrier is cost-intensive, which is why energy demand should be reduced in all relevant operational scenarios. Since thermal losses are one of the main reasons for efficiency reductions, the presented work investigated the research question: Can hydrogen-powered trains combined with targeted energy management strategies be simulated and potential energy efficiency gains be quantified for European and North American scenarios? A digital railway vehicle simulation framework is developed, which models longitudinal dynamics and energy management. The framework is built with standardized functional mock-up interfaces (FMI) for component sub-models to enable a co-simulation with models from different entities. As input for the simulations, different passenger and freight transport scenarios from Europe and North America are used. Requirements for hydrogen-powered trains vary greatly for different use cases of passenger and freight transport, as well as the location with its surrounding climate. Recuperation of braking energy in freight transport is challenging and remains an opportunity for further enhancement. For passenger transport, metal hydride cooling systems can provide additional cooling capacity and reduce electrical energy demand for air conditioning.