Modelling of subcooled liquid hydrogen fueling system

Abstract

In order to reduce greenhouse gas emissions in the transportation sector, hydrogen is recognized as a promising fuel alternative, particularly for heavy-duty applications where high energy density is required. Subcooled Liquid Hydrogen (sLH2) is of significant importance due to its superior volumetric energy density and higher mass flow rates, outperforming compressed gaseous hydrogen in terms of rapid and high-capacity refuelling. However, challenges related to refuelling duration and storage capacity must be addressed, especially for heavy-duty vehicles requiring large hydrogen quantities. The initial thermodynamic state of the tank and the State of Charge (SoC) at the time of refuelling significantly dictate the maximum mass of hydrogen that can be effectively stored. The objectives of this thesis are to investigate the sLH2 refuelling system to determine the optimal initial conditions for truck tanks and to identify other critical factors influencing the process. Furthermore, the thermal behavior and pressure dynamics of sLH2 during refuelling and storage are complex phenomena that require advanced numerical modelling for system optimization. Given its capability for 1D CFD and its reliability in vehicle system simulation, GT-SUITE was selected as the modelling tool to allow for rapid and accurate analysis. Initially, the refuelling system was modeled and validated. Subsequently, the defuelling process was modeled to determine the initial thermodynamic of the tank and SoC. Finally, a sensitivity analysis was performed to identify the key parameters affecting the refuelling system’s performance. The results indicate that since the tank pressure must be maintained at a specific level due to fuel cell demand, the initial tank temperature has a predominant impact on the final hydrogen storage mass and the overall system efficiency.