Modelling of subcooled liquid hydrogen fueling system

Sammanfattning

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