Speaker
Description
To ensure the safe and efficient operation of the liquid hydrogen (LH2) infrastructure, it is crucial to understand the thermodynamic processes in LH2 tanks. All LH2 tanks, both stationary tanks and tank trailers, experience pressurization due to heat inleak through their thermal insulation. The self pressurization rate over time is important for safe operation, but the complex thermodynamic phenomena involved make it challenging to develop an accurate, universally applicable model. A variety of models for this phenomenon is proposed in the literature, but only a very limited amount of experimental data, mostly from stationary LH2 tanks, is published. So far, validated models for these stationary LH2 tanks are usually based on correlations or correction factors for the heat transfer or phase transition at both the liquid-gas interface and between the tank wall and the fluid.
In this work, novel experimental data of the self-pressurization of LH2 trailers in operation is presented. The unique benefit of this pressure data arises from the fact that the phases in the LH2 trailer can be either in equilibrium, when the trailer is on the road and the phases are mixed due to the dynamic movements, or in non-equilibrium, when the trailer is parked. This allows a direct calculation of the heat inleak through the insulation, limiting the need for approximations via correlations or correction factors solely to the heat transfer and phase transition at the liquid-gas interface.
A thermodynamic model is presented in this study, based on a lumped-element method. The thermodynamic model is then validated against the novel data of the self-pressurization of LH2 trailers. The resulting validated thermodynamic model targets to be universally applicable. Together with the presented novel data from LH2 trailers in operation, the results and insights of this work support the development of accurate models of the processes in LH2 tanks required for an efficient future LH2 infrastructure.
