PhysiCal Analysis of evaPoration and sloshing phenomena in LH2 transport tanks – CAPLH2

Hydrogen as a source of energy is massively investigated by car constructors and has always been a subject in rocket design. The transport of medium to large-scale hydrogen vessels is conducted in its liquid form at low temperature (20K) for energy efficiency. LH2 is stored in super insulated tanks to greatly reduce its heating during transportation. However, vaporization of H2 still occurs inside the tank due to the unavoidable heat flux coming from the reservoir wall. The vaporization causes an increase of the internal reservoir pressure. The vessel self-pressurization is avoided by releasing the vapor, causing a H2 loss of 2 to 3% per day. This phenomenon is called boil-off in the literature and is considered as a stumbling block to resolve to promove the use of liquid hydrogen as an efficient and reliable source of energy.

The aim of this project is to study the vaporization phenomenon occurring in liquid hydrogen storage tanks subject to sloshing during transportation with high fidelity direct numerical simulations. Our goal is to provide physical insights into such processes together with some outcomes of practical relevance to predict and optimize the evaporation rate and the self pressurization of LH2 vessels.

This young researcher project is articulated in two main tasks. The first is to perform a parametric study of the influence of the sloshing phenomenon on the liquid-gas interface in an isothermal configuration and to quantify the amount of average surface density in the reservoir. From these results, scaling laws allowing the prediction of the surface quantity as a function of the most influential adimensional numbers will be proposed. The second task is dedicated to the study of the same reservoir but this time with phase change. A strong sloshing of the reservoir will generate a large amount of surface, promoting the evaporation of LH2 and encapsulation of gaseous structures. A parametric study will also be carried out to highlight the most important dimensionless numbers and to propose scaling laws and adapted models to be able to predict the rate of vaporization in real tanks.