(44d) Active Storage of Liquid Hydrogen

The design of an effective hydrogen storage system offers a challenging opportunity for engineers due to the low density of hydrogen. Currently available technologies include storage of hydrogen as compressed gas, cryogenic liquid and metal hydride (adsorbed hydrogen). One avenue leading to high hydrogen densities is the use of liquid hydrogen either at atmospheric or even high pressures. The critical temperature of hydrogen however is 33.2 K, and thus liquid hydrogen storage requires a well-insulated storage vessel, with a significant fraction of the total vessel volume occupied by insulation. When storage space and/or time are design considerations, as is the case for long-term storage or fuel storage on vehicles, alternatives are sought that make the most effective use of the available volume.

In this work, we propose the use of a conduction-cooled, refrigerated storage vessel for liquid hydrogen, as an alternative that can allow a reduction in the thickness of the vessel's insulation and can extend storage times by directing the in-leak heat towards a refrigerated cold sector in the insulation of the vessel. This heat is conducted through a copper layer incorporated in the insulation. Directing the heat towards the cold sector in the insulation of the vessel maintains the hydrogen in a liquid state, thus preventing evaporative losses, albeit at the cost of running the refrigerator. A basic design for a conduction-cooled liquid hydrogen storage vessel is proposed and a detailed numerical simulation of heat transfer in such a vessel is carried out.