A carregar...
Publicação
Liquid hydrogen thermal energy storage unit for future ESA science missions
| Nome: | Descrição: | Tamanho: | Formato: | |
|---|---|---|---|---|
| 78.39 MB | Adobe PDF |
Orientador(es)
Resumo(s)
The X-IFU instrument for X-ray observation on ESA’s new ATHENA satellite will employ
a complex cryogenic chain for detector cooling down to 50mK. The existence of heat
peaks during the recycling stages of a 300mK cooler can compromise the stability of
the entire chain; this issue can be solved by using large cryogenic liquid reservoirs or by over-dimensioning the system. However, these solutions are either costly or temporary, as cryogenic liquids will eventually run out.
An Energy Storage Unit (ESU) using liquid hydrogen has been developed as a solution
for absorbing 400 J of thermal energy in 30 min between 15K and 16K by taking
advantage of the liquid-to-vapour latent heat of hydrogen in a closed system. The ESU
is composed of a low temperature liquid hydrogen reservoir, two intermediate interfaces
for gas pre-cooling and a hydrogen storage vessel at room temperature. This vessel can either be a 56-litre expansion volume (for ground testing) or a canister filled with a metal hydride, LaNi4:8Sn0:2, that chemically absorbs hydrogen in its atomic form. The latter largely reduces the volume of the vessel and enables working at near-constant pressure and temperature.
Two devices have been developed for this project: a Development Model breadboard
device used for preliminary testing and the Engineering Model, the final model of the
ESU that is to be delivered to ESA and that was subjected to severe mechanical testing
in order to comply with strict requirements. Results obtained with both models show
that 400 J can be absorbed with a temperature increase of 2K when a 56-litre expansion volume is used, while results using metal hydrides show that the same heat load can be absorbed between 15K and 16:5K, where the cold cell temperature is above 16K for less than 10 min. Full regeneration of the ESU can be achieved in under 24 h without exceeding the cooling power available at the different temperature stages. Experimental results are discussed and suggestions for further improvement are proposed.
Descrição
Palavras-chave
Energy Storage Unit Cryogenics Metal hydrides Liquid hydrogen