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Hydrogen Holders
Name: Jack
Status: student
Age: 20s
Location: N/A
Country: N/A
Date: 2000
Question:
I have check the archives about storage of liquid hydrogen but
there was no information about the material used to hold
the liquid hydrogen. My question is, what kind of material are
commonly used to store liquid hydrogen. If this was the material
used to store the liquid hydrogen, why it is better than other
materials.
Replies:
Liquid Hydrogen, L-H2, is stored in containers made of a number of
different materials depending upon how much and for how long the L-H2 must
be stored.
They all have one common characteristic -- they are poor conductors of
heat -- because L-H2 boils at 20 K, and the heat required to evaporate L-H2
is quite small. The containers have multiple concentric vessels: L-H2
surrounded by vacuum, surrounded by a jacket of liquid nitrogen, L-N2 (B.P.
= 77 K), to reduce both convective and radiative heat load, and yet another
vacuum jacket.
Only certain alloys meet the demands of L-H2 storage because they embrittle
due to the low temperature and by diffusion of H2 gas into the metal which
further makes it brittle. The vessel must also withstand the thermal
contraction that results from the low temperature -- solder joints in
particular are subject to differential expansion that creates large
stresses.
For short periods, and for short quantities (say less than 50 liters) the
inner container is sometimes Pyrex glass, because of its low thermal
conductivity and low thermal expansion. However, hydrogen diffuses into and
through Pyrex over time and causes loss of vacuum in the insulating vacuum
spaces.
Vince Calder
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Update: February 2012
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