LH2 pool tests started

Last week on Friday 20th March and on Tuesday 24th March the first unignited pool tests with LH2 have been conducted. The first tests were done with a 0.5 m x 0.5 m pool with a maximum fill height of 0.1 m and a massive concrete bottom plate. So, the maximum inventory of the pool is 1.75 kg LH2.

They were showing some interesting phenomena:

  • The thin alumina sheets were slightly bended due to thermal shock / stresses.
  • There were wave like oscillations, partly attributed to the LH2 surface (which was hardly visible) and partly to cold hydrogen vapour/ water fog and ambient air interface (with smaller frequency).
  • There is a high frequency oscillation heard (about 5-8 kHz) in the initial phase when the cryovalve is opened (similarily observed also when opening LN2 tanks).
  • The heavy evaporation generated huge fog clouds which are deemed to coincide with flamable envelop.
  • The almost steady pool evaporation rate was 10 g /s, corresponding to 1/7 liter / s or 3.43 cm / min.
  • The pool and the release nozzle show a very homogeneous ice layer after the experiment, when LH2 is completely evaporated. It is asssumed that this is water ice.

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