1 Liquid Hydrogen R&D test report Video Conference – 23/08/12 S Watson P Warburton M Courthold

Test programme Stated aim to produce 22 litres of LH2 1.Hydride bed charge 2.H2 fill x 3 3.H2 empty x 3 4.Hydride bed empty 2

Bottle ‘incident’ Small leak from H2 bottle when connecting Fixing resulted in a brief but rapid release…vent system went above LEL All procedures, alarms and interlocks worked as expected! 3

Hydride bed charge Manufacturer suggested 8 hour charge Started with heater-chiller at -15°C Connected 2 H2 bottles (~16000l) Regulator set to 1.5 bara No flow meter in line so only indicator of progress was bottle pressure Dropped to <10 bar in ~2 hours 4

First H2 fill Commenced fill at 3am on 30 th July Cooldown rapid – pressure control loop started after 16 hours Hydride bed back pressure dropped faster than expected... …and heater loop did not initiate Hydrogen began to freeze Fill aborted 5

6 Bed pressure starts to drop H/C temp increased Control valve stays open Hydrogen starts to freeze

Second H2 fill Restarted without empty sequence Manual control of heater and hydride bed temperature Reached 10,000 litres of H2… …equated to approx 12 litres of LH2 No graph…control system reset and overwrote data! 7

Empty sequence Sequence uses heater to boil off LH2 and return to hydride bed Very conservative starting conditions, gradually ramped up LH2 boil-off completed in approx 15 hours 8

9 Pressure setpoint changed LH2 all boiled off

Final H2 fill Automatic control of heater Manual control of hydride bed temp Realised that HX temperature must be lower than expected to condense Optimised setpoint resulted in steady condensation rate Heaters are critical when H2 flow slows 10

11 Hydride bed temp increased Hydride bed temp maxed H2 flow beginning to slow; heater loop now critical

Hydride bed empty Purge of gas panel with helium Set hydride bed to max temperature and pumped directly on it After approx 12 hours, pressure was around 100 mbar Filled with argon to 3 bar and closed hand valve = back to original state 12

Outcomes Cryogenic efficiency is good Control system largely debugged Temperature control Heaters critical when H2 flow slows Hydride bed needs more instrumentation Successful characterisation of major system components Optimisation will come with AFC (different instrumentation) 13