Liquid Hydrogen Pool Evaporation Above Four Different Substrates

In the frame of the EC-funded project PRESLHY ten experiments on LH2-pool evaporation above four different substrates have been performed with the POOL-facility on a free field test site. Substrates to be investigated comprised concrete, sand, water and gravel. Four of the experiments were made with artificial side wind of known direction and known velocity to investigate the influence of side wind on hydrogen evaporation and cloud formation above the LH2-pool. The POOL-facility mainly consists of an insulated stainless-steel box with the dimensions 0.5 x 0.5 x 0.2 m³ that is filled up to half the height (0.1 m) with the respective substrate and LH2. The height of the LH2-pool that forms above the substrate can be determined using the weight of the complete facility, which is positioned on a scale. Additionally, six thermocouples are located in different heights above the substrate surface to indicate the LH2-level as soon as they are covered with LH2. Further measurement equipment used in the tests comprises temperature measurements inside the substrate and several thermocouples in the unconfined space above the pool, where also H2-concentration measurements were performed. Using the sensor information, pool evaporation rates for the different substrates were determined. The temperature and concentration measurements above the pool were mainly used to define promising ignition positions for subsequent combustion experiments, in which the LH2-spills above the different substrates were ignited.