Sloshing Measurements inside a Liquid Hydrogen Tank with External-Heating-Type MgB₂ Level Sensors during Marine Transportation by the Training Ship Fukae-Maru

Recently, a project was initiated in Japan to transport a large amount of liquid hydrogen (LH₂) from Australia to Japan by sea. It is important to understand the sloshing and boil-off that are likely to occur inside an LH₂ tank during marine transportation by ship, but such characteristics are yet to be experimentally clarified. To do so, we combined the liquid level detected by five 500 mm long external-heating-type magnesium diboride (MgB₂) level sensors with synchronous measurements of temperature, pressure, ship motion, and acceleration during a zigzag maneuver. During this zigzag maneuver, the pressure of gaseous hydrogen (GH₂) in the small LH₂ tank increased to roughly 0.67 MPaG/h, and the temperature of the GH₂ in the small LH₂ tank increased at the position of gaseous hydrogen at roughly 1.0 K/min when the maximum rolling angle was 5°; the average rolling and liquid-oscillation periods were 114 and 118 s, respectively, as detected by the MgB₂ level sensors, which therefore detected a long-period LH₂ wave due to the ship's motion.