Slush hydrogen

<p>Slush hydrogen is a combination of <a href="/facts/Liquid_hydrogen/Vpk3Gb8P">liquid hydrogen</a> and <a href="/facts/Solid_hydrogen/TMCKnUGg">solid hydrogen</a> at the <a href="/facts/Triple_point/Npary634">triple point</a> with a lower temperature and a higher density than <a href="/facts/Liquid_hydrogen/Vpk3Gb8P">liquid hydrogen</a>. It is commonly formed by repeating a freeze-thaw process. This is most easily done by bringing liquid hydrogen near its boiling point and then reducing pressure using a vacuum pump. The decrease in pressure causes the liquid hydrogen to vaporize/boil - which removes latent heat, and ultimately decreases the temperature of the liquid hydrogen. Solid hydrogen is formed on the surface of the boiling liquid (between the gas/liquid interface) as the liquid is cooled and reaches its triple point. The vacuum pump is stopped, causing an increase of pressure, the solid hydrogen formed  on the surface partially melts and begins to sink. The solid hydrogen is agitated in the liquid and the process is repeated. The resulting hydrogen slush has an increased density of 16–20% when compared to liquid hydrogen. It is proposed as a <a href="/facts/Rocket_fuel/IyFhQEA2">rocket fuel</a> in place of liquid hydrogen in order to use smaller fuel tanks and thus reduce the <a href="/facts/Dry_weight/Cl8KLRml">dry weight</a> of the vehicle.
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Slush hydrogen open-in-new

Slush hydrogen