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Cryogenic Boot/Helmet - External cryogenic liquid filled reinforced boot/helm

For use OVER ppe gear. Was speculating whether maybe a boot, helmet, bracers etc with built in pressurized cryogenic liquid compartments put on over any type of ppe gear- would work to cool parts of the body without compromising or altering the protective gear. Preferably an inert non toxic gas but seeing as it's in a reinforced compartment maybe ammonia could be used (NASA use ammonia) Possibly even liquid nitrogen or a similar cryogenic liquid. Cryoboot, Cryohelm, Maybe compartments that can be topped up and re-pressurized through valves similar to gas cylinder valves. One possible drawback would be the enormous pressure the liquid gas capsules would be under in order to keep the gas cold. (Sole as one compartment?)

Photo of Anthony Davis
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Another drawback is these are new and not immediately deployable but still worth looking into.

Please feel free to speculate and point out problems or solutions in the comments section, it's all helpful!


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Photo of Rainer Winkler

Hi Anthony, you would not close capsules with liquid gas. You do not keep them cold by this. What will happen is, that the temperature and pressure rise until the capsule explodes.

You allow the gas to evaporate, this keeps the liquid cool. Then you provide a good thermal insulation, so evaporation is low.

This is already proposed by NASA:

Kind regards, Rainer

Photo of Anthony Davis

What I was wondering Rainer is - if the pressure could be maintained - would the temperature stay the same/remain cold? I understand the pressures involved, it would most likely be infeasible - but in theory would it remain cold?

Photo of Rainer Winkler

Hi Antony,

it is the same like sweating. If water evaportates it requires energy, the latent heat of evaporation. This energy is taken from the liquid and cools it.

The same works with liquid cryogenic gas. Just leave the bottle open, the liquid evaporates and cools the liquid. We do this routinely in laboratories. But typically not with liquid air, but with liquid nitrogen. Liquid air is not so easy and safe to handle as liquid nitrogen, but you can get and use it, if needed.

With kind regards, Rainer