this post was submitted on 23 Jun 2024
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Solarpunk technology

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DIY Supermaterial Could Save You From Heatstroke: Salt based PCMs (www.youtube.com)
submitted 5 months ago by RoboGroMo@slrpnk.net to c/technology@slrpnk.net
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A simple mix of two cheap salts, Sodium Sulfate and Table Salt (Sodium Chloride) dissolved in boiling water can create a really useful Phase Change Material that has a melting point of 18c (65f) which allows it to be recharged back into it's cooling state simply by putting it in a basement and can then be used as a cooling blanket, back rest, neck pillow, etc to help keep you cool in hot weather. Longer lasting and less energy intensive to charge than an ice-pack.

In the video he talks about the potential for using a similar higher temp PCM behind solar panels to reduce efficiency loss or damage from over heating. It could also be a really interesting thing to use for transporting heat from where it's unwanted to where it's needed.

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[โ€“] ProdigalFrog@slrpnk.net 16 points 5 months ago (1 children)

@Longpork3@lemmy.nz wrote down the recipe here.

1.2l water

240ml sodium sulfate

60ml sodium chloride

20ml xantham gum(optional for increased efficacy by keeping the solution homogenous)

Boil water, stir until fully dissolved, a small amount of solute should remain, if not, increase sodium sulfate concentration slowly until it does, indicating no free water molecules available for dissolution.

Solution should now be cooled to below 18c( freezing point) for an end product that will regulate temperature to 18c so long as it have sufficient(negative) thermal energy.

Solution of pure sodium chloride will have freezing point approx -20C, while solution of pure sodium sulfate has freezing point +35C. Adjusting the ratio of NaCl to Na2SO4 will shift the freezing point towards either end of thag spectrum, depending on what phase change temperature you are targetting.