
Renewable, electricity-free cooling and heating (for vaccines, etc) - nathandaly
https://contest.techbriefs.com/2018/entries/medical/9200
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nathandaly
Hey HN! I'm part of the team behind this device. It can keep vaccines cold
indefinitely without electricity—you only need to move the device in and out
of the vaccines container and maybe lay it in the sun once in a while. This is
a link to our design contest submission page.

It's an absorption heat-pump that uses osmosis and exo-/endothermic salts.
There's a cooling phase (absorbing heat) and heating phase (releasing it) and
it switches b/w them when it crosses a temp threshold (73°F). See diagrams in
URL.

How to use it:

Put vaccines in an insulated box (maybe cooled earlier w/ the device). Put the
pack into a stream (or already cold box), which lowers the pack's temp below
73°F and starts the runaway cooling. The pack gets cold (~40°F) in a matter of
seconds. It absorbs heat from the box and stores it as chemical potential
energy in the form of dissolved NaNO3 and crystalized CaCl2. After hours or
days, remove the pack. If outside air is above 73°F, it automatically triggers
the heating phase when it warms up to room temp. If not, manually warm it up
(lay in the sun or on the stove) to bring it above 73. Then in just minutes it
gets hot (~105°F) as the salts release all their stored heat. When heating
finishes and the pack returns to room temp, store it or put it back in the box
to start cooling again.

Principle is similar to other systems, e.g. A/C in RVs
(wikipedia.org/wiki/Absorption_refrigerator). But A) it's driven by small temp
changes you apply, so it's easier to do w/out electricity, and B) it uses safe
cheap materials.

Cooling per kg (of salt+water) is around 90% of melting ice. (ie, approx the
same weight of ice in the cooler for same amount of cooling)

\--

Big impact where spotty electricity makes storing vaccines difficult: long
electricity outages spoil vaccines, which have to be thrown away.

Another monetization: sell as electricity-free heating to backpackers.

This is part of an engineering competition. If you want to support it please
vote for us!

