4 ms·

I'm guessing he just froze water when the temperature dropped below zero at night, and everything else is nonsense.

by mateo1 3y ago

hifikuno 3y ago
I wonder how you prove/disprove this. I imagine if you had a control box with water exposed to the air that wasn't "radiating heat," then that should show if the solar freezer was indeed working or not.
- toast0 3y ago
  You could build a few test configurations. One as stated, insulated fridge, open on top. One, insulared fridge, open on top, under an open air shelter, no walls, just a roof, where the roof is a significant distance away from the top of the fridge, so airflow is not impacted, but there's no view or the sky. Possibly variations on this with the roof being ir transparent or not. Another test configuration could have the fridge closed, but with forced air ventilation.
- tagawa 3y ago
  He did try a basic control with his first version: “i got ice consistently over several nights, even though there was no frost on the ground, and pots of water sitting next to the box cooker did not freeze.”
  - hifikuno 3y ago
    Ah you're right! I totally missed that line. Cheers.
deleted 3y ago
[deleted]
satori99 3y ago
Humans have been using this technique (radiating heat into the cold of space) to freeze water in hot places, for a very long time. https://www.realclearscience.com/blog/2018/07/09/how_people_created_ice_in_the_desert_2000_years_ago.html https://www.realclearscience.com/blog/2018/07/09/how_people_...
- mateo1 3y ago
  That's an interesting article. I'm aware of this sort of radiative cooling, but usually convection and conduction, along with evaporative cooling will be much, much more important than radiative cooling. I'd like to see some kind of report or article showing the cooling potential in W/m^2. I remember someone made a metamaterial optimized for emitting heat in the wavelength of the atmospheric window, but the value was quite low.
  - satori99 3y ago
    You might be thinking of the work led by Professor Shanhui Fan @ Stanford some years back; https://news.stanford.edu/2017/09/04/sending-excess-heat-sky/ https://news.stanford.edu/2017/09/04/sending-excess-heat-sky... This is being commercialized, but I don't know how successful it has been to date. https://www.skycoolsystems.com/ https://www.skycoolsystems.com/

I'm guessing he just froze water when the temperature dropped below zero at night, and everything else is nonsense.

by mateo1 3y ago

I'm guessing he just froze water when the temperature dropped below zero at night, and everything else is nonsense.

I wonder how you prove/disprove this. I imagine if you had a control box with water exposed to the air that wasn't "radiating heat," then that should show if the solar freezer was indeed working or not.

toast0 3y ago
You could build a few test configurations. One as stated, insulated fridge, open on top. One, insulared fridge, open on top, under an open air shelter, no walls, just a roof, where the roof is a significant distance away from the top of the fridge, so airflow is not impacted, but there's no view or the sky. Possibly variations on this with the roof being ir transparent or not. Another test configuration could have the fridge closed, but with forced air ventilation.
tagawa 3y ago
He did try a basic control with his first version: “i got ice consistently over several nights, even though there was no frost on the ground, and pots of water sitting next to the box cooker did not freeze.”
- hifikuno 3y ago
  Ah you're right! I totally missed that line. Cheers.

deleted 3y ago

[deleted]

satori99 3y ago

Humans have been using this technique (radiating heat into the cold of space) to freeze water in hot places, for a very long time. https://www.realclearscience.com/blog/2018/07/09/how_people_created_ice_in_the_desert_2000_years_ago.html https://www.realclearscience.com/blog/2018/07/09/how_people_...

mateo1 3y ago
That's an interesting article. I'm aware of this sort of radiative cooling, but usually convection and conduction, along with evaporative cooling will be much, much more important than radiative cooling. I'd like to see some kind of report or article showing the cooling potential in W/m^2. I remember someone made a metamaterial optimized for emitting heat in the wavelength of the atmospheric window, but the value was quite low.
- satori99 3y ago
  You might be thinking of the work led by Professor Shanhui Fan @ Stanford some years back; https://news.stanford.edu/2017/09/04/sending-excess-heat-sky/ https://news.stanford.edu/2017/09/04/sending-excess-heat-sky... This is being commercialized, but I don't know how successful it has been to date. https://www.skycoolsystems.com/ https://www.skycoolsystems.com/