Using a solar oven as a radiant refrigerator at night
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Using a solar oven as a radiant refrigerator at night
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Re: Using a solar oven as a radiant refrigerator at night
#2I’m missing the basic premise here, how does pointing an insulated box at the sky at night cool whatever’s in the box?
Re: Using a solar oven as a radiant refrigerator at night
#3I’m missing the basic premise here, how does pointing an insulated box at the sky at night cool whatever’s in the box?
I'm guessing he just froze water when the temperature dropped below zero at night, and everything else is nonsense.
Re: Using a solar oven as a radiant refrigerator at night
#4Cool. Might be able to do even better with self-cooling paint [0,1] during the day to reject heat and Vantablack [2] at night to radiate it? (although I wonder how Vantablack would do at radiating with its microstructured surface)
[0] https://www.parc.com/technologies/self-cooling-paint/
[1] https://www.purdue.edu/newsroom/releases/2021/Q2/the-whitest...
[2] https://www.abc.net.au/news/science/2017-01-13/vantablack-wh...
Re: Using a solar oven as a radiant refrigerator at night
#5I’m missing the basic premise here, how does pointing an insulated box at the sky at night cool whatever’s in the box?
Almost all surfaces radiates heat. You can heat and cool using radiation. It’s the same way satellites is cooled, when you can’t cool with convection (interact with other atoms).
Black absorb more radiation, but it also radiates more
Re: Using a solar oven as a radiant refrigerator at night
#6I’m missing the basic premise here, how does pointing an insulated box at the sky at night cool whatever’s in the box?
I guess that not having other warm objects pointing at the water, will not warm the water (example: a wall radiates infrared so it heats the water if the wall has "sight" over the water).
Insulating the walls of the container with the water servers the same purpose - not have the water get heat from the surroundings.
Re: Using a solar oven as a radiant refrigerator at night
#7I’m missing the basic premise here, how does pointing an insulated box at the sky at night cool whatever’s in the box?
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.
Re: Using a solar oven as a radiant refrigerator at night
#8I’m missing the basic premise here, how does pointing an insulated box at the sky at night cool whatever’s in the box?
A black body will emit radiation (and receive radiation) until it's in equilibrium with its surroundings. In theory, the black bit of box radiates heat into space, and receives some of the CMB until both are at ~3K. It's how we cool satellites and spacecraft.
But the effect is quite small, and I'm suspicious of it (as the nearest surroundings are the hot planet, which transfer heat more effectively!)
Re: Using a solar oven as a radiant refrigerator at night
#9I’m missing the basic premise here, how does pointing an insulated box at the sky at night cool whatever’s in the box?
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Re: Using a solar oven as a radiant refrigerator at night
#10It’s good for a couple degrees I think you can get water to freeze at 36 on a clear night for example