night time cooling with radiant panels, useful links

Re: solar heat - Solar Cooling - radiant energy transfer
    Posted by: "sunfarmermark" mark.dows.email@gmail.com sunfarmermark
    Date: Tue Aug 20, 2013 7:00 am ((PDT))

This is a great thing for us to be discussing and doing some experiments.  When I looked into this, I found like most solar thermal "technologies", humans have been doing this for years.  There is evidence that the Persians made ice using radiative cooling. 

There is a some good information on radiative night sky cooling at these links. 
http://misfitsarchitecture.com/2013/03/01/its-not-rocket-science-5-night-sky-radiant-cooling/
http://www.asterism.org/tutorials/tut37%20Radiative%20Cooling.pdf
http://www.erc.uct.ac.za/jesa/volume16/16-2jesa-dobson.pdf

BTW, there is another "technology" for cooling your house via the power of the sun called Katabatic cooling towers (or simply solar cooling towers).

Here are some links that describe this technique and provides examples of use:
http://en.wikipedia.org/wiki/Solar_chimney#Passive_down-draft_cooltower
http://www.builditsolar.com/Projects/Cooling/passive_cooling.htm
http://www.carboun.com/sustainable-design/a-california-building-revives-traditional-middle-eastern-designs/

Enjoy and please share your experiments/results/design thoughts with us!

Mark

--- In SolarHeat@yahoogroups.com, "A6intruder@..." <A6intruder@...> wrote:
>
> Question about cooling:
>
> Every object emits radiant energy, the rate depends on its temperature.
> Does the rate also depend on the temperature of the environment receiving
> the energy?
>
> So a solar panel that is used to heat water during the day, could it be used
> to cool other water at night?  I assume yes, some level of cooling could be
> achieved.
>
> But here is the real question, is that energy transfer by radiant energy
> emission depend on the background temperature that is receiving/absorbing
> the radiant energy?
>
> So if you had a solar cooling panel pointed at the dark sky at night - is
> the lowest temperature that could be expected the ambient air temperature or
> could you achieve lower temperatures on the surface of the emitter since it
> is pointed at a nice dark sky.
>
> The practical goal of this discussion would be to cool water at night that
> could be used to augment the AC during the daytime.
>
> Thoughts?
>
> Thanks,
>
> Dan Nicoson
> Round Rock, TX
>