Internal air temp of an aluminum box with solar loading

[jt783]

Hi all,

I’ve seen a few other posts about this but many have internal power generation


Lets say I have a large aluminum box, 10m x 10m x 10m that is completely sealed. If each side (except the bottom) if subjected to 500w/m^2 of solar loading. How much hotter will the internal air get? Is more information needed to solve the problem?

I assume there is no air movement between the inside and outside box.

 

[IRstuff]

Bare aluminum? Air temp?

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[MintJulep]

How much hotter than what?

This looks useful.

https://www.heatsinkcalculator.com/enclosure_temperature_rise_calculator.html

 

[LittleInch]

Also it's physically impossible for each side of a cube to be exposed to solar radiation at the same time.

This acts to limit the temperature as at least one side will be emitting heat via convection and radiation.

Also if its completely sealed it will increase in pressure - maybe not much but on a 10m x 10m side it will be significant.

"Black body" temperature is rarely notified above 80C so with a nice shiny surface it might be les sor actually might be more as it doesn't emit radiation heat in the same way. The air temp won't be able to get higher than the metal surface temperature and given other inefficiencies and cooling I would estimate about 60-65C.

How accurate do you need?



Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[hacksaw]

500w/m2 is a bit low, what is the latitude?

You need to allow for at least three times that. In the middle east you have to allow for 85C surface temperatures.

LI is absolutely correct, low emissivity surfaces get hotter than you might expect, hot enough to cause 2nd/3rd degree burns with metal surfaces lacking and cooling or heat vents.

 

[IRstuff]

The maximum solar load per MIL-HDBK-310 is 1120 W/m^2, and the solar constant at the edge of the atmosphere is 1364 W/m^2

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[itsmoked]

What are you trying to do with this box? Just storage?

Keith Cress
kcress -

http://www.flaminsystems.com

 

[itsmoked]

Don't forget a box like you suggest is a water pump or AWG (Atmospheric Water Generator). It will cycle so rapidly daily that it will condense water out of the air every single day, then steam everything inside each morning, driving some nasty corrosion processes on metals and horrid mildew issues on organics including vagrant dust.

Keith Cress
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http://www.flaminsystems.com