Need help Surface Temperature Increase due to Sun Loading
Need help Surface Temperature Increase due to Sun Loading
(OP)
Assuming worst case; the military 99-percentile, the standard value is 1120 W/m^2. Surface is painted white so, the radiation absorpity is 0.14. What is the temperature increase on the surface? Assuming the object is at ambient temperature.





RE: Need help Surface Temperature Increase due to Sun Loading
> Air temp
> Wind speed
> Radiative background temperature
> emissivity
You can pretty much get anything from 82°C up to 200°C, depending on your assumptions
TTFN
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RE: Need help Surface Temperature Increase due to Sun Loading
Assume worst case, so no wind and direct sunlight-no shade.
Box is stored outside at 110F, relative humidity 70%-worst case.
Use stainless-301, assume 0.5 emissivity.
I need the formulas and source to change variables and compute the different temperatures.
thanks
RE: Need help Surface Temperature Increase due to Sun Loading
TTFN
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RE: Need help Surface Temperature Increase due to Sun Loading
I used the example on page 577. I assumed no wind so the h value is 0, alpha for white = .26, e for white =.9. sky temp = 60 deg C, qsolar = 1120 w/m^2.
Calculated 93 deg C. Sounds right?
thanks
RE: Need help Surface Temperature Increase due to Sun Loading
RE: Need help Surface Temperature Increase due to Sun Loading
Luckily, MIL-HDBK-310 claims the maximum solar load only exists for about 2 hrs a day, so, it might be possible that a transient analysis would show a slightly lower surface temp than calculated.
Your internal temp cannot be lower than your box's surface temp, otherwise, heat will flow INTO the box from the outside to compensate. If additional heat is being generated inside the box, then the interior temperature MUST be higher than the surface temperature.
TTFN
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RE: Need help Surface Temperature Increase due to Sun Loading
RE: Need help Surface Temperature Increase due to Sun Loading
thanks
RE: Need help Surface Temperature Increase due to Sun Loading
Should be solvable. Can you post your equation? What are you using to solve the equation?
TTFN
FAQ731-376: Eng-Tips.com Forum Policies
RE: Need help Surface Temperature Increase due to Sun Loading
RE: Need help Surface Temperature Increase due to Sun Loading
thanks
RE: Need help Surface Temperature Increase due to Sun Loading