How radiation affects to structure design temperature

[geodesia]

If we have an structure exposed to radiation from a flare, how can we consider it for design temperature purpose and in order to install expansion joints, etc...?

The problem we are facing now is a structure installed nearby a flare, where it is indicated a radition intensity equal to 15,8 Kw/ sqm (excluded solar radiation), with a air temperature of 58ºC (shade), 85ºC (exposed to the sun).
How this affect to the temeprature to be considered? Is there any equation/formula/procedure that relates both concepts?

Thanks in advance for your comments!

 

[IRstuff]

Basically, there's Planck's blackbody and Newton's cooling equations, modified as required for your application.

I'm unclear whether your 27°C rise is from solar load or flare?

TTFN

FAQ731-376

 

[geodesia]

Thanks IRStuff

I want to know if there is "easy solution" for calculating temperature (or temperature increment) due to radiation, when KW/sqm (Q/A) is known
27ºC rise is the data given, to be used when any element is exposed to the sun (solar radiation)
Hope more clear now?

 

[IRstuff]

OK, so you know that solar load is a maximum of about 1100 W/m^2 at sea level.

So, you have one correlation between load and temperature. I'll let you draw your own conclusions about the second load.

TTFN

FAQ731-376

 

[IRstuff]

However, it will be less than linear, since re-emitted radiation goes as the absolute temperature to the 4th power.

TTFN

FAQ731-376

 

[prex]

A flare is a point source and the power per unit surface varies with the square of the distance. Hence, unless your structure fully surrounds the flare at uniform distance, it seems improper to have a single value for the emitted radiative power.
It is also unclear whether your value is an emitted power or an absorbed one. If it is emitted, you need to scale down that value by the emissivity of the surfaces of your structure (however possibly close to 1). By this scaling down your value could come closer to a reasonable one, otherwise, with the procedure suggested by IRstuff, you could get an unreasonable temperature.
Also, as a consequence of my first sentence above, it is very unlikely that the whole structure will be uniformly heated by the flare (by contrast to solar power, that's essentially uniform), and this could change dramatically the calculated temperature.
Even if you are looking for the highest hot spot temperature (e.g. to determine an allowable stress), you could account for conduction in the structure from the hot spot to colder regions, and this also could help a lot in reducing the temperature.

prex

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