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Simple thermal radiation situation yields very different result from black body equation!?

ptc-4266881
4-Participant

Simple thermal radiation situation yields very different result from black body equation!?

The result for the steady-state temperature (modeling it numerous different ways) is consistently T=364 K. But the result according to Power=s*e*A*T^4 should be T=314.63 K when I use:

A=Area=1m^2 (modeled as a solid or as a surface sphere using shell elements)

e=emissivity=1.0

Power=power generated within Sphere= 1000W

 

The assumption is this is a sphere in space that does NOT have any solar flux adding heat to it.

Why is the answer so different from theoretical? I'm needing to use thermal radiation for the first time for some space equipment and am wondering whether there is a way to do things that will yield correct results for radiation. 

 

Thanks.

 

I am using Creo 11.0

1 ACCEPTED SOLUTION

Accepted Solutions

4 REPLIES 4

 

calc_t.png

ptc-4266881
4-Participant
(To:skunks)

OMG! I freaking got the answer out of a physics book solved problem (to test my ability to set-up the problem in Creo). I can’t check now but if they did their math wrong it’ll blow my mind. I will look shortly but I’m willing to accept you got it right for now. Thanks so much because I was completely bamboozled how Creo would get that wrong.

Once I’ve confirmed I’ll go on the site again and reply and confirm you got it right.

Thank you.

So check out this screenshot from the text book. Who’d o’ thunk their math was wrong?! But I used MathCAD as well and got the same answer you did. Wow. Thanks. Mystery solved.

ptc4266881_3-1716517191604.png

 

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