Heat Transfer with Solar Loading
Heat Transfer with Solar Loading
(OP)
Good Day to All,
I'm a bit puzzled by a phenomenon that I'm seeing during a set of CFD simulations.
As an example, Say you have an enclosure with an internal heat source that is thermally connected to this enclosure.
There is a solar load beating down on the enclosure. Simulation shows, when the object is static, the Heat source reaches 180C.
Then, with the object moving at 70 mph, the temperature due to the forced convection reduces to 150C.
Then, I decide to run the simulation without the solar load. Same scenarios, results at stationary are 165C. So a DT 15C reduction due to no solar loading, this is understandable.
What I'm really puzzled about is if I then run at 70 mph (No Solar Load), I get almost the same value as 70mph with Solar Load = 150C.
Does anyone have any suggestions as to why this maybe, as my thinking is that you should see a reduction in both instances without solar loading.
I'm a bit puzzled by a phenomenon that I'm seeing during a set of CFD simulations.
As an example, Say you have an enclosure with an internal heat source that is thermally connected to this enclosure.
There is a solar load beating down on the enclosure. Simulation shows, when the object is static, the Heat source reaches 180C.
Then, with the object moving at 70 mph, the temperature due to the forced convection reduces to 150C.
Then, I decide to run the simulation without the solar load. Same scenarios, results at stationary are 165C. So a DT 15C reduction due to no solar loading, this is understandable.
What I'm really puzzled about is if I then run at 70 mph (No Solar Load), I get almost the same value as 70mph with Solar Load = 150C.
Does anyone have any suggestions as to why this maybe, as my thinking is that you should see a reduction in both instances without solar loading.





RE: Heat Transfer with Solar Loading
RE: Heat Transfer with Solar Loading
Also, when I compare both 70mph results (with an with out loading), there is no difference
70 Mph with Solar Loading = 150C
70 Mph without Solar Loading = 150C
0 Mph with Solar Loading = 180C
0 Mph without Solar Loading = 165C
RE: Heat Transfer with Solar Loading
RE: Heat Transfer with Solar Loading
Correct, there is about 0.4 Degrees C difference
But, when I look at the value of stationary, we get 180C with Solar Load, and 165C with out solar load, so that's a DT of 15C.
Then, at 70mph, we get results of 150C with Solar Load, and 149.6C with out solar load. Would it not be in the order of a similar value to the stationary results, as you could interoperate that the solar loading applies a 15c DT load?
RE: Heat Transfer with Solar Loading
But, you do not say what the actual POWER level is nor how much area is actually loaded. This results in a loaded question with no obvious answers.
> What area?
> What ambient temperature?
> What power?
> What solar load?
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
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RE: Heat Transfer with Solar Loading
RE: Heat Transfer with Solar Loading
RE: Heat Transfer with Solar Loading
Assume an outer skin temperature of 150°C.
Calculate heat transfer rate for forced convection with Q = h A (150°C- Tambient)
Now calcualte radiant heat transfer rate with Q = σ A F ((150°C)4 - (Tambient)4)
My guess is that the forced convection is much higher than the radiation heat transfer.
RE: Heat Transfer with Solar Loading
RE: Heat Transfer with Solar Loading
Try 0 mph wind.
2 mph, 5 mph, and 10 mph.
Look at your units too! Seriously, temperatures and heat loads in metric, and winds in miles per hour? Sure it doesn't think you have meters/hour? Wind speed should be meters/second, but just perhaps knots. (Nautical miles per hours)
RE: Heat Transfer with Solar Loading
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers