Pavement Temperature rise
Pavement Temperature rise
(OP)
Hi,
I have to estimate the temperature rise of an air strip (ashphalt pavement) in the Saharian desert knowing tha the sun provide around 1400 watts per square meters. The purpose is to verify what type of ashphalt to use with Boing 747 (400 tons).
Is there a way to have a good approximation for this?
Thanks
I have to estimate the temperature rise of an air strip (ashphalt pavement) in the Saharian desert knowing tha the sun provide around 1400 watts per square meters. The purpose is to verify what type of ashphalt to use with Boing 747 (400 tons).
Is there a way to have a good approximation for this?
Thanks





RE: Pavement Temperature rise
In any case, you'd equate the solar illuminance to the convective, radiative, and conductive heat loss mechanisms, and the result is totally dependent on the assumptions you make. Nonetheless, you can show mathematically, and anecdotally, that the tarmac can get up to the boiling point of water, at least, for about a couple hours a day.
TTFN
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RE: Pavement Temperature rise
h
Temperatures of over 65 deg C were measured in Saudi Arabia
http://w
You can probably find lots of measured data, may not need to estimate it unless the design has some unusual features.
RE: Pavement Temperature rise
In any case, you'd equate the solar illuminance to the convective, radiative, and conductive heat loss mechanisms, and the result is totally dependent on the assumptions you make. Nonetheless, you can show mathematically, and anecdotally, that the tarmac could exceed the boiling point of water, at least, for about an hour a day, using a lumped-element Mathcad model.
TTFN
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RE: Pavement Temperature rise
HTH
RE: Pavement Temperature rise
RE: Pavement Temperature rise
http://en.wikipedia.org/wiki/Boeing_747-400
TTFN
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RE: Pavement Temperature rise
Thanks for all the replies.
I know that this seems to be a high value. I've been told it was way too high. But in Tamanrasset, where I was in 2004, a VAG/PNUE meteo station part of a network around the world is measuring in continue solar radiation, direct, global, diffuse and RG8 (I have no clue what that mean). They gave me a 1400 W/m2 value.
The airfield I'm working on now is on a hotter part of the Sahara, reaching 55°C during summer. I was there a month ago and it was 47. Very hot... But there is no measure for that area.
For the B747-400, Boeing manual state a Max Design Takeoff Weight of 875000 pounds for the B747-400 Freighter and 910000 pounds for the 747-400ER.
A lot of weight on hot asphalt.
RE: Pavement Temperature rise
How about using concrete, rather than a bitumous asphalt?
RE: Pavement Temperature rise
RE: Pavement Temperature rise
With the assumptions I made, 1400 W/m^2 results in 120°C surface temperature.
Link below is to PDF of the Mathcad sheet I used.
TTFN
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RE: Pavement Temperature rise
In Tamanrasset, we couldn't pick up a peice of metal left under the sun. It would burn your hand.
Many thanks for your help.
RE: Pavement Temperature rise
RE: Pavement Temperature rise
On top of the sheet you find °C=K
RE: Pavement Temperature rise
RE: Pavement Temperature rise
I try to avoid using the defined degree Celcius in my sheets, since it takes a bunch of keystrokes to create the symbolically pleasing °C.
So, that's why the absolute temperatures required for the blackbody radiation equation use the delta temperature plus 273 K (and yes, I dropped the 0.15K because I was lazy).
Obviously, this isn't my day job, but it's something I can understand enough to be dangerous, and these problems are particularly well-suited to Mathcad's solver function.
TTFN
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