A horizontal, opaque surface at a steady-state temperature of 80°C is exposed to an airflow having a free stream temperature of
25°C with a convection heat transfer coefficient of 20 W/m2 ·K. The emissive power of the surface is 628 W/m2 , the irradiation is 1380 W/m2 , and the reflectivity is 0.30.
Determine the absorptivity of the surface.
Determine the net radiation heat transfer rate for this surface. Is this heat transfer to the surface or from the surface?
Determine the com-bined heat transfer rate for the surface. Is this heat transfer to the surface or from the surface?
Determine the absorptivity of the surface.
Determine the net radiation heat transfer rate for this surface. Is this heat transfer to the surface or from the surface?
Determine the com-bined heat transfer rate for the surface. Is this heat transfer to the surface or from the surface?
1 answer:
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Answer:
<u><em>To answer this question we assumed that the area units and the thickness units are given in inches.</em></u>
The number of atoms of lead required is 1.73x10²³.
Explanation:
To find the number of atoms of lead we need to find first the volume of the plate:
<u>Where</u>:
A: is the surface area = 160
t: is the thickness = 0.002
<u><em>Assuming that the units given above are in inches we proceed to calculate the volume: </em></u>
Now, using the density we can find the mass:
Finally, with the Avogadros number () and with the atomic mass (A) we can find the number of atoms (N):
Hence, the number of atoms of lead required is 1.73x10²³.
I hope it helps you!