The spectral absorptivity of a large diffuse surface is ????=0.850 for ??<1???? and ????=0.25 for ???1????....

The spectral absorptivity of a large diffuse surface is ????=0.850 for ??<1???? and ????=0.25 for ???1????. The bottom of the surface is well insulated, while the top may be exposed to one of two different conditions.
(a) In case (a) the surface is exposed to the sun, which provides an irradiation of ????=1200 W/m2, and to an airflow for which T = 300 K. If the surface temperature is Ts =320 K, what is the convection coefficient associated with the airflow?
(b) In case (b) the surface is shielded from the sun by a large plate and an airflow is maintained between the plate and the surface. The plate is diffuse and gray with an emissivity of ????=0.8. If ???=300 K and the convection coefficient 30 W/m2K, what is the plate temperature Tp that is needed to maintain the surface at Ts =320 K?
(c) in case (b) the large surface and the plate both have a dimension of 8m by 8m, and the separation distance is 2m. The other conditions remain the same. What would be the plate temperature that is needed to maintain the surface at Ts=320K?

Expert Solution

samet mamat answered 2 years ago

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