The roof of an industrial building consists of a rough concrete slab with an emissivity of 0.94, the root's dimensions o

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The roof of an industrial building consists of a rough concrete
slab with an emissivity of 0.94, the root's dimensions of roof
10×25 m and 16 cm of thickness. The convection heat transfer
coefficient of the roof is 50 W/m² K. and the thermal conductivity
of the roof is 2.5 W/m.K. On a winter night, the ambient air
temperature is -2°C, and the sky's temperature is (-23°C). The
exterior surface of the roof is at 0°C. while the temperature of
the indoor air and inner wall surface temperature 10°C.
Determine
(1) The heat transfer through the roof.
(2) The flow of exergy associated with that heat flux.
3)The rate of exergy destruction in the heat transfer by
conduction from the inner to the outer surface of the roof