A concrete wall of a cold storage room measures 3.0 m high, 5.0 m wide, and 20 cm thick
The room temperature is maintained at -10°C and the outside temperature is 20°C The inside wall is to be covered by a layer of wood in order to reduce the rate of heat loss through the wall BY 90 percent. The thermal conductivities of concrete and wood are 0.80 W/m ? K and 0.040 W/m ? K, respectively. Under steady state conditions, the thickness of the layer of wood required is closest to
A) 60 mm.
B) 70 mm.
C) 80 mm.
D) 90 mm.
E) 100 mm.
Answer: D
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