Problem 3. The inner and outer surfaces of a 30-cm-thick wall in summer are maintained at 27 C and 44 C, respectively. The outer surface of the wall exchanges heat by radiation with surrounding surfaces at 41.C, and convection with ambient air also at 41 C with a h=8 W/m2.K (convection heat transfer coefficient). Solar radiation is incident on the surface at a rate of 150 W/m2. If both the emissivity and the solar absorptivity of the outer surface are 0.8, determine the thermal conductivity of the wall. (20 points) 4x 150 W/m2 27.C 44.C as = 8 = 0.8 air and surroundings, 40.C h = 8 W/m2.K