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Ria) The hot combustion gases of a furnace are separated from the ambient air and its surroundings, which are at 25°C, by a brick wall 0.15 m thick (Figure 1a). The brick has a thermal conductivity of 1.2 W/m-K and a surface emissivity of 0.8. Under steady-state conditions an outer surface temperature of 100°C is measured. Free convection heat transfer to the air adjoining the surface is characterized by a convection coefficient of h = 20 W/m²K. What is the brick inner surface temperature? (13 marks)
T #-T2 = 100°C E = 0.8 grad Tsur = 25°C Combustion gases 4 Cond conv k= 1.2 W/ mK 111 T = 25°C h = 20 W/m2K -L = 0.15m Air X Figure la