Three flat surfaces form a very long triangular duct. Two of the sides of the triangle are 10 cm in length, and are at right angles. The third surface is 14.14 cm in length. The two surfaces at right angles are at temperatures of 1000 K and 500 K respectively, and both have emissivities of 0.5. (a) Calculate the rate of radiant heat transfer from surface 1 (at 1000 K) and surface 2 (at 500 K), for a 1 metre length of duct. (b) Calculate the temperature of surface 3 (the re-radiating surface).

The third surface ( 14.14cm long) is a re-radiating surfac