An unshielded thermocouple is used to measure the temperature of a stream of hot air. Assume the thermocouple surface is diffuse-gray, the emittance of the thermocouple is 0.8 and the area of the thermocouple is 0.1 mm2 . The convection heat transfer coefficient between the thermocouple and the hot air stream is 80 W/m2 K. The thermocouple radiates to the environment at 300 K, and there is no radiative exchange between the hot air stream and the thermocouple. If the reading of the thermocouple is 600 K, what is the temperature of the hot air stream (20 points)