A pipe carrying steam runs in a large room and is exposed to air at a temperature of 30C. The pipe surface temperature is 200C. The pipe diameter is 20 cm. If total heat loss rate from the pipe per metre length is 191.93 W/m, determine the

pipe surface emissivity. Use correlation Nu = 0.53 (Gr Pr)1/4

and properties of air at 115C: k = 0.03306 W/m?K, v = 24.93 106 m?/s, Pr=

0.687.