Superheated vapor is flowing at a rate of 1.08 106 grams/h inside a pipe in a power plant. The pipe is 1000 cm long, has an inner diameter of 0.05 m and pipe wall thickness of 0.6 cm.
The pipe has a thermal conductivity of 0.017 kW/m.K, and the inner pipe surface is at a uniform temperature of 393 K. The temperature drop between the inlet and exit of the pipe is 7 K, and the constant pressure specific heat of vapor is 2190 J/kg.K. If the air temperature in the power plant is 298 K,
(a) determine the outer pipe surface temperature and
(b) the heat transfer coefficient as a result of convection between the outer pipe surface and the surrounding air.