A steel pipe (k = 48 Wmí1 Kí1 ) of a heating system carries wet steam at 120°C. The inner and outer diameters of the pipe are 15 cm and 16 cm respectively. The pipe is insulated on the outside with...

A steel pipe (k = 48 Wmí1 Kí1 ) of a heating system carries wet steam at 120°C. The inner and outer diameters of the pipe are 15 cm and 16 cm respectively. The pipe is insulated on the outside with rockwool insulation (k = 0.05 Wmí1 Kí1 ) of thickness 8 cm. The ambient air temperature is 32°C. The outside heat transfer coefficient is 20 Wmí2 Kí1 . The thermal resistance between the inner pipe surface and the steam is negligible. Calculate (i) the rate of heat flow from the steam to the ambient over a 5 m length of pipe, (ii) the temperature of the insulation surface and (iii) the rate of condensation of steam over the 5 m length of pipe if the latent heat of steam is 2200 kJkgí1 .