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Q7. A deck steam line is 120 m long and carries 720 kg/hour of saturated steam.

The steam enters the line in a dry saturated state at a pressure of 20 bar.

The pipe has a outer diameter of 140 mm and is covered in two layers of insulation each 50 mm thick.

A change in the vessels operating conditions requires an additional layer of insulation to be added to the pipeline. The additional layer limits the steam condensation to 31.42 kg/hour and maintains the outer surface temperature of the pipe at 9℃.

Calculate EACH of the following:

(a) The dryness fraction of the steam leaving the pipe;(2)

(b) The heat loss from the pipe per meter length;(3)

(c) The thickness of the additional layer of insulation;(6)

(d) The interface temperature between the second and outer layers of insulation. (5)

Note: thermal conductivity of inner layer of insulation = 0.075 W/mK

Thermal conductivity of second layer of insulation = 0.4 W/mK

Thermal conductivity of additional outer layer of insulation = 0.04 W/mK