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Q7. A steam pipe 150 m in length has an internal diameter 150 mm and wall thickness of 15 mm is covered in a layer of insulation 50 mm thick.

Dry saturated steam enters the pipe at a pressure of 20 bar with a flow rate of 750 kg/hour.

The ambient temperature is -10°C

Calculate EACH of the following:

(a) the overall heat transfer coefficient of the pipe;(4)

(b) the heat lost from tie pipe per hour; (2)

(c) the mass of steam condensed per hour; (6)

(d) the percentage change the steam velocity between inlet and exit. (4)

Note: inner surface heat transfer coefficient

thermal conductivity of steel = 55 W/mK

thermal conductivity of the insulation = 0.05 W/mK

outer surface heat transfer coefficient = 14W/m²K