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Q8. Wet steam at a pressure of 12.0 bar flows in a 10 m long pipe of inside diameter 30 mm and wall thickness 4 mm. The pipe is surrounded with a layer of lagging 20 mm thick. The thermal conductivity of the lagging is 0.04 W/m K and the outside surface heat transfer coefficient is 15 W/m² K. The outside air temperature is 32°C. The thermal resistances of steam film and pipe wall may be disregarded. Determine EACH of the following:

(a) The rate of heat loss

(b) The outside surface temperature of the lagging

(c) The increase in the rate of heat loss which would result if the thickness of the lagging were reduced to 15 mm.