Question

system, hot water at an average temperature of 80°C is flowing through a 15-m section of a cast In a heating iron pipe (k 50 W/m K) whose inner and outer diameters are 4 cm and 5 cm, respectively. The outer surface of the pipe, whose emissivity is 0.75, is exposed to the cold air at 10°C in the basement. with a heat transfer coefficient of 15 W/m2.K. The heat transfer coefficient at the inner surface of the pipe is 120 W/m2 K. Taking the walls of the basement to be at 10°C also, determine the followings: a) rate of heat loss from the hot water, and b) the average mass flow rate of water in the pipe if the temperature of the water drops by 4°C as it passes 3. through the basement. c) Suppose, the water pipes are now used to supply hot water. If some insulation (k-0.05 W/m K) is provided, what should be the critical thickness of insulation around the pipe?

Answer 1