1. Water with an average temperature of 75°C and an mean velocity of 1.5 m/s
is flowing through a pipe that has an outer diameter of 5 cm. The pipe extends
2 m in the ambient air above the ground, dips into the ground (k=2.5 W/m·K)
vertically for 3 cm, and continues horizontally at this depth for 20 m more
before it enters the next building. The first section of the pipe is exposed to
the ambient air at 8°C. Neglect the pipe conduction resistance. If the surface
of the ground is at 10°C, determine (a) the total rate of heat loss from the hot
water and (b) the temperature drop of the hot water as it flows through this
25-m-long section of the pipe. (c) Calculate the heat rate if whole pipe is in
air horizontally with total length 22.03 m. (d) Calculate the heat rate if whole
pipe is buried in soil horizontally with total length 22.03 m. Assume necessary
conditions.
(10+3+3+4)