For the double-pipe heat exchanger of Problem 3.10,calculate the outlet temperatures of the
two streams when the unit is first placed in service.
Q:3.10
A hydrocarbon stream is to be cooled from 200â—¦F to 130â—¦F using10,800 lb/h of water with
a range of 75–125◦F. A double-pipe heat exchanger comprised of 25ft long carbon steel
hairpins will be used. The inner and outer pipes are 1.5- and3.5-in. schedule 40, respectively.
The hydrocarbon will flow through the inner pipe and theheat-transfer coefficient for this
stream has been determined: hi = 200 Btu/h · ft2
·
◦F. Fouling factors of 0.001 h · ft2
·
â—¦F/Btu
for water and 0.002 h · ft2
·
â—¦F/Btu for the hydrocarbon are specified. How many hairpinswill
be required?
