Question A feedwater heater that supplies a boiler consists of a shell-and-tube heat exchanger with one shell pass and two tube passes. One hundred thin-walled tubes each have a diameter of 20 mm and a length (per pass) of 2 m. Under normal operating conditions water enters the tubes at 10 kg/s and 290 K and is heated by condensing saturated steam at 1 atm on the outer surface of the tubes. a) Draw the temperature profile, with labels, for the steam and water passing through the heat exchanger. Given that the convection coefficient of the saturated steam is ho 10,000 W/ m2 .K. Assume negligible
Question
A feedwater heater that supplies a boiler consists of a shell-and-tube heat exchanger with one shell pass
and two tube passes. One hundred thin-walled tubes each have a diameter of 20 mm and a length (per
pass) of 2 m. Under normal operating conditions water enters the tubes at 10 kg/s and 290 K and is heated
by condensing saturated steam at 1 atm on the outer surface of the tubes.
a) Draw the temperature profile, with labels, for the steam and water passing through the heat exchanger.
Given that the convection coefficient of the saturated steam is ho 10,000 W/ m2
.K. Assume negligible
internal and external fouling, negligible heat loss to the surroundings, constant properties, and fully
developed water flow in tubes, determine the following:
b) The overall heat transfer coefficient, Uo , for the heat exchanger.
c) The maximum heat transfer rate of the heat exchanger.
d) The outlet temperature of the cooling water (Tco).
e) The condensation rate of the steam ṁh
f) Using Excel, compute and plot Tco and ṁh as a function of the water flow rate 2≤ ṁc ≤ 20 kg/s with all
other conditions remaining the same, but accounting for changes in U.
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