Question

Steam at its saturation temperature of 65°C is condensing on the outside
of a tube with outside diameter 2.5cm and length 3m. The tube is
maintained at 35°C by flow of cooling water through it. Calculate the
average heat transfer coefficient over the tube length and the rate of
condensate flow at the bottom of the tube. Physical properties can be
found in data tables.

Find the heat transfer coefficients for the vertical and horizontal tubes using both the Nusselt equation and the McAdams equation.

Answer 1

Steam

T1 = 65°C

Tf = 35°C

d = 2.5 cm

L = 3 m

From Perry handbook physical properties are calculated at average temperature = (65+35) /2 = 50°C

Kf = 0.6436 W/mK

= 0.0831 kg/m3

= 10×10-6 Pas

= 2346.304 KJ/kg

For horizontal tubes

h = 35.3466 W/m2K

For vertical condenser

h = 13.890 W/m2K

= 0.6436/(13.890) = 0.04633

Subsituting we get

= 0.22464

For vertical condenser

m = 0.22464(3) = 0.67392 kg/s

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