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DesignEx Heat Transfer Relations

Gas/Liquid Inside Tube

Basis:  Zukauska Method

desexeq1.gif (1214 bytes)
where:

a b c NRe
0.90 0.40 0.36 0-100
0.52 0.50 0.36 100-1000
0.27 0.63 0.36 1000-200000
0.033 0.80 0.40 200000-2000000


Gas/Liquid Outside Tubes

Basis: Delaware Method, 25% segmental baffle cut

ho = jo Cp (shellside mass flow/shell cross sectional area) NPr(-2/3)

desexeq2.gif (1543 bytes)

where:

desexeq3.gif (1229 bytes)

shell cross sectional area = [BDs(s-Do)] / s
                    where:
                               B = Baffle spacing
                               Ds = shell diameter
                               s = tube spacing
                               Do = outside tube diameter

 

For a 300 tube layout angle:

NReshell a1 a2 a3 a4
0-10 1.400 -0.667 1.450 0.519
10-100 1.360 -0.657 1.450 0.519
100-1000 0.593 -0.477 1.450 0.519
1000-10000 0.321 -0.388 1.450 0.519
10000-100000 0.321 -0.388 1.450 0.519

For a 900 tube layout angle:

NReshell a1 a2 a3 a4
0-10 0.970 -0.667 1.187 0.370
10-100 0.900 -0.631 1.187 0.370
100-1000 0.408 -0.460 1.187 0.370
1000-10000 0.107 -0.266 1.187 0.370
10000-100000 0.370 -0.395 1.187 0.370


Condensation Inside Tubes

Basis:  Kern's Method

desexeq4.gif (1960 bytes)

Condensation Outside Tubes

Basis: Iterative solution derived from Nusselt Equation

desexeq5.gif (2071 bytes)

where:

N = shell diameter / (ODtube + Tube spacing)
Tfilm = Tsat - 0.75 (Tsat - Twall)

Vaporization Inside/Outside Tubes

Basis: Rohsenow's Method for Nucleate Boiling

desexeq6.gif (1481 bytes)

where:

D = outside tube diameter for shellside
D = inside tube diameter for tubeside

 

Reference: Heat Exchanger Design Handbooks, Bagel House Publishing 1998

 

 


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