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120 Applied Process Design for Chemical and Petrochemical Plants

26
The charts of Chen are also useful for solving the equa-
tions for condensing coefficients; however, the correction
for the effect of multiple fluid stream is not included. There-
fore, the results should be conservative.
34
Devore has presented useful charts for solving a multi-
tube condenser design as shown in Figures 10-68, 10-69, and
10-70. Figure 10-71 is useful for condensing steam. The
charts all follow Nusselt’s basic presentation; however, a cor-
rection for turbulence of the film and other deviations is
included.
Rohsenow and Hartnett 166 present Nusselt’s relation for
the heat transfer average for horizontal tubes in a bundle
condensing vertically from tube to tube, top to bottom tube:

3
3g l 1 l v 2k h¿ fg 4 1>4
h 0.728 ,
3nD o T4
average for horizontal tubes in vertical bank (10-80)
Figure 10-69. Turbulence correction factor for horizontal multitube
where banks. Evaluate N a by solving for n s from Figure 10-68. (Used by per-
2
g acceleration of gravity, 32.17 ft/hr [ft/sec 2 mission: Devore, A. Petroleum Refiner, V. 38, No. 6, ©1959. Gulf Pub-
2
(3,600) ] lishing Company, Houston, Texas. All rights reserved.)
D o tube outside diameter, ft
c specific heat of liquid at constant pressure
2
h heat transfer coefficient, Btu/(hr) (ft )(°F)
3
h fg h fg ( / 8 ) c(T s T w )

Figure 10-68. Number of condensate streams in a horizontal bundle. Figure 10-70. Condensate film coefficients—vertical or horizontal.
(Used by permission: Devore, A. Petroleum Refiner, V. 38, No. 6, (Used by permission: Devore, A. Petroleum Refiner, V. 38, No. 6,
©1959. Gulf Publishing Company, Houston, Texas. All rights ©1959. Gulf Publishing Company, Houston, Texas. All rights
reserved.) reserved.)