Page 210 - Design and Operation of Heat Exchangers and their Networks

Optimal design of heat exchangers 199

Then the number of tubes in one window section can be obtained from

(5.22)
N tw ¼ F w N t
The fraction of the total number of tubes in the crossflow section can be
readily obtained from F w :
F c ¼ 1 2F w ¼ 1 θ ctl sinθ ctl Þ=π (5.23)
ð
which also yields the number of tubes in the crossflow section as
N tc ¼ F c N t (5.24)
The shell-side flow area in the window section is obtained from
1 π
2
A sw ¼ d θ ds sinθ ds Þ N tw d o 2 (5.25)
ð
s
8 4
The shell-side crossflow area of main stream (stream B) is given by

s d o
A sc ¼ l bc δ st + d ctl for 30and 90degrees layouts (5.26)
s
" #
s d o
A sc ¼ l bc δ st + d ctl p ffiffiffi for 45degrees layout (5.27)

2=2 s
The shell-to-baffle leakage area of stream E within the circle segment of
the baffle is determined by

θ ds
A sb ¼ 1 πd s δ sb =2 (5.28)
2π
The baffle hole-to-tube leakage area of stream A can be expressed as
π
π 2 2
ð
A bt ¼ ð d o + δ bt Þ d N t 1 F w Þ d o δ bt N t 1 F w Þ (5.29)
ð
o
4 2
The shell-to-tube bundle bypass area of streams C and F is evaluated by
∗

A bp ¼ l bc δ st + N tp δ tp (5.30)
∗
where δ tp expresses the effect of the bypass stream F through the pass divider
lane in tube bundle in the crossflow direction:
8
0 for standard calculation
<
∗
δ tp ¼ d o for estimation (5.31)
:
δ tp =2 for rating