Page 174 - Design and Operation of Heat Exchangers and their Networks

162 Design and operation of heat exchangers and their networks

10 10 4
Annular
X =1.6 Bubble
1 f 10 3
f
F
T
T,F 10 −1 10 2 K
Wavy Intermittent
(plug/slug)
10 −2 10
f K
Stratified
10 −3 −3 −2 −1 2 3 4 1
10 10 10 1 10 10 10 10
X
Fig. 4.3 Generalized flow regime map for horizontal two-phase flow (Taitel and
Dukler, 1976).

4.1.2.5 Convective flow boiling in vertical tubes
For convective flow boiling in vertical tubes
(
2:2
0:35
α c,v 0:01 1:5 0:6
¼ ð 1 _xÞ ð 1 _xÞ +1:9_x ρ =ρ g
f
α lo
) 0:5
2
0:67
α go
+ _x 0:01 1+8 1 _xÞ 0:7 ρ =ρ (4.62)
ð
f g
α lo
in which α lo and α go are the local single-phase heat transfer coefficients based
on the mass velocity G for the liquid (liquid only) and the vapor (gas only),
respectively.
4.1.2.6 Convective flow boiling in horizontal tubes
For convective flow boiling in horizontal tubes

(
2:2
0:37
α c,h 0:01 0:4
¼ ð 1 _xÞ ð 1 _xÞ +1:2_x ρ =ρ g
l
α lo
) 0:5
2
0:67
α go
+ _x 0:01 1+8 1 _xÞ 0:7 ρ =ρ (4.63)
ð
l g
α lo