Page 139 - Design and Operation of Heat Exchangers and their Networks

Steady-state characteristics of heat exchangers 127

the correlations for louver fin and flat tube heat exchangers will also be intro-
duced in this section.
Based on the data from the literature for louver fin heat exchangers hav-
ing flat tube configuration, Chang et al. (2000) proposed a friction correla-
tion as follows:

f ¼ f 1 f 2 f 3 (3.295)
where
8
0:805s=h 3:04
< 14:39Re ln 1 + s f =l p , Re l p < 150
l p
f 1 ¼ 0:6049 1:064=θ 0:2 0:527
4:97Re ln 0:9+ δ f =s f Þ , 150 < Re l p < 5000
: s 0:5
ð
l p
(3.296)
8
h i
3:01 1:435
> 0:48
ð
< ln 0:9+ δ f =s f Þ < 150
d h =l p ln 0:5Re l p ,Re l p
f 2 ¼ h i
2:966
ð
> 0:7931s t = s t b t Þ
: ð s f =h l Þ , < 5000
d h =l p ln 0:3Re l p 150 < Re l p
(3.297)
8
0:308 0:1167s t =b t 0:35
ð
> ð ½ s f =h l Þ l s =h l ފ e θ s , Re l p < 150
<
3:553
f 3 ¼ 1:4
> 0:0446 θ 0:477 < 5000
: ð s t =b t Þ ln 1:2+ l p =s f s , 150 < Re l p
(3.298)
The correlation for the Colburn j factor was proposed by Chang and
<3000 as
Wang (1997) for 100<Re l p
0:27 0:14 0:29 0:23 0:68 0:28 0:05

j ¼ Re 0:49 θ s s f h f B t h l s t δ f
l p
90 l p l p l p l p l p l p
(3.299)
Based on the experimental data from 45 heat exchanger samples, Kim
and Bullard (2002) obtained the following correlations for s f <l p :
0:444 1:682 1:22 0:818 1:97
f ¼ Re 0:781 θ s s f h f l s h l (3.300)
90 l p l p l p l p
l p
! 0:13 ! 0:29 ! 0:235 ! 0:68 ! 0:279 ! 0:05
0:257
0:487 θ s s f h f l s h l s t δ f
j ¼ Re
l p 90 l p l p l p l p l p l p
(3.301)
Other correlations can be found in the literature (Achaichia and Cowell,
1988; Li and Wang, 2010; Ryu and Lee, 2015; Deng, 2017; Shinde and Lin
(2017)).