Page 115 - Process Equipment and Plant Design Principles and Practices by Subhabrata Ray Gargi Das

112 Chapter 4 Shell and tube heat exchanger

Table P4.1 Fluid specifications in design illustration.
Kerosene inlet, /
T h;in ¼ 130 C T h;avg ¼ 90 C

55 710 (Following properties are at 90 C)

¼ 10:8472 kg s
3600 C pk ¼ C ph ¼ 2:343 10 J kg K
m h ¼
3

Kerosene exit,
m k ¼ 0:00027 Pa s
T h;out ¼ 50 C

3
r k ¼ 710 kg m
k k ¼ 0:148225 W=mK
Pr k ¼ C pk =ðm c k c Þ¼ 4:2715
CW exit, T c;out ¼ 45 C )

T c;avg ¼ 39 C

(Following properties are at 39 C)

3
r w ¼ 992:22 kg m
m w ¼ 0:000642 Pa s CW inlet, T c;in ¼ 33 C

3

C p;w ¼ C pc ¼ 4:18 10 J kg K
k w ¼ 0:62976 W=mK

Pr w ¼ C p;w m w k w ¼ 4:26
D 1 ¼ 130 45 ¼ 85 C 85 17 D 2 ¼ 50 33 ¼ 17 C

¼ 42:25 C

85
DT LMTD ¼
ln
17
For the design condition,
T h;in T h;out 130 50
¼ 6:6667
R ¼ ¼
T c;out T c;in 45 33
and
T c;out T c;in 45 33
¼ 0:12371
S ¼ ¼
T h;in T c;in 130 33
Assuming single shell pass, we calculate F T from Eq. (4.3).
From Eq. (4.4),
q ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi
p ffiffiffiffiffiffiffiffiffiffiffiffiffiffi 1 0:12371
2
2 ð6:6667Þ þ 1 ln ¼ 10:849
X ¼ R þ 1 lnfð1 SÞ=ð1 RSÞg ¼
1 ð6:6667 0:12371Þ
and from Eq. (4.5),

8 9
p ffiffiffiffiffiffiffiffiffiffiffiffiffiffi
2
R þ 1 =
<2 S R þ 1
Y ¼ðR 1Þ ln

p ffiffiffiffiffiffiffiffiffiffiffiffiffiffi
R þ 1
: 2 ;
2 S R þ 1 þ

2
p ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi
6:6667 þ 1
2 0:12371 6:6667 þ 1
¼ 5:6667 ln ¼ 12:236
p ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi
2
6:6667 þ 1
2 0:12371 6:6667 þ 1 þ