Chapter 20
20.1 Second order reaction: r kCA
2; k Ae E RT
If ideal Ci
PiRT if ideal
220ºC = 493K
E
R5957.35 K
(b) r2
r
k2
k1
CA2
2
CA1
2
2P2
P
2
1.121.21
20-2
20.2 P
Tank 3 atm P
1; P25 at
m
«
v
112.5 m3
h
Assume turbulent flow
20.3
ln RORi
k
ln 15.875 mm14.225 mm
45 Wm
0.002438
1
Ui1
UO2
1
2000 0.002438 15.875
14.225
1
700
Tube
Organic
Shell
Cooling Water
hi = 700 W/m2K
hO = 2000 W/m2K
20-4
20.4
(assumed unchanged)
1
UO1
1
UO2
UO2
UO1
1
hO1
0.00035 1
hi1
1
hO2
0.00035 1
hi2
(b) hi21000 0.8 0.8 836.5 W/m2K
1
UO2
1
500 W/m2K0.00035 m2K/W 1
836.5 W/m2K
hi = 1000 W/m2K
hO = 500 W/m2K
20-5
20.5
hO >> hi assumed since hO is condensing and hi is process gas
Gas
Tubes
20.6
P2P
1
P
1
2.96 1
11.96
rx
r
20-7
20.7
L
PR
v8
4
(a) Pv 3x
(e) 1.1503.53
4
1
2
1
2
1
2
4
D
D
P
P
v
v
PRv
20-8
20.8 (a)
(b)
(c)
160
254
187
20-9
20.9
Di = 7.981 in = 202.7 mm
A = 322.7 x 10-4 m2
At STP air
kmol
22.4 m3
29 kg
kmol 1.295 kg
m3
4.6 10 5 m for commercial steel
00023.0
m 2027.0
m 106.4 5
D
20-10
20.10 dNA
dt rAVNANAO 1x
NAO
dx
dt rAV
CAO
dx
dt rAV
(a) t2
t1
1
k2
ln 1
1x2
1
k1
ln 1
1x1
ln 1
1 0.95
ln 1
1 0.90
ln 20
ln 10 1.30
x20.91
20-11
20.11 rA
K1CA
1K2CA
K1CAO 1x
1K2CAO 1x
dx
K
K
xCK
dx
C
r
dx
Ct
x x
AO
AO
x
A
AO
0 0 1
2
1
0
1