Kỹ Thuật phân tán pha: Bài tập chương 3 – Trần Minh Mẫn MSSV:1511952 1.i A powder is contained in a vessel to form a cylindrical plug 0,8cm in diameter and 3cm long.. The powder density
Trang 1Kỹ Thuật phân tán pha: Bài tập chương 3 – Trần Minh Mẫn (MSSV:1511952)
1.(i)
A powder is contained in a vessel to form a
cylindrical plug 0,8cm in diameter and 3cm
long The powder density is 2,5gcm-3 and 2,2g
of powder was used to form the plug The
porosity inside the plug The porosity inside the
plug of powder is (-):
a.0,58 b.0,42 c.0,75 d 0,25
Solution 1(i):
The volume of the cylindrical plug:
2
2
3 3,14 0,8
o
cm D
The total volume of the powders:
3 3
2, 2
0,88 2,5
s s s
gcm
The total volume of the emties:
o s
The porosity inside the plug of powder:
3 3
0, 6272
0, 42
1, 5072
o
1.(ii)
Air was drawn through the plug at a rate
of 6.6 cm3 per minute A mercury
manometer was used to measure the
pressure drop during this process: a
pressure drop of 60 mm Hg was
recorded The specific gravity of mercury
is 13.6, thus the pressure drop across the
plug was (Pa):
a.80 b.800 c.8000 d.80000
Solution 1(ii):
The pressure drop:
1.(iii)
The superficial gas velocity in (ii) was (ms-1):
a.0,0022 b.3,65.10-5 c.2,2.10-6 d.0,00365
Solution 1(iii):
6 3
-1
10
6, 6
60 s
0, 0022 ms 3,14 0,8.10
o
m Q
U
1.(iv)
The viscocity of the air was 1,8.10-5 Pas, using
the Kozeny-Carman equation, the specific
surface area per unit volume of the powder was
(m-1):
a.2310 b.3,0.1011 c 5,5.10 5 d.1,2.106
Solution 1(iv):
3 2
3 2
5 1
1
5, 5.10
v
o
P S
L KU
Pa
m
1.(v)
The Sauter mean diameter of the powder was (
m):
a.2600 b.22 c.11 d.5
Solution 1(v):
5 1
11 5,5.10
v
S v
1.(vi)
The air density was 1,2kgm-3, the Modified
Reynolds Number of the system was (-):
a.0,1 b.8,4.10-10 c.4,6.10 -4 d.0,00021
Solution 1(vi):
1
4
Re
1, 2 0, 0022
4, 6.10
1 0, 42 5,5.10 1,8.10
dU
1.(vii)
Comment on whether your use of the
Kozeny-Carman equation was valid or not:
Solution 1(vii):
Trang 22.(i)
A cylindrical ion exchange bed composed
of spherical particles 2mm in diameter
packed at abed voidage of 0,45 is to be
used to deionise aliquid of density and
viscosity 1100kgm-3 and 0,0075Pas
respectively The design flow rate is 5m3h-1
and the bed height and diameter are 2 and
0,2m respectively, using the
Kozeny-Carman equation the pressure drop is (Pa):
a.99000 b.1,32.107 c.4400 d.44000
Solution 2(i):
Kozeny-Carman equation:
2 2 1
3
1
o v
K U S P
L
Tính:
3
1
5 3600
0, 0442 3,14 0, 2
o
m s Q
1 3
3000 2.10
v
0, 45 99000
P Pa
2.(ii)
The Modified Reynolds Number is:
a.3,91 b.4,78 c.1290 d.0,478
Solution 2(ii):
1100 0, 0442
1 0, 0075 1 0, 45 3000
o v
U
2.(iii)
Comment on your use of the
Kozeny-Carman equation:
Solution 2(iii):
2.(iv)
The interstitial liquid velocity inside the
bed is (ms-1):
a.0,02 b.0,098 c.0.08 d.0,044
Solution 2(iv):
1
1
0, 0442
0, 098
0, 45
o
2.(v)
Using the Carman correlation the shear
stress on the ion exchange beads is (Pa):
a.17,2 b.3,5 c.13,5 d.27
Solution 2(v):
1 1
17, 2
Pa
2.(vi)
Hence the dynamic pressure drop over the
bed is (kPa):
a.84 b.130 c.99 d.150
Solution 2(vi):
2
2
1
1 2
0, 45
1 0, 45 3000
v
S m
m
2.(vii)
Why is the answer to (vi) different to that
in (i)?
Solution 2(vii):
(i) Không kể ma sát (ii) Kể đến ma sát
???
2.(viii)
If the liquid has a datum height equal to the
position at the base of the ion exchange
vessel and, therefore, needs raising to the
top of the column before it enters the ion
exchange bed the additional pressure drop
to effect this, i.e the static pressure drop
over the bed, is (kPa):
a.2,16 b.21,6 c.216 d.0,22
Solution 2(viii):
1100 9,81 2 21600 21, 6
static