diyoeshy rizqi
TRANSCRIPT
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Nama : DIYOESHY RIZQI PATRIA
NIM : 03101403066
PERPINDAHAN PANAS
Soal 12.1.
Diket : T1 = 95 C
T2 = 40 C
t1 = 25 C
t2 = 40 C
Jawab :
Cp Methanol = 2.84 Kj/kg
Cp air = 4,2 Kj/kg
Cooling water flow
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Dari gambar 12.19
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Ft = 0,85
Dari gambar 12.1
U = 600 W/m2
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L = 4,83 m
Outside diameter (mm) Wall thickness (mm)
16
20
25
30
38
50
1.2
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1.6
1.6
1.6
1.6
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2.0
2.0
2.0
2.0
2.0
2.0
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2.6
2.6
2.6
2.6
2.6
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3.2
3.2
3.2
3.2
Area of one tube = 4,83 x 20 x 10-3
= 0,303 m2
Number of tube
Triangular pitch, pt = 1.25 do
No.
passes1 2 4 6 8
K1
n1
0.319
0.142
0.249
2.207
0.175
2.285
0.0743
2.499
0.0365
2.675
Square pitch, pt = 1.25 do
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No.
passes1 2 4 6 8
K1
n1
0.215
2.207
0.156
2.291
0.158
2.263
0.0402
2.617
0.0331
2.643
Bundle diameter Db 20
Dari gambar 12.10
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Bundle diametrical clearance = 68 mm
Shell diameter, Ds = 826 mm + 68 mm = 894 mm
Tube side coefisient
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Mean water temperature =
Tube cross-sectional area x i.d
Water mass velocity
hi =
( )
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Viskositas air = 0.8 mNs/m2
Konduktivitas Thermal = 0.59 W/ m2
= 14,925
= 302
Dari gambar 12.23 , jh = 3,7 x 10-3
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hi
Shell-side coefficient
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Q = U A Tm
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Soal 12.2.
Gunakan Bells Mehtod untuk menghitung koefisien transfer panas Shell Side dan pressure drop
untuk design exchanger pada contoh 12.1 .
Diketahui :
Nember of tube (Nt) 918 mm
Shell I.d (Ds) 894 mm
Bundle diameter (Db) 820 mm
Tube O.d (Do) 20 mm
Pitch 1,25 (Pt) 25 mm
Tube Length (L) 4830 mm
Baffle Pitch (lb) 356 mm
Fluid flow rate on the shell side (Ws) 100.000 kg/s
Methanol density () 750 kg/m3
Viscosity () 0,34 x 10-3
kg/m s
Heat Capacity (Cp) 2,84 kJ/kgo
C
Thermal Conductivity (kf) 0,19 W/moC
Penyelesaian :
Heat Transfer Coefficient
Ideal bank coefficient, h
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Dari Grafik 12.31 diatas, didapatjh= 5,3 x 10-3
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Prandtl Number didapatkan dari Soal 12.1:
Viscocity correction factor (/w) diabaikan.
Tube Row Correction Factor, Fn.
Tube vertical pitch,
Baffle cut height, Bc = 25% = 0,25
Height between baffle tips,
Dari Grafik 12.32, Fn = 1,03.
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Window correction factor, FW
L
Bundle cut
Dari Grafik 12.41 at cut of 0,23
Tube in one window area,
Tube in cross-flow area,
Dari Grafik 12.33 didapat nilai
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Bypass correction,
=1,35 untuk Aliran Transisi dan Turbulen, Re >100
[ ]
Leakage correction, FL
Gunakan clearances spesifik standard
(Cs) Tube to baffle
(Cb) Baffle to shell
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Dari grafik 12.41, 25% cut (0,25), b = 2,1 rads.
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Dari grafik 12.35, didapat nilai L = 0,31
Shell-Side Coefficient
Hs didapat lebih kecil daripada Metode Kern.
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Pressure Drop
Cross-flow zone
Dari Grafik 12.36, Re = 25.691 untuk 1,25 pitch,jf= 5,6 x 10-2
.
Viscocity term (/w), diabaikan.
( x = 4,0 )
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Dari grafik 12.38, L = 0,52.
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Window zone
Dari grafik 12.41 untuk Baffle Cut 25% (0,25), Ra = 0,19.
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End zone
Total Pressure Drop
Number of baffle,