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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

-

-

-

-

-

1.6

1.6

1.6

1.6

-

-

2.0

2.0

2.0

2.0

2.0

2.0

-

2.6

2.6

2.6

2.6

2.6

-

-

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,