Memilih Fan


Hukum Fan

Volume Flow à Q2 = Q1 x (n2/n1) x ( d2/d1) 3

Pressure  à p2 = p1 x (n2/n1)2 x ( d2/d1)2 x ( r2/r1)

Absorbed Power  à Pw2 = Pw1 x  (n2/n1)3 x ( d2/d1)5 x ( r2/r1)

Density  à r2 = r1 x ( B2/B1) x (T1/T2)

Sound Power à Lw2 = Lw1 + 55 log 10 (n2/n1) + 55 log 10 ( d2/d1) + 55 log 10 ( r2/r1)

Efficiency à h % = Q x Pt /( 10 Pw )

Total Pressure à Pt = Ps + Pd

Dynamic Pressure à Pd = 0.6 V2

Keterangan Symbol :

Q = Volume Aliran Udara (m3 /s)

N = Kecepatan  Fan ( rpm )

d = Diameter Empeller (m)

p = Tekanan Fan ( Pa )

r = Kerapatan Udara ( kg/m3 )

Pw = Power yang dibutuhkan ( kw )

Lw = Sound Power Level (dB )

B = Barometric Pressure ( Pa)

T = Temperatur Absolute K =( oC + 273 )

Pt = Total Pressure (Pa)

Ps = Tekanan Statik Fan ( Pa)

Pa = Tekanan Dinamik Fan ( Pa)

V = Kecepatan Udara ( m/s )

Konversi factor :

Aliran :

1 CFM = 1,699 m3 /h = 0.472 l/s

1 m3 /h = 0,589 CFM = 0,278 l/s

1 l/s = 2,119 CFM = 3,6 m3 /h

Kecepatan :

1 ft/min = 0,0051 m/s

1 m/s = 196 ft/min

Volume :

1 ft3 = 0,00283 m3

1 m3 = 35,31 ft3

Tekanan :

1 inWG = 249,1 Pa = 25,4 mmWG

1Pa = 0,004 inWG = 9,8 mmWG

1 mmWG = 0,0393 inWG = 0,102 Pa

Misal :

Dibutuhkan aliran udara = 10000 m3 /h

Pressure = 80 mmWG

Tentukan

Ukuran Fan, Speed, Pd, Ps, kecepatan aliran, effisiensi , Pw

Jawab

Ukuran Fan = 500 mm

Speed fan = 850 rpm

Pd = 12 mmWG

Ps = Pt – Pd = 80 – 12 = 68 mmWG

V = 13,8  m /h

Eff = 66%

Pw = 3,5 Kw

Pm = Pw x 1,2 = 3,5 Kw x 1,2 = 4,2 Kw ( motor < 10 kw  = 20 % , motor > 10 kw = 15 %)

Tentang suwandikcf

Electrical Enginner
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