Cooler CO-201 Menentukan jenis Cooler
Reynold number, Re
a
Pada t
av
= 86
o
F
= 0,7076 lbjam ft Re
a
=
a e
G x
D
= 0,7076
623 1.121.542,
0,1312 x
= 207.951,3739
jH = 400 Gambar.24, Kern Pada t
av
= 86
o
F k = 0,3538 Btujam ft.
o
F cp = 1,0541 Btulb
o
F
3 1
k c
=
3 1
0,3538 7076
, 1,0541
= 1,282
hoΦ
a
=
3 1
k c
D k
jH
= 400 x
0,1312
0,3538 x 1,282
= 1.382,84 Btujam ft
2 o
F Reynold Number, Re
p
Pada T
av
= 189,5
o
F = 0,2661 lbjam.ft
Re
p
=
Gp
Dp
=
0,2661 15
287.622,02 0,1723 x
= 186.235,5291 jH = 380 Gambar.24, Kern
Pada T
av
= 189,5
o
F k = 0,0838 Btujam ft.
o
F cp = 2,4915 Btulb
o
F
3 1
k c
=
3 1
0,0838 0,2661
2,4915
= 1,7120
hiΦ
p
=
3 1
k c
D k
jH
= 380 x
0,1723
0,0838 x 1,7120
=316,407 Btujam ft
2 o
F
hioΦ
p
= hiΦ
p
x
OD
ID = 274,7955 Btujam ft
2 o
F Temperatur dinding T
w
T
w
=
c c
a p
a c
t T
x ho
hio ho
t
=
86 5
, 189
1.382,84 274,7955
1.382,84 5
, 189
x
Pada t
w
= 293,8342
o
F
w
= 0,3084 lbjam ft. Φ
a
=
w 0,14
= 0,70760,3084
0,14
= 1,1233 Koreksi koefisien ho
ho = hoΦ
a
. Φ
a
= 1.382,84 x 1,1233 = 1.553,3442 Btujam ft
2 o
F = 293,8342
o
F Pada T
w
= 293,8342
o
F
w
= 0,2931 lbjam ft. Φ
p
=
w 0,14
= 0,26610,2931
0,14
= 0,9866 Koreksi koefisien hio
hio = hioΦ
p
. Φ
p
= 274,7955 x 0,9866 = 271,1132 Btujam ft
2 o
F
Sehingga didapat Clean over all coefficient, Uc
o io
o io
h h
h h
Uc
.
1.553,3442 271,1132
1.553,3442 271,1132
x Uc
= 230,826 Btujam ft
2
.
o
F
Menghitung Ud Design Overall Coefficient
Rd = 0,001 hr.ft
2
.
o
Fbtu Tabel 8. Kern, 1965
Ud 1
= Rd
Uc 1
Ud 1
= 001
, 230,826
1
Ud 1
= 0,0053 Ud = 188,6792 Btuhr.ft
2
.
o
F
Menghitung A surface area required
A =
t .
U Q
D
=
80,5263 188,6792
2 617.743,24
= 40,658 ft
2
Menghitung jumlah hairpin
External surface lin ft, a = 0,917 ft
2
Tabel.11 Kern, 1965 Required length
, L = a
A
=
9170 ,
40,658
= 44,338 ft Panjang hairpin
= 12, 15, 20 ft Kern, 1965
Diambil L
h
= 20 ft
1 hairpin terdiri dari 2 pipa n = 2, maka jumlah hairpin yang diperlukan :
Hairpin =
h
2.L L
=
20 2
44,338
= 1,1085 2
Maka jumlah hairpins yang digunakan = 2 buah Koreksi panjang pipa :
L
kor
= 2.L
h
x hairpin = 2 x 20 x 2
= 80 ft linier