mass transfer part 4
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Transcript of mass transfer part 4
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7/24/2019 mass transfer part 4
1/6
INTPH-MS 1
DEFINISI:
KOEFISIEN PINDAH MASSA BINER
PADA SATU FASA
Contoh Pengeringan suatu lempeng
Dinding porous
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INTPH-MS 2
Transfer massa A dan B
dari cairan yang meleler
turun di dinding ke gas
yang bergerak ke atas
Pada y=0 (di permukaan) NA,0NB,0
pada fasa yang ditinjau
dalam hal ini fasa gas
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INTPH-MS 3
, 0 , 0| |y y B y y loc AJ J k x
= == =
arah y: ( ),0 ,0 ,0 ,0A A B AN x N N J + =
( )
( )
,0 ,0 ,0
,0 ,0 ,0
A A A B loc A
B B A B loc B
N x N N k x
N x N N k x
+ =
+ =
! 1- xA,0= xB,0cukup 1 persamaan
loc
k
sama di kedua perssimbol k dipengaruhi
laju perp massa
NA,0dan NB,0 kecil
( ),0
,0
,0 ,0 ,0
,00
limA
B
A A A B
x locN
AN
N x N Nk
x
+ =
-distorsi kecepatan profil konsentrasi } diabaikan
[ ], Re, ,x locAB
k Df Sc geometri
cD=
banyak kasus
untuk forced conv
, ,0 ,0
,
Re, , ,x loc A B
AB x loc
k D N Nf Sc geometricD k
+
=
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INTPH-MS 4
laju molar (untuk area A)
[ ],0 ,A A B x loc Aw x w w k A x + =
laju yang rendah
[ ],0 ,A A B x loc Aw x w w k A x + = ,A Bw w laju molar [flux x A]
identik dg perpindahan panas
[ ],0A A A Bw x w Qw +
A
x
x T
hk
contoh :
( ) ( ) ( ),0 ,1 ,0 ,1A A A B x A bw x w w k DL x x + =
didefinisikan atas
dasar xApada bidang 1
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INTPH-MS 5
perp panas2
0 0
L
r R
TQ k Rd dz
r
=
= +
perp massa
( )2
,0
0 0
L
AA A A B AB
r R
xw x w w cD Rd dz
r
=
+ = +
( )
2
1
0 1 0 0
1 L
r R
Th k Rd dz
DL T T r
=
= +
( )
2
,1
,0 ,1 0 0
1 L
Ax AB
A A r R
xk cD Rd dz rDL x x
=
= +
Dimensionless
,0 0
,1 ,0 1 0
/
/
A AA
A A
r r D
z z D
x x T Tx Tx x T T
=
=
= =
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INTPH-MS 6
perp panas:/ 2
1
10 0
2
1,1
2 /
L D
r
h D TNu d dz
k L D r
=
= =
perp massa:/ 2
,1
,110 02
1
2 /
L D
x AAB
AB r
k D xNu d dz
cD L D r
=
= =
Nu : bil Nusselt untuk perp panas tanpa perp massa
NuAB: bil Nusselt untuk perp massa yang pelan
Nu,1 = f (Re, Pr, L/D) untuk forced conv
NuAB= f (Re, Sc, L/D)
Sama untuk Nu,a
Nu,ln
Nu,loc
untuk free convection
Nu,m = f (Gr, Pr)
Nu,AB,m= f (GrAB, Sc)