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Condensation Heat Transfer Condensation occurs when
temperature of a vapor is reduced below its saturation temperature.
Vapor is contacted by a solid surface at a temp well below vapor saturation temp
Condensation Types A) Film Condensation B) Drop-wise Condensation
Film Condensation
Condensate wet the surface and form a liquid film on the surface which fall due to gravity
Thickness of film increases as it moves down due to more condensation
Film Condensation
Drop-wise Condensation
Condensed vapors form droplets on surface instead of film, surface is covered by drops
Droplets slide down the surface, when they reach a certain size
Drop-wise Condensation
Heat Exchanger
LMTD Definition Log mean temp difference is
defined as that temperature difference which, if constant, would give the same rate of heat transfer as actually occurs under variable conditions of temperature difference
Why Log Mean Temp Difference is used
Derivation of this equation is
based on constant ∆T, But temperature difference between hot and cold fluid varies through out the length of exchanger (so its not constant). ∆T is larger at inlet of heat exchanger, but decreases as fluid moves towards outlet. To have constant ∆T, we use ∆Tlm (log mean temp difference)
∆T IS NOT CONSTANT
Counter Flow arrangement is more better
When cold fluid out, its in contact with hot fluid at higher temp, so t2 can be higher than T2
Equations for log mean temp diff
Industrial Temp Control of Heat Exchangers
Temp control of exchanger
TCTT
Set Point
Process fluid
Steam in
FTFIC-1
PC-1
SC-1
PT
SC-2
FTFIC-3
SC-3
TTTIC-1
TIC-2
PC-2
PT
TTTIC-3
TIC-4
TT
TT
From F-3AB
P-3ABC
E-1A
E-2A
V-1
E-1B
E-2B
V-2
TCV-3TCV-4
TCV-5TCV-6
MCV-1
MCV-2
HIC-1
HIC-2
HIC-3
HIC-4
PCV-1
PCV-2
From E-5A
From C-1A
From E-5B
From C-1B
Heat RecycleHeat
Recycle
Heat RecycleHeat Recycle
Condensate
Condensate
Condensate
Condensate
NODE 2
C-1A
CO2 from Ammonia plant CWS CWRCWS CWR CWS CWR TWS
From TCV-27
TWRTo
TK-12
PCV-69
MCV-5
PCV-20
PIC-20
PIC-69
1ST stage 2nd stage 3rd stage 4th stage 5th stage
To V-1
CWS CWRCWS CWR CWS CWR TWS
From TCV-28
TWRTo
TK-12
MCV-6
PCV-29
PIC-29
PIC-70
1ST stage 2nd stage 3rd stage 4th stage 5th stage
CO2 from Ammonia plant
C-1B
To V-2
PCV-70
Temper water system
TK-12
P-30AB
E-30AB
CWS CWR
TCV-28
TCV-27
TCV-26
To C-1B
To C-1A
To C-1AB jackets
NODE 4
Heat Recycle
E-3
P-5ABC
P-4AB
E-4A
E-4B
E-5A
E-5B
To V-1
To V-2
MCV-3
MCV-4
Heat Recycle
Heat Recycle
Heat Recycle
Heat Recycle
Condensate
Condensate
Condensate
Condensate
NODE 3
Thank Youfor Your
Attention