This document discusses different types of condensation and heat exchangers. It describes two types of condensation - film condensation where condensate forms a liquid film on a surface, and dropwise condensation where condensate forms droplets. It also discusses log mean temperature difference, a metric used to calculate heat transfer in a heat exchanger where the temperature difference varies along its length. Counter flow arrangements are noted to be more effective for heat exchange. Industrial temperature control of heat exchangers is also briefly covered.

1. 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

2. 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

3. Film Condensation

4. 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

5. Drop-wise Condensation

6. 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

7. 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)

8. ∆T IS NOT CONSTANT

9. 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

10. Equations for log mean temp diff

11. Industrial Temp Control of
Heat Exchangers
Temp control of exchanger
Set
Point TC
TT
Steam in
Process fluid

12. TCV-4 TCV-3
TIC TIC
TT
Condensate -2 -1
SC FIC TT
FT
-1 -1
PCV-1
MCV-1 HIC-1
Heat Condensate
SC
Recycle
V-1
-2 Heat Recycle
E-1A From E-5A PC
-1
From F-3AB E-2A
From C-1A
SC FIC HIC-2 PT
FT
-3 -3
TCV-6 TCV-5
TIC
-4
TIC
-3
TT NODE 2
Condensate
TT
P-3ABC
PCV-2
MCV-2 HIC-3
Heat Condensate
Recycle V-2
Heat Recycle
E-1B From E-5B PC
-2
E-2B From C-1B
HIC-4
PT

13. C-1A
1ST stage 2nd stage 3rd stage 4th stage PIC
5th stage -69
PCV-69
TWR MCV-5 To V-1
CWS CWR TWS To
CO2 from Ammonia plant PIC
CWS CWR
CWS CWR From TK-12
-20 TCV-27
PCV-20
NODE 4
C-1B
1ST stage 2nd stage 3rd stage 4th stage PIC
5th stage -70
PCV-70
TWR MCV-6 To V-2
TWS
CWS CWR To
PIC CWS CWR From
CO2 from Ammonia plant
TCV-28 TK-12
CWS CWR
-29
PCV-29
TCV-28
Temper water system
TCV-27
To C-1A
TCV-26
To C-1AB jackets C-1B
To
TK-12
P-30AB
CWS CWR
E-30AB

14. Heat Recycle
E-3 Condensate
E-5A
Heat
Recycle
Heat Recycle Condensate
E-4A
To V-1
MCV-3
Condensate
P-4AB
E-5B
Heat
Heat Recycle Recycle
NODE 3
P-5ABC
Condensate
E-4B
To V-2
MCV-4

15. Thank You
for
Your Attention