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