This presentation discusses filmwise and dropwise condensation. Condensation occurs when vapor is cooled below its saturation temperature, causing it to change into liquid when contacting a cooler surface. Dropwise condensation forms discrete droplets on the surface, which grow and slide off. It occurs on highly polished or contaminated surfaces treated with promoters. Filmwise condensation forms a continuous liquid film on the surface as more vapor condenses. The main differences are that dropwise condensation has 10 times higher heat transfer than filmwise, and occurs on non-wetting surfaces while filmwise occurs on wetting surfaces.

1. PRESENTATION ON FILMWISE AND
DROPWISE CONDENSATION
BY:
KRISHNA KHANDELWAL(10BEM0083)

3. WHAT IS CONDENSATION?
 Occurs when the temperature of vapour is
reduced below its saturation
temperature(Tsat).
 Saturation temperature is the temperature
at which vapour change into liquid.
 This is done by bringing the vapour into
contact with solid surface whose
temperature(Ts)is below the saturation
temperature of the vapour.

4. TYPES OF CONDENSATION
 DROPWISE CONDENSATION .
 FILMWISE CONDENSATION.

5. DROPWISE CONDENSATION
 The condensed vapor forms droplet on the
surface instead of continuous film.
 The small droplets that forms at the
nucleation sites on the surface grow as a
result of continued condesation,coalesce
into large droplets and slide down when
the reach the certain size.
 The surface is covered by countless
droplets of varying diameter.

7.  Observed to occur either on highly polished
surfaces. Or on surfaces contaminated with
impurities like organic compounds.
 It is achieved by adding a promoting chemical
into the vapour ,treating the surface with a
promoter chemical or coating the surface with
a polymer(teflon) or a noble metal(Ag,Pt,Au).
 The promoters used are wax ,fatty acid like
oleic ,linoic acid.
 Dropwise condensation didn’t last long and
converted to film condensation after
sometime

8. FILMWISE CONDENSATION
 The condensate tends to wet the surface
and thereby forms a liquid film.
 The liquid flows down the cooling surface
under the action of gravity.
 The thickness of the film increases in the
flow direction as more vapor condenses
on the film.

10. DIFFERENCE BETWEEN FILMWISE AND
DROPWISE CONDENSATION
 Heat transfer at in dropwise is 10 times
larger than in filmwise .
 In dropwise a large area of solid surface is
directly exposed to vapour .
 Dropwise condensation occurs on
nonwettable surface while filmwise occurs
on wettable surfaces.

11. THANK YOU