The Two types of Overhead condenser are used for distillation tower

1. Horizontal condenser (dropwise condensation

2. Vertical condenser (Film wise condenser)

In dropwise condensation the condensate liquid collects in the form of countless droplets of varying diameters on the condensing surface, instead of forming a continuous film, and does not wet the solid cooling surface. The droplets develop at points of surface imperfections (pit, scratch), called nucleation sites, and grow in size as more vapors condenses on its exposed surface. When the size of droplets is large there comes a time the droplet breakaway from the surface and knock off other droplets and carries it downstream. The moving droplet devours the droplets of smaller size. Dropwise condensation is one of the most effective mechanism of heat transfer and extremely large heat transfer coefficients can be achieved with this mechanism. In dropwise condensation, there is no liquid film to resist heat transfer, and as some result heat transfer coefficients can be achieved more than 10 times larger than those associated with film condensation, although 3-5 times is more common. Heat transfer coefficients are large so designers can achieve a specified heat transfer rate with a smaller surface area and thus a smaller and less expensive condenser.

In film wise condensation, the surface over which the vapors condense is wet-able and hence, as the distillation overhead condenses, a film of condensate is formed. Generally, film wise on condensation results in low heat transfer rates as the film of condensate impedes the heat transfer.

https://www.youtube.com/watch?v=9PBOt4kkCfU

The parts of Condensers are

1. shell used generally vapours.

2. Tube side used generally cooling water,

3. Internals are baffles, tie rode shell inlet tube inlet pass one pass or more.