Question

What is condensation? What are the forms of condensation?​

Answer 1

• Condensation is the change of the physical state of matter from the gas phase into the liquid phase, and is the reverse of vaporization. The word most often refers to the water cycle.

• After condensation the water vapour or the moisture in the atmosphere takes one of the following forms — dew, frost, fog and clouds. Condensation takes place when the dew point is lower than the freezing point as well as higher than the freezing point.

Answer 2

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What is condensation? What are the forms of condensation?​

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☆What is condensation?

• Condensation is the change of the physical state of matter from the gas phase into the liquid phase, and is the reverse of vaporization. The word most often refers to the water cycle. It can also be defined as the change in the state of water vapor to liquid water when in contact with a liquid or solid surface or cloud condensation nuclei within the atmosphere. When the transition happens from the gaseous phase into the solid phase directly, the change is called deposition.

☆What are the forms of condensation?​

In general, three distinct forms of condensation are observed:-

✧Film condensation.

• In film condensation, the condensate wets the surface and forms a liquid film on the surface that slides down under the influence of gravity.

• Film condensation results in low heat transfer rates as the film of condensate impedes the heat transfer.

• The thickness of the film formed depends on many parameters including orientation of the surface, viscosity, rate of condensation etc.

• The film increases a thermal resistance to heat flow between the surface and the vapour.

• The rate of heat transfer is reduced because of this resistance.

✧Dropwise condensation

• In dropwise condensation, the condensed vapor forms droplets on the surface instead of a continuous film.
• Dropwise condensation can occur when the surface is nonwetting or these droplets are taken away from the surface by external flow or by gravity.

✧Direct contact condensation.

• Direct contact condensation, DCC, occurs when vapor is brought into contact with a cold liquid.
• As in jet condensers, the cooling water is sprayed on the exhaust steam and there is direct contact between the exhaust steam and cooling water.
• The process of condensation is very fast and efficient, but here cooling water and condensed steam are mixed up.
• The advantages of direct contact condensation over the conventional processes using metallic transfer surfaces are due to the relative simplicity of design, less corrosion and scaling problems, lower maintenance costs, higher specific transfer areas, and higher transfer rates.
• Despite these advantages jet condensers are not usual in thermal power plants especially due to the loss of condensate.

Happy Learning dear!!♡