4. Intensification of exchanges during condensation of a vapour phase

The exchange mechanisms involved in a condenser are considerably less complex than those of an evaporator. Two dominant condensation modes are encountered:

• film condensation, the most common mode, which results in the formation of a film of condensate with a relatively homogeneous distribution on the cold wall; this film of condensate flows down the wall due to the force of gravity (falling or trickling film) or due to interfacial stresses with the vapor phase if its velocity is high. This condensation mode is characterized by exchange coefficients that depend on the physical properties of the film, the flow configuration if condensation takes place in a channel, and the interactions between the condensate and the vapor. For condensate in the laminar regime of pure steam, thermal resistance is exclusively constituted by the thickness of the...