<P> The Leidenfrost Effect demonstrates how nucleate boiling slows heat transfer due to gas bubbles on the heater's surface . As mentioned, gas - phase thermal conductivity is much lower than liquid - phase thermal conductivity, so the outcome is a kind of "gas thermal barrier". </P> <P> Condensation occurs when a vapor is cooled and changes its phase to a liquid . During condensation, the latent heat of vaporization must be released . The amount of the heat is the same as that absorbed during vaporization at the same fluid pressure . </P> <P> There are several types of condensation: </P> <Ul> <Li> Homogeneous condensation, as during a formation of fog . </Li> <Li> Condensation in direct contact with subcooled liquid . </Li> <Li> Condensation on direct contact with a cooling wall of a heat exchanger: This is the most common mode used in industry: <Ul> <Li> Filmwise condensation is when a liquid film is formed on the subcooled surface, and usually occurs when the liquid wets the surface . </Li> <Li> Dropwise condensation is when liquid drops are formed on the subcooled surface, and usually occurs when the liquid does not wet the surface . </Li> </Ul> </Li> </Ul>

A is a material that transfers heat well