Editing Recuperator (section)

==Energy transfer process==
Normally the heat transfer between airstreams provided by the device is termed as "[[sensible heat]]", which is the exchange of energy, or [[enthalpy]], resulting in a change in temperature of the medium (air in this case), but with no change in moisture content. However, if moisture or relative [[humidity]] levels in the return air stream are high enough to allow condensation to take place in the device, then this will cause "[[latent heat]]" to be released and the heat transfer material will be covered with a film of water. Despite a corresponding absorption of latent heat, as some of the water film is evaporated in the opposite airstream, the water will reduce the [[thermal resistance]] of the [[boundary layer]] of the heat exchanger material and thus improve the [[heat transfer coefficient]] of the device, and hence increase efficiency. The energy exchange of such devices now comprises both sensible and latent heat transfer; in addition to a change in temperature, there is also a change in moisture content of the exhaust air stream.

However, the film of condensation will also slightly increase pressure drop through the device, and depending upon the spacing of the matrix material, this can increase resistance by up to 30%. If the unit is not laid to falls, and the condensate not allowed to drain properly, this will increase fan energy consumption and reduce the seasonal efficiency of the device.