What a great day for culture on the list! Avogadro's number and Vanagon in
the same dissertation! There is hope for our society yet. Even the mere
mention of the mole was gave a tingle in the cranium surprisingly similar to
an ounce of Cointreau on ice.

Nonetheless, Stan, Ed and Arlan are all quite correct ... humid air is less
dense than dry. Also, the extraction or heat transfer ability of the flowing
gas is related primarily to temperature and secondarily to velocity , then to
turbulence and finally to macroscopic porosity or surface area per unit areal
dimension.

However, this is not the case when the water has not been fully atomized.
Small water droplets (can range from nanoclusters to sub-mm aerosols) offer
the ability to volatilize (get to use the heat of vaporization). This can
significantly enhance net thermal transport and reduce chamber detonation.
Taken to the extreme, a thin layer of water (2 to 4 monolayers) on the
radiator surface at the turbulent air boundary will give superb heat transfer
. Of course, one needs to keep the water film thickness below the level where
the bulk thermal conductivity of the water would dominate. Such thickness
control is generally beyond the ability of most practitioners of the
automotive arts!

BTW a thin film of Cointreau would work wonderfully as well; what a fine
aroma, but what a waste.

Have a chemically interesting day!

Frank Grunthaner