Download Systems Manual

2.2.1 Hot, Dry Airflow to the Water
Drying can seem difficult because there are so many things to remember. Keep this in mind though: All drying
is motivated by the same factors. Those factors are summarized by Hot, Dry Airflow, to the water. Those 4
items will dictate the quality of the drying environment that you have established. If there is a drying problem, it
will boil down to one of these factors, always!
Hot –Heat the surfaces that are wet and you heat the water at that surface. This
increases the vapor pressure of that water which helps speed drying.
Contain heat to the wet surface since it wants to rise and the water seeks the lowest
level.
Dry – Dry the air at the wet surfaces. Lower the specific humidity or the vapor pressure of the
air at a wet surface. Dry the air as much as possible to speed evaporation.
This is done using dehumidification or ventilation to remove some of the water from the air.
Air Flow – Move air over the water to speed energy transfer into the moisture.
Just like blowing on coffee that is too hot speeds the cooling process, speeding air flow in a
drying environment warms surfaces that are evaporating and therefore cooling.
Air flow is a multiplier of vapor pressure differentials according to Dalton’s Law of
Evaporation.
To The Water – Get the hot, dry airflow as close to the water as possible. This means eliminating moisture
barriers and unnecessary layers of materials. The closer you get these elements to the water, the faster
evaporation will occur. If there is a moisture barrier, evaporation will not occur. Think of a pot of boiling water
with the lid on it.
By improving one or any combination of the above causes, you will improve your drying environment. For a
better understanding of how to measure Hot and Dry, look at the Evaporation Potential systems in our manual.