In order to create a driving force for water permeation, the permeate
pressure must be lower than the partial water vapor pressure
in the feed air. Due to the small partial pressure of water
vapor in the air, the driving force for water vapor permeation is
small. Therefore, in order to obtain significant moisture removal,
the membrane must have high water vapor permeance and the
permeate pressure must be very low. However, it is important to
select an optimal operation pressure at which a reasonable amount