Moist compressed air flows into the module housing where it comes into contact with the membrane fibres. A minimal amount of this now dry compressed air is used as purge air and is drawn upwards around the fibres and expands to atmospheric pressure. The resulting increase in volume increases the air’s water retention capacity. In combination with with the selectivity of the membrane, the differing water content of the purge air flow and the flow of air to be dried (both fl owing in opposite directions), allows water molecules – almost exclusively – to diffuse through the fibre wall.
There are separate outlets for the dried compressed air and the purge air.