This Air dryer is similar to the Internal Heater type air dryer except that no process air is wasted. For regeneration of the Desicant bed , a blower provides the atmospheric air which is pre-heated in an external heater upto 160 deg C, to regenerate the desiccant bed.
Therefore no process air is used for regeneration. The unit is fully automatic / semi-automatic .
The desiccant used is normally Silica gel or Activated alumina.