Drying 227
must be changed or regenerated. The total
energy demand is lower as well (Fig. 11.9 ).
The dried air is recirculated into the drying
room (Imre 1974 ). Temperature and relative
humidity of this air is adjusted to the drying
program. This program determines the rate of
air circulation, too. The circulation is either
spraying an absorbing fl uid into the air. The
other method sends air through layers of
water - absorbing granules (e.g., silica gel).
These systems leave out the cooling and
warming of the air to achieve moisture con-
densation. The regulation of air humidity is
easier, too. However the absorbing medium
Figure 11.8. Front view (cross section) of a single level drying room.
outside
air
mixing
removal
of water
moisture and
temperature
adjustment
condensation
cooling and
condensating
warming absorbent
fluid spraying
replacement
of fluid
absorbtion
by silica-gel
regenerating
room
Figure 11.9. The arrangement of the air control unit.