ber wheel was powered by an electrical motor to rotate the drum
counterclockwise at 8.12 Rev/h speed.
Fresh air was delivered by a fan to the electrical resistant heater.
The air was heated to the desired temperature was then forced
through the bottom of thedrumvia a connection pipe (25-cm diameter),
with the air distribution unit enclosing 1/3 part of the drum.
The material to be dried was placed into the drum by hand. The
rotational speed of the fan and the rotational speed of the drum
could be separately adjusted by electronic speed variator. The fan
speed was adjusted to supply air at an average volumetric flowrate
of 515m3 h−1. Volumetric flowrate of the heated air was measured
by a hot-wire anemometer (Testo 425, Germany) in placed in the
connector pipe. Temperature of the heated air was controlled using
a Pt100 temperature sensor and an electronic controller (Elimko
210, Turkey) which adjusted the electrical energy supplied to the
heater to maintain the desired air temperature.