The drying apparatus includes a drum rotatably arranged in an outer box with a certain distance spaced from the inner surface of the outer box and housing therein materials to be dried. An air supply device supplies heated air into the drum, and a moisture removing device cooles air discharged from the...http://www.google.fr/patents/US4516331?utm_source=gb-gplus-shareBrevet US4516331 - Drying apparatus having recycle air path
