Abstract
The flow conditions of a new dryer for by-product of tofu proposed in the previous paper are examined. Its drying capacity is relatively small and to know the internal flow is necessary to develop larger capacity machines. Firstly, the interior of drying drum and classifying chamber were observed using high speed video. Wet materials returning from upper chamber are colliding with the materials and ceramic balls moving along the surface of the drying drum entrained in the hot air and dispersed. In the classifying chamber counterclockwise circulating flows are formed. Then numerical simulation was carried out for the flow of this dryer using FLUENT. Necessary nodes were about 800,000 to describe the whole machine. Obtained path lines are almost consistent with the video images showing the validity of the simulation method. To get the suitable geometry for 5 times larger machine, flow conditions were compared for three types of geometry of the entrance to classifying chamber and the best geometry was determined. The chamber height was then determined so that the velocities at the ceiling are below 3 m/s to avoid adhesion of the wet materials to the wall. Based on the obtained results 300 kg/h machine was build and it was successfully operated.
