lFigures 30.2(a) and 30.2(b) show examples of tunnel dryers. As
illustrated, the heated drying air is introduced at one end of the tunnel and
moves at an established velocity through trays of products being carried on
trucks. The product trucks are moved through the tunnel at a rate required to
maintain the residence time needed for dehydration. The product can be moved
in the same direction as the air flow to provide concurrent dehydration (Fig.
30.2(a)), or the tunnel can be operated in counter current manner (Fig. 30.2(b)