Linear tunnels are restricted by the length of belt necessary to achieve the
cooling time required and on the space available. Conveyors wound into a
spiral shape and contained within a cold-room with an air blast coil offer a
more compact arrangement (see Figures 14.1 and 14.2 ). Spiral freezers are
very good for larger items, such as tubs of ice-cream which take a long time to
harden and where a straight conveyor would be too long for convenience