Grains are to be handled/dried in huge bulks and loading/ unloading of such huge bulks into/ out of large number of trays may be a big limitation. Moreover, the grain bed in the tray will remain static and will not be desirable from the heat transfer point of view. making the bed too thin will necessitate the use of a large number of trays still worsening the handling as well as economy. Fluidization of grains in trays will involve excessive energy requirement.
For large scale commercial application, LSU dryers, being continuous/ free flowing/ mixing type/ thin layer/ economic, are among the most preferred ones. Other designs based on similar criteria may also be used.