Diagrams of the Moist Air Extended by Equilibrium Moisture of Dried Materials

摘要

Drying of cereals is an essential procedure in post-harvest processing. For long-term storage of cereals, it is necessary to know their sorption properties and equilibrium moisture. In the research at the Slovak University of Agriculture, the new i-w-x diagram of moist air and moist material is already applied. Moreover, the method of the immediate depiction of the moist material condition in particular environment in the i-x-w diagram is presented. The authors used Henderson's relation for equilibrium moisture of moist air and completed the i-x-w diagram with graphic representation of equilibrium moisture of the given material in the whole displayed area of nonsaturated moist air for maize, wheat, rye, barley and oats. The new characteristic parameter, drying potential Δx_p is proposed. It is calculated from the state variables derived from the i-x-w diagram. The examples of depiction of the drying process course for maize seed by the means of i-x-w diagram with drying medium temperature of 40 °C and depiction of the process with cyclic changes of drying medium flow are also provided. These new methods will enable considerably more precise modeling of various drying modes and will also improve the evaluation of control measurements at the dryers.