Drying kinetics and inversion temperature in a low-pressure superheated steam-drying system

The present study aimed at investigating the drying rates and inversion temperatures of model porous particles undergoing low-pressure superheated steam and vacuum drying. Molecular sieve beads, which were used as the model material in this work, were dried as a single layer in a low-pressure superheated steam dryer. The effects of steam temperature and pressure on the drying rates of these particles were determined. The same dryer was also operated in a vacuum mode to determine the effects of the above-mentioned operating parameters as well as the variation of the inversion temperature of the processes with the operating pressure. The differences between the values of the inversion temperature calculated only from the rates of drying in the constant rate period and those calculated from the whole drying period are pointed out and discussed. Page's equations and a single-term exponential equation were found to satisfactorily describe the kinetics of low-pressure superheated steam- and vacuum-drying systems, respectively.