HEAT AND MASS TRANSFER CHARACTERISATION OF MICROWAVE DRYING OF LEATHER

摘要

The characteristics of microwave-assisted drying of chrome tanned leather are studiedrnfor several air flow and microwave power conditions. Drying rates and temperaturernevolution of leather are presented and a physical model is proposed in order to explainrnthe behavior of this material under microwave radiation. In this model, it isrndemonstrated that the precise knowledge of the dielectric properties is essential tornproperly determine the temperature evolution and drying rate acceleration.rnDifferent experimental tests have been carried out in order to demonstrate the localrnmoisture leveling when microwave assisted drying is applied to leather hides. Severalrnsamples with different initial moisture contents were dried, and at the same time, theirrnmass loss and temperature progress measured. Drying curves showed a fastrnconvergence as a proof of this effect. For this purpose, a microwave equipment wasrndesigned, built and used to carry out the different tests. The obtained results lookrnpromising as the drying rates are highly accelerated without damaging the leather tissue.rnAdditionally, a more uniform moisture distribution along the hide was obtained.