KINETIC DRYING EXPERIMENTAL DATA AND MATHEMATICAL MODEL FOR SWEET CHERRIES (PRUNUS AVIUM)
Models for food particle and dryer design should be as simple as possible. A dryer can be visualized as formed by a number of thin layer beds, ideally one particle deep. Therefore, thin-layer dehydration studies are an essential step to developing methods for industrial equipment design. In this work, drying curves were experimentally determined for sweet cherry fruits, using air temperatures of 50, 60, 70 and 80C; air relative humidities of 5 and 50%; and air velocities of 1, 2, 3 and 5 m/s. A short time analytic predictive model for diffusion inside solids, fast to run on the computer, was selected to interpret the data with satisfactory accuracy. By this fitting procedure, diffusion coefficients of water in sweet cherries were determined to vary between 6.814 × 10−11(50C) and 3.474 × 10−10(80C) m2/s. The relationship of diffusivities with temperature was accounted for by using an Arrhenius-type equation. PRACTICAL APPLICATIONS
The determination of intrinsic drying properties such as thin layers, which are kinetic parameters, becomes an important issue as far as industrial dryer design is concerned. In thin-layer-dryer analyses, the food particle whose transport (drying) properties need to be evaluated is exposed to constant drying air conditions for a given length of time, so all variations occur within the product, and so the drying parameters thus measured can be related to those constant air conditions. The conclusions obtained at the thin-layer level, which are interesting in themselves as drying information, must be consistent enough to allow their application at the deep-bed level, for equipment simulation and design. Therefore, thin-layer dehydration studies are an essential step to developing methods for industrial equipment design.
Document Type: Research Article
Affiliations: Asentamiento Universitario Villa ReginaFacultad de IngenieríaUniversidad Nacional del ComahueReconquista y 25 de Mayo – (8336) Villa Regina, Río Negro, Argentina
Publication date: 2010-12-01