Estimation of the Diffusivities and Mass Transfer Coefficients for the Drying of D. Joaquina Pears

Portugal is a tropical country with a long tradition of drying fruits, among which stand the pears. The design of the proper operating conditions relies on the knowledge of the transfer phenomena happening during drying. Hence, the present work aimed at determining the mass transfer properties of pears for convective air drying, based on the diffusion model. The values of the diffusion and mass transfer coefficients for the drying of pears of the variety D. Joaquina were determined for two drying temperatures, 60 ºC and 70 ºC, and the results obtained showed an increase of 38 % in diffusivity and an even more pronounced increase in the mass transfer coefficient, 56 %. Regarding the dimensionless numbers, Biot number ncreased 13 % while Dincer number decrease 28 %