DETERMINATION OF HEAT-TRANSFER COEFFICIENTS DURING DRYING OF FOODSTUFFS

Heat transfer coefficients during drying of foods were evaluated from drying data and heat and mass balances. Experimental drying curves for slices and cylinders of potato, apple and carrot were obtained in a laboratory dryer under different drying conditions. The specific heat of the foodstuffs was measured as a function of water content and modelled through a linear relationship. Experimental heat transfer coefficients were correlated by the dimensionless expression Nu(D) = 0.249 Re-D(0.64) and compared with predictions of different equations.