CFD simulation of heat and mass transfer during apricots drying

Abstract

A heat and mass transfer model has been developed to highlight, by CFD (Computational Fluid Dynamics) simulation, the moisture and temperature gradients in convective drying process of apricots. The drying simulation was performed for the unsteady flow regime, for unblanched and blanched apricots, by following the moisture content and the temperature from the boundary layer and pulp. The apricots were represented with a geometry that doesn't change over time, and their pulp as a homogenous and isotropic vegetable material. The dryer–apricot model discretisation was hybrid. The heat and mass transfer model was linked to the CFD simulation by UDF (User Defined Functions), using functions for the physical properties of apricots and warm air, which vary with time. The apricots were dried with warm air, using a system which allowed the monitoring and adjustment of air velocity and temperature. During the experiments the warm air parameters were as follows: air velocity of 1 m/s, air temperature of 353 K, drying time 2.5 h. The blanching of apricots was performed by immersion into water at a temperature of 363 K, for 120 s. Several data obtained by the experiment of drying process were included into CFD simulation. The final moisture and temperature results obtained by simulation and experiment were compared, with the purpose to evaluate the accuracy of the drying model, for blanched and unblanched apricots.