Drying of Food Products Shaped as Longitudinal Sections of Solid and Annular Cylinders: Modeling and Simulation

A mass transfer model was proposed to describe the moisture evolution during drying of longitudinal sections of solid and annular cylinder-shaped food products. The dimensionless form of the model was numerically solved under the resulting combinations of two geometrical parameters (inner radius and angular cuts) to produce longitudinal sections of solid and annular cylinders. In addition, average drying curves were calculated from the volume integration of local moisture values. A mixed theoretical and numerical approach was used to develop the dimension similarity between the studied geometries and a simpler flat slab-shaped product in order to obtain an approximate analytical solution to the original, non-steady-state mass transfer problem, while an exact solution was also developed to highlight problem complexity. In order to validate actual results during water diffusivity estimation, potatoes were chosen as the food model, as this product can be easily shaped into either studied or traditional geometry with known solution. Different cuts (parallelepiped and longitudinal sections of both solid and annular cylinders) were obtained and air-dried (80°C, 2.5 m/s). In this regard, a simple method to estimate diffusion coefficients in 2D or 3D geometries is also presented. Under the described experimental conditions, water diffusivities for each geometry were estimated in the narrow range of 1.27–1.52 × 10−9 m2/s, demonstrating the applicability of the proposed approach to solve mass transfer problems in products described by geometries lacking simple analytical solutions.