Drying description of cylindrical pieces of bananas in different temperatures using diffusion models

• Diffusion models were used to describe drying of bananas cut into cylindrical pieces.
• In the experiments, the pieces had length of about 21 mm and radius of 15 mm, on average.
• An optimizer was coupled to the analytical solutions to determine the process parameters.
• The determination coefficients were greater than 0.9990.
• The chi-squares were less than 5.3 × 10−3 for all simulations of the experiments.

Three diffusion models were used to describe drying of bananas cut into cylindrical pieces. Analytical solutions of the diffusion equation with boundary conditions of the first and third kind were used to describe the process. In the drying experiments using hot air, the cylindrical pieces had the following dimensions: length of about 21 mm and radius of 15 mm, on average. The drying air temperatures were 40, 50, 60 and 70 °C. To determine the process parameters, an optimizer was coupled to the analytical solutions. For the best model, the effective mass diffusivities were 2.53 × 10−8; 3.12 × 10−8; 6.19 × 10−8 and 7.32 × 10−8 m2 min−1, while the convective mass transfer coefficients were 1.93 × 10−5; 3.04 × 10−5; 3.18 × 10−5 and 4.97 × 10−5 m min−1. The determination coefficients were greater than 0.9990 and the chi-squares were less than 5.3 × 10−3 for all simulations of the experiments.