Study of corn drying in a fixed bed dryer with vertical airflow using the finite volume method

This study performed the validation of a mathematical model of corn grain drying in a fixed bed and uses a bi-dimensional mathematical model based on the mass and energy conservation equations and thin layer drying equation and realizable k–ɛ turbulence model. The simulations were carried out using the commercial computational fluid dynamics (CFD) package Ansys Fluent. The deep-bed corn drying process and performance were studied by incorporating user-defined function (UDF) in Fluent. The average moisture content drying parameter were compared with experimental data obtained from literature. The validation of the mathematical model considered the coefficient of determination (R2), and the root mean square error (RMSE) and percent BIAS (PBIAS). Regarding moisture content, the measured values for the 6 experiments presented excellent agreement with the simulated values, with the value of R2 ranging between 0.998 and 0.999, and the RMSE and PBIAS values being close to zero. Moreover, the energetic and exergetic performance of deep-bed corn drying were simulated and analyzed. A comparison was made between the experimental data with the numerical results of energy efficiency: the values of R2 varied between 0.921 and 0.9420; the values of RMSE were between 0.873 and 4.544, and the values of PBIAS ranged between − 8.802 and 8.026. An energetic and exergetic analysis of the drying experiments was carried out, where the experiment, with a temperature equal to 40 °C and a velocity equal to 0.8 m/s, obtained the highest average of energy efficiency, being equal to 17.50% and the experiment with inlet temperature of 60 °C and velocity of 0.8 m/s, the highest average of exergetic efficiency, being equal to 2.47%. The simulation results showed that to reach higher exergetic efficiencies, a higher inlet air temperature and lower velocity should be applied.