A new approach to the traditional drying models for the thin‐layer drying kinetics of chickpeas

The drying process is an essential step in the postharvest of grains. The objective of this research was to study the drying kinetics of chickpeas (Cicer arietinum L.), by introducing a new approach to simplify the Fick equation. Drying temperatures of 40, 50, 60, 70, and 80°C were used in a hot air convective dryer to dry thin‐layers of chickpeas. The mathematical models (Fick, modified Henderson & Pabis, modified Page, and Cavalcanti‐Mata) were fitted to the experimental data. Using the effective diffusivity calculated from each model, the activation energy was determined, as well as the thermodynamic properties of the process. Drying times ranged from 72,000 to 39,600 s and correlated negatively with temperature. The semiempirical models presented a better fit to the experimental data than the Fick theoretical model with six terms. Effective diffusivity varies according to each model with values ranging from 54.0 × 10−11 to 78.0 × 10−11 m2/s depending on the drying temperature. Enthalpy (4.99 kJ/mol) and entropy (−0.27 kJ mol−1 K−1) values decrease with increasing temperature revealing that increasing drying temperature the less overall energy is expended and more heterogeneity is found. Gibb's free energy (102.8 kJ/mol) is directly proportional to temperature. Thus, the drying process is not spontaneous. Practical applications Drying models allow prediction of drying times and thus process and equipment design. Therefore, optimal drying models are required to improve these industrial tasks. Our work can be used to improve the process and equipment design by the improved drying models. Additionally, estimation of the process thermodynamic properties provides insights to use the drying energy better.