Thermodynamic properties for different equilibrium moisture content in sunn hemp seeds

Propriedades termodinâmicas de sementes de crotalaria

Abstract:

Losses of agroindustry are generally wet products that must be dried to posterior use and storage. In order to optimize drying processes, the study of isotherms and thermodynamic properties become essential to understand the water sorption mechanisms of agricultural products. Thus, the objective in this study was to determine and evaluate the thermodynamic properties for different equilibrium moisture contents in sunn hemp (Crotalaria spectabilis Roth) seeds, using the direct static method to obtain the experimental data. The Chung-Pfost model was used to determine the thermodynamic properties of sunn hemp seeds. In according to results, thermodynamic properties were influenced by moisture content. The water vaporization latent heat increased with the decrease in equilibrium moisture content. The sunn hemp desorption process was controlled by entropy. Gibbs free energy is negative indicating that the desorption process of sunn hemp seeds was spontaneous.

Index terms: desorption of water; latent heat; enthalpy; entropy; Gibbs free energy