From laboratory experiments to design of a conveyor-belt dryer via mathematical modeling

A conveyor-belt dryer for picrite has been modeled mathematically in this work. The necessary parameters for the system of equations were obtained from regression analysis of thin-layer drying data. The convective drying experiments were carried out at temperatures of 40, 60, 80, and 100°C and air velocities of 0.5 and 1.5 m/sec. To analyze the drying behavior, the drying curves were fitted to different semi-theoretical drying kinetics models such as those of Lewis, Page, Henderson and Pabis, Wang and Singh, and the decay models. The decay function (for second order reactions) gives better results and describes the thin layer drying curves quite well. The effective diffusivity was also determined from the integrated Fick's second law equation and correlated with temperature using an Arrhenius-type model. External heat and mass transfer coefficients were refitted to the empirical correlation using dimensionless numbers (J h , J D = m · Re n ) and their new coefficients were optimized as a function of temperature. The internal mass transfer coefficient was also correlated as a function of moisture content, air temperature, and velocity

From laboratory experiments to design of a conveyor-belt dryer via mathematical modeling

A conveyor-belt dryer for picrite has been modeled mathematically in this work. The necessary parameters for the system of equations were obtained from regression analysis of thin-layer drying data. The convective drying experiments were carried out at temperatures of 40, 60, 80, and 100°C and air velocities of 0.5 and 1.5 m/sec. To analyze the drying behavior, the drying curves were fitted to different semi-theoretical drying kinetics models such as those of Lewis, Page, Henderson and Pabis, Wang and Singh, and the decay models. The decay function (for second order reactions) gives better results and describes the thin layer drying curves quite well. The effective diffusivity was also determined from the integrated Fick's second law equation and correlated with temperature using an Arrhenius-type model. External heat and mass transfer coefficients were refitted to the empirical correlation using dimensionless numbers (J h , J D = m · Re n ) and their new coefficients were optimized as a function of temperature. The internal mass transfer coefficient was also correlated as a function of moisture content, air temperature, and velocity

Common applications of thin layer drying curve equations and their evaluation criteria

In this study, thin layer drying curve equations commonly used in the literature between 2003 and 2013 are systematically discussed and evaluated in terms of their applications and selection for thin layer drying processes by considering the model evaluation criteria. As a result of this study, serious complications, confusions, and conflicts in the applications of thin layer drying curve equations and their evaluation criteria are noticed. Consequently, it is recommended that the drying curve equations should be applied in accordance with the forms commonly used in the literature. Also, it is determined that the following drying curve equations give the best results for thin layer drying processes which are the Midilli-Kucuk, Page, Logarithmic, Two-term, Wang and Singh, Approximation of diffusion, Modified Henderson and Pabis, Modified Page, Henderson and Pabis, Two-term exponential, and Verma et al. © Springer International Publishing Switzerland 2014