Kinetic parameters identification of conductive enhanced hot air drying process of food waste

Abstract

The efficient utilization of waste from food industry is possible after thermal treatment of the material. This treatment should be economically feasible and compromise the energy efficient drying process. The main goal of this investigation is to determine drying characteristics of nectarine pomace as a waste from food industry. The measurements were performed in an experimental dryer by combined conductive-convective drying method with disk-shaped samples of 5, 7, and 10 mm thickness and 100 mm in diameter at the air temperatures of 30, 40, 50, 60, and 70 degrees C, hot plate temperatures of 50, 60, and 70 degrees C and air velocity of 1.5 m/s. The drying curves were compared to a few semi-theoretical mathematical models. The Logarithmic model showed the best correlation. On the basis of experiments, it is determined that the drying process takes place in a falling rate period and it is accepted that the main mechanism of moisture removal is diffusion. The effective coefficient of diffusion was determined using experimental results by calculating the slope of the drying curves. Drying time and equilibrium moisture are determined for each experiment. Analysis of drying curves showed that the conductive-enhanced drying method reduces drying times and increases the diffusivity coefficient. The character of drying rate curves for conductive-enhanced drying was analysed and compared with pure convective drying of nectarine pomace.