Effect of convective and infrared drying on kinetics, activation energy, and quality of eggshells reinforced kaolin composites: Comparative study

Abstract

The present work is focused on the influence of convective (CV) and Infrared (IR) drying of a novel bio-ceramic material, namely, Eggshells (ES) reinforced kaolin (K) composite, on the drying kinetics, moisture distribution, the effective moisture diffusivity and activation energy as well as the quality and the mechanical strength of the dried product. CV and IR drying experiments were carried out at four temperatures (60, 70, 80, and 90 °C), and different ES content varied from 20 to 50 wt%. The evolution of the moisture ratio and drying rate has been assessed to study the CV and IR drying kinetics of the prepared composites. Moisture diffusivity data and activation energy, determined from experimental drying kinetics, were reported. Based on the obtained results, temperature and ES content had a positive effect on drying kinetics and moisture diffusion. Compared to the CV mode, IR drying decreased the drying time, accelerated the drying process at lower energy consumption, and enhanced the moisture content distribution. The highest moisture diffusivity coefficient (Deff) values inside the bio-composites were achieved using an IR dryer. At 90 °C, K-50%ES dried in an IR dryer showed rapid drying kinetics (40 min) and moisture diffusivity coefficient of 5.88 × 10-6 m2/s, a low activation energy of 52.74 KJ/mol, and better moisture diffusion inside the composite. Nevertheless, the best quality of the dried product K-50%ES was achieved at a mild drying temperature (60 °C). IR drying showed the best results in terms of preserving time, kaolin material and energy consumption during bio-composite drying.