Thin Layer Drying Kinetics and Mathematical Modeling of Moisture Diffusivity in Cocoa Pod Husk (CPH)

Abstract

Cocoa pod husk (CPH), an agricultural by-product of the cocoa separation process, contains an average moisture content of 5.40 ±0.05 kg_water/kg_{dry matter}. Drying characteristics of CPH were examined in hot air at 50, 60 and 70°C using a laboratory oven with air ventilation at 3 L/min and a load cell sensor (HX-711) was used for weight loss tracking. Twelve mathematical models simulated the drying rate from a drying curve at each operating temperature by comparing four statistically calculated parameters. Levels of variation were investigated by plotting experimental data against the predicted moisture ratios to identify the sum of residuals and obtain a good fit. The Midilli et al. model provided the best drying characteristics with optimized statistical parameters. Using an Arrhenius type relationship, the effective diffusivity coefficient of moisture transfer varied from 7.979 x 10^-10 to 13.298 x 10^-10 m²/s, with operating temperature set at 50, 60 and 70°C and activation energy for moisture diffusion 70.48 kJ/mol.