Activation energy kinetics in thin-layer drying of onion

Abstract

The goal of this work was to look at the drying kinetics of onions (Allium cepa L.) and calculate the effective moisture diffusivity and diffusion activation energy. The test was carried out in a constant temperature and humidity test chamber at various temperatures with a relative humidity of 15%. At air temperatures of 45 °C, 50 °C, and 55 °C, the drying time required to reduce the moisture content of onion from 81 percent (wb) to 8 percent (wb) was 23, 19, and 17 hours, respectively. The Henderson-Pabis drying model was used to fit the experimental results to determine the diffusion activation energy (Ea) of onion. Ea was computed as 23.03 kJ/mol. When the drying air temperature was increased from 45 °C to 55 °C, the effective diffusivity of the onion increased from 1.85 109 m/s to 2.42 109 m2/s.