Mathematical Model of Thin Layer Drying of Purple Yam by Infrared Assisted Heat Pump Drying

This study focused on the thin-layer drying of yam by infrared-assisted heat pump drying to determine the thin-layer drying model, the effective moisture diffusivity, and the activation energy of moisture within the yam. The thin-layer drying experiment was conducted with input drying parameters such as drying temperatures of 40, 45, and 50°C, drying air velocity of 2.5 m·s⁻¹, and infrared power of 250, 300, and 350 W. In order to determine a suitable thin-layer drying model for describing the yam drying process, six different thin-layer drying models (Lewis, Page, Modified Page, Henderson and Pabis, Wang and Singh, and Midilli) were chosen for nonlinear regression with the experimental drying data. The Midilli model was found to be the most suitable drying model for describing the thin-layer drying of yam. The average effective moisture diffusivity was in the range of 4.184×10⁻⁹ to 8.142×10⁻⁹ m²·s⁻¹, and the activation energy was in the range of 16.78 to 21.01 kJ·mol⁻¹ over the proposed range of drying input parameters