Study on Drying Characteristics and Numerical Model of Turnips Based on Infrared Radiation Drying Technology

To overcome the issues of low efficiency and poor quality associated with traditional hot-air drying in turnip processing, this study employed infrared radiation drying technology to systematically investigate the effects of different temperatures (50°C, 55°C, 60°C, and 65°C) and slice thicknesses (4, 6, and 8 mm) on the drying characteristics and quality of Xinjiang turnips. Results indicate that the drying process primarily consists of a rate-decreasing stage, with drying time shortening as temperature increases and thickness decreases. The effective moisture diffusion coefficient (D_eff) ranged from 2.14 × 10^-10 to 1.14 × 10^-9 m²/s, increasing with both temperature and thickness. Activation energies for different thicknesses (4, 6, and 8 mm) were 40.90, 33.91, and 28.59 kJ/mol, respectively. Among various drying mathematical models, the Page model demonstrated the best fitting performance (R² > 0.99). Regarding turnip quality, increased temperature led to higher color difference ∆E and higher rehydration ratio, whereas increased thickness reduced both parameters. A two-dimensional axisymmetric heat and mass transfer model constructed using COMSOL yielded simulated values for dry-basis moisture content and temperature with experimental values, achieving determination coefficients R² of 0.976 and 0.952, respectively. This study provides theoretical support for optimizing turnip drying using infrared technology and advancing numerical simulation techniques.