LOW-TEMPERATURE MOISTURE TRANSFER CHARACTERISTICS OF WHEAT IN THIN-LAYERS

Wheat was dried in thin layers in the temperature range 3.5 to 23.4 de grees C, with additional points at 30.4, 40.2, and 49.7 degrees C for comparison with previous work. Each sample was dried for about one wee k. The exponential Newton model was fitted to the data and the resulti ng drying constant fitted to the Arrhenius equation to describe the te mperature effect. The solution for diffusion in a sphere was also fitt ed giving the diffusivity, which was again fitted to the Arrhenius equ ation. The diffusion model [standard error = 0.0031 db. (dry basis)] f itted the data better than the Newton model (standard error 0.0067 db. ). The fitted dynamic equilibrium moisture content was compared with p revious static equilibrium moisture content data and was generally hig her, as would be expected for a dynamic value. The results are particu larly relevant to moisture transfer during the cooling of stored grain , which provides a useful alternative to pesticide use.