Shrinkage effect on diffusion coefficient during carrot drying
¹Latvia University of Life Sciences and Technologies, Faculty of Engineering, Institute of Agricultural Machinery, J.Cakstes Blv 5, LV-3001 Jelgava, Latvia
²Latvia University of Life Sciences and Technologies, Faculty of Information Technologies, Department of Computer Systems, Liela 2, LV-3001 Jelgava, Latvia
Many studies have been previously carried out on the carrot drying and the undergoing processes. The developed mathematical models provide an opportunity to gain an understanding of this complex process and its dynamics. But they are simplified and based on a number of assumptions, including calculation of diffusion coefficient values. In one of the previous studies, the authors of this study determined that the diffusion coefficient is linearly dependent on the moisture concentration with the assumption that the sample’s geometric shape does not change. The aim of this study is to determine the dependence of the diffusion coefficient on the moisture concentration taking into account the change in sample thickness during the drying experiment. The experiments were carried out with carrot slices of three different thicknesses: 5 mm, 10 mm and 15 mm thickness on the film infrared dryer at temperature 40 °C. During the experiments, measurements of the weight and thickness of the slices were performed. Using the experimental data the average thickness and diffusion coefficient of slices was calculated depending on the moisture concentration. Obtained results show that thickness depends linearly on the moisture concentration. Using experimental data and obtained average values of samples thickness, the values of diffusion coefficient was calculated. The results indicate that diffusion coefficient value depend linearly on moisture concentration. Their values are close and tend to zero when the concentration decreases if the thickness changes are taken into account during the experiment.