Abstract
Drying of fragile granules of bulk materials has to be carried out in a fixed bed to prevent particle damage. This way of drying protects the granules, but the lack of mixing of the particles leads to an uneven distribution of heat and mass transfer conditions in the bed. It is necessary to be able to predict the distribution of drying conditions inside the bed to select a rational drying mode. In this paper, a mathematical model for drying bulk media in a fixed bed is proposed, its parametric identification is carried out, and the model is verified by comparison with experimental results. The numerical model is based on explicit difference schemes using the mathematical apparatus of Markov chains. The experimental study was carried out on a laboratory dryer with the detection of local drying parameters according to the height of the fixed bed. The numerical and experimental results were obtained at the fixed temperature (90 °C) and gas velocity (0.5 m∙s−1). It has been shown that at a certain bed height, areas with relative gas humidity above 100% are formed within it, which negatively affects the efficiency of the drying. The proposed model allows identifying the indicated ineffective drying modes, and has proven to be a reliable tool for predicting the moisture ratio of the material with an MAPE of less than 7%.