Drying of wheat grain in a fluidized bed

The decrease of grain humidity during drying of the grain in a fluidized bed is accompanied by a rapid increase in its temperature to the maximum permissible 60°C. Further drying leads to overheating of the grain. From previous studies, it is clear that the most difficult point in the experimental determination of the heat transfer coefficient between the grain and the drying agent in the fluidized bed is to measure the temperature of individual grains in real mode. It is experimentally established that the grain temperature throughout the entire volume of the drying chamber in the fluidized bed is constant (except for the space near the gas distribution grid) and with a small error is equal to the temperature of the spent drying agent. Therefore, studies on the influence of technological parameters of the drying process on the heating of grain were conducted at the temperature of the spent drying agent. The analyze of the thermal resistance during heat exchange between the grain and the drying agent in the fluidized bed is performed in the article. The effect of the effective heat exchange surface between the grain and the drying agent on the heat transfer coefficient is described. The technological parameters of the experimental grain dryer are justified, the optimal values of these parameters are determined; the influence of the air flow temperature and the duration of the technological process on the heating temperature of the grain layer is studied.