The effect of the recirculation coefficient of the drying agent on its temperature in the aerodynamic heating dryer

BACKGROUND: The expansion of the functionality of chamber dryers of aerodynamic heating is possible by equipping them with additional modules, for example, in the form of a drying shaft for grain. However, it is necessary to ensure the implementation of the basic principle of operation of aerodynamic heating dryers – recirculation of the drying agent with its partial discharge during the drying process. AIM: Determination of the dependence of the temperature of the drying agent on the recirculation coefficient of the spent drying agent when using an additional module in the form of a drying shaft for grain. MATERIALS AND METHODS: A differential equation was obtained from the heat balance equation of the dryer in an infinitesimal period of time, as a result of solving which the desired dependence was found by the second-order Euler method. Graphs of the temperature change of the drying agent during the grain drying process are constructed for the accepted initial data with a value of the recirculation coefficient equal to 0.3, 0.5, 0.7 and the moisture content of the spent drying agent equal to 0.012 and 0.041 kg/kg d.a. RESULTS: The analysis of the dependencies showed that the temperature of the drying agent increases with an increase in the recirculation coefficient and moisture content of the drying agent. The maximum possible temperature of the drying agent for a recirculation coefficient equal to 0.3 will be 135 °C, for a recirculation coefficient equal to 0.5–158 ° C, for a recirculation coefficient equal to 0.7–198 ° C. Maintaining the set temperature of the drying agent is ensured by adjusting the recirculation coefficient of the spent drying agent by changing its flow rate in the recirculation channel. CONCLUSION: The dependence obtained on the basis of the heat balance of the dryer makes it possible to predict the temperature of the drying agent depending on the established recirculation coefficient of the spent drying agent at a given range of changes in its moisture content. At the same time, the operating mode of the aerodynamic heating dryer is ensured even when using its additional modules.