ПІДВИЩЕННЯ ЕНЕРГОЕФЕКТИВНОСТІ ЗЕРНОСУШАРОК РЕКУПЕРАЦІЄЮ ТЕПЛОТИТА АДАПТИВНОЮ ЦИРКУЛЯЦІЄЮ ПОВІТРЯ

Purpose. To substantiate a promising approach to improving the energy efficiency of convective grain dryers by coordinating exhaust-air heat recovery with adaptive air-circulation control. Methodology. A review and analytical study of twenty verified scientific sources published in 2022–2026 was conducted. The publications were classified by heat-recovery method, airflow arrangement, dryer scale, control algorithm, and performance indicators. The compared indicators included specific energy consumption, specific moisture extraction rate, energy and exergy efficiencies, final-moisture non-uniformity, and the temperature margin between the coldest surface and the dew point. Results. Maximising a constant recirculation ratio was found to be an unsuitable control objective because a greater return of warm exhaust air simultaneously raises the humidity ratio of the mixed stream, condensation risk, and fan- power demand. A combined configuration is proposed comprising exhaust-air cleaning, an air-to-air heat exchanger, a controlled recirculation branch, a bypass, a final heater or heat pump, and a variable-speed fan. A two-level control structure is formulated: the lower level stabilises temperature, airflow, and pressure, while the supervisory level determines an admissible recirculation ratio from grain condition, air humidity ratio, dew-point margin, and a multi- criteria objective incorporating energy use and drying uniformity. Scientific novelty. A systemic approach has been developed in the study of drying processes, where the method of heat recovery, aerodynamic flow equalisation, and the control algorithm are treated as interdependent elements, with condensation safety imposed as an explicit constraint. Practical significance. The results specify the sensors, actuators, and performance indicators required to develop a digital model and subsequently conduct industrial tests of a retrofitted grain dryer.