Solar‐tracking PV ‐assisted hybrid drying for low‐carbon apple dehydration: Energy–exergy performance and CO 2 mitigation

Abstract This study experimentally evaluated a solar‐tracking PV‐assisted hybrid dryer for low‐carbon apple dehydration through an integrated assessment of drying kinetics, energy and exergy performance, auxiliary grid‐electricity demand, and operational CO 2 mitigation. The system combined a single‐axis tracking flat‐plate solar air collector, a separate PV‐powered ventilation and control subsystem, a 5‐kW auxiliary electrical heater, and a forced‐convection drying chamber. Red Delicious apple slices of 3 and 6 mm thickness were dried at 0.5, 1.0, and 1.5 m s −1 under a nominal drying‐air temperature of 50°C. Increasing air velocity accelerated moisture removal, reducing drying time from 240 to 135 min for 3‐mm slices and from 300 to 180 min for 6‐mm slices, but increased the auxiliary electrical requirement. The lowest airflow provided the greatest grid‐energy displacement relative to the analytically estimated fully electrical baseline, with electrical energy reduction ratios of 86.39% and 87.15% for 3‐ and 6‐mm slices, respectively. The maximum avoided operational emission reached 1.334 kg CO 2 batch −1 for 6‐mm slices at 0.5 m s −1 , whereas the highest specific carbon saving was 2.899 kg CO 2 kg −1 dried product for 3‐mm slices under the same airflow condition. Exergy analysis further characterized the thermodynamic performance of the tracking collector and the physical exergy behavior of the drying‐air stream across the chamber. Overall, the investigated configuration demonstrated a clear operating trade‐off between rapid dehydration and reduced auxiliary grid‐electricity demand, with low airflow favoring carbon mitigation and higher airflow favoring shorter processing time.