Energy performance assessment of solar dryers with natural convection, forced air extraction, and thermal storage: a case study under Andean Amazonian transitional climate conditions

This study evaluates the energy performance of three solar drying systems operating under the climatic conditions of Chachapoyas, Peru: a natural convection dryer (D0), a dryer with non-continuous forced-air extraction (D1), and a forced-air dryer incorporating thermal energy storage using river sand in the collector (D2). The systems were operated simultaneously under identical environmental conditions. The experimental evaluation was conducted over a 30-day period between July and September 2025, with monitoring from 06:35 to 18:17 h at 5-minute intervals. Solar radiation, ambient conditions, and temperature profiles were recorded using an Arduino-based data acquisition system. Available solar energy ranged from 1589.56 to 6047.25 Wh·m⁻². The system with thermal storage (D2) achieved the highest mean thermal efficiency (46.04 ± 11.66%), followed by D0 (45.82 ± 10.45%), while D1 showed the lowest efficiency (39.67 ± 10.08%). Thermal storage improved energy stability and reduced sensitivity to solar variability conditions overall.