Abstract

This study explores the design, CFD simulation, experimental validation, exergy, and economic performance of a natural convection solar tunnel dryer for drying maize ears. The dryer, designed to address postharvest losses and promote sustainable drying practices, has a capacity of 114.2 kg and a total area of 5.0 m². It reduced the maize moisture content from 23.4% to 12.5% (wet basis) in 5 days, compared to 12 days under open sun drying. Experimental performance closely aligned with CFD simulations performed using SOLIDWORKS 2023, which predicted airflow and heat transfer.

The dryer effectively heated the air from an average of 25°C at the inlet to 55°C at the collector’s outlet end. The central and top sections exhibited the highest temperatures due to direct solar radiation, while slight cooling occurred near the outlet as heat was absorbed by the drying material and lost through convection and radiation. The chimney, designed as a vertical solar collector, enhanced airflow by increasing buoyancy pressure.

Exergy analysis identified losses due to irreversibility, suggesting chimney design modifications to improve airflow and exergy utilization. Economically, the dryer offered a payback period of 3.7 years, demonstrating its value in preventing postharvest losses and enhancing food safety.

This integrated approach highlights the feasibility and sustainability of natural convection solar dryers as effective solutions for postharvest maize drying, particularly in regions with similar climatic conditions.

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