Solar Air Heaters for Agricultural Drying: A Comprehensive Review

Abstract

Agricultural products, particularly perishable commodities, require efficient post-harvest drying techniques to reduce losses and preserve quality. Traditional drying methods, such as open sun drying, are often inefficient and prone to contamination, making solar air heaters (SAHs) a promising alternative. This study reviews the design, development, and performance analysis of various solar air heater configurations used for agricultural drying. Key parameters influencing the efficiency of SAHs—such as collector design, air flow rate, absorber materials, and insulation—are examined. The paper highlights the advantages of indirect and direct drying techniques using SAHs and evaluates their thermal performance under different climatic conditions. Further, it discusses the economic viability of adopting solar drying systems in rural and remote areas, where access to conventional energy sources is limited. The integration of thermal storage units and hybrid systems is also explored to enhance drying consistency during intermittent solar radiation. The review concludes that solar air heaters offer a cost-effective, sustainable, and environmentally friendly solution for agricultural drying, especially in developing countries. Continued innovation in material science and system design is crucial to optimize performance and encourage widespread adoption.