DESIGN AND DEVELOPMENT OF AN AUTOMATED CONVEX LENS SOLAR ENERGY DIRECTED DRYER

Preserving farm produce after harvest is a major challenge, especially in areas where electricity supply is not reliable. Traditional open sun drying, although common, has many disadvantages such as long drying time, uneven moisture removal, and exposure to dust, insects, and rain. This project focuses on the design and development of an automated convex lens solar energy-directed dryer aimed at providing a simple, efficient, and low-cost solution for small-scale farmers. The system uses a convex lens with a focal length of 15 cm to concentrate solar energy into a drying chamber, increasing the temperature and speeding up the drying process. To improve performance, an Arduino Uno microcontroller, servo motors, and light-dependent resistors (LDRs) were used to automatically adjust the lens for better sun tracking. A mathematical model was also developed to determine the optimum tilt angle of the lens to capture maximum solar energy. The prototype, built with aluminum for portability and durability, works with natural convection and does not require fans or external collectors. Tests carried out showed that the dryer can reach about 60 °C and reduce the drying time of products like tomatoes and leafy vegetables to less than two hours, compared to much longer times with traditional sun drying. This project shows that combining solar concentration with automation can improve drying efficiency, reduce post-harvest losses, and provide a sustainable method for food preservation in rural and off-grid areas.