NUMERICAL & MATHEMATICAL MODELING OF THERMAL PERFORMANCE IN SOLAR AIR HEATER WITH VARIOUS ABSORBER SHAPES

Abstract

Solar energy, a renewable resource, offers a sustainable alternative to fossil fuels for generating power and heat. Solar air heating (SAH) systems provide one of the most efficient methods for capturing solar energy and converting it into usable heat. The performance of these systems is significantly influenced by the design of the absorber plate, which plays a crucial role in capturing and transferring heat to the air passing through the system. This study investigates the thermal performance of SAHs with different absorber plate shapes, including flat plate and zigzag patterns, using mathematical modeling, CFD simulations, and experimental data. The objective is to identify the most effective absorber shapes for enhancing heat transfer and improving overall system performance. Numerical analysis was conducted using the ANSYS 2020 R2 program, with air flow set at 0.15 m/s and an inlet temperature of 30°C, under varying solar radiation intensities. The results indicate that the Zigzag Plate significantly outperforms the Flat Plate in heat transfer efficiency, Nusselt number, and thermal efficiency. Specifically, the Nusselt number for the Zigzag Plate at a Reynolds number of 14000 is approximately 90, compared to 75 for the Flat Plate. Additionally, at 900 W/m² solar irradiation, the Zigzag Plate achieved a thermal efficiency of 80%, whereas the Flat Plate reached 60%. The Zigzag Plate also showed higher absorber temperatures for instance, at 9:00 AM with 300 W/m² solar irradiation, the Flat Plate reached 47.86°C, while the Zigzag Plate reached 67.23°C.These findings suggest that Zigzag patterns significantly enhance heat absorption and convective heat transfer, especially at lower irradiance levels. The study recommends further optimization of absorber geometries, particularly Zigzag patterns, to achieve higher heat transfer rates and thermal efficiencies, making them a more efficient option for solar air heaters. The Zigzag Plate’s performance under varying solar conditions demonstrates its potential for enhancing the overall efficiency of solar heat collection systems.