Investigating the impact of serrated absorber plates on the efficiency of solar air heaters: A mathematical modeling study

Conventional solar air heaters often suffer from limited heat transfer efficiency due to suboptimal absorber plate designs and high irreversibility, constraining their applicability in thermal energy systems. Addressing this limitation, the present study develops and validates a comprehensive mathematical model—implemented in MATLAB—for a double-pass solar air heater equipped with a novel serrated absorber plate. The primary objective is to quantify the enhancements in both energy and exergy performance and to identify the governing design and operating parameters. The model incorporates detailed energy and exergy balance equations for all system components and shows strong agreement with previous experimental data. Parametric analysis reveals that increasing the gap between the glass cover and absorber plate results in an 11% increase in thermal efficiency and a 21% improvement in exergy efficiency. Additional findings highlight the positive influence of fin height, air mass flow rate, and solar irradiance on system performance, while acknowledging the tradeoff of increased pressure drop. Qualitatively, the serrated geometry enhances turbulence, boosts heat transfer, and lowers entropy generation relative to flat absorbers. These results have practical implications for designing cost-effective, high-performance solar air heaters suitable for drying, space heating, and renewable thermal applications, thereby contributing to sustainable energy system optimization.