Optimization of thermal efficiency in double pass solar air heating systems with emphasis on collector design parameters and operating conditions

• Maximum thermal efficiency achieved by optimizing wire mesh pitch and collector inclination. • Collector inclination angles and airflow significantly influence solar heater performance. • Clear identification of optimal operational parameters for peak thermal efficiency (60 %−80 %). • Validates solar air heaters as sustainable solutions with considerable energy savings. • Novel integrated analysis of collector parameters enhancing system design and efficiency. In this study, the thermal performance of a solar air heater system was experimentally investigated under various conditions to maximize its efficiency and effectiveness in utilizing solar energy for heating purposes. The experiments involved altering the collector's inclination angle, the wire mesh's pitch, and the mass flow rates. A comparative analysis assessed temperature rise, collector efficiency, and daily efficiency changes. The key findings indicate that the system reached its maximum heat at 10 AM across all configurations, ranging from approximately 30 °C to 70 °C. The collector efficiency peaked, primarily influenced by the solar energy received during the testing period. Similarly, daily efficiency, chiefly determined by the energy input tilt, attained maximum values between 60 % and 80 % at 10 AM. Notably, lower wire mesh pitches and higher collector inclination angles consistently led to higher thermal efficiencies, highlighting the importance of optimizing these parameters for increased energy output. This study experimentally investigates a two-pass solar air heater with wire mesh inserts in Tamil Nadu, India. Key parameters like collector inclination (15–30°), wire mesh pitch, and airflow rates (0.02–0.05 kg/s) were examined. Results showed peak thermal performance around 10:00 am, with efficiencies reaching 30–60 %. Findings offer insights for optimizing solar air heater design and enhancing renewable energy utilization. The novelty of this research lies in its comprehensive evaluation of multiple interacting variables, providing an integrated analysis that offers new insights into the optimal design and operation of solar air heating systems. These findings demonstrate that solar air heating systems are a viable alternative to traditional heating methods, delivering significant budgetary savings and enhancing the environmental image of businesses and projects. Stakeholders can utilize the results to optimize the design and operation of solar air heating systems for optimal performance, thereby promoting the adoption and effectiveness of solar energy solutions in heating applications.