Effect of baffle number on thermal and hydraulic performance of a helical solar air heater

• Optimized baffle enhanced thermal efficiency while maintaining acceptable pressure losses. • Numerical simulations showed strong agreement with experimental data. • Thermal efficiency reached 60% at 0.025 kg/s with 17–25 baffles. • The study demonstrates the strong solar energy potential of Gabes. This study aims to identify the optimal number of baffles in a Solar Air Heater (SAH) to achieve the best thermal performance with minimal pressure losses. Therefore, experimental evaluations were conducted under the environmental conditions of the Gabès region. In parallel, a CFD model was developed to simulate heat transfer and airflow within the system. Eight configurations, ranging from 0 to 25 baffles, were tested to determine the most effective design. The model was validated against experimental data, showing an average deviation of 5.27%. The results indicate that outlet air temperatures exceed 74°C for configurations with 17, 21, and 25 baffles. Furthermore, thermal efficiency increases with the number of baffles, exceeding 60% for these same configurations: It represents a 34% improvement over the smooth-duct system. Thus, the maximum pressure loss of 2615.4 Pa is recorded for the 25-baffle configuration, while it remains below 1257.7 Pa for the 17-baffle configuration at higher flow rates. Consequently, the 17-baffle configuration emerges as the optimal design, effectively balancing thermal efficiency and pressure losses. Furthermore, these results provide guidance for designing solar air heaters with balanced thermal and hydraulic performance.