Evaluating the performance of solar air heater-thermal solar collectors in Iraq's environment: a case study in Mosul

This study presents a rigorous experimental investigation into the thermal and hydraulic performance of three single-pass solar air heater (SAH) configurations: flat (FPSAH), 45° corrugated (CPSAH), and 45° wavy (WPSAH) absorber plates. Testing was conducted simultaneously in Mosul, Iraq, to ensure identical environmental conditions, evaluating the collectors under both natural and forced convection modes (mass flow rates up to 0.01847 kg/s). The methodology focuses on the novelty of using 45° optimized geometries as a simple yet effective modification to enhance heat transfer without the need for complex internal baffles. Performance was assessed using key metrics: outlet air temperature, temperature difference (ΔT), and net effective efficiency, which incorporates parasitic electrical losses from the fans. Results revealed that the WPSAH significantly outperformed other designs; under natural convection, it achieved a peak outlet temperature of 101.8 °C and a ΔT of 79 °C, compared to 83.7 °C and 60 °C for the FPSAH. In forced convection, the WPSAH reached a peak net daily efficiency of 70.25%, surpassing the CPSAH (60.59%) and FPSAH (50.15%). While the wavy profile incurred a 21% higher pressure drop, its enhanced thermal gain (20% higher than FPSAH) justified the hydraulic trade-off. These findings confirm the WPSAH as the optimal design for domestic space heating in semi-arid climates, providing a manufacturing-friendly solution capable of reducing household electricity consumption by over 20%.