Modelling thePerformanceof DoublePassSolar Air Collectors

This study presents a detailed investigation into the thermal performance of double-pass solar air collectors (DPSACs) through a combination of experimental testing and theoretical modelling. DPSACs are widely recognized for their ability to enhance heat transfer and reduce energy losses, making them suitable for applications such as drying and space heating. Experimental measurements were conducted under outdoor conditions focusing on key operational parameters such as mass flow rates (MFR) and solar radiation intensity. A theoretical model was developed and validated against experimental data, achieving high agreement with R2 values of 0.989 for outlet temperature and 0.917 for thermal efficiency. Results indicate that increasing MFRs initially improves thermal efficiency by enhancing convective heat transfer. However, higher MFRs reduce the outlet air temperature, as shorter air residence times limit the transfer of heat to the air. Solar radiation was found to have a pronounced effect at lower MFRs, emphasizing the need for optimal MFR selection to balance efficiency and temperature output. The study highlights a preferred operating range of 0.01–0.025 kg/s for maintaining efficient thermal performance under varying solar intensities. The validated model provides a robust framework for predicting the performance of DPSACs under diverse conditions.