Numerical Investigation of Spiral Solar Air Collectors with Various Flow Duct Designs

Pressure losses are a common issue in solar collector systems. In this study, two spiral-shaped solar collectors are analyzed to reduce the pressure losses: Collector with a rectangular flow duct, and the other with a semicircular duct. A numerical model is created using ANSYS FLUENT to study fluid flow and heat transfer in both collectors. The Discrete Ordinates radiation model and the k-ω SST turbulence model are used to analyze heat transfer and turbulent flow. The numerical model is validated with experimental results, showing an average error of 5.5%. Subsequently, the effects of different operating conditions on pressure losses and air temperature in both collectors are presented and discussed. The results show that the air temperature produced ranges from 78.6°C to 54°C as the mass flow rate increases from 0.0077 to 0.03 kg/<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$s$</tex>. The maximum pressure loss reaches 1047 Pa in the collector with a rectangular duct at a mass flow rate of 0.03 kg/<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$s$</tex>. A decrease of 167 Pa in pressure loss is found in the collector with a semicircular duct. Finally, the semicircular design shows a greater pressure loss reduction under different operating conditions.