U-Turn Shape Effect on Effective Thermal Conductivity of Double Pass Photovoltaic Thermal (PVT) Systems Configuration

This study explores the thermal performance of double-pass photovoltaic thermal (PVT) systems by investigating the influence of turn shape on heat transfer characteristics using computational fluid dynamics (CFD) simulations. The aim is to evaluate various turn shapes, including half-circle, triangle, half-hexagon, half-octagon, and box, to determine their impact on turbulent intensity, effective thermal conductivity, and outlet temperature in PVT systems. The investigation reveals significant variations in heat transfer efficiency among the different turn shapes, with the triangle-shaped turn demonstrating superior performance across multiple parameters. The findings highlight that the triangle-shaped turn exhibits enhanced turbulence generation and heat exchange efficiency compared to other shapes. Specifically, the triangle-shaped turn achieves a maximum turbulent intensity of approximately 70%, surpassing other shapes which achieve around 60%. Moreover, the triangle-shaped turn displays a longer and more substantial area of high heat exchange, resulting in an effective thermal conductivity improvement of up to 20% compared to alternative shapes. Furthermore, the analysis indicates that the triangle-shaped turn exhibits a faster increase in outlet temperature, reaching steady-state conditions within 15 seconds, while other shapes require up to 19 seconds. These results underscore the significance of turn shape in optimizing the thermal efficiency of PVT systems.