A Computational Fluid Dynamics Analysis on the Impacts of Different Materials, Thicknesses and Rotation Speeds on the Performance of a Parabolic Trough Solar Collector

The aim of this study is to develop a dynamic numerical model for a parabolic trough solar collector with a rotating absorber tube and to systematically investigate the combined effects of rotation speed, tube material, and wall thickness on its thermal performance. The main novelty is in the simultaneous investigation of three key design parameters—rotation speed (10 and 15 rad/s), absorber tube material (copper, brass, and nickel), and wall thickness (1.45, 1.65, and 1.85 mm)—which have not been studied collectively in previous literature. The simulations are analyzed by ANSYS. Because the non-uniform heat flux is not available in the ANSYS software, a user defined function (UDF) subroutine code for applying non-uniform heat flux is programmed. Results show that the rotation of the pipe has a major effect on the layers close to the wall, while the middle layers of the fluid are not influenced. Moreover, it is proven that as the fluid distance from the inlet increases, the rotational speed and consequently the maximum fluid velocity increase. This shows that the fluid gradually approaches its limiting velocity and that there is no significant change in the average velocity of the fluid inside the pipe as the pipe length increases. Besides, as the fluid progresses along the pipe, the rate of increase in its temperature gradually decreases and the fluid reaches a state close to a steady temperature. Finally, it is proven that among material alloys used, the copper tube has the best performance for heat penetration and creates the highest maximum temperature in the fluid.