Analysis of the effect of the cross-section of spiral fins in pipes of a linear focusing solar collector on heat transfer efficiency and hydrodynamic properties

In this paper, a numerical study of the operation of a linear focusing solar collector equipped with internal spiral axial fins, which have three different cross-sectional shapes, is carried out. These fins perform a dual function: they act as vortex generators and contribute to turbulence of the flow, improving the heat exchange process. The main purpose of the study was to determine the influence of the geometric characteristics of spiral fins on the thermal efficiency and hydrodynamic parameters of the system. The simulation was performed using the control volume method (FVM) in the Ansys Fluent software environment version 2024. The equations of conservation of mass, momentum, and energy, as well as the equations for the kinetic energy of turbulence, were used for the numerical solution. The SIMPLE algorithm was used to ensure consistency between speeds and pressure. The studies were carried out with a Reynolds number of 5000, which made it possible to consider the features of flow turbulence and its effect on heat transfer and hydraulic losses. Three different cross-sectional shapes of spiral ribs were considered. The numerical results included temperature distributions along the pipe, heat transfer rates, and hydraulic resistance values for each configuration. The data obtained made it possible to conduct a comparative analysis of the influence of various geometric parameters of the edges on the characteristics of the system. This approach provides a deeper understanding of the mechanisms of heat and mass transfer in pipes with internal spiral structures, which is important for further optimization of solar collector designs.