Numerical and experimental study of thermal efficiency of a spiral flat plate solar collector by changing the spiral diameter, flow rate, and pipe diameter

A numerical and experimental study of a flat plate solar collector (FPSC) with a spiral pipe containing water configuration is performed. Constant flux is applied to the FPSC. Radiation losses from the FPSC and convection heat transfer around it are also considered. The finite element method is used for simulations. For better analysis, an experimental model for the FPSC is fabricated and tested. The results show that the trend of changes in FPSC average temperature, water outlet temperature, and Heat transfer coefficient are largely similar. They are enhanced with the increase of the outer diameter of the spiral and the diameter of the FPSC pipe and are reduced with flow rate. Also, the amount of pressure drop and pumping power intensifies by enhancing the flow rate and decreasing the outer diameter of the spiral and the pipe diameter. In addition, it is seen that the maximum Thermal efficiency (Th-eff) corresponds to the inner diameter of 120 mm and the outer diameter of 700 mm. For some parameter intervals, the pipe with diameters of 9.53 mm and 15.88 mm leads to the maximum amount of Th-eff.