Performance Evaluation of Solar Flat Plate Collector with and Without Pebble as Absorber: Case Study for Semiarid Climate Conditions

This study investigates the intricate thermal dynamics of a solar flat plate collector (FPSC) augmented with black-colored pebbles as a thermal optimizer. The impact of these pebbles on glass cover and absorber plate temperatures under different flow rate was examined. The investigation analyzed three cases with different flow rates: Case 1 (0.015 kg/s), Case 2 (0.025 kg/s), and Case 3 (0.030 kg/s), and compared performance with standard FPSC system. The system’s temperature variation and heat absorption efficiency were analyzed over several days in May and June 2023. The result shows that at flow rate of 0.015 kg/s, the water outlet temperature ranges from 27.1 to 33.6 °C, with an average value of 31.2 °C. Increasing the flow rate to 0.025 kg/s resulted in a higher water outlet temperature, with average value 35.7 °C. Further increase in flow rate to 0.030 kg/s reduces average outlet water temperature to 34.4 °C due to shorter residence time for heat absorption. The maximum thermal efficiency of FPSC system was achieved at an optimum flowrate in Case 2, reaching 58.5%, respectively. The FPSC system with pebbles shows promising results both in terms of heat absorption and thermal performance at moderate flow rates, making it a promising design configuration.