Optimizing Solar Flat Plate Collector Performance with Pebbles as Thermal Mass in Arid Climate Conditions

This work investigated the performance of a solar flat plate collector (FPSC) with a natural black pebble as a sensible heat storage added to improve its thermal performance. Specifically, the effects on the temperatures of the absorber plate and glass cover are examined at two different flow rates (0.015 kg/s and 0.030 kg/s), and the results are compared to a standard flat plate collector without pebbles. Pebble's integration reduces temperature peaks, highlighting the significant effect of thermal mass of pebbles. At flowrate 0.015kg/s, the longer time spent by the fluid enhances convective heat transfer, leading to a notable 10% improvement in immediate heat transfer efficiency. While immediate efficiency decreases at higher flow rate 0.030kg/s, the sustained thermal release from the pebbles compensates for the lower peak temperatures. Particularly, the FPSC with pebbles integration shows an average maximum thermal efficiency 42.3% in flowrate that is 0.015 kg/s and while the conventional flat plate collector without pebbles was 33%. These findings highlight the complex interaction between flow rate, convective heat transfer, and thermal mass, offering valuable insights for optimizing solar flat plate collectors in water heating systems. The study suggests directions for future research, emphasizing the importance of refining collector design and exploring further modifications to enhance practical efficiency and real-world application.