Ground heat exchangers (GHE) are extensively utilized in geothermal heating and cooling systems due to their efficiency and sustainability. This research presents an experimental study on the effect of flow rate on the performance of horizontal ground heat exchangers (HGHE) in sand soil. The study investigates how varying flow rates impact heat exchange efficiency, soil temperature distribution, and thermal performance during hot climates. A laboratory setup was developed to simulate real-world conditions, incorporating a spiral coil heat exchanger buried in sand soil. Experiments were conducted at different flow rates (5 L/min, 6 L/min, and 7 L/min), while monitoring temperature variations in both the soil and circulating fluid. The results indicate that increasing the flow rate enhances convective heat transfer, leading to a 31.8% improvement in heat exchange rate (HER) when increasing from 5 L/min to 7 L/min. However, the benefits diminish over time, with HER decreasing by approximately 55% within the first three hours as thermal equilibrium is approached.
In terms of soil temperature distribution, the study found that heat dissipation in the horizontal direction becomes negligible beyond 0.4 meters, while in the vertical direction, temperature influence fades beyond 0.4 meters. At lower flow rates, soil temperature gain increased by up to 38% compared to higher flow rates, due to prolonged heat retention. This study focuses the importance of optimizing flow rates to balance energy efficiency and thermal performance in ground heat exchangers