Etude d'un échangeur géothermique (Refroidissement par évaporation)

Abstract

This study presents an experimental investigation of the thermal performance of a copper coil heat exchanger buried in moist soil. The main objective is to evaluate the influence of soil moisture content and water flow rate on heat transfer and to improve the cooling process through evaporative cooling. The experimental setup consists of a copper coil buried at a depth of 30 cm in a container filled with moist soil. Hot water at approximately 50°C circulates through the coil at three different flow rates (8, 16, and 18 ml/s). The inlet and outlet water temperatures, soil and ambient temperatures, as well as soil moisture, were measured every 30 minutes over a total experimental period of three hours. The results showed that the flow rate of 8 ml/s provided the best cooling performance due to the longer residence time of the water inside the coil, whereas the flow rate of 18 ml/s enabled the transfer of the highest amount of thermal energy. The system performance gradually decreased over time because of the reduction in soil moisture and the weakening of the evaporative cooling effect. These findings demonstrate that a heat exchanger buried in moist soil represents a simple and cost-effective solution for enhancing heat transfer in shallow geothermal applications.