Thermal performance of aquifer thermal energy storage system in different geological structures

Geothermal energy has received widespread attention as a resource-rich, sustainable, and environmentally friendly clean energy source. As a promising solution for geothermal energy development, aquifer thermal energy storage (ATES) technology has become a research focus. In-depth exploration of the application mechanisms, influencing factors, and optimization strategies of aquifer storage systems is crucial for improving storage effectiveness and promoting the widespread application of this technology. This paper establishes a three-dimensional numerical model of aquifer thermal energy storage systems and validates it using experimental data to study the effects of porosity, underground seepage velocity, load size, and reinjection temperature on storage characteristics. Results show that while higher porosity can accelerate heat transfer and expand storage range, it also increases heat loss; the optimal porosity for storage effectiveness is 0.4. Underground seepage direction significantly affects storage efficiency, with seepage opposing the pumping direction mitigating thermal breakthrough and improving storage performance. Under balanced winter-summer load conditions, larger heating and cooling loads and appropriate reinjection temperatures help improve storage efficiency, with reinjection temperatures of 28 °C/2 °C showing superior performance in both seasons. The study reveals key factors affecting underground aquifer thermal energy storage system performance, providing a theoretical basis for subsequent optimization.