Aquifer thermal energy storage (ATES) has been proved to be an efficient way to achieve seasonal thermal energy storage and can improve the efficiency of heat pump systems greatly. But for ATES systems using brine aquifer as thermal energy storage medium, there is large reduction in permeability of the aquifer due to the difference of salinity and temperature between the injected water and aquifer, then heat transfer process could be influenced. In present work, effects of injection salinity and injection temperature on the underground temperature and performance of the ATES system are studied. Results indicate that reducing injection salinity slows down the heat transport in the brine aquifer, and improve the thermal energy storage of the brine aquifer thermal energy storage system due to the decrease of hydraulic conductivity of brine aquifer. Decreasing injected cold water temperature or increasing injected hot water temperature is helpful to improve the thermal energy storage, which is the comprehensive influence of the reduction of hydraulic conductivity and the increase of temperature difference.
Keywords brine aquifer, injection salinity, injection temperature, underground temperature