dc.description.abstract | Heat is one of tracers that can reflect groundwater flow and heat transport. Using temperature as a natural tracer, compared with chemical tracer, reduces negative impacts on the environment. In order to improve the accuracy of estimating the water flow and temperature transfer behavior in aquifers, this study employs experimental approaches and HYDRUS-2D numerical model to analyze the water temperature, water flow and heat transport. Laboratory experiments are also considered in this study to get sandbox material parameters that include hydraulic conductivity, van Genuchten parameter, thermal conductivity and volumetric heat capacity. The sandbox was placed at a constant temperature environment, which is 155 cm in length, 2 cm in width, and 55 cm in height. There are tanks on both left and right sides of the sandbox to control the water level. The hot water was injected into the sandbox by a single point with constant injection rate for 5 hours, and the dynamic process of heat transport was measured during the experiment. Experiments show that the temperature of the lower half of the sandbox is more significantly affected by hot water. The closer to the water injection point, the faster the temperature rise and the shorter the time to reach the temperature peak. After the water injection is stopped, the temperature drops quickly, and it drops to room temperature the fastest. The numerical simulation result of Case 1 can roughly simulate the water injection situation of the sand box, and the simulation and test results of Case 2 have large errors. When the model is used to test the influence of injection temperature and injection flow rate on the heat transfer distance, when the injected water temperature is close to the ambient temperature, the heat transfer distance increases as the temperature increases. As the water injection temperature increases, the increase in distance decreases. It means that a certain degree of temperature rise will help increase the transmission distance, but the effect of temperature rise is limited, and the benefits will
gradually decrease. | en_US |