Geothermal Energy Storage And Transportation In Shallow Aquifer

Shallow aquifer plays a critical role in water circulation and energe circulationsystem. Transportation, storage and transformation of Water and heat in theair-soil-groundwater Joint are important in agriculture, water resource, environmentalengineering. Although the theory of coupled water and Heat transport in soil is widelyrecognized, it has been hadly applied on shallow aquifer. Quantification of theinfluence of surrounding Environment on s geothermal field remainsto be settled.Relied on the shallow ground water experimental base on the first grade terraceof Qinyi River, soil temperature and water level were dynamic observed andlong-term measured by both manual and automatic loggers; the shallow aquifertemperature was ranged between16.5and18.8during the observation. Filedand laboratory experiments were conducted to parameter recognition with Jinxianhospital heat pump system, including pumping test, seepage test, soil particle size test.According to the hydrogeological conditions of the instance, a numerical simulationmodel of coupled groundwater flow field and temperature field was established.The study indicts:1When fluctuation of air temperature is expressed by Sine curve and Fourierseries, the shallow ground water shows seasonal fluctuation subject to air temperature.The amplitude of the temperature response in shallow ground water to a change of airtemperature decreases with increasing depth and decreasing flux, both by analyticalmethod and simulation method.2Considering the rainfall, the temperature wave amplitude decaies slower andspreads deeper, but because under normal conditions, rainfall infiltration speed tooslow, without the impact of heavy rains or prolonged snowfall, the impact of rainfallon the temperature of the entire system is small.3When the heat pump systems work, the aquifer temperature severely changes.The unsaturated zone temperature will change with it, the magnitude of the changeswill be inversely proportional to depth. The impact is small in the foreseeable workperiod.4Overall, Thermal properties of the aquitard temperature act as the maininfluence parameters for conduction effect under the natural conditions. Irrigationschemes act as the major influence, when the water source heat pump system operats and geothermal field is controlled by thermal convection.5The fluctuation of shallow groundwater temperature during mining wassimulated, with model parameters corrected by measured data. The minimumtemperature in winter during exploitation in the aquifer near pump wells would be14.7, and the maximum temperature in summer would rise to23.5. Thesimulation results show that when considering the temperature change caused by thewater source heat pump system, auxiliary hot and cold source was needed in order tomeet the system.