Feasibility Analysis Of Standing Column Well Groundwater Source Heat Pump System Applied In Self Provided Well

For all countries in the world,energy is very important for economic development.New energy has become the most important alternative energy in the 21 st century because of its clean and pollution-free characteristics.Since the middle route of the South-to-North Water Transfer Project was opened,a large number of self provided wells in Beijing,Tianjin and Hebei have been sealed up,limiting the exploitation of groundwater,which is a waste of new energy for the geothermal energy contained in them.The standing column well groundwater source heat pump system can use heat pump technology to retrofit the existing self provided wells and reuse them to heat or refrigerate buildings.It has the advantages of small initial investment,low energy consumption and good recharge.Based on the geological data of the heat source well located in Langfang,this paper establishes a two-dimensional profile model to explore the groundwater flow characteristics and the factors affecting the groundwater flow of a standing column well groundwater source heat pump system.I also establishes a three-dimensional groundwater flow model and a heat transfer model,discuss the feasibility of the application of the standing column well underground heat transfer system at the heat source well,self-provided well conditions and aquifer properties suitable for installation of single well circulation system.The conclusions are as follows::(1)It is very necessary to install single well circulating underground heat exchange system on the basis of existing underground water wells to reform the well structure.Adding baffles in the wellbore can not only eliminate the interference of low temperature return water on the pumping temperature,but also increase the influence radius of pumping water.Under the condition of mature technology and reasonable budget,the in-well waterproof device should be increased as far as possible.(2)When the permeability of aquifer is poor,the heat extraction radius is larger and the existence of weak permeable aquifer is the best.However,the sufficient aquifer water storage must be ensure,if the upper aquifer can not be recharged in time while pumping,the heat extraction performance of standing column well system will also be affected.(3)The application of standing column well underground heat exchange system in heat source wells in Langfang has a good simulation effect,the water level does not drop significantly,and the pumping temperature remains stable during the simulation period.According to the hydrogeological condition of the heat source well,the self provided wells suitable for installing standing column well underground heat exchange system should have the following conditions: self provided well can provide high temperature groundwater;the location of the wells has thicker stratum coverage to ensure the stability of the aquifer temperature in the thermal reservoir section;the permeability coefficient of the aquifer around the upper backwater area is larger,which is conducive to the recharge of groundwater and avoiding the occurrence of adverse geological phenomena such as land subsidence;the small permeability coefficient of aquifer around the lower pumping area are conducive to the extension of the heat transfer process between recharge water and aquifer.