| This paper summarizes the research status of shallow geothermal energy at homeand abroad, elaborates on the theoretical basis of geological environment impactassessment of shallow geothermal energy, makes an overview of the basic conceptsand features of shallow geothermal energy, analyzes shallow geothermal energyresources storage conditions in Beijing. The situation of development and utilizationof shallow geothermal energy and the current situation problems and trends ofdevelopment and utilization of shallow geothermal resources in Beijing are alsoanalyzed.In this paper, geological environment evaluation system on the development andutilization of shallow geothermal energy is established. After determine the evaluationand parameters, it selects the model area as a research instance, uses Surfer andthree-dimensional groundwater level trends to define the hydrogeological parametersanalyze the impact of geotemperature field.By using the Fluent software, it simulates the temperature field changes ofsingle-hole and group-hole in a cooling and heating season. It can be concluded thatthe superposition of temperature field in heat-exchange holes can only affect theiradjacent holes. The changes in the amplitude of the temperature field in winterthermal-taken conditions are smaller than that in summer heat conditions with2.4mradius of heat influence. It also carried out the research of heat influence scope, andthe radius of heat influence in single-hole is less than3m under short-term heat test,while the scope of temperature impact of the heat-exchanger hole can reach3m at thenorth-south direction in the case of continuous heat transfer in single-hole.The changes in temperature within the scope of the permafrost are examined. Theresults show that with the outdoor temperature changes, the temperature below theground of0.5m is relatively larger than ground temperature, the volatility is moreobvious, and the soil temperature has greater influence by the surface temperature. Research on the relationship between geotemperature field and groundwater flowhas been carried out. It can be seen that the underground water flow has a certainextent affect on the geotemperature field. A kind of lithology formation with goodheat transfer performance has a higher temperature corresponding value. It alsoassesses the impact of groundwater source heat pump system on the geotemperaturefield, indicates that the soil itself has good heat storage capacity and the ability toresume operation, the operation of system will not have a greater temperaturegeothermal field irreversible heat accumulation. The changes of geotemperature haveassociated with the heat power of the system, and the sound engineering system willnot cause a significant change in the geotemperature field. Limited impact ongroundwater quality and microorganisms can be concluded during the operation ofsystem.The computing model of temperature distribution in a storage river is established,and a soil-temperature field model coupled with the pipeline using ANSYS is made atthe same time, it can be drawn that the temperature influence on pipeline to the soillayer is significant within a small range. In summer conditions, the soil temperaturenear the wall of the pipe is increased significantly. The soil layers have isotherms withsimilar concentric, while it has little effect on the overall temperature distribution ofthe soil layer. The establishment of a computing model of temperature changes ofsurface water pipeline transport is made, it indicates that the temperature of pipelinemedium has smaller changes along the way, and is not more than0.3℃in thecommon range, and the performance coefficient of the heat pump has limited changesaccordingly. These conclusions provide a theoretical basis for comprehensiveevaluation of the geological impact on the shallow geothermal energy developmentand utilization. |
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