| Shenyang City is a good city for the promotion and application of groundwater source heat pumps in China.However,due to the influence of hydrogeological conditions on the pumping and recharge efficiency of groundwater source heat pump projects,it has been restricted in promotion and application.In recent years,with the urban construction and underground space development and utilization,especially the subway project has changed the original groundwater environment,resulting in the operational energy efficiency of the nearby groundwater source heat pump project will also be affected to varying degrees.Therefore,it is necessary to explore the influence of subway engineering on aquifer seepage and heat conduction and the impact of subway engineering on nearby water source heat pump engineering.Taking the proposed groundwater source heat pump project in Liaoning Building near Metro Line Ⅱ as an example,through the analysis of the impact of the subway project on the groundwater source heat pump,the reliability of the groundwater source heat pump in field area was evaluated,and the optimal control scheme for the water source heat pump project was proposed.Provide technical basis for the planning and design of groundwater source heat pump project of field area.The specific research contents are as follows:(1)Analysis of hydrogeological conditions in the study area.Through the study of hydrogeological conditions,the distribution characteristics of aquifers and recharge layers,groundwater depth and groundwater quality and water temperature in the study area were analyzed.It is understood that the holocene alluvial-diluvial gravel and the upper pleistocene alluvial-diluvial gravel in the study area contain a small amount of clay as the main aquifer and recharge layer.The groundwater level is buried at 11.0～12.0m,and the groundwater temperature is 11.0～12.0℃,indicating the study area is in a suitable area for groundwater source heat pumps.(2)Indoor simulation test of the influence of subway engineering on aquifer seepage and thermal conductivity is studied.Through the on-site pumping test and recharge test in Liaoning Building,the pumping water permeability coefficient is 45.95m/d,the impact radius is 122.13m,the recirculation permeability coefficient is 4.99m/d,and the influence radius is 283.53m.The indoor sandbox simulates the impact test of the subway project on the groundwater temperature,and the influence of the subway project on the water level of the reflow well in different locations.According to the test results,the heat transfer cylinder wall heat conduction formula is used to obtain the water source heat pump pumping well.The distance should be 120m from the subway.In addition,using Darcy’s law to obtain the feasibility range of the recharge well outside the subway 72m,thus determining the scope of the subway project’s impact on the water source heat pump.(3)Reliability analysis of groundwater source heat pump project in Liaoning Building is studied.According to the load required by the groundwater source heat pump project of Liaoning Building,the water demand during the cooling period and the heating period are calculated separately.The number of pumping and recharge wells in the groundwater source heat pump project is determined by calculating the single well pumping amount and recharge amount from the hydrogeological parameters measured on site.The reliability evaluation index system of the well site with hydrogeology,energy quality and environmental characteristics were constructed,and the dynamic weight function method was used for evaluation.The evaluation results showed that under the constraints of design conditions such as the spacing of the wells in the field,the 15 recharge well could not be satisfied.The layout requirements of the layout of the Liaoning Building are unreliable.Therefore,it is necessary to propose a water source heat pump regulation scheme to ensure the user’s water demand.(4)Numerical simulation and prediction of groundwater level and water temperature in the groundwater source heat pump regulation scheme of Liaoning Building were studied.Considering multiple energy sources to assist energy supply,the system structure and operation mode of two groundwater source heat pump control schemes are proposed,and the water source heat pump drainage scheme is determined.By establishing a numerical simulation model of the coupling of groundwater flow and water temperature,the simulation predicts the change trend of groundwater level and water temperature in different schemes.The results show that the highest water level in the two well plans during the simulation period is 34.9 m,which does not exceed the ground elevation.The surrounding temperature of the pumping well is 9.5～11.9℃,which can meet the requirements of 5K heat exchange in winter and 7K heat transfer in summer.The minimum temperature of the recharge well is 5.8℃,and the maximum temperature is 16.7℃,both greater than 5℃ and less than 19℃.Therefore,both solutions meet the design requirements from a technical perspective.(5)Optimized selection of the regulation scheme for the water source heat pump project of Liaoning Building was studied.Through the establishment of construction and operation cost as the evaluation index of the control plan,the information entropy method is used to obtain the evaluation value of the information entropy weight of each program to optimize the control plan of the groundwater source heat pump project of Liaoning Building.The final selection plan is scheme 1 as the optimal design of the groundwater source heat pump project.In summary,this paper studies the optimal operation mode of groundwater source heat pump in Liaoning Building.In order to avoid the impact of subway project on the water pumping of groundwater source heat pump,two water source heat pump control schemes are proposed and selected.On the basis of solving the actual engineering problems,it provides a scientific basis for the application and design of the water source heat pump under the influence of the subway project. |
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