Research Of Groundwater Seepage On Underground Pipe Group Layout Influence

As an important part of the soil-source heat pump system,buried pipe heat exchanger plays a key role in the efficiency of the heat pump.The currently existing in the study of soil source heat pump considering the soil rare studies migration is an important factor,ignoring the influence of the groundwater seepage in the soil,and in the coastal cities or the area of groundwater resources are very rich underground exist a large amount of groundwater.With the flow of groundwater,soil temperature had obvious deviation.Groundwater can reduce caused by long-term heat absorption and heat exchanger system of soil cold heat accumulation,and the heat transfer performance of ground heat exchanger has a great influence.Therefore,in order to provide theoretical basis for buried pipe system design and simulation of reference,this paper further studies the groundwater seepage on the heat exchanger model tube well layout.The influence of heat and mass transfer theory in porous media and penetration model,establishing the pure solid and the porous medium model of earth thermal transfer,analysising of groundwater seepage in a different direction and velocity under the action of seepage effect of heat transfer tube wells and nest of tubes.Using Gambit software modeling,meshing and Fluent software boundary conditions to solve the calculation process.According to the parameters of a project in Shanghai,the soil source heat pump in summer and winter run-time simulation analysis,and analyzed by simulating cloud model and different form different spacing model of buried tube heat exchange effect.According to the difference between the pure solid and porous medium soil,simulation that groundwater flow can relieve heat pump operation caused by cold heat accumulation for a long time,reducing the interference between the tube well.It is helpful for the soil to recover its initial temperature,and the heat transfer of buried pipe with seepage is much greater than that without seepage.Under the condition of no seepage soil,the heat transfer effect of drainage is more complete by comparing the form of drainage and cross drainage.At the same time,the heat accumulation and cooling capacity in the center of the pipe group are more serious,which is not conducive to the long-term operation of the heat pump.Under the seepage condition,the difference between the center of the pipe group and the surrounding buried pipe group becomes the difference between the upstream,middle and downstream of the seepage direction.Therefore,when the laying area of the pipe group is not taken into account,the downstream pipe group is superior to the fork-row model,and the heat transfer is greater.And two forms of seepage direction,there is an optimal heat transfer effect is best,making the nest of tubes area in heat,the biggest fork row form nest of tubes best seepage Angle of 30°,in-line form nest of tubes best seepage Angle 45°.Analyze the distribution of soil when the groundwater flow rate is 5e-07m/s,le-06m/s and 3e-06m/s,when the local seepage velocity is large,the heat and cooling capacity are transferred faster along the seepage direction,and the upstream pipe well has a greater impact on the downstream pipe well,resulting in a larger heat exchange gap between the upper,middle and downstream pipe Wells per unit depth,and a smaller impact between pipe Wells in the vertical seepage direction.When the local seepage velocity is small,the heat cooling capacity is transferred slowly along the seepage direction,which has a great influence on the pipe wells in the vertical seepage direction.At this time,increasing the distance between pipe wells can alleviate the heat cooling capacity accumulation in the heat pump running for a long time.Besides,in order to reduce the cold-heat interference between pipe wells and increase the heat transfer in buried pipe wells,the number of pipe wells and the spacing can be appropriately reduced and increased in the direction of seepage,so as to reduce the influence of upper interference on the middle and downstream pipe wells.In order to reduce the number of pipe wells in the seepage direction,the number of buried pipes and the spacing between pipe wells should be appropriately increased in the vertical seepage direction,so as to make full use of the flow of groundwater and reasonably arrange pipe groups to achieve the optimization purpose of minimum coverage area and maximum heat transfer of buried pipes.