A Study Of The Characteristics Of Ground Heat Exchanger Under The Coupled Heat Conduction And Groundwater Advection Conditions

Ground Source Heat Pump (GSHP) is an environmentally friendly, energy saving and efficient air conditioning technology. It has the advantages of low noise, durable and reliable. comfortable。It can be widely used in public buildings, commercial buildings, residential apartments, hospitals, schools and other buildings. GHPS brings opportunity. for the sustainable development of our country, and even to solve the energy crisis, environmental pollution. The accuracy of the Ground heat exchanger design is crucial to ensure GSHP operate with efficient and stable, The heat study between ground heat exchanger and the surrounding soil is a matter combines HVAC and hydro-geological: for one hand, The thermal properties of soil is important for the heat exchange of ground pipe: for another, Seepage of the groundwater should not be ignore for a ground heat exchanger design, while the existing mathematical models did not consider the impact of groundwater seepage, so that the heat exchanger design is larger than actual, Increase the initial investment the heat pump system.This paper describes the research status of GSHP, summarizes the existing heat transfer mathematics model, and considers soil as porous medium, uses mathematical formulas express heat transfer process considering flow-thermal coupling. This Paper uses numerical simulation software Comsol3.5a, Established a physical model of a single U tube, carry out the Simulation of soil thermal conductivity = 1.5,3,4.5, porosity = 0.1,0.3,0.6 and different of groundwater seepage on the impact of soil temperature distribution, propose based on Pe value as the standard whether consider heat convection transfer. Establish physical model of the pipe group in different arrangement, calculate the result under certain flow condition, Analyze the different arrangement of the of pipe impact on entire group, propose the optimal arrangement and layout of the pipe group.In this paper heat exchanger test-box indoor was built on the basis of Darcy's law, 9 copper U-tubes were arranged in rectangular uniform to simulate the heat exchange between U-tube and soil. Respectively carry out the experiments in 68 hours under the influence of dry sand, saturated sand and water flow, the results indicate that under the flow condition U-tube generate temperature difference between tube in and out is 5℃, Obviously bigger than the condition dry sand which is only 1℃, and saturated sand 3℃. Also found by the experiments that under the flow conditions, upstream U-tube generated interference to downstream.