The Study On Heat Transfer Performance Test And Simulation Of The Vertical Ground Heat Exchanger

Since the 21st century, with the increasingly scarce of earth’s traditional energy, the topic of energy become more and more attention, due to its high efficiency and energy saving, Ground Source Heat Pump is gradually recognized by people and the technology has been widely used. Underground heat exchanger is one of the most key point of ground source heat pump technology, the heat exchanger size of its heat capacity directly affects the unit’s efficiency.The properties of the U-vertical underground heat exchanger as the research object, using GAMBIT software to establish the same as the actual size of the U-vertical underground heat exchanger pipe three-dimensional model, and using the FLUENT software for winter and summer respectively to carry on the numerical simulation, under the condition of coupling method with double factors analysis of various factors on the heat transfer performance of the vertical u-vertical ground heat exchanger are studied. The results show that the import flow velocity, inlet temperature, back-filled materials coefficient of thermal conductivity, the drilling depth and soil thermal physical properties on vertical U tube heat exchanger had significant effect on the heat transfer performance, respectively analyzes the various factors on the influence law of the heat exchange performance and make a concrete analysis to the main cause of this law.Based on the simulation analysis, compared to single or double heat transfer performance of the U-vertical underground heat exchanger is found that the factors of vertical double U tube heat exchanger heat transfer performance and the influence of vertical single U tube heat exchanger heat transfer performance are basically identical. Under the same operating conditions, the double pipe heat of unit well depth and single well in heat are higher than that of single tube, but the import and export of double tube temperature difference is larger than that of single tube import and export temperature difference has decreased significantly. Short circuiting problem is common problem in a ground source heat pump system, and restrict the development of the vertical u-vertical ground heat exchanger key factors,。 In the paper,based on the simulation analysis of various factors on the single and double U tube heat exchanger short circuiting condition, the influence of different factors on the thermal effects of short circuit size.Thus all above can make contribution the basic data for engineering practice in Ground source heat pump system systems.