Numerical Simulation And Analysis On Heat Transferring Performance Of Double T-tube Ground Heat Exchanger

With the new era of " Lucid waters and lush mountains are invaluable assets." concept gradually gaining popularity,the characteristics of ground-source heat pump air-conditioning systems with environmental protection,energy conservation and other characteristics have also received increasing attention.The ground source heat pump air conditioning system is a system device that uses the underground geothermal energy resources and the ground source heat pump to convert the energy to achieve the purpose of building space air conditioning.The most important part of the ground source heat pump air conditioning system is the ground tube heat exchanger.Therefore,the study of the geothermal heat exchanger has become the primary research topic of the ground source heat pump air conditioning system.First,combined with the climate of Wuhan region temperature thermal physical characteristics,geological structure and soil,analyzed the underground vertical buried heat exchanger heat transfer principle,established a vertical double u-shaped ground tube heat transfer model,and provided using ANSYS CFX software to numerical simulation of summer conditions,it is concluded that buried pipe and the surrounding soil temperature field distribution and temperature field with the change of time,vertical double u-shaped ground pipe import and export of the distribution of temperature field around lag phenomenon.Secondly,by establishing the vertical double U-shaped ground-tube heat transfer model with different parameters,the changes in “unit heat transfer capacity” and “unit-well heat transfer total” under different parameters are obtained,affecting the heat exchangers.The various factors of heat transfer were analyzed to study the influence of various factors on the heat transfer performance of the vertical double U-shaped ground heat exchanger.The results show that the lengths of the buried pipe,the spacing between the branches,the thermal properties of the pipe,the inlet temperature,the inlet flow rate,and the thermal conductivity of the soil have different degrees of influence on the heat transfer performance of the vertical double U-tube heat exchanger.Various factors are taken into consideration to determine the design parameters.Finally,by establishing a vertical double U-shaped ground-tube heat transfer model in an ideal state,the “thermal short-circuit loss coefficient” under different parameters is obtained.The influence degree and influence rule of soil thermal conductivity on thermal short-circuit phenomena are explained,and the main reasons for this rule are explained in detail,so as to find a method for optimizing ground-tube heat transfer,and finally provide certain guidance for engineering practice.