Research On Calculation Method Of Heat Transfer In Shallow Soil-air Heat Exchange System

General Secretary Xi Jinping announced at the 75 th United Nations General Assembly that China will strive to reach the peak of carbon dioxide emissions by 2030 and strive to achieve carbon neutrality by 2060.This is an important symbol of China’s new journey of vigorously building an ecological civilization and a beautiful China.And the latest initiatives.Building energy consumption accounts for about one-third of global energy consumption,and building energy consumption has a huge impact on the ecological environment.To this end,countries are vigorously developing new clean energy technologies to reduce carbon emissions.The soil-air heat exchanger system uses the temperature difference between the soil and the air in winter and summer to pre-treat the air,and then sends the treated air into the air source heat pump.The coefficient of performance of the air source heat pump is improved,and energy consumption is reduced.This paper uses ANSYS WORKBENCH to establish a three-dimensional unsteady-state numerical model of the soil-air heat exchanger,and analyzes the influencing factors and energy-saving effects of the buried heat exchanger when the system operates in the Qinhuangdao area.The outdoor air is preheated in winter and the outdoor air is cooled in summer.The air after the heat exchange through the buried pipe enters the air source heat pump,and the COP of the air source heat pump system linked to the soil-air heat exchanger is greatly improved.Through ANSYS WORKBENCH,the main influencing factors of the heat transfer performance of the system are simulated and calculated: the air temperature difference between the inlet and outlet of the heat exchanger pipe increases first and then decreases with the increase of pipe diameter,and increases with the increase of pipe length,buried depth,and pipe spacing,And decrease with the increase of pipeline inlet flow.After the system completes the winter operating conditions and passes the spring transition season,the soil temperature is slightly lower than the initial temperature.After the summer operating conditions are completed and the autumn transition season,the soil temperature is slightly higher than the initial temperature.It can be considered that the soil temperature field after the system runs for one cycle Return to the initial level.Based on the above research,the soil-air heat exchanger linkage air source heat pump system and the traditional air source heat pump are compared and analyzed in terms of economics.The results show that the soil-air heat exchanger linkage air source heat pump system has obvious economic advantages.Which shows that the above system has theoretical research value and good application prospects.