Numerical Simulation And Experimental Study About The Soil Temperature Field Of Vertical Ground Heat Exchanger

The ground-source heat pump technology is a kind of energy-savingair-conditioning technology, using shallow geothermal energy for building heating andcooling. The ground source heat pump system is divided into water and soil source heatpump system. Unlimited by groundwater source, the soil heat pump is of energy-saving,high-efficiency, environmental protection, and got great attention of domestic andforeign experts as well as promotion from the government.Whether the design of buried tube heat exchanger of ground-source heat pumpreasonable, directly affects EER and warranty of heat pump system. The performance ofheat exchanger is closely related to the thermal conductivity and temperaturedistribution of soil. Therefore, problems still existing in practice of heat pump caused bythe complexity of underground soil, insufficient accrate basic data of buried tube heatexchanger and undeveloped construction technology. This paper studied on theproperties of the sing-U buried tube heat exchanger and the regulation of its surroundingtemperature distribution, through numerical simulation and many experiments, to getfurther research on the quality of buried rube heat exchanger. The significantachievements are as following: (a) On the assumption that the soil is of isotropy anduniform porous medium, the theory established 3-d layered model, which is for the flowand heat transfer of soil-source heat pump U-tube heat exchangger under the regulationof soil-source heat pump. (b) This paper made a simulation analysis on flow velocity andtemperature of inlet and backfill material, which shows that heat transfer quatityincreases with the growing entry speed, thermal conductivity of backfill material andrising entrance temperature of heat transfer. Besides, it also has additional imitatinganalysis on different soil water content and soil temperature field of different depth ofburied tube. The experiment indicates that the heavier the soil water content is and theshallower the buried depth is, the larger the heat transfer influence of soil temperaturefield surrounding the buried tube got, namely the heat exchanger has a wilder hot effect.(c) Setting up the buried tube heat exchanger test-bed on the foundation of theory, thispaper made a research for the heat transfer quantity of heat exchanger and the regulationof its surrounding soil temperature distribution. Either in summer or winter, the researchresult is same that soil temperature field is bound up with the heat transfer----heattransfer influences wilder range, under the condition of higher water content and the heatquantity of buried tube heat exchanger. Comparing experiment and simulation result, this theory got an indication that buried tube heat exchanger has a fixed heat transfercircle; however, hot effect radius of heat transfer in experiment is greater than insimulation calculation.