Analysis And Simulation Of Ground Thermal Response Test Based On Constant Heat-temperature Method And Constant Heat-flux Method

From the point of energy utilization and environmental conservation, thetechnology of ground source heat pump had been known as the best potentialair-conditioning technique. And the ground heat physical properties had greatinfluence on the designation of ground source heat pump. At present, the groundthermal response test based on constant heat flux was used to confirm the groundthermal physical properties. However, it had some disadvantages, for example, thedata handling process is more complex and the result of parameters had greatdeviation for the influence of test condition and so on. And the ground response testbased on constant heat temperature was recently put forward in china, which cansimulate the heat extracting operation condition in winter and heat rejectionoperation condition in summer. It can directly obtain the heat extracting or rejectioncapacity of the grond buried pipe through measuring the outlet temperature ofground buried pipe, and has the advantages that the test results were visual and thedesign result can be check out. Based on that, in this paper, the thermal response testbased on constant heat flux and constant heat temperature in the Shijiazhuang,hebei province were carried out in which the ground thermal response teatinstrument was applied and the numerical method was used to analysis the responsetest results. And then the heat exchange amount of buried pipe was discussed so as toprovide practical reference and basis for the choices of more reasonable test project.The main content of the research embraces:(1) For the ground source heat pump project in Shijiazhuang, the groundthermal response test was carried out with the improved thermal response testinstrument. The test scheme、test equipment、 the parameters of borehole as well asthe measuring method of ground initial temperature and arrangement of the measurepoint were expounded；(2) The results of ground thermal response test based on two different kind ofmethod were analysis. For the ground thermal response test based on constant heat flux method, the theory of line heat source and clinder heat source was adopted todetermine the ground thermal conductivity and thermal resistance of buried pipe, andthe influence of different heat flow density and models on the results of groundthermal response test were analysis. For the ground thermal response test based onconstant heat temperature method, the heat exchange amount and mean transfercoefficient were obtained. The comparison between the ground thermal responsetests based on constant heat flux method and constant heat temperature method fromthe test equipment and measuring results was made；(3) The ground source heat pump simulate system with vertical buried pipebased on the buried pipe model in TRNSYS software were set up. Taken the officialbuilding in Shijiazhuang as example, the annual dynamic load of building wassimulated in DEST. Based on the annual dynamic load, the temperature variation ofground and the inlet and outlet of buried pipe for the long running were simulatedand the influence of each factor on the heat exchange amount of buried pipe wasanalysis.