Experimental Study And Error Analysis Of Site Geothermal Thermal Response Test Method

Ground source heat pump technology is an effective way to utilize shallow geothermal energy.Before designing the ground source heat pump system,the geotechnical thermal response test is carried out to obtain the thermal properties of the underground rock and soil,and provide basic data for the system design.The thermal properties of underground rock and soil are mainly obtained through field test of geotechnical thermal response tester.The accuracy depends mainly on the test method and the error of the tester.Based on the large-scale buried tube heat transfer test bench,the geotechnical thermal response test method and performance of the tester were evaluated and verified.The influence of many factors on the test accuracy and its error analysis were analyzed.Enhance and expand the performance and application of large-scale buried tube heat exchange test bench.This test bench is mainly used for experiments such as heat exchange performance of buried pipes.Based on the complete test equipment and data record monitoring system owned by the experimental platform,the geothermal finite element heat transfer calculation software was used to simulate the temperature field of the buried pipe area,and compared with the experimental results,the simulation and test heating process The temperature field change of the buried pipe area provides data,conditions and methods for determining the thermal property parameters by using the inverse heat conduction problem.The ground heat transfer analysis model was selected.According to the actual heat transfer conditions of the buried pipe in the actual project,three heat transfer models of line heat source,hollow column heat source and solid column heat source were selected for numerical simulation.Through comparative analysis,combined with the parameter estimation method,a line heat source model with high precision and convenient data processing wasselected to process the experimental data.The influence of the geotechnical thermal response test method on the test results was discussed.A series of experiments were carried out on the two main test methods,the constant heat flow method and the constant temperature method.The concept of heat transfer coefficient was introduced,and the experimental results were analyzed systematically.The main influencing factors of the test errors of the two methods and their application were proposed.condition.Theoretical analysis shows that compared with the constant temperature method,the constant heat flow method is perfect in the heat transfer mechanism,and the test instrument is simple and the test time is short,which is more suitable for engineering application.The experimental research results show that the test time,the initial temperature distribution of the soil and the heat flow Density,etc.,are the main factors affecting the accuracy of the constant heat flow method.Considering the unfavorable factors such as the small thermal diffusivity of quartz sand used in the sandbox in the experiment,the experimental results are well coupled with the engineering field test results.Based on this,the measures and methods for optimizing the geothermal response test of the constant heat flow method have reference value for scientifically processing the experimental data and improving the accuracy of the geotechnical thermal response test.