Analysis of Thermal Response Test for Borehole Heat Exchangers of Ground Source Heat Pump System

The paper aims to measure a reliable ground thermal conductivity to provide a basic parameter for proper designs of borehole heat exchangers.Taking a Ground Source Heat Pump(GSHP)project which is constructed in a hilly region of Shenyang suburbs as an example,based on the principle of soil thermal responses,the research sets up an in-situ testing method for the ground thermal conductivity,and reviews the theory behind the thermal response test.Moreover,it analyses and calculates the test data using the line-source model.The results show that this hilly region has a better heat capacity,and the ground thermal conductivity of the two pilot boreholes are 2.12 W/(m · K)and 2.33 W/(m · K).Compared with the recommend values of similar rock-soil,test results indicate that the test values are reliable.The ground thermal conductivity is a prerequisite for correct designs of borehole heat exchangers.The in-situ thermal response test can obtain a reliable ground thermal conductivity.The average ground thermal conductivity of the test site is 2.23 W/(m · K).Based on the thermal response test for borehole heat exchangers of GSHP in the hilly region,this research provides a reference for similar practices.