A review on thermal response test of ground-coupled heat pump systems

With the attractive advantages of high efficiency and environmental friendliness, the ground-coupled heat pump system (GCHPs) has been widely applied in various buildings around the world in recent years, and the knowledge of underground thermal properties is a prerequisite for correct design of GCHPs. As an effective way to obtain thermal properties, thermal response test (TRT) has become a routine tool for the design of larger plants with ground heat exchangers (GHEs). This paper summarizes the specifications for in situ TRT, including test setup, minimum duration, heat input rate etc., analyzes the mathematical models currently available for GHE in TRT, and compares the parameter identification methods which are necessary to obtain reasonable properties according to in situ TRT data. In addition, this paper discusses and summarizes the shortages and imperfects of the current research on TRT and gives some recommendations for future work.