Study on Heat Transfer Calculation Method of Ground Heat Exchangers Based on Heat Pump Unit Operation Characteristics

For ground source heat pump (GSHP) system, the dynamic heat rejected to or extracted from the ground is an important parameter to analyze the heat transfer performance of ground heat exchanger (GHE). Coupled with dynamic indoor load and actual operation characteristics of heat pump unit, a method to calculate actual dynamic heat load input of GHEs was introduced and a calculation program was developed. In an actual GSHP system project, the dynamic heat load input of GHEs was calculated and used as a boundary condition, a three-dimensional heat transfer model of this GHE field was established, and then the water temperature variation of GHEs was obtained. The actual water temperature variation of GHEs was tested and it was similar to the theoretical calculation results, thus the method was validated and could be applied in the actual engineering projects.