In the current design of borehole heat exchangers (BHEs), the ground is commonly considered to be homogenous. However, in a layered subsurface, thermal performance of BHE can deviate drastically with different strata. Thereby, analysis of the heat transfer of a BHE with different geological...

Thermal efficiency of borehole heat exchangers (BHE) is of crucial importance for the design and optimization of ground source heat pump (GSHP) system. This paper investigates thermal efficiency of a BHE with three drillhole diameters: 121 mm, 165 mm and 180 mm. The BHE was installed in a GSHP...