The subsurface near the vertical borehole heat exchanger (BHE) contains different geological layers and thermal properties that are variable with depth. The stratified subsurface

variable thermal properties

and groundwater flow would make the heat transfer of BHE more complex. Thus

the traditional homogenous model inevitably leads to some problems for the design of BHE in a layered subsurface. In this study

through a borehole field test in Nanjing

a numerical model considering five strata was developed and verified. Comparing the numerical multilayered model with the traditional homogenous FLS and MFLS models shows that the outlet temperature of the numerical model is 0.5 °C lower than the FLS model after 60 d of heating and 0.3 °C higher than the MFLS model. This also indicates that the temperature response is different at different layers. Furthermore

the axial temperature profiles of different layers at different distances under different heating times are presented and explored.