Design of buried depth for vertical ground heat exchangers based on the energy efficiency degree

Based on the heat transfer characteristics of ground heat exchangers (GHEs), puts forward the concept of energy efficiency degree. Establishes the three-dimensional heat transfer model of vertical GHEs and simulates the energy efficiency degree distribution with different buried depths. Reveals migrating properties of the zonal energy efficiency degree, divides the heat transfer region of GHEs into the ineffective region and the effective region along the buried depth, and recommends some design methods of GHEs on the basis of the heat transfer energy efficiency degree.