Fig 1.
Different types of HGHEs.
Table 1.
Simulation parameters.
Fig 2.
Retention curve of soil (a shows the low suction sector; and b shows the high suction section) [21].
Table 2.
Hydraulic characteristic parameter of the soil.
Fig 3.
The energy-storage soil.
Fig 4.
Meshing diagram.
Fig 5.
Comparison between the simulated outlet water temperature and the outlet water temperature from literature for verification.
Table 3.
Simulation and verification parameters.
Fig 6.
The X-Y section.
Fig 7.
Temperature field in the final cooling stage: (a) linear HGHEs; (b) spiral-coil HGHEs; (c) slinky-coil HGHEs.
Fig 8.
Nodes in the working fluid output end of different HGHE types.
Fig 9.
The changes in nodal temperature in the output end of HGHEs.
Fig 10.
Comparison of heat transfer capacities of HGHEs.
Fig 11.
Comparison of heat transfer per heat-affected area.
Fig 12.
Outlet temperature of working fluid of HGHEs.
Fig 13.
Outlet temperature of ground heat exchangers in the cooling stage.
Fig 14.
Surplus temperature of energy-storage soils.