| Title |
Development of a Three-Dimensional Numerical Model of the Vertical Ground-Coupled Heat Exchanger Considering the Effects of the Thermal Capacity |
| DOI |
http://dx.doi.org/10.6110/KJACR.2016.28.7.293 |
| Keywords |
수직형 지중열교환기 ; 지열원 히트펌프 ; 열용량 ; 3차원 수치모델 Vertical ground heat exchangers ; Ground-coupled heat pump ; Thermal capacity ; Three-dimensional numerical model |
| Abstract |
A three-dimensional (3D) numerical model of the vertical ground-coupled heat exchanger is useful for analyzing the modern ground source heat pump system. Furthermore, a detailed description of the inner side of the exchanger allows to account for the effects of the thermal capacity. Thus, both methods are included in the proposed numerical model. For the ground portion, a FDM (Finite Difference Method) scheme has been applied using the Cartesian coordinate system. Cylindrical grids are applied for the borehole portion, and the U-tube configuration is adjusted at the grid, keeping the area and distance unchanged. Two sub-models are numerically coupled at each time-step using an iterative method for convergence. The model is validated by a reference 3D model under a continuous heat injection case. The results from a periodic heat injection input show that the proposed thermal capacity model reacts more slowly to the changes, resulting in lower borehole wall temperatures, when compared with a thermal resistance model. This implies that thermal capacity effects may be important factors for system controls. |