Abstract
Seasonal storage of thermal energy, by pumping heated water through a borehole array in the summer, and reversing the water flow to extract heat in the winter, can ameliorate some of the intermittency of renewable energy sources. Simulation can be a valuable tool in enhancing the efficiency of such storage systems. This paper develops a simple, efficient mathematical model of spatial temperature dynamics that focuses on the radial water flow in a cylindrical borehole array. The model calculates the time course of the temperature difference between outgoing and incoming water accurately, and allows new optimization strategies to be explored easily. A strategy based on discharging water heated by the array before it reaches the array center can increase the storage capacity by 25% for a system with a 20% smaller radius than the well-studied Drake Landing system. If the density of boreholes is also doubled, the improvement is 29%.
| Original language | English |
|---|---|
| Article number | 1918 |
| Journal | Energies |
| Volume | 13 |
| Issue number | 8 |
| DOIs | |
| State | Published - Apr 1 2020 |
Keywords
- Numerical simulation
- Optimization
- Underground thermal energy storage