Effects of varying heat transfer rates for borehole heat exchangers in layered subsurface with groundwater flow

• DOI: 10.1016/j.applthermaleng.2024.123007
• Publication Date: 2024-03-20T22:24:24Z
• Authors: Y. Guo; J. Zhao; W.V. Liu

The existence of groundwater flow adds a convective heat component to shallow geothermal pump systems, significantly improving transfer efficiency. Numerous analytical and numerical methods have been proposed assess the impact on ground exchangers. However, simulations often require significant resources time, while conventional solutions overlook time depth-varying rates, leading inaccurate temperature predictions. This study proposes computationally efficient semi-analytical solution by extending line source coupling it with thermal resistance model. approach addresses variations in rate over depth, overcoming limitations solutions. Compared three-dimensional model constructed COMSOL Multiphysics, average absolute percentage error (MAPE) borehole wall temperatures for U-shaped exchanger (BHE) is approximately 1 %, across wide range water velocities conductivity ratios between two contacting geological layers. A advantage its computational can complete long-term 9,000 steps about 10 min, as opposed models that typically several hours. excellent efficiency substantial accuracy make simple effective tool design optimization BHEs engineering applications.