Refining the design approach for GeoExchange system

在阿尔伯塔，新建筑也越来越多地使用GeoExchange系统，该系统使用浅地面-大多数小于150米-作为空间冷却和加热的能源储存器。在该系统中，埋管换热器（BHE）是最关键的一个，因为GeoExchange系统的效率主要取决于BHE与周围地面之间的热相互作用。目前，BHE的设计方法是使用拉普拉斯变换下的热传导控制方程的解析解。然而，这些模型没有考虑地下水流对BHE热性能的影响。这种影响是有益的，因为地下水的平流有助于地面热量的消散，因此在冷却和加热模式下对BHE的性能提供了协同效应。因此，BHE的设计长度可以缩短，并且可以显著降低钻孔和安装成本。为此，我们建议Revolve Engineering Inc.和阿尔伯塔大学进行有限元法（FEM）建模的BHE结合地下水生态模拟。因此，对BHE的复杂热行为将有更明确的理解，当前的分析设计方法将针对GeoExchange进行改进，从而实现更经济可行的设计。由于GeoExchange系统在加拿大越来越受欢迎，这项研究的成果可以直接用于其他全国性项目。

In Alberta, new buildings have also been increasingly utilizing the GeoExchange system, which uses theshallow ground-mostly less than 150 meter-as an energy reservoir for space cooling and heating. In the system,the borehole heat exchanger (BHE) is the most crucial one because the efficiency of the GeoExchange systemrelies primarily on the thermal interactions between BHE and its surrounding ground. Currently, the designapproach of BHE is to use analytical solutions of heat conduction governing equations under the Laplacetransform. However, these models do not consider the impact of groundwater flow on the thermal performanceof BHE. This impact is beneficial because the advection of groundwater helps the dissipation of heat in theground and therefore provides a synergistic effect on the performance of BHE under both cooling and heatingmodes. Consequently, this design length of BHE can be shortened, and the drilling and installation costs can bereduced substantially. To this end, we propose research collaboration between Revolve Engineering Inc. andthe University of Alberta to conduct finite element method (FEM) modeling of the BHE by incorporating theco-simulation of groundwater. As a result, a more explicit understanding will be achieved on the complexthermal behavior of BHE, and the current analytical design approach will be refined for the GeoExchangesystem, leading to more economically feasible design. Since the GeoExchange system is increasingly popularacross Canada, the outcome of this research can be directly used in other nationwide projects.