Refining the design approach for GeoExchange system

在艾伯塔省，新的建筑也越来越多地使用地球交换系统，该系统使用浅地层--大多不到150米--作为空间制冷和供暖的储能库。在该系统中，井式换热器是最关键的换热器，因为地热交换系统的效率主要依赖于井式换热器与周围地面之间的热相互作用。目前，BHE的设计方法是利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动对BHE热工性能的影响。这一影响是有益的，因为地下水的平流有助于地下热量的消散，因此在冷却和供热模式下对BHE的性能提供了协同效应。因此，可以缩短井底钻具的设计长度，大大降低钻井和安装成本。为此，我们建议Revolve Engineering Inc.和艾伯塔大学开展研究合作，通过结合地下水的生态模拟来对BHE进行有限元建模。因此，将对北京热电厂的复杂热行为有更明确的了解，并将改进现有的地热交换系统的解析设计方法，从而实现更经济可行的设计。由于地理交换系统在加拿大各地越来越受欢迎，这项研究的成果可以直接用于其他全国性的项目。

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.