Deep coaxial borehole heat exchangers (CBHEs) have been considered to enable cost and energy savings in building energy systems. However, achieving improved performance requires optimal design and operation of the CBHE. This work presents a case study for a building energy system in Finland, for which a hydraulic diagram was developed to incorporate a number of deep CBHEs (800 m to 2400 m) with multiple operating modes. To evaluate the techno-economic feasibility with optimized operating strategies, a four-step methodology is introduced, combining steady-state modelling, dynamic simulation and system optimization. The systems with a CBHE were found economically feasible compared to a district heating connection, enabling lower annualized total system cost (18.3–26.3%) and operating costs (49.1–53.5%). With deeper CBHEs, the main cost reductions originated from improved heat pump performance, increased operating flexibility and decreased capacity requirements of process components. However, the benefits partly decreased non-linearly with increased CBHE depth. Economic feasibility displayed the highest sensitivity to the price of electricity, with a relatively smaller impact for deeper CBHEs. Furthermore, maximizing the heat pump performance was found economically more significant than achieving a high borehole heat extraction rate.

深同轴埋管换热器 (CBHE) 已被认为可以在建筑能源系统中实现成本和能源节约。然而，要获得更好的性能，需要对 CBHE 进行优化设计和操作。这项工作介绍了芬兰建筑能源系统的案例研究，为此开发了一个水力图，以结合具有多种操作模式的多个深部 CBHE（800 m 至 2400 m）。为了评估优化运营策略的技术经济可行性，引入了一种结合稳态建模、动态仿真和系统优化的四步方法。与区域供热连接相比，具有 CBHE 的系统在经济上是可行的，能够降低年化总系统成本 (18.3–26.3%) 和运营成本 (49.1–53.5%)。有了更深的 CBHE，成本降低的主要来源是热泵性能的提高、操作灵活性的提高和工艺组件容量要求的降低。然而，随着 CBHE 深度的增加，收益部分呈非线性下降。经济可行性对电价的敏感性最高，对更深层次的 CBHE 的影响相对较小。此外，发现最大化热泵性能在经济上比实现高钻孔热提取率更重要。对更深的 CBHE 的影响相对较小。此外，发现最大化热泵性能在经济上比实现高钻孔热提取率更重要。对更深的 CBHE 的影响相对较小。此外，发现最大化热泵性能在经济上比实现高钻孔热提取率更重要。