He Xiaoliang, Li Jie, Chen Yiqi, Niu Baojun
China Datang Corporation Xiongan Energy Co., Ltd., China.
School of Energy and Environment, Southeast University, China.
Heliyon. 2024 Sep 4;10(18):e37442. doi: 10.1016/j.heliyon.2024.e37442. eCollection 2024 Sep 30.
In the realm of ground source heat pump (GSHP) installations, the operational efficiency of borehole heat exchangers (BHEs) is heavily dependent on the complex configurations of geological formations, including soil stratification and the movement of underground water. Our research investigated the influences of ground structure characteristics on the heat transfer performance of coaxial BHEs. A coaxial borehole heat exchanger with a three-dimensional design was constructed, setting a typical geology from the Xiong'an New Region as the boundary condition. The homogenous model with equivalent physical properties overpredicted the water temperature exiting the coaxial BHE in the stratified ground with groundwater advection by 0.2 °C, while underpredicted the heat transfer rate by 10.8 % for the 24-h period; There exists an optimal inlet flow velocity to balance the heat injection and enhanced heat transfer for the optimal heat transfer rate, which was 0.4 m/s in this study; The increase of groundwater advection velocity decreased the outlet temperature by 0.5 %, enhanced the heat transfer per meter by 15.5 % and contributed to a smaller thermal influence radius during the 24-h period. This will contribute to the design of coaxial BHEs in complex geological structure.
在地源热泵（GSHP）装置领域，钻孔换热器（BHE）的运行效率在很大程度上取决于地质构造的复杂形态，包括土壤分层和地下水的流动。我们的研究调查了地层结构特征对同轴BHE传热性能的影响。构建了一个具有三维设计的同轴钻孔换热器，将雄安新区的典型地质作为边界条件。具有等效物理性质的均匀模型对存在地下水平流的分层地层中同轴BHE出口水温的预测高估了0.2°C，而在24小时内对传热速率的预测低估了10.8%；存在一个最佳入口流速，以平衡热量注入并增强传热以实现最佳传热速率，本研究中该流速为0.4米/秒；在24小时内，地下水平流速度的增加使出口温度降低了0.5%，每米的传热增强了15.5%，并导致热影响半径更小。这将有助于复杂地质结构中同轴BHE的设计。
