Zhang Rui
Shandong Institute of Petroleum and Chemical Technology, Donging, Shandong, China.
PLoS One. 2025 Mar 11;20(3):e0319430. doi: 10.1371/journal.pone.0319430. eCollection 2025.
The heat transfer performance of a ground heat exchanger (GHE) directly influences the operational performance of a ground source heat pump (GSHP) system. The fluid temperature within the GHE is constrained by the protective temperature limits of the GSHP unit. Specifically, the inlet water temperature has an upper limit in summer and a lower limit in winter. These temperature limits further affect the heat exchange efficiency between the GHE and the surrounding soil. In this study, an experimental station featuring a single U-shaped GSHP system was constructed, and a three-dimensional model of the system was developed. Experiments were conducted by operating one or two GHEs to investigate the heat transfer per unit well depth and the matching relationship between cooling capacity and indoor load when the inlet water temperature of the heat pump unit approaches its summer and winter limits. In summer, when operating a single GHE, the heat transfer per unit well depth reached 134.4 W/m at an inlet temperature of 45 °C. When the cooling supply just matched the cooling load demand, the heat transfer per unit well depth was 131.5 W/m. However, prolonged operation led to a scenario where the cooling supply could no longer meet the load demand. In winter, operating a single GHE resulted in a heat transfer per unit well depth of 43.95 W/m at an inlet temperature of 5 °C. These results indicate that when the number of heat exchangers is insufficient, the inlet water temperature of the heat pump unit may reach or exceed the limit value, leading to decreased unit efficiency. Additionally, inadequate heat exchange between the GHE and the soil results in insufficient cooling or heating capacity, failing to meet the indoor load requirements.
地埋管换热器（GHE）的传热性能直接影响地源热泵（GSHP）系统的运行性能。地埋管换热器内的流体温度受地源热泵机组的保护温度限制。具体而言，进水温度在夏季有上限，在冬季有下限。这些温度限制进一步影响地埋管换热器与周围土壤之间的热交换效率。在本研究中，构建了一个具有单个U形地源热泵系统的实验站，并建立了该系统的三维模型。通过运行一个或两个地埋管换热器进行实验，以研究热泵机组进水温度接近其夏季和冬季限值时单位井深的传热情况以及制冷量与室内负荷之间的匹配关系。在夏季，运行单个地埋管换热器时，进水温度为45℃时单位井深的传热达到134.4W/m。当供冷量刚好与冷负荷需求匹配时，单位井深的传热为131.5W/m。然而，长时间运行导致供冷量无法再满足负荷需求的情况。在冬季，运行单个地埋管换热器时，进水温度为5℃时单位井深的传热为43.95W/m。这些结果表明，当地埋管换热器数量不足时，热泵机组的进水温度可能达到或超过限值，导致机组效率降低。此外，地埋管换热器与土壤之间的热交换不足导致制冷或制热量不足，无法满足室内负荷要求。
