Abstract Ground Source Heat Pumps (GSHP), as a renewable source heating, ventilating, and air conditioning (HVAC) technology, has the highest energy efficiency among different heat pump types. One of the major drawbacks of GSHPs is the long-term ground temperature variations as a result of heat accumulation or depletion in the ground. This contribution puts forward a novel ground thermal recovery system for horizontal ground heat exchangers in a hot climate. The proposed recovery system consists of open-loop horizontal Ground-Air Heat Exchangers (GAHEs) that are buried between the horizontal Ground-Water Heat Exchangers (GWHEs). A fan supplies ambient air to the GAHE pipes when the soil around GWHE pipes is warmer than the ambient air, to remove the accumulated heat from the ground. A three-dimensional quasi-steady Computational Fluid Dynamics (CFD) model of the system is developed. This model is then used to evaluate the five years performance of the GSHP system with the proposed thermal recovery system for space cooling of a residential house in a hot desert climate. Moreover, the effect of various geometrical parameters, i.e., GWHE length, GWHE pipe spacing, GWHE buried depth, and GAHE pipe diameter on the system performance, are investigated. It is demonstrated that, by deploying the proposed recovery system, the five-year average annual Coefficient of Performance (COP) of the system can be increased by up to 20.2%. Moreover, applying the proposed recovery system not only enhances the ground thermal recovery but also improves the maximum cooling load that can be supplied to the building per unit land area. Furthermore, it is demonstrated that by applying the proposed recovery system, the average annual COP of the system gradually increases; however, it decreases for the GSHP without a recovery system.

中文翻译：

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炎热气候下水平地埋式换热器的新型地热回收系统

摘要 地源热泵（GSHP）作为一种可再生能源供暖、通风和空调（HVAC）技术，在不同类型的热泵中具有最高的能效。地源热泵的主要缺点之一是由于地下的热量积累或消耗而导致的长期地面温度变化。这一贡献提出了一种新型的炎热气候下水平地埋换热器地热回收系统。提议的回收系统由埋在水平地下水热交换器 (GWHE) 之间的开环水平地空气热交换器 (GAHE) 组成。当 GWHE 管道周围的土壤温度高于环境空气时，风扇会向 GAHE 管道提供环境空气，以去除地面积聚的热量。开发了系统的三维准稳态计算流体动力学 (CFD) 模型。然后，该模型用于评估 GSHP 系统的五年性能，以及提议的热回收系统，用于在炎热的沙漠气候中对住宅进行空间冷却。此外，还研究了各种几何参数，即 GWHE 长度、GWHE 管间距、GWHE 埋深和 GAHE 管径对系统性能的影响。结果表明，通过部署建议的回收系统，该系统的五年平均年度性能系数 (COP) 可提高多达 20.2%。此外，应用所提出的回收系统不仅可以增强地面热回收，还可以提高单位土地面积可以提供给建筑物的最大冷负荷。此外，结果表明，通过应用建议的回收系统，该系统的年均 COP 逐渐增加；然而，对于没有回收系统的地源热泵来说，它会减少。