本研究提出了一种新的钻孔结构，试图在以冷却为主的气候条件下减少所需的地下换热器（GHE）长度。它由一个U形管孔组成，周围环绕着一个由热增强相变材料（PCM）与沙子混合而成的环。在钻孔周围有一个设计合理的PCM环，在峰值建筑负荷期间，大量排出的热量用于熔化PCM。这会减缓热泵回流温度的升高。在热泵不运行的非高峰期，储存在环中的热能通过热传导释放到地面。在此过程中，PCM环固化，然后准备在下一个热泵运行循环中释放热量。通过利用与PCM熔融潜热相关的相对较高的能量含量，PCM环可减少所需的钻孔长度。 本文介绍了用于获得钻孔周围和PCM环内温度分布的数值模型。在以冷却为主的气候条件下，进行了几次年度模拟，以评估拟议钻孔配置的优点。初步结果表明，所提出的配置可以将钻孔长度减少多达9%。引文:美国科学与技术研究院学报第119卷第2部分，科罗拉多州丹佛市。

A new borehole configuration is proposed in this study in an attempt to reduce the required length of ground heat exchangers (GHE) in cooling-dominated climates. It consists of a single U-tube borehole surrounded by a ring made of a thermally enhanced phase change material (PCM) mixed with sand.With a properly designed PCM ring around the borehole, a significant portion of the rejected heat during peak building loads is used to melt a PCM. This slows down the increase in the return temperature to the heat pump. In nonpeak periods when the heat pump is not operating, thermal energy stored in the ring is released into the ground by heat conduction. In the process, the PCM ring solidifies and is then ready for the release of heat during the next heat pump operation cycle. By taking advantage of the relatively high energy content associated with the latent heat of fusion of PCM, the PCM ring may reduce the required borehole length. This paper presents the numerical model used to obtain the temperature distribution around the borehole and in the PCM ring. Several annual simulations were undertaken to evaluate the merits of the proposed borehole configuration in a cooling-dominated climate. Preliminary results show that the proposed configuration can reduce the borehole length by up to 9%.