热导率测试在四种不同的垂直钻孔结构上完成，每个孔深250英尺（76.2米），直径3/4英寸。（1.91厘米）SDR11聚乙烯（PE）管和U形管。通过在两天的时间内为每个垂直钻孔配置向3 gpm（0.1893 L/s）的水中添加监测的热量来进行测试。通过监测进出回路的水温，利用钻孔直径和回填材料的影响来确定地源热泵（GCHP）回路换热器的尺寸。48小时后，钻孔的平均温度如下:6.5英寸。（16.51厘米）直径，含标准膨润土灌浆，96.7华氏度（35.94摄氏度）；6.5英寸。（16.51厘米）直径，含细砂，82.2华氏度（27.89摄氏度）； 4.75英寸。（12.07厘米）直径，含标准膨润土，91.6华氏度（33.11摄氏度）；4.75英寸。（12.07厘米）直径，含热改良膨润土灌浆，86.2华氏度（30.11摄氏度）。根据获得的温度数据确定土壤的热导率和扩散率后，使用商用GCHP软件包确定所需的垂直回路长度。设计该垂直回路的设施的峰值冷负荷为160吨（563千瓦）。地面区域仅支持144个钻孔，间距为17英尺（5.18米）。钻孔直径、回填材料、管道类型和原始地面材料都会影响垂直回路长度。在本项目中，使用标准膨润土回填代替砂土，将环路长度增加了49%。 这相当于钻孔增加13680英尺（4170米）。通过使用沙子或热改良膨润土灌浆代替标准膨润土灌浆，可以缩短GCHP环场的长度。单位:双引文:研讨会，ASHRAE交易，1998年，第104卷，pt。1A，旧金山

Thermal conductivity testing was completed on four different vertical bore hole configurations, each 250 ft (76.2 m) deep with 3/4 in. (1.91 cm) SDR11 polyethylene (PE) pipe and U-tubes. The testing was conducted by adding a monitored amount of heat to 3 gpm (0.1893 L/s) of water over a two-day period for each vertical bore hole configuration. By monitoring the water temperature entering and exiting the loop, the effects of bore hole diameter and backfill material were used to size a ground-coupled heat pump (GCHP) loop heat exchanger. The bore holes had the following average temperatures after 48 hours: 6.5 in. (16.51 cm) diameter with standard bentonite grout, 96.7°F (35.94°C); 6.5 in. (16.51 cm) diameter with fine sand, 82.2°F (27.89°C); 4.75 in. (12.07 cm) diameter with standard bentonite, 91.6°F (33.11°C); 4.75 in. (12.07 cm) diameter with thermally improved bentonite grout, 86.2°F (30.11°C). After determining the thermal conductivity and diffusivity of the soil from the temperature data obtained, a commercially available GCHP software package was used to determine the required vertical loop length. The facility for which this vertical loop was designed, had a peak cooling load of 160 tons (563 kW). The ground area would only support 144 bore holes spaced 17 ft (5.18 m) apart. The bore hole diameter, backfill material, type of pipe, and virgin ground material all affect vertical loop length. For this project, using standard bentonite backfill instead of sand increased the loop length 49%. This equates to 13,680 ft (4170 m) more bore hole. The length of a GCHP loop field can be reduced by using sand or thermally improved bentonite grout instead of standard bentonite grout.Units: Dual