A study was conducted to investigate heat transfer in a ground heat exchanger (GHE) system with a novel capric acid-lauric acid eutectics/expanded graphite (EG) composite PCM. The composite PCM was prepared and analyzed. The optimal mass ratio of fatty acid to EG was 10:100 with a melting heat of 134.13 kJ/kg. The thermal performances of GHE system with different fraction ratios of the composite PCM mixed in the backfill material were predicted. The heat exchange amount was increased by 17.71% when the PCM fraction ratio was increased from 0% to 70%. However, the average temperature in the borehole after the recovery period increased from 16.94 °C to 18.32 °C with increasing PCM ratio from 0% to 70% due to heat release during solidification. Moreover, the impacts of different running modes on the heat transfer, PCM utilization, and temperature recovery were investigated. The most rapid reduction of heat exchange amount over time was observed under the on/off ratio of 12:12 and at the PCM ratio of 70%. In addition, the average temperature in the borehole increased by 1.5 °C-2.7 °C with increasing on/off ratio from 8:16 to 12:12 in all the cases with PCM. Heat exchange amount in the running mode of 4 h interval after every 4 h operation was at least 10.3% higher than that in the mode of 12 h interval after every 12 h operation. By contrast, the temperature and phase recovery significantly deteriorated in the 4 h intermittent mode in the cases with PCM backfilling.

进行了一项研究，以研究具有新型癸酸-月桂酸低共熔/膨胀石墨（EG）复合PCM的地面热交换器（GHE）系统中的传热。制备并分析了复合PCM。脂肪酸与EG的最佳质量比为10：100，熔融热为134.13 kJ / kg。预测了不同比例的复合PCM混合在回填材料中的GHE系统的热性能。当PCM比率从0％增加到70％时，热交换量增加了17.71％。但是，由于凝固过程中的热量释放，恢复期后井眼中的平均温度从16.94°C增加到18.32°C，PCM比从0％增加到70％。此外，不同运行模式对传热，PCM利用率，和温度恢复进行了研究。在开/关比为12:12且PCM比为70％的情况下，观察到了随着时间的推移热交换量的最快减少。此外，在所有使用PCM的情况下，井眼中的平均温度都随着开/关比从8:16增加到12:12而增加了1.5°C-2.7°C。每隔4h运转后4h间隔运行模式下的热交换量比每隔12h运转后12h间隔模式下的热交换量高至少10.3％。相反，在使用PCM回填的情况下，在4 h间歇模式下，温度和相恢复显着降低。在所有使用PCM的情况下，钻孔的平均温度都从1.5：C升高到2.7.C，开/关比从8:16增加到12:12。每隔4h运转后4h间隔运行模式下的热交换量比每隔12h运转后12h间隔模式下的热交换量高至少10.3％。相反，在使用PCM回填的情况下，在4 h间歇模式下，温度和相恢复显着降低。在所有使用PCM的情况下，钻孔的平均温度都从1.5：C升高到2.7.C，开/关比从8:16增加到12:12。每隔4h运转后4h间隔运行模式下的热交换量比每隔12h运转后12h间隔模式下的热交换量高至少10.3％。相反，在使用PCM回填的情况下，在4 h间歇模式下，温度和相恢复显着降低。