Medium Rock-Soil Temperature Distribution Characteristics at Different Time Scales and New Layout Forms in the Application of Medium-Deep Borehole Heat Exchangers
Medium-deep borehole heat exchangers (MBHEs) have received increasing attention with respect to building heating. To avoid the thermal interference of adjacent MBHEs, the temperature distribution characteristics of medium-deep rock soil were investigated in this work. The evolution of the maximum ro...
| Main Authors: | , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2023-10-01
|
| Series: | Energies |
| Subjects: | |
| Online Access: | https://www.mdpi.com/1996-1073/16/19/6970 |
| _version_ | 1797575902965530624 |
|---|---|
| author | Jun Liu Yuping Zhang Zeyuan Wang Cong Zhou Boyang Liu Fenghao Wang |
| author_facet | Jun Liu Yuping Zhang Zeyuan Wang Cong Zhou Boyang Liu Fenghao Wang |
| author_sort | Jun Liu |
| collection | DOAJ |
| description | Medium-deep borehole heat exchangers (MBHEs) have received increasing attention with respect to building heating. To avoid the thermal interference of adjacent MBHEs, the temperature distribution characteristics of medium-deep rock soil were investigated in this work. The evolution of the maximum rock-soil thermal affected radius (MTAR) over a full lifecycle was analyzed. The results showed that the rock-soil thermal affected area (RTAA) continuously expanded in both the radial and vertical directions when the MBHE continuously extracted geothermal energy during a heating season. The factors of the thermal extraction load, fluid velocity, geothermal gradient, and pipe length, impacted the RTAA in the vertical direction, while rock-soil thermal conductivity affected the RTAA in both the radial and vertical directions. Furthermore, the thermal affected radius (TAR) in deeper formations was larger, reaching even 96 m, such that thermal interference between adjacent MBHEs was more likely to occur. The MTAR in shallow formations was limited to 20 m. Consequently, a new layout form, achieved by inclining the borehole, was proposed to increase the distance between adjacent MBHEs in deep formations. The recommended incline angle was equal to or larger than four times the TAR angle. This work provides a scientific reference for promoting the application of multiple MBHE arrays. |
| first_indexed | 2024-03-10T21:45:54Z |
| format | Article |
| id | doaj.art-9d2afab6d3304e37a27efc8c3eff128b |
| institution | Directory Open Access Journal |
| issn | 1996-1073 |
| language | English |
| last_indexed | 2024-03-10T21:45:54Z |
| publishDate | 2023-10-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Energies |
| spelling | doaj.art-9d2afab6d3304e37a27efc8c3eff128b2023-11-19T14:21:25ZengMDPI AGEnergies1996-10732023-10-011619697010.3390/en16196970Medium Rock-Soil Temperature Distribution Characteristics at Different Time Scales and New Layout Forms in the Application of Medium-Deep Borehole Heat ExchangersJun Liu0Yuping Zhang1Zeyuan Wang2Cong Zhou3Boyang Liu4Fenghao Wang5Key Laboratory of Coal Resources Exploration and Comprehensive Utilization, Ministry of Natural Resources, Shaanxi Coal Geology Group Co., Ltd., Xi’an 710026, ChinaKey Laboratory of Coal Resources Exploration and Comprehensive Utilization, Ministry of Natural Resources, Shaanxi Coal Geology Group Co., Ltd., Xi’an 710026, ChinaSchool of Human Settlements and Civil Engineering, Xi’an Jiaotong University, Xi’an 710049, ChinaShaanxi Zhongmei New Energy Co., Ltd., Xi’an 710054, ChinaShaanxi Zhongmei New Energy Co., Ltd., Xi’an 710054, ChinaSchool of Human Settlements and Civil Engineering, Xi’an Jiaotong University, Xi’an 710049, ChinaMedium-deep borehole heat exchangers (MBHEs) have received increasing attention with respect to building heating. To avoid the thermal interference of adjacent MBHEs, the temperature distribution characteristics of medium-deep rock soil were investigated in this work. The evolution of the maximum rock-soil thermal affected radius (MTAR) over a full lifecycle was analyzed. The results showed that the rock-soil thermal affected area (RTAA) continuously expanded in both the radial and vertical directions when the MBHE continuously extracted geothermal energy during a heating season. The factors of the thermal extraction load, fluid velocity, geothermal gradient, and pipe length, impacted the RTAA in the vertical direction, while rock-soil thermal conductivity affected the RTAA in both the radial and vertical directions. Furthermore, the thermal affected radius (TAR) in deeper formations was larger, reaching even 96 m, such that thermal interference between adjacent MBHEs was more likely to occur. The MTAR in shallow formations was limited to 20 m. Consequently, a new layout form, achieved by inclining the borehole, was proposed to increase the distance between adjacent MBHEs in deep formations. The recommended incline angle was equal to or larger than four times the TAR angle. This work provides a scientific reference for promoting the application of multiple MBHE arrays.https://www.mdpi.com/1996-1073/16/19/6970medium deepheat transfergeothermal heatingthermal interferencelife cycle |
| spellingShingle | Jun Liu Yuping Zhang Zeyuan Wang Cong Zhou Boyang Liu Fenghao Wang Medium Rock-Soil Temperature Distribution Characteristics at Different Time Scales and New Layout Forms in the Application of Medium-Deep Borehole Heat Exchangers Energies medium deep heat transfer geothermal heating thermal interference life cycle |
| title | Medium Rock-Soil Temperature Distribution Characteristics at Different Time Scales and New Layout Forms in the Application of Medium-Deep Borehole Heat Exchangers |
| title_full | Medium Rock-Soil Temperature Distribution Characteristics at Different Time Scales and New Layout Forms in the Application of Medium-Deep Borehole Heat Exchangers |
| title_fullStr | Medium Rock-Soil Temperature Distribution Characteristics at Different Time Scales and New Layout Forms in the Application of Medium-Deep Borehole Heat Exchangers |
| title_full_unstemmed | Medium Rock-Soil Temperature Distribution Characteristics at Different Time Scales and New Layout Forms in the Application of Medium-Deep Borehole Heat Exchangers |
| title_short | Medium Rock-Soil Temperature Distribution Characteristics at Different Time Scales and New Layout Forms in the Application of Medium-Deep Borehole Heat Exchangers |
| title_sort | medium rock soil temperature distribution characteristics at different time scales and new layout forms in the application of medium deep borehole heat exchangers |
| topic | medium deep heat transfer geothermal heating thermal interference life cycle |
| url | https://www.mdpi.com/1996-1073/16/19/6970 |
| work_keys_str_mv | AT junliu mediumrocksoiltemperaturedistributioncharacteristicsatdifferenttimescalesandnewlayoutformsintheapplicationofmediumdeepboreholeheatexchangers AT yupingzhang mediumrocksoiltemperaturedistributioncharacteristicsatdifferenttimescalesandnewlayoutformsintheapplicationofmediumdeepboreholeheatexchangers AT zeyuanwang mediumrocksoiltemperaturedistributioncharacteristicsatdifferenttimescalesandnewlayoutformsintheapplicationofmediumdeepboreholeheatexchangers AT congzhou mediumrocksoiltemperaturedistributioncharacteristicsatdifferenttimescalesandnewlayoutformsintheapplicationofmediumdeepboreholeheatexchangers AT boyangliu mediumrocksoiltemperaturedistributioncharacteristicsatdifferenttimescalesandnewlayoutformsintheapplicationofmediumdeepboreholeheatexchangers AT fenghaowang mediumrocksoiltemperaturedistributioncharacteristicsatdifferenttimescalesandnewlayoutformsintheapplicationofmediumdeepboreholeheatexchangers |