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Medium Rock-Soil Temperature Distribution Characteristics in Different Time Scales and New-Type Well Layout Form in Application of Medium-Deep Borehole Heat Exchanger
Liu, J.; Zhang, Y.; Wang, Z.; Zhou, C.; Liu, B.; Wang, F. Medium Rock-Soil Temperature Distribution Characteristics at Different Time Scales and New Layout Forms in the Application of Medium-Deep Borehole Heat Exchangers. Energies2023, 16, 6970.
Liu, J.; Zhang, Y.; Wang, Z.; Zhou, C.; Liu, B.; Wang, F. Medium Rock-Soil Temperature Distribution Characteristics at Different Time Scales and New Layout Forms in the Application of Medium-Deep Borehole Heat Exchangers. Energies 2023, 16, 6970.
Liu, J.; Zhang, Y.; Wang, Z.; Zhou, C.; Liu, B.; Wang, F. Medium Rock-Soil Temperature Distribution Characteristics at Different Time Scales and New Layout Forms in the Application of Medium-Deep Borehole Heat Exchangers. Energies2023, 16, 6970.
Liu, J.; Zhang, Y.; Wang, Z.; Zhou, C.; Liu, B.; Wang, F. Medium Rock-Soil Temperature Distribution Characteristics at Different Time Scales and New Layout Forms in the Application of Medium-Deep Borehole Heat Exchangers. Energies 2023, 16, 6970.
Abstract
Medium-deep Borehole Heat exchanger (MBHE) has been widely paid attention for building heating. In order to avoid the thermal interference of adjacent MBHEs, temperature distribution characteristics of medium-deep rock-soil was investigated in this work. The evolution on maximum rock-soil thermal affected radius (MTAR) in full life cycle was further analyzed. The results showed that the rock-soil thermal affected area (RTAA) continuously expands in both radial and vertical directions during a heating season. Several factors of thermal extraction load, fluid velocity, geothermal gradient and pipe length have main impacts on the RTAA in vertical direction. Rock-soil thermal conductivity affects the RTAA in both radial and vertical directions. In non-heating season, temperature difference of rock-soil in radial direction dominates the temperature recovery in the first year while geothermal flow nearly dominates temperature recovery after 20 years. The thermal affected radius (TAR) in the 30 th year could be determined as an effective MTAR in full life cycle. In order to decrease installed distance of adjacent MBHEs, a new well layout form by deflecting borehole was proposed. The recommended deflection angle is equal to or larger than 4 times TAR angle. This work provides scientific reference for promoting application of multiple MBHE arrays.
Keywords
Medium-deep; Heat transfer; Geothermal heating; Thermal interference; Life cycle
Subject
Engineering, Energy and Fuel Technology
Copyright:
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
