Heat transfer analysis of U-type deep borehole heat exchangers of geothermal energy

2021 ◽  
Vol 237 ◽  
pp. 110794
Author(s):  
Wenke Zhang ◽  
Jianhua Wang ◽  
Fangfang Zhang ◽  
Wei Lu ◽  
Ping Cui ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Exchangers ◽  
Geothermal Energy ◽  
Heat Transfer Analysis ◽  
Deep Borehole ◽  
Borehole Heat Exchangers

scholarly journals Simulation Analysis on the Heat Performance of Deep Borehole Heat Exchangers in Medium-Depth Geothermal Heat Pump Systems

Energies ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 754 ◽  
Author(s):  
Jiewen Deng ◽  
Qingpeng Wei ◽  
Shi He ◽  
Mei Liang ◽  
Hui Zhang
Keyword(s):  
Heat Transfer ◽  
Heat Pump ◽  
Heat Exchangers ◽  
Geothermal Energy ◽  
Heat Transfer Performance ◽  
Deep Borehole ◽  
Geothermal Heat ◽  
Temperature Heat ◽  
Geothermal Heat Pump ◽  
Borehole Heat Exchangers

Deep borehole heat exchangers (DBHEs) extract heat from the medium-depth geothermal energy with the depth of 2–3 km and provide high-temperature heat source for the medium-depth geothermal heat pump systems (MD-GHPs). This paper focuses on the heat transfer performance of DBHEs, where field tests and simulation are conducted to analyze the heat transfer process and the influence factors. Results identify that the heat transfer performance is greatly influenced by geothermal properties of the ground, thermal properties and depth of DBHEs and operation parameters, which could be classified into external factors, internal factors and synergic adjustment. In addition, the long-term operation effects are analyzed with the simulation, results show that with inlet water temperature setting at 20 °C and flow rate setting at 6.0 kg/s, the average outlet water temperature only drops 0.99 °C and the average heat extraction drops 9.5% after 20-years operation. Therefore, it demonstrates that the medium-depth geothermal energy can serve as the high-temperature heat source for heat pump systems stably and reliably. The results from this study can be potentially used to guide the system design and optimization of DBHEs.

Comparative analysis of heat transfer performance of coaxial pipe and U-type deep borehole heat exchangers

Geothermics ◽  
2021 ◽  
Vol 96 ◽  
pp. 102220
Author(s):  
Wenke Zhang ◽  
Wenjing Li ◽  
Bjørn R Sørensen ◽  
Ping Cui ◽  
Yi Man ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Comparative Analysis ◽  
Heat Exchangers ◽  
Heat Transfer Performance ◽  
Transfer Performance ◽  
Deep Borehole ◽  
Borehole Heat Exchangers

scholarly journals Low enthalpy geothermal energy: borehole heat exchangers (BHE). Geological and geothermal supervision during active construction in support of the energy certification of buildings - ESBE certification plan

2012 ◽  
Author(s):  
Lorenzo Cadrobbi ◽  
Fioroni Daniele ◽  
Alessandro Bozzoli
Keyword(s):  
Energy Conservation ◽  
Heat Exchangers ◽  
Energy Efficient ◽  
Geothermal Energy ◽  
Energy Requirements ◽  
Effective Coverage ◽  
Correct Execution ◽  
Environmental Technologies ◽  
Borehole Heat Exchangers ◽  
Ongoing Monitoring

This article draws on the experience matured while working with low-enthalpy geothermic installations both in the design and executive phase as well as ongoing monitoring, within the scope of energy conservation as it relates to building and construction. The goal is to illustrate the feasibility of adopting the ESBE certification protocol (Certification of Energy Efficient Low-Enthalpy Probes) aimed at optimizing the harnessing of local geothermic resources to satisfy the energy requirements of a building, measured against the initial investment. It is often the case, in fact, that during the course of a construction project for a given low-enthalpy installation, we verify incompa tibilities with the local geologic and geothermic models, which, if inadequate during construction, can compromise the proper functioning of the installation and its subsequent operation. To this end, the ESBE method, which adheres to the governing environmental regulations, and which takes its cue from technical statutes within the sector, permits us to validate via verification, simulations and tests, the geothermic field probes used in construction in an objective and standardized manner, thereby joining and supporting the most recent protocols for energy certification of buildings (LEED 2010, CASACLIMA 2011, UE 20120/31 Directive). ESBE certification operates through a dedicated Certifying Entity represented by the REET unit (Renewable Energies and Environmental Technologies) of FBK (Bruno Kessler Foundation) of Trento. The results obtained by applying the ESBE method to two concrete cases, relative to two complex geothermic systems, demonstrate how this protocol is able to guarantee, beyond the correct execution in the field of geothermic probes, an effective coverage of the energy requirements of the building during construction adopting the best optimization measures for the probes in keeping with the local geological and geothermic model.

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