Finite element modeling of borehole heat exchanger systems

Diersch, Hans‐Jörg G.; Bauer, Dan; Heidemann, W.; Rühaak, W.; Schätzl, P.

doi:10.1016/j.cageo.2010.08.003

Cited by 163 publications

(85 citation statements)

References 7 publications

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“…Additionally, the more advanced simplified models, for example, those shown in refs. [9,10] or [12], are recommended.…”

Section: Comparison Between Measured and Simulated Resultsmentioning

confidence: 99%

“…A numerical solution using a finite element method was first proposed by Al-Khoury et al [6,7]. The method was later improved by modification of the thermal resistance network and the introduction of thermal resistance and capacity models [8]; the method has been implemented in finite element code [9,10]. The method allows the calculation of transient heat transfer in single and double U-tubes and two coaxial types of BHE.…”

Section: Introductionmentioning

confidence: 99%

“…The HTiP approach combines the advantages of other numerical methods identified in the literature analysis, because the heat transfer inside the heat exchanger pipes is simplified to one dimension, similar to refs. [6][7][8][9][10][11][12][13], which reduces the number of finite elements needed, therefore reducing the calculation speed. However, only the pipes of the BHE are reduced to 1D, and the grout is kept as a 3D object in the same way as in refs.…”

Section: Introductionmentioning

confidence: 99%

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In Situ Experiment and Numerical Model Validation of a Borehole Heat Exchanger in Shallow Hard Crystalline Rock

et al. 2018

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Accurate and fast numerical modelling of the borehole heat exchanger (BHE) is required for simulation of long-term thermal energy storage in rocks using boreholes. The goal of this study was to conduct an in situ experiment to validate the proposed numerical modelling approach. In the experiment, hot water was circulated for 21 days through a single U-tube BHE installed in an underground research tunnel located at a shallow depth in crystalline rock. The results of the simulations using the proposed model were validated against the measurements. The numerical model simulated the BHE's behaviour accurately and compared well with two other modelling approaches from the literature. The model is capable of replicating the complex geometrical arrangement of the BHE and is considered to be more appropriate for simulations of BHE systems with complex geometries. The results of the sensitivity analysis of the proposed model have shown that low thermal conductivity, high density, and high heat capacity of rock are essential for maximising the storage efficiency of a borehole thermal energy storage system. Other characteristics of BHEs, such as a high thermal conductivity of the grout, a large radius of the pipe, and a large distance between the pipes, are also preferred for maximising efficiency.

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“…Additionally, the more advanced simplified models, for example, those shown in refs. [9,10] or [12], are recommended.…”

Section: Comparison Between Measured and Simulated Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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In Situ Experiment and Numerical Model Validation of a Borehole Heat Exchanger in Shallow Hard Crystalline Rock

et al. 2018

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“…According to Diersch et al [20], it is possible to divide thermal resistance, in the case of coaxial borehole heat exchangers, into three components:…”

Section: Interpretation Of Borehole Thermal Resistance Analogous To Wmentioning

confidence: 99%

Applying Petroleum the Pressure Buildup Well Test Procedure on Thermal Response Test—A Novel Method for Analyzing Temperature Recovery Period

2018

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Abstract:The theory of Thermal Response Testing (TRT) is a well-known part of the sizing process of the geothermal exchange system. Multiple parameters influence the accuracy of effective ground thermal conductivity measurement; like testing time, variable power, climate interferences, groundwater effect, etc. To improve the accuracy of the TRT, we introduced a procedure to additionally analyze falloff temperature decline after the power test. The method is based on a premise of analogy between TRT and petroleum well testing, since the origin of both procedures lies in the diffusivity equation with solutions for heat conduction or pressure analysis during radial flow. Applying pressure build-up test interpretation techniques to borehole heat exchanger testing, greater accuracy could be achieved since ground conductivity could be obtained from this period. Analysis was conducted on a coaxial exchanger with five different power steps, and with both direct and reverse flow regimes. Each test was set with 96 h of classical TRT, followed by 96 h of temperature decline, making for almost 2000 h of cumulative borehole testing. Results showed that the ground conductivity value could vary by as much as 25%, depending on test time, seasonal period and power fluctuations, while the thermal conductivity obtained from the falloff period provided more stable values, with only a 10% value variation.

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“…Because the Nusselt number Nu depends on the type of flow, it was defined in accordance with [22] and modified Gnielinski correlation in the following way as per eq. (7): Thermal resistance as a result of conduction within the pipe material is determined by the following equation:…”

Section: Mathematical Descriptionmentioning

confidence: 99%

Coefficient of Performance Stabilisation in Ground Source Heat Pump Systems

Wołoszyn¹,

Gołaś²

2017

J. sustain. dev. energy water environ. syst.

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The number of installations with ground source heat pumps is steadily increasing. As they involve high investment costs, they require deliberate action and analysis. Research on the influence of design, materials and operating parameters on their coefficient of performance becomes of great importance. In this article the authors propose a new ground source heat pump system with horizontal ground heat exchanger and subsurface irrigation system. In order to examine the possibility of applying the system, the influence of soil moisture content on the heat pump coefficient of performance was investigated in this research. Conducting research on the real object is extremely expensive, so it was decided to conduct simulation studies using the finite element method. The presented results of research confirm that the soil moisture content has the greatest impact on the heat pump system coefficient of performance. The developed ground source heat pump system with subsurface irrigation system allow to reduce the length of ground heat exchanger loop.

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Finite element modeling of borehole heat exchanger systems

Cited by 163 publications

References 7 publications

In Situ Experiment and Numerical Model Validation of a Borehole Heat Exchanger in Shallow Hard Crystalline Rock

In Situ Experiment and Numerical Model Validation of a Borehole Heat Exchanger in Shallow Hard Crystalline Rock

Applying Petroleum the Pressure Buildup Well Test Procedure on Thermal Response Test—A Novel Method for Analyzing Temperature Recovery Period

Coefficient of Performance Stabilisation in Ground Source Heat Pump Systems

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