Numerical modelling of geothermal vertical heat exchangers for the short time analysis using the state model size reduction technique

Abstract

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Simulation and experimental analysis of optimal buried depth of the vertical U-tube ground heat exchanger for a ground-coupled heat pump system

“…Esen et al [9] developed a two-dimensional Finite Element Model (FEM) to simulate the temperature distribution of the soil surrounding the GHEs of GCHPs in both cooling and heating operation modes. Kim et al [10] introduced a state model size reduction technique to reduce the required time for numerical simulation of GHEs. In another study, a new cumulative constant heat flux (CCHF) model for simulating the behavior of the GHE, was developed by Li [11] and Bouhacina et al [12].…”

“…5.The measurement of the soil temperature adopts the thermocouple temperature sensors and the computer records data through the data acquisition instrument. In order to monitor the variation of soil temperature near the GHE at different depth, a total number of 36 thermocouple temperature sensors were set in 3 boreholes measuring the annual soil temperature at 5 m,10 m,15 m, 20 m, 30 m, 40 m, 50 m, 60 m, 70 m, 80 m, 90 m and 100 m underground for each borehole. For data reliability, the average value of the 3 measured temperatures at the same depth is calculated as the final result.…”

A computationally efficient pseudo-3D model for the numerical analysis of borehole heat exchangers

“…Instead of using the Robin boundary condition, Christodoulides et al [22] used a source/sink term in the governing equation to account for the heat transfer between the fluid and the tube, assuming the heat transfer within the tube body was instantaneous because the thickness of the tube was extremely thin. An interesting modeling approach was proposed by Kim et al [23], who applied a Model Order Reduction (MOR) technique to develop a computationally efficient model for the numerical analysis of a vertical borehole heat exchanger. Kim et al [23] combined a vertical slice model with a Finite Element discretization of horizontal cross sections and validated it against analytical solutions.…”

“…An interesting modeling approach was proposed by Kim et al [23], who applied a Model Order Reduction (MOR) technique to develop a computationally efficient model for the numerical analysis of a vertical borehole heat exchanger. Kim et al [23] combined a vertical slice model with a Finite Element discretization of horizontal cross sections and validated it against analytical solutions. The authors reported a computational time reduction of 95% compared to a fully 3D model.…”

Coupling short-term (B2G model) and long-term (g-function) models for ground source heat exchanger simulation in TRNSYS. Application in a real installation

“…Finally, the finite elements model (FEM) is one of the most detailed models currently available [18,19,20,21,22,23]. This model uses a very fine discretization of the BHE, which produces the most accurate results, although having a very high computational cost.…”