FIGURE 2 - uploaded by I. Vušanović
Content may be subject to copyright.
![Triangular mesh of the domain cross section and zoom of the mesh near the borehole 3. RESULTS AND DISCUSSION The developed model is validated through comparing its results with the available reference data sets from a large laboratory "sandbox" with a borehole and U-tube. This experimental installation is developed by Building and Environmental Thermal Systems Research Group at the Department of Mechanical Engineering Technology of Oklahoma State University [7]. Large wooden box has a horizontal layout, 18.3 m in length with square vertical cross section with side of 1.83 m. Borehole in the form of an aluminium pipe with an inner diameter 12.6 cm is cantered horizontally along the length of the box. U-tube made of HDPE (high density polyethylene) with the inner diameter of 27.33 mm and the outer diameter 33.40 mm is centred with spacers in the borehole which is then filled with a bentonite grout. The box is filled with sand which is saturated with water. Constant far field temperature (ground temperature away from the borehole) is simulated by circulating air of the constant temperature through the gap around sandbox and the outer surrounding box. The ends of the sand box are insulated. In the experiments, water is circulated through the U-tube and heated by means of an electric heater. Temperatures of water at the inlet and outlet of the U-tube, temperature of sand at various positions as well as the voltage and current at electric heater are recorded once every minute. Relevant parameters for the model validation are given in Table 1.](profile/I-Vusanovic/publication/289607718/figure/fig2/AS:1116470717218818@1643198770635/Triangular-mesh-of-the-domain-cross-section-and-zoom-of-the-mesh-near-the-borehole-3.png)
Triangular mesh of the domain cross section and zoom of the mesh near the borehole 3. RESULTS AND DISCUSSION The developed model is validated through comparing its results with the available reference data sets from a large laboratory "sandbox" with a borehole and U-tube. This experimental installation is developed by Building and Environmental Thermal Systems Research Group at the Department of Mechanical Engineering Technology of Oklahoma State University [7]. Large wooden box has a horizontal layout, 18.3 m in length with square vertical cross section with side of 1.83 m. Borehole in the form of an aluminium pipe with an inner diameter 12.6 cm is cantered horizontally along the length of the box. U-tube made of HDPE (high density polyethylene) with the inner diameter of 27.33 mm and the outer diameter 33.40 mm is centred with spacers in the borehole which is then filled with a bentonite grout. The box is filled with sand which is saturated with water. Constant far field temperature (ground temperature away from the borehole) is simulated by circulating air of the constant temperature through the gap around sandbox and the outer surrounding box. The ends of the sand box are insulated. In the experiments, water is circulated through the U-tube and heated by means of an electric heater. Temperatures of water at the inlet and outlet of the U-tube, temperature of sand at various positions as well as the voltage and current at electric heater are recorded once every minute. Relevant parameters for the model validation are given in Table 1.
Source publication
This paper presents a three dimensional numerical model for the simulation of heat flow in a geothermal borehole heat exchanger. Two equations of the mathematical model are simultaneously solved to arrive at the solution: energy equation for the fluid flowing in the U-bended tube and energy equation for the heat flow in the pipe, grout and surround...
Context in source publication
Context 1
... whole domain is divided in layers in vertical z direction to take into account the change of heat transfer fluid with depth. Each horizontal layer is discretized by a mesh of triangular elements (Figure 2). Solutions of the two equations are coupled through the source term on the RHS of equation (1) and the boundary conditions on the pipe falls for equation (2) on the way that the continuity of heat flux on this mutual interface is preserved. ...
Similar publications
Citations
... Numerical solution is elaborated in more details in Tombarević and Vušanović [4]. Thanks to the fact that the solid domain is sweepable, it is meshed by triangular prism elements with required number of divisions along the depth of the borehole in order to appropriately take into account the temperature change of heat transfer fluid with depth. ...
This paper presents a quasi-three-dimensional CVFEM model of unsteady heat flow around a single U-tube borehole heat exchanger. The heat transfer model of the fluid circulating through the U tube is considered as one dimensional, while heat transfer through the pipe's wall, grout and the soil is considered as fully three dimensional. Equations of the mathematical model are simultaneously solved to arrive at the solution. The two components of the numerical model are separately verified through the comparison with available analytical solutions. Also, the integral model is verified against the available experimental data.
