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Table 2 Applied parameters in the numerical model
From: Modeling neighborhood-scale shallow geothermal energy utilization: a case study in Berlin
Parameter | Symbol | Value | Unit |
|---|---|---|---|
BHE type | − | 2U | − |
BHE length | L | 99 | \(\mathrm {m}\) |
Borehole diameter | D | 0.16 | \(\mathrm {m}\) |
Pipe distance | w | 0.07 | \(\mathrm {m}\) |
Inlet pipe diameter | \(d_{\text {in}}\) | 0.032 | \(\mathrm {m}\) |
Inlet pipe wall thickness | \(b_{\text {in}}\) | 0.003 | \(\mathrm {m}\) |
Inlet pipe thermal conductivity | \(\lambda _{\text {in}}\) | 0.42 | \(\mathrm {Wm^{-1}K^{-1}}\) |
Outlet pipe diameter | \(d_{\text {out}}\) | 0.032 | \(\mathrm {m}\) |
Outlet pipe wall thickness | \(b_{\text {out}}\) | 0.003 | \(\mathrm {m}\) |
Outlet pipe thermal conductivity | \(\lambda _{\text {out}}\) | 0.42 | \(\mathrm {Wm^{-1}K^{-1}}\) |
Grout thermal conductivity | \(\lambda _{g}\) | 2.0 | \(\mathrm {Wm^{-1}K^{-1}}\) |
Undisturbed subsurface temperature | \(\theta _{s}\) | 11.6 | \(^\circ \mathrm {C}\) |
Subsurface thermal conductivity | \(\lambda _{s}\) | cf. Table 3 | \(\mathrm {Wm^{-1}K^{-1}}\) |
Subsurface mean thermal conductivity* | \(\lambda _{s, mean}\) | 2.5 | \(\mathrm {Wm^{-1}K^{-1}}\) |
Subsurface volumetric heat capacity | \(\rho _{s} c_{s}\) | cf. Table 3 | \(\mathrm {MJ m^{-3} K^{-1}}\) |
Refrigerant volumetric heat capacity | \(\rho _{r}\)c\(_{r}\) | 4.0 | \(\mathrm {MJ m^{-3} K^{-1}}\) |
Refrigerant density | \(\rho _{r}\) | 1052 | \(\mathrm {kg m^{-3}}\) |
Refrigerant thermal conductivity | \(\lambda _{r}\) | 0.48 | \(\mathrm {Wm^{-1}K^{-1}}\) |
Refrigerant dynamic viscosity | \(\mu _{r}\) | \(5.2\times 10^{-3}\) | \(\mathrm {kg m^{-1}s^{-1}}\) |
Refrigerant flow rate per BHE | \(\dot{V}_r\) | \(4.63\times 10^{-4}\) | \(\mathrm {m^3s^{-1}}\) |
Borehole thermal resistance* | \(R_b\) | 0.09 | \(\mathrm {K m W^{-1}}\) |