.Buildings.Fluid.FixedResistances.BuriedPipes.GroundCoupling

Information

This model simulates the heat transfer between multiple buried pipes and the ground, using climate and soil information and the geometry of the pipes network.

The model can take any number of pipes, and can be discretized axially in any number of segments. Currently, the model only allows for pipes that run co-axially and parallel to the ground, and the axial segmentation must be the same for each pipe.

The heat transfer solution is based upon the potential flow theory and obtained by the use of "mirror-image" technique suggested by Eckert (1959). This technique is extended to a network with multiple pipes by Kusuda (1981) in the equation:

where:
L = pipe length [m]
k_s = soil thermal conductivity [W/(m.K)]
P_ij = geometric factor (see Buildings.Fluid.FixedResistances.BuriedPipes.BaseClasses.groundCouplingFactors for more information)
Q_i = net heat transfer from pipe i [W]
T_i = temperature at the exterior surface of pipe i [degC]
T_g = undisturbed ground temperature at the depth of the network. [degC]

This model relies on the following assumptions.

• Heat transfer is in steady state.
• The heat transfer is radial (no axial diffusion).
• The exterior surfaces for each pipe segment are isothermic planes.
• The ground surface is an isothermic plane.
• The soil conductivity is homogeneous and isotropic.

References

Eckert, E. R. G. (1959). Heat and Mass Transfer. McGraw-Hill Book Company.
Kusuda, T. (1981). Heat transfer analysis of underground heat and chilled-water distribution systems. National Bureau of Standards.

Revisions

• December 7, 2023, by Ettore Zanetti:
  Moved BuriedPipes package
  This is for issue 3431.
• March 17, 2021, by Baptiste Ravache:
  First implementation.