CoaxialPipe API Reference

geoloop.geoloopcore.CoaxialPipe.CoaxialPipe

Bases: CustomPipe

This class is used to evaluate the thermal resistance network of a Coaxial borehole.

In its default mode the object is marked by depth-indepedent design properties which can be altered, and can also access other methods from its baseclass CustomPipe.

It uses pygfunction of Cimmino and Cook [#Cimmino2024] for the determination of the thermal resistivity network of the borehole

It contains information regarding the physical dimensions and thermal characteristics of the pipes and the grout material, as well as methods (through its base class) to evaluate fluid temperatures and heat extraction rates based on the work of Hellstrom [#Single-Hellstrom1991]. Internal borehole thermal resistances are evaluated using the multipole method of Claesson and Hellstrom [#Single-Claesson2011b].

References

.. [#Cimmino2022] Cimmino, M., & Cook, J.C. (2022). pygfunction 2.2: New features and improvements in accuracy and computational efficiency. In Research Conference Proceedings, IGSHPA Annual Conference 2022 (pp. 45-52). International Ground Source Heat Pump Association. DOI: https://doi.org/10.22488/okstate.22.000015. .. [#Single-Hellstrom1991] Hellstrom, G. (1991). Ground heat storage. Thermal Analyses of Duct Storage Systems I: Theory. PhD Thesis. University of Lund, Department of Mathematical Physics. Lund, Sweden. .. [#Single-Claesson2011b] Claesson, J., & Hellstrom, G. (2011). Multipole method to calculate borehole thermal resistances in a borehole heat exchanger. HVAC&R Research, 17(6), 895-911.

__init__

__init__(
    r_in: ndarray | float,
    r_out: ndarray | float,
    borehole,
    k_g: float | ndarray,
    k_p: float | ndarray,
    k_s: float = 1.0,
    J: int = 2,
    m_flow: float = 1.0,
    T_f: float = 10.0,
    fluid_str: str = "Water",
    percent: float = 100.0,
    epsilon: float = 1e-06,
    ncalcsegments: int = 1,
    R_p: list[ndarray] | None = None,
) -> None

Initialize a coaxial borehole pipe model and compute its thermal and hydraulic properties.

Parameters:

Name	Type	Description	Default
r_in	float or ndarray	Inner radii of the coaxial pipes (m). If scalar, copied for both inlet and outlet pipes. (first radius is largest as this is corresponding to the inlet)	required
r_out	float or ndarray	Outer radii of the coaxial pipes (m). If scalar, copied for both inlet and outlet pipes.	required
borehole	Borehole	Borehole geometry object.	required
k_g	float or ndarray	Grout thermal conductivity (W/m·K). If array-like, represents values per segment.	required
k_p	float or ndarray	Pipe wall thermal conductivity (W/m·K).	required
k_s	float	Soil thermal conductivity (W/m·K). Default is 1.0.	1.0
J	int	Number of multipoles used in the multipole expansion. Default is 2.	2
m_flow	float	Total mass flow rate in the BHE (kg/s).	1.0
T_f	float	Fluid temperature at inlet (°C).	10.0
fluid_str	str	Working fluid name for thermal property lookup.	'Water'
percent	float	Concentration of glycol or other additive (%).	100.0
epsilon	float	Relative pipe roughness for hydraulic calculations.	1e-06
ncalcsegments	int	Number of depth segments used in thermal resistance evaluation.	1
R_p	list of ndarray	Precomputed pipe thermal resistances for each segment. If None, resistances are computed automatically. Default is empty list, and routines will calculate the resistivity based on the pipe dimensions and thermal conductivity.	None

Notes

• Creates a :class:gt.pipes.Coaxial object for use in pygfunction.
• Computes convective coefficients, fluid properties, and initial delta-circuit thermal resistance matrices.

create_coaxial

create_coaxial() -> gt.pipes.Coaxial

Return the underlying pygfunction :class:Coaxial object.

Returns:

Type	Description
Coaxial	The pygfunction coaxial borehole object representing the thermal resistance network.

init_thermal_resistances

init_thermal_resistances(
    k_g: ndarray, R_p: list[ndarray]
) -> None

Initialize pipe and grout thermal resistances for all borehole segments.

This routine is called from the B2G.runsimulation method, in order to generate thermal resistances based on actual segments determined by len(k_g) and len(R_p).

Parameters:

Name	Type	Description	Default
k_g	ndarray	Grout thermal conductivity values for each segment.	required
R_p	list of ndarray	Pipe thermal resistance values for each segment.	required

update_scaleflow

update_scaleflow(
    scaleflow: float = 1.0,
    forceupdate: bool = False,
    initialize_stored_coeff: bool = True,
) -> None

Update the scaling of flow rate and associated thermal resistance network.

This method adjusts the flow rate scaling and updates the thermal resistance network based on the new flow rate. Optionally, it can force an update and reinitialize stored coefficients.

Parameters:

Name	Type	Description	Default
scaleflow	float	Scaling factor for flow rate. Default is 1.0.	1.0
forceupdate	bool	If True, forces update of thermal resistances even if changes are small. Default is False.	False
initialize_stored_coeff	bool	If True, reinitializes stored thermal resistance coefficients. Default is True.	True

Returns:

Type	Description
None	Updates internal state in place.

get_temperature_depthvar

get_temperature_depthvar(
    T_f_in: float,
    signpower: float,
    Rs: ndarray,
    soil_props: SoilProperties,
    nsegments: int = 10,
) -> tuple

Compute outlet temperature and thermal performance for depth-variable borehole.

This method partitions the borehole depth into segments and iteratively computes fluid temperatures, borehole temperatures, and heat flows based on thermal resistances and soil properties.

Parameters:

Name	Type	Description	Default
T_f_in	float	Inlet fluid temperature (°C).	required
signpower	float	Sign and magnitude for initial power guess.	required
Rs	ndarray	Array of thermal resistances for each segment.	required
soil_props	SoilProperties	Object defining soil properties and temperature gradient.	required
nsegments	int	Number of depth segments. Default is 10.	10

Returns:

Name	Type	Description
T_f_out	float	Outlet fluid temperature (°C).
power	float	Heat extraction or injection power (W).
Reff	float	Effective thermal resistance (m·K/W).
ptemp	ndarray	Fluid temperatures per segment.
Tb	ndarray	Borehole temperatures per segment.
qbz	ndarray	Heat flow per segment (W).