Pipe¶
-
class
pygld.
Pipe
(di, do, material=None)¶ The
Pipe
class holds the geometry and material properties of the pipes used in the construction of ground-loop heat exchangers. The inner and outer diameters of the pipe in cm must be passed as arguments when instantiatingPipe
. These values can afterward be accessed or changed with thedi
anddo
propertiesThe thermophysical properties of the pipe are held in a
PipeMaterial
object that can be accessed with thematerial
property or set withset_material()
. The optional argument ‘material’ can be used to pass a customPipeMaterial
when instantiating aPipe
. If noPipeMaterial
is provided when instantiatingPipe
, the pipe’smaterial
will be set to that of a standard HDPE pipe by default, with a thermal conductivity of 0.4 W/m·k and a volumetric heat capacity of 1500 J/m³·K. These values can be changed afterward by setting directly the propertiesPipeMaterial.kth
andPipeMaterial.Cp
of the pipe’smaterial
.An Example is available at the end of this section.
Geometry¶
-
Pipe.
di
¶ Inner diameter of the pipe in cm.
Get or set the inner diameter of the pipe as a single positive float value.
-
Pipe.
do
¶ Outer diameter of the pipe in cm.
Get or set the outer diameter of the pipe as a single positive float value.
-
Pipe.
wt
¶ Return the pipe wall thickness in cm calculated as:
where and are, respectively, the outer and inner diameter of the pipe in cm.
-
Pipe.
Ai
¶ Return the inner area of the pipe in cm² calculated as:
where is the inner diameter of the pipe.
-
Pipe.
Ao
¶ Return the inner area of the pipe in cm² calculated as:
where is the outer diameter of the pipe.
Material and thermal resistance¶
-
Pipe.
material
¶ Return the
PipeMaterial
of the pipe.
-
Pipe.
set_material
(material)¶ Set the
PipeMaterial
of the pipe.
-
Pipe.
Rcond
¶ Return the conductive thermal resistance of the pipe in m·K/W calculated as:
where and are, repectively, the inner and outer diameter of the pipe in m and is its thermal conductivity in W/m·k.
References¶
Pipe conductive thermal resistance :
- Hellström, G. 1991. Ground Heat Storage - Thermal Analyses of Duct
- Storage Systems. Ph.D. thesis. University of Lund. Department of mathematical physics, Lund, Sweden. Eq.8.2, p.75.
Example¶
Import and instantiate the HeatPump
class:
>>> from pygld import Pipe
>>> pipe = Pipe(di=3.39852, do=4.2164)
>>> print(pipe)
Inner diameter: 3.40 cm
Outer diameter: 4.22 cm
Wall thickness: 0.41 cm
Inner area: 9.07 cm²
Outer area: 13.96 cm²
Pipe material: HDPE
Thermal conductivity: 0.400 W/m·k
Volumetric heat capacity: 1500 J/m³·K
Thermal diffusivity: 2.67e-04 m²/s
Conductive thermal resistance: 0.08580 m·K/W
Change and print the thermal properties of the pipe. This must be done through
the pipe’s material
as:
>>> pipe.material.kth = 0.43
>>> pipe.material.Cp = 0.1540
>>> print(pipe.material)
Pipe material: User Defined
Thermal conductivity: 0.430 W/m·k
Volumetric heat capacity: 1540 J/m³·K
Thermal diffusivity: 2.79e-04 m²/s