Add API for MIFT Boundary Condition #315

mitchute · 2025-04-09T17:52:58Z

PR adds an API for computing g-functions using static inputs based on the MIFT boundary condition. As a reminder, PR #308 added a parallel API for the UHTR and UBWT boundary conditions. Since the input requirements are so different from the two schemes (MIFT vs UHTR and UBWT), rather than trying to unify the API, IMO it looks more straightforward for users to pick which one they want based on the BC and level of inputs they are interested in providing. The RR is still somewhat "drafty," and somethings like the use of Enum and the right sets of input arguments to expose need to be pinned down. The code is functional for the current test cases, but we likely should be testing and exposing more, as needed to get to the appropriate basic functionality level. We could add lots of fanciness on top after that.

Feel free to review/discuss and we can go from there.

MassimoCimmino · 2025-04-21T08:07:41Z

Reading through the code, it seems to me the API has two objectives:

To follow-up on Create API for computing g-function values from static inputs #308 and implement an API that uses the Network object to evaluate g-functions.
To facilitate the creation of Network (and Pipe) objects using static inputs and automate the evaluation of the required resistances.

For consistensy, my opinion is that (1.) should be addressed by implementing a evaluate_g_function method in the Network class, analogous to the method now implemented in the Borefield class.

My proposal for (2.) is to create a new class GroundHeatExchanger (or something similar) that encapsulates the cross-sectional geometry of the boreholes, evaluates thermal resistances, and includes methods to create Pipe or Network instances. Long-term, this could conveniently deal with #304 and also solve an issue of Network initialization where the multipole solution is evaluated nBoreholes times even when the geometry is the same. I have code from another project that could be adapted for implementation into pygfunction.

mitchute · 2025-04-22T00:15:16Z

@MassimoCimmino thanks for your input. We can update this to adapt to your suggestions.

…unction generaton

mitchute

@MassimoCimmino thanks for your feedback. These updates are a first pass at addressing your suggestions.

mitchute · 2025-05-14T18:13:33Z

pygfunction/enums.py

+class GHEType(Enum):
+    BOREHOLE = auto()
+    BOREFIElD = auto()
+    NETWORK = auto()


Needed this to break circular import issues.

Edit: I just noticed the lower case l in BOREFIElD. Need to update that.

mitchute · 2025-05-14T18:15:31Z

pygfunction/gfunction.py

+        # needed to break circular imports
+        from .solvers import (
+            Detailed,
+            Equivalent,
+            Similarities
+        )


There's some lingering circular dependencies among the files. Needed to import these here to break the circular import problems.

mitchute · 2025-05-14T18:15:53Z

pygfunction/gfunction.py

-        if isinstance(boreholes_or_network, Borehole):
+        if boreholes_or_network.ghe_type == GHEType.BOREHOLE:


Related to circular import issues

mitchute · 2025-05-14T18:17:05Z

pygfunction/gfunction.py

-        if isinstance(boreholes_or_network, Network):
+        elif boreholes_or_network.ghe_type == GHEType.NETWORK:


It seemed to me like these should be chained if-else statements, not a series of if blocks, since they didn't return early.

mitchute · 2025-05-14T18:17:43Z

pygfunction/gfunction.py

-def equal_inlet_temperature(
-        boreholes, UTubes, m_flow_borehole, cp_f, time, alpha,
-        kind='linear', nSegments=8, segment_ratios=segment_ratios,
-        use_similarities=True, disTol=0.01, tol=1.0e-6, dtype=np.double,
-        disp=False, **kwargs):


These are all tagged for deprecation. I removed them so I didn't have to continue to deal with circular import problems.

mitchute · 2025-05-14T18:18:58Z

pygfunction/ground_heat_exchanger.py

+class GroundHeatExchanger:
+
+    def __init__(self,
+                 H: npt.ArrayLike,
+                 D: npt.ArrayLike,


New GHE class. Constructor and evaluate_g_function arguments need a more thorough review.

mitchute · 2025-05-14T18:19:18Z

pygfunction/networks.py

-        self._stored_coefficients = [() for i in range(nMethods)]
+        self._stored_coefficients = [() for _ in range(nMethods)]
        self._stored_m_flow_cp = [np.empty(self.nInlets)*np.nan
-                                  for i in range(nMethods)]
-        self._stored_nSegments = [np.nan for i in range(nMethods)]
-        self._stored_segment_ratios = [np.nan for i in range(nMethods)]
+                                  for _ in range(nMethods)]
+        self._stored_nSegments = [np.nan for _ in range(nMethods)]
+        self._stored_segment_ratios = [np.nan for _ in range(nMethods)]


unused variables

mitchute · 2025-05-14T18:19:48Z

pygfunction/pipes.py

+def compute_R_fp(
+        pipe_type: PipeType, m_flow_borehole: float, r_in: Union[float, tuple, list],
+        r_out: Union[float, tuple, list], k_p: float, epsilon: float, fluid: Fluid) -> float:
+    if pipe_type in [PipeType.SINGLEUTUBE, PipeType.DOUBLEUTUBESERIES]:


Some worker functions

mitchute · 2025-05-14T18:20:37Z

pygfunction/ground_heat_exchanger.py

+                 k_p: float,
+                 fluid_name: str,
+                 fluid_concentration_pct: float,
+                 m_flow_ghe,


Would prefer to not have to pass this in to the constructor, but that's going to require some more work.

mitchute · 2025-05-14T18:21:36Z

tests/gfunction_test.py

+@pytest.mark.parametrize("field, boundary_condition, method, opts, pipe_type, m_flow_network, expected", [
+        #  'equivalent' solver - unequal segments - UBWT - single u-tube
+        ('single_borehole', 'UBWT', 'equivalent', 'unequal_segments', 'single_Utube', 0.05, np.array([5.59717446, 6.36257605, 6.60517223])),
+        ('single_borehole_short', 'UBWT', 'equivalent', 'unequal_segments', 'single_Utube', 0.05, np.array([4.15784411, 4.98477603, 5.27975732])),
+        ('ten_boreholes_rectangular', 'UBWT', 'equivalent', 'unequal_segments', 'single_Utube', 0.25, np.array([10.89935004, 17.09864925, 19.0795435])),
+        #  'equivalent' solver - unequal segments - UHTR - single u-tube
+        ('single_borehole', 'UHTR', 'equivalent', 'unequal_segments', 'single_Utube', 0.05, np.array([5.61855789, 6.41336758, 6.66933682])),
+        ('single_borehole_short', 'UHTR', 'equivalent', 'unequal_segments', 'single_Utube', 0.05, np.array([4.18276733, 5.03671562, 5.34369772])),
+        ('ten_boreholes_rectangular', 'UHTR', 'equivalent', 'unequal_segments', 'single_Utube', 0.25, np.array([11.27831804, 18.48075762, 21.00669237])),
+        #  'equivalent' solver - unequal segments - MIFT - single u-tube
+        ('single_borehole', 'MIFT', 'equivalent', 'unequal_segments', 'single_Utube', 0.05,  np.array([5.76597302, 6.51058473, 6.73746895])),
+        ('single_borehole_short', 'MIFT', 'equivalent', 'unequal_segments', 'single_Utube', 0.05, np.array([4.17105954, 5.00930075, 5.30832133])),
+        ('ten_boreholes_rectangular', 'MIFT', 'equivalent', 'unequal_segments', 'single_Utube', 0.25, np.array([12.66229998, 18.57852681, 20.33535907])),
+        #  'equivalent' solver - unequal segments - MIFT - double u-tube parallel
+        ('single_borehole', 'MIFT', 'equivalent', 'unequal_segments', 'double_Utube_parallel', 0.05, np.array([6.47497545, 7.18728277, 7.39167598])),
+        ('single_borehole_short', 'MIFT', 'equivalent', 'unequal_segments', 'double_Utube_parallel', 0.05, np.array([4.17080765, 5.00341368, 5.2989709])),
+        ('ten_boreholes_rectangular', 'MIFT', 'equivalent', 'unequal_segments', 'double_Utube_parallel', 0.25, np.array([15.96448954, 21.43320976, 22.90761598])),
+        #  'equivalent' solver - unequal segments - MIFT - double u-tube series
+        ('single_borehole', 'MIFT', 'equivalent', 'unequal_segments', 'double_Utube_series', 0.05, np.array([5.69118368, 6.44386342, 6.67721347])),
+        ('single_borehole_short', 'MIFT','equivalent', 'unequal_segments', 'double_Utube_series', 0.05, np.array([4.16750616, 5.00249502, 5.30038701])),
+        ('ten_boreholes_rectangular', 'MIFT', 'equivalent', 'unequal_segments', 'double_Utube_series', 0.25, np.array([11.94256058, 17.97858109, 19.83460231])),
+        #  'equivalent' solver - unequal segments - MIFT - double u-tube series asymmetrical
+        ('single_borehole', 'MIFT', 'equivalent', 'unequal_segments', 'double_Utube_series_asymmetrical', 0.05, np.array([5.69174709, 6.4441862 , 6.67709693])),
+        ('single_borehole_short', 'MIFT', 'equivalent', 'unequal_segments', 'double_Utube_series_asymmetrical', 0.05, np.array([4.16851817, 5.00453267, 5.30282913])),
+        ('ten_boreholes_rectangular', 'MIFT', 'equivalent', 'unequal_segments', 'double_Utube_series_asymmetrical', 0.25, np.array([11.96927941, 18.00481705, 19.856554])),
+        #  'equivalent' solver - unequal segments - MIFT - double u-tube series asymmetrical
+        ('single_borehole', 'MIFT', 'equivalent', 'unequal_segments', 'double_Utube_series_asymmetrical', 0.05, np.array([5.69174709, 6.4441862, 6.67709693])),
+        ('single_borehole_short', 'MIFT', 'equivalent', 'unequal_segments', 'double_Utube_series_asymmetrical', 0.05, np.array([4.16851817, 5.00453267, 5.30282913])),
+        ('ten_boreholes_rectangular', 'MIFT', 'equivalent', 'unequal_segments', 'double_Utube_series_asymmetrical', 0.25, np.array([11.96927941, 18.00481705, 19.856554])),
+        #  'equivalent' solver - unequal segments - MIFT - coaxial annular inlet
+        ('single_borehole', 'MIFT', 'equivalent', 'unequal_segments', 'coaxial_annular_in', 0.05, np.array([6.10236427, 6.77069069, 6.95941276])),
+        ('single_borehole_short', 'MIFT', 'equivalent', 'unequal_segments', 'coaxial_annular_in', 0.05, np.array([4.06874781, 4.89701125, 5.19157017])),
+        ('ten_boreholes_rectangular', 'MIFT', 'equivalent', 'unequal_segments', 'coaxial_annular_in', 0.25, np.array([16.03433989, 21.18241954, 22.49479982])),
+        #  'equivalent' solver - unequal segments - MIFT - coaxial annular outlet
+        ('single_borehole', 'MIFT', 'equivalent', 'unequal_segments', 'coaxial_annular_out', 0.05, np.array([6.10236427, 6.77069069, 6.95941276])),
+        ('single_borehole_short', 'MIFT', 'equivalent', 'unequal_segments', 'coaxial_annular_out', 0.05, np.array([4.06874781, 4.89701125, 5.19157017])),
+        ('ten_boreholes_rectangular', 'MIFT', 'equivalent', 'unequal_segments', 'coaxial_annular_out', 0.25, np.array([16.03433989, 21.18241954, 22.49510883])),
+    ])


Some tests to verify things are nominally functional. Expected values pulled from existing tests from above.

mitchute added 8 commits April 8, 2025 11:57

wip stubbing out MIFT api

426b041

initial working version of API with MIFT boundary condition

89c4578

minor cleanups

53c3e0c

add double u to MIFT API

a1bed43

add coaxial, fix inadvertently broken tests

c3d2a55

fix merge issue

f344137

touchup

a434c09

pull resistance calcs out of loop

c0321c2

MassimoCimmino mentioned this pull request Apr 25, 2025

Create API to compute g-function from Network class #318

Open

mitchute added 2 commits May 13, 2025 10:23

Merge branch 'master' into add_mift_api

79251ca

create ground heat exchanger file, create methods for generalized g-f…

5515d19

…unction generaton

mitchute commented May 14, 2025

View reviewed changes

mitchute added 2 commits June 23, 2025 10:06

allow separate coaxial pipe conducitivity values

36e884e

ensure arrays for coaxial pipe radii

157e8ff

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		if isinstance(boreholes_or_network, Borehole):
		if boreholes_or_network.ghe_type == GHEType.BOREHOLE:

		if isinstance(boreholes_or_network, Network):
		elif boreholes_or_network.ghe_type == GHEType.NETWORK:

Add API for MIFT Boundary Condition #315

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