- Change parameters in pressure drop calculation

- Add U-bend for accuracy

CHANGELOG.md

@@ -12,6 +12,10 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 - Added support for DHW profiles in optimisation (issue #272).
 - Added Prandtl number to FluidData class (issue #326).
 
+## Changed
+
+- Added U-bend to the pressure drop calculation of the pipe (issue #332).
+
 ## [2.3.1] - 2025-01-23
 
 ### Added

GHEtool/VariableClasses/PipeData/CoaxialPipe.py

@@ -140,7 +140,7 @@ def Re(self, fluid_data: FluidData) -> float:
         # Reynolds number
         return fluid_data.rho * V * D_h / fluid_data.mu
 
-    def pressure_drop(self, fluid_data: FluidData, borehole_depth: float) -> float:
+    def pressure_drop(self, fluid_data: FluidData, borehole_length: float) -> float:
         """
         Calculates the pressure drop across the entire borehole.
         It assumed that the U-tubes are all connected in parallel.
@@ -149,8 +149,8 @@ def pressure_drop(self, fluid_data: FluidData, borehole_depth: float) -> float:
         ----------
         fluid_data: FluidData
             Fluid data
-        borehole_depth : float
-            Borehole depth [m]
+        borehole_length : float
+            Borehole length [m]
 
         Returns
         -------
@@ -167,7 +167,10 @@ def pressure_drop(self, fluid_data: FluidData, borehole_depth: float) -> float:
         # Darcy-Wiesbach friction factor
         fd = gt.pipes.fluid_friction_factor_circular_pipe(
             fluid_data.mfr, r_h, fluid_data.mu, fluid_data.rho, self.epsilon)
-        return (fd * (borehole_depth * 2) / (2 * r_h) * fluid_data.rho * V ** 2 / 2) / 1000
+
+        # add 0.2 for the local losses
+        # (source: https://www.engineeringtoolbox.com/minor-loss-coefficients-pipes-d_626.html)
+        return ((fd * (borehole_length * 2) / (2 * r_h) + 0.2) * fluid_data.rho * V ** 2 / 2) / 1000
 
     def draw_borehole_internal(self, r_b: float) -> None:
         """

GHEtool/VariableClasses/PipeData/MultipleUTube.py

@@ -133,7 +133,7 @@ def Re(self, fluid_data: FluidData) -> float:
             (pi * self.r_in ** 2)
         return fluid_data.rho * u * self.r_in * 2 / fluid_data.mu
 
-    def pressure_drop(self, fluid_data: FluidData, borehole_depth: float) -> float:
+    def pressure_drop(self, fluid_data: FluidData, borehole_length: float) -> float:
         """
         Calculates the pressure drop across the entire borehole.
         It assumed that the U-tubes are all connected in parallel.
@@ -142,8 +142,8 @@ def pressure_drop(self, fluid_data: FluidData, borehole_depth: float) -> float:
         ----------
         fluid_data: FluidData
             Fluid data
-        borehole_depth : float
-            Borehole depth [m]
+        borehole_length : float
+            Borehole length [m]
 
         Returns
         -------
@@ -161,7 +161,9 @@ def pressure_drop(self, fluid_data: FluidData, borehole_depth: float) -> float:
         A = pi * self.r_in ** 2
         V = (fluid_data.vfr / 1000) / A / self.number_of_pipes
 
-        return (fd * (borehole_depth * 2) / (2 * self.r_in) * fluid_data.rho * V ** 2 / 2) / 1000
+        # add 0.2 for the local losses
+        # (source: https://www.engineeringtoolbox.com/minor-loss-coefficients-pipes-d_626.html)
+        return ((fd * (borehole_length * 2) / (2 * self.r_in) + 0.2) * fluid_data.rho * V ** 2 / 2) / 1000
 
     def draw_borehole_internal(self, r_b: float) -> None:
         """

GHEtool/VariableClasses/PipeData/_PipeData.py

@@ -81,7 +81,7 @@ def Re(self, fluid_data: FluidData) -> float:
         """
 
     @abc.abstractmethod
-    def pressure_drop(self, fluid_data: FluidData, borehole_depth: float) -> float:
+    def pressure_drop(self, fluid_data: FluidData, borehole_length: float) -> float:
         """
         Calculates the pressure drop across the entire borehole.
         It assumed that the U-tubes are all connected in parallel.
@@ -90,8 +90,8 @@ def pressure_drop(self, fluid_data: FluidData, borehole_depth: float) -> float:
         ----------
         fluid_data: FluidData
             Fluid data
-        borehole_depth : float
-            Borehole depth [m]
+        borehole_length : float
+            Borehole length [m]
 
         Returns
         -------

GHEtool/test/unit-tests/test_pipedata.py

@@ -214,10 +214,10 @@ def test_pressure_drop():
     fluid_data = FluidData(0.3, 0.568, 998, 4180, 1e-3)
     single = MultipleUTube(1, 0.02, 0.02, 0.4, 0.05, 1)
     double = MultipleUTube(1, 0.013, 0.016, 0.4, 0.05, 2)
-    assert np.isclose(single.pressure_drop(fluid_data, 100), 4.4688388696204555)
-    assert np.isclose(double.pressure_drop(fluid_data, 100), 10.339838859988387)
+    assert np.isclose(single.pressure_drop(fluid_data, 100), 4.474549607676448)
+    assert np.isclose(double.pressure_drop(fluid_data, 100), 10.347836812519452)
     coaxial = CoaxialPipe(r_in_in, r_in_out, r_out_in, r_out_out, k_p, k_g, is_inner_inlet=True)
-    assert np.isclose(coaxial.pressure_drop(fluid_data, 100), 0.16366613552554135)
+    assert np.isclose(coaxial.pressure_drop(fluid_data, 100), 0.1639237572210245)
 
 
 def test_repr_():