补充氦气Peng-Robinson物性库

tests/test_peng_robinson.py

@@ -0,0 +1,65 @@
+from __future__ import annotations
+
+import unittest
+
+from PythonModels.core.peng_robinson import AIR_PR, HELIUM_PR, NITROGEN_PR, PengRobinsonFluid
+
+
+class PengRobinsonTest(unittest.TestCase):
+    def test_helium_near_ideal_at_atmospheric_condition(self) -> None:
+        z = HELIUM_PR.compressibility_factor(101_325.0, 300.0)
+        density = HELIUM_PR.density(101_325.0, 300.0)
+
+        self.assertAlmostEqual(z, 1.0, delta=1.0e-3)
+        self.assertAlmostEqual(density, 0.1625, delta=0.002)
+
+    def test_helium_density_pressure_round_trip(self) -> None:
+        pressure = 15.3e6
+        temperature = 293.15
+        density = HELIUM_PR.density(pressure, temperature)
+
+        self.assertGreater(HELIUM_PR.compressibility_factor(pressure, temperature), 1.0)
+        self.assertAlmostEqual(
+            HELIUM_PR.pressure_from_density(temperature, density),
+            pressure,
+            delta=pressure * 1.0e-12,
+        )
+
+    def test_air_reference_remains_available_for_other_models(self) -> None:
+        z = AIR_PR.compressibility_factor(101_325.0, 300.0)
+        density = AIR_PR.density(101_325.0, 300.0)
+
+        self.assertAlmostEqual(z, 1.0, delta=1.0e-3)
+        self.assertAlmostEqual(density, 1.177, delta=0.01)
+
+    def test_nitrogen_can_return_multiple_roots(self) -> None:
+        roots = NITROGEN_PR.compressibility_roots(1.0e6, 100.0)
+
+        self.assertEqual(len(roots), 3)
+        self.assertLess(roots[0], roots[-1])
+        self.assertEqual(NITROGEN_PR.compressibility_factor(1.0e6, 100.0, phase="liquid"), roots[0])
+        self.assertEqual(NITROGEN_PR.compressibility_factor(1.0e6, 100.0, phase="vapor"), roots[-1])
+
+    def test_custom_fluid_can_be_defined_explicitly(self) -> None:
+        fluid = PengRobinsonFluid(
+            name="custom_helium",
+            molar_mass=0.004002602,
+            critical_temperature=5.1953,
+            critical_pressure=227_460.0,
+            acentric_factor=-0.385,
+        )
+
+        self.assertAlmostEqual(fluid.specific_gas_constant, 2077.3, delta=0.5)
+        self.assertAlmostEqual(fluid.compressibility_factor(1.0e6, 298.15), HELIUM_PR.compressibility_factor(1.0e6, 298.15))
+
+    def test_rejects_invalid_states(self) -> None:
+        with self.assertRaises(ValueError):
+            HELIUM_PR.compressibility_factor(0.0, 300.0)
+        with self.assertRaises(ValueError):
+            HELIUM_PR.density(101_325.0, 0.0)
+        with self.assertRaises(ValueError):
+            HELIUM_PR.pressure_from_density(300.0, -1.0)
+
+
+if __name__ == "__main__":
+    unittest.main()