minor fixes

thermosteam/_stream.py

@@ -1266,11 +1266,15 @@ def alpha(self) -> float:
     @property
     def rho(self) -> float:
         """Density [kg/m^3]."""
-        return fn.V_to_rho(self.V, self.MW)
+        V = self.V
+        if V is None: return V
+        return fn.V_to_rho(V, self.MW)
     @property
     def nu(self) -> float:
         """Kinematic viscosity [m^2/s]."""
-        return fn.mu_to_nu(self.mu, self.rho)
+        mu = self.mu
+        if mu is None: return mu
+        return fn.mu_to_nu(mu, self.rho)
     @property
     def Pr(self) -> float:
         """Prandtl number [-]."""

thermosteam/equilibrium/lle.py

@@ -223,7 +223,7 @@ def __call__(self, T, P=None, top_chemical=None, update=True, use_cache=True):
                 self._phi = phi = phase_fraction(z_mol, K, self._phi)
                 if phi >= 1.:
                     mol_l = mol
-                    mol_L = 0.
+                    mol_L = 0. * mol
                 else:
                     y = z_mol * K / (phi * K + (1 - phi))
                     mol_l = y * phi

thermosteam/separations.py

@@ -642,13 +642,6 @@ def lle(feed, top, bottom, top_chemical=None, efficiency=1.0, multi_stream=None)
         ms = feed.copy()
     ms.lle(feed.T, top_chemical=top_chemical)
     top_phase, bottom_phase = ms.phases
-    if not top_chemical:
-        rho_l = ms['l'].rho
-        rho_L = ms['L'].rho
-        top_l = rho_l < rho_L
-        if top_l:
-            top_phase = 'l'
-            bottom_phase = 'L'
     top.mol[:] = ms.imol[top_phase]
     bottom.mol[:] = ms.imol[bottom_phase]
     top.T = bottom.T = feed.T