 public double calcDensity() {
      //This class need to be changed to the Costald method
        double tempVar = 0.0;
        double acsFaactMix =0;    
        for (int i = 0; i < liquidPhase.getPhase().getNumberOfComponents(); i++) {
              acsFaactMix += liquidPhase.getPhase().getComponents()[i].getAcentricFactor()|*Math.sqrt(liquidPhase.getPhase().getComponents()[i].getx())


acsFaactMix  Math.pow(acsFaactMix, 2.0)

              liquidPhase.getPhase().getComponents()[i].getCriticalVolume()
              liquidPhase.getPhase().getComponents()[i].getTC()
              liquidPhase.getPhase().getComponents()[i].PC()
              liquidPhase.getPhase().getComponents()[i].getAcentricFactor()
              liquidPhase.getPhase().getTemperature()

              liquidPhase.getPhase().getComponent(i).getTriplePointPressure()

                tempVar += liquidPhase.getPhase().getComponents()[i].getx()
                        * (liquidPhase.getPhase().getComponents()[i].getVolumeCorrection()
                                + liquidPhase.getPhase().getComponents()[i].getVolumeCorrectionT()
                                        * (liquidPhase.getPhase().getTemperature() - 288.15));
        }
        // System.out.println("density correction tempvar " + tempVar);
        return 1.0 / (liquidPhase.getPhase().getMolarVolume() - tempVar)
                * liquidPhase.getPhase().getMolarMass() * 1.0e5;
    }


     }

  @Test
  void testCalcDensity() {
    testSystem.getPhase("oil").getPhysicalProperties().setDensityModel("Costald");
    double costaldDensity = testSystem.getPhase("oil").getPhysicalProperties().calcDensity();
    double costaldVolume = 1.0/costaldDensity * testSystem.getPhase("oil").getMolarMass() *1e6;
    assertEquals(99.05, costaldVolume, 1e-3);
  }
}
