add use of unit for molar volume

src/main/java/neqsim/thermo/phase/Phase.java

@@ -46,14 +46,12 @@ public abstract class Phase implements PhaseInterface {
 
   /**
    * Mole fraction of this phase of system.
-   * <code>beta = numberOfMolesInPhase/numberOfMolesInSystem</code>. NB!
-   * numberOfMolesInSystem is
+   * <code>beta = numberOfMolesInPhase/numberOfMolesInSystem</code>. NB! numberOfMolesInSystem is
    * not known to the phase.
    */
   double beta = 1.0;
   /**
-   * Number of moles in phase.
-   * <code>numberOfMolesInPhase = numberOfMolesInSystem*beta</code>. NB!
+   * Number of moles in phase. <code>numberOfMolesInPhase = numberOfMolesInSystem*beta</code>. NB!
    * numberOfMolesInSystem is not known to the phase.
    */
   public double numberOfMolesInPhase = 0;
@@ -103,7 +101,7 @@ public Phase clone() {
    * addcomponent. Increase number of components and add moles to phase.
    * </p>
    *
-   * @param name  Name of component to add.
+   * @param name Name of component to add.
    * @param moles Number of moles of component to add to phase.
    */
   public void addComponent(String name, double moles) {
@@ -179,8 +177,8 @@ public void addMoles(int component, double dn) {
   public void addMolesChemReac(int component, double dn, double totdn) {
     if ((numberOfMolesInPhase + dn) / numberOfMolesInPhase < -1e-10) {
       String msg = "will lead to negative number of moles in phase." + (numberOfMolesInPhase + dn);
-      neqsim.util.exception.InvalidInputException ex = new neqsim.util.exception.InvalidInputException(this,
-          "addMolesChemReac", "dn", msg);
+      neqsim.util.exception.InvalidInputException ex =
+          new neqsim.util.exception.InvalidInputException(this, "addMolesChemReac", "dn", msg);
       throw new RuntimeException(ex);
     }
     numberOfMolesInPhase += dn;
@@ -287,7 +285,8 @@ public double getPressure() {
   /** {@inheritDoc} */
   @Override
   public final double getPressure(String unit) {
-    neqsim.util.unit.PressureUnit presConversion = new neqsim.util.unit.PressureUnit(getPressure(), "bara");
+    neqsim.util.unit.PressureUnit presConversion =
+        new neqsim.util.unit.PressureUnit(getPressure(), "bara");
     return presConversion.getValue(unit);
   }
 
@@ -496,11 +495,11 @@ public double calcA(PhaseInterface phase, double temperature, double pressure, i
    * calcA.
    * </p>
    *
-   * @param comp        a int
-   * @param phase       a {@link neqsim.thermo.phase.PhaseInterface} object
+   * @param comp a int
+   * @param phase a {@link neqsim.thermo.phase.PhaseInterface} object
    * @param temperature a double
-   * @param pressure    a double
-   * @param numbcomp    a int
+   * @param pressure a double
+   * @param numbcomp a int
    * @return a double
    */
   public double calcA(int comp, PhaseInterface phase, double temperature, double pressure,
@@ -582,6 +581,23 @@ public double getMolarVolume() {
     return molarVolume;
   }
 
+  /** {@inheritDoc} */
+  @Override
+  public double getMolarVolume(String unit) {
+    double conversionFactor = 1.0;
+    switch (unit) {
+      case "m3/mol":
+        conversionFactor = 1.0;
+        break;
+      case "litre/mol":
+        conversionFactor = 1000.0;
+        break;
+      default:
+        throw new RuntimeException("unit not supported " + unit);
+    }
+    return getMolarMass() / getDensity("kg/m3") * conversionFactor;
+  }
+
   /** {@inheritDoc} */
   @Override
   public int getNumberOfComponents() {
@@ -1230,7 +1246,7 @@ public void initRefPhases(boolean onlyPure) {
    * </p>
    *
    * @param onlyPure a boolean
-   * @param name     a {@link String} object
+   * @param name a {@link String} object
    */
   public void initRefPhases(boolean onlyPure, String name) {
     refPhase = new PhaseInterface[numberOfComponents];
@@ -1284,7 +1300,7 @@ public void initRefPhases(boolean onlyPure, String name) {
    * getLogPureComponentFugacity.
    * </p>
    *
-   * @param k    a int
+   * @param k a int
    * @param pure a boolean
    * @return a double
    */
@@ -1826,8 +1842,7 @@ public void setPhysicalPropertyType(int physicalPropertyType) {
   /** {@inheritDoc} */
   @Override
   public void setParams(PhaseInterface phase, double[][] alpha, double[][] Dij, double[][] DijT,
-      String[][] mixRule, double[][] intparam) {
-  }
+      String[][] mixRule, double[][] intparam) {}
 
   /** {@inheritDoc} */
   @Override
@@ -1923,8 +1938,7 @@ public final void setBeta(double b) {
 
   /** {@inheritDoc} */
   @Override
-  public void setMixingRuleGEModel(String name) {
-  }
+  public void setMixingRuleGEModel(String name) {}
 
   /** {@inheritDoc} */
   @Override
@@ -2111,7 +2125,8 @@ public double[] getProperties_GERG2008() {
   /** {@inheritDoc} */
   @Override
   public double getDensity_AGA8() {
-    neqsim.thermo.util.GERG.NeqSimAGA8Detail test = new neqsim.thermo.util.GERG.NeqSimAGA8Detail(this);
+    neqsim.thermo.util.GERG.NeqSimAGA8Detail test =
+        new neqsim.thermo.util.GERG.NeqSimAGA8Detail(this);
     return test.getDensity();
   }
 

src/main/java/neqsim/thermo/phase/PhaseInterface.java

@@ -399,6 +399,16 @@ public default void init(double totalNumberOfMoles, int numberOfComponents, int
    */
   public double getMolarVolume();
 
+  /**
+   * method to return molar volume of the fluid:
+   * eventual volume correction included.
+   * 
+   * @param unit Supported units are m3/mol, litre/mol
+   *
+   * @return molar volume volume in unit
+   */
+  public double getMolarVolume(String unit);
+
   /**
    * method to return flow rate of a phase.
    *

src/main/java/neqsim/thermo/system/SystemInterface.java

@@ -1889,6 +1889,16 @@ public double calcBeta()
    */
   public double getMolarVolume();
 
+  /**
+   * method to return molar volume of the fluid:
+   * eventual volume correction included.
+   * 
+   * @param unit Supported units are m3/mol, litre/mol
+   *
+   * @return molar volume volume in unit
+   */
+  public double getMolarVolume(String unit);
+
   /**
    * Get molar mass of system.
    *

src/main/java/neqsim/thermo/system/SystemThermo.java

@@ -2833,6 +2833,16 @@ public double getEntropy(String unit) {
     return refEntropy * conversionFactor;
   }
 
+  /** {@inheritDoc} */
+  @Override
+  public double getMolarVolume(String unit) {
+    double volume = 0;
+    for (int i = 0; i < numberOfPhases; i++) {
+      volume += beta[phaseIndex[i]] * getPhase(i).getMolarVolume(unit);
+    }
+    return volume;
+  }
+
   /** {@inheritDoc} */
   @Override
   public double getMolarVolume() {

src/test/java/neqsim/thermo/system/SystemPrEosTest.java

@@ -31,6 +31,31 @@ public static void setUp() {
     testSystem.initProperties();
   }
 
+  /**
+   * <p>
+   * testMolarVolume.
+   * </p>
+   */
+  @Test
+  @DisplayName("test testMolarVolume calc whre unit as input")
+  public void testMolarVolume() {
+    neqsim.thermo.system.SystemInterface testSystem =
+        new neqsim.thermo.system.SystemPrEos(298.0, 10.0);
+    testSystem.addComponent("nitrogen", 0.01);
+    testSystem.addComponent("CO2", 0.01);
+    testSystem.addComponent("methane", 0.68);
+    testSystem.addComponent("ethane", 0.1);
+    testSystem.setMixingRule("classic");
+    testModel = new neqsim.thermo.ThermodynamicModelTest(testSystem);
+    ThermodynamicOperations testOps = new ThermodynamicOperations(testSystem);
+    testOps.TPflash();
+    testSystem.initProperties();
+    assertEquals(testSystem.getMolarVolume("m3/mol"),
+        testSystem.getMolarMass("kg/mol") / testSystem.getDensity("kg/m3"));
+  }
+
+
+
   /**
    * <p>
    * testTPflash2.