Added Vega EOS modell(helmholtz free energy) for helium (#1278)

* Added Vega EOS modell(helmholtz free energy) for helium

* Update Vega.java

* Ran mvn javadoc:fix

Author: victorigi99

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

@@ -2230,6 +2230,20 @@ public double[] getProperties_GERG2008() {
 
   /** {@inheritDoc} */
   @Override
+
+  public double getDensity_Vega() {
+    neqsim.thermo.util.Vega.NeqSimVega test = new neqsim.thermo.util.Vega.NeqSimVega(this);
+    return test.getDensity();
+  }
+  
+  /** {@inheritDoc} */
+  @Override
+  public double[] getProperties_Vega() {
+    neqsim.thermo.util.Vega.NeqSimVega test = new neqsim.thermo.util.Vega.NeqSimVega(this);
+    return test.propertiesVega();
+  }
+
+
   public double getDensity_Leachman(String hydrogenType) {
     neqsim.thermo.util.leachman.NeqSimLeachman test = 
       new neqsim.thermo.util.leachman.NeqSimLeachman(this, hydrogenType);
@@ -2260,18 +2274,17 @@ public double[] getProperties_Leachman(String hydrogenType) {
 
 
   /**
- * Gets the Leachman properties of a phase using the default hydrogen type ('normal').
- * This method prints a warning if no hydrogen type is specified.
- *
- * @return an array of properties of type double.
- */
+   * Gets the Leachman properties of a phase using the default hydrogen type ('normal').
+   * This method prints a warning if no hydrogen type is specified.
+   *
+   * @return an array of properties of type double.
+   */
   public double[] getProperties_Leachman() {
     // Warn the user and use the default hydrogen type
     System.out.println("No hydrogen type specified. Using default type: 'normal'.");
     return getProperties_Leachman("normal");
   }
 
-
   /** {@inheritDoc} */
   @Override
   public double getDensity_AGA8() {

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

@@ -111,11 +111,13 @@ public void init(double totalNumberOfMoles, int numberOfComponents, int initType
     setType(PhaseType.HYDRATE);
   }
 
+  /** {@inheritDoc} */
   @Override
   public MixingRulesInterface getMixingRule() {
     return null;
   }
 
+  /** {@inheritDoc} */
   @Override
   public void setMixingRuleGEModel(String name) {}
 

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

@@ -419,10 +419,10 @@ public default void initPhysicalProperties(String name) {
    */
   public double[] getProperties_GERG2008();
 
-
+ 
   /**
    * method to get Leachman density of a phase using the Leachman EoS.
-   * 
+   *
    * @param hydrogenType Supported types are 'normal', 'para', 'ortho'
    * @return density with unit kg/m3
    */
@@ -441,18 +441,37 @@ public default void initPhysicalProperties(String name) {
    * </p>
    *
    * @return an array of type double
+   * @param hydrogenType a {@link java.lang.String} object
    */
-
   public double[] getProperties_Leachman(String hydrogenType);
 
   /**
    * Overloaded method to get the Leachman properties with default hydrogen type ('normal').
    *
    * @return density with unit kg/m3
    */
-
   public double[] getProperties_Leachman();
 
+
+  
+
+    /**
+   * method to get helium density of a phase using the Vega EoS.
+   *
+   * @return density with unit kg/m3
+   */
+  public double getDensity_Vega();
+
+  /**
+   * <p>
+   * method to get helium properties of a phase using the Vega EoS.
+   * </p>
+   *
+   * @return an array of type double
+   */
+  public double[] getProperties_Vega();
+
+
   /**
    * method to get density of a phase note: does not use Peneloux volume correction.
    *
@@ -725,7 +744,7 @@ public default void initPhysicalProperties(String name) {
 
   /**
    * Normalize property <code>x</code>.
-   * 
+   *
    * <p>
    * Property <code>x</code> is the mole fraction of a component in a specific phase. Normalizing,
    * means that the sum of <code>x</code> for all Components in a phase equal 1.0.