Error correction: The reference in the function enthalpyOfWater and its...

Error correction: The reference in the function enthalpyOfWater and its derivative was 0°C rather than 20°C. That was causing the error in the T_phX function

Error correction: The reference in the function enthalpyOfWater and its...
8cdf7328 · Felix MARSOLLIER · a3e1e123 · 8cdf7328
Commit 8cdf7328 authored 2 years ago by Felix MARSOLLIER
--- a/Media/Air/MoistAir.mo
+++ b/Media/Air/MoistAir.mo
@@ -624,7 +624,7 @@ Saturation pressure of water in the liquid and the solid region is computed usin
 /*simple model assuming constant properties:
    heat capacity of solid water: 2050 J/kg
    enthalpy of fusion (liquid=>solid): 333000 J/kg*/
-    h := Utilities.spliceFunction(water.cp * (T - 273.15), cp_ice * (T - 273.15) - 333000, T - 273.16, 0.1);
+    h := Utilities.spliceFunction(water.cp * (T - reference_T), ice.cp * (T - reference_T) - ice.h_sl, T - 273.16, 0.1);
    annotation(
      derivative = enthalpyOfWater_der,
      Documentation(info = "<html>
@@ -649,7 +649,7 @@ Saturation pressure of water in the liquid and the solid region is computed usin
    heat capacity of solid water: 2050 J/kg
    enthalpy of fusion (liquid=>solid): 333000 J/kg*/
 //h:=Utilities.spliceFunction(water.cp*(T-273.15),2050*(T-273.15)-333000,T-273.16,0.1);
-    dh := Utilities.spliceFunction_der(water.cp * (T - 273.15), cp_ice * (T - 273.15) - 333000, T - 273.16, 0.1, water.cp * dT, cp_ice * dT, dT, 0);
+    dh := Utilities.spliceFunction_der(water.cp * (T - reference_T), ice.cp * (T - reference_T) - ice.h_sl, T - 273.16, 0.1, water.cp * dT, ice.cp * dT, dT, 0);
    annotation(
      Documentation(info = "<html>
  Derivative function for <a href=\"modelica://Modelica.Media.Air.MoistAir.enthalpyOfWater\">enthalpyOfWater</a>.
@@ -688,30 +688,31 @@ Saturation pressure of water in the liquid and the solid region is computed usin
  end temperature;

  function T_phX "Return temperature as a function of pressure p, specific enthalpy h and composition X"
-    extends Modelica.Icons.UnderConstruction;
    input AbsolutePressure p "Pressure";
    input SpecificEnthalpy h "Specific enthalpy";
    input MassFraction[:] X "Mass fractions of composition";
    output Temperature T "Temperature";
+    
  protected
    SI.MoleFraction Y[2] "Mole fraction of species in the medium";
    SI.MassFraction X_liq "Mass fraction of liquid";
    SI.Temperature T_sat "Steam saturation temperature at given steam pressure";
-    SI.MassFraction X_steam "Mass fraction of steam in medium";
+    SI.MassFraction X_steam "Mass fraction of steam in medium";  
    Integer i;
+    
  algorithm
    i := 0;
-//h = X_air*dryair.cp*(T_sat-T_ref)+X_steam*(steam.cp*(T_sat-T_ref)+h_lv)+(1-X_air-X_steam)*water.cp*(T_sat-T_ref)
+  /* specific enthalpy formula is assumed to be
+  h = X_air*dryair.cp*(T_sat-T_ref)+X_steam*(steam.cp*(T_sat-T_ref)+h_lv)+(1-X_air-X_steam)*water.cp*(T_sat-T_ref) */
    T := (h - X[Water] * steam.h_lv) / (X[Air] * dryair.cp + X[Water] * steam.cp) + reference_T;
    Y := massToMoleFractions(X = X, MMX = MMX);
    T_sat := Modelica.Media.Water.IF97_Utilities.BaseIF97.Basic.tsat(p * Y[Water]);
-//Modelica.Utilities.Streams.print("T_sat = "+String(T_sat)+", i="+String(i)) ;
    if T < T_sat then
      while abs((T - T_sat) / T_sat) > 1e-5 loop
        T := T_sat;
-        X_steam := (h - (X[Air] * (dryair.cp - water.cp) + water.cp) * (T - reference_T)) / ((steam.cp - water.cp) * (T - reference_T) + steam.h_lv);
+        X_steam := ( h - (T - reference_T) * (X[Water] * water.cp + X[Air] * dryair.cp) ) / ( steam.h_lv + (steam.cp - water.cp) * (T - reference_T) );
        X_liq := X[Water] - X_steam;
-        Y := massToMoleFractions(X = {X_steam / (1 - X_liq), (1 - X_steam) / (1 - X_liq)}, MMX = MMX);
+        Y := massToMoleFractions(X = {X_steam/(1 - X_liq), 1-X_steam/(1 - X_liq) }, MMX = MMX);
        T_sat := Modelica.Media.Water.IF97_Utilities.BaseIF97.Basic.tsat(p * Y[Water]);
        i := i + 1;
      end while;
@@ -720,10 +721,10 @@ Saturation pressure of water in the liquid and the solid region is computed usin
      X_steam := X[Water];
      X_liq := 0.0;
    end if;
-/* liquid water*/
-//Modelica.Utilities.Streams.print("T_sat = "+String(T_sat)+", X_steam = "+String(X_steam)+", X_liq = "+String(X_liq)) ;
-//Modelica.Utilities.Streams.print("sum_X = "+String((X_steam + X[Air])/(1-X_liq))) ;
-//Modelica.Utilities.Streams.print("i = "+String(i)) ;
+  
+    //The region of solid water is not allowed
+    assert(T > 273.16, "The solid region for water in the T_phX function is not allowed", level = AssertionLevel.error) ;
+  //Modelica.Utilities.Streams.print("i = "+String(i)) ;
    annotation(
      Documentation(info = "<html>
      <p>