From 8cdf7328ea2d6ba467bbcb486fd267e153487573 Mon Sep 17 00:00:00 2001
From: Felix MARSOLLIER <fm4b8dfn@dsp1027505>
Date: Wed, 7 Sep 2022 16:45:34 +0200
Subject: [PATCH] =?UTF-8?q?Error=20correction:=20The=20reference=20in=20th?=
=?UTF-8?q?e=20function=20enthalpyOfWater=20and=20its=20derivative=20was?=
=?UTF-8?q?=200=C2=B0C=20rather=20than=2020=C2=B0C.=20That=20was=20causing?=
=?UTF-8?q?=20the=20error=20in=20the=20T=5FphX=20function?=
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---
Media/Air/MoistAir.mo | 25 +++++++++++++------------
1 file changed, 13 insertions(+), 12 deletions(-)
diff --git a/Media/Air/MoistAir.mo b/Media/Air/MoistAir.mo
index f475437..395e69d 100644
--- 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>
--
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