packageWater
Package with model for liquid water with constant density
Extends from Modelica.Media.Water.ConstantPropertyLiquidWater (Water: Simple liquid water medium (incompressible, constant data)), Modelica.Icons.Package (Icon for standard packages).
Information
This medium package models liquid water.
The mass density is computed using a constant value of 995.586 kg/s. For a medium model in which the density is a function of temperature, use IBPSA.Media.Specialized.Water.TemperatureDependentDensity which may have considerably higher computing time.
For the specific heat capacities at constant pressure and at constant volume, a constant value of 4184 J/(kg K), which corresponds to 20°C is used. The figure below shows the relative error of the specific heat capacity that is introduced by this simplification.
The enthalpy is computed using the convention that h=0 if T=0 °C.
Limitations
Density, specific heat capacity, thermal conductivity and viscosity are constant. Water is modeled as an incompressible liquid. There are no phase changes.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Modelica.Media.Interfaces.Types.Basic.FluidConstants | simpleWaterConstants (from ConstantPropertyLiquidWater) | ||
| Modelica.Media.Interfaces.Choices.IndependentVariables | ThermoStates (from PartialMedium) | Enumeration type for independent variables | |
| String | mediumName (from PartialMedium) | "unusablePartialMedium" | Name of the medium |
| String[:] | substanceNames (from PartialMedium) | {mediumName} | Names of the mixture substances. Set substanceNames={mediumName} if only one substance. |
| String[:] | extraPropertiesNames (from PartialMedium) | fill("", 0) | Names of the additional (extra) transported properties. Set extraPropertiesNames=fill("",0) if unused |
| Boolean | singleState (from PartialMedium) | = true, if u and d are not a function of pressure | |
| Boolean | reducedX (from PartialMedium) | true | = true, if medium contains the equation sum(X) = 1.0; set reducedX=true, if only one substance (see docu for details) |
| Boolean | fixedX (from PartialMedium) | false | = true, if medium contains the equation X = reference_X |
| AbsolutePressure | reference_p (from PartialMedium) | 101325 | Reference pressure of Medium: default 1 atmosphere |
| Temperature | reference_T (from PartialMedium) | 298.15 | Reference temperature of Medium: default 25 deg Celsius |
| MassFraction[nX] | reference_X (from PartialMedium) | fill(1/nX, nX) | Default mass fractions of medium |
| AbsolutePressure | p_default (from PartialMedium) | 101325 | Default value for pressure of medium (for initialization) |
| Temperature | T_default (from PartialMedium) | Modelica.Units.Conversions.from_degC(20) | Default value for temperature of medium (for initialization) |
| SpecificEnthalpy | h_default (from PartialMedium) | specificEnthalpy_pTX(p_default, T_default, X_default) | Default value for specific enthalpy of medium (for initialization) |
| MassFraction[nX] | X_default (from PartialMedium) | reference_X | Default value for mass fractions of medium (for initialization) |
| ExtraProperty[nC] | C_default (from PartialMedium) | fill(0, nC) | Default value for trace substances of medium (for initialization) |
| Integer | nS (from PartialMedium) | size(substanceNames, 1) | Number of substances |
| Integer | nX (from PartialMedium) | nS | Number of mass fractions |
| Integer | nXi (from PartialMedium) | if fixedX then 0 else if reducedX then nS - 1 else nS | Number of structurally independent mass fractions (see docu for details) |
| Integer | nC (from PartialMedium) | size(extraPropertiesNames, 1) | Number of extra (outside of standard mass-balance) transported properties |
| Real[nC] | C_nominal (from PartialMedium) | 1.0e-6*ones(nC) | Default for the nominal values for the extra properties |
| SpecificHeatCapacity | cp_const (from PartialSimpleMedium) | Constant specific heat capacity at constant pressure | |
| SpecificHeatCapacity | cv_const (from PartialSimpleMedium) | Constant specific heat capacity at constant volume | |
| Density | d_const (from PartialSimpleMedium) | Constant density | |
| DynamicViscosity | eta_const (from PartialSimpleMedium) | Constant dynamic viscosity | |
| ThermalConductivity | lambda_const (from PartialSimpleMedium) | Constant thermal conductivity | |
| VelocityOfSound | a_const (from PartialSimpleMedium) | Constant velocity of sound | |
| Temperature | T_min (from PartialSimpleMedium) | Minimum temperature valid for medium model | |
| Temperature | T_max (from PartialSimpleMedium) | Maximum temperature valid for medium model | |
| Temperature | T0 (from PartialSimpleMedium) | reference_T | Zero enthalpy temperature |
| MolarMass | MM_const (from PartialSimpleMedium) | Molar mass | |
| FluidConstants | fluidConstants (from PartialSimpleMedium) | Fluid constants |
Contents
| Name | Description |
|---|---|
| BaseProperties | Base properties |
 enthalpyOfLiquid | Return the specific enthalpy of liquid |
Revisions
-
June 6, 2015, by Michael Wetter:
SetAbsolutePressure(start=p_default)to avoid a translation error if IBPSA.Fluid.Sources.Examples.TraceSubstancesFlowSource (if used with water instead of air) is translated in pedantic mode in Dymola 2016. The reason is that pressures useMedium.p_defaultas start values, but Modelica.Media.Interfaces.Types sets a default value of 1E-5. A similar change has been done for pressure and density. This fixes #266. -
June 6, 2015, by Michael Wetter:
Changed type ofBaseProperties.TfromModelica.SIunits.TemperaturetoTemperature. Otherwise, it has a different start value thanMedium.T, which causes an error if IBPSA.Media.Examples.WaterProperties is translated in pedantic mode. This fixes #266. -
June 5, 2015, by Michael Wetter:
AddedstateSelectattribute inBaseProperties.Tto allow correct use ofpreferredMediumStateas described in Modelica.Media.Interfaces.PartialMedium, and setpreferredMediumState=falseto keep the same states as were used before. This is for #260. -
June 5, 2015, by Michael Wetter:
RemovedThermodynamicStatedeclaration as this lead to the error "Attempting to redeclare record ThermodynamicState when the original was not replaceable." in Dymola 2016 using the pedantic model check. -
May 1, 2015, by Michael Wetter:
AddedInline=truefor issue 227. -
February 25, 2015, by Michael Wetter:
RemovedstateSelectattribute on pressure as this caused IBPSA.Examples.Tutorial.SpaceCooling.System3 to fail with the error message "differentiated if-then-else was not continuous". -
October 15, 2014, by Michael Wetter:
Reimplemented media based on 446aa83. -
November 15, 2013, by Michael Wetter:
Complete new reimplementation because the previous version had the option to add a compressibility to the medium, which has never been used.