Description: "Package with model for liquid water with constant density"

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## Buildings.Media.Water

Package with model for liquid water with constant density

### 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 Buildings.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.

Extends from Modelica.Media.Water.ConstantPropertyLiquidWater (Water: Simple liquid water medium (incompressible, constant data)), Modelica.Icons.Package (Icon for standard packages).

### Package Content

Name | Description
--- | ---
ThermodynamicState | Thermodynamic state variables
BaseProperties | Base properties
enthalpyOfLiquid | Return the specific enthalpy of liquid
Inherited
simpleWaterConstants |
cp_const | Constant specific heat capacity at constant pressure
cv_const | Constant specific heat capacity at constant volume
d_const | Constant density
eta_const | Constant dynamic viscosity
lambda_const | Constant thermal conductivity
a_const | Constant velocity of sound
T_min | Minimum temperature valid for medium model
T_max | Maximum temperature valid for medium model
T0=reference_T | Zero enthalpy temperature
MM_const | Molar mass
fluidConstants | Fluid constants
setState_pTX | Return thermodynamic state from p, T, and X or Xi
setState_phX | Return thermodynamic state from p, h, and X or Xi
setState_psX | Return thermodynamic state from p, s, and X or Xi
setState_dTX | Return thermodynamic state from d, T, and X or Xi
setSmoothState | Return thermodynamic state so that it smoothly approximates: if x > 0 then state_a else state_b
dynamicViscosity | Return dynamic viscosity
thermalConductivity | Return thermal conductivity
pressure | Return pressure
temperature | Return temperature
density | Return density
specificEnthalpy | Return specific enthalpy
specificHeatCapacityCp | Return specific heat capacity at constant pressure
specificHeatCapacityCv | Return specific heat capacity at constant volume
isentropicExponent | Return isentropic exponent
velocityOfSound | Return velocity of sound
specificEnthalpy_pTX | Return specific enthalpy from p, T, and X or Xi
temperature_phX | Return temperature from p, h, and X or Xi
density_phX | Return density from p, h, and X or Xi
specificInternalEnergy | Return specific internal energy
specificEntropy | Return specific entropy
specificGibbsEnergy | Return specific Gibbs energy
specificHelmholtzEnergy | Return specific Helmholtz energy
isentropicEnthalpy | Return isentropic enthalpy
isobaricExpansionCoefficient | Returns overall the isobaric expansion coefficient beta
isothermalCompressibility | Returns overall the isothermal compressibility factor
density_derp_T | Returns the partial derivative of density with respect to pressure at constant temperature
density_derT_p | Returns the partial derivative of density with respect to temperature at constant pressure
density_derX | Returns the partial derivative of density with respect to mass fractions at constant pressure and temperature
molarMass | Return the molar mass of the medium
setState_pT | Return thermodynamic state from p and T
setState_ph | Return thermodynamic state from p and h
setState_ps | Return thermodynamic state from p and s
setState_dT | Return thermodynamic state from d and T
density_ph | Return density from p and h
temperature_ph | Return temperature from p and h
pressure_dT | Return pressure from d and T
specificEnthalpy_dT | Return specific enthalpy from d and T
specificEnthalpy_ps | Return specific enthalpy from p and s
temperature_ps | Return temperature from p and s
density_ps | Return density from p and s
specificEnthalpy_pT | Return specific enthalpy from p and T
density_pT | Return density from p and T
ThermoStates | Enumeration type for independent variables
mediumName="unusablePartialMedium" | Name of the medium
substanceNames={mediumName} | Names of the mixture substances. Set substanceNames={mediumName} if only one substance.
extraPropertiesNames=fill("", 0) | Names of the additional (extra) transported properties. Set extraPropertiesNames=fill("",0) if unused
singleState | = true, if u and d are not a function of pressure
reducedX=true | = true if medium contains the equation sum(X) = 1.0; set reducedX=true if only one substance (see docu for details)
fixedX=false | = true if medium contains the equation X = reference_X
reference_p=101325 | Reference pressure of Medium: default 1 atmosphere
reference_T=298.15 | Reference temperature of Medium: default 25 deg Celsius
reference_X=fill(1/nX, nX) | Default mass fractions of medium
p_default=101325 | Default value for pressure of medium (for initialization)
T_default=Modelica.SIunits.Conversions.from_degC(20) | Default value for temperature of medium (for initialization)
h_default=specificEnthalpy_pTX(p_default, T_default, X_default) | Default value for specific enthalpy of medium (for initialization)
X_default=reference_X | Default value for mass fractions of medium (for initialization)
nS=size(substanceNames, 1) | Number of substances
nX=nS | Number of mass fractions
nXi=if fixedX then 0 else if reducedX then nS - 1 else nS | Number of structurally independent mass fractions (see docu for details)
nC=size(extraPropertiesNames, 1) | Number of extra (outside of standard mass-balance) transported properties
C_nominal=1.0e-6*ones(nC) | Default for the nominal values for the extra properties
FluidConstants | Critical, triple, molecular and other standard data of fluid
prandtlNumber | Return the Prandtl number
heatCapacity_cp | Alias for deprecated name
heatCapacity_cv | Alias for deprecated name
beta | Alias for isobaricExpansionCoefficient for user convenience
kappa | Alias of isothermalCompressibility for user convenience
density_derp_h | Return density derivative w.r.t. pressure at const specific enthalpy
density_derh_p | Return density derivative w.r.t. specific enthalpy at constant pressure
specificEntropy_pTX | Return specific enthalpy from p, T, and X or Xi
density_pTX | Return density from p, T, and X or Xi
temperature_psX | Return temperature from p,s, and X or Xi
density_psX | Return density from p, s, and X or Xi
specificEnthalpy_psX | Return specific enthalpy from p, s, and X or Xi
MassFlowRate | Type for mass flow rate with medium specific attributes
AbsolutePressure | Type for absolute pressure with medium specific attributes
Density | Type for density with medium specific attributes
DynamicViscosity | Type for dynamic viscosity with medium specific attributes
EnthalpyFlowRate | Type for enthalpy flow rate with medium specific attributes
MassFraction | Type for mass fraction with medium specific attributes
MoleFraction | Type for mole fraction with medium specific attributes
MolarMass | Type for molar mass with medium specific attributes
MolarVolume | Type for molar volume with medium specific attributes
IsentropicExponent | Type for isentropic exponent with medium specific attributes
SpecificEnergy | Type for specific energy with medium specific attributes
SpecificInternalEnergy | Type for specific internal energy with medium specific attributes
SpecificEnthalpy | Type for specific enthalpy with medium specific attributes
SpecificEntropy | Type for specific entropy with medium specific attributes
SpecificHeatCapacity | Type for specific heat capacity with medium specific attributes
SurfaceTension | Type for surface tension with medium specific attributes
Temperature | Type for temperature with medium specific attributes
ThermalConductivity | Type for thermal conductivity with medium specific attributes
PrandtlNumber | Type for Prandtl number with medium specific attributes
VelocityOfSound | Type for velocity of sound with medium specific attributes
ExtraProperty | Type for unspecified, mass-specific property transported by flow
CumulativeExtraProperty | Type for conserved integral of unspecified, mass specific property
ExtraPropertyFlowRate | Type for flow rate of unspecified, mass-specific property
IsobaricExpansionCoefficient | Type for isobaric expansion coefficient with medium specific attributes
DipoleMoment | Type for dipole moment with medium specific attributes
DerDensityByPressure | Type for partial derivative of density with respect to pressure with medium specific attributes
DerDensityByEnthalpy | Type for partial derivative of density with respect to enthalpy with medium specific attributes
DerEnthalpyByPressure | Type for partial derivative of enthalpy with respect to pressure with medium specific attributes
DerDensityByTemperature | Type for partial derivative of density with respect to temperature with medium specific attributes
DerTemperatureByPressure | Type for partial derivative of temperature with respect to pressure with medium specific attributes
SaturationProperties | Saturation properties of two phase medium
FluidLimits | Validity limits for fluid model
FixedPhase | Phase of the fluid: 1 for 1-phase, 2 for two-phase, 0 for not known, e.g., interactive use
Basic | The most basic version of a record used in several degrees of detail
IdealGas | The ideal gas version of a record used in several degrees of detail
TwoPhase | The two phase fluid version of a record used in several degrees of detail

## Buildings.Media.Water.ThermodynamicState

Thermodynamic state variables

### Information

Extends from (Thermodynamic state).

### Modelica definition

record extends ThermodynamicState( T(start=T_default), p(start=p_default)) "Thermodynamic state variables" end ThermodynamicState;

## Buildings.Media.Water.BaseProperties

Base properties

### Information

This base properties model is identical to Modelica.Media.Water.ConstantPropertyLiquidWater, except that the equation `u = cv_const*(T - reference_T)` has been replaced by `u=h` because `cp_const=cv_const`.

### Parameters

Type | Name | Default | Description
--- | --- | --- | ---
Advanced
Boolean | preferredMediumStates | true | = true if StateSelect.prefer shall be used for the independent property variables of the medium

### Modelica definition

redeclare model BaseProperties "Base properties" Modelica.SIunits.Temperature T "Temperature of medium"; InputAbsolutePressure p "Absolute pressure of medium"; InputMassFraction[nXi] Xi=fill(0, 0) "Structurally independent mass fractions"; InputSpecificEnthalpy h "Specific enthalpy of medium"; Modelica.SIunits.SpecificInternalEnergy u "Specific internal energy of medium"; Modelica.SIunits.Density d=d_const "Density of medium"; Modelica.SIunits.MassFraction[nX] X={1} "Mass fractions (= (component mass)/total mass m_i/m)"; final Modelica.SIunits.SpecificHeatCapacity R=0 "Gas constant (of mixture if applicable)"; final Modelica.SIunits.MolarMass MM=MM_const "Molar mass (of mixture or single fluid)"; ThermodynamicState state "Thermodynamic state record for optional functions"; parameter Boolean preferredMediumStates=true "= true if StateSelect.prefer shall be used for the independent property variables of the medium"; final parameter Boolean standardOrderComponents=true "If true, and reducedX = true, the last element of X will be computed from the other ones"; Modelica.SIunits.Conversions.NonSIunits.Temperature_degC T_degC= Modelica.SIunits.Conversions.to_degC(T) "Temperature of medium in [degC]"; Modelica.SIunits.Conversions.NonSIunits.Pressure_bar p_bar= Modelica.SIunits.Conversions.to_bar(p) "Absolute pressure of medium in [bar]"; // Local connector definition, used for equation balancing check connector InputAbsolutePressure = input Modelica.SIunits.AbsolutePressure "Pressure as input signal connector"; connector InputSpecificEnthalpy = input Modelica.SIunits.SpecificEnthalpy "Specific enthalpy as input signal connector"; connector InputMassFraction = input Modelica.SIunits.MassFraction "Mass fraction as input signal connector"; equation assert(T >= T_min and T <= T_max, " Temperature T (= " + String(T) + " K) is not in the allowed range (" + String(T_min) + " K <= T <= " + String(T_max) + " K) required from medium model \"" + mediumName + "\". "); h = cp_const*(T-reference_T); u = h; state.T = T; state.p = p; end BaseProperties;

## Buildings.Media.Water.enthalpyOfLiquid

Return the specific enthalpy of liquid

### Information

Enthalpy of the water.

Extends from Modelica.Icons.Function (Icon for functions).

### Inputs

Type | Name | Default | Description
--- | --- | --- | ---
Temperature | T |  | Temperature [K]

### Outputs

Type | Name | Description
--- | --- | ---
SpecificEnthalpy | h | Specific enthalpy [J/kg]

### Modelica definition

function enthalpyOfLiquid "Return the specific enthalpy of liquid" extends Modelica.Icons.Function; input Modelica.SIunits.Temperature T "Temperature"; output Modelica.SIunits.SpecificEnthalpy h "Specific enthalpy"; algorithm h := cp_const*(T-reference_T); end enthalpyOfLiquid;

## Buildings.Media.Water.BaseProperties.InputAbsolutePressure

Pressure as input signal connector

### Modelica definition

connector InputAbsolutePressure = input Modelica.SIunits.AbsolutePressure "Pressure as input signal connector";

## Buildings.Media.Water.BaseProperties.InputMassFraction

Mass fraction as input signal connector

### Modelica definition

connector InputMassFraction = input Modelica.SIunits.MassFraction "Mass fraction as input signal connector";

## Buildings.Media.Water.BaseProperties.InputSpecificEnthalpy

Specific enthalpy as input signal connector

### Modelica definition

connector InputSpecificEnthalpy = input Modelica.SIunits.SpecificEnthalpy "Specific enthalpy as input signal connector";