Annex60.Media.Specialized.Water.TemperatureDependentDensity

# .Annex60.Media.Specialized.Water.TemperatureDependentDensity

Package with model for liquid water with temperature-dependent density

## Information

This medium package models liquid water.

The mass density is computed using a 3rd order polynomial, which yields the density as a function of temperature as shown in the figure below. Note, however, that computing density as a function of temperature can lead to considerably slower computing time compared to using Annex60.Media.Water in which the density is a constant. We therefore recommend to use Annex60.Media.Water for typical building energy simulations.

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. Using a constant value for the specific heat capacity allows to compute temperature from enthalpy without having to solve an implicit equation, and therefore leads to faster simulation.

Thermal conductivity is calculated as a function of temperature as shown in the figure below. The correlation used to calculate the thermal conductivity is

λ(T) = λ(298.15 K) ⋅ (-1.48445+4.12292⋅(T/298.15)-1.63866⋅(T/298.15)2),

where λ(298.15 K) = 0.6065 W/(m ⋅ K) is the adopted standard value of the thermal conductivity of water at 298.15 K and 0.1 MPa.

Dynamic viscosity is calculated as the product of density and kinematic viscosity, both temperature dependent. However, the kinematic viscosity has its own temperture dependent correlation, implemented at Annex60.Media.Specialized.Water.TemperatureDependentDensity.kinematicViscosity. Results of the kinematic viscosity as a function of temperature are shown in the figure below.

The enthalpy is computed using the convention that h=0 if T=0 °C.

#### Limitations

Phase changes are not modeled.

## Contents

Name | Description
--- | ---
FluidConstants |
ThermodynamicState | Thermodynamic state variables
BaseProperties | Base properties
density | Return the density
dynamicViscosity | Return the dynamic viscosity
specificEnthalpy | Return the specific enthalpy
enthalpyOfLiquid | Return the specific enthalpy of liquid
specificInternalEnergy | Return the specific enthalpy
specificEntropy | Return the specific entropy
specificGibbsEnergy | Return the specific Gibbs energy
specificHelmholtzEnergy | Return the specific Helmholtz energy
isentropicEnthalpy | Return the isentropic enthalpy
isobaricExpansionCoefficient | Return the isobaric expansion coefficient
isothermalCompressibility | Return the isothermal compressibility factor
density_derp_T | Return the partial derivative of density with respect to pressure at constant temperature
density_derT_p | Return the partial derivative of density with respect to temperature at constant pressure
density_derX | Return the partial derivative of density with respect to mass fractions at constant pressure and temperature
specificHeatCapacityCp | Return the specific heat capacity at constant pressure
specificHeatCapacityCv | Return the specific heat capacity at constant volume
thermalConductivity | Return the thermal conductivity
pressure | Return the pressure
temperature | Return the temperature
molarMass | Return the molar mass
setState_dTX | Return thermodynamic state from d, T, and X or Xi
setState_phX | Return the thermodynamic state as function of pressure p, specific enthalpy h and composition X or Xi
setState_pTX | Return the thermodynamic state as function of p, T and composition X or Xi
setState_psX | Return the thermodynamic state as function of p, s and composition X or Xi

## Revisions

- July 7, 2016, by Carles Ribas Tugores:
  Correct Documentation. This is for #487.
- June 6, 2015, by Michael Wetter:
  Set `AbsolutePressure(start=p_default)` and `Temperature(start=T_default)` to have to have conistent start values. See also revision notes of Annex60.Media.Water. This is for #266.
- May 1, 2015, by Michael Wetter:
  Added `Inline=true` for issue 227.
- February 25, 2015, by Michael Wetter:
  Removed `stateSelect` attribute on pressure as this caused Annex60.Examples.Tutorial.SpaceCooling.System3 to fail with the error message "differentiated if-then-else was not continuous".
- February 3, 2015, by Michael Wetter:
  Removed `stateSelect.prefer` for temperature. This is for #160.
- October 15, 2014, by Michael Wetter:
  Renamed from `Annex60.Media.Water` to `Annex60.Media.Water.Detailed` to allow addition of `Annex60.Media.Water.Simple`.
- September 12, 2014, by Michael Wetter:
  Set `T(start=T_default)` and `p(start=p_default)` in the `ThermodynamicState` record. Setting the start value for `T` is required to avoid an error due to conflicting start values when checking Annex60.Examples.VAVReheat.ClosedLoop in pedantic mode.
- December 18, 2013, by Michael Wetter:
  First implementation.

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