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Water Settings

Simulation settings for Water

  

 

Description

Parameters

See Also

Description

By placing the Water Settings component, you can define the simulation settings for Water. All components in the Water component library have Water simulation settings parameter. You need to specify which Water Settings component is assigned with the parameter by name.

For example, if you place this Water Settings in the model workspace, the name WaterSettings1 is assigned to it as default. Then, after placing Water.Basic.WaterVolume, you need to check the value of Water simulation settings. As default, the value is WaterSettings1, so the simulation settings is defined by WaterSettings1. If you want to change the associated Water Setting component, you can specify it by name.

This framework allows you to define and change the simulation settings for multiple components simultaneously.

 

Fidelity of properties

Three types of fidelity can be used in the current version of the Heat Transfer Library. There is a trade-off between the capability of the physical phenomena expression and the simulation cost. Thus, you need to specify it with your purpose of simulation.

 

• 

Constant

If you use this mode, the properties is assigned with the following constants.

 

Specific heat capacity at the constant pressure c__p JkgK :

c__p=4184

Molar mass MM kgmol :

MM=0.018015268

Gas constant R__gas JkgK :

R__gas=RMM

(*) R is Universal gas constant, and the value is 8.3144598JmolK

Specific heat capacity at the constant volume c__v JkgK :

c__v=4184

Dynamic viscosity μ Pa s :

μ=0.001

Thermal conductivity k WmK :

k=0.598

And, the specific enthalpy hflow is calculated with the following equation, and which is called as Function__hflow :

hflow=c__pT+hflow__off

hflow__off=1142798.49977

(*) The offset value of specific enthalpy is defined to be the same value as the other types of property at 273.15[K] and 101325[Pa]

 

• 

Liquid Water (Lookup table of IAPWS/IF97)

If you use this mode, the properties is assigned with the following equations and constants. And, Look Up Tables (LUT) are generated with IAPWS/IF97.

 

Specific heat capacity at the constant pressure c__p JkgK :

c__p=LUT__cpp,T

Molar mass MM kgmol :

MM=0.0289651159

Gas constant R__gas JkgK :

R__gas=RMM

(*) R is Universal gas constant, and the value is 8.3144598JmolK

Specific heat capacity at the constant volume c__v JkgK :

c__v=LUT__cvp,T

Dynamic viscosity μ Pa s :

μ=LUT__μp,T

Thermal conductivity k WmK :

k=LUT__kp,T

Specific enthalpy hflow Jkg :

hflow=LUT__hflowp,T

And, Density ρ kgm3 :

ρ=LUT__ρp,T

• 

IAPWS/IF97 standard

If you use this mode, the properties is calculated with Modelica.Media.Water package which is about IAPWS/IF97.

Specific heat capacity at the constant pressure c__p JkgK :

c__p=Function__cpp,T=`Modelica.Media.Water.IF97_Utilities.cp_pT`

Molar mass MM kgmol :

MM=0.0289651159

Gas constant R__gas JkgK :

R__gas=RMM

(*) R is Universal gas constant, and the value is 8.3144598JmolK

Specific heat capacity at the constant volume c__v JkgK :

c__v=Function__cvp,T=`Modelica.Media.Water.IF97_Utilities.cv_pT`

Dynamic viscosity μ Pa s :

μ=Function__μρ,T,p=`Modelica.Media.Water.IF97_Utilities.BaseIF97.Transport.visc_dTp`

Thermal conductivity k WmK :

k=Function__kρ,T,p=`Modelica.Media.Water.IF97_Utilities.BaseIF97.Transport.cond_dTp`

Specific enthalpy hflow Jkg :

hflow=Function__hflowp,T=`Modelica.Media.Water.IF97_Utilities.h_pT`

And, Density ρ kgm3 :

ρ=Function__ρp,T=`Modelica.Media.Water.IF97_Utilities.rho_pT`

 

To check the details of the package and view the original documentation, which includes author and copyright information, click here.

(*) Warning : This mode is only available with Static mode of Dynamics of mass in this current version.  

Dynamics of mass

You can simulate model with Water components in Static mass flow mode and Dynamic mass flow mode. There is a trade-off between the capability of the physical phenomena expression and the simulation cost. Thus, you need to specify it with your purpose of simulation.

 

The following model is one of the simplest Water simulation model. At both sides of edge, there are Water.Boundaries.WaterBoundary components to define the boundary conditions. And, Water.Basic.WaterVolume is placed at the center of the model, which is for Mass and Energy conservation calculation. The last pieces are Water.Basic.WaterFlow which is placed at between WaterBoundary and WaterVolume. Pressure difference and Mass flow rate will be calculated in them.

With this model, the behavior of two mode is explained in below.

 

• 

Static mode

If you select Static mode, Mass flow rate will be defined with

mflow1=mflow0

Then, the pressure difference is calculated from

dp=Functionmflow1

(*) In this library, you can select several functions, like Linear type and Darcy-Weisbach equation.

Finally, p1 is obtained from

p1=p0dp

Thus, Mass flow rate is defined by the boundary condition. And by using Water.Basic.WaterValve and Pump, you can control the value of it.

 

• 

Dynamic mode

If you select Dynamic mode, the Mass flow rate condition mflow0 is not used. In Water.Basic.WaterVolume, Pressure will be calculated with Mass and Energy conservation law. So, the pressure difference is obtained from

dp=p0p1

Mass flow rate is calculated from

mflow1=Functiondp

(*) In this library, you can select several functions, like Linear type and Darcy-Weisbach equation.

In this mode, the Mass flow rate is dynamically changed based on the pressure balance calculation.

 

References

[1] : McBride B.J., Zehe M.J., and Gordon S. (2002): NASA Glenn Coefficients for Calculating Thermodynamic Properties of Individual Species. NASA report TP-2002-211556

 

Parameters

Symbol

Default

Units

Description

Modelica ID

Fidelity ofproperties

Liquid WaterLookup table of IAPWS /IF97

Select Fidelity of properties

  Constant :

      Use constants for each property.

  Liquid Water (Lookup table of IAPWS/IF97) :

      Properties are calculated with Lookup tables which are
      generated with IAPWS/IF97, and only for Liquid phase.
      (Temperature range : from 273.16 K to 500 K)
      (Pressure range : from 5000 Pa to 50 MPa)

  IAPWS/IF97 standard :

      Properties are calculated with IAPWS/IF97. Media.Water
      in Modelica Standard Library is the same as
      IAPWS/IF97.
      If you use this option, call the library for properties.
      (*) This is only available with Static mode of Dynamics
      of mass in this current version of library

Fidelity

Dynamics ofmass

Dynamic

Select Dynamics of Mass flow rate

  Static :

     Mass flow rate is static. Pressure drop are calculated at

     at each elements of pressure losses.

  Dynamic :

     Mass flow rate is calculated from pressure difference at

     each elements of pressure losses.

Mass Dynamics

See Also

Heat Transfer Library Overview

Water Overview