BuildSysPro.IBPSA.Media.Steam

# .BuildSysPro.IBPSA.Media.Steam

Package with model for pure steam water vapor

## Information

This medium package models water vapor (pure steam, region 2, quality=1).

Thermodynamic properties are calculated primarily in terms of pressure and temperature. For thermodynamic property functions, the IAPWS-IF97 formulations are adapted, and approximate relationships are provided for commonly used functions to improve computational efficiency and provide backward compatability.

Detailed functions from Modelica.Media.Water.WaterIF97_R2pT are generally used, except for IBPSA.Media.Steam.specificEnthalpy and IBPSA.Media.Steam.specificEntropy (both "forward" functions), as well as their "backward" inverse functions IBPSA.Media.Steam.temperature_ph and IBPSA.Media.Steam.temperature_ps, which are numerically consistent with the forward functions. The following modifications were made relative to the Modelica.Media.Water.WaterIF97_R2pT medium package:

1. Analytic expressions for the derivatives are provided for all thermodynamic property functions.
2. The implementation is generally simpler in order to increase the likelihood of more efficient simulations.

#### Limitations

- The valid temperature range is 100°C ≤ T ≤ 160°C, and the valid pressure range is 100 kPa ≤ p ≤ 550 kPa.
- When phase change is required, this model is to be used in combination with IBPSA.Media.Water for the liquid phase (quality=0). Please note that the maximum temperature for liquid water is `T_max=130°C`. This is suitable for real-world condensate return and boiler feedwater systems, which are typically vented to the atmosphere with steam contained via steam traps (thus, `T_max=100°C` for the condensate or feedwater in properly functioning systems).

#### Applications

This model is intended for first generation district heating systems and other steam heating processes involving low and medium pressure steam.

#### References

W. Wagner et al., “The IAPWS industrial formulation 1997 for the thermodynamic properties of water and steam,” J. Eng. Gas Turbines Power, vol. 122, no. 1, pp. 150–180, 2000.

## Contents

Name | Description
--- | ---
ThermodynamicState | Thermodynamic state variables
BaseProperties | Base properties (p, d, T, h, u, R, MM) of water
density | Returns density
dynamicViscosity | Return dynamic viscosity
molarMass | Return the molar mass of the medium
pressure | Return pressure
saturationPressure | Return saturation pressure of condensing fluid
saturationTemperature | Return saturation temperature
specificEnthalpy | Returns specific enthalpy
specificEntropy | Return specific entropy
specificInternalEnergy | Return specific internal energy
specificHeatCapacityCp | Specific heat capacity at constant pressure
specificHeatCapacityCv | Specific heat capacity at constant volume
specificGibbsEnergy | Specific Gibbs energy
specificHelmholtzEnergy | Specific Helmholtz energy
setState_dTX | Return the thermodynamic state as function of d and T
setState_pTX | Return the thermodynamic state as function of p and T
setState_phX | Return the thermodynamic state as function of p and h
setState_psX | Return the thermodynamic state as function of p and s
temperature | Return temperature
thermalConductivity | Return thermal conductivity
density_derh_p | Density derivative by specific enthalpy
density_derp_h | Density derivative by pressure
isentropicExponent | Return isentropic exponent
isothermalCompressibility | Isothermal compressibility of water
isobaricExpansionCoefficient | Isobaric expansion coefficient of water
isentropicEnthalpy | Isentropic enthalpy

## Revisions

- April 13, 2021, by Kathryn Hinkelman:
  Changed pressure from constant to variable and reduced applicable pressure-temperature range to improve accuracy of polynomial approximations.
- October 30, 2020, by Kathryn Hinkelman:
  Complete new reimplementation to eliminate numerical inefficiencies and improve accuracy of property function calculations.

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