Engineering task and calculation objective
The PROP module is the interface to physical property determination with PROPER. Through this link, thermophysical property data for pure substances and mixtures can be transferred directly into the calculation: density, specific heat capacity, enthalpy, heat of evaporation, thermal conductivity, dynamic viscosity, Prandtl number, surface tension, coefficient of thermal expansion, thermal diffusivity, as well as real-gas quantities such as the compressibility factor, isentropic exponent, molar mass and critical data.
In process engineering, consistent physical properties are the foundation of every heat exchanger, pressure drop or safety valve calculation. Instead of copying values manually from tables, PROP retrieves them for the actual state point (pressure, temperature, composition) – for single-phase states as well as for saturated states and phase equilibria, for refrigerants, natural gas and other industrial fluids.
The practical benefit: all downstream modules calculate with the same property data, matched to the state point. This eliminates transcription errors and inconsistencies, which are a frequent source of error in equipment design when properties are entered manually.
Calculation workflow
- Select the substance or mixture: The pure substance or the mixture with its composition is selected from the PROPER property database; for mixtures, the fractions of the components are specified.
- Define the state point: Pressure and temperature (or the saturation state) define the state point for which the properties are to be determined – single-phase liquid, single-phase gaseous, or on the bubble/dew line.
- Retrieve the properties: PROPER calculates the requested quantities such as density, heat capacity, viscosity, thermal conductivity, enthalpy, heat of evaporation, surface tension, Prandtl number, compressibility factor and isentropic exponent for the selected state point.
- Transfer the values into the calculation: The determined property data are immediately and consistently available to the subsequent calculation modules – for heat transfer, pressure drop or vessel design, for example.
Input quantities
| Quantity | Symbol | Unit |
|---|---|---|
| File name | Stoffname | - |
| 1 | ϑ1 | °C |
| 2 | ϑ2 | °C |
| 1 | p1 | Pa |
| 2 | p2 | Pa |
| 1 | ρ1 | kg/m³ |
| 2 | ρ2 | kg/m³ |
| 3 | ρ1 | kg/m³ |
| 4 | ρ2 | kg/m³ |
| 1 | cp1 | J/(kg·K) |
| 2 | cp2 | J/(kg·K) |
| 3 | cp1 | J/(kg·K) |
| 4 | cp2 | J/(kg·K) |
| 1 | η1 | mPa·s |
| 2 | η2 | mPa·s |
| 3 | η1 | mPa·s |
| 4 | η2 | mPa·s |
| 1 | ν1 | m²/s |
| 2 | ν2 | m²/s |
| 3 | ν1 | m²/s |
| 4 | ν2 | m²/s |
| 1 | λ1 | W/(m·K) |
| 2 | λ2 | W/(m·K) |
| 3 | λ1 | W/(m·K) |
Calculation options
Phasengleichgewichtsmodell
No calculation of the phase equilibrium · 1 · 2 · 3 · 4 · 5 · 6 · 7 · 8 · 9 · 10 · 11
Create / load Stream file
1 · 2
Frequently asked questions
For which substances does the interface provide property data?
For the pure substances and mixtures stored in the PROPER database, including industrial gases, refrigerants, natural gas and water/steam. For mixtures, the properties are determined from the pure-component data and suitable mixing rules or equations of state; phase equilibria and vapour fractions can also be determined.
Why is the state point so important for physical properties?
Many properties depend strongly on temperature and pressure: the viscosity of liquids often changes by orders of magnitude with temperature, the density of gases almost proportionally with pressure, and near the phase boundary or the critical point all quantities change particularly steeply. Property data must therefore always be retrieved for the actual operating state, not for standard conditions.
What must be considered for two-phase states?
In the wet-steam region, quantities such as density or enthalpy are only unambiguous together with the vapour fraction. The interface then delivers the values of the saturated liquid and the saturated vapour separately; mixture quantities follow from the vapour quality or the volumetric void fraction. Heat transfer correlations usually require the individual phase values.