Measurement & Precise Equation of State Service

LTP is able to offer complete service chain covering measurement, correlation and software implementation of fluid properties both of pure compound, constant composition blend, or mixture with variable composition using different models (Equation of State or simpler correlation models).

tl_files/images/EOS_Meas.jpg tl_files/images/EOS_EOS.jpg  tl_files/images/DSTP3_PVT.gif


For a supplied (or commercially available) fluid sample, defined pure component or mixture we are able to provide the thermodynamic property engine DynaSol ThermoProp as dynamic link library with an Excel add-in as user interface. This software allows you to calculate various properties (depending on the used model), generate tables and to integrate the calculation methods in your own software applications. A multi-parameter Helmholtz type Equation of State (HEOS) is correlated to high accuracy experimental (and/or literature) data and allows the consistent calculation of the complete thermodynamic property surface. For binary mixtures interaction parameters for HEOS can be fitted using binary data.
Alternatively the correlated multi-parameter Equation of State and binary interaction parameters can be exported to the widely used software NIST REFPROP.


Measurement of fluid properties

The required and possible properties (from experiments and/or literature) for correlation:

  • Critical point
  • Vapor pressures (10+ data points)
  • Specific heat capacity (10+ data points)
  • For the ideal gas part: Ideal gas heat capacities (from literature, prediction, or customer data)
  • PVT data in the liquid, supercritical and vapor phase (50+ data points)
  • PVT data of binary mixtures (only for binary interaction parameter fitting)
  • VLE data of binary mixtures (only for binary interaction parameter fitting)
  • Excess enthalpy data of binary mixtures (only for binary interaction parameter fitting)

These (except ideal gas heat capacities) and some additional experimental properties can be measured at LTP. 


Correlation of fluid properties

Accurate Equations of State and binary interaction parameters in the Helmholtz formulation:

  • 12 parameter Span-Wagner EoS or Lemmon-Ihmels EoS
  • 14 parameter Sun-Ely EoS
  • 22 parameter Lemmon EoS
  • and several similar EoS (up to 32 parameters)
  • Binary interaction parameters for different mixture models (also for multi-component calculations)


Software implementation of fluid properties

Consistent calculation of following fluid properties:

  • Temperature
  • Pressure
  • Volume / density 
  • Vapor pressure
  • Heat of vaporization
  • Enthalpy
  • Entropy 
  • Energy (Gibbs, Helmholtz, and internal) 
  • Internal pressure (thermodynamic EoS)
  • Heat capacity (isobaric and isochoric)
  • Speed of sound
  • Fugacity
  • Fugacity coefficient
  • Chemical potential
  • Compressibility (adiabatic and isothermal)
  • Expansion coefficient (isentropic and thermal)
  • Joule Thomson coefficient
  • Virial coefficients (2nd and 3rd)

For in-house correlation and software implementation LTP uses DynaSol ThermoProp (DLL and Excel Add-In). The calculation edition of this software is available for LTP service customer (in combination with EoS/measurement projects). Also NIST REFPROP compatible data files are available.