Determining Optimal EOS
for an Application

Department Publications


Technical Publications

Contact Information

Brandon L. Ridens
Research Engineer
Pipeline Simulation
(210) 522-3459

Most engineering analysis tools use physical properties of gas and liquid mixtures from embedded equations of state (EOS). EOS models implement mixing laws using data from pure components to calculate mixture properties. This can result in significant deviations from actual measured properties, particularly for points near the phase envelope or critical regions as well as non-binary mixtures containing heavier hydrocarbons, CO2, sour or corrosive components, and "wet gas" combinations. Errors in properties such as density, speed of sound, or specific heat will affect the accuracy of meter measurements, performance calculations (enthalpy and entropy), and pulsation analyses (amplitudes and frequencies). SwRI has performed extensive mixture property testing with a wide range of components over extensive pressure and temperature ranges to build a database for this analysis.

To help reduce the error in analysis tools and metering, SwRI will determine:

  • The most accurate EOS for your application
  • Expected margins of error
Large range of water thermophysical property predictions when using various EOS

Large range of water thermophysical property predictions when using various EOS

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Southwest Research Institute® (SwRI®), headquartered in San Antonio, Texas, is a multidisciplinary, independent, nonprofit, applied engineering and physical sciences research and development organization with 10 technical divisions.