DePriester Chart for Hydrocarbons

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This Demonstration applies a DePriester chart, a set of nomograms to find the vapor-liquid equilibrium ratio (the gas phase mole fraction divided by the liquid phase mole fraction, known as the -value) for a series of hydrocarbons. Select one of three hydrocarbons: methane, propane or -decane. Use sliders to change the pressure and temperature; a green line connects these two points. The green circle indicates where to read the -value on the chart, which is also displayed above the chart. The -values for other hydrocarbons can also be read from the chart.

Contributed by: Majed N. Aldossary (October 2016)
Additional contributions by: Rachael L. Baumann and John L. Falconer
(University of Colorado Boulder, Department of Chemical and Biological Engineering)
Open content licensed under CC BY-NC-SA



Here is an example of how to use a DePriester chart for propane at 70 psia and 20 °F:

1. Use the sliders to set the pressure and temperature.

2. The green line connects these two points.

3. The -value is where the green line intersects the curve for propane ().


[1] J. M. Smith, H. C. Van Ness and M. M. Abbott, Introduction to Chemical Engineering Thermodynamics, 7th ed., Boston: McGraw-Hill, 2005.

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