Automated High-Temperature PVT Apparatus With Data for Propane

Area of Science:

• Thermodynamics and Physical Chemistry
• Materials Science and Engineering
• Chemical Engineering

Background:

• Accurate pressure-volume-temperature (PVT) and compressibility data are essential for characterizing supercritical fluids.
• Existing experimental methods may have limitations in temperature, pressure range, or accuracy for supercritical fluid studies.
• Understanding supercritical fluid behavior is critical for applications in chemical processing, energy, and materials science.

Purpose of the Study:

• To describe a novel apparatus for comprehensive PVT and compressibility measurements on supercritical fluids.
• To achieve high-accuracy density determination across a wide range of temperatures (near room temperature to 600 °C) and pressures (to 35 MPa).
• To validate the apparatus performance using a known substance, propane.

Main Methods:

• Employs two complementary experimental techniques: Burnett expansions and isochoric measurements.
• Burnett expansions generate compressibility factor and density data along supercritical isotherms.
• Isochoric measurements extend the temperature range, with densities determined via intersection with Burnett isotherms or gravimetrically.
• Computerized control and data logging facilitate automated, long-duration experiments.

Main Results:

• The apparatus successfully measured PVT and compressibility data for supercritical fluids within the specified temperature and pressure ranges.
• Density data obtained for propane up to 325 °C showed excellent agreement with existing literature values.
• Estimated accuracy of the density data is ±0.1 percent.

Conclusions:

• The developed apparatus is a reliable and accurate tool for supercritical fluid property measurements.
• The combined use of Burnett expansions and isochoric measurements allows for broad state surface coverage.
• The system's automation enables routine, unattended operation for extended experimental periods.