Densities and dielectric constants for some LPG components and mixtures at cryogenic and standard temperatures
✍ Scribed by C.C. Luo; R.C. Miller
- Publisher
- Elsevier Science
- Year
- 1981
- Tongue
- English
- Weight
- 796 KB
- Volume
- 21
- Category
- Article
- ISSN
- 0011-2275
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✦ Synopsis
Measured dielectric constants and molar densities are reported for a number of liquefied petroleum gas (LPG) components and mixtures at cryogenic temperatures (220-250 K) and at standard temperature (15.6°C). A tabulation of consistent component properties is presented. Volume changes on mixing are found to be less than about O. 1% of the mixture molar volumes for all systems studied at cryogenic conditions (c., 228 K). Somewhat larger contractions on mixing were observed for some propane-rich binary mixtures at 288.71 K (60°F). Results for all mixtures studied confirmed that a mole-fraction average of component Clausius-Mossott/ function values can be used as an accurate estimate of the mixture CM value. Molar densities calculated under this rule agree with measured values within 0.2%.
Densities and dielectric constants for some LPG components and mixtures at cryogenic and standard temperatures C.C. Luo and R.C. Miller
This work continues that reported in Reference 1, to provide density and dielectric-constant data for systems of interest relative to liquefied petroleum gas (LPG). This material is predominately propane with lesser amounts of other lowmolecular-weight saturated hydrocarbons (C2 through Cs). LPG from refinery sources may contain small amounts of unsaturated species of similar molecular weight. LPG is handled at elevated pressure with ambient temperatures or as a cryogenic fluid at low pressure. Methanol is used as a lubricant in certain cryogenic pumps and may become a trace LPG component through packing leakage.
Accurate densities are needed in custody transfer operations for light petroleum liquids. It may be possible to use dielectric-constant measurements as substitutes for direct density measurements in custody transfer and other fluid handling and storage operations. Molar density (p) and dielectric constant (e) are related through the Clausius-Mossotti function (CM):
In the previous work a , densities and dielectric constants were determined for LPG components and propane-rich binary liquid mixtures with up to 10 mole % ethylene, ethane, propylene, propane, normal butane, and isobutane. Temperatures were near 228.4 K, with pressures held just above the bubble points. The measured mixture densities were used to calculate molar volumes and volume changes on mixing (excess volumes). Excess volumes were found to be less than 0.1% of the mixture molar volumes for propane + propylene, isobutane, or normal butane. For the mixtures with ethane or ethylene, excess volumes were negative (contraction on mixing) and were as large as 0.3% of the mixture volumes.
It was demonstrated that component Clausius-Mossotti function values can be combined by a mole-fraction