Thermodynamic Properties of Methyl Diethanolamine

AbstractThe homogeneous density of the liquid phase is experimentally investigated for methyl diethanolamine. Data are obtained along five isotherms in a temperature range between 300 K and 360 K for pressures up to 95 MPa. Two different apparatuses are used to measure the speed of sound for the temperatures between 322 K and 450 K with a maximum pressure of 95 MPa. These measurements and literature data are used to develop a fundamental equation of state for methyl diethanolamine. The model is formulated in terms of the Helmholtz energy and allows for the calculation of all thermodynamic properties in gaseous, liquid, supercritical, and saturation states. The experimental data are represented within their uncertainties. The physical and extrapolation behavior is validated qualitatively to ensure reasonable calculations outside of the range of validity. Based on the experimental datasets, the equation of state is valid for temperatures from 250 K to 750 K and pressures up to 100 MPa.

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A Fundamental Equation of State for Chloroethene for Temperatures from the Triple Point to 430 K and Pressures to 100 MPa

International Journal of Thermophysics ◽

10.1007/s10765-021-02961-3 ◽

2022 ◽

Vol 43 (3) ◽

Author(s):

Monika Thol ◽

Florian Fenkl ◽

Eric W. Lemmon

Keyword(s):

Experimental Data ◽

Equation Of State ◽

Vinyl Chloride ◽

Triple Point ◽

Fundamental Equation ◽

Maximum Pressure ◽

Experimental Database ◽

Point Temperature ◽

Fundamental Equation Of State ◽

Triple Point Temperature

AbstractA fundamental equation of state in terms of the Helmholtz energy is presented for chloroethene (vinyl chloride). Due to its fundamental nature, it can be used to consistently calculate all thermodynamic state properties in the fluid region. Based on the underlying experimental database, it is valid from the triple-point temperature 119.31 K to 430 K with a maximum pressure of 100 MPa. In addition to the accurate reproduction of experimental data, correct extrapolation behavior during the development of the equation was attained. This enables the equation to be applied in modern mixture frameworks.

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Speed-of-Sound Measurements and a Fundamental Equation of State for Propylene Glycol

Journal of Physical and Chemical Reference Data ◽

10.1063/5.0050021 ◽

2021 ◽

Vol 50 (2) ◽

pp. 023105

Author(s):

Tim Eisenbach ◽

Christian Scholz ◽

Roland Span ◽

Diego Cristancho ◽

Eric W. Lemmon ◽

...

Keyword(s):

Equation Of State ◽

Propylene Glycol ◽

Speed Of Sound ◽

Fundamental Equation ◽

Fundamental Equation Of State

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Speeds of Sound in n-Hexane and n-Heptane at Temperatures from (233.33 to 353.21) K and Pressures up to 20 MPa

International Journal of Thermophysics ◽

10.1007/s10765-020-02778-6 ◽

2020 ◽

Vol 42 (2) ◽

Author(s):

Christian W. Scholz ◽

Markus Richter

Keyword(s):

Experimental Data ◽

Speed Of Sound ◽

Sound Speed ◽

Path Length ◽

Equations Of State ◽

Fundamental Equation ◽

Pulse Timing ◽

Combined Uncertainty ◽

Fundamental Equation Of State ◽

Pulse Echo

AbstractThe speed of sound in high-purity n-hexane and n-heptane was experimentally studied utilizing the double-path length pulse-echo technique. Measurements with each alkane were carried out at temperatures from (233 to 353) K with pressures up to 20 MPa. Considering the uncertainty contributions from temperature, pressure, path-length calibration, pulse timing and sample purity, the relative expanded combined uncertainty (k = 2) in the speed of sound in n-hexane ranges from (0.012 to 0.042) % over the investigated ranges of pressure and temperature; for n-heptane, the uncertainty varies from (0.014 to 0.018) %. The sound speed data measured in n-hexane were among the data used for the development of a new fundamental equation of state, which is, however, not described in this work. The experimental data of n-heptane can be considered appropriate for modeling purposes and validation of existing equations of state.

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