Speeds of Sound in n-Pentane at Temperatures from 233.50 to 473.15 K at Pressures up to 390 MPa

Abstract

We report speeds of sound in n-pentane measured using two similar apparatuses, located at Ruhr University Bochum (RUB) and Imperial College London (ICL), covering different ranges of temperature and pressure. At RUB, measurements were conducted at temperatures from (233.50 to 353.20) K with pressures up to 20 MPa, while temperatures from (263.15 to 473.15) K with pressures up to 390 MPa were covered at ICL. Accounting for the uncertainties in temperature, pressure, path-length calibration, and pulse timing, the relative expanded combined uncertainty (k = 2) in the speed of sound varied from 0.015% to 0.18% over the whole region investigated.Nevertheless, small differences averaging at 0.13% are found between the two data sets in the region of overlap. The experimental data reported in this work have been partly used in the development of a new fundamental equation of state for n-pentane.

Speeds of Sound in Methanol at Temperatures from 233.33 to 353.21 K at Pressures up to 20 MPa

“…The experimental procedure applied to conduct the speed of sound measurements in the scope of this work was adapted from previous works [59,60]. The stainless steel bottle containing the sample of methanol was attached to the evacuated speed of sound apparatus and carefully heated.…”

“…Speed of sound measurements in methanol were conducted employing the doublepath length pulse-echo technique with an apparatus according to the design of Meier and Kabelac [58]. The experimental set-up has been used for speed of sound measurements of several liquids in our previous works [59][60][61][62]; thus, it is only explained in brief at this point. A detailed description with illustrations of the measuring cell and a schematic drawing of the entire measuring system can be taken from the work of Gedanitz et al [63].…”

“…2are determined from calibration measurements with high-purity water. Here, the calibration remains the same as presented in our previous work [60], where measurements at T = 274. 15 [67] with the experimental speeds of sound being reported within the uncertainty of the equation of state of 0.005%.…”

“…In order to avoid contact with the humidity of ambient air, the methanol sample was transferred to a stainless steel bottle within the dry inert argon atmosphere of a glove box that was manufactured in-house. Prior to use, the sample was degassed by repeated freeze-pump-thaw cycles, as described in our previous works [59][60][61][62].…”

“…The combined expanded uncertainty in speed of sound was estimated according to our previous studies [59,60], where the approach is explained in detail, by developing the following term with consideration of Eqs. (1) and (2):…”