“… 11 Binodal curves of confined and bulk n C 5 , i C 5 , and neo C 5 . The circles and diamonds are for confined C 5 in a (30, 30) SWNT and a nanoslit from gauge-cell MC, the squares are for bulk C 5 from GEMC, and the dashed curves are for bulk C 5 from experiments. − …”
Capillary phase transitions of linear (from C(1) to C(12)) and branched (C(5) isomers) alkanes in single-walled carbon nanotubes have been investigated using the gauge-cell Monte Carlo simulation. The isotherm at a supercritical temperature increases monotonically with chemical potential and coincides with that from the traditional grand canonical Monte Carlo simulation, whereas the isotherm at a subcritical temperature exhibits a sigmoid van der Waals loop including stable, metastable, and unstable regions. Along this loop, the coexisting phases are determined using an Maxwell equal-area construction. A generic confinement effect is found that reduces the saturation chemical potential, lowers the critical temperature, increases the critical density, and shrinks the phase envelope. The effect is greater in a smaller diameter nanotube and is greater in a nanotube than in a nanoslit.
“… 11 Binodal curves of confined and bulk n C 5 , i C 5 , and neo C 5 . The circles and diamonds are for confined C 5 in a (30, 30) SWNT and a nanoslit from gauge-cell MC, the squares are for bulk C 5 from GEMC, and the dashed curves are for bulk C 5 from experiments. − …”
Capillary phase transitions of linear (from C(1) to C(12)) and branched (C(5) isomers) alkanes in single-walled carbon nanotubes have been investigated using the gauge-cell Monte Carlo simulation. The isotherm at a supercritical temperature increases monotonically with chemical potential and coincides with that from the traditional grand canonical Monte Carlo simulation, whereas the isotherm at a subcritical temperature exhibits a sigmoid van der Waals loop including stable, metastable, and unstable regions. Along this loop, the coexisting phases are determined using an Maxwell equal-area construction. A generic confinement effect is found that reduces the saturation chemical potential, lowers the critical temperature, increases the critical density, and shrinks the phase envelope. The effect is greater in a smaller diameter nanotube and is greater in a nanotube than in a nanoslit.
“…Its constants (11) are Tc = 516.74 K, Pc = 32.304 atm, pc = 0.542 g/cm3, mol wt = 186.057 zc = 0.2612, BGl Equations 91 and 92 give the range of translation from 0.0445 to 0.0565, and 0.056 will be chosen to give a better fit near twice the critical density. If n is taken as 1.3 in TRn, dPR/dTR = 7.9 for the critical isometric at TR = 1.25, and this compares favorably with The last example is normal pentane, whose constants (7) are Tc = 469.65, Pc = 33.25 atm, Vc = 304 cm3/g-mol, zc = 0.2623, the NBT = 309.19 K, BG = -0.352, and mol wt = 72.151. PR and 1/TR at the boiling point give = 7.35 from the generalized vapor-pressure diagram.…”
Section: The Best Two-term Cubic Equation Of Statementioning
confidence: 97%
“…VIII. A form which is not in the literature but has interesting properties is obtained from eq 7 It is useful to put these into dimensionless forms with PCVC/RTC = Zc, so that eq 22…”
Section: P=mentioning
confidence: 99%
“…Equations 91 and 92 give tPc/RTc ranging from 0.045 to 0.057, and 0.057 will be selected to favor the highest densities. If n is taken as 1 in TRn, dPR/dTR for the critical isometric at TR = 1.25 is 7.35, which is equal to M. Thus, an excellent equation for rc-C5H12 is Now a recent publication (7) has reviewed the PVT data on n-C5H12 and given a table of compressibility factors for a temperature of 470 K which is almost the critical temperature. Thus, a check was made to determine how well eq 103 would predict.…”
Section: The Best Two-term Cubic Equation Of Statementioning
An analysis is made of volume-cubic equations of state, starting with the most general generating equation from which all specific forms can easily be derived. One equation is shown to be both the simplest and the best in performance. A new quantity, the z-chart sum, is presented, which is a useful way to compare all equations of state, whether cubic or otherwise, while at the same time permitting excellent predictions of the second virial coefficient at the critical temperature from the critical compressibility factor. Extensive comparisons of reliable experimental PVT data with a number of equations of state are given for a wide range of substances from nonpolar to polar, and these demonstrate the superiority of the simplest two-term cubic equation.
“…Thus, eq 10a is expected to describe accurately the volumetric properties of both liquid and vapor phases independently of the number of segments in the molecule. 2 Vapor pressures and molar volumes of light n -alkanes: open circles, experimental data for C 1 −C 4 , C 5 , C 7 ; solid lines, results from eq 10a; dotted lines, data from PR-EOS. 3 The 2nd and the 3rd virial coefficients of n -pentane: solid circles, literature data for the 2nd virial coefficient; open circles, literature data for the 3rd virial coefficient; solid lines, results from eq 10a; dotted lines, results from PR-EOS.…”
This work proposes a new equation of state (EOS) based on molecular theory for the prediction of thermodynamic properties of real fluids. The new EOS uses a novel repulsive term, which gives the correct hard sphere close packed limit and yields accurate values for hard sphere and hard chain virial coefficients. The pressure obtained from this repulsive term is corrected by a combination of van der Waals and Dieterici potentials. No empirical temperature functionality of the parameters has been introduced at this stage. The novel EOS predicts the experimental volumetric data of different compounds and their mixtures better than the successful EOS of Peng and Robinson. The prediction of vapor pressures is only slightly less accurate than the results obtained with the Peng-Robinson equation that is designed for these purposes. The theoretically based parameters of the new EOS make its predictions more reliable than those obtained from purely empirical forms.
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