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The second and third virial coefficients of simple fluids

“…The isotherms defined by the virial equation (1) agree adequately in the stable and weakly metastable regions at ρ/ρ c < 0.8 and T/T c < 0.9 with the results obtained by unified equations of state in [4,18]. …”

“…The experimental data on the second virial coefficient of real fluids are, as a rule, limited to the temperature range of (0.5-3.0)T c ; for the Lennard-Jones fluid, this corresponds approximately to the range of 0.7 < τ < 4.0. Therefore, for the evaluation of the general formula (18), it was used for the approximation of the second virial coefficient of the Lennard-Jones fluid in the temperature range identified above. The theoretically obtained values of the coefficients β, , and were used for correct description of low temperatures; the values of the parameters γ and n were selected such as to attain adequate agreement with the high-temperature asymptote (13).…”

“…(21) With positive and other than zero values of the parameters α, Δ′, β, γ′, n′, , and negative values of , formula (21) guarantees a physically correct behavior of the third virial coefficient in the low-and high-temperature limits. The parameters α and β are defined by the obtained temperature dependence of the second virial coefficient (18).…”

Compressed Liquid Densities of 1-Pentanol and 2-Pentanol from 313 to 363 K at Pressures to 25 MPa

“…Periods for water and nitrogen are recorded at the same conditions of the reported data. Reference densities of water and nitrogen are calculated using equations of state reported by Wagner and Pruß [29] and Span et al [30], respectively. The maximum uncertainties of the density values calculated for water and nitrogen were 0.003% [29] and 0.02% [30], respectively.…”

“…Reference densities of water and nitrogen are calculated using equations of state reported by Wagner and Pruß [29] and Span et al [30], respectively. The maximum uncertainties of the density values calculated for water and nitrogen were 0.003% [29] and 0.02% [30], respectively. The uncertainties for the measured variables were estimated to be T = (±0.03) K for temperature, P = (±0.008) MPa for pressure and ρ = (±0.20) kg·m −3 for density over the complete range of the reported data, as previously published [22,26].…”