The pressure-enthalpy driven molecular dynamics technique, developed in a companion paper
1, is used to compute various thermodynamic properties for the Lennard–Jones (LJ) fluid. These properties ...include the vapor–liquid coexistence curve, the critical point, the Joule–Thomson coefficient and inversion curve, and a complete vapor-compression refrigeration (VCR) cycle. The technique provides a simple and effective means of utilizing molecular dynamics to sample different thermodynamic state points. Results are as accurate as those obtained using Monte Carlo (MC) methods.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The complete Joule–Thomson (JT) inversion curve for carbon dioxide is calculated using molecular simulations. A two center Lennard–Jones model with an embedded point quadrupole is used to model the ...fluid–fluid interactions. The simulation results agree quantitatively with all available experimental data. Comparison with commonly used equations of state provides only a modest agreement, with the highest discrepancies being observed at the high temperature branch of the inversion curve.
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IJS, IMTLJ, KILJ, KISLJ, NUK, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
In this paper the Joule–Thomson (JT) inversion curve has been used to test the predictive capabilities of some recent cubic equations of state. The three and two parameter cubic equations of state ...included modified Patel–Teja (MPT), modified Peng–Robinson (MPR) by Melhem–Saini–Goodwin, Iwai–Margerum–Lu (IML), modified Redlich–Kwong (MRK) by Souahi–Sator–Albane–Kies–Chitoure and the four parameter Trebble–Bishnoi (TB) equation of state were chosen for our study. All of the equations studied here except MRK have been given good prediction of the low-temperature branch of the JT inversion curve. In the high-temperature region and the peak of the curves depend on components the MPR, MPT and TB equations provided relatively fair agreement with experimental data and Gunn, Chueh and Prausnitz (GCP) correlated inversion curve. We considered the effect of the constants in
α function of the MPT equation of state, in its ability of the prediction of the JT inversion curve. The consequence of volumetric parameter on the high pressure and relatively high temperature region has been shown. Isenthalp calculation has also been included.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
By using the pressure and entropy of a system obtained from the grand potential of ideal quantum gases confined in a long tube with a fixed transverse cross section of area and the fundamental ...relations of thermodynamics, expression for the heat capacity at given longitudinal pressure and area of cross section is derived, from which the linear expansion coefficient and the Joule-Thomson coefficient (JTC) of the system are obtained. Moreover, the effects of the finite size on the heat capacity, expansion coefficient and JTC of the system are discussed in detail. It is significant to find that the absolute values of the JTCs of confined ideal quantum gases increase with the decrease of the systemic size and temperature.
In recent years, China has explored and exploited several high-pressure deep gas fields. Normally, high-pressure gas wells are gathered and processed through multichoke manifolds on well sites, ...creating hazards such as high wellhead flowing pressure (Pt) and high risk for on-site operation personnel. Moreover, downhole chokes have been used in place of surface chokes. In doing this, the Joule–Thomson (JT) effect is geothermally regulated, alleviating the formation of hydrates in surface facilities. However, its applicability to high-pressure gas wells is less explored. In an effort to guide its use, the objective of this study is to set selection criteria in terms of the allowable wellhead Pt and gas flow rate. First, isenthalpic lines are separately estimated for dry gas and high liquid hydrocarbon (LHC) content gas condensate at various inlet temperatures with the use of commercial software. Next, by analysis of the resulting isenthalpic curves, several results are obtained on the JT inversion curves and throttling process through a choke. Third, building on these insights, a method for projecting the maximum Pt is presented, leading to a value of 52.5 MPa. Finally, multiparameter models are separately run for two deep gas wells (8100 m and 5000 m), reinforcing the result of the pressure upper limit while maintaining a maximum daily gas production of 14 E4 m
3
. Both upper limits with a maximum Pt of 52.5 MPa and daily gas production of 14 E4 m
3
are corroborated with field data records. These findings are vital to the selection of a viable high-pressure gas well for applying the downhole throttling technique.
The Joule-Thomson effect reflects the interaction among constituent particles of macroscopic system. For classical ideal gas, the corresponding .Joule-Thomson coefficient is vanishing while it is ...non-zero for ideal quantum gas due to the quantum degeneracy. In recent years, much attention is paid to the unitary Fermi gas with infinite two-body scattering length. According to universal analysis, the thermodynamical law of unitary Fermi gas is similar to that of non-interacting ideal gas, which can be explored by the virial theorem P = 2E/3V. Based on previous works, we further study the unitary Fermi gas properties. The effective chemical potential is introduced to characterize the nonlinear levels crossing effects in a strongly interacting medium. The changing behavior of the rescaled Joule-Thomson coefficient according to temperature manifests a quite different behavior from that for ideal Fermi gas.
We present simulation results for the volume expansivity, isothermal compressibility, isobaric heat capacity, Joule-Thomson coefficient and speed of sound for carbon dioxide (CO 2 ) in the ...supercritical region, using the fluctuation method based on Monte Carlo simulations in the isothermal-isobaric ensemble. We model CO 2 as a quadrupolar two-center Lennard-Jones fluid with potential parameters reported in the literature, derived from vapor-liquid equilibria (VLE) of CO 2 . We compare simulation results with an equation of state (EOS) for the two-center Lennard-Jones plus point quadrupole (2CLJQ) fluid and with a multiparametric EOS adjusted to represent CO 2 experimental data. It is concluded that the VLE-based parameters used to model CO 2 as a quadrupolar two-center Lennard-Jones fluid (both simulations and EOS) can be used with confidence for the prediction of thermodynamic properties, including those of industrial interest such as the speed of sound or Joule-Thomson coefficient, for CO 2 in the supercritical region, except in the extended critical region.
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BFBNIB, GIS, IJS, KISLJ, NUK, PNG, UL, UM, UPUK
Five equations of state, modified Peng-Robinson by Danesh et al. (MPR1), modified SRK equation of state by Mathias and Copeman (MSRK), Vdw11, Harmens-Knapp (HK) and modified Peng-Robinson equation of ...state by Ruzy (MPR2) were compared in predicting of the inversion curve of some fluids. This enable us to judge the accuracy of the results obtained from different equations of state. MSRK and HK equations of state give good prediction of the low-temperatures branch of the inversion curve and are closely matched with the experimental inversion curve. As a corollary to the present study, we have perceived that the agreement of the MPR2 and Vdw11 equations of state with the inversion curve are inadequate. We also calculated maximum inversion temperature and maximum inversion pressure for every component used in this work.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
We have solved numerically the nonlinear partial differential equation that links speed of sound and compression factor subjected to boundary conditions in the gaseous phase. This method has as ...similar accuracy as other numerical method based on an initial-values numerical integration in the low-density regime, but for higher densities, this new approach is more accurate and less sensitive to errors in both boundary conditions and speed-of-sound. The method was tested by comparing our numerical calculations against a reference equation of state in the fluid region of densities up to the critical density and temperatures between slightly above the critical temperature and four times the critical temperature. We also analysed and estimated uncertainties of derived thermodynamic properties from this method. Finally, the method was applied to argon and ethane experimental data.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
