Journal ArticleDOI
A New Equation of State for Carbon Dioxide Covering the Fluid Region from the Triple‐Point Temperature to 1100 K at Pressures up to 800 MPa
Roland Span,Wolfgang Wagner +1 more
TLDR
In this article, the authors present a new equation of state in the form of a fundamental equation explicit in the Helmholtz free energy, which is able to represent even the most accurate data to within their experimental uncertainty.Abstract:
This work reviews the available data on thermodynamic properties of carbon dioxide and presents a new equation of state in the form of a fundamental equation explicit in the Helmholtz free energy. The function for the residual part of the Helmholtz free energy was fitted to selected data of the following properties: (a) thermal properties of the single‐phase region (pρT) and (b) of the liquid‐vapor saturation curve (p s, ρ′, ρ″) including the Maxwell criterion, (c) speed of soundw and (d) specific isobaric heat capacityc p of the single phase region and of the saturation curve, (e) specific isochoric heat capacityc v , (f) specific enthalpyh, (g) specific internal energyu, and (h) Joule–Thomson coefficient μ. By applying modern strategies for the optimization of the mathematical form of the equation of state and for the simultaneous nonlinear fit to the data of all these properties, the resulting formulation is able to represent even the most accurate data to within their experimental uncertainty. In the technically most important region up to pressures of 30 MPa and up to temperatures of 523 K, the estimated uncertainty of the equation ranges from ±0.03% to ±0.05% in the density, ±0.03% to ±1% in the speed of sound, and ±0.15% to ±1.5% in the isobaric heat capacity. Special interest has been focused on the description of the critical region and the extrapolation behavior of the formulation. Without a complex coupling to a scaled equation of state, the new formulation yields a reasonable description even of the caloric properties in the immediate vicinity of the critical point. At least for the basic properties such as pressure, fugacity, and enthalpy, the equation can be extrapolated up to the limits of the chemical stability of carbon dioxide. Independent equations for the vapor pressure and for the pressure on the sublimation and melting curve, for the saturated liquid and vapor densities, and for the isobaric ideal gas heat capacity are also included. Property tables calculated from the equation of state are given in the appendix.read more
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Journal ArticleDOI
Single Sheet Functionalized Graphene by Oxidation and Thermal Expansion of Graphite
Michael J. McAllister,Je-Luen Li,Douglas H. Adamson,Hannes C. Schniepp,Ahmed Abdala,Jun-Jun Liu,Margarita Herrera-Alonso,David L. Milius,Roberto Car,Robert K. Prud'homme,Ilhan A. Aksay +10 more
TL;DR: In this article, a detailed analysis of the thermal expansion mechanism of graphite oxide to produce functionalized graphene sheets is provided, where it is shown that the decomposition rate of the epoxy and hydroxyl sites exceeds the diffusion rate of evolved gases, yielding pressures that exceed the van der Waals forces holding the graphene sheets together.
Journal ArticleDOI
The IAPWS Industrial Formulation 1997 for the Thermodynamic Properties of Water and Steam
Wolfgang Wagner,J. R. Cooper,A. Dittmann,J. Kijima,Hans-Joachim Kretzschmar,A. Kruse,Radim Mareš,K. Oguchi,H. Sato,I. Stöcker,O. Šifner,Y. Takaishi,I. Tanishita,J. Trübenbach,Th. Willkommen +14 more
TL;DR: The 1967 IFC Formulation for Industrial Use (IFC-67) has been formally recognized to calculate thermodynamic properties of water and steam for any official use such as performance guarantee calculations of power cycles as mentioned in this paper.
Journal ArticleDOI
Supercritical fluid extraction and fractionation of natural matter
TL;DR: Supercritical extraction and fractionation of natural matter is one of the early and most studied applications in the field of supercritical fluids in the last 10 years, studies on the extraction of classical compounds like essential and seed oils from various sources, with or without the addition of a co-solvent have been published.
Journal ArticleDOI
Anion Effects on Gas Solubility in Ionic Liquids
TL;DR: Ionic liquids with the bis(trifluoromethylsulfonyl) imide anion had the largest affinity for CO(2), regardless of whether the cation was imidazolium, pyrrolidinium, or tetraalkylammonium.
Journal ArticleDOI
Solubilities and Thermodynamic Properties of Gases in the Ionic Liquid 1-n-Butyl-3-methylimidazolium Hexafluorophosphate
TL;DR: In this paper, the solubility of nine different gases in 1-n-butyl-3-methylimidazolium hexafluorophosphate was investigated.
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The IAPWS Formulation 1995 for the Thermodynamic Properties of Ordinary Water Substance for General and Scientific Use
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