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Li X, Jin Y. Thermodynamic crossovers in supercritical fluids. Proc Natl Acad Sci U S A 2024; 121:e2400313121. [PMID: 38652745 PMCID: PMC11067041 DOI: 10.1073/pnas.2400313121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2024] [Accepted: 03/26/2024] [Indexed: 04/25/2024] Open
Abstract
Can liquid-like and gas-like states be distinguished beyond the critical point, where the liquid-gas phase transition no longer exists and conventionally only a single supercritical fluid phase is defined? Recent experiments and simulations report strong evidence of dynamical crossovers above the critical temperature and pressure. Despite using different criteria, many existing theoretical explanations consider a single crossover line separating liquid-like and gas-like states in the supercritical fluid phase. We argue that such a single-line scenario is inconsistent with the supercritical behavior of the Ising model, which has two crossover lines due to its symmetry, violating the universality principle of critical phenomena. To reconcile the inconsistency, we define two thermodynamic crossover lines in supercritical fluids as boundaries of liquid-like, indistinguishable, and gas-like states. Near the critical point, the two crossover lines follow critical scalings with exponents of the Ising universality class, supported by calculations of theoretical models and analyses of experimental data from the standard database. The upper line agrees with crossovers independently estimated from the inelastic X-ray scattering data of supercritical argon, and from the small-angle neutron scattering data of supercritical carbon dioxide. The lower line is verified by the equation of states for the compressibility factor. This work provides a fundamental framework for understanding supercritical physics in general phase transitions.
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Affiliation(s)
- Xinyang Li
- Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing100049, China
| | - Yuliang Jin
- Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing100049, China
- Center for Theoretical Interdisciplinary Sciences, Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou, Zhejiang325001, China
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2
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Bugeat B, Boldini PC, Hasan AM, Pecnik R. Instability in strongly stratified plane Couette flow, with application to supercritical fluids. JOURNAL OF FLUID MECHANICS 2024; 984:jfm.2024.193. [PMID: 38584669 PMCID: PMC7615809 DOI: 10.1017/jfm.2024.193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
This paper addresses the stability of plane Couette flow in the presence of strong density and viscosity stratifications. It demonstrates the existence of a generalised inflection point that satisfies the generalised Fjørtoft's criterion of instability when a minimum of kinematic viscosity is present in the base flow. The characteristic scales associated with this minimum are identified as the primary controlling parameters of the associated instability, regardless of the type of stratification. To support this finding, analytical stability models are derived in the long wave approximation using piecewise linear base flows. Numerical stability calculations are carried out to validate these models and to provide further information on the production of disturbance vorticity. All instabilities are interpreted as arising from the interaction between two vorticity waves. Depending on the type of stratification, these two waves are produced by different physical mechanisms. When both strong density and viscosity stratifications are present, we show that they result from the concurrent action of shear and inertial baroclinic effects. The stability models developed for simple fluid models ultimately shed light on a recently observed unstable mode in supercritical fluids (Ren et al., J. Fluid Mech., vol. 871, 2019, pp. 831-864), providing a quantitative prediction of the stability diagram and identifying the dominant mechanisms at play. Furthermore, our study suggests that the minimum of kinematic viscosity reached at the Widom line in these fluids is the leading cause of their instability. The existence of similar instabilities in different fluids and flows (e.g., miscible fluids) is finally discussed.
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Affiliation(s)
- B. Bugeat
- Process and Energy Department, Delft University of Technology, Leeghwaterstraat 39, 2628 CB Delft, The Netherlands
| | - P. C. Boldini
- Process and Energy Department, Delft University of Technology, Leeghwaterstraat 39, 2628 CB Delft, The Netherlands
| | - A. M. Hasan
- Process and Energy Department, Delft University of Technology, Leeghwaterstraat 39, 2628 CB Delft, The Netherlands
| | - R. Pecnik
- Process and Energy Department, Delft University of Technology, Leeghwaterstraat 39, 2628 CB Delft, The Netherlands
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3
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Simeski F, Ihme M. Supercritical fluids behave as complex networks. Nat Commun 2023; 14:1996. [PMID: 37032390 PMCID: PMC10083177 DOI: 10.1038/s41467-023-37645-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Accepted: 03/22/2023] [Indexed: 04/11/2023] Open
Abstract
Supercritical fluids play a key role in environmental, geological, and celestial processes, and are of great importance to many scientific and engineering applications. They exhibit strong variations in thermodynamic response functions, which has been hypothesized to stem from the microstructural behavior. However, a direct connection between thermodynamic conditions and the microstructural behavior, as described by molecular clusters, remains an outstanding issue. By utilizing a first-principles-based criterion and self-similarity analysis, we identify energetically localized molecular clusters whose size distribution and connectivity exhibit self-similarity in the extended supercritical phase space. We show that the structural response of these clusters follows a complex network behavior whose dynamics arises from the energetics of isotropic molecular interactions. Furthermore, we demonstrate that a hidden variable network model can accurately describe the structural and dynamical response of supercritical fluids. These results highlight the need for constitutive models and provide a basis to relate the fluid microstructure to thermodynamic response functions.
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Affiliation(s)
- Filip Simeski
- Department of Mechanical Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Matthias Ihme
- Department of Mechanical Engineering, Stanford University, Stanford, CA, 94305, USA.
- Department of Photon Science, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA.
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Liu (刘洪勤) H. From the vapour–liquid coexistence region to the supercritical fluid: the van der Waals fluid. Mol Phys 2022. [DOI: 10.1080/00268976.2022.2155260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Hongqin Liu (刘洪勤)
- Integrated High Performance Computing Branch, Shared Services Canada, Montreal, Canada
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Lundin AA, Chaikina YA, Shushin AI, Umanskii SY. On the Capabilities of Optical Diagnostics Methods to Monitor the State of Supercritical Fluids near the Widom Line. RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY B 2022. [DOI: 10.1134/s1990793122080115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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6
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Liu H. The mean-field dividing interface is united with the Widom line. Chem Phys Lett 2022. [DOI: 10.1016/j.cplett.2022.139982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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7
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Vestrick S, Fischer C, Khoukaz A. Crossing the Widom line: Cluster formation as sensitive probe of supercritical fluids. J Supercrit Fluids 2022. [DOI: 10.1016/j.supflu.2022.105686] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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8
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Widom line of supercritical CO2 calculated by equations of state and molecular dynamics simulation. J CO2 UTIL 2022. [DOI: 10.1016/j.jcou.2022.102075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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9
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widom and extrema lines as CRITERIA for OPTIMIZING operating conditions IN supercritical processes. J Supercrit Fluids 2022. [DOI: 10.1016/j.supflu.2022.105587] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Zanetti-Polzi L, Daidone I, Amadei A. A general statistical mechanical model for fluid system thermodynamics: Application to sub- and super-critical water. J Chem Phys 2022; 156:044506. [DOI: 10.1063/5.0079206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Laura Zanetti-Polzi
- Center S3, CNR-Institute of Nanoscience, Via Campi 213/A, 41125 Modena, Italy
| | - Isabella Daidone
- Department of Physical and Chemical Sciences, University of L’Aquila, via Vetoio (Coppito 1), 67010 L’Aquila, Italy
| | - Andrea Amadei
- Department of Chemical and Technological Sciences, University of Rome “Tor Vergata”, Via della Ricerca Scientifica, I-00185 Rome, Italy
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11
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The hybrid ergodic lattice gas model for critical fluids and the molecular nature of the critical point. J Supercrit Fluids 2021. [DOI: 10.1016/j.supflu.2021.105505] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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12
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Quasi-equilibrium phase coexistence in single component supercritical fluids. Nat Commun 2021; 12:4630. [PMID: 34330902 PMCID: PMC8324840 DOI: 10.1038/s41467-021-24895-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2020] [Accepted: 07/05/2021] [Indexed: 11/24/2022] Open
Abstract
In their supercritical state simple fluids are generally thought to assume a homogeneous phase throughout all combinations of pressures and temperatures, although various response functions or transport properties may exhibit anomalous behavior, characterizing a state point as either more gas-like or liquid-like, respectively. While a large body of results has been compiled in the last two decades regarding the details of the supercritical phase in thermodynamic equilibrium, far less studies have been dedicated to out-of-equilibrium situations that nevertheless occur along with the handling of substances such as carbon dioxide or Argon. Here we consider successive compression-expansion cycles of equal amounts of Argon injected into a high-pressure chamber, traversing the critical pressure at two times the critical temperature. Due to expansion cooling, the fluid temporarily becomes sub-critical, and light scattering experiments show the formation of sub-micron-sized droplets and nanometer-scale clusters, both of which are distinct from spontaneous density fluctuations of the supercritical background and persist for a surprisingly long time. A kinetic rate model of the exchange of liquid droplets with the smaller clusters can explain this behavior. Our results indicate non-equilibrium aspects of supercritical fluids that may prove important for their processing in industrial applications. In their supercritical state simple fluids are generally thought to assume a homogeneous phase throughout. Lee et al. find that liquid droplets temporarily formed in a supercritical background after sub-critical injection can survive for a surprisingly long time.
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Maxim F, Karalis K, Boillat P, Banuti DT, Marquez Damian JI, Niceno B, Ludwig C. Thermodynamics and Dynamics of Supercritical Water Pseudo-Boiling. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2021; 8:2002312. [PMID: 33552857 PMCID: PMC7856905 DOI: 10.1002/advs.202002312] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 10/12/2020] [Indexed: 06/12/2023]
Abstract
Supercritical fluid pseudo-boiling (PB), recently brought to the attention of the scientific community, is the phenomenon occurring when fluid changes its structure from liquid-like (LL) to gas-like (GL) states across the Widom line. This work provides the first quantitative analysis on the thermodynamics and the dynamics of water's PB, since the understanding of this phase transition is mandatory for the successful implementation of technologies using supercritical water (scH2O) for environmental, energy, and nanomaterial applications. The study combines computational techniques with in situ neutron imaging measurements. The results demonstrate that, during isobaric heating close to the critical point, while water density drops by a factor of three in the PB transitional region, the system needs >16 times less energy to increase its temperature by 1 K than to change its structure from LL to GL phase. Above the PB-Widom line, the structure of LL water consists mainly of tetramers and trimers, while below the line mostly dimers and monomers form in the GL phase. At atomic level, the PB dynamics are similar to those of the subcritical water vaporization. This fundamental knowledge has great impact on water science, as it helps to establish the structure-properties relationship of scH2O.
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Affiliation(s)
- Florentina Maxim
- Laboratory for Chemical Thermodynamics“Ilie Murgulescu” Institute of Physical ChemistrySplaiul Independentei 202Bucharest060021Romania
- Laboratory for Bioenergy and Catalysis (LBK)ENE DivisionPaul Scherrer InstituteVilligen PSI5232Switzerland
| | | | - Pierre Boillat
- Electrochemistry Laboratory (LEC)ENE DivisionPaul Scherrer InstituteVilligen PSI5232Switzerland
- Laboratory for Neutron Scattering and Imaging (LNS)NUM DivisionPaul Scherrer InstituteVilligen PSI5232Switzerland
| | - Daniel T. Banuti
- Department of Mechanical EngineeringThe University of New MexicoMSC01 1150AlbuquerqueNM87131USA
| | | | - Bojan Niceno
- Laboratory for Scientific Computing and Modelling (LSM)NES DivisionPaul Scherrer InstituteVilligen PSI5232Switzerland
- Eidgenössische Technische Hochschule Zürich (ETHZ)MAVT‐LKEZurich8092Switzerland
| | - Christian Ludwig
- Laboratory for Bioenergy and Catalysis (LBK)ENE DivisionPaul Scherrer InstituteVilligen PSI5232Switzerland
- École Polytechnique Fédérale de Lausanne (EPFL)ENAC IIE GR‐LUDLausanne1015Switzerland
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Abdulagatov IM, Skripov PV. Thermodynamic and Transport Properties of Supercritical Fluids: Review of Thermodynamic Properties (Part 1). RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY B 2021. [DOI: 10.1134/s1990793120070192] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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15
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16
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Banuti D, Raju M, Ihme M. Between supercritical liquids and gases – Reconciling dynamic and thermodynamic state transitions. J Supercrit Fluids 2020. [DOI: 10.1016/j.supflu.2020.104895] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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17
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Ha MY, Yoon TJ, Tlusty T, Jho Y, Lee WB. Universality, Scaling, and Collapse in Supercritical Fluids. J Phys Chem Lett 2020; 11:451-455. [PMID: 31878784 DOI: 10.1021/acs.jpclett.9b03360] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Supercritical fluid (SCF) is known to exhibit salient dynamic and thermodynamic crossovers and an inhomogeneous molecular distribution. However, the question as to what basic physics underlies these microscopic and macroscopic anomalies remains open. Here, using an order parameter extracted by machine learning, the fraction of gas-like (or liquid-like) molecules, we find simplicity and universality in SCF: First, all isotherms of a given fluid collapse onto a single master curve described by a scaling relation. The observed power law holds from the high-temperature and -pressure regime down to the critical point where it diverges. Second, phase diagrams of different compounds collapse onto their master curves by the same scaling exponent, thereby demonstrating a putative law of corresponding supercritical states in simple fluids. The reported results support a model of the SCF as a mixture of two interchangeable microstates, whose spatiotemporal dynamics gives rise to unique macroscopic properties.
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Affiliation(s)
- Min Young Ha
- School of Chemical and Biological Engineering, Institute of Chemical Processes , Seoul National University , Seoul 08826 , Republic of Korea
| | - Tae Jun Yoon
- School of Chemical and Biological Engineering, Institute of Chemical Processes , Seoul National University , Seoul 08826 , Republic of Korea
| | - Tsvi Tlusty
- Center for Soft and Living Matter , Institute for Basic Science (IBS) , Ulsan 44919 , Republic of Korea
- Department of Physics , Ulsan National Institute of Science and Technology (UNIST) , Ulsan 44919 , Republic of Korea
| | - YongSeok Jho
- Department of Physics and Research Institute of Natural Science , Gyeongsang National University , Jinju 52828 , Republic of Korea
| | - Won Bo Lee
- School of Chemical and Biological Engineering, Institute of Chemical Processes , Seoul National University , Seoul 08826 , Republic of Korea
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18
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Ghosh K, Krishnamurthy CV. Frenkel line crossover of confined supercritical fluids. Sci Rep 2019; 9:14872. [PMID: 31619694 PMCID: PMC6795815 DOI: 10.1038/s41598-019-49574-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Accepted: 08/28/2019] [Indexed: 11/09/2022] Open
Abstract
We investigate the temperature evolution of dynamics and structure of partially confined Lennard Jones (LJ) fluids in supercritical phase along an isobaric line in the P-T phase diagram using molecular dynamics simulations. We compare the Frenkel line (FL) crossover features of partially confined LJ fluids to that of the bulk LJ fluids in supercritical phase. Five different spacings have been chosen in this study and the FL crossover characteristics have been monitored for each of these spacings for temperatures ranging from 240 K to 1500 K keeping the pressure fixed at 5000 bar. We characterize the FL crossover using density of states (DoS) function and find that partially confined supercritical fluids (SCF) exhibit a progressive shift of FL crossover point to higher temperatures for smaller spacings. While the DoS perpendicular to the walls shows persistent oscillatory modes, the parallel component exhibits a smooth crossover from an oscillatory to non-oscillatory characteristics representative of FL crossover. We find that the vanishing of peaks in DoS parallel to the walls indicates that the SCF no longer supports shear mode excitations and could serve as an identifier of the FL crossover for confined systems just as is done for the bulk. Layer heights of density profiles, self-diffusivity and the peak heights of radial distribution function parallel to the walls also feature the FL crossover consistent with the DoS criteria. Surprisingly, self-diffusivity undergoes an Arrhenius to super-Arrhenius crossover at low temperatures for smaller spacings as a result of enhanced structural order evidenced via pair-excess entropy. This feature, typical of glass-forming liquids and binary supercooled liquids, is found to develop from the glass-like characteristic slowdown and strong caging in confined supercritical fluid, evidenced via mean squared displacement and velocity autocorrelation function respectively, over intermediate timescales.
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Affiliation(s)
- Kanka Ghosh
- Department of Physics, Indian Institute of Technology Madras, Chennai, 600036, India.
| | - C V Krishnamurthy
- Department of Physics, Indian Institute of Technology Madras, Chennai, 600036, India
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19
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Visualization of supercritical water pseudo-boiling at Widom line crossover. Nat Commun 2019; 10:4114. [PMID: 31530816 PMCID: PMC6748934 DOI: 10.1038/s41467-019-12117-5] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Accepted: 08/21/2019] [Indexed: 11/19/2022] Open
Abstract
Supercritical water is a green solvent used in many technological applications including materials synthesis, nuclear engineering, bioenergy, or waste treatment and it occurs in nature. Despite its relevance in natural systems and technical applications, the supercritical state of water is still not well understood. Recent theories predict that liquid-like (LL) and gas-like (GL) supercritical water are metastable phases, and that the so-called Widom line zone is marking the crossover between LL and GL behavior of water. With neutron imaging techniques, we succeed to monitor density fluctuations of supercritical water while the system evolves rapidly from LL to GL as the Widom line is crossed during isobaric heating. Our observations show that the Widom line of water can be identified experimentally and they are in agreement with the current theory of supercritical fluid pseudo-boiling. This fundamental understanding allows optimizing and developing new technologies using supercritical water as a solvent. Supercritical water exists in gas- and liquid-like forms, but these have not been distinguished yet at the macroscale. Here the authors investigate supercritical water interacting with microporous carbon by neutron imaging, and observe the coexistence of gas- and liquid-like states upon crossing the Widom line.
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Yoon TJ, Ha MY, Lee WB, Lee YW. A corresponding-state framework for the structural transition of supercritical fluids across the Widom delta. J Chem Phys 2019; 150:154503. [DOI: 10.1063/1.5086467] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Tae Jun Yoon
- School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University, Seoul 08826, South Korea
| | - Min Young Ha
- School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University, Seoul 08826, South Korea
| | - Won Bo Lee
- School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University, Seoul 08826, South Korea
| | - Youn-Woo Lee
- School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University, Seoul 08826, South Korea
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21
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Takemoto A, Kinugawa K. Quantumness and state boundaries hidden in supercritical helium-4: A path integral centroid molecular dynamics study. J Chem Phys 2018; 149:204504. [DOI: 10.1063/1.5053988] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Ayumi Takemoto
- Division of Chemistry, Graduate School of Humanities and Sciences, Nara Women’s University, Nara 630-8506, Japan
| | - Kenichi Kinugawa
- Division of Chemistry, Graduate School of Humanities and Sciences, Nara Women’s University, Nara 630-8506, Japan
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22
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Bakai O, Bratchenko M, Dyuldya S. Three-state mesoscopic model of a heterophase fluid in application to the gas-liquid and dielectric-semiconductor-metal transformations in expanded mercury. J Mol Liq 2018. [DOI: 10.1016/j.molliq.2018.03.068] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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23
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Yoon TJ, Lee YW. Current theoretical opinions and perspectives on the fundamental description of supercritical fluids. J Supercrit Fluids 2018. [DOI: 10.1016/j.supflu.2017.11.022] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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24
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Hobold GM, da Silva AK. Dimensionless, fluid-independent equations for heat and momentum transfer in supercritical fluids. J Supercrit Fluids 2018. [DOI: 10.1016/j.supflu.2017.09.016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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25
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Ghosh K, Krishnamurthy CV. Structural behavior of supercritical fluids under confinement. Phys Rev E 2018; 97:012131. [PMID: 29448330 DOI: 10.1103/physreve.97.012131] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Indexed: 11/07/2022]
Abstract
The existence of the Frenkel line in the supercritical regime of a Lennard-Jones (LJ) fluid shown through molecular dynamics (MD) simulations initially and later corroborated by experiments on argon opens up possibilities of understanding the structure and dynamics of supercritical fluids in general and of the Frenkel line in particular. The location of the Frenkel line, which demarcates two distinct physical states, liquidlike and gaslike within the supercritical regime, has been established through MD simulations of the velocity autocorrelation (VACF) and radial distribution function (RDF). We, in this article, explore the changes in the structural features of supercritical LJ fluid under partial confinement using atomistic walls. The study is carried out across the Frenkel line through a series of MD simulations considering a set of thermodynamics states in the supercritical regime (P=5000 bar, 240K≤T≤1500K) of argon well above the critical point. Confinement is partial, with atomistic walls located normal to z and extending to "infinity" along the x and y directions. In the "liquidlike" regime of the supercritical phase, particles are found to be distributed in distinct layers along the z axis with layer spacing less than one atomic diameter and the lateral RDF showing amorphous-like structure for specific spacings (packing frustration) and non-amorphous-like structure for other spacings. Increasing the rigidity of the atomistic walls is found to lead to stronger layering and increased structural order. For confinement with reflective walls, layers are found to form with one atomic diameter spacing and the lateral RDF showing close-packed structure for the smaller confinements. Translational order parameter and excess entropy assessment confirms the ordering taking place for atomistic wall and reflective wall confinements. In the "gaslike" regime of the supercritical phase, particle distribution along the spacing and the lateral RDF exhibit features not significantly different from that due to normal gas regime. The heterogeneity across the Frenkel line, found to be present both in bulk and confined systems, might cause the breakdown of the universal scaling between structure and dynamics of fluids necessitating the determination of a unique relationship between them.
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Affiliation(s)
- Kanka Ghosh
- Department of Physics, Indian Institute of Technology Madras, Chennai 600036, India
| | - C V Krishnamurthy
- Department of Physics, Indian Institute of Technology Madras, Chennai 600036, India
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26
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Sharma D, Erriguible A, Amiroudine S. Cooling beyond the boundary value in supercritical fluids under vibration. Phys Rev E 2018; 96:063102. [PMID: 29347440 DOI: 10.1103/physreve.96.063102] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Indexed: 11/07/2022]
Abstract
Supercritical fluids when subjected to simultaneous quench and vibration have been known to cause various intriguing flow phenomena and instabilities depending on the relative direction of temperature gradient and vibration. Here we describe a surprising and interesting phenomenon wherein temperature in the fluid falls below the imposed boundary value when the walls are quenched and the direction of vibration is normal to the temperature gradient. We define these regions in the fluid as sink zones, because they act like sink for heat within the fluid domain. The formation of these zones is first explained using a one-dimensional (1D) analysis with acceleration in constant direction. Subsequently, the effect of various boundary conditions and the relative direction of the temperature gradient to acceleration are analyzed, highlighting the necessary conditions for the formation of sink zones. It is found that the effect of high compressibility and the action of self-weight (due to high acceleration) causes the temperature to change in the bulk besides the usual action of piston effect. This subsequently affects the overall temperature profile thereby leading to the formation of sink zones. Though the examined 1D cases differ from the current two-dimensional (2D) cases, owing to the direction of acceleration being normal as compared to parallel in case of former, the explanations pertaining to 1D cases are judiciously utilized to elucidate the formation of sink zones in 2D supercritical fluids subjected to thermal quench and vibrational acceleration. The appearance of sink zones is found to be dependent on several factors such as proximity to the critical point and acceleration. A surface three-dimensional plot illustrating the effect of these parameters on onset time of sink zones is presented to further substantiate these arguments.
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Affiliation(s)
- D Sharma
- Université Bordeaux, I2M, UMR CNRS 5295, 16 Av. Pey-Berland, 33607 Pessac, France
| | - A Erriguible
- Bordeaux INP, I2M, UMR CNRS 5295, 16 Av. Pey-Berland, 33607 Pessac, France
| | - S Amiroudine
- Université Bordeaux, I2M, UMR CNRS 5295, 16 Av. Pey-Berland, 33607 Pessac, France
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Bryk T, Gorelli FA, Mryglod I, Ruocco G, Santoro M, Scopigno T. Behavior of Supercritical Fluids across the "Frenkel Line". J Phys Chem Lett 2017; 8:4995-5001. [PMID: 28945381 DOI: 10.1021/acs.jpclett.7b02176] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The "Frenkel line" (FL), the thermodynamic locus where the time for a particle to move by its size equals the shortest transverse oscillation period, has been proposed as a boundary between recently discovered liquid-like and gas-like regions in supercritical fluids. We report a simulation study of isothermal supercritical neon in a range of densities intersecting the FL. Specifically, structural properties and single-particle and collective dynamics are scrutinized to unveil the onset of any anomalous behavior at the FL. We find that (i) the pair distribution function smoothly evolves across the FL displaying medium-range order, (ii) low-frequency transverse excitations are observed below the "Frenkel frequency", and (iii) the high-frequency shear modulus does not vanish even for low-density fluids, indicating that positive sound dispersion characterizing the liquid-like region of the supercritical state is unrelated to transverse dynamics. These facts critically undermine the definition of the FL and its significance for any relevant partition of the supercritical phase.
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Affiliation(s)
- T Bryk
- Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine , 1 Svientsitskii Street, UA-79011 Lviv, Ukraine
- Institute of Applied Mathematics and Fundamental Sciences, Lviv Polytechnic National University , UA-79013 Lviv, Ukraine
| | - F A Gorelli
- Istituto Nazionale di Ottica INO-CNR , I-50019 Sesto Fiorentino, Italy
- European Laboratory for Non Linear Spectroscopy, LENS , I-50019 Sesto Fiorentino, Italy
| | - I Mryglod
- Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine , 1 Svientsitskii Street, UA-79011 Lviv, Ukraine
| | - G Ruocco
- Dipartimento di Fisica, Universita di Roma La Sapienza , I-00185 Roma, Italy
- Center for Life Nano Science @Sapienza, Istituto Italiano di Tecnologia , 295 Viale Regina Elena, I-00161 Roma, Italy
| | - M Santoro
- Istituto Nazionale di Ottica INO-CNR , I-50019 Sesto Fiorentino, Italy
- European Laboratory for Non Linear Spectroscopy, LENS , I-50019 Sesto Fiorentino, Italy
| | - T Scopigno
- Dipartimento di Fisica, Universita di Roma La Sapienza , I-00185 Roma, Italy
- Center for Life Nano Science @Sapienza, Istituto Italiano di Tecnologia , 295 Viale Regina Elena, I-00161 Roma, Italy
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