Triple Point Research Articles

SIM.T-K9.3: Standard platinum resistance thermometer ITS-90 realizations from the Hg triple point to the Zn freezing point

Main textThis report shows the results of a bilateral comparison of temperature standards between Instituto Nacional de Metrologia, Qualidade e Tecnologia (Inmetro, Brazil), and Trinidad and Tobago Bureau of Standards (TTBS, Trinidad and Tobago), carried out between January and July of 2020. The measurands of this comparison were the W(t90) ratios of two Standard Platinum Resistance Thermometers (SPRTs), used as transfer standards, measured at the zinc freezing point (Zn FP, 419.527 °C), tin freezing point (Sn FP, 231.928 °C), gallium melting point (Ga MP, 29.7646 °C), triple point of water (TPW, 0.01 °C) and mercury triple point (Hg TP, -38.8344 °C).To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCT, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Collision enhancement in shocks and its implication on gas-phase detonations: A molecular dynamics and gas-kinetic theory study

Conventional assumption in gas-phase detonations, where shock compression is decoupled from chemical kinetics, predicates on the shock and triple point structures being treated as perfect discontinuities. However, the shock is a region of high translational nonequilibrium three to five mean free paths in thickness. In this study, we use molecular dynamics simulations to probe Ar and N2 shocks focusing on the collision statistics in the shock front. Translationally superheated molecules were identified, as suggested by Zeldovich (Dokl. Akad. Nauk 248 (1979) 349–351), which raise the collision temperature and potentially enhance chemical reaction rates within and ahead of the shock front. We evaluated this reaction rate enhancement effect on stoichiometric H2/O2 ZND detonation and found the effect to be negligible. The triple point region is observed to have a similar distribution of translationally superheated molecules. The temperature in the triple point region in Ar is substantially higher than that in N2; the difference could impact detonation and deflagration-to-detonation characteristics due to diluent differences.

Bubble flow analysis using multi-phase field method

In simulations of gas-liquid two-phase flows using conventional interface capture methods, we observed that when bubbles come close to each other, they tend to merge numerically, despite experimental evidence indicating that they would repel each other. Given the significant impact of sequential numerical coalescence on flow patterns, it is necessary to regulate the merging behavior of close bubbles. To address this issue, we introduced the Multi-Phase Field (MPF) method, which mitigates bubble coalescence by applying an independent fluid fraction function to each bubble. In this study, we employed the MPF based on the N-phase model [7] to minimize numerical errors associated with surface interactions at triple junction points. Additionally, we implemented the Ordered Active Parameter Tracking (OAPT) method [9] to efficiently store several hundreds of fluid fraction functions. To validate the MPF method, we conducted analysis of turbulent bubbly pipe flows and compared the results against experimental data from Colin et al [12]. The validation results showed reasonable agreements with respect to the bubble distribution and the flow velocity profiles.

Kaş Bay: Evidence of a 20 km-diameter complex impact structure on the Turkey-Greece frontier

Extensive field work, mineralogical and petrographic investigations show strong evidence for a complex, hypervelocity impact structure protruding into the Mediterranean Sea at the Turkey-Greece border. The Kaş Bay structure with a diameter of around 20 km, is structurally altered, since it coincides with the triple point of the Anatolian, Aegean, and African plates. The target rocks, entirely comprising sedimentary carbonate, show evidence of shock metamorphism, along with a wealth of significant finds and numerous indications of a clear and strong impact overprint. A Pleistocene age is inferred from related stratigraphical evidence.

Скоростные напоры и их соотношения за стационарными маховскими конфигурациями ударных волн, распространяющихся в потоке газа

We analyzed the parameters of gas streams, which form after the triple shock configurations occurring in Mach reflection with normal Mach shock (so called stationary Mach configuration). We suppose that this stationary Mach configuration moves in a counter flow with arbitrary velocity (and corresponding Mach number). Analyzing relations of the dynamic pressures across the contact discontinuity, which emanates from the triple point of the Mach reflection, we have shown that the streams after the triple shock configuration differs much in their translational action on surrounding objects.

Supplementary comparison on a platinum resistance thermometer calibration from -70 °C to 250 °C

Main textThis supplementary comparison was about the calibration of platinum resistance thermometers in the range of -70 °C to 250 °C. Four laboratories participated in the comparison: Emirates Metrology Institute (EMI) from United Arab Emirates, SASO-NMCC from Saudi Arabia, QGOSM from Qatar and Tubitak UME from Türkiye. These Institutes are full or associated (Tubitak UME) members of the GULFMET Regional Metrology Organization.The pilot institute was Emirates Metrology Institute, who also provided the two transfer platinum resistance thermometers and monitor their stability during the comparison.The measurements of the comparison were performed between April 2019 and February 2021 and the circulation of the instruments was without problems, except for a delay of four months between the laboratories QGOSM and EMI due to the Coronavirus pandemic.The weighted mean of the measurements from all laboratories was used to produce the W ratios and R 0.01 reference values of the thermometers and no laboratory was excluded from this weighted mean. Note that this comparison is an RMO supplementary comparison, so the weighted mean values generated are used only as a baseline for reporting the results, and they have no particular meaning of reference values in the sense of the key comparisons.The results show a satisfactory agreement between the participating laboratories (|En| <1), except for two set-points: -35 °C and 100 °C, for one of the two transfer thermometers, for one of the laboratories. Combined expanded uncertainties for R 0.01 were equivalent to about 0.004 °C for the laboratories using water triple point cells as a reference, and 0.010 °C for QGOSM laboratory using ice point as reference. For the other measurement points, R values, were having equivalent combined expanded uncertainties ranging from 0.0060 °C to 0.010 °C for UME, 0.008 °C to 0.016 °C for EMI, 0.012 °C to 0.024 °C for SASO-NMCC and 0.014 °C to 0.054 °C for QGOSM. The mentioned uncertainties refer to the most stable of the transfer thermometers used in the comparison.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCT, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Research on the effect of microelement salt with fertilizer

The visual-polythermal method was used to study the solubility of components in the ZnSO4 – (NH4)2SO4 – H2O system over the temperature interval of -22.0°С to +36.1°С. Solubility and characteristics of the constituents of the system at different temperatures and concentrations were studied to show the physicochemical interactions between zinc sulfate and ammonium sulfate. The phase description delineates the areas of ice crystallization, (NH4)2SO4, ZnSO4ꞏ(NH4)2SO4ꞏ6H2O, and ZnSO4. A solubility diagram was drawn and a new compound, ZnSO4ꞏ(NH4)2SO4ꞏ6H2O, was isolated. The system ZnSO4 – (NH4)2SO4 – H2O was investigated using thirteen inner sections. At the double and triple points of the system, the equipoise composition of solutions and crystallization temperatures were clarified. The analysis was carried out using contemporary physicochemical analysis methods to confirm the identity of the obtained compound. Analytical data on physicochemical changes, thermal stability and chemical decomposition of the ZnSO4ꞏ(NH4)2SO4ꞏ6H2O sample with temperature change were presented. All the diffractographic changes in the X-ray pattern of a new compound, in particular, the set of distances between the planes, the activation of their reflection angles, and the diffraction lines confirm the individuality of the new compound.

Surface phase diagrams from nested sampling.

Studies in atomic-scale modeling of surface phase equilibria often focus on temperatures near zero Kelvin due to the challenges in calculating the free energy of surfaces at finite temperatures. The Bayesian-inference-based nested sampling (NS) algorithm allows for modeling phase equilibria at arbitrary temperatures by directly and efficiently calculating the partition function, whose relationship with free energy is well known. This work extends NS to calculate adsorbate phase diagrams, incorporating all relevant configurational contributions to the free energy. We apply NS to the adsorption of Lennard-Jones (LJ) gas particles on low-index and vicinal LJ solid surfaces and construct the canonical partition function from these recorded energies to calculate ensemble averages of thermodynamic properties, such as the constant-volume heat capacity and order parameters that characterize the structure of adsorbate phases. Key results include determining the nature of phase transitions of adsorbed LJ particles on flat and stepped LJ surfaces, which typically feature an enthalpy-driven condensation at higher temperatures and an entropy-driven reordering process at lower temperatures, and the effect of surface geometry on the presence of triple points in the phase diagrams. Overall, we demonstrate the ability and potential of NS for surface modeling.

EURAMET.T-K9 regional key comparison ITS-90 SPRT calibration from the Ar TP to the Zn FP

Main textThis is a report to the Technical Committee for Thermometry of EURAMET (EURAMET TC-T) on the regional key comparison EURAMET.T-K9 of SPRT calibration on the International Temperature Scale of 1990 (ITS-90), from 83.8058 K (the Ar triple point) to 692.677 K (the Zn fixed point). The transfer standards used are long-stem SPRTs.EURAMET.T-K9 is an RMO key comparison linked to the CIPM key comparison CCT-K9. The comparison is organized in five separate collapsed Stars, each one having a CCT-K9 participant as pilot, which provides the link to the KCRV of CCT-K9. Four to five participating laboratories are involved in each Star. The pilots of the five Stars are LNE-Cnam, PTB, INRiM, VSL, NPL. LNE-Cnam is also the coordinator of the comparison, in charge of the collection of the measurement reports from all participants and the preparation of the final report.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCT, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Experimental study of breakup and atomization characteristics of liquid carbon dioxide jet under high-pressure environment

Considering the working conditions of a Mg/CO2 rocket engine for Mars exploration, an experimental investigation was carried out to study the breakup and atomization properties of a liquid CO2 jet in a high-pressure environment. It is shown that the pressure ratio has a significant effect on the location and process of jet evaporation, resulting in significant difference in jet morphology and breakup characteristic. Two dividing points were identified, one near the CO2 triple point and the other near the saturation point. As the pressure ratio increases, the thermodynamic driving force for jet breakup weakens, leading to larger droplet sizes. The breakup length of the free round jet and Sauter mean diameter are functions of the Weber number and Jacob number, which are influenced by vapor content, injection velocity, and gas-liquid density ratio, in the mass flowrate range of 5.9–9.1 g/(mm2·s). A thermodynamic mechanism dominates when the ambient pressure in the atomize room is low enough, resulting in an unimodal distribution of droplet sizes. When the ambient pressure is in the range of 1–2.5 MPa, both thermodynamic and mechanical breakup mechanisms are active, resulting in a bimodal distribution of droplet sizes.

A parameter-free staggered-grid Lagrangian scheme for two-dimensional compressible flow problems

The present study aims to develop a parameter-free staggered-grid Lagrangian scheme that avoids the empirical parameters needed for artificial viscosity and anti-hourglass force. The artificial viscosity is equal to the pressure jump, which is constructed by the relationship between pressure and velocity. The anti-hourglass force is established using pressure compensation, which is the difference in pressure between sub-cells belonging to the same primary cell. The scheme maintains the conservation of total mass, momentum, and energy. Numerical experiments show that the scheme is highly robust for extreme flow problems with different fine meshes such as Sedov, Noh, Saltzmann triple point and Rayleigh–Taylor instability. The robust parameter-free scheme is well suited for multi-physics problems and engineering applications.

Intrinsic AC Dielectric Breakdown Strength of Polyimide Films at the Extreme: New Breakthrough Insights on Thickness Dependence

AbstractTo date, the AC dielectric breakdown strength of polyimide (PI) films, as for most polymers, is understood to follow a thickness dependency with a measured power law exponent, n ≈ 0.5. However, this work experimentally demonstrates that the AC dielectric strength of PI films is quasi‐thickness independent. Evidence is presented showing that the thickness dependency described in the literature can be explained by an extrinsic failure mode, driven by partial discharges occurring at the dielectric‐oil‐electrode triple point. Triple points can be avoided by electrode encapsulation, which subsequently recovers a purely intrinsic failure mode for PI films over a large thickness range. Consequently, the AC dielectric strength of thick PI films is intrinsic and quasi‐thickness independent, at least for film thickness up to 60 µm. For the first time, a “theoretical” AC breakdown field for PI films is reported as ≈520 Vrms µm−1. Finally, the highest experimental breakdown field values are obtained here with 505 Vrms µm−1 and 705 Vµm−1 under AC and DC fields, respectively.

The Nanoscale Wetting Parameter and Its Role in Interfacial Phenomena: Phase Transitions in Nanopores.

Through analysis of the statistical mechanical equations for a thin adsorbed film (gas, liquid, or solid) on a solid substrate or confined within a pore, it is possible to express the equilibrium thermodynamic properties of the film as a function of just two dimensionless parameters: a nanoscale wetting parameter, αw, and pore width, H*. The wetting parameter, αw, is defined in terms of molecular parameters for the adsorbed film and substrate and so is applicable at the nanoscale and for films of any phase. The main assumptions in the treatment are that (a) the substrate structure is not significantly affected by the adsorbed layer and (b) the diameter of the adsorbate molecules is not very small compared to the spacing of atoms in the solid substrate. We show that different surface geometries of the substrate (e.g., slit, cylindrical, and spherical pores) and various models of wall heterogeneity can be accounted for through a well-defined correction to the wetting parameter; no new dimensionless variables are introduced. Experimental measurements are reported for contact angles for various liquids on several planar substrates and are shown to be closely correlated with the nanoscale wetting parameter. We apply this approach to phase separation in nanopores of various geometries. Molecular simulation results for the phase diagram in confinement, obtained by the flat histogram Monte Carlo method, are reported and are shown to be closely similar to experimental results for capillary condensation, melting, and the triple point. The value of the wetting parameter, αw, is shown to determine the qualitative behavior (e.g., increase vs decrease in the melting temperature, capillary condensation vs evaporation), whereas the pore width determines the magnitude of the confinement effect. The triple point temperature and pressure for the confined phase are always lower than those for the bulk phase for all cases studied.

Thermal faceting on the ductility-dip cracking fracture surfaces of nickel-based alloys – Occurrence, characterization, and implications for the cracking mechanism

Ductility-dip cracking (DDC) fracture surfaces containing thermal faceting (TF) are documented in this study. Research began with the discovery of TF on the DDC fracture surface in the weld metal of high-chromium nickel (Ni)-based filler metal 52M, a valuable alloy to the nuclear industry. Fracture surfaces were generated using strain-to-fracture (STF) and simulated strain ratcheting (SSR) testing on a Gleeble® thermomechanical simulator. Initial fractography performed by scanning electron microscopy (SEM) revealed faceting with preferred grain orientations and faceting interacting with void nucleation near grain boundary (GB) triple points. Internal voids were exposed via metallography, where TF was also observed on the free surface. A thin orientation- and site-specific foil was extracted from the faceted fracture surface using focused ion beam (FIB) nanofabrication. Subsequent scanning transmission electron microscopy (STEM) characterization down to atomic-resolution revealed the facets have perfect crystallographic orientations parallel to close-packed directions. Sharp edges and transitions between individual facets on the scale of individual atomic columns and atomic planes were observed. An analysis of the deformation microstructure and the chemical composition underneath the faceted surface showed a low dislocation density and no evidence of localized segregation or diffusion, respectively. These findings have led to the development of a hypothesis related to the interdependence of TF and DDC and support initial claims regarding TF formation in DDC voids at elevated temperatures.

Synergistic boost of catalytic activity in ZrTe topological catalyst via multiple topologically-electronic states

Topological materials feature highly-active topological surface states and high carrier mobility, making them promising catalysts. While ongoing research centers on topological catalysis, most topological semimetal catalysts tend to showcase either a singular topological electronic state or a lone highly catalytic surface, imposing limitations on overall efficiency. Our study highlights ZrTe as a standout catalyst for hydrogen evolution, boasting multiple topological states that excel across various surfaces. ZrTe exhibits a Weyl nodal ring and a triple degenerate nodal point near the Fermi energy, resulting in topological surface states on multiple surfaces. Notably, the (010) and (001) surfaces exhibit remarkable catalytic performance, with Gibbs free energy (ΔGH*) values surpassing that of the Pt metal. Our work establishes a robust and unequivocal link between catalysis and topological properties on the catalytic surfaces, revealing a linear correlation between ΔGH* and topological surface state density. ZrTe emerges as an exceptional topological catalyst, with both of its topological states significantly contributing to the catalytic performance on distinct surfaces. This pioneering discovery offers a valuable platform for advancing catalyst research in the concept of topological catalysts.

SPATIAL AND STRUCTURAL COMPLEXITY OF CEREBRAL HEMISPHERES IN MALE AND FEMALE BRAIN: FRACTAL AND QUANTITATIVE ANALYSES OF MRI BRAIN SCANS

Objectives: The aim of the present study was to compare the features of the structural complexity of the cerebral hemispheres in men and women using fractal analysis of outlined and skeletonized images, as well as quantitative analysis of digital skeletons of the cerebral hemispheres. Material and Methods: Magnetic resonance imaging brain scans of 100 individuals aged 18-86 years (44 males and 56 females) were investigated. Five tomographic sections of each brain were selected for morphometric study (4 coronal and 1 axial sections). The sections were preprocessed, and outlined and skeletonized images were obtained. Fractal analysis was conducted using the two-dimensional box counting method, and fractal dimensions of outlined and skeletonized images were determined. Additionally, quantitative analysis of skeletonized images was performed, determining the following parameters: branches, junctions, end-point voxels, junction voxels, slab voxels, triple points, quadruple points, average branch length, and maximum branch length. Results: We observed that both variants of fractal dimension in males and females did not show significant differences, although most quantitative parameters in males were larger than those in females. Conclusions: The spatial and structural complexity of the cerebral hemispheres, as characterized by fractal dimensions, is almost indistinguishable between males and females. However, in some individual tomographic sections, the male brain may exhibit a slightly higher number of end-point voxels, corresponding to the gyri of the cerebral hemispheres. The obtained data can be used in clinical practice for diagnostic purposes (e.g., for detecting malformations) and for theoretical studies in neuroanatomy.

Structure and Dynamic Inhomogeneity of Liquids on the Liquid–Gas Coexistence Curve Near the Triple Point

Structure and Dynamic Inhomogeneity of Liquids on the Liquid–Gas Coexistence Curve Near the Triple Point

Modelling of Carbon Dioxide Venting in Carbon Capture and Storage Studies: Design and Safety Implications

The reduction of the impact of carbon dioxide on the environment is a key driver of the energy transition, which will progressively reduce the use of fossil fuels and will promote the development of viable technologies. This process will be based on renewable energy sources to reduce, to any possible extent, the production and the release of carbon dioxide into the atmosphere. CCS (Carbon Capture and Storage) projects are more and more an ineludible stage of this process. In the last decade, a significant segment of chemical engineering research has been devoted to the management of carbon dioxide release scenarios, which can result both from an accidental loss of containment or from an emergency venting of carbon dioxide streams. This gas is asphyxiating and toxic, depending on concentration levels. Consequently, acquiring familiarity with its dispersion modelling is a key task for process and process safety engineers. On the other hand, carbon dioxide presents a very peculiar behaviour, as it is a dense gas and, below the triple point, its release can produce solid formation. The article presents a relatively simple multi-stage validated model, covering the release scenario from the source, as a heavy gas, up to the neutral Gaussian dispersion, considering also the very low temperatures possibly resulting from the JT (Joule Thomson) effect. Two case studies, carried out through the Megaris Platform, illustrate the application of the methodology. It can be useful in the design phase and in the QRA studies, to properly size and locate the venting stack and to minimize any health upsets for the operators

Effects of activation energy on irregular detonation structures in supersonic flow

In this work, high-precision numerical simulations of detonations in supersonic hydrogen–oxygen premixed gases with different activation energies are carried out. The open-source program Adaptive Mesh Refinement in Object-Oriented C++ is adopted, and the monotone upstream–centered scheme for conservation laws total variation diminishing numerical scheme is utilized to solve the Euler equations coupled with a one-step, two-component reaction model. The wave structure characteristics of the irregular cellular detonation process are obtained, and its initiation and propagation characteristics under different activation energies are analyzed in depth. The results show that, unlike a regular detonation wave structure, the Mach stem of an irregular detonation wave is prone to bifurcation in a supersonic mixture with high activation energy. In addition to the incident shock wave and the Mach stem structure, a hybrid shock wave structure also appears between the two due to the random generation of weak triple points. Moreover, the leading shock wave intensity of the irregular detonation weakens, resulting in the generation of many unburned jets whose sizes and shapes depend on the triple point type. Although the oscillation amplitude of the irregular detonation is large and its regularity is weak, the detonation wave can achieve approximate dynamic stability in the channel.

Experimental investigation of a triple point in a dusty plasma

In this work, we present the first experimental observation of a triple point in a strongly coupled complex plasma medium. Initially, a 2D crystalline structure of the dust component consisting of monodisperse micrometer-sized particles is created. The evolution of this monolayer as a function of the discharge voltage is then investigated and, in the course of this evolution, the co-existence of three distinct phases of the system consisting of a liquid region and two crystalline regions with square and hexagonal lattice configurations is observed. Two different transition sequences are identified in the system, depending on the initial dust density of the monolayer. The particles in the fluid region have high kinetic energy. Before the emergence of a triple state, it is found that the particles in the different lattice geometries show different in-plane or out-of-plane oscillations. It is conjectured that a complex or mixed instability that originates in the system in a localized manner gives rise to the formation of the triple point in our experiments.