High-temperature Liquid Research Articles

Diagram of constituent crystalline phases in a Nd–Fe–B–Cu sintered magnet by in-situ high-temperature synchrotron X-ray diffraction and its thermodynamic interpretation

A crystalline phase diagram of a Nd–Fe–B–Cu sintered magnet up to 1100 °C was determined through in-situ synchrotron X-ray diffraction using a new sample mounting method that prevents high-temperature contact reactions between the sample and the quartz capillary tube container. Using this newly developed method, we successfully observed almost identical phase diagrams during heating and cooling, indicating thermodynamic equilibrium. In addition, we obtained changes in the constituent phase fraction after quenching. Temperature-reversible changes in the dhcp-Nd fraction were observed from 475 °C to 650 °C, corresponding to a eutectic reaction in the Nd–Cu phase. The fcc-NdOx fraction decreased with the increase in the Nd2O3 fraction above 1000 °C, which behavior was attributed to a phase change from fcc-NdOx to high-temperature liquid and hcp-Nd2O3 phases. The measurements verify the thermodynamic database recently constructed for CALPHAD calculations of the Nd–Fe–B–Cu–O system by assuming the local thermodynamic equilibrium of the Nd oxides within the microstructure of the magnet.

Measurement of molten salt spectral radiation characteristics at high temperature using transmittance device without optical window

As a key heat storage medium, the spectral radiation and thermal characteristics of molten salts are crucial. Considering the effect of measurement accuracy by multiple reflections and refractions between samples and the optical window in the traditional measurement, and the corrosion of the sample to the materials of optical windows, a new method and device for measuring radiation properties of high-temperature liquid based on the transmission method and double thickness method is proposed in this study. This device removes windows, keeps high-temperature membrane then allows light source transmits directly to obtain the transmittance and optical constants. In present work, Solar Salt and Hetic were heated up to 673 K and the spectral radiation was measured by this new device, the refractive index n of Hitec in 500–1050 nm wavelength is about 1.42 and the absorption index κ is 2 × 10−7–5 × 10−7, For Solar salt, the n in measurement band is around 1.45, and the κ is 1.5 × 10−7–3 × 10−7.

Influence of alkaline species on the high temperature lubrication of molten carbonate

Ionic liquid with the melting points lower than 100 °C is a promising lubricant used ranging from automotive industry to aerospace application, to reduce the friction consumed energy loss and wear caused failure. This work investigated the high temperature lubrication effect of three different molten alkaline carbonate (high-temperature ionic liquid). The results suggest that the lubrication properties of the alkaline carbonate is alkaline species dependent, the carbonate of potassium shows a better lubrication than sodium and lithium carbonate from 730 to 825 °C. At 920 °C, the alkaline carbonate decomposes and reacts with iron oxide to form an alkali ferrite, the tribo-layer of the reactant shows promising anti-wear, and the Li2Fe3O4 has a better lubricity than NaFeO2 and KFeO2. This study reports the concept of high-temperature ionic liquid lubricant, particularly on the roles of alkaline species. The high-temperature ionic liquid lubricant concept can potentially open up a new direction for the design and application of novel high temperature lubricants.

Multiple-gas cooling method for constant-pressure heat capacity measurement of liquid metals using aerodynamic levitator.

Until now, heat capacity measurements performed with levitation techniques have required accurate knowledge of the sample's emissivity beforehand. For a sample levitated using an aerodynamic levitator, it experiences both radiative and forced convective heat loss. The sample's emissivity only allows for the calculation of the radiative heat loss term, and a model has yet to be developed to accurately describe the total combined heat loss for aerodynamic levitation (ADL). In this study, we will introduce a novel multiple-gas cooling method for heat capacity measurement for ADL where two types of inert levitation gases (Ar and Kr) with different thermal conductivities were used to generate two cooling curves for the same sample. For samples being cooled at different cooling rates, the total heat loss is the same. The radiative heat loss was expressed using Stefan-Boltzmann's law, and the convective heat loss using Ranz-Marshall's equation. The two independent parameters (i.e., emissivity and heat capacity) of one given sample could then be solved using the two independent cooling curves. The heat capacities of gold, copper, nickel, iron, and palladium around the melting pointwere measured using this method. The multiple-gas cooling method for heat capacity measurement introduced in this study is the first heat capacity measurement method available for ADL and can be performed for materials with unknown emissivity. This newly developed method is important for the study of the thermophysical properties of high-temperature liquids, especially molten oxides with low electrical conductivity.

Storing Energy from External Power Supplies Using Phase Change Materials and Various Pipe Configurations

Phase change materials are commonly used for energy storage. Heat transfer enhancement and heat storage are the two main goals in this paper. A cylindrical pipe covered with phase change material is investigated numerically. Ideally, a high temperature liquid flows through the pipe, resulting in heat transferred to the phase change material. To enhance the heat transfer, various configurations involving the addition of a twisted tape inside of the pipe and the use of helical shape pipes were investigated. A straight pipe with no twisted tape insert was also analyzed and used as a benchmark case. All the configurations had constant properties such as material selection, overall size, pipe diameter and inlet Reynold’s number, so the performance could be compared under similar conditions. All initial configurations were simulated and the heat transfer rate, Nusselt number, friction factor and performance evaluation criterion (PEC) of the designs were determined. It was found that the heat transfer rate and Nusselt number of all the various designs yielded higher results than the reference straight pipe configuration. Additionally, due to the added complexity in the flow caused by the insert, the friction factor of all the configurations was also higher. The helical pipe configuration was the only configuration that had a PEC higher than that of the reference straight pipe. This is because the negative impacts caused by the friction factor outweighed the gains in Nusselt number for the twisted tape designs. It was also hypothesized that lowering the inner diameter of the helical pipe would increase the PEC. Further simulations with modified inner diameters were done to test the hypothesis. The simulations confirmed the hypothesis, as the pipes with inner diameters 0.75 and 0.5 cm led to a 50% and 150% increase in the PEC respectively, when compared to an inner diameter of 1 cm. It was also determined that smaller inner diameters led to lower outlet temperatures meaning a higher percentage of the thermal energy from the fluid was transferred to the phase change material.

Thermodynamic and Structural Properties of CuCrO2 and CuCr2O4: Experimental Investigation and Phase Equilibria Modeling of the Cu–Cr–O System

This work considers the equilibria between the stable phases of the Cr–Cu–O ternary chemical system at atmospheric pressure and in a large temperature range that includes the high-temperature liquid phase. Based on a thorough evaluation of literature data, we performed complementary experimental investigations of solid-phase properties (especially the mixed oxides) by implementation of spark plasma sintering and microanalysis, high-temperature X-ray diffraction combined with Rietveld analysis, differential thermal analysis, and thermogravimetry. We show that neither the spinel CuCr2O4 nor the delafossite CuCrO2 phases exhibit significant cationic nonstoichiometry. We provide an assessment of the thermodynamic functions of the spinel up to 1200 K, taking into account the α/β phase transition. We propose, for the first time, a consistent thermodynamic description of the Cr–Cu–O system based on the Calphad method, allowing the computation of reactions and phase equilibria, including the high-temperature liquid phase described by the modified quasichemical model.

Extra-thermodynamic study of the retention of anti-inflammatory 2-arylpropionic acid derivatives on a heat-resistive stationary phase: Application of HTLC approach for pharmaceutical and biological analysis

A study of the retention behavior of four frequently prescribed anti-inflammatory 2-arylpropionic acid derivatives on a reversed-phase thermostable stationary phase was conducted. Extra-thermodynamic investigations were carried out over the temperature range of 303–338 K. A modified van’t Hoff analysis was applied to assess the enthalpy, entropy, and Gibb’s free energy changes that take place during the mass transfer from the mobile phase to the stationary phase. It has been proven that enthalpy–entropy compensation exists as an extra-thermodynamic relationship. The effect of molecular structures of the investigated drugs on thermodynamic and retention behaviors was also explored. A validated high-temperature liquid chromatography method was established for the separation and analysis of ketoprofen, naproxen, diclofenac, and ibuprofen in pharmaceutical formulations and human urine with %recoveries within the range of 90.1–105.6 % and standard deviation not exceeding ±4.1% in all cases. The developed method greenness was positively assessed by the analytical eco-scale score tool.

Antiferromagnetic Order and Spin-Canting Transition in the Corrugated Square Net Compound Cu3(TeO4)(SO4)·H2O.

Strongly correlated electrons in layered perovskite structures have been the birthplace of high-temperature superconductivity, spin liquids, and quantum criticality. Specifically, the cuprate materials with layered structures made of corner-sharing square-planar CuO4 units have been intensely studied due to their Mott insulating ground state, which leads to high-temperature superconductivity upon doping. Identifying new compounds with similar lattice and electronic structures has become a challenge in solid-state chemistry. Here, we report the hydrothermal crystal growth of a new copper tellurite sulfate, Cu3(TeO4)(SO4)·H2O, a promising alternative to layered perovskites. The orthorhombic phase (space group Pnma) is made of corrugated layers of corner-sharing CuO4 square-planar units that are edge-shared with TeO4 units. The layers are linked by slabs of corner-sharing CuO4 and SO4. Using both the bond valence sum analysis and magnetization data, we find purely Cu2+ ions within the layers but a mixed valence of Cu2+/Cu+ between the layers. Cu3(TeO4)(SO4)·H2O undergoes an antiferromagnetic transition at TN = 67 K marked by a peak in the magnetic susceptibility. Upon further cooling, a spin-canting transition occurs at T* = 12 K, evidenced by a kink in the heat capacity. The spin-canting transition is explained on the basis of a J1-J2 model of magnetic interactions, which is consistent with the slightly different in-plane superexchange paths. We present Cu3(TeO4)(SO4)·H2O as a promising platform for the future doping and strain experiments that could tune the Mott insulating ground state into superconducting or spin liquid states.

Materials for High Temperature Liquid Lead Storage for Concentrated Solar Power (CSP) Air Tower Systems.

Today the technical limit for solar towers is represented by the temperature that can be reached with current accumulation and exchange fluids (molten salts are generally adopted and the max temperatures are generally below 600 °C), even if other solutions have been suggested that reach 800 °C. An innovative solution based on liquid lead has been proposed in an ongoing experimental project named Nextower. The Nextower project aims to improve current technologies of the solar sector by transferring experience, originally consolidated in the field of nuclear plants, to accumulate heat at higher temperatures (T = 850–900 °C) through the use of liquid lead heat exchangers. The adoption of molten lead as a heat exchange fluid poses important criticalities of both corrosion and creep resistance, due to the temperatures and structural stresses reached during service. Liquid lead corrosion issues and solutions in addition to creep-resistant material selection are discussed. The experimental activities focused on technical solutions adopted to overcome these problems in terms of the selected materials and technologies. Corrosion laboratory tests have been designed in order to verify if structural 800H steel coated with 6 mm of FeCrAl alloy layers are able to resist the liquid lead attack up to 900 °C and for 1000 h or more. The metallographic results were obtained by mean of scanning electron microscopy with an energy dispersive microprobe confirm that the 800H steel shows no sign of corrosion after the completion of the tests.

Ablation of a Solid Material by High Temperature Liquid Jet Impingement: An Application to Corium Jet Impingement on a Sfr Core-Catcher

Abstract This paper deals with ablation of a solid by a high temperature liquid jet. This phenomenon is a key issue to maintain the vessel integrity during the course of a nuclear reactor severe accident with melting of the core. Depending on the course of such an accident, high temperature corium jets might impinge and ablate the vessel material leading to its potential failure. Since Fukushima Daiichi accident, new mitigation measures are under study. As a designed safety feature of a future European SFR, bearing the purpose of quickly draining of the corium out of the core and protecting the reactor vessel against the attack of molten melt, the in-core corium is relocated via discharge tubes to an in-vessel core-catcher has been planned. The core-catcher design to withstand corium jet impingement demands the knowledge of very complex phenomena such as the dynamics of cavity formation and associated heat transfers. Even studied in the past, no complete data are available concerning the variation of jet parameters and solid structure materials. For a deep understanding of this phenomenon, new tests have been performed using both simulant and prototypical jet and core catcher materials. Part of these tests have been done at University of Lorraine using hot liquid water impinging on transparent ice block allowing for the visualizations of the cavity formation. Other tests have been performed in Karlsruhe Institute of Technology using liquid steel impinging on steel block.

The intimate relationship between structural relaxation and the energy landscape of monatomic liquid metals

The characteristic property of a liquid, discriminating it from a solid, is its fluidity, which can be expressed by a velocity field. The reaction of the velocity field on forces is enshrined in the transport parameter viscosity. In contrast, a solid reacts to forces elastically through a displacement field, the particles are trapped in their potential minimum. The flow in a liquid needs enough thermal energy to overcome the changing potential barriers, which is supported through a continuous rearrangement of surrounding particles. Cooling a liquid will decrease the fluidity of a particle and the mobility of the neighbouring particles, resulting in an increase of the viscosity until the system comes to an arrest. This process with a concomitant slowing down of collective particle rearrangements might already start deep inside the liquid state. The idea of the potential energy landscape provides an attractive picture for these dramatic changes. However, despite the appealing idea there is a scarcity of quantitative assessments, in particular, when it comes to experimental studies. Here we present results on a monatomic liquid metal through a combination of ab initio molecular dynamics, neutron spectroscopy and inelastic x-ray scattering. We investigated the collective dynamics of liquid aluminium to reveal the changes in dynamics when the high temperature liquid is cooled towards solidification. The results demonstrate the main signatures of the energy landscape picture, a reduction in the internal atomic structural energy, a transition to a stretched relaxation process and a deviation from the high-temperature Arrhenius behavior of the relaxation time. All changes occur in the same temperature range at about 1.4 cdot T_{melting}, which can be regarded as the temperature when the liquid aluminium enters the landscape influenced phase and enters a more viscous liquid state towards solidification. The similarity in dynamics with other monatomic liquid metals suggests a universal dynamic crossover above the melting point.

Investigating Molten Sodium Batteries with an Aqueous Catholyte

High-temperature liquid sodium batteries (e.g. sodium-sulfur) are a well-established technology for large-scale grid storage. Combining the molten sodium anode with an aqueous iodine cathode overcomes the problems of thermal loses and sealing by reducing the operating temperature to about 100°C.This leads to higher cost efficiency, energy density and a simplified cell design. Due to their sustainability and high efficiency, which is comparable to Li-Ion –batteries, mid-temperature sodium-iodine batteries are a promising candidate for small and medium scale stationary energy storage applications. Experiments performed by Holzapfel et al. show proof of principle for a current density of 20 mA cm-2 (55mW cm-2) up to a maximum current density of 100 mA cm-2 (180mW cm-2)[1] . The used iodine concenctrations correspond to 405 Wh l-1 on catholyte basis or a very high specific energy of 198 Wh kg-1 including anolyte and catholyte. Sodium-iodine batteries have the ability to meet the growing demand of short-term energy storage caused by the integration of renewable energy sources into the power grid.Although these batteries are theoretically described in literature, the detailed processes inside the battery are not well understood[2] . Quantities like initial species concentrations, C-rate, cell design and cathode geometry have large impacts on the overall battery performance. Simulations have to be undertaken because experimental studies are limited to macroscopic quantities like external current or electric potential. Here we present a fully resolved 3D simulation model developed from a LIB simulation tool[3] to gain insight into microstructural processes inside the battery.The proposed spatially resolved three-dimensional model takes charge and mass transport, heterogeneous and homogeneous reactions as well as the electrochemical processes into account. In this contribution, we present recent investigations about cell design, cathode material structures and the electrolyte composition carried out with a new 3D simulation model.A deeper understanding of these processes is inevitable for enhancing the battery performance by choosing the optimal above-mentioned quantities. Figure 1

Green method development approach of superheated water liquid chromatography for separation and trace determination of non-steroidal anti-inflammatory compounds in pharmaceutical and water samples and their extraction

Non-steroidal anti-inflammatory drugs (NSAIDs) are pharmaceutical compounds with anti-inflammatory, analgesic, and antipyretic effects. Herein, a simple and rapid high-temperature liquid chromatography and superheated water chromatography method was developed and validated for the trace determination of NSAID residues of ketoprofen, naproxen, sodium diclofenac, and ibuprofen in water samples. The NSAIDs were separated in less than five minutes using buffered distilled water as the mobile phase and ODS Zirconia RP-C18 column as the stationary phase. Linearity was observed in the van’t Hoff plots of the tested drugs by employing a low acetonitrile percentage (20% ACN) in the mobile phase, without any significant changes in their retention mechanisms. However, nonlinear van’t Hoff plots were obtained for the superheated water chromatography data of the tested drugs because of significant changes in their retention factors, transition stage of the stationary phase, or the mobile phase properties. The limits of detection for ketoprofen, naproxen, sodium diclofenac, and ibuprofen were 14, 2, 4.2, and 32 µg L −1 , respectively, and their limits of quantification were 44, 8, 12, and 98 µg L −1 , respectively. The accuracy and precision parameters were determined for selected drugs, where the relative standard deviations were in the range of ± 0.2179–2.6741%. In addition, these conditions were employed for the removal of NSAIDs from the water samples using carbon nanotubes. The proposed system was applied for the separation and analyses of drugs in water and pharmaceutical samples, and acceptable recoveries of 90.48–98.15% for the water samples and 99.9–100.08% for the pharmaceutical samples were obtained.

Investigation on the Solubility of the Antidepressant Drug Escitalopram in Subcritical Water

Escitalopram (ESC), the S-enantiomer of citalopram, is a selective serotonin reuptake inhibitor. Escitalopram is widely used to treat panic disorder, depression, obsessive compulsive disorder, and social anxiety disorder. The main goal of this present research is to determine the aqueous solubility of ESC at temperatures ranging from 298 to 473 K and a pressure of 5.0 MPa. ESC solubility increased significantly from 1.08 × 10–3 to 59.88 × 10–3 (mole fraction) when the temperature was raised from 298 to 473 K. This is a 55-fold enhancement. A mathematical model was developed based on our experimental solubility data. The model was used to successfully predict the solubility of ESC in subcritical water. Furthermore, experimental data were correlated using a modified Apelblat equation. The apparent thermodynamic analysis including apparent dissolution standard enthalpy (ΔsolH) and apparent dissolution standard entropy (ΔsolS) were calculated. Thermodynamic property calculations showed that the process is endothermic ΔsolH > 0, and the ΔsolS values were relatively high. Spectroscopic analyses revealed that ESC was stable in subcritical water at temperatures up to 473 K. The enhanced solubility of ESC in subcritical water enabled us to use high-temperature liquid chromatography to separate this antidepressant drug.

Surface functionalization of acetylene black by high temperature liquid phase oxidation and a method for the evaluation of acidic functional groups using the heterocoagulation of a Au colloid

Surface functionalization of acetylene black by high temperature liquid phase oxidation and a method for the evaluation of acidic functional groups using the heterocoagulation of a Au colloid

Investigation on fretting wear behavior of 2.25Cr–1Mo tube in water at various temperatures

Heat transfer tubes are subjected to cyclic and direct contact under high temperature liquid conditions due to flow-induced vibration. The influence of water temperatures (25, 60, and 95 °C) and loads (10, 20, and 30 N) on the fretting wear behavior of 2.25Cr–1Mo tube against Gr5C12 rod was investigated. Results indicate that the fretting regime changes from gross slip to partial slip as the load increases from 10 N to 30 N. The fretting regime remains unchanged as the water temperature increases from 25 °C to 95 °C. The fretting regime is more related to load than water temperature, implying that the water temperature and load play different roles in the fretting wear process. The coefficient of friction (COF), wear morphology, wear volume, and wear rate show an evident dependence on load and water temperature, while the COF has a significant relationship with the load. The effect of micro-pitting may be ignored due to the material removal from the original surface and formation of wear debris layer (WDL) in the gross slip regime.

Development of a Multiphase Beryllium Equation of State and Physics-based Variations.

We construct a family of beryllium (Be) multiphase equation of state (EOS) models that consists of a baseline ("optimal") EOS and variations on the baseline to account for physics-based uncertainties. The Be baseline EOS is constructed to reproduce a set of self-consistent data and theory including known phase boundaries, the principal Hugoniot, isobars, and isotherms from diamond-anvil cell experiments. Three phases are considered, including the known hexagonal closed-packed (hcp) phase, the liquid, and the theoretically predicted high-pressure body-centered cubic (bcc) phase. Since both the high-temperature liquid and high-pressure bcc phases lack any experimental data, we carry out ab initio density functional theory (DFT) calculations to obtain new information about the EOS properties for these two regions. At extremely high temperature conditions (>87 eV), DFT-based quantum molecular dynamics simulations are performed for multiple liquid densities using the state-of-the-art Spectral Quadrature methodology in order to validate our selected models for the ion- and electron-thermal free energies of the liquid. We have also performed DFT simulations of hcp and bcc with different exchange-correlation functionals to examine their impact on bcc compressibility, which bound the hcp-bcc transition pressure to within 4 ± 0.5 Mbar. Our baseline EOS predicts the first density maximum along the Hugoniot to be 4.4-fold in compression, while the hcp-bcc-liquid triple-point pressure is predicted to be at 2.25 Mbar. In addition to the baseline EOS, we have generated eight variations to accommodate multiple sources of potential uncertainties such as (1) the choice of free-energy models, (2) differences in theoretical treatments, (3) experimental uncertainties, and (4) lack of information. These variations are designed to provide a reasonable representation of nonstatistical uncertainties for the Be EOS and may be used to assess its sensitivity to different inertial-confinement fusion capsule designs.

A study on sodium - the fast breeder reactor coolant

Sodium, the second alkali metal in the first group of periodic table is highly chemically reactive. Sodium is widely used in pharmaceutical industries to manufacture lifesaving medicines. Liquid sodium is an excellent reducing agent and heat transport medium, which makes it an important industrial material. The application of this element in liquid form at high temperature as a coolant in fast breeder nuclear reactors necessitated development of sodium technology. Physical, chemical and nuclear properties of sodium led to the choice of sodium as the universally accepted fast breeder reactor (FBR) coolant. The manufacturing of sodium is by electrolysis process. The design and manufacturing requirements of high temperature liquid sodium system components are successfully addressed. Special type of sensors needed for high temperature liquid sodium system are specifically designed and developed. Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam is involved in the development of sodium technology in India. Sodium technology is matured to an extent and around twenty FBRs with sodium as the coolant were constructed, commissioned and successfully operated all over the world. Five sodium cooled fast reactors are currently in operation including fast breeder test reactor (FBTR) in India. Prototype fast breeder reactor (PFBR) is in the advanced stage of commissioning at Kalpakkam. This review paper explains the choice of sodium as FBR coolant and gives highlights on the research and development took place in sodium technology all over the world especially in India with an aim to give an exposure to this technology to the academic community.

Numerical investigation on the water vaporization during semi dry flue gas desulfurization in a three-dimensional spouted bed

Gas–solid two-phase flow and water vaporization processes tend to have a significant impact on the efficiency of flue gas desulfurization with a powder-particle spouted bed. According to the numerical results obtained in this study, the 2D spouted bed developed a classic three-area flow, and the 3D spouted bed entered into a bubbling-like state. The gas and particles flowed in the opposite direction at the junction of the cone and cylinder. The water vaporization rate was higher at the junction of the spout area and the annulus area, lower at the center of the spout area, and the lowest in the annulus area of the 3D spouted bed. Furthermore, it was found that a larger gas velocity, a higher liquid temperature, and a lower gas humidity leads to a higher water vaporization process.

High-temperature and high-pressure density and liquid–vapor phase transition properties of methyl octanoate as main biofuel component

Thermodynamic properties of compressed fuels as density at liquids phase (PρT data) and two liquids-gas phases as saturated pressure, density, and temperature (PS,ρS,TS) are extremely important for engine performance as well as the transportation and storage of fuels. In this work single – and two–phase PρT data and liquid + gas phase equilibrium properties (PS,TS,ρS) of methyl octanoate (caprylate) as one of the key components of biofuels have been studied. The measurements were performed along 15 liquid and vapor isochores between (44.7 and 832.0) kg·m−3 over a temperature range from (298 to 438) K at pressures up to 17.33 MPa using a constant-volume piezometer technique. The study was concentrated in the two-phase region to accurately determine vapor-pressures and in the immediate vicinity of the phase-transition temperatures to precisely determine the phase boundary properties (PS,ρS,TS) on the liquid + gas equilibrium curve. In the low temperature range (far from the critical point) where the values of vapor-pressure are negligible small (<1 kPa, approximately at temperatures below 350 K), the saturated vapor phase of methyl octanoate was considered as ideal gas with volume of VG=RT/PS and ΔVLG≈VG=RT/PS, where the saturated liquid volume can be neglected, VG>>VL. This approach was used to simplify the calculation of the thermodynamic properties of methyl octanoate at saturation.