Temperature Liquid Phase Research Articles

1,8-Diazabicyclo[5.4.0]undec-7-ene as Cyclic Ether Electrolyte Polymerization Inhibition for Wide-Temperature-Range High-Rate Lithium-ion Batteries.

1,3-Dioxolane (DOL), with its broad liquid phase temperature window and low Li+-solvent binding energy, stands out as an ideal solvent candidate for the wide-temperature and high-rate electrolytes. Unfortunately, DOL is susceptible to undergo ring-opening polymerization under common lithium salts, which markedly retards the reaction kinetics. This work introduces the organic basic additive 1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU) to effectively suppress the polymerization, thus achieving compatibility between LiFSI, LiDFOB lithium salts, and DOL. Furthermore, density functional theory (DFT) calculations are utilized to elucidate the underlying mechanisms of DOL polymerization and to clarify how DBU inhibits its polymerization. The resulting electrolyte, devoid of polymer chain formation, forms a weak solvation structure rich in anions, which demonstrates rapid ion transport kinetics in the bulk electrolyte and excellent electrochemical stability at the electrolyte-electrode interfaces (EEIs) simultaneously. When applied to the LiFePO4||graphite full cell, it exhibits exceptional wide-temperature and high-rate performance, with specific capacities reaching 101.2 mAh g -1 at room temperature (20 C), 36.9 mAh g-1 at -40 °C (0.5 C), and 118.0 mAh g-1 at 60 °C (20 C). This study significantly guides the development of wide-temperature, high-rate electrolytes.

Reparameterization of the mW model to accurately predict the experimental phase diagram of methane hydrate.

Due to their high computational efficiency, the coarse-grained water models are of particular importance for practical molecular simulations of gas hydrates. In these models, the mW model is successfully used to study many thermodynamics and dynamics of methane hydrate. Yet, despite several decades of intense research, the mW model is still found to overestimate the melting temperature of methane hydrate. We here employ the minimum mean squared error estimation to revisit the key parameter of the mW model, which determines the strength of the tetrahedral angle of the water system. Relying on the free energy calculations, we first estimate the chemical potentials of water in the liquid phase for temperatures at which methane hydrate forms. We then turn to the mean squared error to describe the chemical potential deviation between the mW model and the TIP4P/ice model (the latter could reproduce the experimental phase diagram of methane hydrate). By minimizing the mean squared error, we finally have an optimized parameter for the mW model. In this part, we also discuss the pressure effect on such reparameterization procedure. Moreover, relying on the direct coexistence method, the melting temperature determined using the reparameterized mW model is found to be consistent with the experimental data. This strategy provides a means to improve the coarse-grained model to match the experimental observations for temperatures in the range of interest.

Enhancing strength and ductility of CuCrZr high-conductivity alloy via lamellar heterostructures on grain boundaries

Heterogeneous lamellar structure materials have attracted extensive attention due to their exceptional strength and ductility. In this study, Y element was introduced into CuCrZr alloys to adjust the liquid phase formation temperature of the CuZrY phase during the solution annealing process. By employing cold rolling deformation prior to annealing to elongate the grains, the liquid phase was promoted to wet the elongated grain boundaries during the annealing process, ultimately forming lamellar CuZrY heterostructures distributed along the grain boundaries. The heterogeneous lamellar structure, the grain boundary distribution characteristics, and the effect of Y on stacking fault energy enhanced the hetero-deformation induced working hardening, thereby improving both the strength and ductility of the CuCrZrY alloy. Besides, the investigated CuCrZrY alloy achieved an excellent combination of tensile strength, uniform elongation, electrical conductivity and thermal conductivity, with values of 527 MPa, 10.66%, 83% IACS and 335.5 W/(m·K), respectively. Therefore, the method of controlling liquid phase temperature through composition adjustment and liquid phase infiltration path through grain deformation offers new possibilities for the design of heterogeneous lamellar structure materials.

Ti6Al4V alloy with diamond particle-reinforced Cu-based coatings: Microstructure and tribological performance

To enhance the surface wear resistance of the Ti6Al4V alloy, diamond particles-reinforced Cu-based composite coatings (D500/D1000/D2000 coating: 500/1000/2000 mesh diamond: Cu-based alloy powder = 1:30 (wt%)) were fabricated by vacuum cladding. Cu-based alloys with liquid phase temperatures lower than the phase transition temperature of Ti6Al4V alloys were employed as cladding materials to avoid performance deterioration of Ti6Al4V substrates. The microstructure, mechanical properties, and dry-sliding tribological properties of the Cu-based composite coatings have been investigated systematically. The Cu-based composite coatings are composed of the ductile intermetallic compounds Ti3Sn and SnTi2 as the metal matrix, the hard and brittle intermetallic compounds CuTi, CuTi2, Ti(Cu, Al)2 and CuSn3Ti5, in situ generated TiC and the directly introduced diamond particle as the reinforced phases. In addition, a TiC hard phase protective layer was formed around the diamond particles, which retained the original properties of the diamond. The hardness of diamond particles-reinforced Cu-based composite coatings is much higher than that of the Ti6Al4V. Among them, the D2000 coating possesses the highest microhardness. The average Vickers hardness (HV0.5) on the coating surface and nanoindentation hardness (H) on the coating cross-section (the middle part without diamond particles) of the D2000 coating are 1329.8 HV0.5 and 16.87 GPa), which are 4–5 times higher than that of the Ti6Al4V substrate (333 HV0.5 and 3.37 GPa). Nevertheless, the D2000 coating (wear rate of 50.75 ×10−5 mm3/Nm) demonstrates slightly inferior tribological performance compared to the D500 coating. The wear rate of the latter is approximately 13.37 × 10−5 mm3/Nm, which is only 1/5.6 of the substrate (75.67 ×10−5 mm3/Nm). The larger the diamond particle size, the more the diamond serves as a bearing capacity support point to prevent the hard WC ball from further ploughing into the composite coating, and the better the wear resistance of the coating. Notably, D500 coating with excellent wear resistance has the potential for application in various fields of the machinery industry, marine engineering, and aerospace.

Kinetics of methane hydrate formation in a 1200 ml unstirred reactor for natural gas storage

Solidified natural gas (SNG) technology via clathrate hydrates, enhanced by promoters such as tetrahydrofuran (THF), promises large-scale natural gas storage due to its high volumetric capacity and mild storage conditions. Despite its potential for industrial scale-up, limited research exists on methane hydrate formation behaviors in large reactors (>1000 cm3), which is crucial for evaluating practical storage performance. In this study, methane hydrate formation kinetics were investigated in a scaled-up unstirred reactor (1200 cm3) at 288.15 K and 283.15 K, and 5.0 MPa. Methane uptake, system pressure, gas and liquid phase temperatures, and hydrate morphologies were analyzed to describe the dynamic hydrate formation process. Results reveal three effects of increased reactor size in contrast to smaller reactors: (i) heterogeneous distribution of THF-rich and methane-rich hydrates; (ii) hydrate bulk show a hollow inner structure with a cavity due to the wall-climbing behavior of hydrate growth; (iii) optimal THF concentration no longer always agrees with stoichiometric 5.56 mol%, which is case-dependent. These effects are attributed to higher diffusion resistances for methane molecules and more intensive heat accumulation. These findings provide some insight into the kinetics of methane hydrate formation in industrial reactors, which is critical for the commercialization of SNG technology.

Room temperature synthesis of BaTiO3 nanoparticles using titanium bis(ammonium lactato) dihydroxide

BaTiO3, known for its exceptional ferroelectric properties, is extensively applied in multi-layer ceramics capacitors (MLCCs). Achieving reliable, high-performance MLCCs requires sophisticated ceramics processes, notably in synthesizing submicron-order BaTiO3 powder with a narrow size distribution. Among various synthesis methods explored for submicron-size BaTiO3 powder, room temperature liquid-phase synthesis is most desirable due to its cost-effectiveness and large batch availability. In this study, we propose a synthesis method for obtaining BaTiO3 nanopowder at room temperature using titanium bis(ammonium lactato) dihydroxide and Ba(OH)2·8H2O as starting materials, reacted in tert-butylamine with NaOH and ethanol. The resulting powder, exhibiting a cubic phase of BaTiO3 with an average particle size of 35.8 nm, was obtained after a 7-day reaction at room temperature. Characterization involved X-ray diffraction, differential thermal analysis‒thermogravimetry, and scanning electron microscopy. Subsequently, the powder was used to sinter a BaTiO3 ceramic, whose dielectric performance was then evaluated.

Freeze-Vulnerable Plastic Crystal to Cryogenic Liquid Electrolyte for Lithium Batteries by Deep Freezing-Point Depression.

Low-Tf solvents (Tf = freezing point) are considered and employed for low-temperature lithium-ion battery (LIB) electrolytes to keep electrolytes in the liquid phase at low temperatures. Unfortunately, Tf is synchronized with Tb (boiling point) so low Tf brings Tb down and therefore discourages the thermal stability of electrolytes using low-Tf solvents. In this work, 1) the hot wing of LIB-working temperature by employing a high-Tb (inevitably high-Tf) solvent and 2) the cold wing by using a significant Tf depression is secured. Sulfolane is employed as the high-Tf (therefore, high-Tb) and high-Kf (Kf = cryoscopic constant) solvent since its mesomorphic state between solid and liquid. That abnormally and significantly decreases the enthalpy of fusion, and resultantly grants extremely high Kf at 66.4Km-1. By employing sulfolane with 2m lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), the liquid-phase temperature window down to <-80°C for the cold wing and simultaneously guaranteed its flash point at >+150°C for the hot wing is successfully extended. LIB cells with lithium iron phosphate and lithium metal worked in a good stand with 2m LiTFSI/sulfolane at room temperature, -30°C as an ambient cold, -74°C as a deep cold, and +80°C as a deep hot.

Fabrication of Na+-Conducting Ionic Liquids Na[((FSO2)2n) x ((CF3SO2)(FSO2)N)1-X ], and Its Physical and Electrochemical Properties

To achieve low-carbon society in near future, it’s imperative to research and develop high-performance and low-cost batteries. Therefore, sodium-ion batteries (SIBs) are attracting attention owing to their possibility to be composed of elements with no resource scarcity and low cost.To solve the challenge of low energy density in SIBs, it is essential to focus on developing electrodes of the 4V to 5V class. Simultaneously, electrolytes with wide electrochemical window are crucial from in terms of electrolyte decomposition at high operating voltages. Molten salt electrolytes exhibit relatively high ionic conductivity and electrochemical stability. On the other hands, there is an issue that the electrolyte must be heated to a high temperature to maintain molten state of the electrolytes. In this study, with the goal of expanding the melting temperature range of molten salt electrolytes, we precisely mixed relatively low-melting sodium salts Na(FSO2)2N (NaFSA) and Na(CF3SO2)(FSO2)N (NaFTA) and found a composition with a melting point below 100 ℃. As a result, we successfully fabricated novel single-sodium cationic salt ionic liquid. In this presentation, we will report on its bulk properties and electrochemical characteristics. All mixed sodium salts were mixed NaFSA and NaFTA in each molar ratio and stirred during gradually cooling after uniformly melting at 170 ℃ in Ar-filled grove box. The thermal properties of the mixed sodium salts were evaluated by differential scanning calorimetry (DSC). The samples were stored at room temperature for 2~3 days to reach equilibrium state, and then sealed in a high-pressure SUS pan. Ionic conductivity (σ) of the mixed sodium salts were also measured from 60 ℃ to 135 ℃ at each temperature. Symmetrical cells were constructed by put the mixed sodium salt between two SUS or sodium metal electrodes. Ionic conductivity of mixed sodium salts was evaluated by electrochemical impedance spectroscopy (EIS) with SUS electrodes symmetric cells. Na+ transference number was measured by potentiostatic polarization and EIS with sodium metal symmetric cells at 90℃. The binary phase diagram of NaFSA and NaFTA were shown in Fig.1. In the NaFTA-rich composition range (0.1 < x < 0.4), the phase diagram resembles a simple eutectic phase diagram, while, in the NaFTA-rich composition range (0.5 < x < 0.9), the mixed sodium salts exhibited pseudo-single-phase behavior, and the lowest liquid-phase transition temperature (T L) was observed at 90℃ of Na[(FSA)0.8(FTA)0.2].(1) Additionally, in this composition range, glass transition points (T g) were also confirmed, indicating the supercooled behavior.The Arrhenius plot of the ionic conductivity (σ) for Na[(FSA)0.8(FTA)0.2] was shown in Fig.2. At the T L around 90℃, σ was observed to 0.69 mS cm-1. This is attributed to the strong interactions between Na+ and anion in the absence of solvents, causing high viscosity and decreasing mobility. Below the T L, there was no remarkable decrease in σ and Nyquist plots remained non-divergent to 55℃, allowing for the attribution of σ. Moreover, below the T L, the glass transition and crystallization of Na[(FSA)0.8(FTA)0.2] were not observed. The temperature dependence of σ was analyzed by the Vogel-Fulcher-Tamman (VFT) equation.(2) In addition, the σ(T g) at the observed T g from DSC were calculated by VFT equation. Also, the decoupling index (R τ), representing the ratio of ionic conductive relaxation time (τ σ) to structural relaxation time (τ s), were calculated.(3) The value of logR τ value for Na[(FSA)0.8(FTA)0.2] was -0.62 and the low value indicates that τ s is coupled with τ σ.To investigate the Na+ conduction behavior in Na[(FSA)0.8(FTA)0.2], chronoamperograms with an applied potential of 500 mV to the sodium metal symmetric cells were shown in Fig.3(a). Fig.3(b) shows Nyquist plots before and after direct current polarization. The steady current was observed after 8h. Furthermore, there was slightly changes of Nyquist plots before and after direct current (DC) polarization, stable interface between sodium metal and Na[(FSA)0.8(FTA)0.2] was also confirmed. The Na+ transference Number (t Na+) in the Na[(FSA)0.8(FTA)0.2] was estimated to be 0.86. Tatara et al. reported the t Na+ of 0.18 in the 1M NaPF6/PC+0.5vol% FEC.(4) Since molten salts consisting of only cations and anions should not be occurred concentration polarization, it exhibited a considerably higher t Na+ in Na[(FSA)0.8(FTA)0.2] compared to the t Na+ in dilute non-aqueous sodium electrolyte. In the presentation, we will discuss the cycle characteristics obtained by constant current charge-discharge tests of both half-cell and full-cell configurations using generic positive and negative electrode materials.(1) K. Kubota et al., J. Chem. Eng. Data, 55, No. 9, 2010, 3142–3146.(2) H. Vogel., Phys. Z. 1921, 22, 645.(3) C. A. Angell, Annu. Rev. Phys. Chem. 1992, 43, 693.(4) R. Tatara et al., Electrochemistry, 89(6), 2021, 590–596. Figure 1

Experimental Study on Preparation of Inorganic Fibers from Circulating Fluidized Bed Boilers Ash.

The ash generated by Circulating Fluidized Bed (CFB) boilers is featured by its looseness and porosity, low content of glassy substances, and high contents of calcium (Ca) and sulfur (S), thus resulting in a low comprehensive utilization rate. Currently, the predominant treatment approach for CFB ash and slag is stacking, which may give rise to issues like environmental pollution. In this paper, CFB ash (with a CaO content of 7.64% and an SO3 content of 1.77%) was used as the main raw material. The high-temperature melting characteristics, viscosity-temperature characteristics, and initial crystallization temperature of samples with different acidity coefficients were investigated. The final drawing temperature range of the samples was determined, and mechanical property tests were conducted on the prepared inorganic fibers. The results show that the addition of dolomite powder has a significant reducing effect on the complete liquid phase temperature. The final drawing temperatures of the samples with different acidity coefficients range as follows: 1270-1318 °C; 1272-1351 °C; 1250-1372 °C; 1280-1380 °C; 1300-1382 °C; and 1310-1384 °C. The drawing temperature of this system is slightly lower than that of basalt fibers. Based on the test results of the mechanical properties of inorganic fibers, the Young's modulus of the inorganic fibers prepared through the experiment lies between 55 GPa and 74 GPa, which basically meets the performance requirements of inorganic fibers. Consequently, the method of preparing inorganic fibers by using CFB ash and dolomite powder is entirely feasible.

Li2O addition as a means of achieving low-temperature densification of SiC ceramic

In order to achieve low-temperature densification of SiC ceramic, β-SiC nanopowder was doped with Li2O together with Y2O3–Al2O3–MgO as sintering aids, and then spark plasma sintered at temperatures ranging from 1450 °C to 1600 °C for 30 min under 30 MPa pressure in argon. The densities, microstructures and mechanical properties of SiC ceramics were systematically investigated, in comparison to the counterparts sintered with Y2O3–Al2O3–MgO additives. Since Li2O has a low melting point, Li2O addition effectively decreased the formation temperature of liquid secondary phase, enabling SiC ceramics to obtain higher density and lower porosity after low-temperature sintering (T ≤ 1550 °C). Besides, Li2O addition was found to decrease the viscosity of liquid phase and enhance grain growth of SiC through dissolution-reprecipitation process. When sintered at 1550 °C, Li2O addition led to a remarkable increase of density from 3.03 g/cm3 to 3.21 g/cm3 for SiC ceramic. Meanwhile, the SiC ceramic with Li2O addition exhibited a high Vickers hardness of 22.75 ± 0.35 GPa and a good fracture toughness of 3.83 ± 0.27 MPa m1/2. The research results are expected to benefit the low-cost fabrication of SiC ceramics based on pressure-assisted sintering and alleviate the thermal damage of SiC fiber in hot-pressed SiCf/SiC composites.

Application Of Two Dye Two-Color Laser-Induced Fluorescence Spectroscopy On Droplets Of Green Solvent Mixtures Containing Water And Ethanol

In order to reach a higher sustainability, the utilization of green solvents is decisive in many technical applications. Water and ethanol substitute more complex solvents, showing advantages like ecological manufacturing, reusability or biodegradation. Both liquids are found in various industrial areas, ranging from a use as additives in biofuels, coolants or solvents for extraction in pharmaceutical, medical or food industries. Regarding these industrial processes, important variables are the liquid phase temperature and the composition in binary fluids. The focus of this work is two dye two-color laser induced fluorescence (2c-LIF) measurements in ethanol, water and their mixtures. Liquid phase thermometry via 2c LIF requires a selection of suitable fluorescence dyes regarding solubility, temperature sensitivity and the interaction among the dyes themselves. A mixture of a temperature sensitive and a temperature insensitive dye is used in order to reach a large change in signal ratio for thermometry. In this work, two dyes – fluorescein disodium (FL) and sulforhodamine 101 (SRh), as proposed by Chaze et al. (Chaze et al. 2016) – are analyzed regarding their absorption and emission behavior in various ethanol/water mixtures, which are examples of "green solvents". The absorption spectra of the dissolved dye mixture are measured with a spectrophotometer at temperatures from 293 K to 343 K. Information on the temperature dependent absorption of the single dyes and reabsorption effects in ethanol/water mixtures is obtained. Additionally, the fluorescence of the mixtures is analyzed spectrally and by an imaging system. Therefore, a fiber coupled spectrometer and a system with two sCMOS cameras equipped with a long distance (LD) microscope are applied for simultaneous detection of the signal of tempered solutions a monodisperse droplet chain. A study of small droplets with sizes below 50 μm are evaluated and the limit of the spectral detection system is determined and discussed. The application of the measurement technique to several solvent mixtures is investigated. Additionally, an application for composition investigations of binary water/ethanol droplets via 3c-LIF is proposed.

Solidification path and precipitation mechanism of a Ni-Cr-co-Mo based heat-resistant alloy

The solidification path and precipitation mechanism of the C-HRA-3 Ni-Cr-Co-Mo-based heat-resistant alloy are investigated by methods such as differential scanning calorimetry analysis, in-situ observations, quenching experiments, and scanning transmission electron microscopy. The results confirm that the primary solidification precipitates in the center of the C-HRA-3 alloy VAR ingot consist of Ti(C,N), M6C-M23C6 symbiotic phases, Ti(C,N)-M6C-M23C6 symbiotic phases and surrounding dispersed M6C and M23C6 carbides. The precipitation temperatures for Ti(C,N), M6C, and M23C6 are 1310 °C, 1280 °C, and 1230 °C, respectively. The C-HRA-3 alloy exhibits a wide solidification temperature range of 176 °C (1390 °C ∼ 1214 °C). Within 1390 °C ∼ 1355 °C, the γ phase grows vigorously, accompanied by a significant reduction in the fraction of liquid phase. At 1355 °C ∼ 1214 °C, the decrease in liquid phase fraction slows down, accompanied by significant enrichment of Mo, Cr, C and Ti elements. There is a clear functional relationship between the liquid phase percentage and temperature. M6C carbides undergo two heterogeneous nucleation mechanisms in the liquid phase. Due to the degradation of M6C carbides discharging Cr and C atoms, M23C6 carbides form at their edge. Dispersed M6C and M23C6 carbides nucleate at misfit dislocations around the symbiotic phases. Appropriately reducing the cooling rate during the stage above the precipitation temperature and increasing the cooling rate below the precipitation temperature can significantly reduce the volume percentage and size of the symbiotic phases.

FEATURES OF PHASE DIAGRAMS OF A TWO-FREQUENCY PENDULUM IN JAN-TELLER POTENTIAL AND HEAT CAPACITY OF WATER

A simulation of rotational vibrations of a water molecule was carried out using a model of a two-frequency pendulum in a simple Jahn–Teller potential (JTP), which has a minimum potential at a certain angle of deviation of the pendulum from the axis (the bending angle of the intermolecular hydrogen bond of the water molecule). It has been established that at low initial speeds for a given potential a new type of oscillations is observed - transverse oscillations of the pendulum inside the circular gutter JTP, at medium speeds - two-frequency independent oscillations (IO) along two axes, and at large ones - ellipse-like oscillations (ELO) at a single frequency. The work examines phase diagrams (PD) and mixed PD (MPD) in two coordinates for these two-dimensional oscillations. A significant difference between these diagrams in the JTP and standard PD is shown. The appearance of additional ellipses, loops and waves on the PD due to the appearance of transverse vibrations in the nuclear fuel gutter was discovered. To obtain ellipses in phase diagrams from all transverse oscillations of the pendulum, it is proposed to construct a PD versus radius (PDR) for the oscillation trajectory. It is shown that ellipses on the PDR for transverse oscillations of the pendulum are clearly observed at low initial speeds, but for medium and high speeds the transverse part of speed is not independently distinguished from the total speed. The presence of stable transverse vibrations in the JTP gutter for rotational vibrations of hydrogen atoms of water molecules around the axes of intermolecular bonds can be considered as new degrees of freedom for its new collectivized transverse vibrations in this potential. Their existence may lead to an explanation for the contribution of these types of oscillations to the anomalously large heat capacity of water in the liquid phase. However, for the presence of such new degrees of freedom for transverse vibrations of water molecules, it is necessary that their vibrations always take place in the region of “small” velocities - in the JTP gutter. To do this, it is necessary to increase this range of vibrations so that the maximum value of the potential on the axis of the intermolecular bond would be large. This should ensure the existence of transverse rotational oscillations in the JTP gutter for water molecules in all liquid phase temperatures.

Energy Storage in Lightweight Aggregate and Pervious Concrete Infused with Phase Change Materials

This study explores the feasibility of utilizing pervious concrete (PC) incorporating diverse lightweight aggregates (LWAs) integrated with phase change materials (PCM) for applications where forced air cooling would be advantageous. The use of such a component provides latent and sensible heat that can cool forced air applications, offsetting ambient temperature increases that occur during the day. Macro- and microencapsulation techniques were used to incorporate inorganic PCM in the PC. The macro-encapsulation technique involved enclosure of PCM within a stable shell prior to addition into the concrete. The microencapsulation technique involved the impregnation of PCM into porous lightweight aggregate. To overcome the PCM reaction with the concrete constituents, an epoxy coating was utilized. The design of the PCM concrete mix and comprehensive laboratory assessment of porosity, water permeability, PCM absorption capacity, compressive strength, and microstructure of the LWAs are detailed. The test results indicate that LWAs have high PCM impregnation rates ranging from 32 % to 57 % by volume. The compressive strengths of PC using LWAs were reduced by 25 % to 65 % when using microencapsulation. The use of microencapsulation was found to reduce the pressure drop under air flow due to the increase in aggregate size as a result of the coating thickness. PCM-PC with a shell thickness of 100 mm, resulted in a pressure drop of less than 100 Pa at a velocity of 0.35 m/s. The use of macro-encapsulated PCM in PC was sensitive to the phase of the PCM, where the liquid phase reduced the compressive strength by 67 %. The failure occurred within the macro-encapsulated PCM at the liquid phase temperatures and at the interface between the encapsulated PCM at solid phase temperatures. The heat transfer provided by the LWA infused PCM when used in a packed aggregate bed or in PC, was shown to match expected latent and sensible heat estimates based on the thermal properties of the materials. This systematic investigation provides valuable insights into LWAs and PCM performance in pervious concrete, offering a comprehensive understanding of their interaction in cooling applications.

Remediation of oil-drilling cuttings by ozonation in a bubble flow reactor

Oil-drilling cuttings (ODCs) are the major wastes generated during oil/gas exploration and extraction. In the present work, a new method based on ozonation is suggested for the remediation of ODCs at ambient conditions, without pre-drying. During the ozonation process, the pressure drop across the gas phase along with the pH, redox potential, and temperature of liquid phase are monitored with the aid of built-in sensors. Occasionally, solid and liquid samples are collected to measure the total organic carbon (TOC) of each phase as a function of time, while the concentration of the total petroleum hydrocarbons (TPH) is measured before and after the completion of treatment. The maximum TOC removal efficiency for the solid phase reached ∼60% and that of TPH ∼ 40% whereas the energy efficiency was ∼ 0.1 kWh/g-TOC. The main mechanisms of ODC remediation are the mass-transfer of organic species from the solid to aqueous phase, and the direct oxidation by dissolved ozone, whereas their synergistic action is reflected in fluctuations of TOC concentration in liquid phase. The TOC removal efficiency of the solid phase increases with the flow rate decreasing, the ozone concentration increasing, and the mass ratio of ODC to seawater (SW) increasing. Ozonation in the liquid phase after its separation from treated ODC proceeds very fast through the direct oxidation by ozone. The process energy efficiency is favoured for low ozone concentration, low gas flow rate, high ODC to SW mass ratio, oxygen as feed gas, and without the addition of sodium dodecyl sulphate (SDS) as surfactant.

Numerical study of phase change heat accumulator with distribution of Hanoi tower-shaped fin

Hanoi tower-shaped fin distribution was proposed to improve the shell-and-tube phase change accumulator's ability for heat storage. Unlike the common annular fin group, the fin spacing of the Hanoi tower-shaped fin distribution is distributed in an arithmetic sequence, the fin length increases in a fixed proportion, and the fin group's overall position changes with the bottommost spacing. In this paper, the effects of no fin, uniform fin distribution, and Hanoi tower-shaped fin distribution on the melting process were compared and analyzed. The single-factor effects of bottommost spacing, spacing tolerance, and length ratio were analyzed for the Hanoi tower-shaped fin distribution. The solid–liquid phase change frontier, melting time, temperature distribution, and streamline distribution were simulated and studied for different fin structures. Fins' combined effects on heat conduction and natural convection were examined. The Hanoi tower-shaped fins' structural parameters were optimized by applying response surface methodology (RSM). The results indicated that the Hanoi tower-shaped fin distribution considerably enhanced the phase change material's (PCM) melting rate and uniformity in the vertical circular tube heat accumulator. The significance levels of factors affecting the whole melting time were spacing tolerance (d) < length ratio (k) < bottommost spacing (P1). Within a certain range, the larger the bottommost spacing was, the synergistic heat transfer effect of natural convection and heat conduction was better. According to the RSM optimization results, when the length ratio was 1.2, the fin's bottommost spacing was 17.82 mm, and the spacing tolerance was 3.38 mm, the model had the shortest melting time. Compared with the uniform fin distribution, the total heat storage time was reduced by 18.04 %.

The Effect of Alloying Elements on Formation and Evolution Mechanism of Manganese‐Containing Inclusions in Medium/High‐Manganese Steels

The present work assesses the effect of alloying element of Mn, Al, C, and Si on formation and evolution behaviour of manganese‐containing inclusions in medium/high‐manganese steel. The results indicate that the manganese‐containing inclusions after Al addition were gradually transformed from MnO‐MnS into MnS, MnS‐Al2O3 and MnS‐Al2O3‐AlN‐TiN with large size of about 10 μm. Besides, as the Mn content increases, the main manganese‐containing inclusions are polyhedral MnS‐Al2O3 and MnS‐AlN with sharp edge, and the proportion of AlN and TiN in complex inclusions increases. Additionally, the increase of Mn content significantly reduces liquid phase temperature and extension of the solid‐liquid two phase zone, promoting the divorced eutectic transformation of type II to type III of MnS, lead to the polyhedral MnS preferentially precipitation at early stage of solidification process. Furthermore, it also observed that the main manganese‐containing inclusions were irregular MnS and MnS‐AlN with edge and larger sizes of 10–50μm in the case of manganese steel grades with high C or Si content, which is attributed to divorced eutectic transformation and increase of activity of S and Mn. Moreover, the C element possesses most obvious promoting effect on the precipitation of MnS, followed by Si and Mn elements.

Dual regulation of crystal structure and purity of Ti2SC in the Ti/TiC/FeS2 system via enhancing reactant contact and controlling crystal plane growth rates

Typically, the X-ray diffraction spectrum of a highly oriented structure (HOS) MAX phase displays a prominent (002) characteristic peak. Surprisingly, this principle does not hold true for Ti2SC. Instead, the synthesized Ti2SC consistently exhibits a polyhedral structure (PS). Furthermore, even with hot-pressing sintering, the purity of Ti2SC remains relatively low. The primary factors contributing to anomalous crystal structures and low purity are insufficient crystal growth and limited reactant contact. In this study, we successfully achieved dual regulation of the crystal structure and purity of Ti2SC within the Ti/TiC/FeS2 system, which was accomplished by enhancing reactant contact and controlling the growth rates of crystal planes. Notably, the intermediate products FeS and Fe, existing in a liquid phase at varying temperatures, played a crucial role in both the formation of Ti2SC and the growth of Ti2SC crystals. As a result, PS-Ti2SC and HOS–Ti2SC with purity greater than 99 wt% were successfully prepared. The formation of PS-Ti2SC can be attributed to the inadequate growth of each crystal plane at relatively lower temperatures (1500 °C). While the synthesis of HOS–Ti2SC necessitates the utilization of both a liquid phase and high temperature, as the epitaxial growth mechanism followed by vertical growth has been demonstrated to facilitate the generation of highly oriented crystals. The liquid phase facilitates the swift growth of Ti2SC crystals along the (001) crystal plane, while the (002) crystal plane necessitates a higher temperature (1760 °C) for relatively rapid growth. This work will open a new pathway for the development of the MAX phase from the perspective of crystal structure regulation and high purification preparation.

Simulation and optimization of square fin concentric tube heat storage exchanger

The square fin was used to improve the heat transfer rate of the concentric tube phase change heat exchanger. The effects of fin spacing, fin arrangement, and fin length on the melting process of phase change material (PCM) were studied. The influence and mechanism of non-uniform fin arrangement were discussed in detail. The liquid phase distribution and temperature distribution of PCM with time were analyzed. The results indicated that the heat exchanger with square fins can significantly improve the heat storage rate and shortened the complete melting time of PCM. Compared with heat exchangers without fins, the melting time of PCM in a 40 mm equidistant fin heat exchanger was shortened by 15.85%, and that in a 70 mm, non-uniformly spaced fin heat exchanger was shortened by 36.79%. Due to the different distances between the square fins and the outer boundary of the concentric tube, the temperature distribution near the square fin showed anisotropy, which enhanced the melting rate of PCM. The sensitivity order was fin arrangement &gt; fin length &gt; fin spacing. The research results can provide a reference for the design of phase change heat exchangers.

Co-Intercalation-Free Ether-Based Weakly Solvating Electrolytes Enable Fast-Charging and Wide-Temperature Lithium-Ion Batteries.

Ether-based electrolytes are competitive choices to meet the growing requirements for fast-charging and low-temperature lithium-ion batteries (LIBs) due to the low viscosity and low melting point of ether solvents. Unfortunately, the graphite (Gr) electrode is incompatible with commonly used ether solvents due to their irreversible co-intercalation into Gr interlayers. Here, we propose cyclopentyl methyl ether (CPME) as a co-intercalation-free ether solvent, which contains a cyclopentane group with large steric hindrance to obtain weakly solvating power with Li+ and a wide liquid-phase temperature range (-140 to +106 °C). A weakly solvating electrolyte (WSE) based on CPME and fluoroethylene carbonate (FEC) cosolvents can simultaneously achieve fast desolvation ability and high ionic conductivity, which also induces a LiF-rich solid electrolyte interphase (SEI) on the Gr anode. Therefore, the Gr/Li half-cell with this WSE can deliver outstanding rate capability, stable cycling performance, and high specific capacity (319 mAh g-1) at an ultralow temperature of -60 °C. Furthermore, a practical LiFePO4 (loading ≈25 mg cm-2)/Gr (loading ≈12 mg cm-2) pouch cell with this WSE also reveals outstanding rate capability and stable long-term cycling performance above 1000 cycles with a high Coulombic efficiency (≈99.9%) and achieves an impressive low-temperature application potential at -60 °C.