Titanium exhibits outstanding properties,particularly,high specific strength and resistance to both high and low temperatures,earning it a reputation as the metal of the future.However,because of the highly reactive n...Titanium exhibits outstanding properties,particularly,high specific strength and resistance to both high and low temperatures,earning it a reputation as the metal of the future.However,because of the highly reactive nature of titanium,metallic titanium production involves extensive procedures and high costs.Considering its advantages and limitations,the European Union has classified titanium metal as a critical raw material(CRM)of low category.The Kroll process is predominantly used to produce titanium;however,molten salt electrolysis(MSE)is currently being explored for producing metallic titanium at a low cost.Since 2000,electrolytic titanium production has undergone a wave of technological advancements.However,because of the intermediate and disproportionation reactions in the electrolytic titanium production process,the process efficiency and titanium purity according to industrial standards could not be achieved.Consequently,metallic titanium production has gradually diversified into employing technologies such as thermal reduction,MSE,and titanium alloy preparation.This study provides a comprehensive review of research advances in titanium metal preparation technologies over the past two decades,highlighting the challenges faced by the existing methods and proposing potential solutions.It offers useful insights into the development of low-cost titanium preparation technologies.展开更多
TiB_(2)coatings can significantly enhance the high-temperature oxidation resistance of molybdenum,which would broaden the application range of molybdenum and alloys thereof.However,traditional methods for preparing Ti...TiB_(2)coatings can significantly enhance the high-temperature oxidation resistance of molybdenum,which would broaden the application range of molybdenum and alloys thereof.However,traditional methods for preparing TiB_(2)coatings have disadvantages such as high equipment costs,complicated processes,and highly toxic gas emissions.This paper proposes an environmentally friendly method,which requires inexpensive equipment and simple processing,for preparing TiB_(2)coating on molybdenum via electrophoretic deposition within Na3AlF6-based molten salts.The produced TiB_(2)layer had an approximate thickness of 60μm and exhibited high density,outstanding hardness(38.2 GPa)and robust adhesion strength(51 N).Additionally,high-temperature oxidation experiments revealed that,at900℃,the TiB_(2)coating provided effective protection to the molybdenum substrate against oxidation for 3 h.This result indicates that the TiB_(2)coating prepared on molybdenum using molten salt electrophoretic deposition possesses good high-temperature oxidation resistance.展开更多
Based on the service characteristics of fuel elements for molten salt reactors,they need to have a high power density,resistance to coolant infiltration,and excellent thermodynamic properties.To solve the problem of t...Based on the service characteristics of fuel elements for molten salt reactors,they need to have a high power density,resistance to coolant infiltration,and excellent thermodynamic properties.To solve the problem of the graphite used in the fuel element for these reactors being susceptible to molten salt infiltration,carbon black(CB)was added to increase the density of the graphite,and a fuel element(TRISO(tri-structural isotropic)fuel particles were randomly distributed in the modified graphite matrix)was prepared by cold isostatic pressing process.An out-of-pile performance study shows that the densification and pore structure of the modified graphite matrix were improved,as was the resistance to molten salt infiltration.The median pore size of the modified graphite was reduced from 673 to 433 nm and the threshold pressure for molten salt(FLiBe,66%(molar fraction)LiF and 34%BeF_(2))infiltration was increased from 0.88 to 1.37 MPa.The isotropic CB made the graphite matrix less anisotropic,while its thermal conductivity and compressive strength were reduced due to the difficult graphitization of CB.Fuel elements containing 20%(volume fraction)TRISO particles were prepared.Numerical simulations show that the power and temperature distribution of the fuel were in line with the design requirements.The modified graphite matrix had a higher density,smaller pores,a lower anisotropy and a greater resistance to FLiBe infiltration.展开更多
Molten salt gasification is a promising technology for biomass conversion due to its advantages of superior heat transfer and the ability of utilizing solar energy to reduce carbon emission.In this study,the character...Molten salt gasification is a promising technology for biomass conversion due to its advantages of superior heat transfer and the ability of utilizing solar energy to reduce carbon emission.In this study,the characteristics of corncob CO_(2)-gasification in molten salt environments is thoroughly investigated,and the approach of introducing Fe_(2)O_(3) as catalyst to enhance the syngas yield is proposed.The results showed that the molten salts significantly promoted the conversion of corncob into gaseous products with very low tar and char yield.Compared to O_(2) and H_(2)O atmospheres,utilizing CO_(2) as gasifying agent enhanced the yield of gaseous products during the corncob gasification,especially the yields of CO and H_(2).The introduction of Fe_(2)O_(3) as a catalyst could further increase the yield of gaseous products and the cold gas efficiency(CGE),and the yield of syngas was increased into 2258.3 ml·g^(−1) with a high CGE of 105.8%in 900℃.The findings evidenced that CO_(2) gasification in the molten salt environment with Fe_(2)O_(3) addition can promote the cracking of tar,increasing the syngas yield significantly.Moreover,the energy required to drive the gasification process was calculated,and the total energy consumption was calculated as 16.83 GJ·t^(−1).The study opened up a new solution for the biomass gasification,exhibiting a great potential in distributed energy or chemical systems.展开更多
Present industrial decarbonization technologies require an active CO_(2)-concentration system,often based on lime reaction or amine binding reactions,which is energy intensive and carries a high CO_(2)-footprint.Here ...Present industrial decarbonization technologies require an active CO_(2)-concentration system,often based on lime reaction or amine binding reactions,which is energy intensive and carries a high CO_(2)-footprint.Here instead,an effective process without active CO_(2)concentration is demonstrated in a new process-termed IC2CNT(Insulationdiffusion facilitated CO_(2) to Carbon Nanomaterial Technology)decarbonization process.Molten carbonates such as Li_(2)CO_(3)(mp 723℃)are highly insoluble to industrial feed gas principal components(N2,O_(2),and H2O).However,CO_(2) can readily dissolve and react in molten carbonates.We have recently characterized high CO_(2) diffusion rates through porous aluminosilicate and calcium-magnesium silicate thermal insulations.Here,the CO_(2) in ambient feed gas passes through these membranes into molten Li_(2)CO_(3).The membrane also concurrently insulates the feed gas from the hot molten carbonate chamber,obviating the need to heat the(non-CO_(2))majority of the feed gas to high temperature.In this insulation facilitated decarbonization process CO_(2)is split by electrolysis in the molten carbonate producing sequestered,high-purity carbon nanomaterials(such as CNTs)and O_(2).展开更多
A static corrosion experiment of 347H stainless steel alloyed with elements Cu and Mo was carried out in a nitrate molten salt(60%NaNO_(3)+40%KNO_(3))at 565℃ for 720 h.The effects of elements Cu and Mo on the corrosi...A static corrosion experiment of 347H stainless steel alloyed with elements Cu and Mo was carried out in a nitrate molten salt(60%NaNO_(3)+40%KNO_(3))at 565℃ for 720 h.The effects of elements Cu and Mo on the corrosion resistance of 347H stainless steel in molten salt were investigated by analyzing the phase composition,microstructure and chemical composition of the corrosion products.The results show that the grain refinement induced by element Mo imparts the stainless steel with optimal corrosion resistance at a medium grain size.Furthermore,the formation of MoC significantly enhances the intergranular corrosion resistance of the stainless steel.The stainless steel exhibits uniform corrosion in the nitrate solution.The corrosion layer displays a dual-layer structure,and the corrosion products protecting matrix are present in both the inner and outer layers.The outer layer consists of a mixture of Fe oxides(Fe_(2)O_(3),Fe_(3)O_(4)),NaFeO_(2),and a minor amount of MgFe_(2)O_(4).Conversely,the inner layer is primarily composed of a spinel layer(FeCr_(2)O_(4),MgCr_(2)O_(4))and a thin Cu_(2)O layer.The oxidation of Cu in the inner layer leads to the formation of a dense Cu_(2)O layer,effectively impeding O_(2)-plasma infiltration into the matrix.展开更多
The reduction mechanism of Ir in the NaCl-KCl-IrCl3 molten salt was investigated by cyclic voltammetry and chronopotentiometry, and Ir film was deposited effectively on platinum in potentiostatic mode. The morphology ...The reduction mechanism of Ir in the NaCl-KCl-IrCl3 molten salt was investigated by cyclic voltammetry and chronopotentiometry, and Ir film was deposited effectively on platinum in potentiostatic mode. The morphology and constitution of Ir film were examined by scanning electron microscopy （SEM）, energy dispersive spectroscopy （EDS） and X-ray diffraction （XRD）. It is found that the reduction mechanism of Ir（III） is a three-electron step and electro reaction is a reversible diffusion controlled process; the diffusion coefficients of Ir（III） at 1083, 1113, 1143 and 1183 K are 1.56×10-4, 2.23×10-4, 2.77×10-4 and 4.40×10-4 cm2/s, respectively, while the activation energy of the electrode reaction is 102.95 kJ/mol. The compacted Ir film reveals that the applied potential greatly affects the deposition of Ir, the thickness of Ir film deposited at the potential of reduction peak is the highest, the temperature of the molten salt also exerts an influence on deposition, the film formed at a lower temperature is thinner, but more micropores would occur on film when the temperature went too high.展开更多
Herein, the electrochemical behaviors of Sr on inert W electrode and reactive Zn/Al electrodes were systematically investig-ated in LiCl–KCl–SrCl2molten salts at 773 K using various electrochemical methods. The chem...Herein, the electrochemical behaviors of Sr on inert W electrode and reactive Zn/Al electrodes were systematically investig-ated in LiCl–KCl–SrCl2molten salts at 773 K using various electrochemical methods. The chemical reaction potentials of Li and Sr on re-active Zn/Al electrodes were determined. We observed that Sr could be extracted by decreasing the activity of the deposited metal Sr onthe reactive electrode, although the standard reduction potential of Sr(II)/Sr was more negative than that of Li(I)/Li. The electrochemicalextraction products of Sr on reactive Zn and Al electrodes were Zn13Sr and Al4Sr, respectively, with no codeposition of Li observed.Based on the density functional theory calculations, both Zn13Sr and Al4Sr were identified as stable intermetallic compounds with Zn-/Al-rich phases. In LiCl–KCl molten salt containing 3wt% SrCl2, the coulombic efficiency of Sr in the Zn electrode was ~54%. The depolar-ization values for Sr on Zn and Al electrodes were 0.864 and 0.485 V, respectively, exhibiting a stronger chemical interaction between Znand Sr than between Al and Sr. This study suggests that using reactive electrodes can facilitate extraction of Sr accumulated while elec-trorefining molten salts, thereby enabling the purification and reuse of the salt and decreasing the volume of the nuclear waste.展开更多
This study investigates the anodic dissolution and electrochemical behavior of molybdenum in a NaCl-KCl molten salt system at 1023 K.The anodic dissolution process was systematically analyzed,revealing a sequential ox...This study investigates the anodic dissolution and electrochemical behavior of molybdenum in a NaCl-KCl molten salt system at 1023 K.The anodic dissolution process was systematically analyzed,revealing a sequential oxidation pathway of molybdenum into high-valence ions(Mo^(6+),Mo^(5+),Mo^(4+))under vary-ing electrolysis potentials.Electrochemical Impedance Spectroscopy(EIS)demonstrated that the dissolu-tion is governed by both charge transfer and diffusion mechanisms,with reduced impedance at higher potentials facilitating molybdenum dissolution.The reduction behavior of dissolved molybdenum ions was further explored using cyclic voltammetry(CV)and square wave voltammetry(SWV),confirming a multi-step reduction process controlled by diffusion and high reversibility.Nucleation studies using chronoamperometry established that molybdenum deposition follows an instantaneous nucleation mech-anism.Morphological analysis of cathodic deposits revealed that current density significantly influences particle size,transitioning from nano-sized spherical particles to larger equiaxed crystals with increasing current density.These findings provide a comprehensive understanding of molybdenum’s electrochemical properties in molten salts,offering valuable insights for optimizing electrolysis processes and advancing molybdenum-based material production.展开更多
Owing to the worldwide trend towards carbon neutrality,the number of Dy-containing heat-resistant Nd magnets used for wind power generation and electric vehicles is expected to increase exponentially.However,rare eart...Owing to the worldwide trend towards carbon neutrality,the number of Dy-containing heat-resistant Nd magnets used for wind power generation and electric vehicles is expected to increase exponentially.However,rare earth(RE)elements(especially Dy)are unevenly distributed globally.Therefore,an environmental-friendly recycling method for RE elements with a highly precise separation of Dy and Nd from end-of-life magnets is required to realize a carbon-neutral society.As an alternative to traditional hydrometallurgical RE separation techniques with a high environmental load,we designed a novel,highly efficient,and precise process for the separation and recycling of RE elements from magnet scrap.As a result,over 90%of the RE elements were efficiently extracted from the magnets using MgCl_(2)and evaporation loss was selectively suppressed by adding CaF_(2).The extracted RE elements were electrolytically separated based on the formation potential differences of the RE alloys.Nd and Dy metals with purities greater than 90%were estimated to be recovered at rates of 96%and 91%,respectively.Almost all the RE in the scraps could be separated and recycled as RE metals,and the byproducts were easily removed.Thus,this process is expected to be used on an industrial scale to realize a carbon-neutral society.展开更多
Molten salt reactors(MSRs)are a promising candidate for Generation IV reactor technologies,and the small modular molten salt reactor(SM-MSR),which utilizes low-enriched uranium and thorium fuels,is regarded as a wise ...Molten salt reactors(MSRs)are a promising candidate for Generation IV reactor technologies,and the small modular molten salt reactor(SM-MSR),which utilizes low-enriched uranium and thorium fuels,is regarded as a wise development path to accelerate deployment time.Uncertainty and sensitivity analyses of accidents guide nuclear reactor design and safety analyses.Uncertainty analysis can ascertain the safety margin,and sensitivity analysis can reveal the correlation between accident consequences and input parameters.Loss of forced cooling(LOFC)represents an accident scenario of the SM-MSR,and the study of LOFC could offer useful information to improve physical thermohydraulic and structural designs.Therefore,this study investigates the uncertainty of LOFC consequences and the sensitivity of related parameters.The uncertainty of the LOFC consequences was analyzed using the Monte Carlo method,and multiple linear regression was employed to analyze the sensitivity of the input parameters.The uncertainty and sensitivity analyses showed that the maximum reactor outlet fuel salt temperature was 725.5℃,which is lower than the acceptable criterion,and five important parameters influencing LOFC consequences were identified.展开更多
Large-sized titanium alloy ingots produced by vacuum arc remelting(VAR)technology are susceptible to metallurgical imperfections such as compositional segregation,inconsistent solidification microstructures,black spot...Large-sized titanium alloy ingots produced by vacuum arc remelting(VAR)technology are susceptible to metallurgical imperfections such as compositional segregation,inconsistent solidification microstructures,black spots,and inclusions.These defects are intricately linked to the electromagnetic effects,temperature distribution,and fluid dynamics during the melting process.The self-induced magnetic field created by the electric current,along with the axial magnetic field applied to stabilize the arc,significantly influences the solidification of titanium alloy ingots.A mathematical model optimized for the integrated analysis of multiple fields—electromagnetic,fluid,and thermal—was developed for the VAR solidification process of titanium alloys.The influence mechanism of electromagnetic field on the macroscopic solidification process of titanium alloy was investigated.The findings indicate the presence of two competing forces within the VAR molten pool,namely,thermal buoyancy and the Lorentz force.Introducing a coupled self-induced magnetic field and elevating the current to 15 kA led to an increase in the molten pool depth by 42.9%and a reduction in the thickness of the mushy zone by 25.2%.The application of a constant axial magnetic field enhances a unidirectional momentum buildup within the molten pool,thereby enhancing the flow velocity and cooling efficiency of melt.展开更多
Within the framework of carbon neutrality,lithium-ion batteries(LIBs)are progressively booming along with the growing utilization of green and clean energy.However,the extensive application of LIBs with limited lifesp...Within the framework of carbon neutrality,lithium-ion batteries(LIBs)are progressively booming along with the growing utilization of green and clean energy.However,the extensive application of LIBs with limited lifespan has brought about a significant recycling dilemma.The traditional hydrometallurgical or pyrometallurgical strategies are not capable to maximize the output value of spent LIBs and minimize the potential environmental hazards.Herein,to alternate the tedious and polluting treatment processes,we propose a high-temperature molten-salt strategy to directly regenerate spent cathodes of LIBs,which can also overcome the barrier of the incomplete defects'restoration with previous low-temperature molten salts.The high-energy and stable medium environment ensures a more thorough and efficient relithiation reaction,and simultaneously provides sufficient driving force for atomic rearrangement and grains secondary growth.In consequence,the regenerated ternary cathode(R-NCM)exhibits significantly enhanced structural stability that effectively suppresses the occurrence of cracks and harmful side reactions.The R-NCM delivers excellent cycling stability,retaining 81.2%of its capacity after 200 cycles at 1 C.This technique further optimizes the traditional eutectic molten-salt approach,broadening its applicability and improving regenerated cathode performance across a wider range of conditions.展开更多
The synergistic effects of irradiation and tensile deformation on the corrosion behavior of the GH3535 alloy in FLi-NaK molten salt were explored.Helium bubbles were introduced into the GH3535 alloy,followed by mechan...The synergistic effects of irradiation and tensile deformation on the corrosion behavior of the GH3535 alloy in FLi-NaK molten salt were explored.Helium bubbles were introduced into the GH3535 alloy,followed by mechanical loading with the plastic strain up to 10%.After immersion in molten salt for 300 h,all the samples exhibited a corrosion-induced Cr depletion layer.The depth of the Cr depletion layer increased by 40% for the alloy with helium ion irradiation and 10% plastic deformation,compared with that for the only corroded sample.Moreover,the proportion of large-sized helium bubbles increased with plastic deformation.These results indicate that the coupling effects of irradiation and tensile deformation accelerate the corrosion of the GH3535 alloy.In addition,in a molten salt environment,an unexpected outward migration behavior of helium bubbles was observed under different plastic deformation.Helium bubbles migrated closer to the surface as the strain increased up to 3%,while the migration depth declined when the strain reached 10%.This is ascribed to the interaction between deformation-induced dislocations and helium bubbles.展开更多
Carbon-based materials have been widely applied for pollutant removal relying on their rich pore structure,functional groups,chemical stability,and expandability.However,the traditional manufacturing process of carbon...Carbon-based materials have been widely applied for pollutant removal relying on their rich pore structure,functional groups,chemical stability,and expandability.However,the traditional manufacturing process of carbon materials based on organic compounds pyrolysis is high energy-consuming and high-emission,which is not conducive to addressing the climate crisis and achieving the goal of carbon neutrality.Molten salt electrolysis technology enables the direct capture and reduction of CO_(2)to produce solid carbon,resulting in significant environmental benefits while achieving carbon emissions reduction.The molten salt also has a purification function,enabling the production of high-purity carbon materials.The kinetics of the electrochemical reduction process can be easily controlled,and the co-reduction of multiple elements provides convenience for the in-situ optimization of carbon material structure and the expansion of its applications.Therefore,this review focuses on the thermodynamics&kinetics processes of molten salt capture and electrochemical reduction of CO_(2)to prepare carbon materials.It further reviews the recent research progress on the preparation of carbon materials for pollutant removal based on molten salt electrochemical processes for the first time.Finally,we analyze the advantages and challenges of the current molten salt electrochemical processes and offers prospects for future research directions.展开更多
Direct utilization of co-existed ferrous oxide(FeO)dust in CO_(2)flue gas from the steel industry to product value-added materials is yet to be established.Inspired by the form of CaO-CaCO_(3)as natural carbon cycle a...Direct utilization of co-existed ferrous oxide(FeO)dust in CO_(2)flue gas from the steel industry to product value-added materials is yet to be established.Inspired by the form of CaO-CaCO_(3)as natural carbon cycle and the high oxide dissolution capacity of molten salts,CaO is herein introduced into the affordable molten NaCl-CaCl_(2)-FeO salt to generate CO_(3)^(2-)through an efficient capture of CO_(2).The subsequent coelectrolysis of FeO and CO_(3)^(2-)successfully produces cathodic Fe-encapsulated carbon nanotubes(Fe@CNT)with enhanced energy efficiency(current efficiency of 83.1%for CO_(2)reduction and energy consumption of 22.49 kWh kg^(1)for Fe@CNT generation).The in-situ capture of CO_(2)by O^(2)generated from the electro-deoxidation of FeO bridges the electrolysis of CO_(2)and FeO,rendering the enhanced current efficiency of the co-electrolysis and template-free generation of Fe@CNT.When evaluated as functional materials for electromagnetic wave absorption,the Fe@CNT integrates dielectric loss of CNT and electromagnetic loss from Fe.The Fe well-defined in CNT induces the synergistic loss and further improves the impedance matching,resulting in excellent electromagnetic wave absorption performance.The coelectrolysis establishes a promising strategy for converting CO_(2)into highly functional materials directly from CO_(2)-containing flue gas from steel industrial without dust removal.展开更多
Single crystalline nickel rich Li[Ni_(x)Co_(y)Mn_(1-x–y)]O_(2)(SCNCM)layered oxide cathodes show higher ionic conductivity and better structure integrity than polycrystalline NCM(PCNCM)cathodes by eliminating grain b...Single crystalline nickel rich Li[Ni_(x)Co_(y)Mn_(1-x–y)]O_(2)(SCNCM)layered oxide cathodes show higher ionic conductivity and better structure integrity than polycrystalline NCM(PCNCM)cathodes by eliminating grain boundaries.However,it remains challenges in the controlled synthesis process and restricted cycling stability of SCNCM.Herein,take single crystalline nickel rich Li[Ni_(0.8)Co_(0.1)Mn_(0.1)]O_(2)(SC811)as an example,a dual molten salts(LiOH and Li_(2)SO_(4))assisted secondary calcination method is proposed,for which LiOH salt improves primary crystal size and Li_(2)SO_(4)prevents the aggravation of NCM nanocrystals.To further reduce the interfacial side reactions,Mg-doping and B-coating surface modification was carried out,which effectively suppress anisotropic lattice changes and Li/Ni disorder.In addition,a thin and uniform H_(3)BO_(3)coating effectively prevents direct contact between the electrode and electrolyte,thus reducing harmful parasitic reactions.The single crystal structure engineering and surface modification strategy of oxide layered cathodes significantly improve the cycling stability of the modified SC811 cathode.For example,during a long-term cycling of 470 cycles,a high-capacity retention of 74.2%obtained at 1C rate.Our work provides a new strategy for engineering high energy nickel rich layered oxide NCM cathodes.展开更多
A new flow control technology in continuous casting process named permanent magnet flow control-mold(PMFC-Mold)was proposed,in which the permanent magnets are arranged in Halbach array near the narrow region of the mo...A new flow control technology in continuous casting process named permanent magnet flow control-mold(PMFC-Mold)was proposed,in which the permanent magnets are arranged in Halbach array near the narrow region of the mold.The behavior of molten steel flow and the fluctuation of molten steel/slag interface in the PMFC-Mold under different continuous casting speeds were investigated.Firstly,a physical experiment of liquid Ga-In-Sn alloy circulating flow was carried out in Perspex mold with Halbach’s permanent magnets(HPMs)to investigate the magnetic field distribution of HPMs and its impactful electromagnetic braking effect.The numerical simulation of 1450 mm×230 mm slab shows that a stronger magnetic field over 0.3-0.625 T is formed at the wide surface and the narrow surface of the mold,which provides an effective electromagnetic braking for controlling the impingement of molten steel jet and suppressing the fluctuation of molten steel/slag interface.The numerical simulation results show that in the PMFC-Mold,the region with the turbulent kinetic energy greater than 0.01 and 0.04 m^(2)s^(-2)on the upper backflow zone and near the narrow surface of the mold are significantly reduced.The maximum turbulent kinetic energy of the submerged entry nozzle(SEN)jet in front of the narrow surface is significantly reduced,and the SEN jet moves downward before impacting the narrow surface of the mold.In the PMFC-Mold,the region with the surface velocity greater than 0.2 m s^(-1)on the steel/slag interface is eliminated,the flow pattern and fluctuation profiles on the molten steel/slag interface become regular on both sides of SEN,and the vortex near SEN disappears.The maximum fluctuation height of molten steel/slag interface is controlled below 2.59 and 5.40 mm corresponding to the casting speed of 1.6 and 2.0 m min-1,respectively.展开更多
The thermocline energy storage tank(TEST)serves as a crucial component in thermal energy storage systems,utilizing the working fluid that enters through a diffuser to store and harness energy.However,the conventional ...The thermocline energy storage tank(TEST)serves as a crucial component in thermal energy storage systems,utilizing the working fluid that enters through a diffuser to store and harness energy.However,the conventional double-plate radial diffuser is ill-suited for a single-medium TEST’s full tank storage due to its unidirectional fluid inflow.There has been a notable lack of optimization analysis of diffusers.Two innovative tubular diffuser designs with reduced cross-sectional areas have been introduced:the annular-arranged diffuser(AAD)and the cross-arranged diffuser(CAD).To elucidate the impact of diffuser designs on energy storage efficiency,a 3D transient computational fluid dynamics(CFD)model was established to simulate a thermocline formation under two diffuser types.The model was validated against experimental data.Results showed that the thermocline of AAD was 11.39%thinner than that of a traditional double-plate diffuser.In the process of charging and discharging,the time-varying thermocline and factors influencing thermocline thickness were analyzed.Results indicate that in the mixed dominant region,increased turbulent kinetic energy correlates with reduced thermocline thickness.Notably,the AAD’s stable thermocline was 4.23%and 5.41%thinner than the CAD’s during charging and discharging,respectively,making the AAD preferable for engineering applications.The effects of tube diameter and orifice opening angle on temperature stratification performance were also examined.The findings suggest that an inclined impact jet and large-diameter tubes are more conducive to temperature stratification.Moreover,an orifice diameter optimization method was developed,which can decrease the thermocline by 6.78%.展开更多
In photothermal power(solar energy)generation systems,purging residual molten salt from pipelines using highpressure gas poses a significant challenge,particularly in clearing the bottom of regulating valves.Ineffecti...In photothermal power(solar energy)generation systems,purging residual molten salt from pipelines using highpressure gas poses a significant challenge,particularly in clearing the bottom of regulating valves.Ineffective purging can lead to crystallization of the molten salt,resulting in blockages.To address this issue,understanding the gas-liquid two-phase flow dynamics during high-pressure gas purging is crucial.This study utilizes the Volume of Fluid(VOF)model and adaptive dynamic grids to simulate the gas-liquid two-phase flow during the purging process in a DN50 PN50 conventional molten salt regulating valve.Initially,the reliability of the CFD simulations is validated through comparisons with experimental data and findings from the literature.Subsequently,simulation experiments are conducted to analyze the effects of various factors,including purge flow rates,initial liquid accumulation masses,purge durations,and the profiles of the valve bottom flow channels.The results indicate that the purging process comprises four distinct stages:Initial violent surge stage,liquid discharge stage,liquid partial fallback stage,liquid dissipation stage.For an initial liquid height of 17 mm at the bottom of the valve,the critical purge flow rate lies between 3 and 5 m/s.Notably,the critical purge flow rate is independent of the initial liquid accumulation mass.As the purge gas flow rate increases,the volume of liquid discharged also increases.Beyond the critical purge flow rate,higher purge gas velocities lead to shorter purge durations.Interestingly,the residual liquid mass after purging remains unaffected by the initial liquid accumulation.Additionally,the flow channel profile at the bottom of the valve significantly influences both the critical purge speed and the efficiency of the purging process.展开更多
基金financial support from the Yunnan Province Key Industries Science and Technology Special Project for Colleges and UniversitiesChina(No.FWCY-QYCT2024006)+6 种基金National Natural Science Foundation of China(Nos.52104351 and 52364051)Science and Technology Major Project of Yunnan Province,China(No.202202AG050007)the Yunnan Fundamental Research ProjectsChina(No.202401AT070314)the Key Technology Research and Development Program of Shandong Province,China(No.2023CXGC010903)Central Guidance Local Scientific and Technological Development Funds,China(No.202407AB110022)Yunnan Province Xingdian Talent Support Plan Project,China。
文摘Titanium exhibits outstanding properties,particularly,high specific strength and resistance to both high and low temperatures,earning it a reputation as the metal of the future.However,because of the highly reactive nature of titanium,metallic titanium production involves extensive procedures and high costs.Considering its advantages and limitations,the European Union has classified titanium metal as a critical raw material(CRM)of low category.The Kroll process is predominantly used to produce titanium;however,molten salt electrolysis(MSE)is currently being explored for producing metallic titanium at a low cost.Since 2000,electrolytic titanium production has undergone a wave of technological advancements.However,because of the intermediate and disproportionation reactions in the electrolytic titanium production process,the process efficiency and titanium purity according to industrial standards could not be achieved.Consequently,metallic titanium production has gradually diversified into employing technologies such as thermal reduction,MSE,and titanium alloy preparation.This study provides a comprehensive review of research advances in titanium metal preparation technologies over the past two decades,highlighting the challenges faced by the existing methods and proposing potential solutions.It offers useful insights into the development of low-cost titanium preparation technologies.
基金supported by the Original Exploratory Program of the National Natural Science Foundation of China(No.52450012)。
文摘TiB_(2)coatings can significantly enhance the high-temperature oxidation resistance of molybdenum,which would broaden the application range of molybdenum and alloys thereof.However,traditional methods for preparing TiB_(2)coatings have disadvantages such as high equipment costs,complicated processes,and highly toxic gas emissions.This paper proposes an environmentally friendly method,which requires inexpensive equipment and simple processing,for preparing TiB_(2)coating on molybdenum via electrophoretic deposition within Na3AlF6-based molten salts.The produced TiB_(2)layer had an approximate thickness of 60μm and exhibited high density,outstanding hardness(38.2 GPa)and robust adhesion strength(51 N).Additionally,high-temperature oxidation experiments revealed that,at900℃,the TiB_(2)coating provided effective protection to the molybdenum substrate against oxidation for 3 h.This result indicates that the TiB_(2)coating prepared on molybdenum using molten salt electrophoretic deposition possesses good high-temperature oxidation resistance.
文摘Based on the service characteristics of fuel elements for molten salt reactors,they need to have a high power density,resistance to coolant infiltration,and excellent thermodynamic properties.To solve the problem of the graphite used in the fuel element for these reactors being susceptible to molten salt infiltration,carbon black(CB)was added to increase the density of the graphite,and a fuel element(TRISO(tri-structural isotropic)fuel particles were randomly distributed in the modified graphite matrix)was prepared by cold isostatic pressing process.An out-of-pile performance study shows that the densification and pore structure of the modified graphite matrix were improved,as was the resistance to molten salt infiltration.The median pore size of the modified graphite was reduced from 673 to 433 nm and the threshold pressure for molten salt(FLiBe,66%(molar fraction)LiF and 34%BeF_(2))infiltration was increased from 0.88 to 1.37 MPa.The isotropic CB made the graphite matrix less anisotropic,while its thermal conductivity and compressive strength were reduced due to the difficult graphitization of CB.Fuel elements containing 20%(volume fraction)TRISO particles were prepared.Numerical simulations show that the power and temperature distribution of the fuel were in line with the design requirements.The modified graphite matrix had a higher density,smaller pores,a lower anisotropy and a greater resistance to FLiBe infiltration.
基金supported by the National Natural Science Foundation of China(52066007,22279048)the Major Science and Technology Project of Yunnan Province(202202AG050017).
文摘Molten salt gasification is a promising technology for biomass conversion due to its advantages of superior heat transfer and the ability of utilizing solar energy to reduce carbon emission.In this study,the characteristics of corncob CO_(2)-gasification in molten salt environments is thoroughly investigated,and the approach of introducing Fe_(2)O_(3) as catalyst to enhance the syngas yield is proposed.The results showed that the molten salts significantly promoted the conversion of corncob into gaseous products with very low tar and char yield.Compared to O_(2) and H_(2)O atmospheres,utilizing CO_(2) as gasifying agent enhanced the yield of gaseous products during the corncob gasification,especially the yields of CO and H_(2).The introduction of Fe_(2)O_(3) as a catalyst could further increase the yield of gaseous products and the cold gas efficiency(CGE),and the yield of syngas was increased into 2258.3 ml·g^(−1) with a high CGE of 105.8%in 900℃.The findings evidenced that CO_(2) gasification in the molten salt environment with Fe_(2)O_(3) addition can promote the cracking of tar,increasing the syngas yield significantly.Moreover,the energy required to drive the gasification process was calculated,and the total energy consumption was calculated as 16.83 GJ·t^(−1).The study opened up a new solution for the biomass gasification,exhibiting a great potential in distributed energy or chemical systems.
文摘Present industrial decarbonization technologies require an active CO_(2)-concentration system,often based on lime reaction or amine binding reactions,which is energy intensive and carries a high CO_(2)-footprint.Here instead,an effective process without active CO_(2)concentration is demonstrated in a new process-termed IC2CNT(Insulationdiffusion facilitated CO_(2) to Carbon Nanomaterial Technology)decarbonization process.Molten carbonates such as Li_(2)CO_(3)(mp 723℃)are highly insoluble to industrial feed gas principal components(N2,O_(2),and H2O).However,CO_(2) can readily dissolve and react in molten carbonates.We have recently characterized high CO_(2) diffusion rates through porous aluminosilicate and calcium-magnesium silicate thermal insulations.Here,the CO_(2) in ambient feed gas passes through these membranes into molten Li_(2)CO_(3).The membrane also concurrently insulates the feed gas from the hot molten carbonate chamber,obviating the need to heat the(non-CO_(2))majority of the feed gas to high temperature.In this insulation facilitated decarbonization process CO_(2)is split by electrolysis in the molten carbonate producing sequestered,high-purity carbon nanomaterials(such as CNTs)and O_(2).
基金Science and Technology Program Project of Gansu Province(21ZD3GB001)。
文摘A static corrosion experiment of 347H stainless steel alloyed with elements Cu and Mo was carried out in a nitrate molten salt(60%NaNO_(3)+40%KNO_(3))at 565℃ for 720 h.The effects of elements Cu and Mo on the corrosion resistance of 347H stainless steel in molten salt were investigated by analyzing the phase composition,microstructure and chemical composition of the corrosion products.The results show that the grain refinement induced by element Mo imparts the stainless steel with optimal corrosion resistance at a medium grain size.Furthermore,the formation of MoC significantly enhances the intergranular corrosion resistance of the stainless steel.The stainless steel exhibits uniform corrosion in the nitrate solution.The corrosion layer displays a dual-layer structure,and the corrosion products protecting matrix are present in both the inner and outer layers.The outer layer consists of a mixture of Fe oxides(Fe_(2)O_(3),Fe_(3)O_(4)),NaFeO_(2),and a minor amount of MgFe_(2)O_(4).Conversely,the inner layer is primarily composed of a spinel layer(FeCr_(2)O_(4),MgCr_(2)O_(4))and a thin Cu_(2)O layer.The oxidation of Cu in the inner layer leads to the formation of a dense Cu_(2)O layer,effectively impeding O_(2)-plasma infiltration into the matrix.
文摘The reduction mechanism of Ir in the NaCl-KCl-IrCl3 molten salt was investigated by cyclic voltammetry and chronopotentiometry, and Ir film was deposited effectively on platinum in potentiostatic mode. The morphology and constitution of Ir film were examined by scanning electron microscopy （SEM）, energy dispersive spectroscopy （EDS） and X-ray diffraction （XRD）. It is found that the reduction mechanism of Ir（III） is a three-electron step and electro reaction is a reversible diffusion controlled process; the diffusion coefficients of Ir（III） at 1083, 1113, 1143 and 1183 K are 1.56×10-4, 2.23×10-4, 2.77×10-4 and 4.40×10-4 cm2/s, respectively, while the activation energy of the electrode reaction is 102.95 kJ/mol. The compacted Ir film reveals that the applied potential greatly affects the deposition of Ir, the thickness of Ir film deposited at the potential of reduction peak is the highest, the temperature of the molten salt also exerts an influence on deposition, the film formed at a lower temperature is thinner, but more micropores would occur on film when the temperature went too high.
基金financially supported by the National Postdoctoral Program for Innovative Talents, China (No. BX2021327)the National Natural Science Foundation of China (Nos. 22206194 and U2267222)+1 种基金the Ningbo Natural Science Foundation of China (No. 2023J337)the Yongjiang Talent Introduction Programme, China (No. 2 021A-161-G)。
文摘Herein, the electrochemical behaviors of Sr on inert W electrode and reactive Zn/Al electrodes were systematically investig-ated in LiCl–KCl–SrCl2molten salts at 773 K using various electrochemical methods. The chemical reaction potentials of Li and Sr on re-active Zn/Al electrodes were determined. We observed that Sr could be extracted by decreasing the activity of the deposited metal Sr onthe reactive electrode, although the standard reduction potential of Sr(II)/Sr was more negative than that of Li(I)/Li. The electrochemicalextraction products of Sr on reactive Zn and Al electrodes were Zn13Sr and Al4Sr, respectively, with no codeposition of Li observed.Based on the density functional theory calculations, both Zn13Sr and Al4Sr were identified as stable intermetallic compounds with Zn-/Al-rich phases. In LiCl–KCl molten salt containing 3wt% SrCl2, the coulombic efficiency of Sr in the Zn electrode was ~54%. The depolar-ization values for Sr on Zn and Al electrodes were 0.864 and 0.485 V, respectively, exhibiting a stronger chemical interaction between Znand Sr than between Al and Sr. This study suggests that using reactive electrodes can facilitate extraction of Sr accumulated while elec-trorefining molten salts, thereby enabling the purification and reuse of the salt and decreasing the volume of the nuclear waste.
基金financially supported by the National Natural Science Foundation of China for Distinguished Young Scholar(No.52025042)the Open Fund of State Key Laboratory of Advanced Metallurgy(No.KF24-12)。
文摘This study investigates the anodic dissolution and electrochemical behavior of molybdenum in a NaCl-KCl molten salt system at 1023 K.The anodic dissolution process was systematically analyzed,revealing a sequential oxidation pathway of molybdenum into high-valence ions(Mo^(6+),Mo^(5+),Mo^(4+))under vary-ing electrolysis potentials.Electrochemical Impedance Spectroscopy(EIS)demonstrated that the dissolu-tion is governed by both charge transfer and diffusion mechanisms,with reduced impedance at higher potentials facilitating molybdenum dissolution.The reduction behavior of dissolved molybdenum ions was further explored using cyclic voltammetry(CV)and square wave voltammetry(SWV),confirming a multi-step reduction process controlled by diffusion and high reversibility.Nucleation studies using chronoamperometry established that molybdenum deposition follows an instantaneous nucleation mech-anism.Morphological analysis of cathodic deposits revealed that current density significantly influences particle size,transitioning from nano-sized spherical particles to larger equiaxed crystals with increasing current density.These findings provide a comprehensive understanding of molybdenum’s electrochemical properties in molten salts,offering valuable insights for optimizing electrolysis processes and advancing molybdenum-based material production.
基金supported by a Grant-in-Aid from the Japan Society for the Promotion of Science(JSPS)Fellows(19J20301).
文摘Owing to the worldwide trend towards carbon neutrality,the number of Dy-containing heat-resistant Nd magnets used for wind power generation and electric vehicles is expected to increase exponentially.However,rare earth(RE)elements(especially Dy)are unevenly distributed globally.Therefore,an environmental-friendly recycling method for RE elements with a highly precise separation of Dy and Nd from end-of-life magnets is required to realize a carbon-neutral society.As an alternative to traditional hydrometallurgical RE separation techniques with a high environmental load,we designed a novel,highly efficient,and precise process for the separation and recycling of RE elements from magnet scrap.As a result,over 90%of the RE elements were efficiently extracted from the magnets using MgCl_(2)and evaporation loss was selectively suppressed by adding CaF_(2).The extracted RE elements were electrolytically separated based on the formation potential differences of the RE alloys.Nd and Dy metals with purities greater than 90%were estimated to be recovered at rates of 96%and 91%,respectively.Almost all the RE in the scraps could be separated and recycled as RE metals,and the byproducts were easily removed.Thus,this process is expected to be used on an industrial scale to realize a carbon-neutral society.
基金supported by the Youth Innovation Promotion Association(YIPA)(No.E329290101)of the Chinese Academy of Sciences。
文摘Molten salt reactors(MSRs)are a promising candidate for Generation IV reactor technologies,and the small modular molten salt reactor(SM-MSR),which utilizes low-enriched uranium and thorium fuels,is regarded as a wise development path to accelerate deployment time.Uncertainty and sensitivity analyses of accidents guide nuclear reactor design and safety analyses.Uncertainty analysis can ascertain the safety margin,and sensitivity analysis can reveal the correlation between accident consequences and input parameters.Loss of forced cooling(LOFC)represents an accident scenario of the SM-MSR,and the study of LOFC could offer useful information to improve physical thermohydraulic and structural designs.Therefore,this study investigates the uncertainty of LOFC consequences and the sensitivity of related parameters.The uncertainty of the LOFC consequences was analyzed using the Monte Carlo method,and multiple linear regression was employed to analyze the sensitivity of the input parameters.The uncertainty and sensitivity analyses showed that the maximum reactor outlet fuel salt temperature was 725.5℃,which is lower than the acceptable criterion,and five important parameters influencing LOFC consequences were identified.
基金financially supported by the National Natural Science Foundation of China(Nos.52422408 and 52171031)the Excellent Youth Fund of Liaoning Natural Science Foundation(No.2023JH3/10200001)the Liaoning Xingliao Talents-Top-notch Young Talents Project(No.XLYC2203064).
文摘Large-sized titanium alloy ingots produced by vacuum arc remelting(VAR)technology are susceptible to metallurgical imperfections such as compositional segregation,inconsistent solidification microstructures,black spots,and inclusions.These defects are intricately linked to the electromagnetic effects,temperature distribution,and fluid dynamics during the melting process.The self-induced magnetic field created by the electric current,along with the axial magnetic field applied to stabilize the arc,significantly influences the solidification of titanium alloy ingots.A mathematical model optimized for the integrated analysis of multiple fields—electromagnetic,fluid,and thermal—was developed for the VAR solidification process of titanium alloys.The influence mechanism of electromagnetic field on the macroscopic solidification process of titanium alloy was investigated.The findings indicate the presence of two competing forces within the VAR molten pool,namely,thermal buoyancy and the Lorentz force.Introducing a coupled self-induced magnetic field and elevating the current to 15 kA led to an increase in the molten pool depth by 42.9%and a reduction in the thickness of the mushy zone by 25.2%.The application of a constant axial magnetic field enhances a unidirectional momentum buildup within the molten pool,thereby enhancing the flow velocity and cooling efficiency of melt.
基金support by National Natural Science Foundation of China(22379166)Natural Science Foundation for Distinguished Young Scholars of Hunan Province(2022JJ10089)Central South University Innovation-Driven Research Programme(2023CXQD034).
文摘Within the framework of carbon neutrality,lithium-ion batteries(LIBs)are progressively booming along with the growing utilization of green and clean energy.However,the extensive application of LIBs with limited lifespan has brought about a significant recycling dilemma.The traditional hydrometallurgical or pyrometallurgical strategies are not capable to maximize the output value of spent LIBs and minimize the potential environmental hazards.Herein,to alternate the tedious and polluting treatment processes,we propose a high-temperature molten-salt strategy to directly regenerate spent cathodes of LIBs,which can also overcome the barrier of the incomplete defects'restoration with previous low-temperature molten salts.The high-energy and stable medium environment ensures a more thorough and efficient relithiation reaction,and simultaneously provides sufficient driving force for atomic rearrangement and grains secondary growth.In consequence,the regenerated ternary cathode(R-NCM)exhibits significantly enhanced structural stability that effectively suppresses the occurrence of cracks and harmful side reactions.The R-NCM delivers excellent cycling stability,retaining 81.2%of its capacity after 200 cycles at 1 C.This technique further optimizes the traditional eutectic molten-salt approach,broadening its applicability and improving regenerated cathode performance across a wider range of conditions.
基金supported by the National Natural Science Foundation of China(Nos.12425511,12375280,U2341261,U23B2072 and 12305293).
文摘The synergistic effects of irradiation and tensile deformation on the corrosion behavior of the GH3535 alloy in FLi-NaK molten salt were explored.Helium bubbles were introduced into the GH3535 alloy,followed by mechanical loading with the plastic strain up to 10%.After immersion in molten salt for 300 h,all the samples exhibited a corrosion-induced Cr depletion layer.The depth of the Cr depletion layer increased by 40% for the alloy with helium ion irradiation and 10% plastic deformation,compared with that for the only corroded sample.Moreover,the proportion of large-sized helium bubbles increased with plastic deformation.These results indicate that the coupling effects of irradiation and tensile deformation accelerate the corrosion of the GH3535 alloy.In addition,in a molten salt environment,an unexpected outward migration behavior of helium bubbles was observed under different plastic deformation.Helium bubbles migrated closer to the surface as the strain increased up to 3%,while the migration depth declined when the strain reached 10%.This is ascribed to the interaction between deformation-induced dislocations and helium bubbles.
基金supported by the National Natural Science Foundation of China(Nos.52200143,51979011 and 52276208)the Natural Science Foundation of Hubei Province(No.2024AFB546)the Fundamental Research Funds for Central Public Welfare Research Institutes(Nos.CKSF2023302/CL and CKSF2023314/CL).
文摘Carbon-based materials have been widely applied for pollutant removal relying on their rich pore structure,functional groups,chemical stability,and expandability.However,the traditional manufacturing process of carbon materials based on organic compounds pyrolysis is high energy-consuming and high-emission,which is not conducive to addressing the climate crisis and achieving the goal of carbon neutrality.Molten salt electrolysis technology enables the direct capture and reduction of CO_(2)to produce solid carbon,resulting in significant environmental benefits while achieving carbon emissions reduction.The molten salt also has a purification function,enabling the production of high-purity carbon materials.The kinetics of the electrochemical reduction process can be easily controlled,and the co-reduction of multiple elements provides convenience for the in-situ optimization of carbon material structure and the expansion of its applications.Therefore,this review focuses on the thermodynamics&kinetics processes of molten salt capture and electrochemical reduction of CO_(2)to prepare carbon materials.It further reviews the recent research progress on the preparation of carbon materials for pollutant removal based on molten salt electrochemical processes for the first time.Finally,we analyze the advantages and challenges of the current molten salt electrochemical processes and offers prospects for future research directions.
基金supported by the National Key R&D Program of China(2023YFA1508001)the National Natural Science Foundation of China(22272120 and U2202251)+2 种基金the Fundamental Research Funds for the Central Universities(2042022kf1174)the Hainan Province Science and Technology Special Fund(ZDYF2023SHFZ120 and ZDYF2021SHFZ058)the Research Foundation of Marine Science and Technology Collaborative Innovation Center of Hainan University(XTCX2022HYB01)。
文摘Direct utilization of co-existed ferrous oxide(FeO)dust in CO_(2)flue gas from the steel industry to product value-added materials is yet to be established.Inspired by the form of CaO-CaCO_(3)as natural carbon cycle and the high oxide dissolution capacity of molten salts,CaO is herein introduced into the affordable molten NaCl-CaCl_(2)-FeO salt to generate CO_(3)^(2-)through an efficient capture of CO_(2).The subsequent coelectrolysis of FeO and CO_(3)^(2-)successfully produces cathodic Fe-encapsulated carbon nanotubes(Fe@CNT)with enhanced energy efficiency(current efficiency of 83.1%for CO_(2)reduction and energy consumption of 22.49 kWh kg^(1)for Fe@CNT generation).The in-situ capture of CO_(2)by O^(2)generated from the electro-deoxidation of FeO bridges the electrolysis of CO_(2)and FeO,rendering the enhanced current efficiency of the co-electrolysis and template-free generation of Fe@CNT.When evaluated as functional materials for electromagnetic wave absorption,the Fe@CNT integrates dielectric loss of CNT and electromagnetic loss from Fe.The Fe well-defined in CNT induces the synergistic loss and further improves the impedance matching,resulting in excellent electromagnetic wave absorption performance.The coelectrolysis establishes a promising strategy for converting CO_(2)into highly functional materials directly from CO_(2)-containing flue gas from steel industrial without dust removal.
基金financially supported by the National Natural Science Foundation of China under the Grant No.22209075。
文摘Single crystalline nickel rich Li[Ni_(x)Co_(y)Mn_(1-x–y)]O_(2)(SCNCM)layered oxide cathodes show higher ionic conductivity and better structure integrity than polycrystalline NCM(PCNCM)cathodes by eliminating grain boundaries.However,it remains challenges in the controlled synthesis process and restricted cycling stability of SCNCM.Herein,take single crystalline nickel rich Li[Ni_(0.8)Co_(0.1)Mn_(0.1)]O_(2)(SC811)as an example,a dual molten salts(LiOH and Li_(2)SO_(4))assisted secondary calcination method is proposed,for which LiOH salt improves primary crystal size and Li_(2)SO_(4)prevents the aggravation of NCM nanocrystals.To further reduce the interfacial side reactions,Mg-doping and B-coating surface modification was carried out,which effectively suppress anisotropic lattice changes and Li/Ni disorder.In addition,a thin and uniform H_(3)BO_(3)coating effectively prevents direct contact between the electrode and electrolyte,thus reducing harmful parasitic reactions.The single crystal structure engineering and surface modification strategy of oxide layered cathodes significantly improve the cycling stability of the modified SC811 cathode.For example,during a long-term cycling of 470 cycles,a high-capacity retention of 74.2%obtained at 1C rate.Our work provides a new strategy for engineering high energy nickel rich layered oxide NCM cathodes.
基金the National Natural Science Foundation of China(Grant No.U1760206 and Grant No.51574083)the 111 Project(2.0)of China(No.BP0719037)for the financial support.
文摘A new flow control technology in continuous casting process named permanent magnet flow control-mold(PMFC-Mold)was proposed,in which the permanent magnets are arranged in Halbach array near the narrow region of the mold.The behavior of molten steel flow and the fluctuation of molten steel/slag interface in the PMFC-Mold under different continuous casting speeds were investigated.Firstly,a physical experiment of liquid Ga-In-Sn alloy circulating flow was carried out in Perspex mold with Halbach’s permanent magnets(HPMs)to investigate the magnetic field distribution of HPMs and its impactful electromagnetic braking effect.The numerical simulation of 1450 mm×230 mm slab shows that a stronger magnetic field over 0.3-0.625 T is formed at the wide surface and the narrow surface of the mold,which provides an effective electromagnetic braking for controlling the impingement of molten steel jet and suppressing the fluctuation of molten steel/slag interface.The numerical simulation results show that in the PMFC-Mold,the region with the turbulent kinetic energy greater than 0.01 and 0.04 m^(2)s^(-2)on the upper backflow zone and near the narrow surface of the mold are significantly reduced.The maximum turbulent kinetic energy of the submerged entry nozzle(SEN)jet in front of the narrow surface is significantly reduced,and the SEN jet moves downward before impacting the narrow surface of the mold.In the PMFC-Mold,the region with the surface velocity greater than 0.2 m s^(-1)on the steel/slag interface is eliminated,the flow pattern and fluctuation profiles on the molten steel/slag interface become regular on both sides of SEN,and the vortex near SEN disappears.The maximum fluctuation height of molten steel/slag interface is controlled below 2.59 and 5.40 mm corresponding to the casting speed of 1.6 and 2.0 m min-1,respectively.
基金supported by the National Natural Science Foundation of China(No.52375274)the Zhejiang Provincial Natural Science Foundation of China(No.LD21E050003)+1 种基金the Key R&D Program of Zhejiang Province(No.2023C01229)the Central Government Fund for Regional Science and Technology Development of China(No.2023ZY1033).
文摘The thermocline energy storage tank(TEST)serves as a crucial component in thermal energy storage systems,utilizing the working fluid that enters through a diffuser to store and harness energy.However,the conventional double-plate radial diffuser is ill-suited for a single-medium TEST’s full tank storage due to its unidirectional fluid inflow.There has been a notable lack of optimization analysis of diffusers.Two innovative tubular diffuser designs with reduced cross-sectional areas have been introduced:the annular-arranged diffuser(AAD)and the cross-arranged diffuser(CAD).To elucidate the impact of diffuser designs on energy storage efficiency,a 3D transient computational fluid dynamics(CFD)model was established to simulate a thermocline formation under two diffuser types.The model was validated against experimental data.Results showed that the thermocline of AAD was 11.39%thinner than that of a traditional double-plate diffuser.In the process of charging and discharging,the time-varying thermocline and factors influencing thermocline thickness were analyzed.Results indicate that in the mixed dominant region,increased turbulent kinetic energy correlates with reduced thermocline thickness.Notably,the AAD’s stable thermocline was 4.23%and 5.41%thinner than the CAD’s during charging and discharging,respectively,making the AAD preferable for engineering applications.The effects of tube diameter and orifice opening angle on temperature stratification performance were also examined.The findings suggest that an inclined impact jet and large-diameter tubes are more conducive to temperature stratification.Moreover,an orifice diameter optimization method was developed,which can decrease the thermocline by 6.78%.
文摘In photothermal power(solar energy)generation systems,purging residual molten salt from pipelines using highpressure gas poses a significant challenge,particularly in clearing the bottom of regulating valves.Ineffective purging can lead to crystallization of the molten salt,resulting in blockages.To address this issue,understanding the gas-liquid two-phase flow dynamics during high-pressure gas purging is crucial.This study utilizes the Volume of Fluid(VOF)model and adaptive dynamic grids to simulate the gas-liquid two-phase flow during the purging process in a DN50 PN50 conventional molten salt regulating valve.Initially,the reliability of the CFD simulations is validated through comparisons with experimental data and findings from the literature.Subsequently,simulation experiments are conducted to analyze the effects of various factors,including purge flow rates,initial liquid accumulation masses,purge durations,and the profiles of the valve bottom flow channels.The results indicate that the purging process comprises four distinct stages:Initial violent surge stage,liquid discharge stage,liquid partial fallback stage,liquid dissipation stage.For an initial liquid height of 17 mm at the bottom of the valve,the critical purge flow rate lies between 3 and 5 m/s.Notably,the critical purge flow rate is independent of the initial liquid accumulation mass.As the purge gas flow rate increases,the volume of liquid discharged also increases.Beyond the critical purge flow rate,higher purge gas velocities lead to shorter purge durations.Interestingly,the residual liquid mass after purging remains unaffected by the initial liquid accumulation.Additionally,the flow channel profile at the bottom of the valve significantly influences both the critical purge speed and the efficiency of the purging process.
