The relentless drive towards smaller,faster,and more pow-erful electronics has made thermal management a critical bot-tleneck for performance and reliability.For over a century,the thermal conductivity(κ)of metallic ...The relentless drive towards smaller,faster,and more pow-erful electronics has made thermal management a critical bot-tleneck for performance and reliability.For over a century,the thermal conductivity(κ)of metallic materials has long been considered to have an inherent upper limit for thermal conductivity,plateauing~400 W·m^(-1)·K^(-1).This ceiling is rooted in fundamental physics:in typical metals,heat is primarily carried by electrons,and their transport is severely hampered by strong electron-phonon coupling and inherent lat-tice anharmonicity[1].展开更多
High-concentration photovoltaic(HCPV)systems present significant thermal management challenges due to the intense heat fluxes generated under concentrated solar irradiation,especially in arid environments.Effective he...High-concentration photovoltaic(HCPV)systems present significant thermal management challenges due to the intense heat fluxes generated under concentrated solar irradiation,especially in arid environments.Effective heat dissipation is critical to prevent performance degradation and structural failure.This study investigates the thermal performance and design optimization of an enhanced HCPV module,integrating numerical,analytical,and experimental methods.A coupled optical-thermal-electrical model was developed to simulate ray tracing,heat transfer,and temperature-dependent electrical behaviour,with predictions validated under real-world desert conditions.Compared to a baseline commercial module operating at 106℃,the optimized design achieved a peak temperature reduction of 16℃,lowering the cell temperature to 90℃under a concentration ratio of 961×and direct normal irradiance(DNI)of 950 W/m^(2).The total thermal resistance was reduced from 0.25 to 0.15 K/W(a 40%improvement),and the electrical efficiency increased from 37.5%to 38.6%,representing a relative gain of approximately 3.1%.The system consistently maintained a fill factor exceeding 78%,underscoring stable performance under high thermal load.These findings demonstrate that targeted thermal design,informed by integrated modeling,is essential for unlocking the reliability and efficiency of high-flux solar energy systems.展开更多
Typically used thermal insulation materials such as foam insulation and fibreglass may pose notable health risks and environmental impacts thereby resulting in respiratory irritation andwaste disposal issues,respectiv...Typically used thermal insulation materials such as foam insulation and fibreglass may pose notable health risks and environmental impacts thereby resulting in respiratory irritation andwaste disposal issues,respectively.While these materials are affordable and display good thermal insulation,their unsustainable traits pertaining to an intensive manufacturing process and poor disposability are major concerns.Alternative insulation materials with enhanced sustainable characteristics are therefore being explored,and one type of material which has gained notable attention owing to its low carbon footprint and low thermal conductivity is natural fibre.Among the few review studies conducted on Natural Fibre Reinforced Composite(NFRC)insulation boards,the multitude of factors and underlying mechanisms affecting their thermal conductivity performance have been sparsely covered.This review study aimed to address this gap by providing a holistic overview of some of the key intrinsic and extrinsic factors affecting the thermal conductivity performance of NFRCs.Key intrinsic factors pertaining to the microstructural features and to the physico-mechanical traits of NFRCs,namely the fibre lumen size,α,and the fibre-matrix thermal conductivity ratio,β,respectively,were found to largely affect the Transverse Thermal Conductivity(TTC)in NFRC boards.Extrinsic factors,which were found to indirectly affect NFRCs’thermal conductivity,such as fibre pre-processing,composite manufacturing and environmental factors,were also covered.Some of the noteworthy NFRC featureswhich were found to affect their thermal conductivity are volume fraction of fibres,bulk density and porosity.The findings of this study highlight the need for additional research investigation to address the foregoing limitations observed in NFRC thermal insulation boards by considering appropriate natural fibres,composition and fabrication techniques.The fabrication of high-grade NFRC boards,which will display an optimum balance between enhanced thermal insulation and long-term durability performance,could further replace conventionally used thermal insulation boards in the modern building and construction industry.展开更多
Perovskite solar cells(PSCs)have achieved excellent power conversion efficiencies;however,under direct sunlight,device temperatures can exceed ambient temperatures by more than 50℃,making thermal stability a critical...Perovskite solar cells(PSCs)have achieved excellent power conversion efficiencies;however,under direct sunlight,device temperatures can exceed ambient temperatures by more than 50℃,making thermal stability a critical challenge for commercialization.This review first summarizes the degradation mechanisms of PSCs induced by elevated temperatures,followed by a discussion of heat generation,with Joule heat identified as the primary contributor.Advanced thermal management strategies are then highlighted,including the use of high thermal conductivity materials,integration with thermoelectric devices,external radiative cooling layers,down-conversion approaches,and tandem structures.By systematically presenting these strategies,this review provides guidance for enhancing both the efficiency and thermal stability of PSCs,thereby supporting their pathway toward commercialization.展开更多
The increasing penetration of renewable energy sources(RES)imposes stringent flexibility requirements on thermal power units(TPUs).Integrating molten salt thermal storage systems(MSTS)and thermal-electric coupling tec...The increasing penetration of renewable energy sources(RES)imposes stringent flexibility requirements on thermal power units(TPUs).Integrating molten salt thermal storage systems(MSTS)and thermal-electric coupling technologies into TPUs has the potential to improve their operational flexibility and regulation capability.However,existing research seldom investigates the combined effects of MSTS retrofitting and thermal-electric output coupling on short-term dispatchability,especially under rapid load variation conditions.This study proposes a comprehensive modeling and multi-timescale optimization framework for MSTS-retrofitted TPUs with rapid load variation capability,enabling coordinated thermal and electrical dispatch in both day-ahead and real-time stages.The TPU model incorporates steam heating,electric heating,MSTS charge and discharge characteristics,and ladder typer ramping constraints,enabling detailed representation of thermal-electric coupling interactions.The proposed scheduling framework consists of a day-ahead economic dispatch model and a minute-level intraday rolling optimization.In the day-ahead stage,the model maximizes operational revenue while considering flexibility reserve requirements,multi-period peak shaving,reserve allocation,and thermal-electric coupling strategies that coordinate steam and electric heating with MSTS charging and discharging.In the intraday rolling stage,real-time RES fluctuations and load variations are incorporated to update dispatch decisions,ensuring continuous power–heat balance and efficient use of stored thermal energy.Simulation results verify that thermal-electric coupling enhances the system’s capability to maintain real-time power balance,while MSTS operation effectively mitigates output fluctuations and supports stable,economical operation for addressing RES variation.展开更多
Thermal diodes,based on the thermal rectification effect,have demonstrated great promise for advanced thermal management.In previous studies,almost all thermal diodes were discussed under the condition of steady state...Thermal diodes,based on the thermal rectification effect,have demonstrated great promise for advanced thermal management.In previous studies,almost all thermal diodes were discussed under the condition of steady states,while the heat source of a practical thermal system often operates under dynamically fluctuating temperatures.Therefore,in this work,we employ finite element simulation to investigate transient thermal rectification behaviors in a well-built heterojunction which exhibits intrinsic thermal rectification effect under steady state.Unidirectional energy transport in the heterojunction system,decoupled from the steady-state temperature bias,is observed under a time-dependent fluctuating heat source.This phenomenon enables straightforward realization of both giant thermal rectification and negative thermal transport.Furthermore,a series of novel thermal regulation strategies are unveiled by adjusting the average temperature,frequency,and phase of the heat source.Our work not only deepens fundamental understanding of thermal regulation in time-dependent oscillating temperature systems but also uncovers many unexplored energy-saving thermal management strategies.展开更多
To address the challenge of balancing thermal management and thermal runaway mitigation,it is crucial to explore effective methods for enhancing the safety of lithium-ion battery systems.Herein,an innovative hydrated ...To address the challenge of balancing thermal management and thermal runaway mitigation,it is crucial to explore effective methods for enhancing the safety of lithium-ion battery systems.Herein,an innovative hydrated salt composite phase change material(HSCPCM)with dual phase transition temperature zones has been proposed.This HSCPCM,denoted as SDMA10,combines hydrophilic modified expanded graphite,an acrylic emulsion coating,and eutectic hydrated salts to achieve leakage prevention,enhanced thermal stability,cycling stability,and superior phase change behavior.Battery modules incorporating SDMA10 demonstrate significant thermal control capabilities.Specifically,the cylindrical battery modules with SDMA10 can maintain maximum operating temperatures below 55°C at 4 C discharge rate,while prismatic battery modules can keep maximum operating temperatures below 65°C at 2 C discharge rate.In extreme battery overheating conditions simulated using heating plates,SDMA10 effectively suppresses thermal propagation.Even when the central heating plate reaches 300°C,the maximum temperature at the module edge heating plates remains below 85°C.Further,compared to organic composite phase change materials(CPCMs),the battery module with SDMA10 can further reduce the peak thermal runaway temperature by 93°C and delay the thermal runaway trigger time by 689 s,thereby significantly decreasing heat diffusion.Therefore,the designed HSCPCM integrates excellent latent heat storage and thermochemical storage capabilities,providing high thermal energy storage density within the thermal management and thermal runaway threshold temperature range.This research will offer a promising pathway for improving the thermal safety performance of battery packs in electric vehicles and other energy storage systems.展开更多
The in-flight heating process of cerium dioxide(CeO_(2))powders was investigated through experiments and numerical simulations.In the experiment,CeO_(2)powder(average size of 30μm)was injected into radio-frequency(RF...The in-flight heating process of cerium dioxide(CeO_(2))powders was investigated through experiments and numerical simulations.In the experiment,CeO_(2)powder(average size of 30μm)was injected into radio-frequency(RF)argon plasma,and the temperatures were measured using a DPV-2000 monitor.A model combining the electromagnetism,thermal flow,and heat transfer characteristics of powder during in-flight heating in argon plasma was proposed.The melting processes of CeO_(2)powders of different diameters,with and without thermal resistance effect,were investigated.Results show that the heating process of CeO_(2)powder particles consists of three main stages,one of which is relevant to a dimensionless parameter known as the Biot number.When the Biot value≥0.1,thermal resistance increases significantly,especially for the larger powders.The predicted temperature of the particles at the outlet(1800–2880 K)is in good agreement with the experimental result.展开更多
The development of infrared engineering technologies for extreme environments remains a formidable challenge due to the inherent trade-offs among optical performance,thermal stability,and mechanical integrity in therm...The development of infrared engineering technologies for extreme environments remains a formidable challenge due to the inherent trade-offs among optical performance,thermal stability,and mechanical integrity in thermal photonic metamaterials(TPMs).This work introduces a novel multi-obj ective design framework and demonstrates the design,fabrication,and validation of a TPM operating under extreme temperatures up to 1873 K.We have established a holistic design framework integrating temperaturedependent neural network and Pareto multi-obj ective optimization to co-optimize spectral response,component light-weighting,and structural efficiency.The framework achieves 100 times faster computation than genetic algorithms.The performance of the designed TPM was evaluated under various atmospheric models and detection distances.The TPM achieved a peak radiance suppression efficiency of 82%and a maximum attenuation of-7.4 dB at 1200-1500 K.Experimentally,we fabricated an all-dielectric TPM using a refractory TiO_(2)/BeO multilayer stack with only 5 layers and 2um total thickness.The optimized structure shows high reflectivity(0.62 at 3-5 um;0.48 at 8-14μm)for radiative suppression and high emissivity(0.87 at 5-8μm)for radiative cooling.The TPM withstands 1873 K for 12 h in air with less than 3%spectral drift,retaining excellent mechanical properties.On high-temperature components,it achieves 40-50%radiative suppression and 40-60 K(~10.1 kW m^(-2))radiative cooling at 1100 K,endures over 20 times thermal shock cycles(>150 K s^(-1),700-1500 K),and maintains stable performance over 5 cycles,with 78%visible and 98%microwave transmittance.This work establishes a new paradigm in the design and application of photonic materials for extreme environments.展开更多
With the increasing application of lithium-ion batteries under high-rate operation,safety concerns such as thermal runaway(TR)and thermal runaway propagation(TRP)have become critical.In this study,the TRP action of ba...With the increasing application of lithium-ion batteries under high-rate operation,safety concerns such as thermal runaway(TR)and thermal runaway propagation(TRP)have become critical.In this study,the TRP action of batteries undergoing high-rate cycling is systematically investigated.Microanalysis results reveal that the crystallinity and I_((003))/I_((104))of the cathode are decreased by 32.95%and 13.01%after 4 C cycling,while the layered structure of the anode is seriously damaged.As revealed,the TR interval time(At)of batteries cycled at 4 C is decreased by 83.23%compared with that for batteries cycled at 1 C.Meanwhile,the maximum mass loss(ML)rate of Battery 2#is increased by 32.35%.We have further investigated the influence of battery spacing on TRP action.The maximum TR temperature of Battery2#at 1.5 cm spacing is reduced by 26.21%compared with the value at 0 cm spacing.When increasing the spacing from 0 to 1.5 cm,the ML of batteries is reduced by 20.73%.ML increases and decreases with the elevation of the charging rate and battery spacing,respectively.Compared with a battery cycled at1 C,a battery cycled at 4 C shows reduced heat required to trigger TR.The corresponding decreases can reach 68.28%,70.10%,76.88%,and 26.15%when setting the spacing at 0,0.6,1.5,and 2.1 cm,respectively.This indicates that Battery 2#can enter TR with much lower heat after high-rate cycling.Overall,high-rate cycling and low spacing accelerate the TRP of the battery and aggravate the TR severity of the battery.This work can provide insights for the practical safety design of energy storage systems.展开更多
Investigating the damage evolution of surrounding rock under thermal shock cycles is crucial for ensuring the stability of engineering rock masses.This study performed Brazilian splitting tests on granite specimens un...Investigating the damage evolution of surrounding rock under thermal shock cycles is crucial for ensuring the stability of engineering rock masses.This study performed Brazilian splitting tests on granite specimens under varying temperature and cycle conditions,employing acoustic emission monitoring,digital image correlation,and three-dimensional scanning technology.A systematic analysis was conducted on the patterns of damage evolution,failure precursor,and response mechanisms under combined thermal and cyclic loading.Experimental results show that both P-wave velocity and tensile strength degrade significantly with increasing temperature and cycle count,with temperature having a more pronounced effect than cycle count.Notably,damage evolution exhibits a dual-threshold behavior in which degradation accelerates markedly above 400℃ and stabilizes after 5 thermal cycles.Fracture surfaces evolve from initially planar to rugged morphologies,with peak-valley height differences at 600℃ being approximately three times greater than those at 200℃.Furthermore,based on acoustic emission energy entropy analysis,we introduce a novel failure precursor indicator where the sustained increase and critical surge in average entropy serve as reliable early-warning signals for impending rock failure.These findings establish a solid theoretical basis and practical methodology for damage assessment and instability early-warning systems in high-temperature rock engineering.展开更多
The effect of real-time high temperature and thermal treatment on the mechanical characteristics and crack evolution of granite with different grain sizes(i.e.,0.5 mm,0.7 mm and 1.0 mm)is investigated by numerical sim...The effect of real-time high temperature and thermal treatment on the mechanical characteristics and crack evolution of granite with different grain sizes(i.e.,0.5 mm,0.7 mm and 1.0 mm)is investigated by numerical simulation employing a grain-based model,and the impact of initial cracks on thermal-induced strengthening is also examined by integrating random cracks within the model before tests.The results revealed that thermal stress,induced by the mismatch in thermal expansion coefficient between various minerals,is the primary distinction between rock specimens in real-time high temperature and thermal treatment.With increasing temperature,the thermal stress gradually accumulates in quartz minerals under real-time high temperature but releases after thermal treatment.The high local contact force significantly affects the peak stress and crack evolution.Uniaxial compression simulation results demonstrate that progressive accumulation of thermal stress induces degradation in macroscopic peak strength and increase of microcrack density.The grain size controls the ratio of intergranular contacts to intragranular contacts,and leads to an increase in strong contact number in the intragrain and a decrease in strong contact number in the intergrain.The strengthening of uniaxial compression strength in the experiment can be well simulated by controlling the number of pre-existing initial cracks in the numerical model.Our conclusions are beneficial to a better understanding of the underlying mechanisms of thermal damage and thermal strengthening of granite for deep geological engineering.展开更多
There is an urgent need to develop magnesium-matrix materials that exhibit both high thermal conductivity and low thermal expansion to ensure compatibility with chips.This study aims to develop a Mg-Zn-Cu alloy with h...There is an urgent need to develop magnesium-matrix materials that exhibit both high thermal conductivity and low thermal expansion to ensure compatibility with chips.This study aims to develop a Mg-Zn-Cu alloy with high thermal conductivity.Furthermore,it explores the preparation of AlN_(P)/Mg-Zn-Cu composites featuring low coefficients of thermal expansion.The stir casting method was utilized to fabricate the composites and an investigation was conducted to examine their microstructure and thermal properties.Results indicate that the addition of AlN_(P)reduces the thermal expansion coefficient while maintaining relatively high thermal conductivity.Specifically,the AlN_(P)/Mg-0.5Zn-0.5Cu composite with 30wt.%AlN_(P)achieves a thermal conductivity of 132.7 W·m^(-1)·K^(-1)and a thermal expansion coefficient of 18.5×10^(-6)K^(-1),rendering it suitable for electronic packaging applications where thermal management is critical.展开更多
The utilisation of waste in green sustainable technology can provide a clean environment and support energy demand.This work aims to design and analyse the performance of a developed indirect flat-plate Solar Air Heat...The utilisation of waste in green sustainable technology can provide a clean environment and support energy demand.This work aims to design and analyse the performance of a developed indirect flat-plate Solar Air Heater(SAH)integrated with an internal thermal storage unit using Waste Automotive Oil(WAO).The SAH was designed based on the circulation of confined air around the internal thermal storage unit due to the updraft effects of hot air.Two SAHs were tested to compare the performance of WAO and water,with the results being compared to previous work that utilised phase change material.Results showed that WAO responds faster in the early stage,while water has slightly higher daytime efficiency,with a maximum temperature of 60℃,while WAO reached a maximum temperature of 76℃.During the discharge cycle,WAO achieved an efficiency of 65.7%,while the water’s efficiency 73.2% within the same period.The highest outlet air temperatures recorded were 43℃ for WAO and 33.8℃ for water.These findings support that water is suitable for applications requiring rapid thermal charging,while WAO offers extended thermal stability.The study highlights the feasibility of using low-cost materials,such as WAO and water,to enhance the performance of solar energy systems,thereby making them more viable for industrial applications like drying and heating.展开更多
High rock temperature is a great challenge frequently encountered during subsurface resource recovery and deep underground space utilization,and it is still unclear how the granitic rock responds to realtime high temp...High rock temperature is a great challenge frequently encountered during subsurface resource recovery and deep underground space utilization,and it is still unclear how the granitic rock responds to realtime high temperature upon shear loading.To better understand the shear fracture behavior and underlying processes of intact granite exposed to thermal-mechanical coupling loading,direct shear tests were conducted utilizing a newly built testing apparatus at varied normal stresses and high temperatures.Influencesof different temperatures and different heating methods(real-time heating and thermal treatment)on the shear mechanical behavior were compared and discussed.Results indicate that shear stress fluctuationswith some small stress drops occur as shear stress is approaching the peak strength under real-time heating,accompanied by more and earlier AE signal uprushes.This suggests that greater cracking events occur earlier during real-time heating than after thermal treatment,resulting in a lower peak shear strength.Furthermore,the peak shear strength,post-peak stress drop,and cohesion rise from room temperature(RT)to 200℃(the peak strength increases by 8%,5.8%,and 9.9%under normal stress of 5 MPa,15 MPa,and 20 MPa,correspondingly),and subsequently decline from 200℃to 400℃.Temperature has a limited impact on shear stiffness from RT to 200℃,but significantlyreduces it from 200℃to 400℃,with drops of 15%,7.9%,and 10%under normal stress of 5 MPa,15 MPa,and 20 MPa,respectively.Moreover,the shear strength and stiffness under real-time heating are lower than those for the thermally treated specimens.The strengthening of intact granite below 200℃upon shear is associated with loss of water and a more compacted structure,while the weakening effect of temperature on shear strength from 200℃to 400℃is due to the new thermal cracks and less brittle and stiff of minerals.展开更多
The geothermal resources in China are primarily found in its sedimentary basins,particularly in the large basins located in eastern China,which hold significant potential for geothermal energy development.The Songliao...The geothermal resources in China are primarily found in its sedimentary basins,particularly in the large basins located in eastern China,which hold significant potential for geothermal energy development.The Songliao,North China,and Zhangzhou basins are of special interest due to their considerable exploration depths,extensive development history,and high levels of research activity.This study focuses on the three basins to analyze their thermal reservoir characteristics in eastern China.Between 2017 and 2023,the research team carried out a comprehensive analysis involving deep boreholes that exceeded 4000 m in depth within these three basins.They meticulously created detailed physical profiles that captured essential characteristics such as porosity,permeability,and thermal properties,reaching down to the basement of each basin.The findings indicated that variations in thermal conductivity within shallow geotechnical layers significantly influence the redistribution of deep thermal energy in the upper layers of the earth.Furthermore,differences in physical properties notably affect heat transport processes.The research proposes distinct heat models tailored for each basin:For the Songliao Basin,a low-permeability model with homogeneous thermal properties is constructed;for the North China Basin,high permeability and thermal conductivity layers are highlighted;and a fracture network controlling water and heat is presented in the Zhangzhou Basin.To elucidate the thermal structure of these basins,the Curie surface and Moho surface were analyzed.The shallow Curie surface indicates ongoing intense thermal activity stemming from crustal heat sources,while a shallow Moho surface signifies historical vigorous mantle thermal activity associated with mantle source heat production.Furthermore,the research evaluates the geothermal resources and the potential for carbon emission reduction in these basins.Total volume of exploitable geothermal fluid is estimated to be 76.9×10^(9) m^(3)/a,corresponding to an annual renewable geothermal energy 1.47×10^(16)k J.The implementation of geothermal energy could lead to a reduction in annual CO_(2)emissions by nearly 2×10^(9) t,which constitutes about 17.4%of China’s national carbon emissions in 2022.This estimation provides invaluable theoretical insights and data support for geothermal exploration and sustainable development in eastern China.展开更多
The effect of element Ti on the microstructures and mechanical properties of as-cast and annealed NbTaMoWTi,(x=0,1,1.5,2)refractory high-entropy alloys(RHEAs)was investigated.Results show that after Ti addition,the as...The effect of element Ti on the microstructures and mechanical properties of as-cast and annealed NbTaMoWTi,(x=0,1,1.5,2)refractory high-entropy alloys(RHEAs)was investigated.Results show that after Ti addition,the as-cast alloys maintain their original single body-centered cubic(bcc)structure.As for the mechanical properties,compared with those without Ti addition,the strength and ductility of NbTaMoWTi,alloys increase by 93%and 215%,respectively.Furthermore,the NbTaMoWTi alloys exhibit outstanding thermal stability.After annealing at 1400 C,they still maintain the single bcc structure,and their mechanical properties are even slightly improved.However,annealing leads to a significant deterioration in the mechanical properties of high-Ti-content alloys(NbTaMoWTil and NbTaMoWTi2),owing to the formation of Ti-rich acicular phases.展开更多
Six new lanthanide complexes:[Ln(3,4-DEOBA)3(4,4'-DM-2,2'-bipy)]2·2C_(2)H_(5)OH,[Ln=Dy(1),Eu(2),Tb(3),Sm(4),Ho(5),Gd(6);3,4-DEOBA-=3,4-diethoxybenzoate,4,4'-DM-2,2'-bipy=4,4'-dimethyl-2,2'...Six new lanthanide complexes:[Ln(3,4-DEOBA)3(4,4'-DM-2,2'-bipy)]2·2C_(2)H_(5)OH,[Ln=Dy(1),Eu(2),Tb(3),Sm(4),Ho(5),Gd(6);3,4-DEOBA-=3,4-diethoxybenzoate,4,4'-DM-2,2'-bipy=4,4'-dimethyl-2,2'-bipyridine]were successfully synthesized by the volatilization of the solution at room temperature.The crystal structures of six complexes were determined by single-crystal X-ray diffraction technology.The results showed that the complexes all have a binuclear structure,and the structures contain free ethanol molecules.Moreover,the coordination number of the central metal of each structural unit is eight.Adjacent structural units interact with each other through hydrogen bonds and further expand to form 1D chain-like and 2D planar structures.After conducting a systematic study on the luminescence properties of complexes 1-4,their emission and excitation spectra were obtained.Experimental results indicated that the fluorescence lifetimes of complexes 2 and 3 were 0.807 and 0.845 ms,respectively.The emission spectral data of complexes 1-4 were imported into the CIE chromaticity coordinate system,and their corre sponding luminescent regions cover the yellow light,red light,green light,and orange-red light bands,respectively.Within the temperature range of 299.15-1300 K,the thermal decomposition processes of the six complexes were comprehensively analyzed by using TG-DSC/FTIR/MS technology.The hypothesis of the gradual loss of ligand groups during the decomposition process was verified by detecting the escaped gas,3D infrared spectroscopy,and ion fragment information detected by mass spectrometry.The specific decomposition path is as follows:firstly,free ethanol molecules and neutral ligands are removed,and finally,acidic ligands are released;the final product is the corresponding metal oxide.CCDC:2430420,1;2430422,2;2430419,3;2430424,4;2430421,5;2430423,6.展开更多
The present work provides a facile and efficient method for producing ultrafine copper powders.Ultrafine copper powders were synthesized through a solvothermal method,utilizing ethanol both as a solvent and a reducing...The present work provides a facile and efficient method for producing ultrafine copper powders.Ultrafine copper powders were synthesized through a solvothermal method,utilizing ethanol both as a solvent and a reducing agent.Specifically,by exploiting the weak reducing property of ethanol,the copper precursor is first converted to copper oxide and then further reduced to cuprous oxide and pure copper.Such a method can effectively control the morphology and particle size of the copper powder,reduce particle aggregation,and enhance oxidation resistance.It is cost-effective and produces fewer toxic by-products.Spherical copper particles with an average particle size of about 180 nm were obtained.The initial oxidation temperature is approximately 150℃,and the resulting copper powders can be stored stably under ambient conditions for at least 5 months,demonstrating excellent oxidation resistance and thermal stability.展开更多
A multi-physics approach was used to quantify the effect of process parameters (laser power, scanning speed, hatch spacing, and scanning strategy) on the thermal history and corresponding microstructure evolution of T...A multi-physics approach was used to quantify the effect of process parameters (laser power, scanning speed, hatch spacing, and scanning strategy) on the thermal history and corresponding microstructure evolution of Ti-25Nb (at%) alloy during the dual-track selective laser melting (SLM) process. Simulation results reveal that during the dual-track SLM process, increasing laser power results in greater thermal accumulation, leading to a molten pool of larger volume and coarser grains. Reducing scanning speed enhances remelting and promotes cellular growth at the top of molten pool, whereas faster scanning speed leads to rougher melt tracks and finer grains. Notably, hatch spacing significantly influences the molten pool dimensions and microstructures, and smaller hatch spacing promotes remelting. Furthermore, the orientations of grains in the second track during zigzag scanning differ markedly from those in the first track. More importantly, compared with those after the first track, both the temperature gradient and cooling rate at the boundaries of remelting molten pool are reduced after the second track scanning, resulting in slower interface velocity and significant change in solidification microstructure. This research provides a theoretical foundation for controlling non-equilibrium microstructure and offering novel insights into the optimization of SLM process parameters of titanium alloys.展开更多
文摘The relentless drive towards smaller,faster,and more pow-erful electronics has made thermal management a critical bot-tleneck for performance and reliability.For over a century,the thermal conductivity(κ)of metallic materials has long been considered to have an inherent upper limit for thermal conductivity,plateauing~400 W·m^(-1)·K^(-1).This ceiling is rooted in fundamental physics:in typical metals,heat is primarily carried by electrons,and their transport is severely hampered by strong electron-phonon coupling and inherent lat-tice anharmonicity[1].
基金funded by King Abdullah City for Atomic and Renewable Energy(KACARE),grant number“PC-2020-1”.
文摘High-concentration photovoltaic(HCPV)systems present significant thermal management challenges due to the intense heat fluxes generated under concentrated solar irradiation,especially in arid environments.Effective heat dissipation is critical to prevent performance degradation and structural failure.This study investigates the thermal performance and design optimization of an enhanced HCPV module,integrating numerical,analytical,and experimental methods.A coupled optical-thermal-electrical model was developed to simulate ray tracing,heat transfer,and temperature-dependent electrical behaviour,with predictions validated under real-world desert conditions.Compared to a baseline commercial module operating at 106℃,the optimized design achieved a peak temperature reduction of 16℃,lowering the cell temperature to 90℃under a concentration ratio of 961×and direct normal irradiance(DNI)of 950 W/m^(2).The total thermal resistance was reduced from 0.25 to 0.15 K/W(a 40%improvement),and the electrical efficiency increased from 37.5%to 38.6%,representing a relative gain of approximately 3.1%.The system consistently maintained a fill factor exceeding 78%,underscoring stable performance under high thermal load.These findings demonstrate that targeted thermal design,informed by integrated modeling,is essential for unlocking the reliability and efficiency of high-flux solar energy systems.
文摘Typically used thermal insulation materials such as foam insulation and fibreglass may pose notable health risks and environmental impacts thereby resulting in respiratory irritation andwaste disposal issues,respectively.While these materials are affordable and display good thermal insulation,their unsustainable traits pertaining to an intensive manufacturing process and poor disposability are major concerns.Alternative insulation materials with enhanced sustainable characteristics are therefore being explored,and one type of material which has gained notable attention owing to its low carbon footprint and low thermal conductivity is natural fibre.Among the few review studies conducted on Natural Fibre Reinforced Composite(NFRC)insulation boards,the multitude of factors and underlying mechanisms affecting their thermal conductivity performance have been sparsely covered.This review study aimed to address this gap by providing a holistic overview of some of the key intrinsic and extrinsic factors affecting the thermal conductivity performance of NFRCs.Key intrinsic factors pertaining to the microstructural features and to the physico-mechanical traits of NFRCs,namely the fibre lumen size,α,and the fibre-matrix thermal conductivity ratio,β,respectively,were found to largely affect the Transverse Thermal Conductivity(TTC)in NFRC boards.Extrinsic factors,which were found to indirectly affect NFRCs’thermal conductivity,such as fibre pre-processing,composite manufacturing and environmental factors,were also covered.Some of the noteworthy NFRC featureswhich were found to affect their thermal conductivity are volume fraction of fibres,bulk density and porosity.The findings of this study highlight the need for additional research investigation to address the foregoing limitations observed in NFRC thermal insulation boards by considering appropriate natural fibres,composition and fabrication techniques.The fabrication of high-grade NFRC boards,which will display an optimum balance between enhanced thermal insulation and long-term durability performance,could further replace conventionally used thermal insulation boards in the modern building and construction industry.
基金the National Natural Science Foundation of China(Nos.62574037,62374029,22175029,62474033 and W2433038)the Young EliteScientists Sponsorship Program by CAST(No.YES S20220550)+2 种基金the Sichuan Science and Technology Program(No.2024NSFSC0250)the Guangdong Basic and Applied Basic Research Foundation(No.2025A1515010313)the Fundamental Research Funds for the Central Universities of China(No.ZYGX2022J032)for financial support。
文摘Perovskite solar cells(PSCs)have achieved excellent power conversion efficiencies;however,under direct sunlight,device temperatures can exceed ambient temperatures by more than 50℃,making thermal stability a critical challenge for commercialization.This review first summarizes the degradation mechanisms of PSCs induced by elevated temperatures,followed by a discussion of heat generation,with Joule heat identified as the primary contributor.Advanced thermal management strategies are then highlighted,including the use of high thermal conductivity materials,integration with thermoelectric devices,external radiative cooling layers,down-conversion approaches,and tandem structures.By systematically presenting these strategies,this review provides guidance for enhancing both the efficiency and thermal stability of PSCs,thereby supporting their pathway toward commercialization.
基金funded by State Grid Jiangsu Electric Power Co.,Ltd.Science and Technology Project,grant number J2023118.
文摘The increasing penetration of renewable energy sources(RES)imposes stringent flexibility requirements on thermal power units(TPUs).Integrating molten salt thermal storage systems(MSTS)and thermal-electric coupling technologies into TPUs has the potential to improve their operational flexibility and regulation capability.However,existing research seldom investigates the combined effects of MSTS retrofitting and thermal-electric output coupling on short-term dispatchability,especially under rapid load variation conditions.This study proposes a comprehensive modeling and multi-timescale optimization framework for MSTS-retrofitted TPUs with rapid load variation capability,enabling coordinated thermal and electrical dispatch in both day-ahead and real-time stages.The TPU model incorporates steam heating,electric heating,MSTS charge and discharge characteristics,and ladder typer ramping constraints,enabling detailed representation of thermal-electric coupling interactions.The proposed scheduling framework consists of a day-ahead economic dispatch model and a minute-level intraday rolling optimization.In the day-ahead stage,the model maximizes operational revenue while considering flexibility reserve requirements,multi-period peak shaving,reserve allocation,and thermal-electric coupling strategies that coordinate steam and electric heating with MSTS charging and discharging.In the intraday rolling stage,real-time RES fluctuations and load variations are incorporated to update dispatch decisions,ensuring continuous power–heat balance and efficient use of stored thermal energy.Simulation results verify that thermal-electric coupling enhances the system’s capability to maintain real-time power balance,while MSTS operation effectively mitigates output fluctuations and supports stable,economical operation for addressing RES variation.
基金supported by the National Key Research and Development Program of China(Grant No.2023YFA1407001)Department of Science and Technology of Jiangsu Province(Grant No.BK20220032)。
文摘Thermal diodes,based on the thermal rectification effect,have demonstrated great promise for advanced thermal management.In previous studies,almost all thermal diodes were discussed under the condition of steady states,while the heat source of a practical thermal system often operates under dynamically fluctuating temperatures.Therefore,in this work,we employ finite element simulation to investigate transient thermal rectification behaviors in a well-built heterojunction which exhibits intrinsic thermal rectification effect under steady state.Unidirectional energy transport in the heterojunction system,decoupled from the steady-state temperature bias,is observed under a time-dependent fluctuating heat source.This phenomenon enables straightforward realization of both giant thermal rectification and negative thermal transport.Furthermore,a series of novel thermal regulation strategies are unveiled by adjusting the average temperature,frequency,and phase of the heat source.Our work not only deepens fundamental understanding of thermal regulation in time-dependent oscillating temperature systems but also uncovers many unexplored energy-saving thermal management strategies.
基金financially supported by Natural Science Foundation of Guangdong province(2024A1515010228)CATARC Automotive Inspection Center Excellent Engineer Program(2023B0909050007).
文摘To address the challenge of balancing thermal management and thermal runaway mitigation,it is crucial to explore effective methods for enhancing the safety of lithium-ion battery systems.Herein,an innovative hydrated salt composite phase change material(HSCPCM)with dual phase transition temperature zones has been proposed.This HSCPCM,denoted as SDMA10,combines hydrophilic modified expanded graphite,an acrylic emulsion coating,and eutectic hydrated salts to achieve leakage prevention,enhanced thermal stability,cycling stability,and superior phase change behavior.Battery modules incorporating SDMA10 demonstrate significant thermal control capabilities.Specifically,the cylindrical battery modules with SDMA10 can maintain maximum operating temperatures below 55°C at 4 C discharge rate,while prismatic battery modules can keep maximum operating temperatures below 65°C at 2 C discharge rate.In extreme battery overheating conditions simulated using heating plates,SDMA10 effectively suppresses thermal propagation.Even when the central heating plate reaches 300°C,the maximum temperature at the module edge heating plates remains below 85°C.Further,compared to organic composite phase change materials(CPCMs),the battery module with SDMA10 can further reduce the peak thermal runaway temperature by 93°C and delay the thermal runaway trigger time by 689 s,thereby significantly decreasing heat diffusion.Therefore,the designed HSCPCM integrates excellent latent heat storage and thermochemical storage capabilities,providing high thermal energy storage density within the thermal management and thermal runaway threshold temperature range.This research will offer a promising pathway for improving the thermal safety performance of battery packs in electric vehicles and other energy storage systems.
基金National Natural Science Foundation of China(11875039)Shanxi Scholarship Council of China(2023-033)+2 种基金Fundamental Research Program of Shanxi Province(202303021221071)China Baowu Low Carbon Metallurgical Innovation Foundation(2022)2023 Anhui Major Industrial Innovation Plan Project。
文摘The in-flight heating process of cerium dioxide(CeO_(2))powders was investigated through experiments and numerical simulations.In the experiment,CeO_(2)powder(average size of 30μm)was injected into radio-frequency(RF)argon plasma,and the temperatures were measured using a DPV-2000 monitor.A model combining the electromagnetism,thermal flow,and heat transfer characteristics of powder during in-flight heating in argon plasma was proposed.The melting processes of CeO_(2)powders of different diameters,with and without thermal resistance effect,were investigated.Results show that the heating process of CeO_(2)powder particles consists of three main stages,one of which is relevant to a dimensionless parameter known as the Biot number.When the Biot value≥0.1,thermal resistance increases significantly,especially for the larger powders.The predicted temperature of the particles at the outlet(1800–2880 K)is in good agreement with the experimental result.
基金supported by National Key Research and Development Program of China(2024YFA1210500,2023YFB4606105)Fundamental Research Center Projects(52488301)of National Natural Science Foundation of China(NSFC)+1 种基金Key Research Program of Frontier Sciences(ZDBS-LYJSC030)of Chinese Academy of SciencesWestern Light Program(xbzg-zdsys-202402)of Chinese Academy of Sciences。
文摘The development of infrared engineering technologies for extreme environments remains a formidable challenge due to the inherent trade-offs among optical performance,thermal stability,and mechanical integrity in thermal photonic metamaterials(TPMs).This work introduces a novel multi-obj ective design framework and demonstrates the design,fabrication,and validation of a TPM operating under extreme temperatures up to 1873 K.We have established a holistic design framework integrating temperaturedependent neural network and Pareto multi-obj ective optimization to co-optimize spectral response,component light-weighting,and structural efficiency.The framework achieves 100 times faster computation than genetic algorithms.The performance of the designed TPM was evaluated under various atmospheric models and detection distances.The TPM achieved a peak radiance suppression efficiency of 82%and a maximum attenuation of-7.4 dB at 1200-1500 K.Experimentally,we fabricated an all-dielectric TPM using a refractory TiO_(2)/BeO multilayer stack with only 5 layers and 2um total thickness.The optimized structure shows high reflectivity(0.62 at 3-5 um;0.48 at 8-14μm)for radiative suppression and high emissivity(0.87 at 5-8μm)for radiative cooling.The TPM withstands 1873 K for 12 h in air with less than 3%spectral drift,retaining excellent mechanical properties.On high-temperature components,it achieves 40-50%radiative suppression and 40-60 K(~10.1 kW m^(-2))radiative cooling at 1100 K,endures over 20 times thermal shock cycles(>150 K s^(-1),700-1500 K),and maintains stable performance over 5 cycles,with 78%visible and 98%microwave transmittance.This work establishes a new paradigm in the design and application of photonic materials for extreme environments.
基金supported by the National Key Research and Development Plan(2023YFC30099000)the National Natural Science Foundation of China(52104197,52272396,52474233)+2 种基金the Major Basic Research Project of the Natural Science Foundation of the Jiangsu Higher Education Institutions(2020240521)the Open Fund of the State Key Laboratory of Fire Science(SKLFS)Program(HZ2025-KF03)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(SJCX25_0595)。
文摘With the increasing application of lithium-ion batteries under high-rate operation,safety concerns such as thermal runaway(TR)and thermal runaway propagation(TRP)have become critical.In this study,the TRP action of batteries undergoing high-rate cycling is systematically investigated.Microanalysis results reveal that the crystallinity and I_((003))/I_((104))of the cathode are decreased by 32.95%and 13.01%after 4 C cycling,while the layered structure of the anode is seriously damaged.As revealed,the TR interval time(At)of batteries cycled at 4 C is decreased by 83.23%compared with that for batteries cycled at 1 C.Meanwhile,the maximum mass loss(ML)rate of Battery 2#is increased by 32.35%.We have further investigated the influence of battery spacing on TRP action.The maximum TR temperature of Battery2#at 1.5 cm spacing is reduced by 26.21%compared with the value at 0 cm spacing.When increasing the spacing from 0 to 1.5 cm,the ML of batteries is reduced by 20.73%.ML increases and decreases with the elevation of the charging rate and battery spacing,respectively.Compared with a battery cycled at1 C,a battery cycled at 4 C shows reduced heat required to trigger TR.The corresponding decreases can reach 68.28%,70.10%,76.88%,and 26.15%when setting the spacing at 0,0.6,1.5,and 2.1 cm,respectively.This indicates that Battery 2#can enter TR with much lower heat after high-rate cycling.Overall,high-rate cycling and low spacing accelerate the TRP of the battery and aggravate the TR severity of the battery.This work can provide insights for the practical safety design of energy storage systems.
基金supported by National Natural Science Foundation of China (Nos.52264006,52364004,and 52464005)the Guizhou Provincial Science and Technology Foundation (No.GCC[2022]005-1)。
文摘Investigating the damage evolution of surrounding rock under thermal shock cycles is crucial for ensuring the stability of engineering rock masses.This study performed Brazilian splitting tests on granite specimens under varying temperature and cycle conditions,employing acoustic emission monitoring,digital image correlation,and three-dimensional scanning technology.A systematic analysis was conducted on the patterns of damage evolution,failure precursor,and response mechanisms under combined thermal and cyclic loading.Experimental results show that both P-wave velocity and tensile strength degrade significantly with increasing temperature and cycle count,with temperature having a more pronounced effect than cycle count.Notably,damage evolution exhibits a dual-threshold behavior in which degradation accelerates markedly above 400℃ and stabilizes after 5 thermal cycles.Fracture surfaces evolve from initially planar to rugged morphologies,with peak-valley height differences at 600℃ being approximately three times greater than those at 200℃.Furthermore,based on acoustic emission energy entropy analysis,we introduce a novel failure precursor indicator where the sustained increase and critical surge in average entropy serve as reliable early-warning signals for impending rock failure.These findings establish a solid theoretical basis and practical methodology for damage assessment and instability early-warning systems in high-temperature rock engineering.
基金Project(51879135)supported by the Taishan Scholars Program,ChinaProject(52309130)supported by the National Natural Science Foundation of China+1 种基金Project(SKLGME023003)supported by the Open Research Fund of State Key Laboratory of Geomechanics and Geotechnical Engineering Safety,ChinaProject(2022AH051754)supported by the Natural Science Research Project of Anhui Universities,China。
文摘The effect of real-time high temperature and thermal treatment on the mechanical characteristics and crack evolution of granite with different grain sizes(i.e.,0.5 mm,0.7 mm and 1.0 mm)is investigated by numerical simulation employing a grain-based model,and the impact of initial cracks on thermal-induced strengthening is also examined by integrating random cracks within the model before tests.The results revealed that thermal stress,induced by the mismatch in thermal expansion coefficient between various minerals,is the primary distinction between rock specimens in real-time high temperature and thermal treatment.With increasing temperature,the thermal stress gradually accumulates in quartz minerals under real-time high temperature but releases after thermal treatment.The high local contact force significantly affects the peak stress and crack evolution.Uniaxial compression simulation results demonstrate that progressive accumulation of thermal stress induces degradation in macroscopic peak strength and increase of microcrack density.The grain size controls the ratio of intergranular contacts to intragranular contacts,and leads to an increase in strong contact number in the intragrain and a decrease in strong contact number in the intergrain.The strengthening of uniaxial compression strength in the experiment can be well simulated by controlling the number of pre-existing initial cracks in the numerical model.Our conclusions are beneficial to a better understanding of the underlying mechanisms of thermal damage and thermal strengthening of granite for deep geological engineering.
基金financially supported by National Natural Science Foundation of China(No.52175321)the Fund of Key Laboratory of High Temperature Electromagnetic Materials and Structure of MOE(No.KB202505)。
文摘There is an urgent need to develop magnesium-matrix materials that exhibit both high thermal conductivity and low thermal expansion to ensure compatibility with chips.This study aims to develop a Mg-Zn-Cu alloy with high thermal conductivity.Furthermore,it explores the preparation of AlN_(P)/Mg-Zn-Cu composites featuring low coefficients of thermal expansion.The stir casting method was utilized to fabricate the composites and an investigation was conducted to examine their microstructure and thermal properties.Results indicate that the addition of AlN_(P)reduces the thermal expansion coefficient while maintaining relatively high thermal conductivity.Specifically,the AlN_(P)/Mg-0.5Zn-0.5Cu composite with 30wt.%AlN_(P)achieves a thermal conductivity of 132.7 W·m^(-1)·K^(-1)and a thermal expansion coefficient of 18.5×10^(-6)K^(-1),rendering it suitable for electronic packaging applications where thermal management is critical.
文摘The utilisation of waste in green sustainable technology can provide a clean environment and support energy demand.This work aims to design and analyse the performance of a developed indirect flat-plate Solar Air Heater(SAH)integrated with an internal thermal storage unit using Waste Automotive Oil(WAO).The SAH was designed based on the circulation of confined air around the internal thermal storage unit due to the updraft effects of hot air.Two SAHs were tested to compare the performance of WAO and water,with the results being compared to previous work that utilised phase change material.Results showed that WAO responds faster in the early stage,while water has slightly higher daytime efficiency,with a maximum temperature of 60℃,while WAO reached a maximum temperature of 76℃.During the discharge cycle,WAO achieved an efficiency of 65.7%,while the water’s efficiency 73.2% within the same period.The highest outlet air temperatures recorded were 43℃ for WAO and 33.8℃ for water.These findings support that water is suitable for applications requiring rapid thermal charging,while WAO offers extended thermal stability.The study highlights the feasibility of using low-cost materials,such as WAO and water,to enhance the performance of solar energy systems,thereby making them more viable for industrial applications like drying and heating.
基金support from the Taishan Scholars Program,Key Research Program of Frontier Sciences,Chinese Academy of Sciences(CAS),Grant No.ZDBS-LY-DQC022Open Research Fund of State Key Laboratory of Geomechanics and Geotechnical Engineering Safety,Grant No.SKLGME023003.
文摘High rock temperature is a great challenge frequently encountered during subsurface resource recovery and deep underground space utilization,and it is still unclear how the granitic rock responds to realtime high temperature upon shear loading.To better understand the shear fracture behavior and underlying processes of intact granite exposed to thermal-mechanical coupling loading,direct shear tests were conducted utilizing a newly built testing apparatus at varied normal stresses and high temperatures.Influencesof different temperatures and different heating methods(real-time heating and thermal treatment)on the shear mechanical behavior were compared and discussed.Results indicate that shear stress fluctuationswith some small stress drops occur as shear stress is approaching the peak strength under real-time heating,accompanied by more and earlier AE signal uprushes.This suggests that greater cracking events occur earlier during real-time heating than after thermal treatment,resulting in a lower peak shear strength.Furthermore,the peak shear strength,post-peak stress drop,and cohesion rise from room temperature(RT)to 200℃(the peak strength increases by 8%,5.8%,and 9.9%under normal stress of 5 MPa,15 MPa,and 20 MPa,correspondingly),and subsequently decline from 200℃to 400℃.Temperature has a limited impact on shear stiffness from RT to 200℃,but significantlyreduces it from 200℃to 400℃,with drops of 15%,7.9%,and 10%under normal stress of 5 MPa,15 MPa,and 20 MPa,respectively.Moreover,the shear strength and stiffness under real-time heating are lower than those for the thermally treated specimens.The strengthening of intact granite below 200℃upon shear is associated with loss of water and a more compacted structure,while the weakening effect of temperature on shear strength from 200℃to 400℃is due to the new thermal cracks and less brittle and stiff of minerals.
基金funded by the Basic Scientific Research of China Geological Academy(YK202305)National Key R&D Program of China(2019YFB1504101)+1 种基金National Natural Science Foundation of China(41602271)China Geological Survey(DD20160207 and DD20189112)。
文摘The geothermal resources in China are primarily found in its sedimentary basins,particularly in the large basins located in eastern China,which hold significant potential for geothermal energy development.The Songliao,North China,and Zhangzhou basins are of special interest due to their considerable exploration depths,extensive development history,and high levels of research activity.This study focuses on the three basins to analyze their thermal reservoir characteristics in eastern China.Between 2017 and 2023,the research team carried out a comprehensive analysis involving deep boreholes that exceeded 4000 m in depth within these three basins.They meticulously created detailed physical profiles that captured essential characteristics such as porosity,permeability,and thermal properties,reaching down to the basement of each basin.The findings indicated that variations in thermal conductivity within shallow geotechnical layers significantly influence the redistribution of deep thermal energy in the upper layers of the earth.Furthermore,differences in physical properties notably affect heat transport processes.The research proposes distinct heat models tailored for each basin:For the Songliao Basin,a low-permeability model with homogeneous thermal properties is constructed;for the North China Basin,high permeability and thermal conductivity layers are highlighted;and a fracture network controlling water and heat is presented in the Zhangzhou Basin.To elucidate the thermal structure of these basins,the Curie surface and Moho surface were analyzed.The shallow Curie surface indicates ongoing intense thermal activity stemming from crustal heat sources,while a shallow Moho surface signifies historical vigorous mantle thermal activity associated with mantle source heat production.Furthermore,the research evaluates the geothermal resources and the potential for carbon emission reduction in these basins.Total volume of exploitable geothermal fluid is estimated to be 76.9×10^(9) m^(3)/a,corresponding to an annual renewable geothermal energy 1.47×10^(16)k J.The implementation of geothermal energy could lead to a reduction in annual CO_(2)emissions by nearly 2×10^(9) t,which constitutes about 17.4%of China’s national carbon emissions in 2022.This estimation provides invaluable theoretical insights and data support for geothermal exploration and sustainable development in eastern China.
基金National Natural Science Foundation of China(51774179)Natural Science Foundation of Liaoning Province(20180550546)+2 种基金Joint Fund of State Key Laboratory of Metal Material for Marine Equipment and Application(HGSKL-USTLN(2021)03)High-Level Talent Fund of USTL(6003000377,6003000294)supported by Liaoning Provincial Department of Education(LJ212410146037)。
文摘The effect of element Ti on the microstructures and mechanical properties of as-cast and annealed NbTaMoWTi,(x=0,1,1.5,2)refractory high-entropy alloys(RHEAs)was investigated.Results show that after Ti addition,the as-cast alloys maintain their original single body-centered cubic(bcc)structure.As for the mechanical properties,compared with those without Ti addition,the strength and ductility of NbTaMoWTi,alloys increase by 93%and 215%,respectively.Furthermore,the NbTaMoWTi alloys exhibit outstanding thermal stability.After annealing at 1400 C,they still maintain the single bcc structure,and their mechanical properties are even slightly improved.However,annealing leads to a significant deterioration in the mechanical properties of high-Ti-content alloys(NbTaMoWTil and NbTaMoWTi2),owing to the formation of Ti-rich acicular phases.
文摘Six new lanthanide complexes:[Ln(3,4-DEOBA)3(4,4'-DM-2,2'-bipy)]2·2C_(2)H_(5)OH,[Ln=Dy(1),Eu(2),Tb(3),Sm(4),Ho(5),Gd(6);3,4-DEOBA-=3,4-diethoxybenzoate,4,4'-DM-2,2'-bipy=4,4'-dimethyl-2,2'-bipyridine]were successfully synthesized by the volatilization of the solution at room temperature.The crystal structures of six complexes were determined by single-crystal X-ray diffraction technology.The results showed that the complexes all have a binuclear structure,and the structures contain free ethanol molecules.Moreover,the coordination number of the central metal of each structural unit is eight.Adjacent structural units interact with each other through hydrogen bonds and further expand to form 1D chain-like and 2D planar structures.After conducting a systematic study on the luminescence properties of complexes 1-4,their emission and excitation spectra were obtained.Experimental results indicated that the fluorescence lifetimes of complexes 2 and 3 were 0.807 and 0.845 ms,respectively.The emission spectral data of complexes 1-4 were imported into the CIE chromaticity coordinate system,and their corre sponding luminescent regions cover the yellow light,red light,green light,and orange-red light bands,respectively.Within the temperature range of 299.15-1300 K,the thermal decomposition processes of the six complexes were comprehensively analyzed by using TG-DSC/FTIR/MS technology.The hypothesis of the gradual loss of ligand groups during the decomposition process was verified by detecting the escaped gas,3D infrared spectroscopy,and ion fragment information detected by mass spectrometry.The specific decomposition path is as follows:firstly,free ethanol molecules and neutral ligands are removed,and finally,acidic ligands are released;the final product is the corresponding metal oxide.CCDC:2430420,1;2430422,2;2430419,3;2430424,4;2430421,5;2430423,6.
文摘The present work provides a facile and efficient method for producing ultrafine copper powders.Ultrafine copper powders were synthesized through a solvothermal method,utilizing ethanol both as a solvent and a reducing agent.Specifically,by exploiting the weak reducing property of ethanol,the copper precursor is first converted to copper oxide and then further reduced to cuprous oxide and pure copper.Such a method can effectively control the morphology and particle size of the copper powder,reduce particle aggregation,and enhance oxidation resistance.It is cost-effective and produces fewer toxic by-products.Spherical copper particles with an average particle size of about 180 nm were obtained.The initial oxidation temperature is approximately 150℃,and the resulting copper powders can be stored stably under ambient conditions for at least 5 months,demonstrating excellent oxidation resistance and thermal stability.
基金Guangdong Basic and Applied Basic Research Foundation (2024A1515011873)Shenzhen Basic Research Project (JCYJ20241202123504007)Shenzhen Science and Technology Innovation Commission (KJZD20240903101400001, KJZD20240903102006009)。
文摘A multi-physics approach was used to quantify the effect of process parameters (laser power, scanning speed, hatch spacing, and scanning strategy) on the thermal history and corresponding microstructure evolution of Ti-25Nb (at%) alloy during the dual-track selective laser melting (SLM) process. Simulation results reveal that during the dual-track SLM process, increasing laser power results in greater thermal accumulation, leading to a molten pool of larger volume and coarser grains. Reducing scanning speed enhances remelting and promotes cellular growth at the top of molten pool, whereas faster scanning speed leads to rougher melt tracks and finer grains. Notably, hatch spacing significantly influences the molten pool dimensions and microstructures, and smaller hatch spacing promotes remelting. Furthermore, the orientations of grains in the second track during zigzag scanning differ markedly from those in the first track. More importantly, compared with those after the first track, both the temperature gradient and cooling rate at the boundaries of remelting molten pool are reduced after the second track scanning, resulting in slower interface velocity and significant change in solidification microstructure. This research provides a theoretical foundation for controlling non-equilibrium microstructure and offering novel insights into the optimization of SLM process parameters of titanium alloys.
