It is highly desirable to design and synthesize two-dimensional nanostructured electrode materials with high electrical conductivity,large electrolyte-accessible surface area and more exposed active sites for energy s...It is highly desirable to design and synthesize two-dimensional nanostructured electrode materials with high electrical conductivity,large electrolyte-accessible surface area and more exposed active sites for energy storage applications.Herein,MXene/Co Al-LDH heterostructure has been prepared through electrostatic ordered hetero-assembly of monolayer MXene and edge-rich Co Al-LDH nanosheets in a faceto-face manner on molecular-scale for supercapacitor applications.Benefiting from the unique structure,strong interfacial interaction and synergistic effects between MXene and Co Al-LDH nanosheets,the electrical conductivity and exposed electrolyte-accessible active sites are significantly enhanced.The asprepared MXene/Co Al-LDH-80%(ML-80)film exhibits high volumetric capacity of 2472 C cm-3 in 3 M KOH electrolyte with high rate capability of 70.6%at 20 A g-1.Notably,to the best of our knowledge,the high volumetric capacity is the highest among other previously reported values for supercapacitors in aqueous electrolytes.Furthermore,our asymmetric supercapacitor device fabricated with ML-80 and MXene/graphene composite as cathode and anode,respectively,exhibits impressive volumetric energy density of 85.4 Wh L-1 with impressive cycling stability of 94.4%retention ratio after 30,000 continuous charge/discharge cycles.展开更多
Morphologies of the porous materials influence the processes of solar radiation transport, flow, and thermal behaviors within volumetric solar receivers. A comprehensive comparative study is conducted by applying pore...Morphologies of the porous materials influence the processes of solar radiation transport, flow, and thermal behaviors within volumetric solar receivers. A comprehensive comparative study is conducted by applying pore scale numerical simulations on volumetric solar receivers featuring various morphologies, including Kelvin, Weaire-Phelan, and foam configurations. The idealized unit cell and X-ray computed tomography scan approaches are employed to reconstruct pore scale porous models.Monte Carlo ray tracing and pore scale numerical simulations are implemented to elucidate the radiative, flow, and thermal behaviors of distinct receivers exposed to varying thermal boundary conditions and real irradiation situations. The findings demonstrate that the foam structure exhibits greater solar radiation absorptivity, while Kelvin and Weaire-Phelan structures enhance the penetration depth under non-perpendicular solar irradiation. In comparison with Kelvin and Weaire-Phelan configurations, the foam structure presents efficient convective heat transfer, with the Weaire-Phelan structure showing pronounced thermal non-equilibrium phenomena. The variance in convective heat transfer coefficient between Kelvin and Weaire-Phelan configurations is approximately 8.4%. The foam structure exhibits higher thermal efficiency and flow resistance under nonperpendicular irradiation compared to Kelvin and Weaire-Phelan structures, attributed to its smaller pore size and intricate flow channels. An increase of 1.3% in thermal efficiency is observed with a substantial rise in pressure drop of 32.2%.展开更多
Screw conveyors are widely used for bulk material transportation.This study investigates the critical role of radial clearance,the gap between the screw and the conveyor body,on performance across various inclination ...Screw conveyors are widely used for bulk material transportation.This study investigates the critical role of radial clearance,the gap between the screw and the conveyor body,on performance across various inclination angles.The Discrete Element Method(DEM)is employed to analyze the effects of different radial clearances on conveyor performance for concrete aggregate and sand as bulk materials.Volumetric efficiencies and capacity losses serve as key performance indicators,quantitatively assessed for each radial clearance and inclination combination.Experimental validation is conducted to corroborate the findings.In the study,the optimal radial clearance was identified as 1.5 to 3 times of the particle size.This optimal clearance minimizes the material jamming and increases the performance for screw conveyors with different inclinations and bulk material types as a result.展开更多
Direct pore-scale and volume-averaging numerical simulations are two methods for investigating the performance of porous volumetric solar receivers.To clarify the difference in the prediction of heat transfer processe...Direct pore-scale and volume-averaging numerical simulations are two methods for investigating the performance of porous volumetric solar receivers.To clarify the difference in the prediction of heat transfer processes,a direct comparison between these two methods was conducted at both steady state and transient state.The numerical models were established based on X-ray computed tomography scans and a local thermal non-equilibrium model,respectively.The empirical parameters,which are indispensable to the volume-averaging simulation,were determined by Monte Carlo ray tracing and direct pore-scale numerical simulations.The predicted outlet air temperature of the receiver by the volume-averaging simulation method corresponded satisfactorily to that in the direct pore-scale simulation.The largest discrepancies were observed when the receiver's working temperature was elevated,with differences of 5.5%and 3.68%for the steady state and transient state simulations,respectively.However,the volume-averaging method is incapable of capturing the local temperature information of the air and porous skeleton.It underestimates the inlet temperature of the receiver,leading to an overestimation of the receiver's thermal efficiency,with the largest difference being 6.51%.The comparison results show that the volume-averaging model is a good approximation to the pore-scale model when the empirical parameters are carefully selected.展开更多
High-tap density electrode materials are greatly desired for Li-ion batteries with high volumetric capacities to fulfill the growing demands of electric vehicles and portable smart devices. TiOz, which is one of the m...High-tap density electrode materials are greatly desired for Li-ion batteries with high volumetric capacities to fulfill the growing demands of electric vehicles and portable smart devices. TiOz, which is one of the most attractive an- ode materials, is limited in their application for Li-ion batteries because of its low tap density （usually 〈1 gcm-3） and volumetric capacity. Herein, we report uniform mesoporous TiO2 submicrospheres with a tap density as high as 1.62 gcm-3 as a promising anode material. Even with a high mass load- ing of 24 mg cm-2, the TiO2 submicrospheres have impressive volumetric capacities that are more than double those of their counterparts. Moreover, they can be synthesized with -100% yield and within a reaction time of -6 h by optimizing the experimental conditions and formation mechanism, exhibiting potential for large-scale production for industrial applications. Other mesoporous anode materials, i.e., hightap density mesoporous Li4Ti5O12 submicrospheres, are fabricated using the generalized method. We believe that our work provides a significant reference for the industrial production of mesoporous materials for Li-ion batteries with a high volumetric performance.展开更多
基金supported by the financial support from the National Natural Science Foundation of China(21571040)the Young Top-Notch Talent of National Ten Thousand Talent Program+1 种基金Heilongjiang Touyan Innovation Team ProgramFundamental Research Funds for the Central Universities。
文摘It is highly desirable to design and synthesize two-dimensional nanostructured electrode materials with high electrical conductivity,large electrolyte-accessible surface area and more exposed active sites for energy storage applications.Herein,MXene/Co Al-LDH heterostructure has been prepared through electrostatic ordered hetero-assembly of monolayer MXene and edge-rich Co Al-LDH nanosheets in a faceto-face manner on molecular-scale for supercapacitor applications.Benefiting from the unique structure,strong interfacial interaction and synergistic effects between MXene and Co Al-LDH nanosheets,the electrical conductivity and exposed electrolyte-accessible active sites are significantly enhanced.The asprepared MXene/Co Al-LDH-80%(ML-80)film exhibits high volumetric capacity of 2472 C cm-3 in 3 M KOH electrolyte with high rate capability of 70.6%at 20 A g-1.Notably,to the best of our knowledge,the high volumetric capacity is the highest among other previously reported values for supercapacitors in aqueous electrolytes.Furthermore,our asymmetric supercapacitor device fabricated with ML-80 and MXene/graphene composite as cathode and anode,respectively,exhibits impressive volumetric energy density of 85.4 Wh L-1 with impressive cycling stability of 94.4%retention ratio after 30,000 continuous charge/discharge cycles.
基金supported by the National Natural Science Foundation of China(Grant Nos.52341601 and 52306272)the Postdoctoral Research Project Funding in Shaanxi Province(Grant No.2023BSHYDZZ40)。
文摘Morphologies of the porous materials influence the processes of solar radiation transport, flow, and thermal behaviors within volumetric solar receivers. A comprehensive comparative study is conducted by applying pore scale numerical simulations on volumetric solar receivers featuring various morphologies, including Kelvin, Weaire-Phelan, and foam configurations. The idealized unit cell and X-ray computed tomography scan approaches are employed to reconstruct pore scale porous models.Monte Carlo ray tracing and pore scale numerical simulations are implemented to elucidate the radiative, flow, and thermal behaviors of distinct receivers exposed to varying thermal boundary conditions and real irradiation situations. The findings demonstrate that the foam structure exhibits greater solar radiation absorptivity, while Kelvin and Weaire-Phelan structures enhance the penetration depth under non-perpendicular solar irradiation. In comparison with Kelvin and Weaire-Phelan configurations, the foam structure presents efficient convective heat transfer, with the Weaire-Phelan structure showing pronounced thermal non-equilibrium phenomena. The variance in convective heat transfer coefficient between Kelvin and Weaire-Phelan configurations is approximately 8.4%. The foam structure exhibits higher thermal efficiency and flow resistance under nonperpendicular irradiation compared to Kelvin and Weaire-Phelan structures, attributed to its smaller pore size and intricate flow channels. An increase of 1.3% in thermal efficiency is observed with a substantial rise in pressure drop of 32.2%.
文摘Screw conveyors are widely used for bulk material transportation.This study investigates the critical role of radial clearance,the gap between the screw and the conveyor body,on performance across various inclination angles.The Discrete Element Method(DEM)is employed to analyze the effects of different radial clearances on conveyor performance for concrete aggregate and sand as bulk materials.Volumetric efficiencies and capacity losses serve as key performance indicators,quantitatively assessed for each radial clearance and inclination combination.Experimental validation is conducted to corroborate the findings.In the study,the optimal radial clearance was identified as 1.5 to 3 times of the particle size.This optimal clearance minimizes the material jamming and increases the performance for screw conveyors with different inclinations and bulk material types as a result.
基金supported by the National Natural Science Foundation of China(No.52306272 and No.52293413)the Postdoctoral Research Project Funding in Shaanxi Province(No.2023BSHYDZZ40)。
文摘Direct pore-scale and volume-averaging numerical simulations are two methods for investigating the performance of porous volumetric solar receivers.To clarify the difference in the prediction of heat transfer processes,a direct comparison between these two methods was conducted at both steady state and transient state.The numerical models were established based on X-ray computed tomography scans and a local thermal non-equilibrium model,respectively.The empirical parameters,which are indispensable to the volume-averaging simulation,were determined by Monte Carlo ray tracing and direct pore-scale numerical simulations.The predicted outlet air temperature of the receiver by the volume-averaging simulation method corresponded satisfactorily to that in the direct pore-scale simulation.The largest discrepancies were observed when the receiver's working temperature was elevated,with differences of 5.5%and 3.68%for the steady state and transient state simulations,respectively.However,the volume-averaging method is incapable of capturing the local temperature information of the air and porous skeleton.It underestimates the inlet temperature of the receiver,leading to an overestimation of the receiver's thermal efficiency,with the largest difference being 6.51%.The comparison results show that the volume-averaging model is a good approximation to the pore-scale model when the empirical parameters are carefully selected.
基金supported by the National High Technology Research and Development Program of China (2013AA050901)the National Basic Research Program of China (2015CB251100)+2 种基金the Thousand Youth Talents Programthe National Natural Science Foundation of China(51602173,51371015 and 11674023)China Postdoctoral Science Foundation(2016M591186)
文摘High-tap density electrode materials are greatly desired for Li-ion batteries with high volumetric capacities to fulfill the growing demands of electric vehicles and portable smart devices. TiOz, which is one of the most attractive an- ode materials, is limited in their application for Li-ion batteries because of its low tap density （usually 〈1 gcm-3） and volumetric capacity. Herein, we report uniform mesoporous TiO2 submicrospheres with a tap density as high as 1.62 gcm-3 as a promising anode material. Even with a high mass load- ing of 24 mg cm-2, the TiO2 submicrospheres have impressive volumetric capacities that are more than double those of their counterparts. Moreover, they can be synthesized with -100% yield and within a reaction time of -6 h by optimizing the experimental conditions and formation mechanism, exhibiting potential for large-scale production for industrial applications. Other mesoporous anode materials, i.e., hightap density mesoporous Li4Ti5O12 submicrospheres, are fabricated using the generalized method. We believe that our work provides a significant reference for the industrial production of mesoporous materials for Li-ion batteries with a high volumetric performance.
