Electrochemical impedance spectroscopy(EIS)is a robust characterization method to probe prevalent(electro)chemical processes in an electrochemical system.Despite its extensive utilization in fuel cell research,the app...Electrochemical impedance spectroscopy(EIS)is a robust characterization method to probe prevalent(electro)chemical processes in an electrochemical system.Despite its extensive utilization in fuel cell research,the application of EIS in redox flow battery systems particularly for simplified two-electrode full-cell configurations is more limited.Herein we attempt to strengthen the understa nding of cha racteristic EIS data of vanadium redox flow batteries by a combination of equivalent circuit modeling with a validated Multiphysics model analyzed under hydrodynamic conditions in frequency domain.Following a highlight of system linearity and stability concerns for EIS in redox flow batteries,we specifically use our combinatory approach to investigate the effects of different cell component properties on observed galva nostatic EIS spectra and accompanying fitted equivalent circuit element parameters.For the investigated two-electrode full-cell flow battery configuration with the same electrode material on both sides,the EIS spectral data is observed to be dominated by different mass or cha rge transport processes at different ends of the spectrum.Sensitivity analyses of both obtained EIS spectral data and fitted circuit elements parameters show that electrode morphological properties,membrane porosity,and electrolyte inflow conditions predominantly define the EIS spectral data.Insights from the type of analyses performed herein can facilitate flow battery cell/stack diagnostics and targeted performance improvement efforts.展开更多
In this paper,we propose a multiphysics finite element method for a nonlinear poroelasticity model with nonlinear stress-strain relation.Firstly,we reformulate the original problem into a new coupled fluid system-a ge...In this paper,we propose a multiphysics finite element method for a nonlinear poroelasticity model with nonlinear stress-strain relation.Firstly,we reformulate the original problem into a new coupled fluid system-a generalized nonlinear Stokes problem of displacement vector field related to pseudo pressure and a diffusion problem of other pseudo pressure fields.Secondly,a fully discrete multiphysics finite element method is performed to solve the reformulated system numerically.Thirdly,existence and uniqueness of the weak solution of the reformulated model and stability analysis and optimal convergence order for the multiphysics finite element method are proven theoretically.Lastly,numerical tests are given to verify the theoretical results.展开更多
In this paper,we design a new error estimator and give a posteriori error analysis for a poroelasticity model.To better overcome“locking phenomenon”on pressure and displacement,we proposed a new error estimators bas...In this paper,we design a new error estimator and give a posteriori error analysis for a poroelasticity model.To better overcome“locking phenomenon”on pressure and displacement,we proposed a new error estimators based on multiphysics discontinuous Galerkin method for the poroelasticity model.And we prove the upper and lower bound of the proposed error estimators,which are numerically demonstrated to be computationally very efficient.Finally,we present numerical examples to verify and validate the efficiency of the proposed error estimators,which show that the adaptive scheme can overcome“locking phenomenon”and greatly reduce the computation cost.展开更多
Underground liquified natural gas(LNG)storage is essential in guaranteeing national energy strategic reserves,and its construction is being accelerated.The stability of surrounding rock of underground LNG storage cave...Underground liquified natural gas(LNG)storage is essential in guaranteeing national energy strategic reserves,and its construction is being accelerated.The stability of surrounding rock of underground LNG storage caverns under stress-low temperature coupling effect is the key factor determining the feasibility of LNG storage.First,a mathematical model used for controlling the stress-low temperature coupling and the processes of rock damage evolution is given,followed by a 2-D numerical execution process of the mathematical model mentioned above described based on Comsol Multiphysics and Matlab code.Finally,a series of 2-D simulations are performed to study the influence of LNG storage cavern layout,burial depth,temperature and internal pressure on the stability of surrounding rocks of these underground storage caverns.The results indicate that all the factors mentioned above affect the evolution of deformation and plastic zone of surrounding rocks.The research results contribute to the engineering design of underground LNG storage caverns.展开更多
Silicon monoxide(SiO)(silicon[Si]mixed with silicon dioxide[SiO_(2)])/graphite(Gr)composite material is one of the most commercially promising anode materials for the next generation of high-energy-density lithium-ion...Silicon monoxide(SiO)(silicon[Si]mixed with silicon dioxide[SiO_(2)])/graphite(Gr)composite material is one of the most commercially promising anode materials for the next generation of high-energy-density lithium-ion batteries.The major bottleneck for SiO/Gr composite anode is the poor cyclability arising from the stress/strain behaviors due to the mismatch between two heterogenous materials during the lithiation/delithiation process.To date,a meticulous and quantitative understanding of the highly nonlinear coupling behaviors of such materials is still lacking.Herein,an electro–chemo–mechanics-coupled detailed model containing particle geometries is established.The underlying mechanism of the regulation between SiO and Gr components during electrochemical cycling is quantitatively revealed.We discover that increasing the SiO weight percentage(wt%)reduces the utilization efficiency of the active materials at the same 1C rate charging and enhances the hindering effects of stress-driven flux on diffusion.In addition,the mechanical constraint demonstrates a balanced effect on the overall performance of cells and the local behaviors of particles.This study provides new insights into the fundamental interactions between SiO and Gr materials and advances the investigation methodology for the design and evaluation of next-generation high-energydensity batteries.展开更多
Thermal-electric bilayer invisibility cloak can prevent the heat flux and electric current from touching the object without distorting the external temperature and electric potential fields simultaneously.In this pape...Thermal-electric bilayer invisibility cloak can prevent the heat flux and electric current from touching the object without distorting the external temperature and electric potential fields simultaneously.In this paper,we design an omnidirectional thermal-electric invisibility cloak with anisotropic geometry.Based on the theory of neutral inclusion,the anisotropic effective thermal and electric conductivities of confocal elliptical bilayer core-shell structure are derived,thus obtaining the anisotropic matrix material to eliminate the external disturbances omnidirectionally.The inner shell of the cloak is selected as an insulating material to shield the heat flux and electric current.Then,the omnidirectional thermal-electric cloaking effect is verified numerically and experimentally based on the theoretical anisotropic matrix and manufactured composite structure,respectively.Furthermore,we achieve the thermal-electric cloaking effect under a specific direction of heat flux and electric current using the isotropic natural materials to broaden the selection range of materials.The method proposed to eliminate anisotropy and achieve the omnidirectional effect could also be expanded to other different physical fields for the metadevices with different functions.展开更多
Upgrades to power systems and the rapid growth of electric vehicles significantly heighten the importance of lithium-ion batteries(LiBs)in energy systems.As a complex dynamic system;the charging and discharging process...Upgrades to power systems and the rapid growth of electric vehicles significantly heighten the importance of lithium-ion batteries(LiBs)in energy systems.As a complex dynamic system;the charging and discharging process of LiBs involves the evolution of multiphysicsfields;such as concentration;electricity;and stress.For quantitative analysis of the internal mechanisms of LiBs;as well as the development guidance and performance prediction of high-performance batteries;modeling has advantages that cannot be matched by traditional experimental methods.Major research efforts in the past decades have made significant strides in modeling the internal processes and physicalfield evolution of LiBs.Importantly;the scattered ideas need to be integrated into a structured framework to form a complete LiBs multi-physicalfield model.This work reviews important ad-vances in LiBs modeling from the perspectives of describing the internal processes of the battery and portraying the evolution of the physicalfield.First;quantitative descriptions of the charging and discharging behaviors and the side reactions are reviewed to investigate the battery reaction mechanisms.In addition;the characterization of the evolution of the stress and temperaturefields within the battery as well as the coupling between them and the internal reactions are discussed.Finally;some suggestions for future improvements in the modeling are given;ranging from equation optimization to parameter acquisition and the application of artificial intelligence.It is hoped that this work will facilitate the development of models with sufficient accuracy and efficient computa-tional cost to provide guidance for the improvement of LiBs.展开更多
Additive manufacturing of fiber-reinforced polymer composites has garnered great interest due to its potential in fabricating functional products with lightweight characteristics and unique material properties.However...Additive manufacturing of fiber-reinforced polymer composites has garnered great interest due to its potential in fabricating functional products with lightweight characteristics and unique material properties.However,the major concern in polymer composites remains the presence of pore defects,as a thorough understanding of pore formation is insufficient.In this study,a powder-scale multiphysics framework has been developed to simulate the printing process of fiber-reinforced polymer composites in powder bed fusion additive manufacturing.This numerical framework involves various multiphysics phenomena such as particle flow dynamics of fiber-reinforced polymer composite powder,infrared laser–particle interaction,heat transfer,and multiphase fluid flow dynamics.The melt depths of one-layer glass fiber–reinforced polyamide 12 composite parts fabricated by selective laser sintering are measured to validate modelling predictions.The numerical framework is employed to conduct an in-depth investigation of pore formation mechanisms within printed composites.Our simulation results suggest that an increasing fiber weight fraction would lead to a lower densification rate,larger porosity,and lower pore sphericity in the composites.展开更多
基金sponsored by the Dubai Electricity and Water Authority(DEWA)R&D centre,Dubai,United Arab Emirates。
文摘Electrochemical impedance spectroscopy(EIS)is a robust characterization method to probe prevalent(electro)chemical processes in an electrochemical system.Despite its extensive utilization in fuel cell research,the application of EIS in redox flow battery systems particularly for simplified two-electrode full-cell configurations is more limited.Herein we attempt to strengthen the understa nding of cha racteristic EIS data of vanadium redox flow batteries by a combination of equivalent circuit modeling with a validated Multiphysics model analyzed under hydrodynamic conditions in frequency domain.Following a highlight of system linearity and stability concerns for EIS in redox flow batteries,we specifically use our combinatory approach to investigate the effects of different cell component properties on observed galva nostatic EIS spectra and accompanying fitted equivalent circuit element parameters.For the investigated two-electrode full-cell flow battery configuration with the same electrode material on both sides,the EIS spectral data is observed to be dominated by different mass or cha rge transport processes at different ends of the spectrum.Sensitivity analyses of both obtained EIS spectral data and fitted circuit elements parameters show that electrode morphological properties,membrane porosity,and electrolyte inflow conditions predominantly define the EIS spectral data.Insights from the type of analyses performed herein can facilitate flow battery cell/stack diagnostics and targeted performance improvement efforts.
基金Supported by the National Natural Science Foundation of China(Grant Nos.12371393,11971150 and 11801143)Natural Science Foundation of Henan Province(Grant No.242300421047).
文摘In this paper,we propose a multiphysics finite element method for a nonlinear poroelasticity model with nonlinear stress-strain relation.Firstly,we reformulate the original problem into a new coupled fluid system-a generalized nonlinear Stokes problem of displacement vector field related to pseudo pressure and a diffusion problem of other pseudo pressure fields.Secondly,a fully discrete multiphysics finite element method is performed to solve the reformulated system numerically.Thirdly,existence and uniqueness of the weak solution of the reformulated model and stability analysis and optimal convergence order for the multiphysics finite element method are proven theoretically.Lastly,numerical tests are given to verify the theoretical results.
基金supported by the National Natural Science Foundation of China(Grant Nos.12371393 and 11971150)Natural Science Foundation of Henan(Grant No.242300421047).
文摘In this paper,we design a new error estimator and give a posteriori error analysis for a poroelasticity model.To better overcome“locking phenomenon”on pressure and displacement,we proposed a new error estimators based on multiphysics discontinuous Galerkin method for the poroelasticity model.And we prove the upper and lower bound of the proposed error estimators,which are numerically demonstrated to be computationally very efficient.Finally,we present numerical examples to verify and validate the efficiency of the proposed error estimators,which show that the adaptive scheme can overcome“locking phenomenon”and greatly reduce the computation cost.
基金funded by the Major science and technology project of CNOOC(KJZX-2022-12-XNY-0803).
文摘Underground liquified natural gas(LNG)storage is essential in guaranteeing national energy strategic reserves,and its construction is being accelerated.The stability of surrounding rock of underground LNG storage caverns under stress-low temperature coupling effect is the key factor determining the feasibility of LNG storage.First,a mathematical model used for controlling the stress-low temperature coupling and the processes of rock damage evolution is given,followed by a 2-D numerical execution process of the mathematical model mentioned above described based on Comsol Multiphysics and Matlab code.Finally,a series of 2-D simulations are performed to study the influence of LNG storage cavern layout,burial depth,temperature and internal pressure on the stability of surrounding rocks of these underground storage caverns.The results indicate that all the factors mentioned above affect the evolution of deformation and plastic zone of surrounding rocks.The research results contribute to the engineering design of underground LNG storage caverns.
文摘Silicon monoxide(SiO)(silicon[Si]mixed with silicon dioxide[SiO_(2)])/graphite(Gr)composite material is one of the most commercially promising anode materials for the next generation of high-energy-density lithium-ion batteries.The major bottleneck for SiO/Gr composite anode is the poor cyclability arising from the stress/strain behaviors due to the mismatch between two heterogenous materials during the lithiation/delithiation process.To date,a meticulous and quantitative understanding of the highly nonlinear coupling behaviors of such materials is still lacking.Herein,an electro–chemo–mechanics-coupled detailed model containing particle geometries is established.The underlying mechanism of the regulation between SiO and Gr components during electrochemical cycling is quantitatively revealed.We discover that increasing the SiO weight percentage(wt%)reduces the utilization efficiency of the active materials at the same 1C rate charging and enhances the hindering effects of stress-driven flux on diffusion.In addition,the mechanical constraint demonstrates a balanced effect on the overall performance of cells and the local behaviors of particles.This study provides new insights into the fundamental interactions between SiO and Gr materials and advances the investigation methodology for the design and evaluation of next-generation high-energydensity batteries.
基金This work was financially supported by the National Natural Science Foundation of China(Grant No.11572090)the Fundamental Research Funds for the Central Universities(Grant No.3072022GIP0202).
文摘Thermal-electric bilayer invisibility cloak can prevent the heat flux and electric current from touching the object without distorting the external temperature and electric potential fields simultaneously.In this paper,we design an omnidirectional thermal-electric invisibility cloak with anisotropic geometry.Based on the theory of neutral inclusion,the anisotropic effective thermal and electric conductivities of confocal elliptical bilayer core-shell structure are derived,thus obtaining the anisotropic matrix material to eliminate the external disturbances omnidirectionally.The inner shell of the cloak is selected as an insulating material to shield the heat flux and electric current.Then,the omnidirectional thermal-electric cloaking effect is verified numerically and experimentally based on the theoretical anisotropic matrix and manufactured composite structure,respectively.Furthermore,we achieve the thermal-electric cloaking effect under a specific direction of heat flux and electric current using the isotropic natural materials to broaden the selection range of materials.The method proposed to eliminate anisotropy and achieve the omnidirectional effect could also be expanded to other different physical fields for the metadevices with different functions.
基金funding support from National Key R&D Program of China(2023YFB2408100)Chinese Academy of Sciences Project for Young Scientists in Basic Research(YSBR-098)National Innovative Talents Program(GG2090007001).
文摘Upgrades to power systems and the rapid growth of electric vehicles significantly heighten the importance of lithium-ion batteries(LiBs)in energy systems.As a complex dynamic system;the charging and discharging process of LiBs involves the evolution of multiphysicsfields;such as concentration;electricity;and stress.For quantitative analysis of the internal mechanisms of LiBs;as well as the development guidance and performance prediction of high-performance batteries;modeling has advantages that cannot be matched by traditional experimental methods.Major research efforts in the past decades have made significant strides in modeling the internal processes and physicalfield evolution of LiBs.Importantly;the scattered ideas need to be integrated into a structured framework to form a complete LiBs multi-physicalfield model.This work reviews important ad-vances in LiBs modeling from the perspectives of describing the internal processes of the battery and portraying the evolution of the physicalfield.First;quantitative descriptions of the charging and discharging behaviors and the side reactions are reviewed to investigate the battery reaction mechanisms.In addition;the characterization of the evolution of the stress and temperaturefields within the battery as well as the coupling between them and the internal reactions are discussed.Finally;some suggestions for future improvements in the modeling are given;ranging from equation optimization to parameter acquisition and the application of artificial intelligence.It is hoped that this work will facilitate the development of models with sufficient accuracy and efficient computa-tional cost to provide guidance for the improvement of LiBs.
基金supported by the RIE2020 Industry Alignment Fund–Industry Collaboration Projects(IAF–ICP)Funding Initiative,Singapore and cash and in-kind contribution from the industry partner,HP Inc.
文摘Additive manufacturing of fiber-reinforced polymer composites has garnered great interest due to its potential in fabricating functional products with lightweight characteristics and unique material properties.However,the major concern in polymer composites remains the presence of pore defects,as a thorough understanding of pore formation is insufficient.In this study,a powder-scale multiphysics framework has been developed to simulate the printing process of fiber-reinforced polymer composites in powder bed fusion additive manufacturing.This numerical framework involves various multiphysics phenomena such as particle flow dynamics of fiber-reinforced polymer composite powder,infrared laser–particle interaction,heat transfer,and multiphase fluid flow dynamics.The melt depths of one-layer glass fiber–reinforced polyamide 12 composite parts fabricated by selective laser sintering are measured to validate modelling predictions.The numerical framework is employed to conduct an in-depth investigation of pore formation mechanisms within printed composites.Our simulation results suggest that an increasing fiber weight fraction would lead to a lower densification rate,larger porosity,and lower pore sphericity in the composites.
