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
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.
