Protonic ceramic fuel cells(PCFCs)have been attracting increasing attention because of their advances in high-efficiency power generation in an intermediate-temperature range,as compared to the high-temperature solid ...Protonic ceramic fuel cells(PCFCs)have been attracting increasing attention because of their advances in high-efficiency power generation in an intermediate-temperature range,as compared to the high-temperature solid oxide fuel cells(SOFCs).The greatest difference between PCFCs and SOFCs is the specific requirement of protonic(H+)conductivity at the PCFC cathode,in addition to the electronic(e^(-))and oxide-ion(O^(2-))conductivity.The development of a triple H^(+)/e^(-)/O^(2-)conductor for PCFC cathode is still challenging.Thus,the most-widely used cathode material is based on the mature e^(-)/O^(2-)conductor.However,this leads to insufficient triple phase boundary(TPB),i.e.,reaction area.Herein,an efficient strategy that uses a~100 nm-thick proton conductive functional layer(La_(0.5)Sr_(0.5)CoO_(3-δ),LSC55)in-between the typical La_(0.8)Sr_(0.2)CoO_(3-δ)cathode(a mature e-/O^(2-)conductor,LS C 82)and B aZr_(0.4)Ce_(0.4)Y_(0.1)Yb_(0.)1O_(3-δ)elec trolyte(11 mm in diameter,20μm in thickness)is proposed to significantly enhance the reaction area.Reasonably,the ohmic resistance and polarization resistance are both decreased by 47%and 62%,respectively,compared with that of PCFCs without the functional layer.The power density of the PCFC with such a functional layer can be raised by up to 2.24 times,superior to those described in previous reports.The enhanced PCFC performances are attributed to the well-built TPB and enhanced reaction area via the functional layer engineering strategy.展开更多
In this study, two studies are performed. One is to apply paraxial boundary conditions which are local boundary conditions based on paraxial approximations of the one-way wave equations to finite element analysis. To ...In this study, two studies are performed. One is to apply paraxial boundary conditions which are local boundary conditions based on paraxial approximations of the one-way wave equations to finite element analysis. To do this, a penalty functional is proposed and the existence and uniqueness of the extremum of the proposed functional is demonstrated. The other is to improve the capacity of viscous boundary conditions using dashpots. To do this, customary viscous boundary conditions are modified to maximize the efficiency according to angles of incidence and materials. For the numerical analysis of elasticity with paraxial boundary conditions and the modified viscous boundary conditions, the coding of the finite element models is implemented, and the efficiency of those boundary conditions is investigated.展开更多
According to the necessary condition of the functional taking the extremum, that is its first variation is equal to zero, the variational problems of the functionals for the undetermined boundary in the calculus of va...According to the necessary condition of the functional taking the extremum, that is its first variation is equal to zero, the variational problems of the functionals for the undetermined boundary in the calculus of variations are researched, the functionals depend on single argument, arbitrary unknown functions and their derivatives of higher orders. A new view point is posed and demonstrated, i.e. when the first variation of the functional is equal to zero, all the variational terms are not independent to each other, and at least one of them is equal to zero. Some theorems and corollaries of the variational problems of the functionals are obtained.展开更多
nonrecurrence theorem on the existence of periodic solutions for functional differential equations is proved by employing the topological method, and some applications are given.
Character of contract pressure distribution between the outside surface of the sealing material and rigid cylinder wall depending on geometrical sizes and mechanical properties of a sealer under its unilateral compres...Character of contract pressure distribution between the outside surface of the sealing material and rigid cylinder wall depending on geometrical sizes and mechanical properties of a sealer under its unilateral compression, is defined. The magnitude of the axial load for achieving tightness is determined. The dependence between the magnitude of the axial load necessary for achieving tightness and geometrical sizes is determined. It is shown that with a decrease in the height of the sealing element, the axial load necessary for achieving tightness greatly increases. Threshold height of the sealer, above which contact pressure depends little on the magnitude of the axial load, is defined. The stress-strain state of the sealing element is defined with regard to viscous-elastic properties of its material. It is shown that this greatly influences its sealing ability.展开更多
基金financially supported by China Post-doctoral Science Foundation(No.2022M710856)Guangzhou Postdoctoral Research Project(No.62104380)+2 种基金the Outstanding Youth Project of Natural Science Foundation of Guangdong Province(No.2022B1515020020)the Funding by Science and Technology Projects in Guangzhou(Nos.202206050003 and 202201010603)Guangdong Engineering Technology Research Center for Hydrogen Energy and Fuel Cells。
文摘Protonic ceramic fuel cells(PCFCs)have been attracting increasing attention because of their advances in high-efficiency power generation in an intermediate-temperature range,as compared to the high-temperature solid oxide fuel cells(SOFCs).The greatest difference between PCFCs and SOFCs is the specific requirement of protonic(H+)conductivity at the PCFC cathode,in addition to the electronic(e^(-))and oxide-ion(O^(2-))conductivity.The development of a triple H^(+)/e^(-)/O^(2-)conductor for PCFC cathode is still challenging.Thus,the most-widely used cathode material is based on the mature e^(-)/O^(2-)conductor.However,this leads to insufficient triple phase boundary(TPB),i.e.,reaction area.Herein,an efficient strategy that uses a~100 nm-thick proton conductive functional layer(La_(0.5)Sr_(0.5)CoO_(3-δ),LSC55)in-between the typical La_(0.8)Sr_(0.2)CoO_(3-δ)cathode(a mature e-/O^(2-)conductor,LS C 82)and B aZr_(0.4)Ce_(0.4)Y_(0.1)Yb_(0.)1O_(3-δ)elec trolyte(11 mm in diameter,20μm in thickness)is proposed to significantly enhance the reaction area.Reasonably,the ohmic resistance and polarization resistance are both decreased by 47%and 62%,respectively,compared with that of PCFCs without the functional layer.The power density of the PCFC with such a functional layer can be raised by up to 2.24 times,superior to those described in previous reports.The enhanced PCFC performances are attributed to the well-built TPB and enhanced reaction area via the functional layer engineering strategy.
文摘In this study, two studies are performed. One is to apply paraxial boundary conditions which are local boundary conditions based on paraxial approximations of the one-way wave equations to finite element analysis. To do this, a penalty functional is proposed and the existence and uniqueness of the extremum of the proposed functional is demonstrated. The other is to improve the capacity of viscous boundary conditions using dashpots. To do this, customary viscous boundary conditions are modified to maximize the efficiency according to angles of incidence and materials. For the numerical analysis of elasticity with paraxial boundary conditions and the modified viscous boundary conditions, the coding of the finite element models is implemented, and the efficiency of those boundary conditions is investigated.
文摘According to the necessary condition of the functional taking the extremum, that is its first variation is equal to zero, the variational problems of the functionals for the undetermined boundary in the calculus of variations are researched, the functionals depend on single argument, arbitrary unknown functions and their derivatives of higher orders. A new view point is posed and demonstrated, i.e. when the first variation of the functional is equal to zero, all the variational terms are not independent to each other, and at least one of them is equal to zero. Some theorems and corollaries of the variational problems of the functionals are obtained.
文摘nonrecurrence theorem on the existence of periodic solutions for functional differential equations is proved by employing the topological method, and some applications are given.
文摘Character of contract pressure distribution between the outside surface of the sealing material and rigid cylinder wall depending on geometrical sizes and mechanical properties of a sealer under its unilateral compression, is defined. The magnitude of the axial load for achieving tightness is determined. The dependence between the magnitude of the axial load necessary for achieving tightness and geometrical sizes is determined. It is shown that with a decrease in the height of the sealing element, the axial load necessary for achieving tightness greatly increases. Threshold height of the sealer, above which contact pressure depends little on the magnitude of the axial load, is defined. The stress-strain state of the sealing element is defined with regard to viscous-elastic properties of its material. It is shown that this greatly influences its sealing ability.
