Fluid Topology Optimization Of Complex Porous Copper Fiber Sintered Felt

Methanol steam reforming(MSR)is one of the important development directions in the field of hydrogen production,and the catalyst support of MSR microreactor is the key to the performance of hydrogen production.Among many catalyst supports,Porous Copper Fiber Sintered Felt(PCFSF)has great potential for research due to its high porosity and high hydrogen selectivity.The introduction of gradient porosity has further enhanced the design freedom and hydrogen production performance of PCFSF.However,the current design and optimization methods of gradient porosity PCFSF still lack a clear basis.It is shown that the uniformity of the flow field is closely related to the structure of the catalyst support,and when the structure of the catalyst carrier changes,the flow velocity distribution of the carrier will change accordingly,which will affect the mass transfer performance of the catalyst support,thus affecting the hydrogen production performance.Therefore,the structure of the catalyst supportcan be optimized by taking the enhancement of the flow velocity field uniformity as the optimization objective.Fluid topology optimization method are often used to enhance the performance while obtaining novel topological designs.In this paper,we apply them to PCFSF in order to obtain the optimal topology under the optimization objective and to provide a more effective and reasonable method for the structural design of gradient porosity PCFSF.To this end,this paper proposes a topology optimization method applicable to PCFSF by constructing a two-dimensional numerical simulation model of PCFSF with the objective of improving the flow field uniformity,guiding the design of PCFSF gradient porosity structure,and geometrically reconstructing the topology optimization results on the basis of considering manufacturability.The main research contents are as follows.(1)A two-dimensional numerical analysis model of PCFSF is established.According to the actual dimensions of the reforming chamber of the MSR microreactor,the parameters of the two-dimensional geometric model of PCFSF are determined;the macroscopic description of the fluid flow of PCFSF is realized according to the continuity equation,the momentum conservation equation,and Darcy’s law;the appropriate number of mesh divisions is determined according to the mesh independence analysis method;the flow field of PCFSF with uniform or gradient porosity is obtained by giving different inlet velocity information;finally,the numerical simulation results are compared with the pre-simulation data to verify the accuracy of the numerical analysis model.(2)A topology optimization model of PCFSF with the flow velocity field uniformity as the optimization objective is established.Combining the basic principles of continuum topology optimization method and variable density method,the topology optimization design variables of PCFSF are determined;according to the fluid flow state,the control equations and constraints of each calculation domain are determined;according to the porosity and permeability of PCFSF,the parameters of Darcy interpolation function are determined by the curve fitting method;the evaluation index of flow field uniformity of PCFSF is constructed,and it as the optimization target;finally,the topological optimization model of PCFSF is integrated and proposed,and the description of the topological optimization problem of PCFSF is realized.(3)The numerical solution of the topology optimization of PCFSF is implemented.Given the iterative process of topology optimization of PCFSF,the principles related to the adjoint method-based sensitivity analysis and the Method of Moving Asymptotes(MMA)-based design variable update are introduced;the topology optimization results are very similar after the iterative convergence with different initial values of design variables,and the flow field uniformity is effectively improved.The topology optimized design results include the magnitude of porosity taken for all mesh nodes after PCFSF discretization,which provides a design basis for the subsequent topological reconfiguration of PCFSF considering manufacturability.(4)A topology reconstruction method based on K-Means clustering analysis and mean filtering is proposed considering manufacturability.According to the preparation process of PCFSF,the topology optimization region is reconstructed by K-Means cluster analysis method,and the number of topology region classification and the initial shape of the interface of PCFSF are determined;the topology region interface is smoothed by using mean filtering method,and the smoothed PCFSF structure design is obtained;the flow field of different types of PCFSF is analyzed by finite element simulation method,and the integrated flow velocity field uniformity is determined.Analysis of the flow field uniformity and the variation of the pressure drop performance are integrated to find the manufacturable PCFSF design with optimal performance.