The Optimizing Design On The Gradient Porous Metal Fiber Sintered Felt

With the aggravating unceasingly of the environmental pollution and the rapid depletion of fossil fuels,such as petroleum and natural gas,more and more attention has been paid to the development about new energy which is represented by hydrogen.The methanol reforming reaction in the micro-reactor was seen as one of the most effective means of providing online hydrogen sources for tiny electronic devices such as fuel cells.Stable and highly efficient catalyst support is the key component of micro-reactor for hydrogen production from methanol reforming reaction,while porous copper fiber sintered felt(PCFSF)with its advantages of low manufacturing cost and strong load capacity,in recent years gradually develop into a new kind of catalyst support.However,there are still many challenges in the design and manufacture of porous copper fiber sintered felt with controllable porosity distribution and optimization hydrogen performance.In this thesis,the optimal flow velocity field distribution of porous copper fiber sintered felt is obtained by means of numerical analysis,and the topological structure of the sintered felt is optimized;on this basis,four kinds of new porous copper fiber sintering felt with optimized topological structure are prepared by the method of multi-step molding and solid-phase sintering;finally,hydrogen production from methanol reforming reaction via the above four types of novel porous sintered copper fiber board has carried on the experimental study by an experimental test platform,so as to select the fiber felt with optimal hydrogen capacity,and then analyze the relationship about corresponding topological structure and the performance of the experiment as well as the porosity distribution.The main work of this article includes:(1)The macroscopic numerical simulation of the gradient porous copper fiber sintering felt.To describe the structure of the porous copper fiber sintered felt,the macroscopic model was established by using the ANSYS/FLUENT module(Porous Media)for porous copper fiber sintered felt with the uniform porosity,two gradient porosity and three gradient porosity.Considering the actual condition of methanol reforming reaction,this thesis proposes a macro numerical simulation method to study the above three kinds of structure of porous flow field distribution of the sintered copper fiber board,with the changing porosity distribution of porous sintered copper fiber felt model and entrance velocity.The result shows that,comparing with the single porosity structure,the gradient structure can greatly optimize the flow distribution and make its velocity field become more uniform,and which have great impact on the hydrogen production reaction performance.(2)The manufacture of porous copper fiber sintering felt based on velocity field topology optimization.The cutting process of continuous copper fiber on the horizontal lathe with multi-tooth cutter is used to produce the copper fiber with the equivalent diameter of 100 mm with the intensive micro surface topography.With the single porosity,two gradient porosity and three gradient porosity three types of flow field distribution of the porous sintered copper fiber felt for design guidance,wire-cutting processing methods were used to fabricated the metal block which were consistent with the shape of the flow field.The multi-step molding process is carried out with metal block after filling the copper fiber in the corresponding mould.Using low temperature solid phase sintering technology under the temperature of 900?,the porous sintered copper fiber felt with optimal gradient structure was manufactured according to the fixed heating curve.Based on the design method of topology optimization about the velocity field,the gradient porous copper fiber sintering felt with a new topological structure was prepared.(3)Experimental study on the optimal porosity distribution of the gradient porous copper fiber sintered felt.The Cu-Zn-Al-Zr quaternary system catalyst was applied to the porous copper fiber sintering felt with optimized gradient structure.Ultrasonic water bath vibrator was used to study the strength of the catalyst loading.The methanol conversion rate,hydrogen flow rate and concentration of hydrogen and carbon monoxide selective was obtained about the different structure of fiber felt with the test platform of methanol reforming reaction,and which the reactants solution injection speed and reaction temperature was set to respectively in 6-14ml/h and 260-380? range.The hydrogen production performance of the optimized porous copper fiber sintering felt was compared with that of single porosity,two-gradient porosity and three-gradient porosity.Results show that,under the condition of a certain reaction space velocity and reaction temperature,the optimizing porosity distribution of a new type of gradient porous sintered copper fiber felt can greatly increase the methanol reforming reaction characteristics of hydrogen production,which confirmed the correctness of macroscopic numerical simulation method in this thesis.(4)The optimized design of the manufacturing gradient porous copper fiber sintering felt.Based on the above flow velocity field distribution,two kinds of porous copper fiber sintering felt with new topological structure are proposed.After coating its surface with Cu-Zn-Al-Zr system catalyst and loading it into the hydrogen micro-reactor,the hydrogen production experiment was also tested by the methanol reforming hydrogen test platform.The injection rate of 6-14ml/h,the reaction temperature is set to 260-260?,and then the relationship about the four major parameters and the porosity distribution was analyzed,which is including the methanol conversion rate,hydrogen flow rate,hydrogen selectivity and carbon monoxide concentration.Finally,the velocity field distribution of the two kinds of new porous copper fiber sintering felt is studied by using the macroscopic numerical simulation method.