Fractal Construction Of Microchannel Reactor With Porous Surface For Hydrogen Production And Study On Heat And Mass Transfer Characteristics

Microreactor for hydrogen production from methanol reforming is considered to be the key to solve the problem of hydrogen supply for hydrogen fuel cell vehicles.Microreactor has the advantages of small size,high energy density and low manufacturing cost.The reaction support is the core component of the microreactor.The research work is supported by the National Nature Science Foundation of China(Grand No.51575482),and a one-step forming process for microchannel catalyst supports with porous surface was proposed.What's more,a numerical model for characterizing porous surfaces was also proposed based on fractal geometry,which is consistent with the actual surface in porous shape,distribution and macroscopic characteristics.Then the fluid flow and heat transfer characteristics and hydrogen production performance of the microchannel reactor with porous surface were analyzed by FEM.The effects of different NaCl particles on the fluid flow and heat transfer characteristics and hydrogen production performance of the reactor were analyzed in detail.The experimental systems of flow and heat transfer characteristics and hydrogen production were also established,and the reaction supports manufactured by different NaCl powders were experimentally studied.The experimental system of fluid flow and heat transfer characteristics and hydrogen production was also established.The reaction supports made of different NaCl particals were studied experimentally.In Chapter 1,the background and significance of the study were introducted,the research status of microchannel catalyst support fabrication,porous surface fabrication,characterization and the fluid flow and heat transfer characteristics of a microreactor were reviewed.Then,the research objectives,contents and framework of this dissertation were proposed.In Chapter 2,a one-step manufacturing process for microchannel catalyst supports with porous surface was proposed.By observing the morphology of porous surface,it was verified that the porous surface made of different NaCl particles have obvious differences in pore size,specific surface area and tortuosity.And it was proved that the porous surface fabricated by layered powder sintering and dissolution method has strong fractal characteristics.A fractal element for describing porous surfaces was constructed.In Chapter 3,the structure of microchannel reactor with porous surface for hydrogen production was described.Based on fractal theory and fractal element,a model of microchannel reactor with porous surface was established.The FEM of the fluid flow and heat transfer characteristics was carried out.The effects of porous surface pararmeters on the fluid flow and heat transfer characteristics of the reactor were studied.In Chapter 4,a microchannel reactor with porous surface for hydrogen production was fabricated.An experimental system for fluid flow and heat transfer characteristics was built.The effects of porous surface on the fluid flow and heat transfer characteristics of the microreactor were studied experimentally.The res?lts were analyzed and compared with the sim?lation res?lts.In Chapter 5,the fractal model of microchannel reactor with porous surface was established.The process of hydrogen production was analyzed by FEM using FLUENT.And an experimental system for hydrogen production by microchannel reactor with porous surface was built.The effect of porous surface on the hydrogen production performance of methanol reforming was studied experimentally and compared with the sim?lation res?lts.It provideed a basis for optimizing the manufacturing process of layered powder and sintering dissolution method.In Chapter 6,The main work of the dissertation was summarized,and the future work was prospected.