Hydrodynamic And Heat Transfer Characteristics Of Dual-gradient Porous Structure For On-line Hydrogen Production

The new energy industry is a hot field that is gradually emerging.In this field,hydrogen energy is one of the frontiers.The method for preparing hydrogen by using liquid fuel through reforming catalysis is currently one of the commonly used methods,but the performance of the catalyst-carrying carrier has always restricted the improvement of catalytic efficiency.Therefore,the development of catalytic carriers with high catalytic efficiency is a direction of practical value.The current improvement of the catalytic support is to use a porous structure as a catalyst support,and then assist some other processes to attach the catalyst to the support surface,thereby forming a highly efficient catalytic core.Aiming at the fluid dynamics and heat transfer properties of porous structures,this study proposes a dual-gradient porous structure,and theoretically studies and verifies the corresponding fluid dynamics and heat transfer characteristics.The main independent variable studied in this paper is porosity,and the corresponding dependent variables are flow velocity,Reynolds number,Darcy friction factor,and pressure change in fluid dynamics.It also includes heat transfer rate,Nusselt number,and general Rand number,convective heat transfer coefficient and temperature change.In the first chapter,the historical background and manufacturing process of porous structure are summarized first,and the incomplete status quo of some theories is introduced.At the same time,the research background and significance of this thesis,the current research status at home and abroad,and the source of the subject are put forward.In chapter two,some of the fluid dynamics that are mainly explained in this paper may be used in classical theories,including velocity boundary layer theory and thermal diffusion equations.In addition,the flow velocity,Reynolds number,Darcy friction factor and pressure change in fluid dynamics and heat transfer rate,Nusselt number,Prandtl number,convective heat transfer coefficient and temperature change in heat transfer are described in detail.Its basic principle paves the way for the overall and specific structure of the dual-gradient porous structure described below.In chapter 3,the overall properties of the dual-gradient porous structure are studied,and the wet cycle governing equations are proposed in the traditional boundary layer theory and thermal diffusion theory.The results show that the wet cycle governing equation can effectively reduce the error between theoretical analysis and actual calculation,and provide a certain reference for the subsequent analysis of specific structures.In chapter four,a specific dual-gradient porous structure is proposed,and based on more in-depth theories,an area-based macro temperature statistical formula is proposed.The results show that the formula can effectively reduce the errors caused by specific models.In addition,a quantity permutation coefficient is also proposed.The quantity permutation coefficient itself is not a number that measures the quantity between two systems,but a measure of the arrangement between the two systems,especially the arrangement and size ratio in a finite plane.A coefficient set based on the relationship.If the number arrangement coefficients of the two systems are equal,it means that the arrangement manner and scale ratio of the two systems are completely the same.In Chapter 5,the numerical and theoretical analysis of the theories proposed in Chapters 3 and 4 are performed.The continuous equations are analyzed using the average discretization interpolation method.The main conclusions obtained are as follows: First,the dual-gradient porous structure It can effectively increase the collision frequency between the fluid and the solid wall to increase the reaction rate.Second,the dual body porous structure can reduce the power of the external pump.Third,the wet-period governing equation and area-based macro temperature statistical formula can effectively reduce the errors in theoretical analysis and numerical calculation.Chapter VI summarizes the main work and conclusions of the full text,and puts forward future work prospects.