Theoretical Study And Design Optimization Of Micro-Reactor With Micro-Pin-Fin Arrays For Hydrogen Production Via Methanol Reforming

Fuel cell vehicles have attracted widely attention due to excessive consumption of fossil fuel such as oil and environmental pollution aggravation. At present, there are some shortcomings for fuel processors to supply hydrogen for fuel cell vehicles, such as large volume, low energy density and high production cost, which could not meet the demands of compactness and lightweight for removable hydrogen source. Thus, the theoretical modelling and experiments are carried out to study the topological design, micro thixo-forming forming and heat and mass transfer characteristics of micro-reactor with micro-pin-fin arrays for hydrogen production via methanol reforming in this dissertation. The research work is supported by the National Natural Science Foundation of China (Grant No.50930005), the Natural Science Foundation of Zhejiang Province (Grant No. Z1090373) and the Research Fund for the Doctoral Program of Higher Education of China (Grant No.20110101110011).In chapter 1, the research background and significance of the dissertation were introduced, the research status and development trend of topological design, micro thixo-forming forming, heat and mass transfer characteristics and flow manifold optimization were estimated in detail. Then, the main research contents and Architecture between the chapters of this dissertation were put forward.In chapter 2, a micro-reactor with micro-pin-fin arrays for hydrogen production via methanol reforming was developed. The three-dimensional heat and mass transfer model was established for the micro-reactor. The effects of thermodynamic parameters on the hydrogen production performance of micro-reactor via methanol reforming were obtained and the comparisons of hydrogen production performance between micro-channel reactor and micro-reactor with micro-pin-fin arrays were carried out.In chapter 3, for studying the effect of micro-pin-fin arrays on the hydrogen production performance of micro-reactor, a material balance model for hydrogen production via methanol reforming based on plug flow model was established, and the structural effects of micro-pin-fin arrays on hydrogen production performance of micro-reactor via methanol reforming were obtained.In chapter 4, for velocity optimization of micro-reactor with micro-pin-fin arrays for hydrogen production via methanol reforming, a model between flow manifold structure of reaction channel and velocity distribution of micro-pin-fin arrays was developed by adopting a simplified resistance network model, and the effects of manifold structure of reaction channel on velocity distribution of micro-pin-fin arrays were analyzed. Based on the established model, a optimizing strategy of flow manifold structure was proposed and the optimized flow manifold structures were obtained under the condition of different micro-pin-fin arrays.In chapter 5, aiming at the heating problem of micro-reactor, a self-heated micro-reactor with micro-pin-fin arrays was proposed. A three-dimensional flow and heat transfer model of the micro-reactor was established and simulated by computational fluid dynamics program. The structural effects of micro-pin-fin arrays on the flow and heat transfer characteristics were obtained.In chapter 6, to realize the’scale up’ of micro-reactor, a self-heated laminated micro-reactor with micro-pin-fin arrays was proposed. Aiming at the problem of velocity maldistribution in self-heated laminated micro-reactor with micro-pin-fin arrays for hydrogen production via methanol reforming, the relationship model was established between the flow passage structure and the contact time and hydrogen production performance, and the effects of structural parameters of flow passage on contact time distribution and hydrogen production performance were analyzed. Two-scale flow passage was proposed since one-scale flow passage can’t unify the contact time in micro-reactor when reforming channel number was large. By analyzing the contact time distribution, the better flow passage structure was obtained under the condition of two-scale flow passage structure.In chapter 7, catalyst support with micro-pin-fin arrays was fabricated by the semi-solid micro thixo-forming process and assembled to be a micro-reactor with micro-pin-fin arrays. The hydrogen production system of micro-reactor via methanol reforming was developed. The effects of thermodynamic parameters and structural parameters of micro-pin-fin arrays on the hydrogen production performance via methanol reforming were studied by a series of experiments. What’s more, The self-heated hydrogen production system of micro-reactor via methanol reforming was developed. the experiments of hydrogen production via methanol reforming were carried for the designed self-heated micro-reactor and the study showed the self-heated operation of the self-heated micro-reactor with micro-pin-fin arrays. The experiments done in Chapter 7 verified the theoretical models the preceding chapters developed.In chapter 8, the main research work of this dissertation was summarized and prospected.