Numerical Performance Simulation of a Metal Hydride Reactor with Spatially Distributed Metal-foam Volume Fraction

論文翻譯標題: 發泡金屬體積比空間分佈對金屬氫化物儲氫系統效能影響之數值分析
  • 莊 凱茜

學生論文: Master's Thesis


Hydrogen is regarded as an ideal choice of alternative energy because it is highly abundant environmentally friendly and possesses high calorific value Among existing methods of storage metal hydride systems are thought to be effective due to their high volumetric capacity and safety However significant heat energy exchanges occur during the hydrogen storing and releasing processes and hence thermal management becomes a serious issue in metal hydride reactors (MHRs) In this study metal foam is added in the reactors to augment the overall thermal conductivity and to improve the heat transfer behavior in the reactor To examine the effect of metal foam addition a 2-D mathematical model is constructed and used to simulate the hydriding process of MHRs by means of COMSOL Multiphysics software Previously it was found in works of our group that there exists an “optimal” volume fraction of metal foam (?_mf) to minimize the charging time if a prescribed amount of hydrogen is to be stored in the reactor Besides it is also found that a spatially varying ?_mf distribution will reduce the charging time of the reactor with a given overall ?_mf Combining those two findings we expect a further improvement in the adsorption rate of MHRs with spatially distributed ?_mf based on the optimal choice of ?_mf obtained before It is shown that the effectiveness of spatially ?_mf distributions is no longer powerful when ?_mf is close to the optimal value and the heat transfer rate has not much room for further enhancement In addition it is found that the optimal distribution resulting in the shortest charging time is actually determined under the compromise of the heat transfer and fluid flow rate To measure quantitatively the relative importance of thermal and fluid resistances a parameter (ω) is defined It is then shown that ω is not only affected by the value of ?_mf but also by the hydrogen storage capacity and the size of the MHR The concept of ω therefore can help expedite the determination of the optimal ?_mf distribution and thus is useful to the design of MHRs
獎項日期2016 五月 4
監督員Tian-Shiang Yang (Supervisor)