| 摘要: | 研究期間：10108~10207;Depletion of fossil fuels and environmental issues related to the emission of the green-house effect gas have led to great research efforts on alternative and cleaner fuels. The intermittence disadvantages of solar energy, wind power, wave power, etc need to be compensated by good schemes of energy storage. Hydrogen, as an ideal energy carrier, is promising in energy storage in the future, and also is a clean fuel once produced, which generates only water when burnt with oxygen in combustion chambers or fuel cells. For transmission, hydrogen stored as metal hydrides is a potent candidate for its advantages in safe and reliability and being able to offer high volumetric energy density compared to the conventional ways of high pressure gas and liquefaction. In the usage of metal hydrides for hydrogen storage, heat transfer issues cannot be ignored as metal hydriding/dehydriding inevitably involves exothermic/endothermic reactions. In the absorption case, an increase in temperature due to the heat release may raise the equilibrium pressure so high that the hydriding process is ceased. On the other hand, a temperature decrease in the endothermic desorption reaction can bring the equilibrium pressure too low for the dehydriding process to proceed. In order to increase the reaction surfaces, metal hydrides are in the form of powders when put in the vessels. Due to usually the very low thermal conductivities of metal powder beds, a thorough understanding of the effective thermal conductivities of metal hydride beds is crucial to the success of the metal hydride hydrogen vessel design. This proposal will address the key technical challenges in designing the metal hydride hydrogen vessels. The whole plan comprises three major parts and will be completed in three years. The first part includes setting up an experiment system for determining the effective thermal conductivities of metal hydride beds. As the effective conductivity is a function of the hydrogen pressure, concentration and temperature, the measurements will couple the hydrogen charging/discharging processes, which increases the complexity of the experiments. As the second part of the research plan, a mathematical model will be set up for describing the thermal fluid behavior in the metal hydride hydrogen storage vessels. The model will includes the effective thermal conductivity data obtained in the first part of the project. Based on the mathematical work, a computer-aided-engineering (CAE) scheme will be established, which is aimed to facilitate the design and analysis of novel storage vessels, saving experimental efforts as before by traditional trial-and-error methods. Results of simulation will be compared with the experiments to correct the modeling details. Following the previous two works, the third part of the research plan is to set up a comprehensive design and analysis protocol that combines mathematical modeling, computational simulation and experimental verification as to interpret the entire processes of hydrogen absorption/desorption in storage vessels. By completion of the research period in three years, it is expected that a novel hydrogen storage reactor containing metal hydrides will be designed and made in house to fulfill the perspective hydrogen usage in fuel cells. The research results will be of important contribution to the advances of hydrogen storage technology, specifically helping improve heat transfer enhancement of metal hydride reactors. |
