耦合相变储热的金属氢化物反应器吸氢过程模拟

A transient two-dimensional mathematical model of solid-state hydrogen storage reactor coupled with phase-change material (PCM) as heat exchanger was developed on the basis of metal hydride hydrogen absorption reactions. The influences of the operating and thermophysical parameters, including the initial hydrogen pressure, the PCM melting temperature, PCM solid (liquid) thermal conductivity and melting enthalpy, on the hydrogen absorption performances of the reactor were further investigated. The simulation results showed that different thermophysical parameters of PCM affect the reactor performance in varying degrees. The influences of the PCM solid thermal conductivity and melting enthalpy on the hydrogen absorption behavior of the reactor were small, while the PCM melting temperature and liquid thermal conductivity had a great impact on the hydrogen absorption process. It was found that the hydrogen storage reactor presented an improved hydrogen absorption behavior when the PCM melting temperature was reduced or the PCM liquid thermal conductivity becomes large. This is because that both the reduction of the PCM melting temperature and the increase of the PCM liquid thermal conductivity help to enhance the heat transfer between metal hydride and PCM, thus facilitating the hydrogen absorption reaction in the reactor. By contrast, the larger PCM solid thermal conductivity only accelerates the temperature rise process of the PCM and has few influences on the hydrogen absorption reaction of metal hydride. Besides the thermophysical parameters of PCM, the operating parameter such as hydrogen pressure also presents a great impact on the reactor performance. Improving the hydrogen pressure under the conditions of the optimized PCM thermophysical properties contributes to the improvement of the reaction rate, which subsequently enhances the heat transfer between metal hydride and PCM. Through the parametric analyses, the key affecting parameters and their optimization strategy are obtained for the metal hydride reactor coupled with the PCM as heat exchanger, which is significant and valuable for the development of advanced hydrogen storage reactors.