Abstract:

At present, most renewable energy sources such as solar energy have intermittent and unstable problems, so high efficiency heat storage technology has become a key way to develop solar energy. Metal hydride high temperature heat storage technology, as one of the most promising methods of thermochemical heat storage, has been widely concerned. To realize the engineering application of metal hydride high temperature heat storage technology, it is necessary to investigate the transfer mechanism with hydrogen thermal coupling. In this paper, a multi-physical model of the reactor was established, and the variation law of the reactor parameters was obtained. By discussing the distribution of bed temperature and reaction fraction, the heat output of the reactor was divided into three stages: initial stage, platform stage and decline stage. At the same time, taking the peak point as the boundary, the initial stage can be divided into the initial rising stage and the initial descending stage. And the formation and movement mechanism of reaction front and the formation mechanism of inhomogeneous reaction were obtained. It can be concluded that hydrogen pressure, thermal contact resistance and bed thermal resistance are the control steps of corresponding stages. In addition, the variation of reactor parameters was obtained under different hydrogen pressure, thermal contact resistance and bed thermal resistance. Through comparative analysis, it was found that hydrogen pressure was the main parameter to regulate the maximum output temperature of the reactor. Compared with the thermal contact resistance, the bed thermal resistance showed more obvious effect on the heat output of the reactor. Finally, it was pointed out that to realize the engineering application, improving the thermal conductivity of the bed was the most promising choice to enhance the performance of metal hydride high temperature heat storage system.

Key words: solar energy, metal hydride, high temperature heat storage, transport, reactors, numerical simulation

摘要：

目前大多数可再生能源如太阳能具有间歇性和不稳定性的问题，因此高效蓄热技术成为了发展太阳能的一个关键途径。金属氢化物高温蓄热技术作为热化学蓄热中最有前途的方法之一，受到了人们的广泛关注。为了实现金属氢化物高温蓄热技术的工程应用，明确其氢热耦合传递机理至关重要。本研究采用数值模拟的方法，通过建立反应器的多物理场耦合模型，讨论了不同时刻下床层内部参数的分布，得到了反应锋面的形成和移动机理以及非均匀反应的形成机理；此外，结合反应器内部氢压、接触热阻和床层热阻的变化规律，明确了不同阶段下金属氢化物高温蓄热技术的控制环节；最后，依据金属氢化物高温蓄热技术的工程应用挑战，提出了相应的研究策略。

关键词: 太阳能, 金属氢化物, 高温蓄热, 传递, 反应器, 数值模拟