金属氢化物反应器吸氢过程的热质传递特性分析

Analysis on Heat and Mass Transfer Characteristics of Metal Hydride Reactors During Adsorption

为了研究金属氢化物反应器内吸氢过程的热质传递特性,建立了圆柱形反应器的二维多物理场模型.新建立的模型考虑了换热流体流速与温度变化对反应器吸氢过程的影响,采用COM-SOL Multiphysics V3.5a软件来求解,并探讨了一些重要参数变化对反应器性能的影响.结果表明:接近换热管壁处的氢化物床的温度较低,吸氢反应更快,换热流体入口附近床层的吸氢反应比出口附近的快;减小氢化物床层与换热管壁面之间的接触热阻和增加氢化物床层有效导热系数都可以增强换热效果,从而加快吸氢反应,当接触热阻从0.002m2.K/W减小到0.000 5m2.K/W时,吸氢反应时间大约缩短了15.5%;采用强化换热措施可以减少吸氢反应时间,提高反应器平均功率.

The two-dimensional multi-physics model of a cylindrical metal hydride reactor during adsorption was presented to study heat and mass transfer characteristics of metal hydride reactors. In this model, the effects of velocity and temperature changes of heat transfer fluid on the hydrogen adsorption process were considered. The model was numerically solved using the COMSOL Multiphysics V3.5a, and the effects of some important parameters on the reactor performance were discussed. The results show that the hydrogen adsorption reaction is faster near the heat exchanger tube wall where the bed temperature is lower. Moreover, the reacted fraction of the bed near the heat transfer fluid inlet is higher than that near the outlet. Both reducing the thermal contact resistance between the hydride bed and the heat exchanger tube wall and increasing the effective thermal conductivity of the hydride bed can improve the heat transfer performance and accelerate the adsorption process. When the thermal contact resistance decreases from 0. 002 m2 · K/W to 0. 000 5 m2 · K/W, the hydriding time drops by about 15.5%. For metal hydride reactors, adopting heat transfer enhancement measures can reduce the hydriding time and increase the average power.