Numerical study of thermal effects in cryo-adsorptive hydrogen storage tank

Hydrogen storage is an important issue in the practical application of hydrogen technology. Among various hydrogen storage technologies, the cryo-adsorptive hydrogen storage appears to have huge potential for a further research because of its high storage capacity at low pressure. In this study, a computational fluid dynamics model and a lumped parameter model are developed to simulate the cryo-adsorptive hydrogen storage processes. These two models are implemented on the FLUENT (TM) platform and MATLAB/SIMULINK (TM) environment, respectively. The thermodynamic behavior and thermal effect during the cryo-adsorptive hydrogen storage processes in a cryo-adsorption storage system are analyzed. Two adsorbents, activated carbon (Norit R0.8) and metal-organic-framework (Cu-BTC), have been studied. The pressure increases quickly at early stage and then keeps steady during the slow filling process. The temperature has larger gradient in the radial and smaller gradient in the axis. During the fast filling process, the release of adsorption heat leads to the temperature increasing in a short time when there is not enough time for efficient heat transfer; during the slow filling process, heat transfer becomes the main factor of temperature change. The effect of mass flow rate on temperature is more significant at the location near tank wall than the center location of the tank. A better external heat transfer condition and higher bed thermal conductivity lead to lower temperature level which will increase the adsorption capacity. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4798425]