Experimental and numerical analysis of dynamic metal hydride hydrogen storage systems

This paper examines the dynamics of metal hydride storage systems by experimentation and numerical modelling. A specially designed and instrumented metal hydride tank is used to gather data for a cyclic external hydrogen load. Thermocouples provide temperature measurements at various radial and axial locations in the metal hydride bed. This data is used to validate a two-dimensional mathematical model previously developed by the authors. The model is then used to perform a parametric study on some of the key variables describing metal hydride systems. These variables are the equilibrium pressure, where the tails and concentration dependence are investigated, and the effective thermal conductivity of the metal hydride bed, where the pressure and concentration dependence are analyzed. Including tails on the equilibrium pressure curves was found to be important particularly for the accuracy of the initial cycles. Introducing a concentration dependence for the plateau region of the equilibrium pressure curve was found to be important for both pressure and temperature results. Effective thermal conductivity was found to be important, and the inclusion of pressure and concentration dependence produced more precise modelling results.