METAL HYDRIDE ENERGY-SYSTEMS PERFORMANCE EVALUATION .A. DYNAMIC ANALYSIS MODEL OF HEAT AND MASS-TRANSFER

This paper presents a numerical model to evaluate the dynamic behaviou r of heat and mass transfer in metal hydride energy systems. At first, with reference to each metal hydride reactor (i.e. heat exchanger fil led with metal hydride), both the equations which describe the hydroge n absorption-desorption and the heat transfer are derived. Then, the ' 'core'' of metal hydride energy systems, i.e. coupled metal hydride re actors, has been considered and, by the use of the previous correlatio ns and by further equations taking into account the transient phenomen a in the gaseous hydrogen line linking the reactors, the complete nume rical modelling has been carried out. This model, founded on a typical thermodynamic approach, is a lumped-parameters model. and thus its nu merical resolution is rather easy and fast. The numerical model is abl e to take into account the fundamental determinants of coupled metal h ydride operations: the dynamic of hydrogen transfer between paired met al hydride containers and the dynamic of the heat transfer process in the containers. Thus the model allows us to know and to foresee the ef fects of operational and design parameters on the mass and heat transf er performance of the metal hydride energy systems. The validation of the model has been carried out by comparison with experimental results obtained by other authors and the results of this validation procedur e, which are in good agreement with the experimental ones, are present ed and discussed.