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Experimental Tests on High Temperature Hydride Hydrogen Storage System

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Experimental Tests on High Temperature Hydride Hydrogen Storage System

System Maurizio Verga*, Cristina Guardamagna *, Fabio Armanasco *, Carmen Valli *, Alvise Bianchin **, Sergio Lo Russo ***, Amedeo Maddalena **, Giovanni Principi ** WHTC 2007, Montecatini 4-7 Novembre 2007 *CESI RICERCA **Settore Materiali, Dipartimento di Ingegneria Meccanica, Università di Padova, Italy ***Dipartimento di Fisica, Università di Padova CESI RICERCA is developing, in collaboration with the Hydrogen Group of Padova University, a research program to evaluate metal hydride storage systems potentiality in stationary applications. A test facility operating up to 350°C with a hydrogen storage system capacity of 350 Nl has been designed and used in experimental tests of high temperature Mg-based metal hydrides. The facility allows fully automated hydrogen absorption and desorption cycles to be carried out and is particularly suitable to evaluate cycling effects on storage capability. Storage geometry design has been optimised in order to improve thermal exchange capabilities and minimise scale-up effects essentially due to metal hydride low thermal conductivity. As a first step of scale-up effects evaluation, experimental tests have been performed on 500 g of ball milled MgH 2 hydride powder catalysed with Nb 2 O 5 to improve kinetic behaviour. The hydride has been activated in the facility itself and absorption and desorption cycles at different temperature and pressures values have been tested to evaluate system thermodynamics and optimise operating parameters. Hydride absorption/desorption enthalpy has been evaluated for the whole system by means of measurements on heat transfer fluid. Different heating and cooling ramps have been tested in order to minimise scale effects (e.g. hydride temperature inhomogeneity) and to reach maximum performance without hydride degradation. In view of stationary applications, different conditions that optimise hydrogen discharge pressure and system kinetics have been tested, in particular verifying the effects of different hydride temperatures in desorption cycles. The optimised conditions have been finally used as reference and storage system degradation has been evaluated by means of several absorption and desorption cycles. This work has been financed by the Ministry of Economic Development with the Research Fund of the Italian Electrical System under the Contract Agreement established with the Ministry Decree of March 23, 2006.

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