Proposal for the characterization of a hydrogen storage system based on a hydride forming material using the neutrography technique.

BIASETTI, A.T.; BORZONE, E.M.; MARÍN J.; BARUJ A.; MEYER, G.O.

Cartagena

Taller; ICTP Caribbean School on Materials for Clean Energy; 2019

ICTP

Hydrogen storage by means of chemical absorption in hydride forming materials (HFM), is one of the most investigated and promising ways to solve many issues related to Hydrogen Technologies. Several of those are focused on the development of a Hydrogen Economy, in order to overcome the enviromental problems derived from the use of fossil fuels. This is because the hydrogen is a clean and renewable fuel with high energy density compared to conventional energy sources. One of the main  challenges of this field is the improvement of the operating setup conditions for a practial use of potential hydrogen reservoirs based on a HFM.  An advantage of the AB5  -HFM type, is that these materials allow the hydrogen to be reversibly stored under relative low pressure and at room temperature. In practical situations, during the reversible reactions of hydrogen uptake and release, the external pressure remains almost constant. This technological advantage leads, however, to a practical problem: knowing the level of hydrogen filling through the mesurement of small changes in pressure during the reactions.     On the other hand, these materials exhibit a considerable change in relative bulk volume during the hydriding/dehydriding processes ( 21% in the case of LaNi5).  As a consequence of this, it is imposed significant stress upon the walls of the container where the powder material is placed. While many researchers have been studied how to avoid the damage of the container due to this phenomena, it was proposed to take advantage of this property in order to determine indirectly the level of hydrogen filling of the HFM placed in the selaed container. Specifically, for this Project it was designed a cylindrical aluminium vessel for it to be elastically deformed during the expansión of  the material. The strain states generated upon the container can be monitored by using strain gauges sensors located along the external walls. The use of powder material inside of the vessel requieres further studies to ensure repeatability since the material becames gradually refined along the initial hydrogen absorption/desorption cycles.    Finally, it was proved that neutrography is an efficient technique in order to visualize the evolution of the material whitin the container. It helps for the understanding of the hydriding/deydriding front advance during  each of the processes and it also brings valuable information to state a correlation between the strains states and the level of hydrogen filling of the material. The right  correlation between the effect described and the voltage signal obtained, is a key to transmit information from inside the container to the outside.    In this work, we present preliminary results obtained in our laboratory and the proposal for the experiments to be performed in the neutrography facility of RA-6 experimental reactyor at Centro Atómico Bariloche