Experimental study of porosity and effective thermal conductivity in packed bed of nano-structured FeTi for usage in hydrogen storage tanks

The porosity and effective thermal conductivity, which were measured simultaneously, changed owing to expansion during hydrogen absorption and contraction during hydrogen desorption. The metal hydride used in the experiment was a newly developed nano-structured FeTi (n-FeTi) by mechanical alloying. The porosity was measured by directly observing the changes in the volume of a metal hydride packed bed under free expansion. In the authors' previous study of LaNi s , the volume of the packed bed gradually increased, whereas the total volume of the n-FeTi packed bed decreased with increase in the cycles of expansion and contraction. The effective thermal conductivity measurements of the metal hydride packed bed were carried out using a cylindrical device with heating from a central heater. The results showed that the effective thermal conductivity of n-FeTi changes from 0.4 to 1.1 W/mK with rise in reacted fraction and decrease in porosity. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.