Fuel cells are a promising energy source for automotive and portable applications. Since fuel cells use hydrogen, they offer the potential to reduce the dependence on traditional petroleum. In addition, the only emission from fuel cell operation is water and hence they do not produce greenhouse gases and can also help to mitigate urban air pollution. However, hydrogen storage is a very significant barrier to creating a hydrogen energy economy. Particularly for onboard applications, current hydrogen storage methods including gas compression and liquefaction are not optimal because they are not only energy-intensive and expensive but presenting safety issues. A promising alternative is solid-state hydrogen storage, which utilizes metal hydrides to absorb/desorb hydrogen at relatively low pressure offering safety and cost advantages with potentially unparalleled hydrogen storage density.
Hydrogen storage in porous metal hydrides beds is a complex problem involving compressible gas flow in porous media, heat transfer and reaction kinetics. And heat transfer is the key obstacle to the development of metal hydride storage systems, because the charging time of hydrogen in metal hydride tanks is strongly influenced by the heat removal rate from the reaction bed. The overall objective is to improve the rate at which the hydrogen gas can be charged into a hydride-based hydrogen storage tank. In order to accomplish this goal, we are formulating a model as shown in Figure 1 that incorporates flow, reaction kinetics, and heat transfer to find the optimal tank design and materials that will accelerate the charging rate of hydrogen into the tank, meanwhile a basic experiment apparatus as shown in Figures 2 and 3 is built to validate the model’s result.
Figure 1: Schematic of a cylindrical metal hydride tank containing two layers of spirally coiled tubes embedded with optimized concentric fins using the Genetic Algorithm Method.
Figure 2: Test apparatus for model validation.
Figure 3: Cross section of the test apparatus.