Energy Dense, Lighweight, Durable, Systems for Storage and Delivery of Hydrogen

[摘要] The work presented in this report summarizes the current state-of-the-art in on-board storage on compressed gaseous hydrogen as well as the development of analysis tools, methods, and theoretical data for devising high performance design configurations for hydrogen storage. The state-of-the-art in the area of compressed hydrogen storage reveals that the current configuration of the hydrogen storage tank is a seamless cylindrical part with two end domes. The tank is composed of an aluminum liner overwrapped with carbon fibers. Such a configuration was proved to sustain internal pressures up to 350 bars (5,000 psi). Finite-element stress analyses were performed on filament-wound hydrogen storage cylindrical tanks under the effect of internal pressure of 700 bars (10,000 psi). Tank deformations, stress fields, and intensities induced at the tank wall were examined. The results indicated that the aluminum liner can not sustain such a high pressure and initiate the tank failure. Thus, hydrogen tanks ought to be built entirely out of composite materials based on carbon fibers or other innovative composite materials. A spherical hydrogen storage tank was suggested within the scope of this project. A stress reduction was achieved by this change of the tank geometry, which allows for increasing the amount of the stored hydrogen and storage energy density. The finite element modeling of both cylindrical and spherical tank design configurations indicate that the formation of stress concentration zones in the vicinity of the valve inlet as well as the presence of high shear stresses in this area. Therefore, it is highly recommended to tailor the tank wall design to be thicker in this region and tapered to the required thickness in the rest of the tank shell. Innovative layout configurations of multiple tanks for enhanced conformability in limited space have been proposed and theoretically modeled using 3D finite element analysis. Optimum tailoring of fiber orientations and lay-ups are needed to relieve the high stress in regions of high stress concentrations between intersecting tanks/ tank sections. Filament winding process is the most suitable way for producing both cylindrical and spherical hydrogen storage tanks with high industrial quality. However, due to the unavailability of such equipment at West Virginia University and limited funding, the composite structures within this work were produced by hand layup and bag molding techniques. More advanced manufacturing processes can significantly increase the structural strength of the tank and enhances its performance and also further increase weight saving capabilities. The concept of using a carbon composite liner seems to be promising in overcoming the low strength of the aluminum liner at internal high pressures. This could be further enhanced by using MetPreg filament winding to produce such a liner. Innovative designs for the polar boss of the storage tanks and the valve connections are still needed to reduce the high stress formed in these zones to allow for the tank to accommodate higher internal pressures. The Continuum Damage Mechanics (CDM) approach was applied for fault-tolerant design and efficient maintenance of lightweight automotive structures made of composite materials. Potential effects of damage initiation and accumulation are formulated for various design configurations, with emphasis on lightweight fiber-reinforced composites. The CDM model considers damage associated with plasticity and fatigue.

[发布日期] 2008-12-31

[学科分类] 再生能源与代替技术