Lightweight Pressure Vessels Research Articles

Design Methods for Variable-Stiffness Super-Ellipsoidal Pressure Vessels Under Thermomechanical Loading

Pressure vessels are widely used in a broad range of applications in many industries, including possible use for hydrogen storage. Additionally, pressure vessels comprise non-circular-cross-section fuselages such as in blended-wing–body aircraft. Failure performance, weight, and packing efficiency are important factors that should be considered when designing pressure vessels. Often, lightweight pressure vessels maximize their volume for a given available space volume and withstand substantial internal pressure. Bend-free super ellipsoids of revolution, enabled by stiffness tailoring via variable-angle tow placement of composite plies, present an appealing solution that makes them possible candidates for future composite pressure vessels. To date, the bend-free design methodology for super ellipsoids of revolution has only been developed under uniform internal pressure loading. However, in reality, pressure vessels can also be subjected to thermal loads during service. Therefore, this study develops an initial bend-free design methodology for super ellipsoids of revolution that are subjected to both uniform internal pressure and thermal loads.

Performance index optimization of pressure vessels manufactured by filament winding technology

Filament-wound pressure vessels represent the proper choice to obtain good mechanical properties and lightweight. The pressure vessel geometry is generally cylindrical and the wall is composed of a ‘liner’ and a ‘shell.’ The liner holds the gas and guards the shell from chemical attacks. The filament-wound shell aims to withstand the hydrostatic load of pressure gas. The shell design has to be defined in observance of both fibers stratification methodology and design structural criteria. For years, pressure vessel design primarily focused on mass; space saving features during pressure vessel design was usually a secondary concern unless specifically required by the customer. Now, more emphasis have being assigned to design light weight pressure vessels that also maximizes use of available space for industry finding such as space on a spacecraft, as well as mass, is at premium. For this reason, it is very important to optimize together the index of performance and packaging of gas storage system. This work aims to develop a parametric method to optimize the index of performance as a function of one or more pressure vessels; in this way, it is possible to optimize also the packaging of the gas storage system.

Reversible (unitised) PEM fuel cell devices

Regenerative fuel cells (RFCs) are enabling for many weight-critical portable applications, since the packaged specific energy (>400 Wh/kg) of properly designed lightweight RFC systems is several-fold higher than that of the lightest-weight rechargeable batteries. RFC systems can be rapidly refueled (like primary fuel cells), or can be electrically recharged (like secondary batteries) if a refueling infrastructure is not conveniently available. Higher energy capacity systems with higher performance, reduced weight and freedom from fueling infrastructure are the features that RFCs promise for portable applications. Reversible proton exchange membrane (PEM) fuel cells, also known as unitised regenerative fuel cells (URFCs), or reversible regenerative fuel cells, are RFC systems which use reversible PEM cells, where each cell is capable of operating both as a fuel cell and as an electrolyser. URFCs further economise portable device weight, volume and complexity by combining the functions of fuel cells and electrolysers in the same hardware, generally without any system performance or efficiency reduction. URFCs are being made in many forms, some of which are already small enough to be portable. Lawrence Livermore National Laboratory (LLNL) has worked with industrial partners to design, develop and demonstrate high-performance and high-cycle-life URFC systems. LLNL is also working with industrial partners to develop breakthroughs in lightweight pressure vessels that are necessary for URFC systems to achieve the specific energy advantages over rechargeable batteries. Proton Energy Systems Inc is concurrently developing and commercialising URFC systems (its Unigen ; product lproduct line), in addition to PEM electrolyser systems (the Hogen ; product lproduct line), and primary PEM fuel cell systems. LLNL is constructing demonstration URFC units in order to persuade potential sponsors, often in their own conference rooms, that advanced applications based on URFCs are feasible. Safety and logistics force these URFC demonstration units to be small, transportable and easily set up, hence they already prove the viability of URFC systems for portable applications.

Regenerative Fuel Cell Systems

Regenerative fuel cell (RFC) systems produce power and electrolytically regenerate their reactants using stacks of electrochemical cells. Energy storage systems with extremely high specific energy (>400 Wh/kg) have been designed that use lightweight pressure vessels to contain the gases generated by reversible (unitized) regenerative fuel cells (URFCs). Progress is reported on the development, integration, and operation of rechargeable energy storage systems with such high specific energy. A primary fuel cell test rig with a single cell (46 cm2 active area) has been modified and operated reversibly as a URFC (for up to 2010 cycles on a single cell). This URFC uses bifunctional electrodes (oxidation and reduction electrodes reverse roles when switching from charge to discharge, as with a rechargeable battery) and cathode feed electrolysis (water is fed from the hydrogen side of the cell). Lightweight pressure vessels with performance factors (burst pressure × internal volume/tank weight) > 50 km (2.0 milli...

Fifth world hydrogen energy conference 15–19 July 1984 division D “conversion and utilization”. The development and practical application of fuel cells: Keynote address

This paper is concerned only with hydrogen fuel cells, and it is suggested that the most likely commercial application will initially be for the propulsion of short-range city traffic, especially buses. For a start, it seems likely that the hydrogen will be stored as a compressed gas, using the latest developments in lightweight pressure vessels, although other methods of hydrogen storage will probably follow, for example metal hydrides. It is suggested that fuel cells are still in an early stage of development, and that considerable improvements should be achieved in the future, as experience is accumulated from the use of fuel cells in space, and other special applications. The use of pure hydrogen in fuel cells probably means that this will provide a new and improved method of energy storage, when compared with conventional storage batteries; and advantage would naturally be taken of the great improvements which are now being made in the design of electrolyzers, which should help to reduce the cost of pure hydrogen, especially in countries such as Canada, which have large reserves of hydro-electric power and a successful nuclear power industry.

Design and Fabrication of Welded Lightweight Pressure Vessels

Design and Fabrication of Welded Lightweight Pressure Vessels