Common/Dependent-Pressure-Vessel Nickel-Hydrogen Batteries
- Thursday, 18 January 2007
One of the principal advantages would be high volumetric efficiency.
The term "common/dependent pressure vessel" (C/DPV) denotes a proposed alternative configuration for a nickel-hydrogen battery. The C/DPV configuration is so named because it is a hybrid of two prior configurations called "common pressure vessel" (CPV) and "dependent pressure vessel" (DPV). The C/DPV configuration has been proposed as a basis for designing highly reliable, long-life Ni/H2-batteries and cells for anticipated special applications in which it is expected that small charge capacities will suffice and sizes and weights must be minimized.The figure depicts examples of the proposed C/DPV configuration along with the CPV and DPV configurations and two other prior configurations called "individual pressure vessel" (IPV) and "single pressure vessel" (SPV). The following characteristics of the prior configurations are particularly relevant to the proposal of the C/DPV configuration:
- A DPV has a pocket-watch shape that is both advantageous and disadvantageous, in comparison with the shapes of the IPV, CPV, and SPV. The advantage is that a battery or cell can be made relatively flat and thin to fit in a thin space; the disadvantage is that a pressure vessel of this shape is not self-supporting and therefore must be mounted between objects that restrain it. DPV cells have not been widely used.
- The SPV and CPV configurations have been the basis of the established method for designing pressure vessels containing multiple cells.
Like the CPV and SPV configurations, the C/DPV configuration is one of multiple cells contained within a DPV. This configuration would afford the advantages and disadvantages of the DPV configuration (thinness and the need for mechanical restraint, respectively), while making it possible to use an electrolyte-containment system like that of the SPV. Although it is not readily apparent by visual examination of the figure, calculations have shown that for a given small charge capacity, the volumetric efficiency of a battery in the C/DPV configuration would exceed the volumetric efficiencies of batteries in the other configurations mentioned. Other anticipated advantages of the C/DPV configuration include improved thermal properties, greater simplicity and reliability (in comparison with the SPV configuration), lower costs associated with the simpler designs, and amenability to replacement and matching of cells.
This work was done by Paul J. Timmerman of Caltech for NASA's Jet Propulsion Laboratory. For further information, access the Technical Support Package (TSP) free on-line at www.techbriefs.com/tsp under the Computers/Electronics category. NPO-20769.
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