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Valdez, T.

Publications and source records attributed to Valdez, T..

14 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1998

Mars Pathfinder Battery Performance

Contents include the following: (1) mission requirements; (2) battery design features; (3) battery operational overview; (4) battery performance; and (5) summary and conclusions.

Otzinger, Burton↗
NASA NTRS1997

Commercialization of a Direct Methanol Fuel Cell System

This paper describes a major breakthrough in energy technology developed at the Jet Propulsion Laboratory that can be used in a wide variety of portable, remote, and transportation applications without polluting the environment. The status, performance, and design considerations of the JPL non-polluting, direct methanol, fuel cell system for consumer equipment and transportation applications are reported herein. This new fuel cell technology utilizes the direct oxidation of a 3 percent aqueous liquid methanol solution as the fuel and air (O&sub2;) as the oxidant. The only products are CO&sub2; and water. Therefore, because recharging can be accomplished by refueling with methanol, vehicles can enjoy unlimited range and extended use compared to battery operated devices requiring recharging time and power accessibility.

fuel↗
NASA NTRS1996

Low Crossover Polymer Electrolyte Membranes for Direct Methanol Fuel Cells

Direct Methanol Fuel Cells (DMFC's) using polymer electrolyte membranes are promising power sources for portable and vehicular applications. State of the art technology using Nafion(R) 117 membranes (Dupont) are limited by high methanol permeability and cost, resulting in reduced fuel cell efficiencies and impractical commercialization. Therefore, much research in the fuel cell field is focused on the preparation and testing of low crossover and cost efficient polymer electrolyte membranes. The University of Southern California in cooperation with the Jet Propulsion Laboratory is focused on development of such materials. Interpenetrating polymer networks are an effective method used to blend polymer systems without forming chemical links. They provide the ability to modify physical and chemical properties of polymers by optimizing blend compositions. We have developed a novel interpenetrating polymer network based on poly (vinyl - difluoride)/cross-linked polystyrenesulfonic acid polymer composites (PVDF PSSA). Sulfonation of polystyrene accounts for protonic conductivity while the non-polar, PVDF backbone provides structural integrity in addition to methanol rejection. Precursor materials were prepared and analyzed to characterize membrane crystallinity, stability and degree of interpenetration. USC JPL PVDF-PSSA membranes were also characterized to determine methanol permeability, protonic conductivity and sulfur distribution. Membranes were fabricated into membrane electrode assemblies (MEA) and tested for single cell performance. Tests include cell performance over a wide range of temperatures (20 C - 90 C) and cathode conditions (ambient Air/O2). Methanol crossover values are measured in situ using an in-line CO2 analyzer.

Prakash, G. K. Surya↗