Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “oxygen electrode”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

Electrodes for thermionic energy conversion

Problems concerning an application of thermionic energy conversion methods are related to the high heat source temperatures currently required for practical power densities and efficiencies. A description is given of advances made in the development of improved emitter and collector surfaces as a basis for the reduction of operating temperatures. The controlled addition of oxygen has resulted in a considerable improvement of emitter performance. Improvements in converter performance have been obtained by a reduction of the collector work function. Attention is given to fundamental studies, simulated converter environment tests, and variable spacing converter experiments.

Rufeh, F.↗
NASA NTRS2004

Electrochemical Reconstitution of Biomolecules for Applications as Electrocatalysts for the Bionanofuel Cell

Platinum-cored ferritins were synthesized as electrocatalysts by electrochemical biomineralization of immobilized apoferritin with platinum. The platinum cored ferritin was fabricated by exposing the immobilized apoferritin to platinum ions at a reduction potential. On the platinum-cored ferritin, oxygen is reduced to water with four protons and four electrons generated from the anode. The ferritin acts as a nano-scale template, a biocompatible cage, and a separator between the nanoparticles. This results in a smaller catalyst loading of the electrodes for fuel cells or other electrochemical devices. In addition, the catalytic activity of the ferritin-stabilized platinum nanoparticles is enhanced by the large surface area and particle size phenomena. The work presented herein details the immobilization of ferritin with various surface modifications, the electrochemical biomineralization of ferritin with different inorganic cores, and the fabrication of self-assembled 2-D arrays with thiolated ferritin.

Kim, Jae-Woo↗
NASA NTRS2011

Iridium-Doped Ruthenium Oxide Catalyst for Oxygen Evolution

NASA requires a durable and efficient catalyst for the electrolysis of water in a polymer-electrolyte-membrane (PEM) cell. Ruthenium oxide in a slightly reduced form is known to be a very efficient catalyst for the anodic oxidation of water to oxygen, but it degrades rapidly, reducing efficiency. To combat this tendency of ruthenium oxide to change oxidation states, it is combined with iridium, which has a tendency to stabilize ruthenium oxide at oxygen evolution potentials. The novel oxygen evolution catalyst was fabricated under flowing argon in order to allow the iridium to preferentially react with oxygen from the ruthenium oxide, and not oxygen from the environment. Nanoparticulate iridium black and anhydrous ruthenium oxide are weighed out and mixed to 5 18 atomic percent. They are then heat treated at 300 C under flowing argon (in order to create an inert environment) for a minimum of 14 hours. This temperature was chosen because it is approximately the creep temperature of ruthenium oxide, and is below the sintering temperature of both materials. In general, the temperature should always be below the sintering temperature of both materials. The iridium- doped ruthenium oxide catalyst is then fabricated into a PEM-based membrane- electrode assembly (MEA), and then mounted into test cells. The result is an electrolyzer system that can sustain electrolysis at twice the current density, and at the same efficiency as commercial catalysts in the range of 100-200 mA/sq cm. At 200 mA/sq cm, this new system operates at an efficiency of 85 percent, which is 2 percent greater than commercially available catalysts. Testing has shown that this material is as stable as commercially available oxygen evolution catalysts. This means that this new catalyst can be used to regenerate fuel cell systems in space, and as a hydrogen generator on Earth.

Valdez, Thomas I.↗
NASA NTRS1975

Portable automatic blood analyzer

Analyzer employs chemical-sensing electrodes for determination of blood, gas, and ion concentrations. It is rugged, easily serviced, and comparatively simple to operate. System can analyze up to eight parameters and can be modified to measure other blood constituents including nonionic species, such as urea, glucose, and oxygen.

Coleman, R. L.↗
NASA NTRS1992

Effects of the space environment on space-based radar phased-array antenna; status and preliminary observations (LDEF Experiment A0133)

The overall objective of the experiment was to evaluate the effect of the space environment on components considered for a Space-Based Radar (SBR) Phased-Array Antenna. Of primary interest was a study of the degradation of the polyimide film Kapton (DuPont trademark), the material considered for use in the antenna plane. The most striking result of the experiment was the overall good condition of the Kapton antenna planes and Kapton tensile specimens, despite nearly six years of exposure to the space environment. This was largely attributable to the orientation of the Kapton (parallel and flush on the space end) and the stability of the Long Duration Exposure Facility (LDEF) in orbit. However, weathering of exposed Kapton surfaces was not insignificant. Results on elongation and mechanical properties of the plain and the fiberglass-reinforced Kapton are presented. Reduction in strain to failure of flight-exposed Kapton is attributed to surface defects of these specimens. Physical property testing of the materials to date reveals no significant difference between flight-exposed and control material. The second objective was to investigate the interaction between high-voltage electrodes and typical spacecraft contaminants in simulation of discharge triggering across differentially charged dielectric surfaces (spacecraft charging conditions). Electronic data acquisition and memory systems appeared to operate correctly, but very few discharges were recorded. Induced radioactivity, contamination, impacts, and orientation features of atomic oxygen erosion were observed.

J B Whiteside↗
NASA NTRS1977

High efficiency thermionic converter studies

Research in thermionic energy conversion technology is reported. The objectives were to produce converters suitable for use in out of core space reactors, radioisotope generators, and solar satellites. The development of emitter electrodes that operate at low cesium pressure, stable low work function collector electrodes, and more efficient means of space charge neutralization were investigated to improve thermionic converter performance. Potential improvements in collector properties were noted with evaporated thin film barium oxide coatings. Experiments with cesium carbonate suggest this substance may provide optimum combinations of cesium and oxygen for thermionic conversion.

Huffman, F. N.↗
NASA NTRS2010

Development and Testing of High Surface Area Iridium Anodes for Molten Oxide Electrolysis

Processing of lunar regolith into oxygen for habitat and propulsion is needed to support future space missions. Direct electrochemical reduction of molten regolith is an attractive method of processing, because no additional chemical reagents are needed. The electrochemical processing of molten oxides requires high surface area, inert anodes. Such electrodes need to be structurally robust at elevated temperatures (1400-1600 C), be resistant to thermal shock, have good electrical conductivity, be resistant to attack by molten oxide (silicate), be electrochemically stable and support high current density. Iridium with its high melting point, good oxidation resistance, superior high temperature strength and ductility is the most promising candidate for anodes in high temperature electrochemical processes. Several innovative concepts for manufacturing such anodes by electrodeposition of iridium from molten salt electrolyte (EL-Form process) were evaluated. Iridium electrodeposition to form of complex shape components and coating was investigated. Iridium coated graphite, porous iridium structure and solid iridium anodes were fabricated. Testing of electroformed iridium anodes shows no visible degradation. The result of development, manufacturing and testing of high surface, inert iridium anodes will be presented.

Shchetkovskiy, Anatoliy↗
NASA NTRS2010

Development and Testing of High Surface Area Iridium Anodes for Molten Oxide Electrolysis

Processing of lunar regolith into oxygen for habitat and propulsion is needed to support future space missions. Direct electrochemical reduction of molten regolith is an attractive method of processing, because no additional chemical reagents are needed. The electrochemical processing of molten oxides requires high surface area, inert anodes. Such electrodes need to be structurally robust at elevated temperatures (1400-1600?C), be resistant to thermal shock, have good electrical conductivity, be resistant to attack by molten oxide (silicate), be electrochemically stable and support high current density. Iridium with its high melting point, good oxidation resistance, superior high temperature strength and ductility is the most promising candidate for anodes in high temperature electrochemical processes. Several innovative concepts for manufacturing such anodes by electrodeposition of iridium from molten salt electrolyte (EL-Form? process) were evaluated. Iridium electrodeposition to form of complex shape components and coating was investigated. Iridium coated graphite, porous iridium structure and solid iridium anodes were fabricated. Testing of electroformed iridium anodes shows no visible degradation. The result of development, manufacturing and testing of high surface, inert iridium anodes will be presented.

Shchetkovskiy, Anatoliy↗
NASA NTRS1991

Oxygen and iron production by electrolytic smelting of lunar soil

Oxygen, present in abundance in nearly all lunar materials, can theoretically be extracted by molten silicate electrolysis from any known lunar rock. Derivation of oxygen by this method has been amply demonstrated experimentally in silicate melts of a variety of compositions. This work can be divided into three categories: (1) measurement of solubilities of metals (atomic) in silicate melts; (2) electrolysis experiments under various conditions of temperature, container material, electrode configuration, current density, melt composition, and sample mass (100 to 2000 mg) measuring energy required and character of resulting products; and (3) theoretical assessment of compositional requirements for steady state operations of an electrolysis cell.

Colson, R. O.↗
NASA NTRS1978

Water electrolysis system - H2 and O2 generation

An oxygen generation system design based on the static feed water electrolysis concept is described. The system is designed to generate 4.20 kg/d of oxygen to satisfy the metabolic needs of a three-person crew, to compensate for spacecraft leakage, and to provide the oxygen required by the electrochemical depolarized CO2 concentrator. The system has a fixed hardware weight of 75 kg, occupies a volume of 0.11 cu m, and requires only 1.1 kw of electrical power. The static feed electrolysis concept is discussed, and experimental data on the high-performance electrode are presented.

Schubert, F. H.↗
NASA NTRS2011

Amperometric Solid Electrolyte Oxygen Microsensors with Easy Batch Fabrication

An amperometric solid electrolyte oxygen (O2) microsensor using a novel and robust structure has been developed with a detection range of 0.025 to 21 percent of O2 concentration. The microsensor has a simple structure with a sensing area of 1.10 0.99 mm(exp 2), and is operated by applying voltage across the electrodes and measuring the resulting current flow at a temperature of 600 C.

Hunter, Gary W.↗
NASA NTRSDate not supplied

Suborbital Lunar Gravity Experiment of an Electrodynamic Regolith Conveyor

NASA’s Swamp Works Electrostatics and Surface Physics Laboratory (ESPL) is planning to test a 4-phase electrodynamic regolith conveyor in simulated lunar gravity on a suborbital flight in 2023. A 4-phase electrodynamic regolith conveyor could convey regolith without the risk of rotating or vibratory actuation, which could jam or require regular maintenance due to the abrasive nature of lunar regolith. Another advantage of electrodynamic conveying is the reduction of conveying power, which is important considering the limited scale of available early-stage lunar power systems. The current state of the art(SOA) for lunar regolith conveying is based on recent NASA system studies for oxygen production plants. These plant designs require conveying rates around 100 kg/hr, to produce 10 mT/yr of oxygen from the regolith. To accomplish this, conventional augers and vibratory spiral conveyors have been identified as the SOA or the leading candidates due to their extensive use in the terrestrial material handling industry. At NASA KSC, the use of dynamic electric fields, generated by alternating high voltage on electrodes, has been developed as a dust mitigation solution known as the Electrodynamic Dust Shield (EDS). The EDS is being developed for lenses, solar panels, radiators, fabric and seals. ESPL researchers have shown the ability to move thin layers (~ a few mm) of dust with mW of power. In Academia, researchers have shown the ability to electrodynamically convey regolith up to ~1 kg/hr with a4-phase EDS and electromagnetically convey particles that would suggest a lunar regolith conveying rate of ~25 kg/hr. This paper will describe the design and expected operation of a 4-phase electrodynamic regolith conveyor in lunar gravity. This paper will also describe how an electrodynamic conveyor could be scaled for transporting ISRU relevant flow rates.

Aaron D S Olson↗
NASA NTRSDate not supplied

Design and Testing of a Prototype Electrodynamic Regolith Conveyor for Lunar ISRU

NASA’s Swamp Works Electrostatics and Surface Physics Laboratory (ESPL) is developing a 4-phaseelectrodynamic regolith conveyor (ERC) that could convey regolith without the risk of rotating or vibratory actuation, which could jam or require regular maintenance due to the abrasive nature of lunar regolith. Another goal of electrodynamic conveying is the reduction of conveying power, which is important considering the limited capacity of early-stage lunar power systems. The current state of the art(SOA) for lunar regolith conveying is based on recent NASA system studies for oxygen production plants. These plant designs require conveying rates around 100 kg/hr, to produce 10 mT/yr of oxygen from the regolith. To accomplish this, conventional augers and vibratory spiral conveyors have been identified as the SOA or the leading candidates due to their extensive use in the terrestrial material handling industry. At NASA KSC, the use of dynamic electric fields, generated by alternating high voltage on electrodes, has been developed as a dust mitigation solution known as the Electrodynamic Dust Shield (EDS). The EDS is being developed for lenses, solar panels, radiators, fabric and seals and is scheduled for a technology demonstration mission on the Moon in 2023. ESPL researchers have shown the ability to move thin layers (~ a few mm) of dust with mW of power. In Academia, researchers have shown the ability to electrodynamically convey regolith up to ~1 kg/hr with a 4-phase EDS and electromagnetically convey particles that would suggest a lunar regolith conveying rate of ~25 kg/hr. This paper will describe the design and testing of a prototype ERC that could scale to support transporting regolith at ISRU relevant flow rates.

Aaron D S Olson↗
NASA NTRSDate not supplied

Design and Testing of a Prototype Electrodynamic Regolith Conveyor For Lunar ISRU

NASA’s Kennedy Space Center’s (KSC) Swamp Works Electrostatics and Surface Physics Laboratory (ESPL) is developing a 4-phase Electrodynamic Regolith Conveyor (ERC) that could convey regolith without the risk of rotating or vibratory actuation, which could jam or require regular maintenance due to the abrasive nature of lunar regolith. Another goal of electrodynamic conveying is the reduction of conveying power, which is important considering the limited capacity of early-stage lunar power systems. The current state of the art (SOA) for lunar regolith conveying is based on recent NASA system studies for oxygen production plants. These plant designs require conveying rates around 100 kg/hr, to produce 10 mT/yr of oxygen from the regolith. To accomplish this, conventional augers and vibratory spiral conveyors have been identified as the SOA or the leading candidates due to their extensive use in the terrestrial material handling industry. At NASA KSC, the use of dynamic electric fields, generated by alternating high voltage on electrodes, has been developed as a dust mitigation solution known as the Electrodynamic Dust Shield (EDS). The EDS is being developed for lenses, solar panels, radiators, fabric and seals and is scheduled for a technology demonstration mission on the Moon in 2023. ESPL researchers have shown the ability to move thin layers (a few mm) of dust with mW of power. In Academia, researchers have shown the ability to electrodynamically convey regolith up to 1 kg/hr with a 4-phase EDS. This paper will describe the design and testing of a prototype ERC that could scale to support transporting regolith at ISRU relevant flow rates.

Conveyor↗
NASA NTRSDate not supplied

Design and Testing of a Prototype Electrodynamic Regolith Conveyor for Lunar ISRU

NASA’s Kennedy Space Center’s (KSC) Swamp Works Electrostatics and Surface Physics Laboratory (ESPL) is developing a 4-phase Electrodynamic Regolith Conveyor (ERC) that could convey regolith without the risk of rotating or vibratory actuation, which could jam or require regular maintenance due to the abrasive nature of lunar regolith. Another goal of electrodynamic conveying is the reduction of conveying power, which is important considering the limited capacity of early-stage lunar power systems. The current state of the art (SOA) for lunar regolith conveying is based on recent NASA system studies for oxygen production plants. These plant designs require conveying rates around 100 kg/hr, to produce 10 mT/yr of oxygen from the regolith. To accomplish this, conventional augers and vibratory spiral conveyors have been identified as the SOA or the leading candidates due to their extensive use in the terrestrial material handling industry. At NASA KSC, the use of dynamic electric fields, generated by alternating high voltage on electrodes, has been developed as a dust mitigation solution known as the Electrodynamic Dust Shield (EDS). The EDS is being developed for lenses, solar panels, radiators, fabric and seals and is scheduled for a technology demonstration mission on the Moon in 2023. ESPL researchers have shown the ability to move thin layers (a few mm) of dust with mW of power. In Academia, researchers have shown the ability to electrodynamically convey regolith up to 1 kg/hr with a 4-phase EDS. This paper will describe the design and testing of a prototype ERC that could scale to support transporting regolith at ISRU relevant flow rates.

Lunar↗
NASA NTRS1984

Preparation and evaluation of advanced catalysts for phosphoric acid fuel cells

The platinum electrocatalysts were characterized for their crystallite sizes and the degree of dispersion on the carbon supports. One application of these electrocatalysts was for anodic oxidation of hydrogen in hot phosphoric acid fuel cells, coupled with the influence of low concentrations of carbon monoxide in the fuel gas stream. In a similar way, these platinum on carbon electrocatalysts were evaluated for oxygen reduction in hot phosphoric acid. Binary noble metal alloys were prepared for anodic oxidation of hydrogen and noble metal-refractory metal mixtures were prepared for oxygen reduction. An exemplar alloy of platinum and palladium (50/50 atom %) was discovered for anodic oxidation of hydrogen in the presence of carbon monoxide, and patent disclosures were submitted. For the cathode, platinum-vanadium alloys were prepared showing improved performance over pure platinum. Preliminary experiments on electrocatalyst utilization in electrode structures showed low utilization of the noble metal when the electrocatalyst loading exceeded one weight percent on the carbon.

Stonehart, P.↗
NASA NTRS1985

Textured carbon on copper: A novel surface with extremely low secondary electron emission characteristics

Experimentally determined values of true secondary electron emission and relative values of reflected primary electron yield for a range of primary electron beam energies and beam impingement angles are presented for a series of novel textured carbon surfaces on copper substrates. (All copper surfaces used in this study were oxygen-free, high-conductivity grade). The purpose of this investigation is to provide information necessary to develop high-efficiency multistage depressed collectors (MDC's) for microwave amplifier traveling-wave tubes (TWT's) for communications and aircraft applications. To attain the highest TWT signal quality and overall efficiency, the MDC electrode surface must have low secondary electron emission characteristics. While copper is the material most commonly used for MDC electrodes, it exhibits relatively high levels of secondary electron emission unless its surface is treated for emission control. The textured carbon surface on copper substrate described in this report is a particularly promising candidate for the MDC electrode application. Samples of textured carbon surfaces on copper substrates typical of three different levels of treatment are prepared and tested for this study. The materials are tested at primary electron beam energies of 200 to 2000 eV and at direct (0 deg) to near-grazing (85 deg) beam impingement angles. True secondary electron emission and relative reflected primary electron yield characteristics of the textured surfaces are compared with each other and with those of untreated copper. All the textured carbon surfaces on copper substrate tested exhibited sharply lower secondary electron emission characteristics than those of an untreated copper surface.

Curren, A. N.↗
NASA NTRS1993

Ceramic distribution members for solid state electrolyte cells and method of producing

A solid state electrolyte cells apparatus and method of producing is disclosed. The apparatus can be used for separating oxygen from an oxygen-containing feedstock or as a fuel cell for reacting fluids. Cells can be stacked so that fluids can be introduced and removed from the apparatus through ceramic distribution members having ports designed for distributing the fluids in parallel flow to and from each cell. The distribution members can also serve as electrodes to membranes or as membrane members between electrodes. The distribution member design does not contain any horizontal internal ports which allows the member to be thin. A method of tape casting in combination with an embossing method allows intricate radial ribs and bosses to be formed on each distribution member. The bosses serve as seals for the ports and allow the distribution members to be made without any horizontal internal ports.

Clark, Douglas J.↗