SEARCH · Engineering Papers
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.
Pretreatment of urine prevents micro-organism growth in boiler and kills micro-organisms in condenser. Chemicals also clean evaporation surface, fix ammonia in boiling chamber, and suppress foaming.
Investigations were completed on wash waters based on each candidate personal cleansing agent. Evaluations of coagulants, antifoam agents, and the effect of promising antifoams on the chemical precipitation were included. Based on these evaluations two candidate soaps as well as their companion antifoam agents were selected for further work. Operating parameters included the effect of soap concentration, ferric chloride concentration, duration of mixing, and pore size of depth filters on the degree of soap removal. The effect of pressure on water flow through filter cartridges and on the rate of decline of water flow was also investigated. The culmination of the program was the recommendation of a pretreatment concept based on chemical precipitation followed by pressure filtration.
The effluent gas stream from an electrolytic urine pretreatment process was analyzed by gas chromatography-mass spectroscopy and wet chemical methods to determine its composition. The major constituents were identified as: hydrogen, carbon dioxide, oxygen, nitrogen, water vapor, and chlorine. The trace impurities were chlorinated light hydrocarbons, and a number of other organic impurities in the low ppm range. Several methods of removing all of the undesirable gases to levels acceptable for return to a space cabin atmosphere were investigated experimentally. A subsystem concept comprised of the following sequential unit processes and operations was successfully demonstrated: (1) raw urine scrubbing, (2) silica gel sorption, (3) dilution with cabin air, and (4) catalytic oxidation.
An experimental effort has been undertaken to examine the effect of plasma pretreatment of various substrate materials coated with a polymer in the parylene family. This report describes the procedure and discusses initial data which indicate using plasmas of argon and oxygen to promote adhesion of parylene coatings upon many difficult-to-bond substrates. Substrates investigated were gold, nickel, kovar, teflon (FEP), kapton, silicon, tantalum, titanium, and tungsten. Without plasma treatment, 180 deg peel tests yield a few g/cm (oz/in) strengths. With dc plasma treatment in the deposition chamber, followed by coating, peel strengths are increased by one to two orders of magnitude.
Addition of CO to He pretreatment doubles catalytic activity. In sealed, high-energy, pulsed CO2 laser, CO and O2 form as decomposition products of CO2 in laser discharge zone. Products must be recombined, because oxygen concentration of more than few tenths of percent causes rapid deterioration of power, ending in unstable operation. Promising low-temperature catalyst for combining CO and O2 is platinum on tin oxide. New development increases activity of catalyst so less needed for recombination process.
Aramid-reinforced composite materials of equal fiber volume and varied polymer thermoset matrices were pultruded and flexurally tested to failure. The objective was to improve the flexural properties of aramid-reinforced pultrusions. Pultrusions of both sized and unsized aramid fiber with four different resin systems were compared to determine the effects of sizing compounds and postcuring on flexural strength, fiber wettability, and fiber-to-resin interface bonding. Improvements in flexural strength resulting from pretreatments with the sizing solutions used were marginal. The most significant improvements in flexural properties resulted from postcuring. Flexural strengths ranged from a low of 39,647 psi (273MPa) to a high of 80,390 psi (554 MPa), an overall increase of 103 percent. The fact that postcuring improved the flexural properties of the pultrusions of the four resin systems indicates that a full cure did not occur in any of the resin systems during the pultrusion process. The increased flexural strengths of the polyester and vinyl ester pultrusions were the most surprising. The four resin systems examined were Interplastic Corporation VE 8300 vinyl ester, Ashland Chemical Company Aropol 7430 Polyester, and Shell Chemical Company Epon 9302 and Epon 9310 epoxides.
Aramid reinforcement composite materials of equal fiber volume having varied polymer thermoset matrices have been pultruded and flexurally tested to failure. The objective was to improve flexural properties of aramid reinforced pultrusions. Pultrusions of both sized and unsized aramid fiber with four different resin systems were compared to determine the effects of sizing compounds and post-thermal treatments on the flexural strength as an indication of fiber wettability and fiber-to-resin interface bonding. Improvements in flexural strength as the result of pretreatments with sizing solutions used in this study were marginal. The most significant improvements in flexural properties were the results of postcuring. Overall improvements ranged from a low 39,647 Psi(273 Mpa) to a high of 80,390 Psi(554 Mpa), or 103 percent. The fact that post-thermal treatments improved the flexural properties of the four pultrusions indicates that a full cure did not occur in either resin system during the pultrusion process. The increased flexural strengths of the polyester and vinyl ester pultrusions were the most surprising. Based on data presented, the most promising resin system of the four examined (VE 8300, Aropol 7430, Epon 9302, and Epon 9310) for Kevlar reinforced pultrusion is Epon 9310 epoxy.
A commercial platinized tin oxide catalyst used for low-temperature CO oxidation has been characterized using ion scattering spectroscopy (ISS), Auger electron spectroscopy (AES) and Electron Spectroscopy for Chemical Analysis (ESCA) before and after reduction in 40 Torr of CO for 1 hour at various temperatures from 75 to 175 C. The reduction results in loss of surface oxygen, formation of metallic tin, conversion of platinum oxides to Pt-O-Sn and Pt(OH)2 and a small amount of metallic Pt which alloys with the tin. These results should be useful in understanding how the pretreatment temperature affects the catalytic activity of platinized tin oxide toward CO oxidation.
The solid rocket booster (SRB) has historically used a chromate conversion coating prior to protective finish application. After conversion coating, an organic paint system consisting of a chromated epoxy primer and polyurethane topcoat is applied. An overall systems approach was selected to reduce waste generation from the coatings application and removal processes. While the most obvious waste reduction opportunity involved elimination of the chromate conversion coating, several other coating system configurations were explored in an attempt to reduce the total waste. This paper will briefly discuss the use of a systems view to reduce waste generation from the coating process and present the results of the qualification testing of nonchromated aluminum pretreatments and alternate coating systems configurations.
Cellulose in inedible plant materials, forestry residues, and municipal wastes must be pretreated to disrupt its physical structure, thereby making its hydrolysis to glucose practical. Developments since 1991 are summarized.
Nutrient recovery has always been a problem for long distance and long-term space missions. To allow humans to man these missions, a steady source of oxygen, water, and food are necessary for survival beyond Earth's atmosphere. Plants are currently an area of interest since they are capable of providing all three resources for life sustainability. We are currently interested in nutrient recovery for future plant growth and simple aqueous leachate extractions can recover some of the nutrients. However, leaching plants also removes water-soluble organic plant wastes, which inhibits plant growth if not separated properly. To combat the issues with waste and maximize nutrient recovery, we are attempting to pre-treat the plant matter using biological, thermal, and photocatalytic methods before subjecting the solution with variable-strength acid digestion. For the biological method, the inoculums: mixed heterotrophic/nitrifying bioreactor effluent and Trichoderma vessei are used in an attempt to liberate more nutrients from the plant matter. For the thermal method, plants are subjected to varying temperatures at different retention times to determine nutrient recovery. Lastly, the photocatalytic method utilizes TiO (sub 2)'s oxidizing abilities under specific pHs and retention times to reduce organic wastes and improve nutrient gains. A final acid digestion serves to liberate nutrients even further in order to maximize recovery. So far, we have tested ideal acid digestion variables for practicality and performance in our experiments. We found that a low retention time of 10 minutes and a high acid concentration of 0.1 and 1 mole HCl were the most effective at nutrient recovery. For space travel purposes, 0.1 mole currently looks like a viable acid digestion to use since it is relatively effective and sustainable from a mass and energy balance if acid recovery can be performed on waste brines. Biological pretreatments do not look to be too effective and the thermal and photocatalytic methods may be preferred since they show a potential to recover more than 70 percent of the nutrients.
The Planetary Urine Processor (PUP) is a urine distillation system for lunar or planetary applications, taking advantage of local gravity for phase separation as well as the movement and storage of waste feeds and distillate. The PUP utilizes a stationary evaporator with an integrated disposable bag to process urine and capture remaining precipitates. This system aims to increase water reclamation percentage to greater than 96%, reduce resource requirements, and enhance reliability and maintainability due to lower system complexity over the existing water recovery system on the International Space Station (ISS). This paper focuses on the hardware development, testing efforts, and the associated urine pretreatment development work.
The Planetary Urine Processor (PUP) is a urine distillation system for lunar or planetary applications, taking advantage of local gravity for phase separation as well as the movement and storage of waste feeds and distillate. The PUP utilizes a stationary evaporator with an integrated disposable bag to process urine and capture remaining precipitates. This system aims to increase water reclamation percentage to greater than 96%, reduce resource requirements, and enhance reliability and maintainability due to lower system complexity over the existing water recovery system on the International Space Station (ISS). This paper focuses on the hardware development, testing efforts, and the associated urine pretreatment development work.
A homogeneous catalyst is provided comprising one or more metals; and at least two metal coordinating ligands wherein the homogeneous catalyst is a multi-ligand metal complex adapted for use with an oxidant in an oxidation reaction to catalytically pretreat lignocellulosic biomass. In one embodiment, the homogenous catalyst is copper (II) 2, 2′ bipyridine ethylenediamine (Cu(bpy)en). Related methods are also disclosed.
An engineering-scale electrochemical processing skid is proposed to perform the denitration of Hanford tank waste, which would help to mitigate a key process concern with the direct feed processing of the Hanford Tank Waste Treatment and Immobilization Plant (WTP). The reduction of nitrates and organic compounds in the waste feed will directly reduce hazardous NOx and ammonia gases generated during the vitrification process, which in turn will aid in addressing potential regulatory and safety challenges associated with processing large volumes of tank waste. This paper highlights the past legacy work, project layout, accomplishments from Phase 1 and research and development envisioned for Phase 2. An innovative electrochemical denitration and caustic generation (EDCGe) process was demonstrated for the pretreatment of tank waste at the Savannah River Site (SRS) in the early 2000s. The denitration electrolyzer, off-gas abatement system, and caustic generator electrolyzer are being developed with the intent that the denitration electrolyzer will convert nitrate and nitrite anions to nitrogen gas while also yielding other gaseous byproducts, which may include N2O, NH3, VOCs, and H2. The gaseous byproducts will be managed via a tandem off-gas catalyst-bed treatment system. The caustic generation electrolyzer will recycle NaOH from the feed to produce a clean caustic stream for use within the batching tanks at Hanford, aiding in the preparation of waste for WTP. The reduction in hazardous emissions and improved waste treatment processes provides a robust solution for nuclear waste management, contributing to environmental safety and regulatory compliance. The EDCGe technology is being adapted, modified, and updated for the preparation of the Direct Feed-High Level Waste (DF-HLW) flowsheet at Hanford. Phase 1 demonstrated a bench-scale proof-of-concept for reactions involving the denitration electrolyzer and gas phase abatement of ammonia. The electrochemical technology is drawing on the scientific outcomes that were reported in the legacy work. The results from Phase 1 demonstrated the viability of the EDCGe system in reducing the nitrogen species of simple non-radioactive waste simulants. Commercially available alloys used as electrode materials and membranes are being studied for the denitration and caustic generation electrolyzers. The continuation of this project holds promise for broader applications, such as energy-efficient ammonia production, and contributes significant advancements in nuclear waste management. Additional material discovery has been investigated into ceramic Na super ion conductive (NaSICON) materials and off-gas abatement catalyst discovery. NaSICON is of interest for selective transport of Na within the electrolyzers to make a clean caustic stream. Future integration and optimization efforts, informed by Phase 1 results and ongoing research, will continue to drive advancements in nuclear waste management technology. The technology developed for the EDCGe treatment of tank waste will also have broader potential to inform other fields, such as energy-efficient ammonia production, as well as ammonia abatement catalysis through the lessons learned in electrochemical nitrate reduction. The applications and benefits of this research extend beyond Hanford and the Savannah River Site, supported by a collaborative team of scientists and engineers from national labs, academia, and industry, ensuring a comprehensive approach to solving complex waste treatment challenges. The team is leveraging advanced electrochemical technologies, machine learning, novel catalysts tailored for gaseous nitrogen species, and cutting-edge reactor systems to enhance the process efficiency and effectiveness of the denitration process.
Lithium (Li)-oxygen (O2) batteries (LOBs) exhibit the highest theoretical specific energy density among candidates of the next-generation energy storage systems, but the instability of Li metal anode (LMA), air electrode, and electrolyte largely limit the practical energy density of these batteries. Herein, we report an effective method to protect LMA against side reactions between LMA and crossover contaminants such as highly reactive oxygen moieties. A solid electrolyte interphase (SEI) layer rich in inorganic components was formed on a LMA coated with polyethylene oxide thin-film through an in-situ electrochemical pre-charging step under oxygen atmosphere. This uniformly distributed stiff SEI layer interacted with flexible polymer matrix and formed a submicron-sized gel-like polymer layer. This polymer supported SEI layer leads to much longer cycle life (130 vs. 65 cycles) as compared to those of pristine cell under the same testing conditions (1.0 mAh cm-2 at 0.2 mA cm-2 in the voltage range of 2 to 5 V without any catalysts). It is also very effective during low voltage (2 to 4.5 V) cycling with a redox mediator (0.1 and 0.15M (2,2,6,6-tetramethylpiperidin-1-yl) oxidanyl). Therefore, this approach can be used to stabilize LMA/electrolytes interphase and improve the cycle life of rechargeable LOBs.
The strong tendency of lignin to aggregate in solution, coupled with limited understanding of how its molecular structure governs this behavior, hinders its effective utilization in biorefineries. Here, in this study, we investigated the solution behavior of lignin extracted from poplar using γ-valerolactone/water (GVL/H2O, 9:1 wt/wt) through combined small-angle neutron scattering (SANS) and molecular dynamics (MD) simulations. Lignin samples obtained at 100 °C (L100) and 120 °C (L120) differed in β–O–4 content, hydroxyl distribution, and S/G ratio, enabling direct assessment of how molecular composition governs solvation and aggregation. SANS showed that L120 formed rigid and elongated cylindrical aggregates at 25 °C that transitioned to more flexible spheroidal structures by 50 °C and remained stable up to 80 °C, whereas L100 adopted globular aggregates that progressively collapsed with increasing temperature. MD simulations reinforced these observations by showing that S-rich (L120-like) oligomers had larger radii of gyration, stronger solvent coordination driven by methoxy groups, and fewer lignin–lignin contacts. In contrast, G-rich (L100-like) oligomers displayed persistent aggregation and lower solubility. Collectively, these results reveal that increased aromatic methoxylation enhances lignin–solvent interactions and suppresses self-association, whereas reduced methoxylation and higher β–O–4 content promote persistent aggregation into colloid-like structures with restricted solvent penetration into the aggregate interior.