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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.

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139 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS2019

Numerical Model of the Mars Electrostatic Precipitator

NASA's future human exploration missions will require chemical processing plants to convert local resources into consumables to support astronaut activities. The thin and mostly carbon dioxide atmosphere of Mars is estimated to have 1 - 10 particles/cu.cm with diameters of 1 - 10 m and up to 1000 particles/cu.cm during storms. The dust in the Martian atmosphere can foul chemical reactors and pose a risk to life support systems. Electrostatic precipitation (ESP) removes dust particles from the Martian atmosphere. The Electrostatics and Surface Physics Laboratory at NASA's Kennedy Space Center has developed a COMSOL Multiphysics(Registered Trademark) model of an ESP for dust filtration on Mars. The fundamental principles of an ESP can be simulated by four physics modules: plasma, AC/DC electromagnetics, computational fluid dynamics (CFD), and particle tracing. In the ESP model presented here, the plasma module was solved to estimate particle charge. The AC/DC and CFD module were solved for the electrostatic force and fluid force. The particle-tracing module was solved for particle collection efficiency.

Wang, Jerry J.↗
NASA NTRS2015

Space Technology Game Changing Development: Synthetic Biological Membrane

The goal of this project is to use synthetic biology techniques to develop biomimetic FO membranes that can self-repair when exposed to chemical and physical damage, as well as radiation and fouling. The self-repair capability is derived from the regenerative characteristics of living systems. Ultimately, this living membrane will be used to extend the operating life and improve the performance of membrane-based life support systems currently being used by NASA.Biological membranes are primarily composed of lipid bilayers. Lipids are organic compounds that, due to their polar hydrophobic fatty acid tails per lipid molecule, are able to self-assemble spontaneously. The lipid bilayer acts as a selective barrier, letting only specific molecules cross the membrane. Recent research into membranes for Next Generation Life Support (NGLS) applications has identified a type of FO membrane that can function as a biomimetic structure.

Flynn, Michael↗
NASA NTRS2020

An Update on NASA's Lunar Dust Mitigation Strategy

It is well known that the Apollo lu-nar surface missions experienced a number of issues related to dust – which are sometimes referred to as “The Dust Problem”. The jagged, electrostatically charged lunar dust particles can foul mechanisms and alter thermal properties. They tend to abrade textiles and scratch surfaces. NASA and other interested par-ties require an integrated, end-to-end dust mitigation strategy to enable sustainable lunar architectures.

Johansen, M. R.↗
NASA NTRS2019

Improving Tracer Particle Surface Properties for Wind Tunnel Research

The surface properties of micron size polystyrene latex microspheres (PSLs) modified with quaternary alkylammonium (QA) surfactants were investigated, with a focus on the relationship between surface chemistry and adhesion. These investigations were motivated by the need to develop non-fouling tracer particles for wind tunnel studies. The goals were to relate the work of adhesion between particles and substrates to the type and amount of QA modifier in order to optimize the performance of PSL tracers. Surfactant-free emulsion polymerization (SFEP) can produce PSLs for wind tunnel tracers. Covalentlybound charged groups (derived from the initiator) stabilize PSL surfaces in water. This work used PSLs with anionic surface groups. Previous studies indicated that surface-bound charged groups on PSLs have a significant impact on their interfacial energy. Modifying charged surface groups therefore offers a method to modulate PSL interfacial properties. In this work, PSLs and films were modified by adsorption of QA surfactants.

Schmitz, Russell C.↗
NASA NTRS2011

TPSAS-NF1676L-12159-DND

Flight tests have demonstrated that in many operational environments, insect residue buildup on the leading edge of an aircraft wing can cause the loss of laminar flow. The airborne insect threat occurs between ground level and 152.4 m with the highest population concentration occurring during light winds (2.6 – 5.1 m/s), high humidity, and temperatures between 21-29°C. Under these conditions, mitigation is needed during takeoff, initial climb, approach, and landing. When insect fouling reaches a critical height, laminar flow is disrupted leading to increased drag and hence additional fuel consumption for the duration of the flight. This critical height is highly dependent upon the airfoil and Reynold’s number. Several techniques (e.g. paper, scrapers, surfactants, flexible surfaces, etc.) investigated to date have the potential to mitigate this problem; however, implementation has proven to be impractical thus limiting their utility. For example, the Kreuger flap (illustrated above) has been shown to negate insect excrescence from the wing leading edge while also improving lift during takeoff. However its complexity and physical discontinuities may induce early boundary layer transition on the lower surface.

T M Lorenzi↗
NASA NTRSDate not supplied

Supercritical Water Oxidation (SCWO) for the treatment of spacecraft waste.

Supercritical water oxidation (SCWO) is a powerful waste treatment that has been considered as a substitute or complement to other potential spacecraft waste handling methods including jettisoning, compacted sealed storage, drying, and others. Combustible trash and garbage is mixed with water and then heated and pressurized above the critical point of water (705 °F and 218 atmospheres). The waste is nearly all oxidized to produce carbon dioxide, water and nitrogen. NOx is not formed. The combustion energy can be used to heat the input stream. SCWO is relatively complex, expensive, and hazardous compared to other methods. Oxidation of compounds containing chlorine and sulfur produces hydrochloric and sulfuric acid which can cause corrosion in the reactor. Neutralizing these acids produces salts which can precipitate and cause clogging. The major engineering challenges to implementing SCWO are chemical corrosion and fouling due to the deposition of salts. SCWO was first proposed for general waste treatment and for spacecraft in the 1980’s and extensive research has been carried out.

Harry W Jones↗
NASA NTRS2021

Supercritical Water Oxidation (SCWO) Trade Study and 2021 Final Report

SCWO is a promising technology whose main benefits is that it is capable of completely mineralizing organic compounds in wastewater and separating inorganic salts. This means that SCWO can theoretically function as a single step water treatment system. It performs the functions of both the primary treatment system and the secondary brine drying function to achieve near 100% water recovery. It can also handle solids so no pretreatment of the feed is required. A preliminary trade study indicates that SCWO could be competitive with the ISS state of the art if its power consumption could be reduced. Thermal and mechanical energy recovery system exist that could reduce SCWO energy consumption to a level that is competitive with the state of the art. In addition, increasing the feed wastewaters organic content by including other wastes, such as feces, could produce a reactor that is thermally self-sustaining. There are 5 different types of SCWO reactors. They are; tubular, tank, impingement, transpiring wall reactors (TWR) and super critical water mixing (SCWM) reactors. Of these the best suited for NASA missions are the impingement and SCWM reactors. The impingement reactor is best suited for near term missions because it can treat the low organic content wastewaters such as are expected for initial Lunar and Mars missions and has the ability to remove precipitated inorganic solids. The SCWM reactor is best suited for longer duration CELSS type missions where high organic content wastewater is available and will resolve solids fouling and corrosion issues. In addition, these two reactors have a long NASA heritage and have been developed specifically for space flight application. Tubular reactors suffer from plugging issues which is a safety concern. Tank reactors will increase in size inversely with gravity, which will trade poorly in Lunar and Mars environments where gravity is reduced. TWR reactors require high organic content wastewater feed and the SCWM reactor is an optimized version of the TWR for NASA applications. It is recommended that in FY 2022 NASA continue to fully evaluate the ability of SCWO to produce potable water and remove inorganics as a solid byproduct. This should be done using the impingement reactor for near term missions and SCWM for longer duration missions. NASA should also develop optimized recuperative heat exchangers and pressure recovery devices to reduce power consumption and investigate inclusion of feces and other organic wastes into the wastewater model to increase its organic content and further reduce thermal energy requirements.

Supercritical Water Oxidation↗
NASA NTRSDate not supplied

Monitoring of Ionic Silver Biocide with Capacitively-Coupled Contactless Conductivity Detection (C4D)

Monitoring of biocide dosing in spacecraft potable water systems is desirable to ensure dosing system operation and resultant microbial control. Electrolytic conductivity is linearly related to the concentration ionic silver (Ag+, the baseline biocide for future NASA missions) chemically dosed into highly purified water, and could serve as a proxy measurement. Traditional conductivity cells rely on immersed metal or graphite electrodes, which may potentially be subject to significant current-induced or auto-galvanic deposition of Ag+. Furthermore, oxide fouling may potentially induce measurement errors. Capacitively-coupled contactless conductivity detection (C4D) is a promising alternative. C4D uses electrodes placed outside an inert, non-conductive flow path, potentially mitigating such problems. We identified and purchased a commercial C4D system with claimed performance (conductivity range: 20 nS/cm to 4 µS/cm) appropriate for this application. We characterized the instrument’s performance with conductivity standards and Ag+ solutions. We began investigations considering practical and long-term detector operation, including potential current-induced deposition of conductive deposits at the tubing wall. In addition, we designed a side-stream flow system to provide liquid flow through the narrow tubing (1/16” outer diameter) required by the detector and characterized the performance of the combined C4D detector/flow system. Finally, we completed theoretical modeling of expected conductivity change with multiple dosing techniques and water chemistries.

Lance Dean Delzeit↗
NASA NTRS2022

Ultra-Pure, High Endurance Liquid Bladder with Volume Sensor for Space Applications

The NASA Portable Life Support System (PLSS) for the Exploration Extravehicular Mobility Unit (xEMU) incorporates a Feedwater Supply Assembly (FSA) to store consumable cooling water. The FSA accepts pure water prior to each Extra-Vehicular Activity (EVA), then supplies this water to a membrane evaporator at ambient suit pressure during the eight hour EVA. The FSA must function reliably for hundreds of EVAs over 15 years of service without introducing contamination that may accumulate and foul the membrane. We present a unique design that combines the benefits of a flexible fluoropolymer bladder with the strength and convenience of a rigid tank, providing an ultra-pure, ambient-pressure reservoir with fill-drain cycle life exceeding 3000, internal pressure tolerance exceeding 100 psi, high volumetric efficiency, near-zero dead volume, optical transparency for visual inspection, simplified mounting, and very low mass. We also incorporate a novel volume sensor suitable for both microgravity and arbitrarily accelerated environments and capable of real-time monitoring with accuracy on the order of 2.5% full scale. Analytical predictions are supported by experimental test data from a mature subscale prototype.

PLSS Portable Life Support System FSA Feedwater Su↗
NASA NTRS2022

Water Quality Contamination Sources and Controls for the Exploration Extra-vehicular Mobility Unit (xEMU)

NASA has been developing a new spacesuit, called the Exploration Extravehicular Mobility Unit (xEMU) for over a decade. This spacesuit is underdevelopment to support missions to the International Space Station (ISS) and also to the Moon. The xEMU uses controlled evaporative cooling through a membrane to reject waste heat from the crewmember, avionics, and environmental in-leak during autonomous operation. Given the unique mass and volume constraints imposed by the spacesuit application and the opportunities presented by the selection of a given membrane, the xEMU does not possess a separate feedwater loop to feed the evaporation process, rather the feedwater for the evaporation process is fed directly from the transport loop which collects heat from the sources within the suit. This has many benefits including mass/volume reductions from a lower component count within the system but does pose some additional potential constraints on water quality within the system in order to provide a working fluid that can be pumped, filtered, and used in contact with the remainder of the system while both avoiding fouling of the membrane as well as other deleterious effects such as creating conditions for corrosion of wetted surfaces within the transport loop. The discussion will seek to address the main sources of contamination and the applied controls. Sources considered will include: self-generated via materials selection and processes applied, influent working fluid, contamination of the influent working fluid via Ground Support Equipment (GSE) or processing equipment, microbial activity, and environmental influences such as elevated ambient CO2.

Colin Campbell↗
NASA NTRS2022

Repeatable Method for Conducting Chamber Studies of Aerosolized Lunar Simulant

The Artemis Mission goal of returning humans to the Moon requires new solutions to engineering problems posed by the extremely harsh environment of the lunar surface. Using the Apollo missions as historical evidence, dust will be a significant obstacle in the success of a sustained human and robotic presence. Hardware such as tools, machinery, extra-vehicular activity (EVA) suits, and components of landers and habitats will all be subject to various degrees of contamination by lunar dust, and each piece of hardware has its own considerations for performance under dusty conditions. Such hardware must be tested and verified for use during lunar missions under guidance from NASA technical standards. Aerosolized dust can be used to test and verify hardware in two ways: volumetric and surface area loading. Volumetric loading (measured in mass of airborne dust per volume of air) may cause hardware to malfunction via dust ingestion or other mechanisms. Surface area loading (measured in mass of settled dust per surface area) may cause hardware to malfunction by altering its thermal properties or by fouling optical surfaces such as camera lenses. This publication describes a method to achieve a stable, user-determined volumetric loading in an arbitrary chamber along with recommendations for how to use such chambers for customized hardware testing.

Benjamin J Sumlin↗
NASA NTRS2019

The Unrealized Potential of Superhydrophobic Substrates in Advanced Life Support Systems

Nearly all water processing equipment aboard spacecraft is to a large extent controlled by capillary forces arising from substrate wetting conditions. Superhydrophobic wetting conditions provide an essentially passive means to keep water away from certain substrates providing a level of no-moving-parts phase separation and control. This work presents a host of non-wetting aqueous microgravity capillary fluidics phenomena arising from interactions with easily fabricated superhydrophobic substrates. The value of such phenomena for potential life support applications aboard spacecraft is clear, especially for substrate properties that are thermally robust, corrosion resistant, and self-cleaning for both long- and short term applications. Large length scale low-g demonstrations of the phenomena are provided in HD video format for the extensive drop tower tests conducted. The broader crosscutting impacts to numerous fluids processing operations for life support are discussed. Current practical applications addressed in light of superhydrophobicity include urine-processing, water recovery, fire safety, and others.

Superhydrophoic↗