Browse Topic: Fluoride

Items (105)
G-3, Aerospace Couplings, Fittings, Hose, Tubing Assemblies
G-3, Aerospace Couplings, Fittings, Hose, Tubing Assemblies
G-3, Aerospace Couplings, Fittings, Hose, Tubing Assemblies
Extension of Analytical Methods for Detailed Characterization of Advanced Combustion Engine Emissions2016-01-233010/17/2016
Advanced combustion strategies used to improve efficiency, emissions, and performance in internal combustion engines (IC) alter the chemical composition of engine-out emissions. The characterization of exhaust chemistry from advanced IC engines requires an analytical system capable of measuring a wide range of compounds. For many years, the widely accepted Coordinating Research Council (CRC) Auto/Oil procedure[1,2] has been used to quantify hydrocarbon compounds between C1 and C12 from dilute engine exhaust in Tedlar polyvinyl fluoride (PVF) bags. Hydrocarbons greater than C12+ present the greatest challenge for identification in diesel exhaust. Above C12, PVF bags risk losing the higher molecular weight compounds due to adsorption to the walls of the bag or by condensation of the heavier compounds. This paper describes two specialized exhaust gas sampling and analytical systems capable of analyzing the mid-range (C10 - C24) and the high range (C24+) hydrocarbon in exhaust. An automated gas chromatograph equipped with a mass spectrometer (GC-MS) sampling system was used to sample middle range hydrocarbons from raw exhaust. A separate sampling system consisting of a filter and XAD traps was used for the collection of particulate-phase and semi-volatile-phase hydrocarbons up to C24+ in dilute exhaust. After extraction, hydrocarbons trapped by the particulate filter and the XAD traps were speciated by a two dimensional gas chromatography mass spectroscopy (GCxGC-MS) technique. These two novel systems allowed more than 2000 compounds to be detected in the exhaust thus extended the analytical capacity in emission characterization.
Fanick, E. RobertKroll, SvitlanaFavela, Kristin
Compatibility of Dimethyl Ether (DME) and Diesel Blends with Fuel System Polymers: A Hansen Solubility Analysis Approach2016-01-08354/5/2016
The compatibility of notable infrastructure elastomers and plastics with DME and its blends with diesel fuel were examined using solubility analysis. The elastomer materials were fluorocarbon, acrylonitrile butadiene rubber (NBR), styrene butadiene (SBR), neoprene, polyurethane and silicone. Plastic materials included polyphenylene sulfide (PPS), polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyoxymethylene (POM), polybutylene terephthalate (PBT), polypropylene (PP), high density polyethylene (HDPE), along with several nylon grades and thermosetting resins. These materials have been rigorously studied with other fuel types, and their volume change results were found to correspond well with their predicted solubility levels. A Hansen solubility analysis was performed for each material with DME, diesel, and blends of both fuel components. The results for the elastomers indicate that DME and its blends with diesel fuel will offer improved compatibility with NBR and SBR materials. Silicone, neoprene and polyurethane show similar solubility potential for any combination of DME and diesel, so no degradation is expected with DME. In contrast, fluorocarbon can be expected to become increasingly incompatible with increased DME concentration. In general, the solubility analysis also indicated that many of the plastic materials can be expected to have good to excellent compatibility with DME and its blends with diesel fuel. The analysis also indicated that polyester resins should exhibit high solubility (and therefore high swelling) in both diesel and DME. However, previous empirical results showed that this result was not an accurate reflection of polyester resin performance in diesel fuel.
Kass, Michael D.Daw, Charles
NASA has an ongoing need for high-temperature solid lubricant coatings to reduce friction and wear in turbine engines, rocket engines, and other mechanical systems. Such lubricants must be thermally and chemically stable in air, vacuum, and reducing environments like hydrogen. Traditional lubricants like oil, grease, and PTFE (Polytetrafluoroethylene), and even more exotic solid lubricants like graphite and molybdenum disulphide, lack such capabilities. The key problem is to identify and formulate a material that possesses good mechanical properties, long-term environmental durability, and acceptable friction and wear-reducing characteristics while being practical to apply to bearings, seals, and other mechanical components.
Thin film, piezoelectric materials generate a small voltage whenever they are deformed, suggesting that they are suitable for tapping energy from freely available resources, such as the wind. Yet their low-energy production levels and lack of electrode durability have hampered development. NASA researchers have invented a system, method, and device for improving the performance and increasing the lifespan of small-form-factor, thin-film electrode, piezoelectric devices capable of interacting with the wind to provide power to wearable devices and stretchable electronics.
Lyndon B. Johnson Space Center, Houston, Texas
G-3, Aerospace Couplings, Fittings, Hose, Tubing Assemblies
Compatibility Assessment of Plastic Infrastructure Materials with Off-Highway Diesel and a Diesel Blend Containing 20 Percent Fast Pyrolysis Bio-Oil2015-01-08934/14/2015
The compatibility of plastic materials used in fuel storage and dispensing applications was determined for an off-highway diesel fuel and a blend containing 20% bio-oil (Bio20) derived from a fast pyrolysis process. Bio20 is not to be confused with B20, which is a diesel blend containing 20% biodiesel. The feedstock, processing, and chemistry of biodiesel are markedly different from bio-oil. Plastic materials included those identified for use as seals, coatings, piping and fiberglass resins, but many are also used in vehicle fueling systems. The plastic specimens were exposed to the two fuel types for 16 weeks at 60°C. After measuring the wetted volume and hardness, the specimens were dried for 65 hours at 60°C and then remeasured to determine extent of property change. A solubility analysis was performed to better understand the performance of plastic materials in fuel blends composed of bio-oil and diesel. All of the plastic materials evaluated in this study exhibited higher solubility (volume swell) with the Bio20 fuel blend. This result was predicted by the solubility analysis. However, there were two notable exceptions; the volume swell results for high density polyethylene (HDPE) and polypropylene (PP) did not correlate with their respective solubility curves. HDPE and PP were also unique in that they were the only two plastics that exhibited pronounced volume expansion in the baseline diesel test fuel. The plastic materials which showed the best compatibility to the bio-oil blend were the barrier plastics polypropylene sulfide (PPS), polyethylene terephthalate (PET or Mylar™), and polytetrafluoroethylene (PTFE or Teflon™). Polyvinylidene fluoride (PVDF or Kynar™) is also used extensively as a permeation barrier material; however, it swelled over 15% when exposed to Bio20. Four grades of nylon were evaluated and the petroleum-derived nylons (Nylon 6, Nylon 6,6, and Nylon 12) showed good compatibility with the test fuels. In contrast, Nylon 11, which is derived from vegetable oil, expanded over 4% with Bio20. HDPE also swelled around 4%, but did so with both test fuels. Two acetal materials and polybutylene terephthalate (PBT) were also observed to swell to 4% with Bio20. Four fiberglass resins were included in the study and they exhibited 10-18% volume expansion. High volume swell was also noted for PP, the PET polyethylene - glycol copolymer (PETG), and polythiourea (PTU). PP also expanded over 15% following exposure to the baseline diesel test fuel.
Kass, Michael D.Janke, ChrisConnatser, RaynellaLewis, SamKeiser, JamesTheiss, Timothy
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