Search NASA⌕ Search

SEARCH · Search NASA

Results for “FOULING”

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 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
DOE OSTI2012

Hydrocarbon Fouling of SCR during PCCI combustion

The combination of advanced combustion with advanced selective catalytic reduction (SCR) catalyst formulations was studied in the work presented here to determine the impact of the unique hydrocarbon (HC) emissions from premixed charge compression ignition (PCCI) combustion on SCR performance. Catalyst core samples cut from full size commercial Fe- and Cu-zeolite SCR catalysts were exposed to a slipstream of raw engine exhaust from a 1.9-liter 4-cylinder diesel engine operating in conventional and PCCI combustion modes. The zeolites which form the basis of these catalysts are different with the Cu-based catalyst made on a chabazite zeolite which las smaller pore structures relative to the Fe-based catalyst. Subsequent to exposure, bench flow reactor characterization of performance and hydrocarbon release and oxidation enabled evaluation of overall impacts from the engine exhaust. The Fe-zeolite NOX conversion efficiency was significantly degraded, especially at low temperatures (<250 C), after the catalyst was exposed to the raw engine exhaust. The degradation of the Fe-zeolite performance was similar for both combustion modes. The Cu-zeolite showed better tolerance to HC fouling at low temperatures compared to the Fe-zeolite but PCCI exhaust had a more significant impact than the exhaust from conventional combustion on the NOX conversion efficiency. Furthermore, chemical analysis of the hydrocarbons trapped on the SCR cores was conducted to better determine chemistry specific effects.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2017

PVDF/PAN Blend Membrane: Preparation, Characterization and Fouling Analysis

Ultrafiltration membranes were prepared from blend of the poly(vinylidene fluoride) (PVDF) with polyacrylonitrile (PAN) via phase inversion method induced by immersion precipitation. N,N-dimethylacetamide (DMAc) and water were used as solvent and coagulant (non-solvent), respectively. The effect of blending ratio on the morphology and antifouling behavior of the prepared membranes was investigated. The performance of the membranes was evaluated by using cross flow filtration of pure water and buffered bovine serum albumin (BSA) solution as feed. Contact angle measurements indicated that the hydrophilicities of the PVDF/PAN membranes increased by increasing PAN concentration in the casting solution. The minimum BSA rejection was obtained for the membrane with 10% of PAN. However, higher values of PAN result in pore blockage of the membrane and an increase in the irreversible fouling resistance.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Surface engineering of polymeric membranes with metal oxides for improved fouling resistance and superior oil-water separation

Rapid industrial growth has increased the need for efficient membranes to separate oil-water emulsions. Polyvinylidene fluoride (PVDF) membranes, although widely used due to their chemical inertness and favorable mechanical properties, suffer from fouling due to their intrinsic hydrophobicity. Modifying these membranes after fabrication offers a practical solution as it easily fits into existing large-scale manufacturing processes. Atomic layer deposition (ALD), an atomically-precise vapor phase surface modification technique, can create ultrathin metal oxide layers that greatly improve membrane hydrophilicity without significantly affecting the original pore size. However, PVDF's lack of reactive chemical moieties makes ALD challenging. Here, in this study, we present a simple alkali treatment that greatly enhances ALD nucleation and growth on PVDF membranes. This treatment imparts exceptional oil-water emulsion separation capabilities and antifouling behavior in PVDF membranes after just a few ALD cycles, surpassing the performance of PVDF membranes coated with hundreds of ALD cycles. This dramatic reduction in the number of ALD cycles required could enable cost-effective modification of commercial PVDF membranes at scale using spatial, roll-to-roll ALD. These modified membranes outperform reported modified PVDF membranes, with >99 % permeance recovery and <1 % irreversible loss of permeance and >98 % oil rejection from oil-water emulsions over 100 h continuous operation, making them promising for advanced water purification technologies.

Atomic layer deposition↗
DOE OSTI2014

Characterization of Solids in Fouled Modular Caustic Side Solvent Extraction Unit (MCU) Prefilter/Coalescer Media

Prefilters and coalescers utilized during the Modular Caustic Side Solvent Extraction Unit (MCU) processing of Salt Batches 5 and 6 were sampled and submitted to SRNL for characterization, for the purpose of identifying solid phase constituents potentially fouling the pores. Specifically, three samples were received and characterized: 1) a decontaminated salt solution (DSS) prefilter (PF) sample; 2) a DSS coalescer sample; and 3) a strip effluent (SE) coalescer sample. Aliquots of the samples were analyzed by X-ray Diffraction (XRD), Fourier Transform Infrared (FTIR) Spectroscopy, and Scanning Electron Microscopy (SEM)/Energy Dispersive Spectroscopy (EDS). Other aliquots of the samples were leached in acid solution, and the leachates were analyzed by Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES). In addition, modeling was performed to provide a basis for comparison of the analytical results.

Coalescer↗
NASA NTRS1981

A heat exchanger computational procedure for temperature-dependent fouling

A novel heat exchanger computational procedure is described which provides a means of rapidly calculating the distributions of fluid and wall temperatures, deposit formation, and pressure loss at various points in a heat exchanger. The procedure is unique in that it is capable of treating wide variations in heat exchanger geometry without recourse to restrictive assumptions concerning heat exchanger type (e.g., co-flow, counterflow, cross flow devices, etc.). The analysis has been used extensively to predict the performance of cross-counterflow heat exchangers in which one fluid behaves as a perfect gas (e.g., air) while the other fluid is assumed to be a distillate fuel. The model has been extended to include the effects on heat exchanger performance of time varying inflow conditions. Heat exchanger performance degradation due to deposit formation with time can be simulated, making this procedure useful in predicting the effects of temperature-dependent fouling.

Chiappetta, L. M.↗
NASA NTRS1983

ECUT: Energy Conversion and Utilization Technologies program biocatalysis research activity. Potential membrane applications to biocatalyzed processes: Assessment of concentration polarization and membrane fouling

Separation and purification of the products of biocatalyzed fermentation processes, such as ethanol or butanol, consumes most of the process energy required. Since membrane systems require substantially less energy for separation than most alternatives (e.g., distillation) they have been suggested for separation or concentration of fermentation products. This report is a review of the effects of concentration polarization and membrane fouling for the principal membrane processes: microfiltration, ultrafiltration, reverse osmosis, and electrodialysis including a discussion of potential problems relevant to separation of fermentation products. It was concluded that advanced membrane systems may result in significantly decreased energy consumption. However, because of the need to separate large amounts of water from much smaller amounts of product that may be more volatile than wate, it is not clear that membrane separations will necessarily be more efficient than alternative processes.

Ingham, J. D.↗
DOE OSTI2012

Airfoil-shaped micro-mixers for reducing fouling on membrane surfaces

An array of airfoil-shaped micro-mixers that enhances fluid mixing within permeable membrane channels, such as used in reverse-osmosis filtration units, while minimizing additional pressure drop. The enhanced mixing reduces fouling of the membrane surfaces. The airfoil-shaped micro-mixer can also be coated with or comprised of biofouling-resistant (biocidal/germicidal) ingredients.

47 OTHER INSTRUMENTATION↗
DOE OSTI2013

Method for predicting fouling tendency of a hydrocarbon-containing feedstock

Disclosed herein is a method involving the steps of (a) precipitating an amount of asphaltenes from a liquid sample of a first hydrocarbon-containing feedstock having solvated asphaltenes therein with one or more first solvents in a column; (b) determining one or more solubility characteristics of the precipitated asphaltenes; (c) analyzing the one or more solubility characteristics of the precipitated asphaltenes; and (d) correlating a measurement of feedstock fouling tendency for the first hydrocarbon-containing feedstock sample with a mathematical parameter derived from the results of analyzing the one or more solubility characteristics of the precipitated asphaltenes.

09 BIOMASS FUELS↗
DOE OSTI2019

System and method for disinfection and fouling prevention in the treatment of water

A treatment system for treating water, such as produced water that is produced during hydraulic fracturing. The system employs a combination of a plasma spark discharge and an RF oscillating electric field. The plasma spark discharge and the RF oscillating electric field may be employed simultaneously or in an overlapping manner within a chamber to treat the water. The treatment system is able to kill microorganisms as well as reduce or eliminate fouling due to, for example, bicarbonates. In some embodiments, grids are employed to further enhance the heat produced by the RF oscillating electric field.

42 ENGINEERING↗
DOE OSTI2019

System including a direct contact desublimating heat exchanger for reducing fouling

A process to prevent fouling using a desublimating heat exchanger is disclosed. An outlet stream from the desublimating heat exchanger may be split into a plurality of parallel streams. The parallel streams may be sent through other devices for performing a unit operation, and the devices for performing a unit operation may change the temperature of at least one of the parallel streams. Parallel streams of differing temperature may emerge from the devices for performing a unit operation. The parallel streams of differing temperature may be sent to a mixing chamber. A mixed stream of uniform temperature may emerge from the mixing chamber, and the mixed stream may be recycled back to the desublimating heat exchanger. The mixing chamber may be separate from the desublimating heat exchanger, or the parallel streams of differing temperature may be mixed in the desublimating heat exchanger.

Baxter, Larry↗
DOE OSTI2015

Hydrophobicity of Rare-earth Oxide Ceramics and their Application in Promoting Sustained Dropwise Condensation and Corrosion and Fouling Mitigation in Hydropower Systems

Hydrophobic surfaces that are robust can have widespread applications in various industries including energy, hydropower, and transportation. In particular, hydrophobic materials promote dropwise condensation, which results in heat transfer coefficients that can be an order of magnitude higher than those seen in conventional filmwise condensation. Existing durable materials such as metals and ceramics are generally hydrophilic and require polymeric modifiers to render them hydrophobic, but these modifiers deteriorate in harsh environments. Therefore, robust hydrophobic surfaces have been difficult to realize and their widespread applicability has been limited. In this project, the class of ceramics comprising the lanthanide series rare-earth oxides (REOs) is studied for their hydrophobic potential. The unique electronic structure of the rare-earth metal atom inhibits hydrogen bonding with interfacial water molecules resulting in a hydrophobic hydration structure where the surface oxygen atoms are the only hydrogen bonding sites. Despite being inherently hydrophobic, the presence of excess surface oxygen on REOs can lead to increased hydrogen bonding and thereby reduce their hydrophobicity. Using X-ray Photoelectron Spectroscopy (XPS) and wetting measurements, surface stoichiometry and surface relaxations have been shown to impact wetting properties of REOs. Specifically, freshly sputtered ceria is shown to be hydrophilic due to excess surface oxygen (shown to have an O/Ce ratio of ~3), which when relaxed in a clean, ultra-high vacuum environment isolated from airborne contaminants reaches close to stoichiometric O/Ce ratio (~2.2) and becomes hydrophobic. Further, airborne hydrocarbon contaminants do not exclusively impact the wetting properties of REOs, and relaxed REOs are intrinsically hydrophobic. This project also demonstrates that thin-film coatings (~300 nm) of relaxed hydrophobic REOs show sustained dropwise condensation behavior for over 100 hours at accelerated saturated steam conditions without compromising structural integrity or hydrophobicity, and produce an almost tenfold enhancement in the heat transfer co-efficient (103 ± 5 kW/m2K) compared to conventional filmwise condensation (usually <10 kW/m2K). It is envisioned that robust hydrophobic rare-earth oxide ceramics will have far reaching technological applications, especially in dropwise condensation and fouling mitigation in hydropower systems.

13 HYDRO ENERGY↗
DOE OSTI2025

Zwitterionic Photocurable Resin for High‐Resolution 3D Printing of Ultralow‐Fouling Microstructures

High‐resolution 3D printing technologies are enabling a new generation of microstructured materials for applications where biocompatibility is critical. However, most conventional 3D‐printable resins yield materials that exhibit trade‐offs between antifouling properties and mechanical robustness, limiting their applicability in living systems. In nature, zwitterionic surface groups form tightly bound hydration layers that act as effective barriers against protein and cell attachment. Inspired by this strategy, a zwitterionic acrylamide‐based photoresist—carboxybetaine di‐methacrylamide (CBDA)—is developed for projection‐based vat photopolymerization, enabling the fabrication of complex microarchitectures with exceptional antifouling properties. The bifunctional monomer allows the formation of dense, cross‐linked networks that resist swelling while maintaining a high density of zwitterionic groups. Printed structures exhibit strong resistance to protein and cell adhesion, as confirmed by porcine blood assays, alongside robust mechanical performance. As a demonstration, a tubular structure featuring a negative Poisson's ratio lattice is printed to showcase structural fidelity and versatility. This resin formulation offers a broadly applicable strategy for fabricating microscale devices and surfaces where antifouling performance and structural integrity are both essential—spanning biomedical interfaces, soft robotics, and beyond.

3D printing↗
DOE OSTI2011

Spectroscopic Investigations of the Fouling Process on Nafion Membranes in Vanadium Redox Flow Batteries

The Nafion-117 membrane used in vanadium redox flow battery (VRFB) is analyzed by X-ray photoelectron spectroscopy (XPS) and nuclear magnetic resonance (NMR) spectroscopy. The XPS study reveals the chemical identity and environment of vanadium cations accumulated at the surface due to their low diffusivity. On the other hand, the 17O NMR spectrum explores the diffused vanadium cation from the bulk part of Nafion and shows the chemical bonding of cation and the host membrane. The 19F NMR shows the basic Nafion structure is not altered due to the presence of diffused vanadium cation. Based on these spectroscopic studies, the chemical environment of diffused vanadium cation in the Nafion membrane is discussed. This study also shed light into the possible cause for the high diffusivity of certain vanadium cations inside the Nafion membranes.

25 ENERGY STORAGE↗
DOE OSTI2014

Various mortars for anti-fouling purposes in marine environments

The antifouling properties for some mortars with steel making slags were investigated by real marine immersion tests and a unique laboratory acceleration tests with a specially devised biofilm acceleration reactors. Mortars mixed with steel making slags containing abundant iron elements tended to form biofilm and also bifouling. The two kinds of biofilm formation tests were used in this study. Real immersion in marine environments and laboratory test with a specially devised biofilm acceleration reactor. The former evaluated the biofouling characteristics more properly, while the latter did the biofilm formation characteristics more effectively.

36 MATERIALS SCIENCE↗