Science.gov

Sample records for aqueous foam flow

  1. Rheology of aqueous foams

    NASA Astrophysics Data System (ADS)

    Dollet, Benjamin; Raufaste, Christophe

    2014-10-01

    Aqueous foams are suspensions of bubbles inside aqueous phases. Their multiphasic composition leads to a complex rheological behavior that is useful in numerous applications, from oil recovery to food/cosmetic processing. Their structure is very similar to the one of emulsions, so that both materials share common mechanical properties. In particular, the presence of surfactants at the gas-liquid interfaces leads to peculiar interfacial and dissipative properties. Foam rheology has been an active research topics and is already reported in several reviews, most of them covering rheometry measurements at the scale of the foam, coupled with interpretations at the local scale of bubbles or interfaces. In this review, we start following this approach, then we try to cover the multiscale features of aqueous foam flows, emphasizing regimes where intermediate length scales need to be taken into account or regimes fast enough regarding internal time scales so that the flow goes beyond the quasi-static limit. xml:lang="fr"

  2. Liquid oil that flows in spaces of aqueous foam without defoaming.

    PubMed

    Sonoda, Junko; Sakai, Takaya; Inomata, Yukio

    2014-08-07

    A very interesting phenomenon has been observed in which foam formed from an aqueous fatty acid potassium salt solution spontaneously absorbs liquid oil immediately upon contact without defoaming. Although this phenomenon initially appeared to be based on capillary action, it was clarified that the liquid oil that flows in foam film did not wet the air/water interface. In this study, it is discussed why aqueous foam can spontaneously soak up liquid oil without defoaming using equilibrium surface tension, dynamic oil/water interfacial tension, and image analysis techniques. The penetration of oil was attributed both to the dynamic decrease in the surface tension at the oil/water interface and to Laplace pressure, depending on the curvature of the plateau border. Therefore, the foam does not absorb the oil, but the oil spontaneously penetrates the foam. This interesting behavior can be expected to be applied to aqueous detergents for liquid oil removal.

  3. Flow of an aqueous foam through a two-dimensional porous medium: a pore scale investigation

    NASA Astrophysics Data System (ADS)

    Meheust, Y.; Jones, S. A.; Dollet, B.; Cox, S.; Cantat, I.

    2012-12-01

    Flowing foams are used in many engineering and technical applications. A well-known application is oil recovery. Another one is the remediation of polluted soil: the foam is injected into the ground in order to mobilize chemical species present in the medium. Apart from potential interesting physico-chemical and biochemical properties, foams have peculiar flow properties that might be of benefit to the application. We address here this physical aspect of the topic. As a precursor to the study of foam flow through a complex porous material, we first study the behavior of an aqueous two-dimensional foam flowing through a medium consisting of two parallel channels with different widths, at fixed medium porosity, that is, at fixed total combined width of the two channels. The flow velocity, and hence flux, in each channel is measured by analyzing images of the flowing foam. It is then compared to a theoretical model, the basic assumption of which is that the pressure drop along a channel is identical for both channels. This pressure drop both consists of (i) a dynamic pressure drop, which is controlled by bubble-wall friction and depends on the foam velocity in the channel, and (ii) a capillary pressure drop over the bubble films that emerge at the channel outlet, the latter pressure drop being controlled by the radius of curvature of the bubble film. Based on this assumption, the dependence of the ratio of the foam velocities in the two channels is inferred as a function of the channel width ratio. It compares well to the measurements and shows that the flow behavior is highly dependent on the foam structure within the narrowest of the two channels, especially when a "bamboo" structure is obtained. Consequently, the flux in a channel is found to have a more complicated relation to the channel width than expected for the flow of a standard Newtonian fluid in the same geometry. We provide a comparison to this reference configuration. We then study the flow of the same

  4. Flow of a two-dimensional aqueous foam in two parallel channels

    NASA Astrophysics Data System (ADS)

    Jones, S.; Cantat, I.; Dollet, B.; Meheust, Y.

    2012-04-01

    Flowing foams are used in many engineering and technical applications. A well-known application is oil recovery. Another one is the remediation of polluted soil: the foam is injected into the ground in order to mobilize chemical species that are initially present in the medium. Apart from potential interesting physico-chemical and biochemical properties, foams have pecular flow properties that might be used in order to reach regions of the medium that are normally the least permeable. We study here this physical aspect of the topic. As a precursor to the study of foam flow through a complex porous material, we study the behaviour of an aqueous two-dimensional foam flowing through a medium consisting of two parallel channels with different widths, at fixed medium porosity, that is, at fixed total combined width of the two channels. The flow velocity, and hence flux, in each channel is measured by analyzing images of the flowing foam. The corresponding pressure drop along each channel is calculated based on theoretical arguments involving both (i) a dynamic pressure drop, which is controlled by bubble-wall friction, and (ii) possibly a capillary pressure drop over the bubble films that emerge at the channel outlet, the latter pressure drop being controlled by the radius of curvature of the bubble film. The flow behaviour of the foam happens to not uniquely be determined by the channel width, as would be the case for a Newtonian fluid, but also to be highly dependent on the foam structure within the narrowest of the two channel, especially when a "bamboo" structure is obtained. Consequently, the flux in a channel is found to have a more complicated relation to the channel width than expected. We try to define a corresponding medium permeability and compare it to the permeability expected for the flow of a standard newtonian fluid in the same geometry.

  5. The Melting of Aqueous Foams

    NASA Technical Reports Server (NTRS)

    Durian, Douglas J.; Gopal, Anthony D.; Vera, Moin U.; Langer, Stephen A.

    1996-01-01

    Diffusing-wave spectroscopy measurements show that ordinarily solid aqueous foams flow by a series of stick-slip avalanche-like rearrangements of neighboring bubbles from one tight packing configuration to another. Contrary to a recent prediction, the distribution of avalanche sizes do not obey a power-law distribution characteristic of self-organized criticality. This can be understood from a simple model of foam mechanics based on bubble-bubble interactions.

  6. An experimental investigation of pressure drop of aqueous foam in laminar tube flow

    SciTech Connect

    Blackwell, B.F.; Sobolik, K.B.

    1987-04-01

    This report is the first of two detailing pressure-drop and heat-transfer measurements made at the Foam Flow Heat Transfer Loop. The work was motivated by a desire to extend the application of aqueous foam from petroleum drilling to geothermal drilling. Pressure-drop measurements are detailed in this report; a forthcoming report (SAND85-1922) will describe the heat-transfer measurements. The pressure change across a 2.4-m (8-ft) length of the 2.588-cm (1.019-in.) ID test section was measured for liquid volume fractions between 0.05 and 0.35 and average velocities between 0.12 and 0.80 m/s (0.4 and 2.6 ft/s). The resulting pressure-drop/flow-rate data were correlated to a theoretical model for a Bingham plastic. Simple expressions for the dynamic viscosity and the yield stress as a function of liquid volume fraction were estimated.

  7. Velocimetry of aqueous foam drainage

    NASA Astrophysics Data System (ADS)

    Kennedy, Matthew J.; Fleming, James W.

    2011-11-01

    We study the flow behavior of a freely draining aqueous foam using microparticle image velocimetry. Video shows liquid traveling uphill along the bubble surfaces, counter-directional to the primary flow. Most theoretical models of foam drainage avoid direct calculation of the flow at the gas-liquid interface. Rather, they treat the effect of surface flow empirically due to lack of experimental and theoretical understanding of the forces which cause flow at the surface. This uphill flow represents a significant component of the overall flow. Understanding the surface-driven flow can improve predictions of water-retention time. In the present work, we use a proprietary fire-suppression foam solution comprising hydrocarbon-based non-fluorinated surfactants in water. At the start of drainage, the mean upward flow speed is 0.2 +/- 0.1 mm/s while the mean downward flow speed is 0.8 +/- 0.1 mm/s. The local bubble size at the location-under-imaging is 0.6 mm with a coefficient of variation of 50%. Ongoing efforts concern the effect of the liquid solution constituents on the uphill flow and the effect of bubble size on drainage time. NRC/NRL Postdoctoral Fellow

  8. The flow of an aqueous foam through a two-dimensional porous medium

    NASA Astrophysics Data System (ADS)

    Dollet, B.; Jones, S. A.; Géraud, B.; Meheust, Y.; Cox, S. J.; Cantat, I.

    2013-12-01

    Flowing foams are used in many engineering and technical applications. A well-known application is oil recovery. Another one is the remediation of polluted soils: the foam is injected into the ground in order to mobilize chemical species present in the medium. Apart from potential interesting physico-chemical and biochemical properties, foams have peculiar flow properties that applications might benefit of. In particular, viscous dissipation arises mostly from the contact zones between the soap films and the walls, which results in peculiar friction laws allowing the foam to invade narrow pores more efficiently than Newtonian fluids would. We investigate the flow of a two-dimensional foam in three geometrical configurations. The flow velocity field and pressure field can both be reconstructed from the kinematics of the foam bubbles. We first consider a medium consisting of two parallel channels with different widths, at fixed medium porosity, that is, at fixed total combined width of the two channels. The flow behavior is highly dependent on the foam structure within the narrowest of the two channels [1]; consequently, the flux ratio between the two channels exhibits a non-monotonic dependence on the ratio of their widths. We then consider two parallel channels that are respectively convergent and divergent. The resulting flow kinematics imposes asymmetric bubble deformations in the two channels; these deformations strongly impact the foam/wall friction, and consequently the flux distribution between the two channels, causing flow irreversibility. We quantitatively predict the flux ratio as a function of the channel widths by modeling pressure drops of both viscous and capillary origins. This study reveals the crucial importance of boundary-induced bubble deformation on the mobility of a flowing foam. We then study how film-wall friction, capillary pressures and bubble deformation impact the flow of a foam in a two-dimensional porous medium consisting of randomly

  9. Dynamics of Aqueous Foam Drops

    NASA Technical Reports Server (NTRS)

    Akhatov, Iskander; McDaniel, J. Gregory; Holt, R. Glynn

    2001-01-01

    We develop a model for the nonlinear oscillations of spherical drops composed of aqueous foam. Beginning with a simple mixture law, and utilizing a mass-conserving bubble-in-cell scheme, we obtain a Rayleigh-Plesset-like equation for the dynamics of bubbles in a foam mixture. The dispersion relation for sound waves in a bubbly liquid is then coupled with a normal modes expansion to derive expressions for the frequencies of eigenmodal oscillations. These eigenmodal (breathing plus higher-order shape modes) frequencies are elicited as a function of the void fraction of the foam. A Mathieu-like equation is obtained for the dynamics of the higher-order shape modes and their parametric coupling to the breathing mode. The proposed model is used to explain recently obtained experimental data.

  10. Aqueous foam toxicology evaluation and hazard review

    SciTech Connect

    Archuleta, M.M.

    1995-10-01

    Aqueous foams are aggregates of bubbles mechanically generated by passing air or other gases through a net, screen, or other porous medium that is wetted by an aqueous solution of surface-active foaming agents (surfactants). Aqueous foams are important in modem fire-fighting technology, as well as for military uses for area denial and riot or crowd control. An aqueous foam is currently being developed and evaluated by Sandia National Laboratories (SNL) as a Less-Than-Lethal Weapon for the National Institute of Justice (NIJ). The purpose of this study is to evaluate the toxicity of the aqueous foam developed for the NIJ and to determine whether there are any significant adverse health effects associated with completely immersing individuals without protective equipment in the foam. The toxicity of the aqueous foam formulation developed for NIJ is determined by evaluating the toxicity of the individual components of the foam. The foam is made from a 2--5% solution of Steol CA-330 surfactant in water generated at expansion ratios ranging from 500:1 to 1000:1. SteoI CA-330 is a 35% ammonium laureth sulfate in water and is produced by Stepan Chemical Company and containing trace amounts (<0.1%) of 1,4-dioxane. The results of this study indicate that Steol CA-330 is a non-toxic, mildly irritating, surfactant that is used extensively in the cosmetics industry for hair care and bath products. Inhalation or dermal exposure to this material in aqueous foam is not expected to produce significant irritation or systemic toxicity to exposed individuals, even after prolonged exposure. The amount of 1,4-dioxane in the surfactant, and subsequently in the foam, is negligible and therefore, the toxicity associated with dioxane exposure is not significant. In general, immersion in similar aqueous foams has not resulted in acute, immediately life-threatening effects, or chronic, long-term, non-reversible effects following exposure.

  11. Highly enhanced electrochemical activity of Ni foam electrodes decorated with nitrogen-doped carbon nanotubes for non-aqueous redox flow batteries

    NASA Astrophysics Data System (ADS)

    Lee, Jungkuk; Park, Min-Sik; Kim, Ki Jae

    2017-02-01

    Nitrogen-doped carbon nanotubes (NCNTs) are directly grown on the surface of a three-dimensional (3D) Ni foam substrate by floating catalytic chemical vapor deposition (FCCVD). The electrochemical properties of the 3D NCNT-Ni foam are thoroughly examined as a potential electrode for non-aqueous redox flow batteries (RFBs). During synthesis, nitrogen atoms can be successfully doped onto the carbon nanotube (CNT) lattices by forming an abundance of nitrogen-based functional groups. The 3D NCNT-Ni foam electrode exhibits excellent electrochemical activities toward the redox reactions of [Fe (bpy)3]2+/3+ (in anolyte) and [Co(bpy)3]+/2+ (in catholyte), which are mainly attributed to the hierarchical 3D structure of the NCNT-Ni foam electrode and the catalytic effect of nitrogen atoms doped onto the CNTs; this leads to faster mass transfer and charge transfer during operation. As a result, the RFB cell assembled with 3D NCNT-Ni foam electrodes exhibits a high energy efficiency of 80.4% in the first cycle; this performance is maintained up to the 50th cycle without efficiency loss.

  12. 46 CFR 108.474 - Aqueous film forming foam systems.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 4 2011-10-01 2011-10-01 false Aqueous film forming foam systems. 108.474 Section 108... DESIGN AND EQUIPMENT Fire Extinguishing Systems Foam Extinguishing Systems § 108.474 Aqueous film forming foam systems. Aqueous film forming foam systems may be installed if approved by the Commandant....

  13. 46 CFR 108.474 - Aqueous film forming foam systems.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 4 2012-10-01 2012-10-01 false Aqueous film forming foam systems. 108.474 Section 108... DESIGN AND EQUIPMENT Fire Extinguishing Systems Foam Extinguishing Systems § 108.474 Aqueous film forming foam systems. Aqueous film forming foam systems may be installed if approved by the Commandant....

  14. 46 CFR 108.474 - Aqueous film forming foam systems.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 4 2014-10-01 2014-10-01 false Aqueous film forming foam systems. 108.474 Section 108... DESIGN AND EQUIPMENT Fire Extinguishing Systems Foam Extinguishing Systems § 108.474 Aqueous film forming foam systems. Aqueous film forming foam systems may be installed if approved by the Commandant....

  15. 46 CFR 108.474 - Aqueous film forming foam systems.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Aqueous film forming foam systems. 108.474 Section 108... DESIGN AND EQUIPMENT Fire Extinguishing Systems Foam Extinguishing Systems § 108.474 Aqueous film forming foam systems. Aqueous film forming foam systems may be installed if approved by the Commandant....

  16. 46 CFR 108.474 - Aqueous film forming foam systems.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 4 2013-10-01 2013-10-01 false Aqueous film forming foam systems. 108.474 Section 108... DESIGN AND EQUIPMENT Fire Extinguishing Systems Foam Extinguishing Systems § 108.474 Aqueous film forming foam systems. Aqueous film forming foam systems may be installed if approved by the Commandant....

  17. Blast mitigation capabilities of aqueous foam.

    SciTech Connect

    Hartman, William Franklin; Larsen, Marvin Elwood; Boughton, Bruce A.

    2006-02-01

    A series of tests involving detonation of high explosive blanketed by aqueous foam (conducted from 1982 to 1984) are described in primarily terms of recorded peak pressure, positive phase specific impulse, and time of arrival. The investigation showed that optimal blast mitigation occurs for foams with an expansion ratio of about 60:1. Simple analyses representing the foam as a shocked single phase mixture are presented and shown inadequate. The experimental data demonstrate that foam slows down and broadens the propagated pressure disturbance relative to a shock in air. Shaped charges and flyer plates were evaluated for operation in foam and appreciable degradation was observed for the flyer plates due to drag created by the foam.

  18. Blast wave mitigation by dry aqueous foams

    NASA Astrophysics Data System (ADS)

    Del Prete, E.; Chinnayya, A.; Domergue, L.; Hadjadj, A.; Haas, J.-F.

    2013-02-01

    This paper presents results of experiments and numerical modeling on the mitigation of blast waves using dry aqueous foams. The multiphase formalism is used to model the dry aqueous foam as a dense non-equilibrium two-phase medium as well as its interaction with the high explosion detonation products. New experiments have been performed to study the mass scaling effects. The experimental as well as the numerical results, which are in good agreement, show that more than an order of magnitude reduction in the peak overpressure ratio can be achieved. The positive impulse reduction is less marked than the overpressures. The Hopkinson scaling is also found to hold particularly at larger scales for these two blast parameters. Furthermore, momentum and heat transfers, which have the main dominant role in the mitigation process, are shown to modify significantly the classical blast wave profile and thereafter to disperse the energy from the peak overpressure due to the induced relaxation zone. In addition, the velocity of the fireball, which acts as a piston on its environment, is smaller than in air. Moreover, the greater inertia of the liquid phase tends to project the aqueous foam far from the fireball. The created gap tempers the amplitude of the transmitted shock wave to the aqueous foam. As a consequence, this results in a lowering of blast wave parameters of the two-phase spherical decaying shock wave.

  19. Capillary rise of oil in an aqueous foam

    NASA Astrophysics Data System (ADS)

    Piroird, Keyvan; Lorenceau, Élise

    2012-11-01

    Oil is usually known as an anti-foaming agent. Yet, it has been shown that oil droplets present in the foaming solution can have the opposite effect and stabilize a foam when unable to cross the air/water interface. In these previous studies, oil is first emulsified and then mixed with air to generate a foam. In this work, we report experiments where an aqueous foam is put in direct contact with a large oil drop. With the appropriate choice of oil and surfactants, oil spontaneously invades the liquid network of the foam without damaging it. We study the dynamics of penetration at the scale of a single Plateau border, that acts as a ``liquid capillary tube'' in which oil flows in an unbroken stream. At the end of the experiment, a long and stable cylinder of oil is formed in the Plateau border. This cylinder breaks up into droplets when, following a rearrangement, oil is transferred from the Plateau border to a soap film.

  20. Evaluation of aqueous-foam surfactants for geothermal drilling fluids

    SciTech Connect

    Rand, P.B.; Montoya, O.J.

    1983-07-01

    Aqueous foams are potentially useful drilling and cleanout fluids for geothermal applications. Successful use of foams requires surfactants (foaming agents) that can survive in the high-temperature geothermal environment. In this study, solutions of aqueous-foam-forming surfactants have been exposed to 260/sup 0/C (500/sup 0/F) and 310/sup 0/C (590/sup 0/F) in various chemical environments to determine if they can survive and make foams after exposure. Comparison of foams before and after exposure and the change in solution pH were used to evaluate their performance. Controlled liquid-volume-fraction foams, made in a packed-bed foam generator, were used for all tests. These tests have shown that many commercially available surfactants can survive short high-temperature cycles in mild acids, mild bases, and salt solutions as evidenced by their ability to make foams after exposure to high temperatures.

  1. Analysis of shock-wave propagation in aqueous foams using shock tube experiments

    NASA Astrophysics Data System (ADS)

    Jourdan, G.; Mariani, C.; Houas, L.; Chinnayya, A.; Hadjadj, A.; Del Prete, E.; Haas, J.-F.; Rambert, N.; Counilh, D.; Faure, S.

    2015-05-01

    This paper reports experimental results of planar shock waves interacting with aqueous foams in a horizontal conventional shock tube. Four incident shock wave Mach numbers are considered, ranging from 1.07 to 1.8, with two different foam columns of one meter thickness and expansion ratios of 30 and 80. High-speed flow visualizations are used along with pressure measurements to analyse the main physical mechanisms that govern shock wave mitigation in foams. During the shock/foam interaction, a precursor leading pressure jump was identified as the trace of the liquid film destruction stage in the foam fragmentation process. The corresponding pressure threshold is found to be invariant for a given foam. Regarding the mitigation effect, the results show that the speed of the shock is drastically reduced and that wetter is the foam, slower are the transmitted waves. The presence of the foam barrier attenuates the induced pressure impulse behind the transmitted shock, while the driest foam appears to be more effective, as it limits the pressure induced by the reflected shock off the foam front. Finally, it was found that the pressure histories in the two-phase gas-liquid mixture are different from those previously obtained within a cloud of droplets. The observed behavior is attributed to the process of foam fragmentation and to the modification of the flow topology past the shock. These physical phenomena occurring during the shock/foam interaction should be properly accounted for when elaborating new physical models.

  2. Microgravity studies of aqueous wet foams.

    PubMed

    Langevin, D; Vignes-Adler, M

    2014-03-01

    Foams and foaming pose important questions and problems for both fundamental research and practical applications. Despite the fact that foams have been extensively studied, many aspects of foam physics and chemistry still remain unclear. Experiments on foams performed under microgravity can be extended far beyond their counterpart where gravity is fully present (i.e. most experiments on Earth). They allow, in particular, observation of the wet foams obtained during the foaming process; on Earth, foams at this stage evolve too quickly due to gravity drainage and cannot be studied. This paper reviews the existing studies of foams under microgravity, which include studies in parabolic flights, in sounding rockets and in the International Space Station.

  3. Fluid Physics of Foam Evolution and Flow

    NASA Technical Reports Server (NTRS)

    Aref, H.; Thoroddsen, S. T.; Sullivan, J. M.

    2003-01-01

    The grant supported theoretical, numerical and experimental work focused on the elucidation of the fluid physics of foam structure, evolution and flow. The experimental work concentrated on these subject areas: (a) Measurements of the speed of reconnections within a foam; (b) statistics of bubble rearrangements; and (c) three-dimensional reconstruction of the foam structure. On the numerical simulation and theory side our efforts concentrated on the subjects: (a) simulation techniques for 2D and 3D foams; (b) phase transition in a compressible foam; and (c) TCP structures.

  4. Fluid Physics of Foam Evolution and Flow

    NASA Technical Reports Server (NTRS)

    Aref, H.; Thoroddsen, S. T.; Sullivan, J. M.

    2003-01-01

    The grant supported theoretical, numerical and experimental work focused on the elucidation of the fluid physics of foam structure, evolution and flow. The experimental work concentrated on these subject areas: (a) Measurements of the speed of reconnections within a foam; (b) statistics of bubble rearrangements; and (c) three-dimensional reconstruction of the foam structure. On the numerical simulation and theory side our efforts concentrated on the subjects: (a) simulation techniques for 2D and 3D foams; (b) phase transition in a compressible foam; and (c) TCP structures.

  5. Aspiration tests in aqueous foam using a breathing simulator

    SciTech Connect

    Archuleta, M.M.

    1995-12-01

    Non-toxic aqueous foams are being developed by Sandia National Laboratories (SNL) for the National Institute of Justice (NIJ) for use in crowd control, cell extractions, and group disturbances in the criminal justice prison systems. The potential for aspiration of aqueous foam during its use and the resulting adverse effects associated with complete immersion in aqueous foam is of major concern to the NIJ when examining the effectiveness and safety of using this technology as a Less-Than-Lethal weapon. This preliminary study was designed to evaluate the maximum quantity of foam that might be aspirated by an individual following total immersion in an SNL-developed aqueous foam. A.T.W. Reed Breathing simulator equipped with a 622 Silverman cam was used to simulate the aspiration of an ammonium laureth sulfate aqueous foam developed by SNL and generated at expansion ratios in the range of 500:1 to 1000:1. Although the natural instinct of an individual immersed in foam is to cover their nose and mouth with a hand or cloth, thus breaking the bubbles and decreasing the potential for aspiration, this study was performed to examine a worst case scenario where mouth breathing only was examined, and no attempt was made to block foam entry into the breathing port. Two breathing rates were examined: one that simulated a sedentary individual with a mean breathing rate of 6.27 breaths/minute, and one that simulated an agitated or heavily breathing individual with a mean breathing rate of 23.7 breaths/minute. The results of this study indicate that, if breathing in aqueous foam without movement, an air pocket forms around the nose and mouth within one minute of immersion.

  6. Effects of oil on aqueous foams: electrical conductivity of foamed emulsions.

    PubMed

    Yan, Yong-Li; Shan, Cheng; Wang, Yao; Deng, Qiang

    2014-10-06

    Three-phase foams containing dispersed oils (also called foamed emulsion) are usually encountered in such areas as enhanced oil recovery, food foams, and in foams containing antifoams. The presence of oil causes these complex fluids to exhibit extraordinary properties in contrast to aqueous foams. We experimentally investigated, for the first time, the conductive properties of the foamed emulsions and found that the electrical conductivity increases monotonically with the volumetric liquid fraction, presenting a linear relationship. Combined with the analysis on the foaming capacity and microstructure of this complex fluid, the conductive mechanism is revealed. In these foamed emulsions, the whole conductive network is comprised of two levels of structural hierarchy, which displays a different mechanism from those of the conventional aqueous foams. The lamella of emulsions is taken as primary electrical channel, whereas the secondary electrical channel occurs in the lamella between two bubbles. This conductive behaviour is attributed to the microstructure properties of the foamed emulsions. We believe that such findings are potentially important for a better understanding of the fundamentals of these tri-phase dispersion systems.

  7. Measurement of Aqueous Foam Rheology by Acoustic Levitation

    NASA Technical Reports Server (NTRS)

    McDaniel, J. Gregory; Holt, R. Glynn; Rogers, Rich (Technical Monitor)

    2000-01-01

    An experimental technique is demonstrated for acoustically levitating aqueous foam drops and exciting their spheroidal modes. This allows fundamental studies of foam-drop dynamics that provide an alternative means of estimating the viscoelastic properties of the foam. One unique advantage of the technique is the lack of interactions between the foam and container surfaces, which must be accounted for in other techniques. Results are presented in which a foam drop with gas volume fraction phi = 0.77 is levitated at 30 kHz and excited into its first quadrupole resonance at 63 +/- 3 Hz. By modeling the drop as an elastic sphere, the shear modulus of the foam was estimated at 75 +/- 3 Pa.

  8. Measurement of Aqueous Foam Rheology by Acoustic Levitation

    NASA Technical Reports Server (NTRS)

    McDaniel, J. Gregory; Holt, R. Glynn; Rogers, Rich (Technical Monitor)

    2000-01-01

    An experimental technique is demonstrated for acoustically levitating aqueous foam drops and exciting their spheroidal modes. This allows fundamental studies of foam-drop dynamics that provide an alternative means of estimating the viscoelastic properties of the foam. One unique advantage of the technique is the lack of interactions between the foam and container surfaces, which must be accounted for in other techniques. Results are presented in which a foam drop with gas volume fraction phi = 0.77 is levitated at 30 kHz and excited into its first quadrupole resonance at 63 +/- 3 Hz. By modeling the drop as an elastic sphere, the shear modulus of the foam was estimated at 75 +/- 3 Pa.

  9. Materials Applications for Non-Lethal: Aqueous Foams

    SciTech Connect

    GOOLSBY,TOMMY D.; SCOTT,STEVEN H.

    1999-09-15

    High expansion aqueous foam is an aggregation of bubbles that has the appearance of soap suds and is used to isolate individuals both visually and acoustically. It was developed in the 1920's in England to fight coal mine fires and has been widely used since for fire fighting and dust suppression. It was developed at Sandia National Laboratories (SNL) in the 1970's for nuclear safeguards and security applications. In the mid-1990s, the National Institute of Justice (NIJ), the research arm of the Department of Justice, began a project with SNL to determine the applicability of high expansion aqueous foam for correctional applications. NIJ funded the project as part of its search for new and better less-than-lethal weapons for responding to violent and dangerous individuals, where other means of force could lead to serious injuries. The phase one objectives of the project were to select a low-to-no toxicity foam concentrate (foaming agent) with physical characteristics suited for use in a single cell or large prison disturbances, and to determine if the selected foam concentrate could serve as a carrier for Oleoresin Capsicum (OC) irritant. The phase two objectives were to conduct an extensive toxicology review of the selected foam concentrate and OC irritant, and to conduct respiration simulation experiments in the selected high expansion aqueous foam. The phase three objectives were to build a prototype individual cell aqueous foam system and to study the feasibility of aqueous foams for large prison facility disturbances. The phase four and five objectives were to use the prototype system to do large scale foam physical characteristics testing of the selected foam concentrate, and to have the prototype single cell system further evaluated by correctional representatives. Prison rather than street scenarios were evaluated as the first and most likely place for using the aqueous foam since prisons have recurrent incidents where officers and inmates might be

  10. Foam Flows in Analog Porous Media

    NASA Astrophysics Data System (ADS)

    Meheust, Y.; Géraud, B.; Jones, S. A.; Cantat, I.; Dollet, B.

    2015-12-01

    Foams have been used for decades as displacing fluids for EOR and aquifer remediation, and more recently as carriers of chemical amendments for the remediation of the vadose zone. Apart from various interesting physico-chemical and biochemical properties, foams are better injection fluids due to their low sensitivity to gravity and their peculiar rheology: for foams with bubbles on the order of at least the typical pore size, viscous dissipation arises mostly from the contact zones between the soap films and the walls. In most experimental studies no local information of the foam structure is possible, and only global quantities such as the effective viscosity can be measured. We investigate foam flow through a two-dimensional porous medium consisting of circular obstacles positioned randomly in a horizontal transparent Hele-Shaw cell. The local foam structure is recorded in situ, which provides a measure of the spatial distribution of bubble velocities and sizes at regular time intervals. The flow exhibits a rich phenomenology including preferential flow paths and local flow intermittency/non-stationarity despite the imposed permanent global flow rate. Moreover, the medium selects the bubble size distribution through lamella division-triggered bubble fragmentation. Varying the mean bubble size of the injected foam, its water content, and mean velocity, we characterize those processes systematically and show that the distributions of bubble sizes and velocities are to some extent correlated. We furthermore measure the evolution, along the flow direction, of the distribution of bubble sizes, and measure the efficiency of bubble fragmentation as a function of the control parameters. The bubble fragmentation can be modeled numerically and to some extent analytically, based on statistical measures inferred from the experimental data. This study sheds new light on the local rheology of foams in porous media and opens the way towards quantitative characterization of the

  11. Flowing Foam: T1 events and solid-liquid transitions.

    NASA Astrophysics Data System (ADS)

    Dennin, Michael

    2005-11-01

    Flowing aqueous foam is found in many applications ranging from oil recovery, to fire fighting, to spreading shaving cream. Aqueous foam consists of gas bubbles with liquid walls. One of the striking features of foam is that despite being composed entirely of fluids, its mechanical properties are either those of a solid (elastic response) or fluid (viscous flow), depending on the nature of the applied stress and strains. We study the transition between these two regimes using a model foam system: bubble rafts. Bubble rafts are a single layer of bubbles floating on the air-water surface. This allows us to track the motion of all the bubbles during flow. In this talk, we will present two main results. First, we will discuss the observation of the coexistence between a solid-like and fluid-like state during flow. Second, we will discuss the role played by nonlinear, topological rearrangements, known as T1 events, in determining the mechanical response of the system.

  12. Capillary imbibition of aqueous foams by miscible and nonmiscible liquids

    NASA Astrophysics Data System (ADS)

    Mensire, Rémy; Piroird, Keyvan; Lorenceau, Elise

    2015-11-01

    When put in contact with a large liquid drop, dry foams wick owing to surface-tension-driven flows until reaching equilibrium. This work is devoted to the dynamics of this imbibition process. We consider imbibition of both wetting or nonwetting liquid, by putting the dry foam into contact either with the foaming solution that constitutes the foam or with organic oils. Indeed, with the appropriate choice of surfactants, oil spontaneously invades the liquid network of the foam without damaging it. Our experiments show an early-time dynamics in t1 /2 followed by a late-time dynamics in t1 /4. These features, which differ from theoretical works predicting a t1 /3 dynamics, are rationalized considering the influence of the initial liquid fraction of the foam in the driving capillary force and the impact of gravity through the capillary-gravity equilibrium.

  13. Surfactant- and Aqueous-Foam-Driven Oil Extraction from Micropatterned Surfaces.

    PubMed

    Mensire, Rémy; Wexler, Jason S; Guibaud, Augustin; Lorenceau, Elise; Stone, Howard A

    2016-12-13

    Liquid-infused surfaces are rough or patterned surfaces in which a lubricating fluid, such as oil, is infused, which exhibits various original properties (omniphobicity, biofouling, drag reduction). An outer flow in a confined geometry can entrain the oil trapped between the pattern of the surfaces by shearing the oil-water interface and cause the loss of the omniphobic properties of the interface. Starting from the theoretical analysis of Wexler et al. (Shear-driven failure of liquid-infused surfaces. Phys. Rev. Lett. 2015, 114, 168301), where a pure aqueous solution is the outer phase, we extend the predictions by introducing an extraction efficiency parameter α and by accounting for new dynamical effects induced by surfactants and aqueous foams. For surfactant solutions, decreasing the oil-water interfacial tension (γow) not only enhances oil extraction as expected but also modifies the dynamics of the receding oil-water interface through the variations of the receding contact angle (θ) with the capillary number (Ca), which is the ratio between the viscous and the capillary forces at the oil-water interface. For aqueous foams, the extraction dynamics are also influenced by the foam flow: oil is sheared by the thin film between the bubbles and the lubricating layer, which imposes a stronger interfacial shear compared to pure aqueous solutions. In both surfactant and foam cases, the experimental observations show the existence of nonuniform extraction dynamics related to the surfactant-induced instability of a two-fluid shear flow.

  14. Onset of flow instability in rigid foams

    NASA Astrophysics Data System (ADS)

    Barros Ochoa, Carlos Andrés; Denissenko, Petr; Duque Daza, Carlos Alberto

    2016-11-01

    The flow transition between stationary and time dependent regimes at the exit of a block of open-cell foam has been examined experimentally using Laser Doppler Anemometry. Measurements have been conducted at three points located at a plane located 10 mm downstream from the exit of the foam. The streamwise component of fluid velocity was measured at multiple flow rates. The probability density function of the velocity is two-peaked at Reynolds numbers above 25 based on the average pore size and is a skewed one-peak distribution at lower flow rates. Numerical simulations are being conducted using a computer tomography scanned model of the foam to match the experimental measurements. Obtained results are discussed in the context of using the open-cell foams in catalytic reactors.

  15. Aqueous foams stabilised solely by nanoparticles

    NASA Astrophysics Data System (ADS)

    Langevin, Dominique

    2011-03-01

    Particles are being increasingly used to stabilise foams and emulsions, the corresponding emulsions being known as ``Pickering'' emulsions. One of the peculiarities of these systems is the absence of Ostwald ripening: since the bubbles or drops do not grow (coalescence seems also suppressed) both foams and emulsions are stable over extremely long periods of time (months). These features make particles very interesting surface active agents as compared to standard surfactants or polymers/proteins. The origin of the suppression of ripening can be traced to the unusual behaviour of the interfacial layers made by these particles. The layers are solid-like and the usual characterisation methods (surface tension, surface rheology) are not straightforward to use. In this presentation, we will illustrate these difficulties with experiments made with partially hydrophobic silica nanoparticles. We will also discuss the relevance of foam characterisations methods such as multiple light scattering and X-ray tomography.

  16. Stable Aqueous Foams from Cellulose Nanocrystals and Methyl Cellulose.

    PubMed

    Hu, Zhen; Xu, Richard; Cranston, Emily D; Pelton, Robert H

    2016-12-12

    The addition of cellulose nanocrystals (CNC) greatly enhanced the properties of methylcellulose (MC) stabilized aqueous foams. CNC addition decreased air bubble size, initial foam densities and drainage rates. Mixtures of 2 wt % CNC + 0.5 wt % MC gave the lowest density foams. This composition sits near the onset of nematic phase formation and also near the overlap concentration of methylcellulose. More than 94% of the added CNC particles remained in the foam phase, not leaving with the draining water. We propose that the nanoscale CNC particles bind to the larger MC coils both in solution and with MC at the air/water interface, forming weak gels that stabilize air bubbles. Wet CNC-MC foams were sufficiently robust to withstand high temperature (70 °C for 6 h) polymerization of water-soluble monomers giving macroporous CNC composite hydrogels based on acrylamide (AM), 2-hydroxyethyl methacrylate (HEMA), or polyethylene glycol diacrylate (PEGDA). At high temperatures, the MC was present as a fibrillar gel phase reinforced by CNC particles, explaining the very high foam stability. Finally, our CNC-MC foams are based on commercially available forms of CNC and MC, already approved for many applications. This is a "shovel-ready" technology.

  17. Non-aqueous foams: Current understanding on the formation and stability mechanisms.

    PubMed

    Fameau, Anne-Laure; Saint-Jalmes, Arnaud

    2017-09-01

    The most common types of liquid foams are aqueous ones, and correspond to gas bubbles dispersed in an aqueous liquid phase. Non-aqueous foams are also composed of gas bubbles, but dispersed in a non-aqueous solvent. In the literature, articles on such non-aqueous foams are scarce; however, the study of these foams has recently emerged, especially because of their potential use as low calories food products and of their increasing importance in various other industries (such as, for instance, the petroleum industry). Non-aqueous foams can be based on three different foam stabilizers categories: specialty surfactants, solid particles and crystalline particles. In this review, we only focus on recent advances explaining how solid and crystalline particles can lead to the formation of non-aqueous foams, and stabilize them. In fact, as discussed here, the foaming is both driven by the physical properties of the liquid phase and by the interactions between the foam stabilizer and this liquid phase. Therefore, for a given stabilizer, different foaming and stability behavior can be found when the solvent is varied. This is different from aqueous systems for which the foaming properties are only set by the foam stabilizer. We also highlight how these non-aqueous foams systems can easily become responsive to temperature changes or by the application of light. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Quasi-steady model for predicting temperature of aqueous foams circulating in geothermal wellbores

    SciTech Connect

    Blackwell, B.F.; Ortega, A.

    1983-01-01

    A quasi-steady model has been developed for predicting the temperature profiles of aqueous foams circulating in geothermal wellbores. The model assumes steady one-dimensional incompressible flow in the wellbore; heat transfer by conduction from the geologic formation to the foam is one-dimensional radially and time-dependent. The vertical temperature distribution in the undisturbed geologic formation is assumed to be composed of two linear segments. For constant values of the convective heat-transfer coefficient, a closed-form analytical solution is obtained. It is demonstrated that the Prandtl number of aqueous foams is large (1000 to 5000); hence, a fully developed temperature profile may not exist for representative drilling applications. Existing convective heat-transfer-coefficient solutions are adapted to aqueous foams. The simplified quasi-steady model is successfully compared with a more-sophisticated finite-difference computer code. Sample temperature-profile calculations are presented for representative values of the primary parameters. For a 5000-ft wellbore with a bottom hole temperature of 375{sup 0}F, the maximum foam temperature can be as high as 300{sup 0}F.

  19. Surface cooling mechanism of fire suppression by aqueous foam

    NASA Astrophysics Data System (ADS)

    Conroy, Michael; Ananth, Ramagopal

    2013-03-01

    We investigate the ability of room-temperature foam to directly cool the surface of a liquid fuel pool at burning conditions and to reduce the fuel vapor pressure. We solve an unsteady, one-dimensional heat conduction equation using the finite element method to predict the temperature within an aqueous foam layer above a liquid fuel (heptane) layer. The sharp gradients in temperature and thermal properties at the foam-fuel interface are treated approximately inside of a thin interfacial layer above the fuel surface. We predict a rapid, significant reduction in the fuel surface temperature due to the large initial temperature gradient and the foam thermal diffusivity. The predicted surface cooling leads to a significant decrease in the fuel vapor pressure in less than a second. The mechanisms of fire suppression by aqueous foams are not well understood and the model predictions show that direct surface cooling could provide an important contribution to fire suppression. Experiments are in progress to quantify the surface cooling effect on heptane pool fire suppression.

  20. Stabilized aqueous foam systems and concentrate and method for making them

    DOEpatents

    Rand, Peter B.

    1984-01-01

    This invention comprises a combination of a water soluble polymer of the polyacrylic acid type, a foam stabilizer of dodecyl alcohol, a surfactant, a solvent and water as a concentrate for use in producing stabilized aqueous foams. In another aspect, the invention comprises a solution of the concentrate with water. In still another aspect the invention includes a method of generating stabilized aqueous foams.

  1. Capillary flow of oil in a single foam microchannel.

    PubMed

    Piroird, Keyvan; Lorenceau, Élise

    2013-12-06

    When using appropriate surfactants, oil and aqueous foam can be intimately mixed without the foam being destroyed. In this Letter, we show that a foam, initially free of oil, can draw an oil drop under the action of capillary forces and stretch it through the aqueous network. We focus on the suction of oil by a single horizontal foam channel, known as a Plateau border. In such confined channels, imbibition dynamics are governed by a balance between capillarity and viscosity. Yet, the scaling law for our system differs from that of classical imbibition in porous media such as aqueous foam. This is due to the particular geometry of the liquid channels: Plateau borders filled with foaming solution are always concave whereas they can be convex or flat when filled with oil. Finally, the oil slug, confined in the Plateau border, fragments into droplets following a film breakup.

  2. Coarse graining flow of spin foam intertwiners

    NASA Astrophysics Data System (ADS)

    Dittrich, Bianca; Schnetter, Erik; Seth, Cameron J.; Steinhaus, Sebastian

    2016-12-01

    Simplicity constraints play a crucial role in the construction of spin foam models, yet their effective behavior on larger scales is scarcely explored. In this article we introduce intertwiner and spin net models for the quantum group SU (2 )k×SU (2 )k, which implement the simplicity constraints analogous to four-dimensional Euclidean spin foam models, namely the Barrett-Crane (BC) and the Engle-Pereira-Rovelli-Livine/Freidel-Krasnov (EPRL/FK) model. These models are numerically coarse grained via tensor network renormalization, allowing us to trace the flow of simplicity constraints to larger scales. In order to perform these simulations we have substantially adapted tensor network algorithms, which we discuss in detail as they can be of use in other contexts. The BC and the EPRL/FK model behave very differently under coarse graining: While the unique BC intertwiner model is a fixed point and therefore constitutes a two-dimensional topological phase, BC spin net models flow away from the initial simplicity constraints and converge to several different topological phases. Most of these phases correspond to decoupling spin foam vertices; however we find also a new phase in which this is not the case, and in which a nontrivial version of the simplicity constraints holds. The coarse graining flow of the BC spin net models indicates furthermore that the transitions between these phases are not of second order. The EPRL/FK model by contrast reveals a far more intricate and complex dynamics. We observe an immediate flow away from the original simplicity constraints; however, with the truncation employed here, the models generically do not converge to a fixed point. The results show that the imposition of simplicity constraints can indeed lead to interesting and also very complex dynamics. Thus we need to further develop coarse graining tools to efficiently study the large scale behavior of spin foam models, in particular for the EPRL/FK model.

  3. Aqueous foams and foam films stabilised by surfactants. Gravity-free studies

    NASA Astrophysics Data System (ADS)

    Langevin, Dominique

    2017-01-01

    There are still many open questions and problems in both fundamental research and practical applications of foams. Despite the fact that foams have been extensively studied, many aspects of foam physics and chemistry still remain unclear. Experiments on foams performed under microgravity allow studying wet foams, such as those obtained early during the foaming process. On Earth, wet foams evolve too quickly due to gravity drainage and only dry foams can be studied. This paper reviews the foam and foam film studies that we have performed in gravity-free conditions. It highlights the importance of surface rheology as well as of confinement effects in foams and foam films behaviour.

  4. The flow of a foam in a two-dimensional porous medium

    NASA Astrophysics Data System (ADS)

    Géraud, Baudouin; Jones, Siân. A.; Cantat, Isabelle; Dollet, Benjamin; Méheust, Yves

    2016-02-01

    Foams have been used for decades as displacing fluids for enhanced oil recovery and aquifer remediation, and more recently, for remediation of the vadose zone, in which case foams carry chemical amendments. Foams are better injection fluids than aqueous solutions due to their low sensitivity to gravity and because they are less sensitive to permeability heterogeneities, thus allowing a more uniform sweep. The latter aspect results from their peculiar rheology, whose understanding motivates the present study. We investigate foam flow through a two-dimensional porous medium consisting of circular obstacles positioned randomly in a horizontal transparent Hele-Shaw cell. The local foam structure is recorded in situ, which provides a measure of the spatial distribution of bubble velocities and sizes at regular time intervals. The flow exhibits a rich phenomenology including preferential flow paths and local flow nonstationarity (intermittency) despite the imposed permanent global flow rate. Moreover, the medium selects the bubble size distribution through lamella division-triggered bubble fragmentation. Varying the mean bubble size of the injected foam, its water content, and mean velocity, we characterize those processes systematically. In particular, we measure the spatial evolution of the distribution of bubble areas, and infer the efficiency of bubble fragmentation depending on the various control parameters. We furthermore show that the distributions of bubble sizes and velocities are correlated. This study sheds new light on the local rheology of foams in porous media and opens the way toward quantitative characterization of the relationship between medium geometry and foam flow properties. It also suggests that large-scale models of foam flows in the subsurface should account for the correlation between bubble sizes and velocities.

  5. Patterns, Instabilities, Colors, and Flows in Vertical Foam Films

    NASA Astrophysics Data System (ADS)

    Yilixiati, Subinuer; Wojcik, Ewelina; Zhang, Yiran; Pearsall, Collin; Sharma, Vivek

    2015-03-01

    Foams find use in many applications in daily life, industry and biology. Examples include beverages, firefighting foam, cosmetics, foams for oil recovery and foams formed by pollutants. Foams are collection of bubbles separated by thin liquid films that are stabilized against drainage by the presence of surfactant molecules. Drainage kinetics and stability of the foam are strongly influenced by surfactant type, addition of particles, proteins and polymers. In this study, we utilize the thin film interference colors as markers for identifying patterns, instabilities and flows within vertical foam films. We experimentally study the emergence of thickness fluctuations near the borders and within thinning films, and study how buoyancy, capillarity and gravity driven instabilities and flows, are affected by variation in bulk and interfacial physicochemical properties dependent on the choice of constituents.

  6. Electrocatalytic hydrodechlorination of 4-chlorobiphenyl in aqueous solution using palladized nickel foam cathode.

    PubMed

    Yang, Bo; Yu, Gang; Shuai, Danmeng

    2007-04-01

    The electrocatalytic hydrodechlorination of 4-chlorobiphenyl on palladized nickel foam with high porous structure in an aqueous solution containing MeOH, bromide of hexadecyltrimethylammonium (CTAB), sodium acetate, and acetic acid were investigated in a membrane-separated flow-through cell. The Pd/Ni foam electrode was prepared by electroless deposition method, on which the Pd particles dispersed finely over Ni foam surface indicated by SEM-EDX analysis. The effects of current density, organic cosolvent, initial concentration, temperature, and flow rate on the hydrodechlorination of 4-chlorobiphenyl were examined. Methanol was among the best cosolvents and was used in preferential concentration of 50 vol%. Moderate current density (e.g., 2.23 mA cm(-2)), relatively high initial concentration, temperature, and flow rate were beneficial to improve the hydrodechlorination of 4-chlorobiphenyl. The current efficiencies for the conversion of 1mM 4-MCB decreased with increasing current density and range from 37.2% at 0.74 mA cm(-2) to 14.1% at 5.21 mA cm(-2) after 20 min electrolysis cut. Under the optimized conditions, 1mM of 4-MCB could be removed rapidly with the rate of 94.6% after 2h electrolysis, which gave current efficiencies and energy consumptions in range of 8.1-24.6% and 1.7-5.2 kW h kg(-1), respectively.

  7. Transient foam flow in porous media with CAT Scanner

    SciTech Connect

    Liu, Dianbin; Brigham, W.E.

    1992-03-01

    Transient behavior is likely to dominate over most of the duration of a foam injection field project. Due to the lack of date, little is presently known about transient foam flow behavior. Foam flow does not follow established models such as the Buckley-Leverett theory, and no general predictive model has been derived. Therefore, both experimental data and a foam flow theory are needed. In this work, foam was injected at a constant mass rate into one-dimensional sandpacks of 1-in diameter and 24-in or 48-in length that had initially been saturate with distilled water. The system was placed in a cat Scanner. Data, obtained at room temperature and low pressure at various times, include both the pressure and saturation distributions. Pressure profiles showed that the pressure gradient is much greater behind the foam front than ahead of it. Moreover, the pressure gradients keep changing as the foam advances in the sandpack. This behavior differs from Buckley-Leverett theory. The CT scan results demonstrated gas channeling near the front, but eventually the foam block all these channels and sweeps the entire cross section after many pore volumes of injection. Three series of experiments were run: (1) surfactant adsorption measurements; (2) gas displacements of surfactant-laden solutions and (3) foam displacements. The first two series of experiments were made to provide the necessary parameters required to match the foam displacements. To this end, it was necessary to smooth the saturation history data, using a Langmuir-type formula. A theory was proposed based on the principles of the fractional flow curve construction method. This foam theory treats the foam as composed of infinitesimal slugs of gas of varying viscosities. The foam front has the lowest viscosity and foam at the injection end has the highest.

  8. Sonochemical degradation of perfluorooctanesulfonate in aqueous film-forming foams.

    PubMed

    Vecitis, Chad D; Wang, Yajuan; Cheng, Jie; Park, Hyunwoong; Mader, Brian T; Hoffmann, Michael R

    2010-01-01

    Aqueous film-forming foams (AFFFs) are fire extinguishing agents developed by the Navy to quickly and effectively combat fires occurring close to explosive materials and are utilized today at car races, airports, oil refineries, and military locations. Fluorochemical (FC) surfactants represent 1-5% of the AFFF composition, which impart properties such as high spreadability, negligible fuel diffusion, and thermal stability to the foam. FC's are oxidatively recalcitrant, persistent in the environment, and have been detected in groundwater at AFFF training sites. Ultrasonic irradiation of aqueous FCs has been reported to degrade and subsequently mineralize the FC surfactants perfluorooctanoate (PFOA) and perfluorooctanesulfonate (PFOS). Here we present results of the sonochemical degradation of aqueous dilutions of FC-600, a mixture of hydrocarbon (HC) and fluorochemical components including cosolvents, anionic hydrocarbon surfactants, fluorinated amphiphilic surfactants, anionic fluorinated surfactants, and thickeners such as starch. The primary FC surfactant in FC-600, PFOS, was sonolytically degraded over a range of FC-600 aqueous dilutions, 65 ppb < [PFOS]i < 13100 ppb. Sonochemical PFOS-AFFF decomposition rates, RAFFF-PFOS, are similar to PFOS-Milli-Q rates, RMQ-PFOS, indicating that the AFFF matrix only had a minor effect on the sonochemical degradation rate, 0.5 < RAFFF-PFOS/RMQ-PFOS < 2.0, even though the total organic concentration was 50 times the PFOS concentration, [Org]tot/[PFOS] 50, consistent with the superior FC surfactant properties. Sonochemical sulfate production is quantitative, delta[SO42-]/delta[PFOS] > or = 1, indicating that bubble-water interfacial pyrolytic cleavage of the C-S bond in PFOS is the initial degradation step, in agreement with previous studies done in Milli-Q water. Sonochemical fluoride production is significantly below quantitative expectations, delta[F-]/delta[PFOS] 4 vs 17, suggesting that in the AFFF matrix, PFOS

  9. Flow of foam through a convergent channel.

    PubMed

    Dollet, Benjamin; Bocher, Claire

    2015-11-01

    We study experimentally the flow of a foam confined as a bubble monolayer between two plates through a convergent channel. We quantify the velocity, the distribution and orientation of plastic events, and the elastic stress, using image analysis. We use two different soap solutions: a sodium dodecyl sulfate (SDS) solution, with a negligible wall friction between the bubbles and the confining plates, and a mixture containing a fatty acid, giving a large wall friction. We show that for SDS solutions, the velocity profile obeys a self-similar form which results from the superposition of plastic events, and the elastic deformation is uniform. For the other solution, the velocity field differs and the elastic deformation increases towards the exit of the channel. We discuss and quantify the role of wall friction on the velocity profile, the elastic deformation, and the rate of plastic events.

  10. Material flow in metal foams studied by neutron radioscopy

    NASA Astrophysics Data System (ADS)

    Stanzick, H.; Klenke, J.; Danilkin, S.; Banhart, J.

    Two kinds of experiments are presented in this paper: In the first lead alloy foams were generated in a furnace by expanding a foamable precursor material containing metal and a blowing agent. Vertical columns of liquid metal foam were scanned with a beam of neutrons while recording the time-dependent local neutron transmission. The resulting transmission profiles reflect the kinetics of material redistribution in liquid metallic foams under the influence of gravity (drainage). In the second experiment pre-fabricated solid lead foams were re-melted in a furnace. Neutron transmission profiles were also obtained in these experiments. Results of each type of experiment are presented and compared with theoretical predictions for the density profile of aqueous foams.

  11. Ultradry Carbon Dioxide-in-Water Foams with Viscoelastic Aqueous Phases.

    PubMed

    Xue, Zheng; Worthen, Andrew J; Da, Chang; Qajar, Ali; Ketchum, Isaiah Robert; Alzobaidi, Shehab; Huh, Chun; Prodanović, Maša; Johnston, Keith P

    2016-01-12

    For foams with ultra low water contents, the capillary pressure is very large and induces rapid drainage that destabilizes the aqueous lamellae between the gas bubbles. However, we show that high-pressure CO2-in-water foams can be stabilized with a viscoelastic aqueous phase composed of entangled wormlike micelles, even for extremely high CO2 volume fractions ϕ of 0.95 to 0.98; the viscosity of these ultradry foams increased by up to 3-4-fold, reaching more than 100 cP relative to foams formed with conventional low viscosity aqueous phases. The foam morphology consisted of fine ∼20 μm polyhedral-shaped CO2 bubbles that were stable for hours. The wormlike micelles were formed by mixing anionic sodium lauryl ether sulfate (SLES) with salt and a protonated cationic surfactant, as shown by cryogenic transmission electron microscopy (cryo-TEM) and large values of the zero-shear viscosity and the dynamic storage and loss moduli. With the highly viscous continuous aqueous phases, the foam lamella drainage rates were low, as corroborated by confocal microscopy. The preservation of viscous thick lamellae resulted in lower rates of Ostwald ripening relative to conventional foams as shown by high-pressure optical microscopy. The ability to stabilize viscous ultra high internal phase foams is expected to find utility in various practical applications, including nearly "waterless" fracturing fluids for recovery of oil and gas in shale, offering the possibility of a massive reduction in the amount of wastewater.

  12. Electrochemical dechlorination of chloroform in neutral aqueous solution on palladium/foam-nickel and palladium/polymeric pyrrole film/foam-nickel electrodes.

    PubMed

    Sun, Zhirong; Li, Baohua; Hu, Xiang; Shi, Min; Hou, Qingnan; Peng, Yongzhen

    2008-01-01

    Electrochemical dechlorination of chloroform in neutral aqueous solution was investigated using palladium-loaded electrodes at ambient temperature. Palladium/foam-nickel (Pd/foam-Ni) and palladium/polymeric pyrrole film/foam-nickel (Pd/PPy/foam-Ni) composite electrodes which provided catalytic surface for reductive dechlorination of chloroform in aqueous solution were prepared using an electrodepositing method. Scanning electron microscope (SEM) micrographs showed that polymeric pyrrole film modified the electrode-surface characteristics and resulted in the uniform dispersion of needle-shaped palladium particles on foam-Ni supporting electrode. The experimental results of dechlorination indicated that the removal efficiency of chloroform and current efficiency in neutral aqueous solution on Pd/PPy/foam-Ni electrode could be up to 36.8% and 33.0% at dechlorination current of 0.1 mA and dechlorination time of 180 min, which is much higher than that of Pd/foam-Ni electrode.

  13. Aqueous foams: a field of investigation at the frontier between chemistry and physics.

    PubMed

    Langevin, Dominique

    2008-03-14

    This paper reviews the properties of aqueous foams. The current state of knowledge is summarized briefly and the interdisciplinary aspects of this field of investigation are emphasized. Many phenomena are controlled by physical laws, but they are highly dependent upon the chemicals used as foam stabilizers: surfactants, polymers, particles. Most of the existing work is related to surfactants and polymer foams, and little is known yet for particle foams although research in this field is becoming popular. This article presents the general concepts used to describe the monolayers and the films and also some of the recent advances being made in this area.

  14. A population balance model for transient and steady-state foam flow in Boise sandstone

    SciTech Connect

    Kovscek, A.; Patzek, T.; Radke, C.

    1995-07-01

    An experimental and mechanistic-modeling study is reported for the transient flow of aqueous foam through 1.3-{mu}m{sup 2} (1.3-D) Boise sandstone at backpressures in excess of 5 MPa (700 psi) over a quality range from 0.80 to 0.99. Total superficial velocities range from as little as 0.42 to 2.20 m/day (1.4 ft/day to 7 ft/day). Sequential pressure taps and gamma-ray densitometry measure flow resistance and in-situ liquid saturations, respectively. We garner experimental pressure and saturation profiles in both the transient and steady states. Adoption of a mean-size foam-bubble conservation equation along with the traditional reservoir simulation equations allows mechanistic foam simulation. Since foam mobility depends heavily upon its texture, the bubble population balance is both useful and necessary as the role of foam texture must be incorporated into any model which seeks accurate prediction of flow properties. Our model employs capillary-pressure-dependent kinetic expressions for lamellae generation and coalescence and also a term for trapping of lamellae. Additionally, the effects of surfactant chemical transport are included. We find quantitative agreement between experimental and theoretical saturation and pressure profiles in both the transient and steady states.

  15. Aqueous foam as a less-than-lethal technology for prison applications

    NASA Astrophysics Data System (ADS)

    Goolsby, Tommy D.

    1997-01-01

    High expansion aqueous foam is an aggregation of bubbles that has the appearance of soap suds and is used to isolate individuals both visually and acoustically. It was developed in the 1920's in England to fight coal mine fires and has been widely used since for fire fighting and dust suppression. It was developed at Sandia National Laboratories (SNL) in the 1970's for nuclear safeguards and security applications. In late 1994, the National Institute of Justice (NIJ), the research arm of the Department of Justice, began a project with SNL to determine the applicability of high expansion aqueous foam for correctional applications. NIJ funded the project as part of its search for new and better less-than-lethal weapons for responding to violent and dangerous individuals, where other means of force could lead to serious injuries. The phase one objectives of the project were to select a low-to-no toxicity foam concentrate with physical characteristics suited for use in a single cell or large prison disturbances, and to determine if the selected foam concentrate could serve as a carrier for Oleoresin Capsicum (OC) irritant. The phase two objective were to conduct an extensive toxicology review of the selected foam concentrate and OC irritant, and to conduct respiration simulation experiments in the selected high expansion aqueous foam. The phase three objectives were to build a prototype individual cell aqueous foam system and to study the feasibility of aqueous foams for large prison facility disturbances. The phase four and five objectives were to use the prototype system to do large scale foam physical characteristics testing of the selected foam concentrate, and to have the prototype single cell system further evaluated by correctional representatives. Prison rather than street scenarios were evaluated as the first and most likely place for using the aqueous foam since prisons have recurrent incidents where officers and inmates might be seriously injured during

  16. Study of Polyurethane Foaming Dynamics Using a Heat Flow Meter

    NASA Astrophysics Data System (ADS)

    Koniorczyk, P.; Trzyna, M.; Zmywaczyk, J.; Zygmunt, B.; Preiskorn, M.

    2017-05-01

    This work presents the results of the study concerning the effects of fillers addition on the heat flux density \\dot{q}( t ) of foaming of polyurethane-polystyrene porous composite (PSUR) and describes the dynamics of this process during the first 600 s. This foaming process resulted in obtaining porous materials that were based on HFC 365/225 blown rigid polyurethane foam (PUR) matrix, which contained thermoplastic expandable polystyrene (EPS) beads as the filler. In PSUR composites, the EPS beads were expanded after being heated to a temperature above the glass transition temperature of EPS and vaporing gas incorporated inside, by using the heat of exothermic reaction of polyol with isocyanate. From the start (t=0) to the end of the PSUR composite foaming process (t=tk), \\dot{q}( t ) was measured with the use of the heat flow meter. For the purpose of the study two PUR systems were selected: one with high and one with low heat density of foaming process q. EPS beads were selected from the same manufacturer with large and small diameter. The mass fraction of EPS in PSUR foam varied during the measurements. Additionally, a study of volume fractions of expanded EPS phase in PSUR foams as a function of mass fractions of EPS was conducted. In order to verify effects of the EPS addition on the heat flux density during PSUR foaming process, the thermal conductivity measurements were taken.

  17. Thermal dispersion in vertical gas-liquid flows with foaming and non-foaming liquids

    SciTech Connect

    Pino, L.R.Z.; Saez, A.E.

    1995-05-01

    Heat transfer experiments have been performed in gas-liquid upwards flow in a vertical column with non-foaming (water) and foaming (kerosene) liquids. The main purpose of the experiments has been to characterized the degree of thermal mixing in the system. For the range of conditions employed, the nonfoaming liquid exhibits complete mixing a low liquid superficial velocities. An increased in liquid velocity leads to incomplete mixing. In the latter case, the thermal dispersion coefficient at low gas superficial velocities is larger than what correlations in the literature predict. For the foaming liquid, when foaming and bubbling regions coexist in the bubble column, each region behaves as a completely-mixed subsystem.

  18. Foam rheology: A model of viscous effects in shear flow

    NASA Astrophysics Data System (ADS)

    Kraynik, Andrew M.; Reinelt, Douglas A.

    Foams consisting of gas bubbles dispersed in a continuous network of thin liquid films display a remarkable range of rheological characteristics that include a finite shear modulus, yield stress, non-Newtonian viscosity, and slip at the wall. Progress in developing micromechanical theories to describe foam rheology has depended upon two-dimensional models, which in most cases are assumed to have perfectly ordered structure. Princen accounted for surface tension and geometrical effects, and analyzed the nonlinear elastic response of a spatially periodic foam in simple shear. His analysis has been extended to account for more general deformations. Khan and Armstrong and Kraynik and Hansen have proposed ad hoc models for viscous effects in foam rheology. Their models capture numerous qualitative phenomena but incorporate relaxation mechanisms based upon overly simplified assumptions of liquid flow in the thin films. Mysels, Shinoda, and Frankel considered soap films with interfaces that are inextensible due to the presence of surfactants. They analyzed the primary flow that occurs when such films are slowly withdrawn from or recede into essentially static junction regions such as the Plateau borders in a foam. Adopting this mechanism, Schwartz and Princen considered small periodic deformations of a foam and calculated the energy dissipation due to viscous flow in the thin films. In the following, we also adopt the basic interfacial and viscous mechanisms introduced by Mysels et al. and analyze simple shearing deformations of finite amplitude. The configuration and effective stress of the foam are determined. Under these deformation conditions, the foam is a nonlinear viscoelastic material. Results for the uniform expansion of a foam are also presented.

  19. Flow of foams in two-dimensional disordered porous media

    NASA Astrophysics Data System (ADS)

    Dollet, Benjamin; Geraud, Baudouin; Jones, Sian A.; Meheust, Yves; Cantat, Isabelle; Institut de Physique de Rennes Team; Geosciences Rennes Team

    2015-11-01

    Liquid foams are a yield stress fluid with elastic properties. When a foam flow is confined by solid walls, viscous dissipation arises from the contact zones between soap films and walls, giving very peculiar friction laws. In particular, foams potentially invade narrow pores much more efficiently than Newtonian fluids, which is of great importance for enhanced oil recovery. To quantify this effect, we study experimentally flows of foam in a model two-dimensional porous medium, consisting of an assembly of circular obstacles placed randomly in a Hele-Shaw cell, and use image analysis to quantify foam flow at the local scale. We show that bubbles split as they flow through the porous medium, by a mechanism of film pinching during contact with an obstacle, yielding two daughter bubbles per split bubble. We quantify the evolution of the bubble size distribution as a function of the distance along the porous medium, the splitting probability as a function of bubble size, and the probability distribution function of the daughter bubbles. We propose an evolution equation to model this splitting phenomenon and compare it successfully to the experiments, showing how at long distance, the porous medium itself dictates the size distribution of the foam.

  20. Drainage dynamics of aqueous foams generated by sparging and turbulent mixing

    NASA Astrophysics Data System (ADS)

    Kennedy, Matthew J.; Conroy, Michael W.; Ananth, Ramagopal; Fleming, James W.

    2012-02-01

    We investigate the effect of bubble size on the drainage dynamics of aqueous fire-suppression foams using laboratory-scale foam generators and theoretical modeling. We generate foams over a wide range of bubble sizes using two foam generation methods--sparging using fritted sheets of steel, and turbulent mixing using high-pressure T-junctions. The sparged foams comprise bubbles of mean diameter 0.5 mm or larger and begin draining immediately whereas the turbulently mixed foams comprise bubbles of mean diameter 0.15 mm or smaller and begin draining after induction times of 5-15 minutes. We study two proprietary fire-suppression foam solutions: a non-fluorinated surfactant solution containing viscous xantham gum intended for use as a wet foam, i.e. liquid fraction > 0.1, and a sodium dodecyl sulfate surfactant solution intended for use as a dry foam, i.e. liquid fraction < 0.005. The change in liquid retention time due to change in mean bubble size differs between these two solutions. We compare our experimental results with theoretical models to examine the reasons for the difference in liquid retention time.

  1. Aqueous particulate foams stabilized solely with polymer latex particles.

    PubMed

    Fujii, S; Iddon, P D; Ryan, A J; Armes, S P

    2006-08-29

    In this article, a wide range of latexes are evaluated as possible foam stabilizers. These include near-monodisperse, poly(N-vinyl pyrrolidone)-stabilized polystyrene [PNVP-PS] latexes with diameters ranging from 170 nm to 1.62 microm, submicrometer-sized poly(ethylene glycol)-stabilized polystyrene [PEGMA-PS] latex particles, a PNVP-stabilized poly(4-bromostyrene) [PNVP-PBrS] latex with a mean diameter of 870 nm, two PNVP-stabilized poly(methyl methacrylate) [PNVP-PMMA] latexes with mean diameters of 730 nm and 1.20 microm, a PNVP-stabilized poly(2-hydroxypropyl methacrylate) [PNVP-PHPMA] latex with a mean diameter of 630 nm, and a charge-stabilized anionic PS latex of 220 nm diameter. The effect of varying the particle size, latex concentration, and latex surface composition on foam stability were studied in detail. The larger PNVP-PS latexes, the PNVP-PBrS, and the two PNVP-PMMA latexes gave highly stable foams, whereas PEGMA-PS, PNVP-PHPMA, and the charge-stabilized PS latex produced either no foams or foams with inferior long-term stabilities. Scanning electron microscopy studies revealed hexagonally close-packed latex arrays in the walls of the dried foam, which leads to localized moiré patterns being observed by optical microscopy. Moreover, these dried foams are highly iridescent in bright transmitted light.

  2. Graphene oxide/chitin nanofibril composite foams as column adsorbents for aqueous pollutants.

    PubMed

    Ma, Zhongshi; Liu, Dagang; Zhu, Yi; Li, Zehui; Li, Zhenxuan; Tian, Huafeng; Liu, Haiqing

    2016-06-25

    A novel graphene oxide/chitin nanofibrils (GO-CNF) composite foam as a column adsorbent was prepared for aqueous contaminant disposal. The structures, morphologies and properties of composite foams supported by nanofibrils were characterized. As a special case, the adsorption of methylene blue (MB) on GO-CNF was investigated regarding the static adsorption and column adsorption-desorption tests. Results from equilibrium adsorption isotherms indicated that the adsorption behavior was well-fitted to Langmuir model. The composite foams reinforced by CNF were dimensionally stable during the column adsorption process and could be reused after elution. The removal efficiency of MB was still nearly 90% after 3 cycles. Furthermore, other inorganic or organic pollutants adsorbed by composite foams were also explored. Therefore, this novel composite foam with remarkable properties such as dimensional stability, universal adsorbent for cationic pollutants, high adsorption capacity, and ease of regeneration was a desirable adsorbent in the future practical application of water pollutant treatment.

  3. Stable 'arrested' non-aqueous edible foams based on food emulsifiers.

    PubMed

    Patel, A R

    2017-06-21

    Stable oil foams with structured air-oil interfaces and high overrun (φair ≫ 0.5) were fabricated using edible emulsifiers (sucrose esters and lecithin). Advanced microscopy was used to understand the microstructure of these 'arrested' non-aqueous foams which displayed interesting rheological behaviour (yielding and thixotropy). Such complex colloids stabilized by edible ingredients could find important industrial applications in the development of novel textured food products.

  4. A Porous Media Model for Blood Flow within Reticulated Foam

    PubMed Central

    Ortega, J.M.

    2013-01-01

    A porous media model is developed for non-Newtonian blood flow through reticulated foam at Reynolds numbers ranging from 10−8 to 10. This empirical model effectively divides the pressure gradient versus flow speed curve into three regimes, in which either the non-Newtonian viscous forces, the Newtonian viscous forces, or the inertial fluid forces are most prevalent. When compared to simulation data of blood flow through two reticulated foam geometries, the model adequately captures the pressure gradient within all three regimes, especially that within the Newtonian regime where blood transitions from a power-law to a constant viscosity fluid. PMID:24031095

  5. Pore level visualization of foam flow in a silicon micromodel. SUPRI TR 100

    SciTech Connect

    Woody, F.; Blunt, M.; Castanier, L.

    1996-01-01

    This paper is concerned with the behavior of foam in porous media at the pore level. Identical, heterogeneous silicon micromodels, two dimensionally etched to replicate flow in Berea Sandstone, were used. The models, already saturated with varying concentrations of surfactant and, at times, oil were invaded with air. Visual observations were made of these air displacement events in an effort to determine foam flow characteristics with varying surfactant concentrations, and differing surfactants in the presence of oil. These displacement events were recorded on video tape. These tapes are available at the Stanford University Petroleum Research Institute, Stanford, California. The observed air flow characteristics can be broadly classified into two: continuous and discontinuous. Continuous air flow was observed in two phase runs when the micromodel contained no aqueous surfactant solution. Air followed a tortuous path to the outlet, splitting and reconnecting around grains, isolating water located in dead-end or circumvented pores, all without breaking and forming bubbles. No foam was created. Discontinuous air flow occurred in runs containing surfactant - with smaller bubble sizes appearing with higher surfactant concentrations. Air moved through the medium by way of modified bubble train flow where bubbles travel through pore throats and tend to reside more statically in larger pore bodies until enough force is applied to move them along. The lamellae were stable, and breaking and reforming events by liquid drainage and corner flow were observed in higher surfactant concentrations. However, the classic snap-off process, as described by Roof (1973) was not seen at all.

  6. Iridescent Patterns and Flows in Vertical Foam Films

    NASA Astrophysics Data System (ADS)

    Wojcik, Ewelina; Yilixiati, Subinuer; Abbott-Klostermann, Will; Sharma, Vivek

    2015-03-01

    Liquid foams consist of bubbles separated by thin films. Individual films consist of two surfactant-laden surfaces that are ~ 5 nm - 10 micron apart. Sandwiched between these interfacial layers is a fluid that drains primarily under the influence of gravitational, viscous and interfacial forces, including disjoining pressure. Understanding and controlling the drainage kinetics of thin films is an important problem that underlies the stability, lifetime and rheology of foams and emulsions. We experimentally follow the drainage kinetics of foam films using imaging & color science. Interference between light reflected from two surfactant-laden surfaces that are ~ 100 nm - 10 micron apart leads to thickness-dependent iridescent colors in the visible region. Below 50 nm the thin films appear as black. We find fascinating examples of two-dimensional hydrodynamics and unexplained, if not unprecedented, drainage kinetics. In particular, we study the origin of marginal regeneration, i. e. the complex flow patterns that originate near the borders of foam films.

  7. Enhanced Amendment Delivery to Subsurface Using Shear Thinning Fluid and Aqueous Foam for Metal, Radionuclide, and NAPL Remediation

    NASA Astrophysics Data System (ADS)

    Zhong, L.; Szecsody, J.; Li, X.; Oostrom, M.; Truex, M.

    2010-12-01

    In many contamination sites, removal of contaminants by any active remediation efforts is not practical due to the high cost and technological limitations. Alternatively, in situ remediation is expected to be the most important remediation strategy. Delivery of reactive amendment to the contamination zone is essential for the reactions between the contaminants and remedial amendments to proceed in situ. It is a challenge to effectively deliver remedial amendment to the subsurface contamination source areas in both aquifer and vadose zone. In aquifer, heterogeneity induces fluid bypassing the low-permeability zones, resulting in certain contaminated areas inaccessible to the remedial amendment delivered by water injection, thus inhibiting the success of remedial operations. In vadose zone in situ remediation, conventional solution injection and infiltration for amendment delivery have difficulties to achieve successful lateral spreading and uniform distribution of the reactive media. These approaches also tend to displace highly mobile metal and radionuclide contaminants such as hexavalent chromium [Cr(VI)] and technetium (Tc-99), causing spreading of contaminations. Shear thinning fluid and aqueous foam can be applied to enhance the amendment delivery and improve in situ subsurface remediation efficiency under aquifer and vadose zone conditions, respectively. Column and 2-D flow cell experiments were conducted to demonstrate the enhanced delivery and improved remediation achieved by the application of shear thinning fluid and foam injection at the laboratory scale. Solutions of biopolymer xanthan gum were used as the shear thinning delivering fluids. Surfactant sodium lauryl ether sulfate (STEOL CS-330) was the foaming agent. The shear thinning fluid delivery (STFD) considerably improved the sweeping efficiency over a heterogeneous system and enhanced the non-aqueous liquid phase (NAPL) removal. The delivery of amendment into low-perm zones (LPZs) by STFD also

  8. Dispersion behavior and aqueous foams in mixtures of a vesicle-forming surfactant and edible nanoparticles.

    PubMed

    Binks, Bernard P; Campbell, Shawn; Mashinchi, Saeed; Piatko, Michael P

    2015-03-17

    In an attempt to prepare ultrastable aqueous foams composed entirely of food-grade ingredients, we describe the foamability and foam stability of aqueous phases containing either calcium carbonate particles (CaCO3), sodium stearoyl lactylate surfactant (SSL), or their mixtures. Techniques including zeta potential measurements, adsorption isotherm determination, contact angles and optical and cryo-scanning electron microscopy are used to probe the interaction between particles and surfactant molecules. Aqueous dispersions of inherently hydrophilic cationic CaCO3 nanoparticles do not foam to any great extent. By contrast, aqueous dispersions of anionic SSL, which forms a lamellar phase/vesicles, foam progressively on increasing the concentration. Despite their foamability being low compared to that of micelle-forming surfactant sodium dodecyl sulfate, they are much more stable to collapse with half-lives (of up to 40 days) of around 2 orders of magnitude higher above the respective aggregation concentrations. We believe that, in addition to surfactant lamellae around bubbles, the bilayers within vesicles contain surfactant chains in a solidlike state yielding indestructible aggregates that jam the aqueous films between bubbles, reducing the drainage rate and both bubble coalescence and gas-transfer between bubbles. In mixtures of particles and surfactant, the adsorption of SSL monomers occurs on particle surfaces, leading to an increase in their hydrophobicity, promoting particle adsorption to bubble surfaces. Ultrastable foams result with half-lives of around an order of magnitude higher again at low concentrations and foams which lose only around 30% of their volume within a year at high concentrations. In the latter case, we evidence a high surface density of discrete surfactant-coated particles at bubble surfaces, rendering them stable to coalescence and disproportionation.

  9. The research of press drop of compressed air foam flow through the bend

    NASA Astrophysics Data System (ADS)

    Chen, Y.; Chen, T.; Hu, C.; Fu, X. C.; Bao, Z. M.; Zhang, X. Z.; Xia, J. J.

    2017-08-01

    Compressed air foam system (CAFS) had obvious advantages in engineering. The flow model of compressed air foam in the pipeline was different from water flow model because the foam was the gas-liquid two phase flow with non-Newtonian fluid properties and compressibility, and, the water supply theory was not suitable for foam press pipeline transport. At present, there was little research on non-Newtonian fluid flow, especially the foam flow. This study researched the effect of foam flux, end valve and foam type on the press in the straight pipe and bend. The press drop in straight pipes and bends filled with compressed air foam was analyzed, and the result could provide experimental support for theoretical calculation of compressed air foam in bend.

  10. Blast wave mitigation by dry aqueous foam: numerical modelling and experimental investigation

    NASA Astrophysics Data System (ADS)

    Counilh, Denis; Ballanger, Felix; Rambert, Nicolas; Haas, Jean-Francois; Chinnayya, Aschwin; Lefrancois, Alexandre

    2016-11-01

    Dry aqueous foams (two-phase media with water liquid fraction lower than 5%) are known to mitigate blast wave effects induced by an explosion. The CEA has calibrated his numerical multiphase code MOUSSACA from shock tube and high-explosive experiments. The shock tube experiments have highlighted the foam fragmentation into droplets and the momentum transfer between the liquid and gas phases of the foam. More recently, experiments with hemispheric explosive charges from 3 g to 120 g have provided more findings about the pressure and impulse mitigation properties of foams. We have also taken into account the heat and mass transfer, as well as the droplets secondary breakup, characterized by the Weber number, ratio of inertia over surface tension. Good agreement is found between the calculation and the experiments. co-supervisor of the Felix Ballanger 's doctoral thesis.

  11. Patterns, Instabilities, Colors, and Flows in Vertical Foam Films

    NASA Astrophysics Data System (ADS)

    Yilixiati, Subinuer; Zhang, Yiran; Wojcik, Ewelina; Sharma, Vivek

    Understanding and controlling the drainage kinetics of thin films is an important problem that underlies the stability, lifetime and rheology of foams and emulsions. We follow the drainage kinetics of vertical foam films using imaging and color science. Interference between light reflected from two surfactant-laden surfaces that are 100 nm - 10 micron apart leads to thickness-dependent iridescent colors in the visible region. Below 50 nm the thin films appear as black. In this study, we utilize the thin film interference colors as markers for identifying patterns, instabilities and flows within vertical foam films. We study the emergence of thickness fluctuations near the borders (i.e. marginal regeneration) and within thinning films. Finally, we elucidate how buoyancy, capillarity, convection and gravity-driven instabilities and flows, are affected by the choice and concentration of constituents. We find fascinating examples of two-dimensional hydrodynamics and unexplained, if not unprecedented, drainage kinetics.

  12. Patterns, Instabilities, Colors, and Flows in Vertical Foam Films

    NASA Astrophysics Data System (ADS)

    Yilixiati, Subinuer; Wojcik, Ewelina; Zhang, Yiran; Shah, Krupa; Sharma, Vivek

    2015-11-01

    Understanding and controlling the drainage kinetics of thin films is an important problem that underlies the stability, lifetime and rheology of foams and emulsions. We follow the drainage kinetics of vertical foam films using imaging and color science. Interference between light reflected from two surfactant-laden surfaces that are 100 nm - 10 micron apart leads to thickness-dependent iridescent colors in the visible region. Below 50 nm the thin films appear as black. In this study, we utilize the thin film interference colors as markers for identifying patterns, instabilities and flows within vertical foam films. We study the emergence of thickness fluctuations near the borders (i.e. marginal regeneration) and within thinning films. Finally, we elucidate how buoyancy, capillarity, convection and gravity-driven instabilities and flows, are affected by the choice and concentration of constituents. We find fascinating examples of two-dimensional hydrodynamics and unexplained, if not unprecedented, drainage kinetics.

  13. pH-responsive aqueous foams stabilized by ionizable latex particles.

    PubMed

    Binks, Bernard P; Murakami, Ryo; Armes, Steven P; Fujii, Syuji; Schmid, Andreas

    2007-08-14

    We have designed a type of colloidal particle whose surface characteristics are sensitive to the pH of the aqueous phase in which they are dispersed. Particles of polystyrene latex stabilized by poly(acrylic acid) can act as stabilizers of aqueous foams by adsorbing at the air-water surface. Foams can be prepared and stabilized only at pH values below the isoelectric point where particles are either uncharged and flocculated or acquire a positive charge. At high pH where particles are anionic, no foam forms. This influence of pH on foamability and stability applies to both pH-dependent and pH-responsive systems.

  14. Fundamental investigation of foam flow in a liquid-filled Hele-Shaw cell.

    PubMed

    Osei-Bonsu, Kofi; Shokri, Nima; Grassia, Paul

    2016-01-15

    The relative immobility of foam in porous media suppresses the formation of fingers during oil displacement leading to a more stable displacement which is desired in various processes such as Enhanced Oil Recovery (EOR) or soil remediation practices. Various parameters may influence the efficiency of foam-assisted oil displacement such as properties of oil, the permeability and heterogeneity of the porous medium and physical and chemical characteristics of foam. In the present work, we have conducted a comprehensive series of experiments using customised Hele-Shaw cells filled with either water or oil to describe the effects of foam quality, permeability of the cell as well as the injection rate on the apparent viscosity of foam which is required to investigate foam displacement. Our results reveal the significant impact of foam texture and bubble size on the foam apparent viscosity. Foams with smaller bubble sizes have a higher apparent viscosity. This statement only applies (strictly speaking) when the foam quality is constant. However, wet foams with smaller bubbles may have lower apparent viscosity compared to dry foams with larger bubbles. Furthermore, our results show the occurrence of more stable foam-water fronts as foam quality decreases. Besides, the complexity of oil displacement by foam as well as its destabilizing effects on foam displacement has been discussed. Our results extend the physical understanding of foam-assisted liquid displacement in Hele-Shaw cell which is a step towards understanding the foam flow behaviour in more complex systems such as porous media.

  15. Blood Flow through an Open-Celled Foam

    NASA Astrophysics Data System (ADS)

    Ortega, Jason; Maitland, Duncan

    2011-11-01

    The Hazen-Dupuit-Darcy (HDD) equation is commonly used in engineering applications to model the pressure gradient of flow through a porous media. One major advantage of this equation is that it simplifies the complex geometric details of the porous media into two coefficients: the permeability, K, and form factor, C. However through this simplification, the flow details within the porous media are no longer accessible, making it difficult to study the phenomena that contribute to changes in K and C due to clotting of blood flow. To obtain a more detailed understanding of blood flow through a porous media, a direct assessment of the complex interstitial geometry and flow is required. In this study, we solve the Navier-Stokes equations for Newtonian and non-Newtonian blood flow through an open-celled foam geometry obtained from a micro-CT scan. The nominal strut size of the foam sample is of O(10e-5) m and the corresponding Reynolds number based upon this length ranges up to O(10). Fitting the pressure gradient vs. Darcy velocity data with the HDD equation demonstrates that both viscous and inertial forces play an important role in the flow through the foam at these Reynolds numbers. Recirculation zones are observed to form in the wake of the pore struts, producing regions of flow characterized by both low shear rates and long fluid residence times, factors of which have been shown in previous studies to promote blood clotting.

  16. pH-responsive aqueous foams stabilized by hairy latex particles.

    PubMed

    Fujii, Syuji; Mochizuki, Michiru; Aono, Kodai; Hamasaki, Sho; Murakami, Ryo; Nakamura, Yoshinobu

    2011-11-01

    Polystyrene (PS) latex particles carrying pH-responsive poly[2-(diethylamino)ethyl methacrylate] (PDEA) hair (PDEA-PS particles) were synthesized by dispersion polymerization and characterized in terms of diameter, diameter distribution, morphology, chemical composition, surface chemistry, and pH-response using scanning electron microscopy (SEM), elemental microanalysis, (1)H nuclear magnetic resonance spectroscopy, the laser diffraction method, and zeta potential measurements. The hairy particles can act as pH-responsive stabilizers of aqueous foams by adsorption at the air-water surface. Above pH 8.0, where particles have nonprotonated PDEA hair, which is relatively hydrophobic, particle-stabilized foams are stable for at least 1 month. Optical microscopy and SEM confirmed that flocculated PDEA-PS latex particles were adsorbed at the air-water interface and stabilized the aqueous foams. At pH 6.1 and 7.1, relatively stable foams can be prepared that remain stable for at least 24 h. SEM studies indicated that the PDEA-PS particles were adsorbed at the air-water interface as a monolayer at pH 6.1. At pH 5.1 and 3.1, where the particles have cationic water-soluble PDEA hairs with hydrophilic character, no foam was formed. Rapid defoamation can be induced by lowering the solution pH; the addition of acid caused the in situ protonation of 2-(diethylamino)ethyl methacrylate residues, which impart water-soluble hydrophilic character to the PDEA hair, and the PDEA-PS particles desorbed from the air-water interface. The foaming and defoaming cycles could be repeated at least five times.

  17. Use of aqueous foam to reduce radioactive material dispersal in sabotage incidents

    SciTech Connect

    Hartman, W.F.

    1986-01-01

    One potential type of sabotage incident in a nuclear facility involves the use of a large quantity of high explosive to disperse radioactive material into the atmosphere. This paper discusses the possible use of aqueous foam to reduce the consequences of such an event under the assumption that the location of the explosive is known and that some minimal time is available to emplace a mitigation system. Work conducted over the past several years has shown that low expansion ratio aqueous foams (e.g., 60 parts of air to one part water-soap concentrate solution by volume) exhibit exemplary properties in reducing the effects of a detonation. Not only does the foam significantly reduce the release of fine particulate which attempt to pass through it, but it also exhibits unusual pressure attentuation properties. Data demonstrating both the particle capture and pressure attenuation properties are presented along with information relative to generation of foam and some of the logistical constraints involved in its use.

  18. The use of aqueous foam to reduce radioactive material dispersal in sabotage incidents

    SciTech Connect

    Hartman, W.F.

    1986-01-01

    One potential type of sabotage incident in a nuclear facility involves the use of a large quantity of high explosive to disperse radioactive material into the atmosphere. This paper discusses the possible use of aqueous foam to reduce the consequences of such an event under the assumption that the location of the explosive is known and that some minimal time is available to emplace a mitigation system. Work conducted over the past several years has shown that low expansion ratio aqueous foams (e.g., 60 parts of air to one part water-soap concentrate solution by volume) exhibit exemplary properties in reducing the effects of a detonation. Not only does the foam significantly reduce the release of fine particulate which attempt to pass through it, but it also exhibits unusual pressure attenuation properties. Data demonstrating both the particle capture and pressure attenuation properties are presented along with information relative to generation of foam and some of the logistical constraints involved in its use.

  19. Oil/Water Emulsion and Aqueous Film Forming Foam (AFFF) Treatment Using Air-Sparged Hydrocyclone Technology

    DTIC Science & Technology

    2003-01-01

    Aqueous Film Forming Foam (AFFF) Treatment Using Air-Sparged Hydrocyclone Technology January 2003 Report Documentation Page Form ApprovedOMB No. 0704...2003 to 00-00-2003 4. TITLE AND SUBTITLE Oil/Water Emulsion and Aqueous Film Forming Foam (AFFF) Treatment Using Air-Sparged Hydrocyclone Technology...iii LIST OF FIGURES Page Figure 1. Air-Sparged Hydrocyclone (ASH) Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Figure 2. ASH

  20. Choked foam flows in a convergent-divergent nozzle

    SciTech Connect

    Beattie, D.R.H.

    1980-01-01

    This paper deals primarily with comparative evaluations of experimental data for choked foam flows in a convergent-divergent nozzle. Interpretations of data are examined with the assumption that the gas concentration profile is either a flat residage profile, or it is examined where the gas concentration profile is not flat. Both possibilities of a flat residage profile and a non-flat residage profile are considered.

  1. Ciliary Blood Flow and Aqueous Humor Production

    PubMed Central

    Kiel, J.W.; Hollingsworth, M.; Rao, R.; Chen, M.; Reitsamer, H.A.

    2010-01-01

    Aqueous humor production is a metabolically active process sustained by the delivery of oxygen and nutrients and removal of metabolic waste by the ciliary circulation. This article describes our investigations into the relationship between ciliary blood flow and aqueous humor production. The results presented indicate that there is a dynamic relationship between ciliary blood flow and aqueous humor production, with production being blood flow independent above a critical level of perfusion, and blood flow dependent below it. The results also show that the plateau portion of the relationship shifts up or down depending on the level of secretory stimulation or inhibition, and that oxygen is one critical factor provided by ciliary blood flow. Also presented is a theoretical model of ocular hydrodynamics incorporating these new findings. PMID:20801226

  2. pH- and temperature-responsive aqueous foams stabilized by hairy latex particles.

    PubMed

    Fujii, Syuji; Akiyama, Ko; Nakayama, Saori; Hamasaki, Sho; Yusa, Shin-ichi; Nakamura, Yoshinobu

    2015-01-21

    Polystyrene (PS) particles carrying pH- and temperature-responsive poly[2-(dimethylamino)ethyl methacrylate] (PDMA) hairs (PDMA-PS particles) were synthesized by dispersion polymerization. The diameter, diameter distribution, morphology, chemical composition and surface chemistry of the particles were characterized using scanning electron microscopy (SEM), elemental microanalysis, dynamic light scattering and zeta potential measurements. The hydrophilicity-hydrophobicity balance of the PDMA could be tuned by varying both pH and temperature and therefore these sterically stabilized particles acted as doubly stimuli-responsive stabilizers for aqueous foams by adsorption and desorption to/from the air-water interface. At and above pH 6.0, in which range the PDMA hairs were either non-protonated or partially protonated, particle-stabilized foams were formed at both 23 and 55 °C. The foam prepared at 55 °C was the more stable of the two, lasting for at least 24 h, whereas the 23 °C foam destabilized within 24 h. SEM studies indicated that the particles adsorbed at the air-water interface as monolayers at 23 °C and as multilayers at 55 °C. At and below pH 5, in which range the hairs were cationic, hydrophilic and water-soluble, no foam was formed irrespective of temperature. Rapid defoaming could be induced by lowering the solution pH at both temperatures, due to rapid in situ protonation of the PDMA hairs, prompting the PDMA-PS particles to desorb from the air-water interface. The foaming and defoaming cycles could be repeated at least five times.

  3. Responsive Aqueous Foams Stabilized by Silica Nanoparticles Hydrophobized in Situ with a Conventional Surfactant.

    PubMed

    Zhu, Yue; Pei, Xiaomei; Jiang, Jianzhong; Cui, Zhenggang; Binks, Bernard P

    2015-12-01

    In the recent past, switchable surfactants and switchable/stimulus-responsive surface-active particles have been of great interest. Both can be transformed between surface-active and surface-inactive states via several triggers, making them recoverable and reusable afterward. However, the synthesis of these materials is complicated. In this paper we report a facile protocol to obtain responsive surface-active nanoparticles and their use in preparing responsive particle-stabilized foams. Hydrophilic silica nanoparticles are initially hydrophobized in situ with a trace amount of a conventional cationic surfactant in water, rendering them surface-active such that they stabilize aqueous foams. The latter can then be destabilized by adding equal moles of an anionic surfactant, and restabilized by adding another trace amount of the cationic surfactant followed by shaking. The stabilization-destabilization of the foams can be cycled many times at room temperature. The trigger is the stronger electrostatic interaction between the oppositely charged surfactants than that between the cationic surfactant and the negatively charged particles. The added anionic surfactant tends to form ion pairs with the cationic surfactant, leading to desorption of the latter from particle surfaces and dehydrophobization of the particles. Upon addition of another trace amount of cationic surfactant, the particles are rehydrophobized in situ and can then stabilize foams again. This principle makes it possible to obtain responsive surface-active particles using commercially available inorganic nanoparticles and conventional surfactants.

  4. Lead and copper removal from aqueous solutions using carbon foam derived from phenol resin.

    PubMed

    Lee, Chang-Gu; Jeon, Jun-Woo; Hwang, Min-Jin; Ahn, Kyu-Hong; Park, Chanhyuk; Choi, Jae-Woo; Lee, Sang-Hyup

    2015-07-01

    Phenolic resin-based carbon foam was prepared as an adsorbent for removing heavy metals from aqueous solutions. The surface of the produced carbon foam had a well-developed open cell structure and the specific surface area according to the BET model was 458.59m(2)g(-1). Batch experiments showed that removal ratio increased in the order of copper (19.83%), zinc (34.35%), cadmium (59.82%), and lead (73.99%) in mixed solutions with the same initial concentration (50mgL(-1)). The results indicated that the Sips isotherm model was the most suitable for describing the experimental data of lead and copper. The maximum adsorption capacity of lead and copper determined to Sips model were 491mgg(-1) and 247mgg(-1). The obtained pore diffusion coefficients for lead and copper were found to be 1.02×10(-6) and 2.42×10(-7)m(2)s(-1), respectively. Post-sorption characteristics indicated that surface precipitation was the primary mechanism of lead and copper removal by the carbon foam, while the functional groups on the surface of the foam did not affect metal adsorption.

  5. Use of microorganisms immobilized on composite polyurethane foam to remove Cu(II) from aqueous solution.

    PubMed

    Zhou, Lin-Cheng; Li, Yan-Feng; Bai, Xue; Zhao, Guang-Hui

    2009-08-15

    Composite polyurethane (PU) foams were made via the polymerization of toluene diisocyanate (TDI) and polyether polyol with activated carbon fiber, and immobilized microorganisms on polyurethane (IPU) foam were prepared by cultivating the microbe B350 in a mixture of culture medium and PU. We used batch adsorption techniques to study the removal of Cu(II) ions from aqueous solutions via PU and IPU. Moreover, the effects of pH, temperature, carrier amount, and biosorption time on the removal rate of Cu(II), adsorption equilibrium, and adsorption kinetics were investigated in detail. The IPU showed an excellent removal rate for Cu(II). The adsorption kinetics data were in good agreement with the pseudo-second-order rate model, and the adsorption isotherms could be adequately described by the Langmuir equation. For synthetic wastewater containing Cu(II), the removal rates for Cu(II) and COD after 4h treatment were 85% and 80%, respectively.

  6. Aqueous outflow: Segmental and distal flow

    PubMed Central

    Swaminathan, Swarup S.; Oh, Dong-Jin; Kang, Min Hyung; Rhee, Douglas J.

    2014-01-01

    A prominent risk factor of primary open-angle glaucoma is ocular hypertension, a pathologic state caused by impaired outflow of aqueous humor through the trabecular meshwork within the iridocorneal angle. The juxtacanalicular region of the trabecular meshwork and the inner wall of Schlemm canal have been identified as the main contributors to aqueous outflow resistance, and both extracellular matrix within the trabecular meshwork and trabecular meshwork cell shape have been shown to affect outflow. Overexpression of multiple ECM proteins in perfused cadaveric human eyes has led to increased outflow resistance and elevated IOP. Pharmacologic agents targeting trabecular meshwork cytoskeletal arrangements have been developed after multiple studies demonstrated the importance of cell shape on outflow. Several groups have shown that aqueous outflow occurs only at certain segments of the trabecular meshwork circumferentially, a concept known as segmental flow. This is based on the theory that aqueous outflow is dependent on the presence of discrete pores within the Schlemm canal. Segmental flow has been described in the eyes of multiple species, including primate, bovine, mouse, and human samples. While the trabecular meshwork appears to be the major source of resistance, trabecular meshwork bypass procedures have been unable to achieve the degree of IOP reduction observed with trabeculectomy, reflecting the potential impact of distal flow, or flow through Schlemm canal and collector channels, on outflow. Multiple studies have demonstrated that outflow occurs preferentially near collector channels, suggesting that these distal structures may be more important to aqueous outflow than previously believed. PMID:25088623

  7. Convective heat transfer in foams under laminar flow in pipes and tube bundles

    PubMed Central

    Attia, Joseph A.; McKinley, Ian M.; Moreno-Magana, David; Pilon, Laurent

    2014-01-01

    The present study reports experimental data and scaling analysis for forced convection of foams and microfoams in laminar flow in circular and rectangular tubes as well as in tube bundles. Foams and microfoams are pseudoplastic (shear thinning) two-phase fluids consisting of tightly packed bubbles with diameters ranging from tens of microns to a few millimeters. They have found applications in separation processes, soil remediation, oil recovery, water treatment, food processes, as well as in fire fighting and in heat exchangers. First, aqueous solutions of surfactant Tween 20 with different concentrations were used to generate microfoams with various porosity, bubble size distribution, and rheological behavior. These different microfoams were flowed in uniformly heated circular tubes of different diameter instrumented with thermocouples. A wide range of heat fluxes and flow rates were explored. Experimental data were compared with analytical and semi-empirical expressions derived and validated for single-phase power-law fluids. These correlations were extended to two-phase foams by defining the Reynolds number based on the effective viscosity and density of microfoams. However, the local Nusselt and Prandtl numbers were defined based on the specific heat and thermal conductivity of water. Indeed, the heated wall was continuously in contact with a film of water controlling convective heat transfer to the microfoams. Overall, good agreement between experimental results and model predictions was obtained for all experimental conditions considered. Finally, the same approach was shown to be also valid for experimental data reported in the literature for laminar forced convection of microfoams in rectangular minichannels and of macrofoams across aligned and staggered tube bundles with constant wall heat flux. PMID:25552745

  8. Convective heat transfer in foams under laminar flow in pipes and tube bundles.

    PubMed

    Attia, Joseph A; McKinley, Ian M; Moreno-Magana, David; Pilon, Laurent

    2012-12-01

    The present study reports experimental data and scaling analysis for forced convection of foams and microfoams in laminar flow in circular and rectangular tubes as well as in tube bundles. Foams and microfoams are pseudoplastic (shear thinning) two-phase fluids consisting of tightly packed bubbles with diameters ranging from tens of microns to a few millimeters. They have found applications in separation processes, soil remediation, oil recovery, water treatment, food processes, as well as in fire fighting and in heat exchangers. First, aqueous solutions of surfactant Tween 20 with different concentrations were used to generate microfoams with various porosity, bubble size distribution, and rheological behavior. These different microfoams were flowed in uniformly heated circular tubes of different diameter instrumented with thermocouples. A wide range of heat fluxes and flow rates were explored. Experimental data were compared with analytical and semi-empirical expressions derived and validated for single-phase power-law fluids. These correlations were extended to two-phase foams by defining the Reynolds number based on the effective viscosity and density of microfoams. However, the local Nusselt and Prandtl numbers were defined based on the specific heat and thermal conductivity of water. Indeed, the heated wall was continuously in contact with a film of water controlling convective heat transfer to the microfoams. Overall, good agreement between experimental results and model predictions was obtained for all experimental conditions considered. Finally, the same approach was shown to be also valid for experimental data reported in the literature for laminar forced convection of microfoams in rectangular minichannels and of macrofoams across aligned and staggered tube bundles with constant wall heat flux.

  9. Synchronized diffusive-wave spectroscopy: Principle and application to sound propagation in aqueous foams.

    PubMed

    Crassous, Jérôme; Chasle, Patrick; Pierre, Juliette; Saint-Jalmes, Arnaud; Dollet, Benjamin

    2016-03-01

    We present an experimental method to measure oscillatory strains in turbid material. The material is illuminated with a laser, and the speckle patterns are recorded. The analysis of the deformations of the optical path length shows that the speckle patterns are modulated at the strain frequency. By recording those patterns synchronously with the strain source, we are able to measure the amplitude and the phase of the strain. This method is tested in the specific case of an aqueous foam where an acoustic wave propagates. The effects of material internal dynamics and heterogeneous deformations are also discussed.

  10. Lightweight and strong cellulose materials made from aqueous foams stabilized by nanofibrillated cellulose.

    PubMed

    Cervin, Nicholas T; Andersson, Linnéa; Ng, Jovice Boon Sing; Olin, Pontus; Bergström, Lennart; Wågberg, Lars

    2013-02-11

    A lightweight and strong porous cellulose material has been prepared by drying aqueous foams stabilized with surface-modified nanofibrillated cellulose (NFC). This material differs from other dry, particle stabilized foams in that renewable cellulose is used as stabilizing particles. Confocal microscopy and high speed video imaging show that the octylamine-coated, rod-shaped NFC nanoparticles residing at the air-liquid interface prevent the air bubbles from collapsing or coalescing. Stable wet foams can be achieved at solids content around 1% by weight. Careful removal of the water results in a cellulose-based material with a porosity of 98% and a density of 30 mg cm(-3). These porous cellulose materials have a higher Young's modulus than porous cellulose materials made from freeze-drying, at comparable densities, and have a compressive energy absorption of 56 kJ m(-3) at 80% strain. Measurement with the aid of an autoporosimeter revealed that most pores are in the range of 300 to 500 μm.

  11. Bioconcentration of aqueous film-forming foam (AFFF) in juvenile rainbow trout (Oncorhyncus mykiss).

    PubMed

    Yeung, Leo W Y; Mabury, Scott A

    2013-01-01

    This work investigated the bioconcentration of PFASs in juvenile rainbow trout by exposing the fish in separate tanks under flow-through conditions to water continuously spiked with either of the AFFFs FC-203CF light water AFFF 3% (3M) or Niagara 1-3 (Angus Fire); a nonspiked tank served as the control. Three fish in each tank were collected after 1, 3, 6, and 11 days of exposure, and 3, 7, 14, and 25 days of depuration. Liver and carcass homogenate samples were analyzed for 20 PFASs using LC-MS/MS. PFDS, PFOS, PFHxS, and EtFOSAA were detected in fish exposed to the 3M foam, while 6:2 and 8:2 FTSASs, 6:2 and 8:2 FTSAs, 5:3 and 7:3 FTCAs were measured in fish exposed to Angus Fire foam. Bioconcentration factors and rate constants for uptake and depuration were calculated. Total and extractable organofluorine were measured in the fish samples. After fish were exposed to AFFFs, not only known PFASs but also other unknown organofluorines were bioconcentrated. Compared to the control group, significantly greater amounts (at least 10-fold) and proportion of unidentified PFASs were found in both liver and carcass homogenate ranging from ∼50% in 3M foam up to 95% in the Angus Fire foam at the end of exposure.

  12. Viscoelasticity of liquid organic foam: Relaxations, temporal dependence, and bubble loading effects on flow behavior

    NASA Astrophysics Data System (ADS)

    Kropka, Jamie M.; Celina, Mathew

    2010-07-01

    Liquid organic foams are prepared using a new blowing process based on the chemical generation of carbon dioxide. The foams are volumetrically stable for periods up to hours and can be fabricated with gas volume fractions ranging from 0.10 to 0.95. Both the "fresh" and temporal dependences of the linear viscoelastic response of these materials are evaluated. The organic foams exhibit rheological behavior characteristic of their aqueous counterparts: a weak dependence of the shear moduli over an extended frequency/time regime that is bounded by both a fast and slow relaxation. The onset of the fast mechanical response of the organic foams occurs at approximately the same frequency as in aqueous foams despite the continuous phase viscosity differing by orders of magnitude between the systems. This suggests that the viscosity does not affect the time scale of the "anomalous" viscous loss characteristic of these materials, which challenges currently proposed mechanisms for this dissipation and leaves the origin of the loss behavior unclear. The relative contribution of cell growth and bubble motion to the slow relaxation is also discerned by evaluating the relation between the transient and dynamic responses of the foam. Finally, the development of elasticity in the foam due to bubble interactions is analyzed and a bubble slip process is postulated to account for the lack of a true elastic response of the foam at intermediate time scales (between the fast and slow mechanical response) when gas fractions exceed 0.64.

  13. Surface properties and flow behavior of foams in relation to fluid displacement in porous media

    SciTech Connect

    Ling, T.F.T.

    1987-01-01

    Surface properties such as surface tension, surface viscosity, foaminess, foam quality, apparent foam viscosity, rate of drainage, bubble size distribution, etc., were investigated and correlated with fluid displacement in porous media. The effect of chain length compatability, i.e., similarity, on surface properties of foaming solutions and fluid displacement in porous media were also studied. Two mathematical models for foam flow through porous media were developed which can be used to predict foam viscosity and foam behavior in porous media. To better understand the foam stability, a numerical solution of the Poisson-Boltzmann equation in two dimensional bispherical coordinates was obtained and used to calculate the potential energy of interaction between two spherical bubbles. Predicted potential energies were consistent with results from other models. The effect of polymer on foam properties was also studied. The improvement of surface activity of the surfactants was due mainly to the effect of the excluded polymer volume and electrical double layers. The change of the surface properties of the polymer containing foam was dependent on the counterbalance of the rheology of the liquid films and the water content in the liquid films. These studies have been successfully applied to enhanced oil recovery and to characterization of biological polymers. A concept of surfactant-polymer-foam flooding is proposed, including the use of nonionic surfactants to form alcohol-free microemulsions and the injection of foam for the mobility control in heavy oil recovery.

  14. Effect of pH and interaction between egg white protein and hydroxypropymethylcellulose in bulk aqueous medium on foaming properties.

    PubMed

    Sadahira, Mitie S; Lopes, Fernanda C Rezende; Rodrigues, Maria I; Yamada, Aureo T; Cunha, Rosiane L; Netto, Flavia M

    2015-07-10

    Egg white protein (EW) is used as surface-active ingredient in aerated food and hydroxypropylmethylcellulose (HPMC) is a polysaccharide that behaves as a surfactant. This study aimed at investigating the effects of process parameters biopolymer concentration (2.0-5.0%, w/w), EW:HPMC ratio (2:1-18:1), pH (3.0-6.0), and the influence of biopolymers' behavior in aqueous solution at different pH on the foaming properties (overrun, drainage, and bubble growth rate). Process parameters had effect on foaming properties. The pH was the major factor influencing the type of EW/HPMC interaction and affected the foaming properties of biopolymer mixture. At pH 3.0, EW and HPMC showed thermodynamic compatibility leading to better foaming properties, higher foaming capacity, and stability than without HPMC addition whereas at pH 4.5 and 6.0, EW and HPMC are incompatible that causes lower stability concerning the disproportionation comparing to foam without HPMC. At pH between 3.0 and 4.5, HPMC improves foaming properties of aerated products.

  15. Study of Displacement Efficiency and Flow Behavior of Foamed Gel in Non-Homogeneous Porous Media

    PubMed Central

    Bai, Baojun; Wei, Mingzhen

    2015-01-01

    Field trials have demonstrated that foamed gel is a very cost-effective technology for profile modification and water shut-off. However, the mechanisms of profile modification and flow behavior of foamed gel in non-homogeneous porous media are not yet well understood. In order to investigate these mechanisms and the interactions between foamed gel and oil in porous media, coreflooding and pore-scale visualization waterflooding experiments were performed in the laboratory. The results of the coreflooding experiment in non-homogeneous porous media showed that the displacement efficiency improved by approximately 30% after injecting a 0.3 pore volume of foamed gel, and was proportional to the pore volumes of the injected foamed gel. Additionally, the mid-high permeability zone can be selectively plugged by foamed gel, and then oil located in the low permeability zone will be displaced. The visualization images demonstrated that the amoeba effect and Jamin effect are the main mechanisms for enhancing oil recovery by foamed gel. Compared with conventional gel, a unique benefit of foamed gel is that it can pass through micropores by transforming into arbitrary shapes without rupturing, this phenomenon has been named the amoeba effect. Additionally, the stability of foam in the presence of crude oil also was investigated. Image and statistical analysis showed that these foams boast excellent oil resistance and elasticity, which allows them to work deep within formations. PMID:26030282

  16. Pressure-driven and free-rise foam flow.

    SciTech Connect

    Bourdon, Christopher Jay; Moffat, Harry K.; Grillet, Anne Mary; Noble, David R.; Kropka, Jamie Michael; Rao, Rekha Ranjana; Kraynik, Andrew Michael; Leming, Sarah Kathryn; Brotherton, Christopher M.; Celina, Mathias C.; Mondy, Lisa Ann

    2008-08-01

    Many weapons components (e.g. firing sets) are encapsulated with blown foams. Foam is a strong lightweight material--good compromise between conflicting needs of structural stability and electronic function. Current foaming processes can lead to unacceptable voids, property variations, cracking, and slipped schedules which is a long-standing issue. Predicting the process is not currently possible because the material is polymerizing and multiphase with changing microstructure. The goals of this project is: (1) Produce uniform encapsulant consistently and improve processability; (2) Eliminate metering issues/voids; (3) Lower residual stresses, exotherm to protect electronics; and (4) Maintain desired properties--lightweight, strong, no delamination/cracking, and ease of removal. The summary of achievements in the first year are: (1) Developed patentable chemical foaming chemistry - TA; (2) Developed persistent non-curing foam for systematic evaluation of fundamental physics of foams--Initial testing of non-curing foam shows that surfactants very important; (3) Identified foam stability strategy using a stacked reaction scheme; (4) Developed foam rheology methodologies and shear apparatuses--Began testing candidates for shear stability; (5) Began development of computational model; and (6) Development of methodology and collection of property measurements/boundary conditions for input to computational model.

  17. Stochastic field modeling of cavitating flows in OpenFOAM

    NASA Astrophysics Data System (ADS)

    Ranft, Michael; Class, Andreas G.

    2013-11-01

    In analysis is presented for a fluidic diode with low/high pressure drop in forward/reverse flow direction. Accurate description of cavitation is needed due to the dominant effect of vapor bubbles on sound speed. The stochastic field method developed in represents the statistics of growing cavitation bubbles by a set of stochastic fields of vapor fraction which evolve according to the Rayleigh-Plesset equation and local instantaneous LES flow conditions. Cavitation may originate from nucleation sites in the core of turbulent vortices. In this work a RANS model is used instead of LES. Local turbulent pressure fluctuations are recovered based on kinetic energy k of turbulence and its Dissipation ɛ. In the Rayleigh-Plesset equation these fluctuations are represented by a Wiener process which is superimposed on the mean pressure. Usually a set of stochastic fields is introduced for each stochastic variable. Here two independent Wiener processes, both acting on the vapor-fraction stochastic fields, drive the evolution of vapor bubble growth, so that a single set of stochastic fields can be maintained. The proposed methodology is implemented in OpenFOAM and applied to verification cases including the fluidic diode. Funded by ANPS.

  18. Experimental results for oscillatory water flow in 10-ppi metal foam at low-frequencies

    NASA Astrophysics Data System (ADS)

    Bağcı, Ö.; Arbak, A.; De Paepe, M.; Dukhan, N.

    2016-09-01

    This experimental study presents results and interpretation of oscillatory water flow in open-cell metal foam. The tested foam had 10 pores per inch and a porosity of 88%. At relatively low frequencies, three flow displacements were employed in the experiment. The influence of frequency and displacement on pressure loss and friction factor is discussed. A correlation of friction factor as a function of the kinetic Reynolds number was determined. Porous media parameters, permeability and drag coefficient, were also found for the same foam via steady-state flow experiments in the Darcy and Forchheimer regimes. The friction factor of oscillating flow was found to be higher than that of steady state. The findings of this study are considered important for oscillating heat transfer in metal foam.

  19. Investigation of foam flow in a 3D printed porous medium in the presence of oil.

    PubMed

    Osei-Bonsu, Kofi; Grassia, Paul; Shokri, Nima

    2017-03-15

    Foams demonstrate great potential for displacing fluids in porous media which is applicable to a variety of subsurface operations such as the enhanced oil recovery and soil remediation. The application of foam in these processes is due to its unique ability to reduce gas mobility by increasing its effective viscosity and to divert gas to un-swept low permeability zones in porous media. The presence of oil in porous media is detrimental to the stability of foams which can influence its success as a displacing fluid. In the present work, we have conducted a systematic series of experiments using a well-characterised porous medium manufactured by 3D printing technique to evaluate the influence of oil on the dynamics of foam displacement under different boundary conditions. The effects of the type of oil, foam quality and foam flow rate were investigated. Our results reveal that generation of stable foam is delayed in the presence of light oil in the porous medium compared to heavy oil. Additionally, it was observed that the dynamics of oil entrapment was dictated by the stability of foam in the presence of oil. Furthermore, foams with high gas fraction appeared to be less stable in the presence of oil lowering its recovery efficiency. Pore-scale inspection of foam-oil dynamics during displacement revealed formation of a less stable front as the foam quality increased, leading to less oil recovery. This study extends the physical understanding of oil displacement by foam in porous media and provides new physical insights regarding the parameters influencing this process. Copyright © 2016. Published by Elsevier Inc.

  20. Determination of the specific area of liquid gas and the velocity of weak pressure waves in aqueous foams

    NASA Technical Reports Server (NTRS)

    Saint-Cloud, Jean; Guerraud, Claude; Moreau, Michel; Manson, Numa

    1988-01-01

    The specific area of an aqueous foam contained in a tube is obtained by determining the fraction of the quantity of light emitted by a source and diffused by the specific area of the column of the foam. The velocity of the waves of weak pressure (which propagate in the air with the velocity of sound) is measured by noticing the moment when the wave penetrates the column and the moment when, having reached the opposite side, it determines a variation of the light diffused by the area of the latter.

  1. Sonochemical degradation of perfluorinated chemicals in aqueous film-forming foams.

    PubMed

    Rodriguez-Freire, Lucia; Abad-Fernández, Nerea; Sierra-Alvarez, Reyes; Hoppe-Jones, Christiane; Peng, Hui; Giesy, John P; Snyder, Shane; Keswani, Manish

    2016-11-05

    Aqueous film-forming foams (AFFFs) are complex mixtures containing 1-5% w/w fluorocarbons (FCs). Here, we have investigated degradation of two commercial AFFF formulations, 3M and Ansul, using sound field at 500kHz and 1MHz, with varying initial concentrations ranging from 200 to 930× dilution. The foams were readily degraded by 1MHz, with percentage of defluorination ranging from 11.1±1.4% (200× dilution of 3M) to 47.1±5.8% (500× dilution of Ansul). Removal of total organic carbon (TOC) ranged from 16.0±1.4% (200× dilution Ansul) to 39.0±7.2% (500× dilution Ansul). Degradation of AFFF was affected by sound frequency with rates of defluorination 10-fold greater when the frequency was 1MHz than when it was 500kHz. Mineralization of TOC was 1.5- to 3.0-fold greater under 1MHz than 500kHz. Rate of fluoride release was 60% greater for the greatest initial concentration of FC in Ansul compared to the least initial concentration. While the rate of mineralization of AFFF was directly proportional to the initial concentration of Ansul, that was not the case for 3M, where the rates of mineralization were approximately the same for all three initial concentrations. Results of the study demonstrate that sonolysis is a promising technology to effectively treat AFFFs. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. On the implicit density based OpenFOAM solver for turbulent compressible flows

    NASA Astrophysics Data System (ADS)

    Fürst, Jiří

    The contribution deals with the development of coupled implicit density based solver for compressible flows in the framework of open source package OpenFOAM. However the standard distribution of OpenFOAM contains several ready-made segregated solvers for compressible flows, the performance of those solvers is rather week in the case of transonic flows. Therefore we extend the work of Shen [15] and we develop an implicit semi-coupled solver. The main flow field variables are updated using lower-upper symmetric Gauss-Seidel method (LU-SGS) whereas the turbulence model variables are updated using implicit Euler method.

  3. The Soil Foam Drainage Equation - an alternative model for unsaturated flow in porous media

    NASA Astrophysics Data System (ADS)

    Assouline, Shmuel; Lehmann, Peter; Hoogland, Frouke; Or, Dani

    2017-04-01

    The analogy between the geometry and dynamics of wet foam drainage and gravity drainage of unsaturated porous media expands modeling capabilities for capillary flows and supplements the standard Richards equation representation. The governing equation for draining foam (or a soil variant termed the soil foam drainage equation - SFDE) obviates the need for macroscopic unsaturated hydraulic conductivity function by an explicit account of diminishing flow pathway sizes as the medium gradually drains. Potential advantages of the proposed drainage foam formalism include direct description of transient flow without requiring constitutive functions; evolution of capillary cross sections that provides consistent description of self-regulating internal fluxes (e.g., towards field capacity); and a more intuitive geometrical picture of capillary flow across textural boundaries. We will present new and simple analytical expressions for drainage rates and volumes from unsaturated porous media subjected to different boundary conditions that are in good agreement with the numerical solution of the SFDE and experimental results. The foam drainage methodology expands the range of tools available for describing and quantifying unsaturated flows and provides geometrically tractable links between evolution of liquid configuration and flow dynamics in unsaturated porous media. The resulting geometrical representation of capillary drainage could improve understanding of colloid and pathogen transport. The explicit geometrical interpretation of flow pathways underlying the hydraulic functions used by the Richards equation offers new insights that benefit both approaches.

  4. MECHANISTIC STUDIES OF IMPROVED FOAM EOR PROCESSES

    SciTech Connect

    William R. Rossen

    2004-06-14

    The objective of this research is to widen the application of foam to enhanced oil recovery (EOR) by investigating fundamental mechanisms of foams in porous media. This research will lay the groundwork for more applied research on foams for improved sweep efficiency in miscible gas, steam and surfactant-based EOR. Task 1 investigates the pore-scale interactions between foam bubbles and polymer molecules. Task 2 examines the mechanisms of gas trapping, and interaction between gas trapping and foam effectiveness. Task 3 investigates mechanisms of foam generation in porous media. Significant progress was made during this period on all three Tasks. Regarding Task 1, we continued comparisons of foam behavior in sandpacks with and without polymer and oil. As in our previous results, decane was moderately destabilizing to foam. Xanthan polymer did not stabilize foam in the presence of decane in this case. Rather, it appears to have destabilized foam, so that pressure gradient decreased in spite of the increase in aqueous-phase viscosity. Research on Task 2 included the first shake-down experiments with our new apparatus for gas-phase tracer tests for direct measurement of trapped-gas saturation with foam. In addition, we began to analyze CT images of gas-phase tracer in foam displacements, which offers an independent measure of trapped-gas fraction and insights into the roles of convection of tracer in flowing gas and diffusion into trapped gas. Research on Task 3 included foam generation experiments in heterogeneous sandpacks and beadpacks and modeling of discontinuous changes in state such as foam generation. The experiments found the same three regimes (coarse foam, strong foam, and intermediate regime) in heterogeneous sandpacks previously identified in homogeneous porous media. One implication is that there may be a minimum flow rate required for foam generation in even heterogeneous porous media. The dynamics in SAG foam processes in heterogeneous media are complex

  5. Dynamics of foam flow in porous media in the presence of oil

    NASA Astrophysics Data System (ADS)

    Shokri, N.; Osei-Bonsu, K.

    2016-12-01

    Foams demonstrate great potential for fluid displacement in porous media which is important in a number of subsurface operations such as the enhanced oil recovery and soil remediation. The application of foam in these processes is down to its unique ability to reduce gas mobility by increasing its effective viscosity and to divert gas to un-swept low permeability zones in porous media [1-4]. To investigate the fundamental aspects of foam flow in porous media, we have conducted a systematic series of experiment using a well-characterised porous medium manufactured by a high resolution 3D printer. This enabled us to design and control the properties of porous media with high accuracy. The model porous medium was initially saturated with oil. Then the pre-generated foam was injected into the model at well-defined injection rates to displace oil. The dynamics of foam-oil displacement in porous media was recorded using a digital camera controlled by a computer [5]. The recorded images were analysed in MATLAB to determine the dynamics of foam-oil displacement under different boundary conditions. Effects of the type of oil, foam quality and foam flow rate were investigated. Our results reveal that generation of stable foam is delayed in the presence of light oil in the porous medium compared to the heavy oil. Furthermore, higher foam quality appears to be less stable in the presence of oil lowering its recovery efficiency. Pore-scale inspection of foam-oil patterns formed during displacement revealed formation of a more stable front in the case of lower foam quality which affected the oil recovery efficiency. This study extends the physical understanding of governing mechanisms controlling oil displacement by foam in porous media. Grassia, P., E. Mas-Hernandez, N. Shokri, S.J. Cox, G. Mishuris, W.R. Rossen (2014), J. Fluid Mech., 751, 346-405. Grassia, P., C. Torres-Ulloa, S. Berres, E. Mas-Hernandez, N. Shokri (2016), European Physical Journal E, 39 (4), 42. Mas

  6. Foaming volume and foam stability

    NASA Technical Reports Server (NTRS)

    Ross, Sydney

    1947-01-01

    A method of measuring foaming volume is described and investigated to establish the critical factors in its operation. Data on foaming volumes and foam stabilities are given for a series of hydrocarbons and for a range of concentrations of aqueous ethylene-glycol solutions. It is shown that the amount of foam formed depends on the machinery of its production as well as on properties of the liquid, whereas the stability of the foam produced, within specified mechanical limitations, is primarily a function of the liquid.

  7. Identification of Novel Fluorochemicals in Aqueous Film-Forming Foams (AFFF) Used by the US Military

    PubMed Central

    Place, Benjamin J.; Field, Jennifer A.

    2012-01-01

    Aqueous film-forming foams (AFFFs) are a vital tool to fight large hydrocarbon fires and can be used by public, commercial, and military firefighting organizations. In order to possess these superior firefighting capabilities, AFFFs contain fluorochemical surfactants, of which many of the chemical identities are listed as proprietary. Large-scale controlled (e.g. training activities) and uncontrolled releases of AFFF have resulted in contamination of groundwater. Information on the composition of AFFF formulations is needed to fully define the extent of groundwater contamination and the first step is to fully define the fluorochemical composition of AFFFs used by the US military. Fast atom bombardment mass spectrometry (FAB-MS) and high resolution quadrupole-time-of-flight mass spectrometry (QTOF-MS) were combined to elucidate chemical formulas for the fluorochemicals in AFFF mixtures and, along with patent-based information, structures were assigned. Sample collection and analysis was focused on AFFFs that have been designated as certified for US military use. Ten different fluorochemical classes were identified in the seven military-certified AFFF formulations, and include anionic, cationic, and zwitterionic surfactants with perfluoroalkyl chain lengths ranging from 4-12. The environmental implications are discussed and research needs are identified. PMID:22681548

  8. Identification of novel fluorochemicals in aqueous film-forming foams used by the US military.

    PubMed

    Place, Benjamin J; Field, Jennifer A

    2012-07-03

    Aqueous film-forming foams (AFFFs) are a vital tool to fight large hydrocarbon fires and can be used by public, commercial, and military firefighting organizations. In order to possess these superior firefighting capabilities, AFFFs contain fluorochemical surfactants, of which many of the chemical identities are listed as proprietary. Large-scale controlled (e.g., training activities) and uncontrolled releases of AFFF have resulted in contamination of groundwater. Information on the composition of AFFF formulations is needed to fully define the extent of groundwater contamination, and the first step is to fully define the fluorochemical composition of AFFFs used by the US military. Fast atom bombardment mass spectrometry (FAB-MS) and high resolution quadrupole-time-of-flight mass spectrometry (QTOF-MS) were combined to elucidate chemical formulas for the fluorochemicals in AFFF mixtures, and, along with patent-based information, structures were assigned. Sample collection and analysis was focused on AFFFs that have been designated as certified for US military use. Ten different fluorochemical classes were identified in the seven military-certified AFFF formulations and include anionic, cationic, and zwitterionic surfactants with perfluoroalkyl chain lengths ranging from 4 to 12. The environmental implications are discussed, and research needs are identified.

  9. The Effect of Precursor Plasma Flow on Foam Targets in Wire Array Z-Pinch Experiments

    NASA Astrophysics Data System (ADS)

    Palmer, James B. A.; Lebedev, Sergey V.; Bland, Simon N.; Chittenden, Jeremy P.; Ampleford, David J.

    2002-12-01

    Previous experiments have demonstrated that the slow ablation rate of material from wire arrays results in the formation of a precursor plasma stream bombarding the axis [1]. This could have major repercussions for the centrally located foam targets used in dynamic and static walled hohlraum configurations on the Z facility at Sandia National Laboratory (SNL) [2]. Experiments to characterise the effect of precursor plasma flow on foam targets were carried out on the MAGPIE generator at Imperial College. The TPX foam used is similar in size and density to foam used in the experiments at SNL. Diagnostics included: x-pinch backlighter; x-ray framing cameras; diamond PCDs; laser shadowgraphy and interferometry; optical streak photography. Backlighter results suggested that the foam was compressed at a rate consistent with experimental estimates of the momentum of the bombarding plasma streams. Laser probing images, however, showed expansion of low density plasma from the foam surface that exhibited structure similar to an m=0 instability. Side-on XUV and x-ray imaging showed axially modulated emission from the foam.

  10. Determination of aromatic amines in aqueous extracts of polyurethane foam using hydrophilic interaction liquid chromatography and mass spectrometry.

    PubMed

    Johnson, Jakob Riddar; Karlsson, Daniel; Dalene, Marianne; Skarping, Gunnar

    2010-09-23

    A method is presented for the determination of aromatic amines in aqueous extracts of polyurethane (PUR) foam. The method is based on the extraction of PUR foam using aqueous acetic acid (0.1%, w/v) followed by determination of extracted aromatic amines using hydrophilic interaction liquid chromatography (HILIC) and tandem mass spectrometry (MS/MS) with positive electrospray ionisation. The injections of volumes up to 5 μL of aqueous solutions were made possible by on-column focusing with partially filled loop injections. The fragmentation patterns for 2,4- and 2,6-toluene diamine (TDA) and 4,4'-methylene dianiline (MDA) were clarified by performing a hydrogen-deuterium exchange study. TDA and MDA were determined using trideuterated 2,4- and 2,6-TDA and dideuterated 4,4'-MDA as internal standards. Linear calibration graphs were obtained over the range 0.025-0.5 μg mL(-1) with correlation coefficients >0.996 and the instrumental detection limit for each compound was <50 fmol. The stability of the amines was influenced by the matrix, so their concentrations decreased over time. Agreement was observed between the results of analyses of PUR foam extracts by HILIC-MS/MS and results obtained by ethyl chloroformate derivatisation and reversed phase (RP) liquid chromatography-mass spectrometry (LC-MS/MS). TDA was observed to be unstable in extracts of foam but not in pure solutions. Copyright © 2010 Elsevier B.V. All rights reserved.

  11. Simple shearing flow of dry soap foams with tetrahedrally close-packed structure

    SciTech Connect

    Reinelt, Douglas A.; Kraynik, Andrew M.

    2000-05-01

    The microrheology of dry soap foams subjected to quasistatic, simple shearing flow is analyzed. Two different monodisperse foams with tetrahedrally close-packed (TCP) structure are examined: Weaire-Phelan (A15) and Friauf-Laves (C15). The elastic-plastic response is evaluated by using the Surface Evolver to calculate foam structures that minimize total surface area at each value of strain. The foam geometry and macroscopic stress are piecewise continuous functions of strain. The stress scales as T/V{sup 1/3}, where T is surface tension and V is cell volume. Each discontinuity corresponds to large changes in foam geometry and topology that restore equilibrium to unstable configurations that violate Plateau's laws. The instabilities occur when the length of an edge on a polyhedral foam cell vanishes. The length can tend to zero smoothly or abruptly with strain. The abrupt case occurs when a small increase in strain changes the energy profile in the neighborhood of a foam structure from a local minimum to a saddle point, which can lead to symmetry-breaking bifurcations. In general, the new structure associated with each stable solution branch results from an avalanche of local topology changes called T1 transitions. Each T1 cascade produces different cell neighbors, reduces surface energy, and provides an irreversible, film-level mechanism for plastic yield behavior. Stress-strain curves and average stresses are evaluated by examining foam orientations that admit strain-periodic behavior. For some orientations, the deformation cycle includes Kelvin cells instead of the original TCP structure; but the foam does not remain perfectly ordered. Bifurcations during subsequent T1 cascades lead to disorder and can even cause strain localization. (c) 2000 Society of Rheology.

  12. Bubble fragmentation in a 2D foam flowing through a porous medium

    NASA Astrophysics Data System (ADS)

    Meheust, Y.; Géraud, B.; Cantat, I.; Dollet, B.

    2016-12-01

    Foams have been used for decades as displacing fluids for EOR and aquifer remediation, and more recently as carriers of chemical amendments for the remediation of the vadose zone. Apart from various interesting physico-chemical and biochemical properties, foams are better injection fluids due to their low sensitivity to gravity and their peculiar rheology: for foams with bubbles on the order of at least the typical pore size, viscous dissipation arises mostly from the contact zones between the soap films and the walls. In most experimental studies no local information of the foam structure can be obtained, and only global quantities such as the effective viscosity can be measured. In a recent study [1] we investigated foam flows through a two-dimensional porous medium consisting of circular obstacles positioned randomly in a horizontal transparent Hele-Shaw cell. In this experiment we observed bubble fragmentation through lamella division, occurring when bubbles are pinched against obstacles. This phenomenon, observed at the scale of individual bubbles, drastically modifies the bubble size distribution as the foam travels in the porous medium, and, therefore, the rheology of the foam flow. We now present a detailed characterization of this fragmentation process based on experiments, theory and numerical simulations. We measure and characterize the evolution of the bubble size distributions along the porous medium for several flow parameters. The observation of the bubble fragmentation around specific obstacles provides the bubbles fragmentation rates and the fragment size probability density function. These two ingredients and the measurement of the initial bubble size distribution allow modeling the process by a fragmentation equation, which is then solved either analytically (using some simplications) or numerically [2]. The dynamics of the bubble size distribution as inferred from the models is in very good agreement with the experimental data. References :[1

  13. Study on the generation of perfluorooctane sulfonate from the aqueous film-forming foam.

    PubMed

    Kishi, Takahiro; Arai, Mitsuru

    2008-11-15

    Perfluorooctane sulfonate (C(8)HF(17)SO(3)) and perfluorooctane acid (C(8)HF(15)O(2)) are artificial chemicals and have been used all over the world, mainly as water repellent agents, fluorochemical surfactants, coating agents, etc. However, perfluorooctane sulfonate and perfluorooctane acid are environmental contaminants because of their stability, bio-accumulativeness, and long-term persistence in the ecological environment. At the present day, they are diffused all over the world. Lately, this diffusion is viewed with suspicion and there is a movement towards their restriction, even if the environmental fate of them is still under investigation. Fluorochemical surfactants are key compounds in the aqueous film-forming foam (AFFF) formulations. AFFFs are used for massive conflagration such as industrial fire and petroleum fire because of their efficient fire control. On the other hand, a lot of AFFFs are used in case of massive conflagration and most of them enter ocean and groundwater. Actually, perfluorooctane sulfonate and perfluorooctane sulfonate related substances were detected from the fire-fighting facility of US forces. Therefore, there is the possibility of generating perfluorooctane sulfonate and perfluorooctane sulfonate related substances from fluorochemical surfactants in the AFFFs. In this study, activated sludge added AFFF were analyzed for perfluorooctane sulfonate and perfluorooctane acid with time. And the perfluorooctane sulfonate was directly detected after 2 days using LC-MS. This shows that AFFF can be decomposed perfluorooctane sulfonate by microorganisms easily. However, perfluorooctane sulfonate would not decompose at all. Additionally, activated sludge added N-polyoxyethylene-N-propyl perfluorooctane sulfonamide which is one of the fluorochemical surfactants used in the AFFF was analyzed for perfluorooctane sulfonate and perfluorooctane acid with time and the perfluorooctane sulfonate was detected too.

  14. Sorption of Perfluorochemicals to Matrices Relevant to Sites Impacted by Aqueous Film-Forming Foam

    NASA Astrophysics Data System (ADS)

    Sepulvado, J.; Higgins, C.

    2011-12-01

    Perfluorochemicals are a class of emerging contaminants consisting of fluorinated surfactants that are chemically and thermally stable and which contain a fluorocarbon tail that is both hydro- and oleophobic. Because of these unique properties, PFCs have a wide variety of uses including food paper packaging products, stain repellants, nonstick coatings, and aqueous film-forming foams (AFFF). At fire-training facilities, repeated application of AFFF is used to extinguish hydrocarbon fuel fires ignited for training purposes. The presence of perfluochemicals (PFCs) in groundwater as a result of repeated AFFF application at these facilities has been documented. Due to factors such as the recent push towards regulation of PFCs in drinking water, concerns have arisen about the fate of these compounds in the subsurface. Groundwater plumes containing PFC subclasses such as perfluorocarboxylic acids (PFCAs), perfluoroalkylsulfonates (PFAS), and fluorotelomer sulfonates (FtSs) in the μg/L to mg/L range have been detected. These plumes also may contain co-contaminants such as hydrocarbon fuel components and chlorinated solvents, some of which may exist as nonaqueous phase liquids (NAPL). This study examined the sorption of PFCs to soil and aquifer material across the concentration range applicable to AFFF-impacted sites (μg/L - mg/L) and looked at the impact of co-contaminants, including NAPL, on PFC sorption. PFC sorption was variable and indicated that similar to previous work on PFC sorption to sediment, subsurface PFC transport will depend on factors such as the sorbent organic carbon content, PFC subclass, solution chemistry, and PFC chain length.

  15. Development of multiphase CFD flow solver in OpenFOAM

    NASA Astrophysics Data System (ADS)

    Rollins, Chad; Luo, Hong; Dinh, Nam

    2016-11-01

    We are developing a pressure-based multiphase (Eulerian) CFD solver using OpenFOAM with Reynolds-averaged turbulence stress modeling. Our goal is the evaluation and improvement of the current OpenFOAM two-fluid (Eulerian) solver in boiling channels with a motivation to produce a more consistent modeling and numerics treatment. The difficulty lies in the prescense of the many forces and models that are tightly non-linearly coupled in the solver. Therefore, the solver platform will allow not only the modeling, but the tracking as well, of the effects of the individual components (various interfacial forces/heat transfer models) and their interactions. This is essential for the development of a robust and efficient solution method. There has be a lot of work already performed in related areas that generally indicates a lack of robustness of the solution methods. The objective here is therefore to identify and develop remedies for numerical/modeling issues through a systematic approach to verification and validation, taking advantage of the open source nature of OpenFOAM. The presentation will discuss major findings, and suggest strategies for robust and consistent modeling (probably, a more consistent treatment of heat transfer models with two-fluid models in the near-wall cells).

  16. Experimental And Analytical Study Of Heat Transfer And Fluid Flow Through Aluminum Foams

    NASA Astrophysics Data System (ADS)

    Mancin, Simone; Zilio, Claudio; Rossetto, Luisa; Cavallini, Alberto

    2010-05-01

    This paper aims at investigating the air heat transfer and fluid flow through eight Aluminum open cell foam samples with different number of pores per linear inch (PPI ranging between 5 and 40), almost constant porosity (around 0.92-0.93) and different foam core heights (20 and 40 mm). The experimental heat transfer coefficient and pressure drop measurements have been collected in a test rig built at Dipartimento di Fisica Tecnica of the University of Padova. Three different heat fluxes have been imposed: 25.0, 32.5 and 40.0 kW m-2 and the air mass flow rate has been varied between 0.005 and 0.025 kg s-1, with air approach velocity between 2 and 5 m s-1. The effect of the foam height on the heat transfer has been experimentally analysed. Finally, the pressure drop measurements have been compared against an analytical model suggested in the open literature.

  17. Particle stabilized aqueous foams at different length scales: synergy between silica particles and alkylamines.

    PubMed

    Carl, Adrian; Bannuscher, Anne; von Klitzing, Regine

    2015-02-10

    Nanoparticles can be efficient foaming agents. Yet, the detailed mechanisms of foam stabilization by these particles remain unclear. In most cases, the foamability and foam stability of a system have to be determined empirically. We used a multiscale approach to reveal how the microscopic properties of the nanoparticle dispersion are translated into their foaming behavior at the macroscopic scale. As a model system we used silica nanoparticles that were hydrophobized by the in situ adsorption of short-chain alkylamines of chain length C5 to C8. We used fluorescence spectroscopy and electrophoretic mobility measurements to characterize the bulk behavior of the nanoparticles with adsorbed amines. The interfacial behavior was probed by compressing particle monolayers while monitoring the surface tension. The macroscopic foamability and foam stability were evaluated. There are strong correlations between the system properties at all length scales. The most prominent effects are observed at a critical bulk concentration of amines at which the nanoparticles start to aggregate due to hydrophobic interactions. Our study shows how the foam properties are related to the features of the bulk dispersions and to the ordering of particles at the air/water interface. The present results help to understand the surfactant concentration dependent stages of foaming behavior of in situ hydrophobized nanoparticles.

  18. Foam clogging.

    PubMed

    Rouyer, F; Haffner, B; Louvet, N; Khidas, Y; Pitois, O

    2014-09-28

    To what extent are aqueous foams prone to clogging? Foam permeability is measured as a function of particulate loading (trapped hydrophilic particles) under conditions where the particle to bubble size ratio is allowed to increase when the number of particles per bubble is fixed. In addition to experiments performed on the foam scale, we investigated experimentally and numerically the hydrodynamic resistance of a single foam node loaded with one particle. It is shown that, with respect to solid porous media, aqueous foams clog more efficiently due to two reasons: (i) the deformation of interfaces allows for larger particles to be incorporated within the interstitial network and (ii) the interfacial mobility contributes to lowering of the reduced permeability.

  19. The effect of plastic rearrangements on the flow of two-dimensional wet foam.

    PubMed

    Jing, Zefeng; Wang, Shuzhong; Lv, Mingming; Wang, Zhiguo; Luo, Xiangrong

    2015-04-21

    The effect of the elementary plastic events on the flow behavior of the two-dimensional wet foam is investigated by quasistatic simulation on the bubble scale. The position where the plastic event occurs is traced by recording the coordinate at which two bubbles separate in the simulation. A localized shear band is found, and the width of this band increases with the increase of foam quality. From the displacement fields of these bubbles, it shows that the T1 plastic events can give rise to an increase in local bubble displacements due to the separation between these bubbles. The average relative pressure as well as normal stress difference of bubbles increases with the flow of foam in the initial elastic domain and then decreases as the elastic domain turns into the plastic domain. In the plastic domain, the plastic events rearrange the local structure of foam, which leads to decreasing both the average pressure and the normal stress difference. Additionally, the wall slip of foam is discussed in the simulation as well. The width of the localized shear band is narrower under the slip boundary condition. Meanwhile, the plastic events occurring between the first and second layers of bubbles change the pulling force of the films near the wall and cause an instantaneous increase in the slip velocity.

  20. Halloysite nanotube with fluorinated lumen: non-foaming nanocontainer for storage and controlled release of oxygen in aqueous media.

    PubMed

    Cavallaro, Giuseppe; Lazzara, Giuseppe; Milioto, Stefana; Palmisano, Giovanni; Parisi, Filippo

    2014-03-01

    Halloysite clay nanotubes were selectivity modified by adsorbing perfluoroalkylated anionic surfactants at the inner surface. The modified nanotubes formed kinetically stable dispersions due to the enhanced electrostatic repulsions exercised between the particles. We proved that the modified nanotubes can be used as non-foaming oxygen nanocontainers in aqueous media. The gas release from supersaturated dispersions can be controlled by external stimuli and system composition. In conclusion, we managed to put forward an easy strategy to develop smart materials from natural nanoclays, which can endow important applications like the storage and delivery of gas.

  1. Aqueous Flow Measured by Fluorophotometry in the Mouse.

    PubMed

    Toris, Carol B; Fan, Shan; Johnson, Thomas V; Camras, Lucinda J; Hays, Cassandra L; Liu, Hong; Ishimoto, Bruce M

    2016-07-01

    A fluorophotometer designed to measure aqueous flow in murine eyes was tested with artificial fluorescein chambers and in live mice with different anesthesia regimens, aqueous flow suppressants, and an anterior chamber cannulation method. Two hours following topical fluorescein application, one group of CD-1 mice was anesthetized with ketamine/xylazine, 2,2,2-tribromoethanol, or ketamine alone. Cornea and anterior chamber fluorescein concentrations were measured periodically for 60 to 90 minutes by fluorophotometric scans to calculate aqueous flow. Later, a subgroup of mice underwent aqueous flow measurement by anterior chamber cannulation. A third group was treated with timolol, dorzolamide, and vehicle in a crossover manner 1 hour prior to fluorophotometric scans. Aqueous flow with ketamine/xylazine anesthesia (0.09 ± 0.05 μL/min, mean ± SD, n = 24) was slower than with tribromoethanol or ketamine alone (P < 0.001). Timolol reduced aqueous flow from 0.20 ± 0.07 μL/min to 0.07 ± 0.03 μL/min (P = 0.001) under tribromoethanol anesthesia and from 0.14 ± 0.03 μL/min to 0.10 ± 0.02 μL/min (P = 0.004) under ketamine anesthesia but not under ketamine/xylazine anesthesia. Dorzolamide reduced aqueous flow from 0.09 ± 0.03 to 0.06 ± 0.03 μL/min (P = 0.04) under ketamine/xylazine anesthesia. Aqueous flow by anterior chamber cannulation (0.20 ± 0.13 μL/min) was greater (P = 0.05) than by fluorophotometry (0.09 ± 0.07 μL/min). A new noninvasive fluorophotometric method detected effects of general anesthesia and known aqueous suppressants on aqueous flow in mice. Aqueous flow measured by fluorophotometry was slower than by cannulation, and was technically easier with less variability. The mouse fluorophotometer is useful for repeated measurements of aqueous flow in the murine eye making crossover and longitudinal studies possible.

  2. Aqueous Flow Measured by Fluorophotometry in the Mouse

    PubMed Central

    Toris, Carol B.; Fan, Shan; Johnson, Thomas V.; Camras, Lucinda J.; Hays, Cassandra L.; Liu, Hong; Ishimoto, Bruce M.

    2016-01-01

    Purpose A fluorophotometer designed to measure aqueous flow in murine eyes was tested with artificial fluorescein chambers and in live mice with different anesthesia regimens, aqueous flow suppressants, and an anterior chamber cannulation method. Methods Two hours following topical fluorescein application, one group of CD-1 mice was anesthetized with ketamine/xylazine, 2,2,2-tribromoethanol, or ketamine alone. Cornea and anterior chamber fluorescein concentrations were measured periodically for 60 to 90 minutes by fluorophotometric scans to calculate aqueous flow. Later, a subgroup of mice underwent aqueous flow measurement by anterior chamber cannulation. A third group was treated with timolol, dorzolamide, and vehicle in a crossover manner 1 hour prior to fluorophotometric scans. Results Aqueous flow with ketamine/xylazine anesthesia (0.09 ± 0.05 μL/min, mean ± SD, n = 24) was slower than with tribromoethanol or ketamine alone (P < 0.001). Timolol reduced aqueous flow from 0.20 ± 0.07 μL/min to 0.07 ± 0.03 μL/min (P = 0.001) under tribromoethanol anesthesia and from 0.14 ± 0.03 μL/min to 0.10 ± 0.02 μL/min (P = 0.004) under ketamine anesthesia but not under ketamine/xylazine anesthesia. Dorzolamide reduced aqueous flow from 0.09 ± 0.03 to 0.06 ± 0.03 μL/min (P = 0.04) under ketamine/xylazine anesthesia. Aqueous flow by anterior chamber cannulation (0.20 ± 0.13 μL/min) was greater (P = 0.05) than by fluorophotometry (0.09 ± 0.07 μL/min). Conclusions A new noninvasive fluorophotometric method detected effects of general anesthesia and known aqueous suppressants on aqueous flow in mice. Aqueous flow measured by fluorophotometry was slower than by cannulation, and was technically easier with less variability. The mouse fluorophotometer is useful for repeated measurements of aqueous flow in the murine eye making crossover and longitudinal studies possible. PMID:27447085

  3. Foam drainage in the presence of solid particles.

    PubMed

    Wang, J; Nguyen, A V

    2016-03-28

    We conducted forced drainage experiments to study the liquid flow within the foams stabilized by a cationic surfactant (CTAB) in the presence of partially hydrophobic silica particles. The results show that the presence of solid particles, even when present in small amounts (0.0932 g L(-1) foam), can significantly decrease the foam permeability. The scaling behaviour (power law) between the drainage velocity and the imposed flow rate indicates that the presence of solid particles in the foams triggers a transition of the foam drainage regime from a node-dominated regime to a Plateau border-dominated regime. We applied two foam drainage equations for aqueous foams to simulate the experimental data and interpret the transition. The simulation results show that the presence of solid particles in the foams increases the rigidity of the interfaces and the viscous losses in the channels (the Plateau borders) of the foams, and decreases the foam permeability. We also generalize the theory for the effects of unattached hydrophilic particles on foam drainage by considering the effects of hydrophobicity and concentration of solid particles on the confinement of foam networks. This study explores liquid drainage in three-phase foams and is relevant to the field of hydrophobic particle separation by froth flotation, in which the wash water is commonly applied to the froth layer to improve the product grade.

  4. Electromagnetic induction of foam-based nanoscale zerovalent iron (NZVI) particles to thermally enhance non-aqueous phase liquid (NAPL) volatilization in unsaturated porous media: Proof of concept.

    PubMed

    Srirattana, Supawan; Piaowan, Kitsanateen; Lowry, Gregory V; Phenrat, Tanapon

    2017-09-01

    Nanoscale zerovalent iron (NZVI) is a promising remediation agent for volatile organic compound (VOC) contamination in saturated sub-surfaces, but is rarely applied to the vadose zone as there are not enough water molecules in the unsaturated zone to participate in reductive dechlorination. In this study, we evaluated the possibility of using foam as a carrying vehicle to emplace NZVI in unsaturated porous media followed by the application of low frequency-electromagnetic field (LF-EMF) to enhance VOC volatilization in laboratory batch reactors. We found that the optimal condition for generating foam-based NZVI (F-NZVI) was using sodium lauryl ether sulfate (SLES) at a concentration of 3% (w/w) and a N2 flow rate of 500 mL/min. Also, F-NZVI could carry as much as 41.31 g/L of NZVI in the liquid phase of the foam and generate heat to raise ΔT to 77 °C in 15 min under an applied LF-EMF (150 kHz and 13 A). Under these conditions, F-NZVI together with LF-EMF enhanced trichloroethylene (TCE) volatilization from TCE-dense non-aqueous phase liquid (DNAPL) in unsaturated sand by 39.51 ± 6.59-fold compared to reactors without LF-EMF application. This suggested that using F-NZVI together with LF-EMF could theoretically be an alternative to radio frequency heating (RFH) as it requires a much lower irradiation frequency (336-fold lower), which should result in significantly lower capital and operational costs compared to RFH. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Foam Transport in Porous Media - A Review

    SciTech Connect

    Zhang, Z. F.; Freedman, Vicky L.; Zhong, Lirong

    2009-11-11

    transport of foam in porous media is complicated in that the number of lamellae present governs flow characteristics such as viscosity, relative permeability, fluid distribution, and interactions between fluids. Hence, foam is a non-Newtonian fluid. During transport, foam destruction and formation occur. The net result of the two processes determines the foam texture (i.e., bubble density). Some of the foam may be trapped during transport. According to the impacts of the aqueous and gas flow rates, foam flow generally has two regimes – weak and strong foam. There is also a minimum pressure gradient to initiate foam flow and a critical capillary for foam to be sustained. Similar to other fluids, the transport of foam is described by Darcy’s law with the exception that the foam viscosity is variable. Three major approaches to modeling foam transport in porous media are the empirical, semi-empirical, and mechanistic methods. Mechanistic approaches can be complete in principal but may be difficult to obtain reliable parameters, whereas empirical and semi-empirical approaches can be limited by the detail used to describe foam rheology and mobility. Mechanistic approaches include the bubble population-balance model, the network/percolation theory, the catastrophe theory, and the filtration theory. Among these methods, all were developed for modeling polyhedral foam with the exception that the method based on the filtration theory was for the ball foam (microfoam).

  6. Effect of desmopressin on aqueous humor flow in humans.

    PubMed

    Viggiano, S R; Abboud, C F; Brubaker, R F

    1993-04-15

    The rate of aqueous humor flow was studied in 17 human subjects with neurogenic diabetes insipidus. Flow was measured by fluorophotometry on two consecutive afternoons. The first day, subjects used desmopressin to control their diuresis; on the second day, subjects did not use desmopressin and had uncontrolled diuresis. On both days, one eye was treated with the beta-adrenergic antagonist, timolol. With desmopressin, the rate of aqueous humor flow in the untreated eye was 2.53 +/- 0.79 microliters/min (mean +/- standard deviation) and in the timolol-treated eye was 1.69 +/- 0.40 microliters/min. Without desmopressin, the rate of aqueous humor flow in the untreated eye was 2.34 +/- 0.69 microliters/min and in the timolol-treated eye was 1.53 +/- 0.43 microliters/min. Thus, the use of desmopressin was associated with a slightly higher rate of aqueous humor flow in both the normal and the beta-adrenergically inhibited eye (P = .05), and the suppression of aqueous humor flow associated with beta-adrenergic inhibition occurred with and without antidiuretic hormone (P < .001). The observed differences in aqueous humor flow on the two days could have been caused by a direct effect on the eye or to indirect effects, such as the change in plasma osmolality, which changed from 291 +/- 6 mOsm on the desmopressin day to 299 +/- 8 mOsm on the desmopressin-abstention day (P < .001).

  7. Anomalous ion effects on rupture and lifetime of aqueous foam films from monovalent salt solutions up to saturation concentration

    NASA Astrophysics Data System (ADS)

    Karakashev, S. I.; Nguyen, P. T.; Tsekov, R.; Hampton, M. A.; Nguyen, A. V.

    2008-09-01

    We report the effects of ions on rupture and lifetime of aqueous foam films formed from sodium chloride (NaCl), lithium chloride (LiCl), sodium acetate (NaAc), and sodium chlorate (NaClO 3) using microinterferometry. In the case of NaCl and LiCl, the foam films prepared from the salt solutions below 0.1 M were unstable they thinned until rupturing. The film lifetime measured from the first interferogram (appearing at a film thickness on the order of 500 nm) until the film rupture was only a second or so. However, relatively long lasting and nondraining films prepared from salt solutions above 0.1 M were observed. The film lifetime was significantly longer by 1 to 2 orders of magnitude, i.e., from 10 to 100 s. Importantly, both the film lifetime and the (average) thickness of the nondraining films increased with increasing salt concentration. This effect has not been observed with foam films stabilized by surfactants. The film lifetime and thickness also increased with increasing film radius. The films exhibited significant surface corrugations. The films with large radii often contained standing dimples. There was a critical film radius below which the films thinned until rupturing. In the cases of NaAc and NaClO 3, the films were unstable at all radii and salt concentrations they thinned until rupturing, ruling out the effect of solution viscosity on stabilizing the films.

  8. Magnetic Resonance Flow Velocity and Temperature Mapping of a Shape Memory Polymer Foam Device

    SciTech Connect

    Small IV, W; Gjersing, E; Herberg, J L; Wilson, T S; Maitland, D J

    2008-10-29

    Interventional medical devices based on thermally responsive shape memory polymer (SMP) are under development to treat stroke victims. The goals of these catheter-delivered devices include re-establishing blood flow in occluded arteries and preventing aneurysm rupture. Because these devices alter the hemodynamics and dissipate thermal energy during the therapeutic procedure, a first step in the device development process is to investigate fluid velocity and temperature changes following device deployment. A laser-heated SMP foam device was deployed in a simplified in vitro vascular model. Magnetic resonance imaging (MRI) techniques were used to assess the fluid dynamics and thermal changes associated with device deployment. Spatial maps of the steady-state fluid velocity and temperature change inside and outside the laser-heated SMP foam device were acquired. Though non-physiological conditions were used in this initial study, the utility of MRI in the development of a thermally-activated SMP foam device has been demonstrated.

  9. A study on high subsonic airfoil flows in relatively high Reynolds number by using OpenFOAM

    NASA Astrophysics Data System (ADS)

    Nakao, Shinichiro; Kashitani, Masashi; Miyaguni, Takeshi; Yamaguchi, Yutaka

    2014-04-01

    In the present study, numerical calculations of the flow-field around the airfoil model are performed by using the OpenFOAM in high subsonic flows. The airfoil model is NACA 64A010. The maximum thickness is 10 % of the chord length. The SonicFOAM and the RhoCentralFOAM are selected as the solver in high subsonic flows. The grid point is 158,000 and the Mach numbers are 0.277 and 0.569 respectively. The CFD data are compared with the experimental data performed by the cryogenic wind tunnel in the past. The results are as follows. The numerical results of the pressure coefficient distribution on the model surface calculated by the SonicFOAM solver showed good agreement with the experimental data measured by the cryogenic wind tunnel. And the data calculated by the SonicFOAM have the capability for the quantitative comparison of the experimental data at low angle of attack.

  10. Polyurethane foam loaded with sodium dodecylsulfate for the extraction of 'quat' pesticides from aqueous medium: Optimization of loading conditions.

    PubMed

    Vinhal, Jonas O; Lima, Claudio F; Cassella, Ricardo J

    2016-09-01

    The cationic herbicides paraquat, diquat and difenzoquat are largely used in different cultures worldwide. With this, there is an intrinsic risk of environmental contamination when these herbicides achieve natural waters. The goal of this work was to propose a novel and low-cost sorbent for the removal of the cited herbicides from aqueous medium. The proposed sorbent was prepared by loading polyurethane foam with sodium dodecylsulfate. The influence of several parameters (SDS concentration, HCl concentration and shaking time) on the loading process was investigated. The results obtained in this work demonstrated that all studied variables influenced the loading process, having significant effect on the extraction efficiency of the resulted PUF-SDS. At optimized conditions, the PUF was loaded by shaking 200mg of crushed foam with 200mL of a solution containing 5.0×10(-3)molL(-1) SDS and 0.25molL(-1) HCl, for 30min. The obtained PUF-SDS was efficient for removing the three herbicides from aqueous medium, achieving extraction percentages higher than 90%. The sorption process followed a pseudo second-order kinetics, which presented excellent predictive capacity of the amount of herbicide retained with time.

  11. On the influence of surfactant on the coarsening of aqueous foams.

    PubMed

    Briceño-Ahumada, Zenaida; Langevin, Dominique

    2017-06-01

    We review the coarsening process of foams made with various surfactants and gases, focusing on physico-chemical aspects. Several parameters strongly affect coarsening: foam liquid fraction and foam film permeability, this permeability depending on the surfactant used. Both parameters may evolve with time: the liquid fraction, due to gravity drainage, and the film permeability, due to the decrease of capillary pressure during bubble growth, and to the subsequent increase in film thickness. Bubble coalescence may enhance the bubble's growth rate, in which case the bubble polydispersity increases. The differences found between the experiments reported in the literature and between experiments and theories are discussed. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Experimental analysis of R134a flow boiling inside a 5 PPI copper foam

    NASA Astrophysics Data System (ADS)

    Diani, A.; Mancin, S.; Rossetto, L.

    2014-04-01

    Heat dissipation is one of the most important issues for the reliability of electronic equipment. Boiling can be a very efficient heat transfer mechanism when used to face with the electronic technology needs of efficient and compact heat sinks. Recently, cellular structured materials both stochastic and periodic, particularly open cell metal foams, have been proposed as possible enhanced surfaces to lower the junction temperatures at high heat fluxes. Up today, most of the research on metal foams only regards single phase flow, whereas the two phase flow is still almost unexplored. This paper presents an experimental study on the heat transfer of R134a during flow boiling inside a 5 PPI (Pores Per linear Inch) copper foam, which is 5 mm high, 10 mm wide and 200 mm long, and it is brazed on a 10 mm thick copper plate. The experimental measurements were carried out by imposing three different heat fluxes (50, 75, and 100 kW m-2) and by varying the refrigerant mass velocity between 50 and 200 kg m-2 s-1 and the vapour quality from 0.2 to 0.90, at constant saturation temperature (30°C). The effects of the refrigerant mass flow rate, heat flux and vapour quality on the heat transfer coefficient, dry out phenomenon, and pressure drop are studied.

  13. Periodic explosions by positive feedback in a rising foam column

    PubMed Central

    Zener, Clarence; Noriega, Jaime

    1982-01-01

    An aqueous foam rising adiabatically in a column suffers a drop in temperature. Under appropriate conditions, such a column periodically explodes. We here trace this explosion to the tight thermal coupling between the foam and its enclosing glass column. When the surface surfactant concentration is unbuffered by micelles, a positive feedback exists between the flow of heat from the walls into the foam and the thermal conductivity of the foam itself. In our highly expanded foam, heat is conducted through the foam cells' interior primarily by the heat-pipe effect. Such an effect is retarded by a dense layer of surfactant molecules. Heat absorption causes cell expansion, which, in a foam unbuffered by micelles, causes a reduction in surface concentration of surfactant molecules and, hence, in an increase in thermal conductivity. This interpretation of our observed periodic explosions is in agreement with all of our observations. PMID:16593192

  14. Two-dimensional plastic flow of foams and emulsions in a channel: experiments and simulations

    NASA Astrophysics Data System (ADS)

    Sbragaglia, Mauro; Andrea Scagliarini Collaboration; Benjamin Dollet Collaboration

    2015-11-01

    In order to understand the flow profiles of complex fluids, a crucial issue concerns the emergence of spatial correlations among plastic rearrangements exhibiting cooperativity flow behaviour at the macroscopic level. In this paper, the rate of plastic events in a Poiseuille flow is experimentally measured on a confined foam in a Hele-Shaw geometry. The correlation with independently measured velocity profiles is quantified by looking at the relationship between the localisation length of the velocity profiles and the localisation length of the spatial distribution of plastic events. To complement the cooperativity mechanisms studied in foam with those of other soft glassy systems, we compare the experiments with simulations of dense emulsions based on the lattice Boltzmann method, which are performed both with and without wall friction. Finally, unprecedented results on the distribution of the orientation of plastic events show that there is a non-trivial correlation with the underlying local shear strain. These features, not previously reported for a confined foam, lend further support to the idea that cooperativity mechanisms, originally invoked for concentrated emulsions (Goyon et al., Nature, vol. 454, 2008, pp. 84-87), have parallels in the behaviour of other soft glassy ma ERC Grant n.279004-DROEMU

  15. Evaluating the performance of the two-phase flow solver interFoam

    NASA Astrophysics Data System (ADS)

    Deshpande, Suraj S.; Anumolu, Lakshman; Trujillo, Mario F.

    2012-01-01

    The performance of the open source multiphase flow solver, interFoam, is evaluated in this work. The solver is based on a modified volume of fluid (VoF) approach, which incorporates an interfacial compression flux term to mitigate the effects of numerical smearing of the interface. It forms a part of the C + + libraries and utilities of OpenFOAM and is gaining popularity in the multiphase flow research community. However, to the best of our knowledge, the evaluation of this solver is confined to the validation tests of specific interest to the users of the code and the extent of its applicability to a wide range of multiphase flow situations remains to be explored. In this work, we have performed a thorough investigation of the solver performance using a variety of verification and validation test cases, which include (i) verification tests for pure advection (kinematics), (ii) dynamics in the high Weber number limit and (iii) dynamics of surface tension-dominated flows. With respect to (i), the kinematics tests show that the performance of interFoam is generally comparable with the recent algebraic VoF algorithms; however, it is noticeably worse than the geometric reconstruction schemes. For (ii), the simulations of inertia-dominated flows with large density ratios {\\sim }\\mathscr {O}(10^3) yielded excellent agreement with analytical and experimental results. In regime (iii), where surface tension is important, consistency of pressure-surface tension formulation and accuracy of curvature are important, as established by Francois et al (2006 J. Comput. Phys. 213 141-73). Several verification tests were performed along these lines and the main findings are: (a) the algorithm of interFoam ensures a consistent formulation of pressure and surface tension; (b) the curvatures computed by the solver converge to a value slightly (10%) different from the analytical value and a scope for improvement exists in this respect. To reduce the disruptive effects of spurious

  16. Drag enhancement of aqueous electrolyte solutions in turbulent pipe flow.

    PubMed

    Doherty, Andrew P; Spedding, Peter L; Chen, John J J

    2010-04-22

    Detailed experimental results are presented for both laminar and turbulent flow of aqueous solutions in pipes of different diameters. Nonelectrolytes, such as sugar solutions followed the normal Moody pressure loss curves. Drag enhancement was demonstrated for turbulent flow of aqueous electrolyte solutions but not for laminar flow. The increased pressure drop for turbulent electrolyte flow was attributed to an electroviscous effect and a theory was developed to explain the drag enhancement. The increased pressure drop for the turbulent region of flow was shown to depend on the Debye length in the laminar sublayer on the pipe wall. Reasonable predictions of the increasing drag were obtained for both 1:1 and 2:1 electrolyte solutions.

  17. Bioremediation of aqueous pollutants using biomass embedded in hydrophilic foam. Final report

    SciTech Connect

    Wilde, E.W.; Radway, J.C.; Santo Domingo, J.; Zingmark, R.G.; Whitaker, M.J.

    1996-12-31

    The major objective of this project was to examine the potential of a novel hydrophilic polyurethane foam as an immobilization medium for algal, bacteria, and other types of biomass, and to test the resulting foam/biomass aggregates for their use in cleaning up waters contaminated with heavy metals, radionuclides and toxic organic compounds. Initial investigations focused on the bioremoval of heavy metals from wastewaters at SRS using immobilized algal biomass. This effort met with limited success for reasons which included interference in the binding of biomass and target metals by various non-target constituents in the wastewater, lack of an appropriate wastewater at SRS for testing, and the unavailability of bioreactor systems capable of optimizing contact of target pollutants with sufficient biomass binding sites. Subsequent studies comparing algal, bacterial, fungal, and higher plant biomass demonstrated that other biomass sources were also ineffective for metal bioremoval under the test conditions. Radionuclide bioremoval using a Tc-99 source provided more promising results than the metal removal studies with the various types of biomass, and indicated that the alga Cyanidium was the best of the tested sources of biomass for this application. However, all of the biomass/foam aggregates tested were substantially inferior to a TEVA resin for removing Tc-99 in comparative testing. The authors also explored the use of hydrophilic polyurethane foam to embed Burkholderia cepacia, which is an efficient degrader of trichloroethylene (TCE), a contaminant of considerable concern at SRS and elsewhere. The embedded population proved to be incapable of growth on nutrient media, but retained respiratory activity. Lastly, the degradative capabilities of embedded G4 were examined. Phenol- or benzene-induced bacteria retained the ability to degrade TCE and benzene. The authors were successful in inducing enzyme activity after the organisms had already been embedded.

  18. Free drainage of aqueous foams: Container shape effects on capillarity and vertical gradients

    NASA Astrophysics Data System (ADS)

    Saint-Jalmes, A.; Vera, M. U.; Durian, D. J.

    2000-06-01

    The standard drainage equation applies only to foam columns of constant cross-sectional area. Here, we generalize to include the effects of arbitrary container shape and develop an exact solution for an exponential, "Eiffel Tower", sample. This geometry largely eliminates vertical wetness gradients, and hence capillary effects, and should permit a clean test of dissipation mechanisms. Agreement with experiment is not achieved at late times, however, highlighting the importance of both boundary conditions and coarsening.

  19. Aqueous carrier waveguide in a flow cytometer

    DOEpatents

    Mariella, R.P. Jr.; Engh, G. van den; Northrup, M.A.

    1995-12-12

    The liquid of a flow cytometer itself acts as an optical waveguide, thus transmitting the light to an optical filter/detector combination. This alternative apparatus and method for detecting scattered light in a flow cytometer is provided by a device which views and detects the light trapped within the optical waveguide formed by the flow stream. A fiber optic or other light collecting device is positioned within the flow stream. This provides enormous advantages over the standard light collection technique which uses a microscope objective. The signal-to-noise ratio is greatly increased over that for right-angle-scattered light collected by a microscope objective, and the alignment requirements are simplified. 6 figs.

  20. Aqueous carrier waveguide in a flow cytometer

    DOEpatents

    Mariella, Jr., Raymond P.; van den Engh, Gerrit; Northrup, M. Allen

    1995-01-01

    The liquid of a flow cytometer itself acts as an optical waveguide, thus transmitting the light to an optical filter/detector combination. This alternative apparatus and method for detecting scattered light in a flow cytometer is provided by a device which views and detects the light trapped within the optical waveguide formed by the flow stream. A fiber optic or other light collecting device is positioned within the flow stream. This provides enormous advantages over the standard light collection technique which uses a microscope objective. The signal-to-noise ratio is greatly increased over that for right-angle-scattered light collected by a microscope objective, and the alignment requirements are simplified.

  1. Structure and coarsening at the surface of a dry three-dimensional aqueous foam.

    PubMed

    Roth, A E; Chen, B G; Durian, D J

    2013-12-01

    We utilize total-internal reflection to isolate the two-dimensional surface foam formed at the planar boundary of a three-dimensional sample. The resulting images of surface Plateau borders are consistent with Plateau's laws for a truly two-dimensional foam. Samples are allowed to coarsen into a self-similar scaling state where statistical distributions appear independent of time, except for an overall scale factor. There we find that statistical measures of side number distributions, size-topology correlations, and bubble shapes are all very similar to those for two-dimensional foams. However, the size number distribution is slightly broader, and the shapes are slightly more elongated. A more obvious difference is that T2 processes now include the creation of surface bubbles, due to rearrangement in the bulk, and von Neumann's law is dramatically violated for individual bubbles. But nevertheless, our most striking finding is that von Neumann's law appears to holds on average, namely, the average rate of area change for surface bubbles appears to be proportional to the number of sides minus six, but with individual bubbles showing a wide distribution of deviations from this average behavior.

  2. Structure and coarsening at the surface of a dry three-dimensional aqueous foam

    NASA Astrophysics Data System (ADS)

    Roth, A. E.; Chen, B. G.; Durian, D. J.

    2013-12-01

    We utilize total-internal reflection to isolate the two-dimensional surface foam formed at the planar boundary of a three-dimensional sample. The resulting images of surface Plateau borders are consistent with Plateau's laws for a truly two-dimensional foam. Samples are allowed to coarsen into a self-similar scaling state where statistical distributions appear independent of time, except for an overall scale factor. There we find that statistical measures of side number distributions, size-topology correlations, and bubble shapes are all very similar to those for two-dimensional foams. However, the size number distribution is slightly broader, and the shapes are slightly more elongated. A more obvious difference is that T2 processes now include the creation of surface bubbles, due to rearrangement in the bulk, and von Neumann's law is dramatically violated for individual bubbles. But nevertheless, our most striking finding is that von Neumann's law appears to holds on average, namely, the average rate of area change for surface bubbles appears to be proportional to the number of sides minus six, but with individual bubbles showing a wide distribution of deviations from this average behavior.

  3. Attraction-induced jamming in the flow of foam through a channel.

    PubMed

    Menon, Karthik; Govindarajan, Rama; Tewari, Shubha

    2016-10-07

    We study the flow of a pressure-driven foam through a straight channel using numerical simulations, and examine the effects of a tuneable attractive potential between bubbles. We show that the effect of an attractive potential is to introduce a regime of jamming and stick-slip flow in a channel, and report on the behaviour resulting from varying the strength of the attraction. We find that there is a force threshold below which the flow jams, and upon further increasing the driving force, a crossover from intermittent (stick-slip) to smooth flow is observed. This threshold force below which the foam jams increases linearly with the strength of the attractive potential. By examining the spectra of energy fluctuations, we show that stick-slip flow is characterized by low frequency rearrangements and strongly local behaviour, whereas steady flow shows a broad spectrum of energy drop events and collective behaviour. Our work suggests that the stick-slip and the jamming regimes occur due to the increased stabilization of contact networks by the attractive potential - as the strength of attraction is increased, bubbles are increasingly trapped within networks, and there is a decrease in the number of contact changes.

  4. Numerical simulation of flow around a simplified high-speed train model using OpenFOAM

    NASA Astrophysics Data System (ADS)

    Ishak, I. A.; Ali, M. S. M.; Shaikh Salim, S. A. Z.

    2016-10-01

    Detailed understanding of flow physics on the flow over a high-speed train (HST) can be accomplished using the vast information obtained from numerical simulation. Accuracy of any simulation in solving and analyzing problems related to fluid flow is important since it measures the reliability of the results. This paper describes a numerical simulation setup for the flow around a simplified model of HST that utilized open source software, OpenFOAM. The simulation results including pressure coefficient, drag coefficient and flow visualization are presented and they agreed well with previously published data. This shows that OpenFOAM software is capable of simulating fluid flows around a simplified HST model. Additionally, the wall functions are implemented in order to minimize the overall number of grid especially near the wall region. This resulted in considerably smaller numbers of mesh resolution used in the current study compared to previous work, which leads to achievement of much reasonable time simulation and consequently reduces the total computational effort without affecting the final outcome.

  5. Enhanced Oil Recovery: Aqueous Flow Tracer Measurement

    SciTech Connect

    Joseph Rovani; John Schabron

    2009-02-01

    A low detection limit analytical method was developed to measure a suite of benzoic acid and fluorinated benzoic acid compounds intended for use as tracers for enhanced oil recovery operations. Although the new high performance liquid chromatography separation successfully measured the tracers in an aqueous matrix at low part per billion levels, the low detection limits could not be achieved in oil field water due to interference problems with the hydrocarbon-saturated water using the system's UV detector. Commercial instrument vendors were contacted in an effort to determine if mass spectrometry could be used as an alternate detection technique. The results of their work demonstrate that low part per billion analysis of the tracer compounds in oil field water could be achieved using ultra performance liquid chromatography mass spectrometry.

  6. Analytical and Numerical Modeling of Fluid Flow and Heat Transfer through Open-Cell Metal Foam Heat Exchangers

    NASA Astrophysics Data System (ADS)

    Taheri, Mehrdad

    In this thesis analytical and numerical investigations of fluid flow and heat transfer through open cell metal foam heat exchangers are presented. Primarily, different representative unit cell approximations, i.e, tetrakaidecahedron, dodecahedron and cubic are discussed. By applying the thermal resistance analogy, a novel formulation for evaluation of the effective thermal conductivity of metal foams is proposed. The model improves previous models based on cubic or hexagonal cells. By using computer tomography images of a nickel foam sample a realistic 3D geometry is created and the foam's geometrical properties (i.e., porosity and surface area to volume ratio) and effective thermal conductivity are obtained. By using the experimentally found values of permeability, Forchheimer coefficient and solid-fluid interfacial convection coefficient, mathematical models for fluid flow and heat transfer in metal foams are developed. Two different assumptions: local thermal equilibrium (LTE) and local thermal non-equilibrium (LTNE), are used. LTNE yields more accurate results. A three-dimensional computational fluid dynamics (CFD) model of metal foam is made and validated against the experimental data for a square cross sectional nickel foam heat exchanger channel heated from the side walls while cooling air passes through the foam. The simulations are carried out for constant temperature or heat flux and different foam materials with pore densities of 10 and 40 pores per inch. The results show that the bonding of the foam to the walls has a considerable impact on the heat transfer rate. Convective heat transfer coefficients in terms of Nusselt number as functions of Reynolds number are also obtained. The design and CFD modeling of metal foam cross flow heat exchangers are also discussed. The results indicate both effectiveness and number of transfer units (NTU) for the metal foam heat exchangers are higher than those of a hollow channel; however, the effectiveness-NTU curves

  7. Wall slipping behavior of foam with nanoparticle-armored bubbles and its flow resistance factor in cracks.

    PubMed

    Lv, Qichao; Li, Zhaomin; Li, Binfei; Husein, Maen; Shi, Dashan; Zhang, Chao; Zhou, Tongke

    2017-07-11

    In this work, wall slipping behavior of foam with nanoparticle-armored bubbles was first studied in a capillary tube and the novel multiphase foam was characterized by a slipping law. A crack model with a cuboid geometry was then used to compare with the foam slipping results from the capillary tube and also to evaluate the flow resistance factor of the foam. The results showed that the slipping friction force F FR in the capillary tube significantly increased by addition of modified SiO2 nanoparticles, and an appropriate power law exponents by fitting F FR vs. Capillary number, Ca, was 1/2. The modified nanoparticles at the surface were bridged together and formed a dense particle "armor" surrounding the bubble, and the interconnected structures of the "armor" with strong steric integrity made the surface solid-like, which was in agreement with the slip regime associated with rigid surface. Moreover, as confirmed by 3D microscopy, the roughness of the bubble surface increased with nanoparticle concentration, which in turn increased the slipping friction force. Compared with pure SDBS foam, SDBS/SiO2 foam shows excellent stability and high flow resistance in visual crack. The resistance factor of SiO2/SDBS foam increased as the wall surface roughness increased in core cracks.

  8. Identification of the full anisotropic flow resistivity tensor for multiple glass wool and melamine foam samples.

    PubMed

    Van der Kelen, Christophe; Göransson, Peter

    2013-12-01

    The flow resistivity tensor, which is the inverse of the viscous permeability tensor, is one of the most important material properties for the acoustic performance of porous materials used in acoustic treatments. Due to the manufacturing processes involved, these porous materials are most often geometrically anisotropic on a microscopic scale, and for demanding applications, there is a need for improved characterization methods. This paper discusses recent refinements of a method for the identification of the anisotropic flow resistivity tensor. The inverse estimation is verified for three fictitious materials with different degrees of anisotropy. Measurements are performed on nine glass wool samples and seven melamine foam samples, and the anisotropic flow resistivity tensors obtained are validated by comparison to measurements performed on uni-directional cylindrical samples, extracted from the same, previously measured cubic samples. The variability of flow resistivity in the batch of material from which the glass wool is extracted is discussed. The results for the melamine foam suggest that there is a relation between the direction of highest flow resistivity, and the rise direction of the material.

  9. Comparison of Two-Phase Pipe Flow in OpenFOAM with a Mechanistic Model

    NASA Astrophysics Data System (ADS)

    Shuard, Adrian M.; Mahmud, Hisham B.; King, Andrew J.

    2016-03-01

    Two-phase pipe flow is a common occurrence in many industrial applications such as power generation and oil and gas transportation. Accurate prediction of liquid holdup and pressure drop is of vast importance to ensure effective design and operation of fluid transport systems. In this paper, a Computational Fluid Dynamics (CFD) study of a two-phase flow of air and water is performed using OpenFOAM. The two-phase solver, interFoam is used to identify flow patterns and generate values of liquid holdup and pressure drop, which are compared to results obtained from a two-phase mechanistic model developed by Petalas and Aziz (2002). A total of 60 simulations have been performed at three separate pipe inclinations of 0°, +10° and -10° respectively. A three dimensional, 0.052m diameter pipe of 4m length is used with the Shear Stress Transport (SST) k - ɷ turbulence model to solve the turbulent mixtures of air and water. Results show that the flow pattern behaviour and numerical values of liquid holdup and pressure drop compare reasonably well to the mechanistic model.

  10. Magnetic resonance flow velocity and temperature mapping of a shape memory polymer foam device

    PubMed Central

    2009-01-01

    Background Interventional medical devices based on thermally responsive shape memory polymer (SMP) are under development to treat stroke victims. The goals of these catheter-delivered devices include re-establishing blood flow in occluded arteries and preventing aneurysm rupture. Because these devices alter the hemodynamics and dissipate thermal energy during the therapeutic procedure, a first step in the device development process is to investigate fluid velocity and temperature changes following device deployment. Methods A laser-heated SMP foam device was deployed in a simplified in vitro vascular model. Magnetic resonance imaging (MRI) techniques were used to assess the fluid dynamics and thermal changes associated with device deployment. Results Spatial maps of the steady-state fluid velocity and temperature change inside and outside the laser-heated SMP foam device were acquired. Conclusions Though non-physiological conditions were used in this initial study, the utility of MRI in the development of a thermally-activated SMP foam device has been demonstrated. PMID:20043833

  11. Model of Turbulent Flow of Rheological Solutions of Foaming Agents in Channels of Automatic Fire-Extinguishing Systems

    NASA Astrophysics Data System (ADS)

    Polevoda, I. I.; Karpenchuk, I. V.; Striganova, M. Yu.; Shatilo, É. É.

    2015-01-01

    A model of turbulent flow of a rheological solution of a foaming agent in a cylindrical channel of an automatic fire-extinguishing system is proposed; this model allows for the viscous stresses produced in the region of hydraulic roughness of the channel. Integral equations are obtained for calculation of the flow velocity and rate of flow of the foaming agent in the indicated channel, and also of the hydraulic resistance and head loss in it. Recommendations on practical use of the proposed theoretical model have been developed.

  12. Organic non-aqueous cation-based redox flow batteries

    DOEpatents

    Jansen, Andrew N.; Vaughey, John T.; Chen, Zonghai; Zhang, Lu; Brushett, Fikile R.

    2016-03-29

    The present invention provides a non-aqueous redox flow battery comprising a negative electrode immersed in a non-aqueous liquid negative electrolyte, a positive electrode immersed in a non-aqueous liquid positive electrolyte, and a cation-permeable separator (e.g., a porous membrane, film, sheet, or panel) between the negative electrolyte from the positive electrolyte. During charging and discharging, the electrolytes are circulated over their respective electrodes. The electrolytes each comprise an electrolyte salt (e.g., a lithium or sodium salt), a transition-metal free redox reactant, and optionally an electrochemically stable organic solvent. Each redox reactant is selected from an organic compound comprising a conjugated unsaturated moiety, a boron cluster compound, and a combination thereof. The organic redox reactant of the positive electrolyte is selected to have a higher redox potential than the redox reactant of the negative electrolyte.

  13. Drainage dynamics controlled by corner flow: Application of the foam drainage equation

    NASA Astrophysics Data System (ADS)

    Hoogland, Frouke; Lehmann, Peter; Or, Dani

    2016-11-01

    In fast drainage processes water is retained behind the front, defining the plant available water and hydraulic properties of the unsaturated region. In this study we show that the foam drainage equation (FDE) can be applied to predict macroscopic drainage dynamics behind the front because a network of liquid channels controls the liquid flow in both foams and crevices of the pore space. To predict drainage rates at the Darcy scale the FDE is solved numerically after adapting channel geometries and boundary conditions to experimental conditions. The FDE results were in good agreement with measured flow rates behind a drainage front in coarse and fine sand. A notable exception was rapid drainage from fine sand where saturated pore clusters persisted after front passage and drained faster compared to FDE predictions. The dominance of corner capillary flows implied by the good agreement with the FDE formulation could improve the scientific underpinning of the unsaturated hydraulic conductivity function and offers a more realistic view of the geometry of pathways for colloid and pathogen transport in unsaturated media.

  14. Experimentally observed flows inside inkjet-printed aqueous rivulets

    NASA Astrophysics Data System (ADS)

    Bromberg, Vadim; Singler, Timothy

    2013-11-01

    Understanding the flow inside sessile liquid masses of different shapes is important in a variety of solution-based material deposition and patterning processes. We investigated the shape evolution and internal flow of inkjet-printed aqueous rivulets of finite length using optical microscopy. Rivulets were formed by printing a pre-determined number of drops at controlled frequency and spatial overlap. Capillary-driven rivulet breakup into individual drops was inhibited by chemical modification of substrates that resulted in controlled contact angle hysteresis with zero static receding contact angle. A variety of novel capillary- and evaporatively-driven flows were identified using fluorescent particles as flow tracers. Flow regimes were investigated as a function of advancing contact angle, deposition parameters, and fluid properties.

  15. rhoCentralRfFoam: An OpenFOAM solver for high speed chemically active flows - Simulation of planar detonations -

    NASA Astrophysics Data System (ADS)

    Gutiérrez Marcantoni, L. F.; Tamagno, J.; Elaskar, S.

    2017-10-01

    A new solver developed within the framework of OpenFOAM 2.3.0, called rhoCentralRfFoam which can be interpreted like an evolution of rhoCentralFoam, is presented. Its use, performing numerical simulations on initiation and propagation of planar detonation waves in combustible mixtures H2-Air and H2-O2-Ar, is described. Unsteady one dimensional (1D) Euler equations coupled with sources to take into account chemical activity, are numerically solved using the Kurganov, Noelle and Petrova second order scheme in a domain discretized with finite volumes. The computational code can work with any number of species and its corresponding reactions, but here it was tested with 13 chemically active species (one species inert), and 33 elementary reactions. A gaseous igniter which acts like a shock-tube driver, and powerful enough to generate a strong shock capable of triggering exothermic chemical reactions in fuel mixtures, is used to start planar detonations. The following main aspects of planar detonations are here, treated: induction time of combustible mixtures cited above and required mesh resolutions; convergence of overdriven detonations to Chapman-Jouguet states; detonation structure (ZND model); and the use of reflected shocks to determine induction times experimentally. The rhoCentralRfFoam code was verified comparing numerical results and it was validated, through analytical results and experimental data.

  16. Electrochemical treatment of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) in groundwater impacted by aqueous film forming foams (AFFFs).

    PubMed

    Schaefer, Charles E; Andaya, Christina; Urtiaga, Ana; McKenzie, Erica R; Higgins, Christopher P

    2015-09-15

    Laboratory experiments were performed to evaluate the use of electrochemical treatment for the decomposition of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS), as well as other perfluoroalkyl acids (PFAAs), in aqueous film forming foam (AFFF)-impacted groundwater collected from a former firefighter training area and PFAA-spiked synthetic groundwater. Using a commercially-produced Ti/RuO2 anode in a divided electrochemical cell, PFOA and PFOS decomposition was evaluated as a function of current density (0-20 mA/cm(2)). Decomposition of both PFOA and PFOS increased with increasing current density, although the decomposition of PFOS did not increase as the current density was increased above 2.5 mA/cm(2). At a current density of 10 mA/cm(2), the first-order rate constants, normalized for current density and treatment volume, for electrochemical treatment of both PFOA and PFOS were 46 × 10(-5) and 70 × 10(-5) [(min(-1)) (mA/cm(2))(-1) (L)], respectively. Defluorination was confirmed for both PFOA and PFOS, with 58% and 98% recovery as fluoride, respectively (based upon the mass of PFOA and PFOS degraded). Treatment of other PFAAs present in the groundwater also was observed, with shorter chain PFAAs generally being more recalcitrant. Results highlight the potential for electrochemical treatment of PFAAs, particularly PFOA and PFOS, in AFFF-impacted groundwater. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Temporal monitoring of perfluorooctane sulfonate accumulation in aquatic biota downstream of historical aqueous film forming foam use areas.

    PubMed

    Lanza, Heather A; Cochran, Rebecca S; Mudge, Joseph F; Olson, Adric D; Blackwell, Brett R; Maul, Jonathan D; Salice, Christopher J; Anderson, Todd A

    2017-08-01

    Perfluoroalkyl substances (PFAS) have recently received increased research attention, particularly concerning aquatic organisms and in regions of exposure to aqueous film forming foams (AFFFs). Air Force bases historically applied AFFFs in the interest of fire training exercises and have since expressed concern for PFAS contamination in biota from water bodies surrounding former fire training areas. Six PFAS were monitored, including perfluorooctane sulfonate (PFOS), in aquatic species from 8 bayou locations at Barksdale Air Force Base in Bossier City, Louisiana (USA) over the course of 1 yr. The focus was to evaluate temporal and spatial variability in PFAS concentrations from historic use of AFFF. The PFOS concentrations in fish peaked in early summer, and also increased significantly downstream of former fire training areas. Benthic organisms had lower PFOS concentrations than pelagic species, contrary to previous literature observations. Bioconcentration factors varied with time but were reduced compared with previously reported literature values. The highest concentration of PFOS in whole fish was 9349 ng/g dry weight, with 15% of samples exceeding what is believed to be the maximum whole fish concentration reported to date of 1500 ng/g wet weight. Further studies are ongoing, to measure PFAS in larger fish and tissue-specific partitioning data to compare with the current whole fish values. The high concentrations presently observed could have effects on higher trophic level organisms in this system or pose a potential risk to humans consuming contaminated fish. Environ Toxicol Chem 2017;36:2022-2029. © 2016 SETAC. © 2016 SETAC.

  18. Aerobic biodegradation of 2 fluorotelomer sulfonamide-based aqueous film-forming foam components produces perfluoroalkyl carboxylates.

    PubMed

    D'Agostino, Lisa A; Mabury, Scott A

    2017-08-01

    The biodegradation of 2 common fluorotelomer surfactants used in aqueous film forming foams (AFFFs), 6:2 fluorotelomer sulfonamide alkylamine (FTAA) and 6:2 fluorotelomer sulfonamide alkylbetaine (FTAB), was investigated over 109 d with aerobic wastewater-treatment plant (WWTP) sludge. Results show that biodegradation of 6:2 FTAA and 6:2 FTAB produces 6:2 fluorotelomer alcohol (FTOH), 6:2 fluorotelomer carboxylic acid (FTCA), 6:2 fluorotelomer unsaturated carboxylic acid (FTUCA), 5:3 FTCA, and short-chain perfluoroalkyl carboxylates (PFCAs). Additional degradation products included 6:2 fluorotelomer sulfonamide (FTSAm), which was a major degradation product in the presence of either active or sterilized sludge, whereas 6:2 fluorotelomer sulfonate (FTSA) production was measured with sterilized sludge only. Six additional degradation products were tentatively identified by quadrupole time-of-flight mass spectrometry (qTOF-MS) and attributed to N-dealkylation and oxidation of 6:2 FTAA. Environ Toxicol Chem 2017;36:2012-2021. © 2017 SETAC. © 2017 SETAC.

  19. Effects of Aqueous Film-Forming Foams (AFFFs) on Trichloroethene (TCE) Dechlorination by a Dehalococcoides mccartyi-Containing Microbial Community.

    PubMed

    Harding-Marjanovic, Katie C; Yi, Shan; Weathers, Tess S; Sharp, Jonathan O; Sedlak, David L; Alvarez-Cohen, Lisa

    2016-04-05

    The application of aqueous film-forming foams (AFFFs) to extinguish chlorinated solvent-fueled fires has led to the co-contamination of poly- and perfluoroalkyl substances (PFASs) and trichloroethene (TCE) in groundwater and soil. Although reductive dechlorination of TCE by Dehalococcoides mccartyi is a frequently used remediation strategy, the effects of AFFF and PFASs on TCE dechlorination are not well-understood. Various AFFF formulations, PFASs, and ethylene glycols were amended to the growth medium of a D. mccartyi-containing enrichment culture to determine the impact on dechlorination, fermentation, and methanogenesis. The community was capable of fermenting organics (e.g., diethylene glycol butyl ether) in all AFFF formulations to hydrogen and acetate, but the product concentrations varied significantly according to formulation. TCE was dechlorinated in the presence of an AFFF formulation manufactured by 3M but was not dechlorinated in the presence of formulations from two other manufacturers. Experiments amended with AFFF-derived PFASs and perfluoroalkyl acids (PFAAs) indicated that dechlorination could be inhibited by PFASs but that the inhibition depends on surfactant concentration and structure. This study revealed that the fermentable components of AFFF can stimulate TCE dechlorination, while some of the fluorinated compounds in certain AFFF formulations can inhibit dechlorination.

  20. Experimental study on heat transfer performance of aluminium foam parallel-flow condenser in air conditioner

    NASA Astrophysics Data System (ADS)

    Zhang, X.; Wan, Z. M.; Chang, H. W.; Wang, Y. D.

    2017-01-01

    Open cell aluminium foam was used in parallel-flow condenser in air conditioner, and two condensers with different pore density were fabricated. The experimental study was conducted on the heat transfer performance and temperature distribution. The experimental results show that both of the heat transfer load and air pressure drop increase with the increase of pore density, air velocity is 2.5m/s, the heat transfer capacities of the condenser with 10PPI and 8PPI are 4.786kw and 3.344kW respectively. Along the flow direction of refrigerant, the outlet temperatures of refrigerant drop with the rise of air velocity when the inlet temperature is constant. The outlet temperature of the refrigerant decreases with the increase of pore density.

  1. Complete dechlorination of 2,4-dichlorophenol in aqueous solution on palladium/polymeric pyrrole-cetyl trimethyl ammonium bromide/foam-nickel composite electrode.

    PubMed

    Sun, Zhirong; Wei, Xuefeng; Han, Yanbo; Tong, Shan; Hu, Xiang

    2013-01-15

    The electrochemically reductive dechlorination of 2,4-dichlorophenol (2,4-DCP) in aqueous solution on palladium/polymeric pyrrole-cetyl trimethyl ammonium bromide/foam-nickel electrode (Pd/PPy-CTAB/foam-Ni electrode) was investigated in this paper. Pd/PPy-CTAB/foam-Ni electrode was prepared and characterized by cyclic voltammetry (CV), scanning electron microscope (SEM), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) adsorption and inductively coupled plasma-atomic emission spectroscopy (ICP-AES). The influences of some experimental factors such as the dechlorination current, dechlorination time and the initial pH on the removal efficiency and the current efficiency of 2,4-DCP dechlorination on Pd/PPy-CTAB/foam-Ni electrode were studied. Complete removal of 2,4-DCP was achieved and the current efficiency of 47.4% could be obtained under the conditions of the initial pH of 2.2, the dechlorination current of 5 mA and the dechlorination time of 50 min when the initial 2,4-DCP concentration was 100 mg L(-1). The analysis of high performance liquid chromatography (HPLC) identified that the intermediate products were 2-chlorophenol (2-CP) and 4-chlorophenol (4-CP). The final products were mainly phenol. Its further reduction product cyclohexanone was also detected. The electrocatalytic dechlorination pathways of 2,4-DCP on Pd/PPy-CTAB/foam-Ni electrode were discussed. The stability of the electrode was favorable that it could keep dechlorination efficiency at 100% after having been reused 10 times. Results revealed that the stable prepared Pd/PPy-CTAB/foam-Ni electrode presented a good application prospect in dechlorination process with high effectiveness and low cost. Copyright © 2012 Elsevier B.V. All rights reserved.

  2. Surfactant recovery from water using foam fractionation: Effect of temperature and added salt

    SciTech Connect

    Kumpabooth, K.; Osuwan, S.; Scamehorn, J.F.; Harwell, J.H.

    1999-01-01

    The purpose of this study was to investigate the use of foam fractionation to recover surfactant present at low concentrations in aqueous streams. A simple continuous mode foam fractionation was used, and three surfactants were chosen for this study: sodium dodecyl sulfate, cetylpyridinium chloride, and sodium n-hexadecyl diphenyloxide disulfonate. In a previous study the effects of surfactant concentration, air flow rate, liquid- and vapor-phase heights, and sparger type were investigated for these surfactants. Here, the effects of temperature and added salt are studied. It is found that the foam flow rate and enrichment ratio increase whereas the foam wetness and the rate of surfactant recovery decrease with increasing temperature. Increasing the concentration of added salt decreases the CMC of the surfactants. The foam flow rate, foam wetness, and the rate of surfactant recovery increase, while the enrichment ratio decreases with increasing concentration of salt.

  3. Additions to compact heat exchanger technology: Jet impingement cooling & flow & heat transfer in metal foam-fins

    NASA Astrophysics Data System (ADS)

    Onstad, Andrew J.

    Compact heat exchangers have been designed following the same basic methodology for over fifty years. However, with the present emphasis on energy efficiency and light weight of prime movers there is increasing demand for completely new heat exchangers. Moreover, new materials and mesoscale fabrication technologies offer the possibility of significantly improving heat exchanger performance over conventional designs. This work involves fundamental flow and heat transfer experimentation to explore two new heat exchange systems: in Part I, large arrays of impinging jets with local extraction and in Part II, metal foams used as fins. Jet impingement cooling is widely used in applications ranging from paper manufacturing to the cooling of gas turbine blades because of the very high local heat transfer coefficients that are possible. While the use of single jet impingement results in non-uniform cooling, increased and more uniform mean heat transfer coefficients may be attained by dividing the total cooling flow among an array of smaller jets. Unfortunately, when the spent fluid from the array's central jets interact with the outer jets, the overall mean heat transfer coefficient is reduced. This problem can be alleviated by locally extracting the spent fluid before it is able to interact with the surrounding jets. An experimental investigation was carried out on a compact impingement array (Xn/Djet = 2.34) utilizing local extraction of the spent fluid (Aspent/Ajet = 2.23) from the jet exit plane. Spatially resolved measurements of the mean velocity field within the array were carried out at jet Reynolds numbers of 2300 and 5300 by magnetic resonance velocimetry, MRV. The geometry provided for a smooth transition from the jet to the target surface and out through the extraction holes without obvious flow recirculation. Mean Nusselt number measurements were also carried out for a Reynolds number range of 2000 to 10,000. The Nusselt number was found to increase with the

  4. RAFT Dispersion Alternating Copolymerization of Styrene with N-Phenylmaleimide: Morphology Control and Application as an Aqueous Foam Stabilizer

    PubMed Central

    2016-01-01

    We report a new nonaqueous polymerization-induced self-assembly (PISA) formulation based on the reversible addition–fragmentation chain transfer (RAFT) dispersion alternating copolymerization of styrene with N-phenylmaleimide using a nonionic poly(N,N-dimethylacrylamide) stabilizer in a 50/50 w/w ethanol/methyl ethyl ketone (MEK) mixture. The MEK cosolvent is significantly less toxic than the 1,4-dioxane cosolvent reported previously [YangP.; Macromolecules2013, 46, 8545−8556]. The core-forming alternating copolymer block has a relatively high glass transition temperature (Tg), which leads to vesicular morphologies being observed during PISA, as well as the more typical sphere and worm phases. Each of these copolymer morphologies has been characterized by transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS) studies. TEM studies reveal micrometer-sized elliptical particles with internal structure, with SAXS analysis suggesting an oligolamellar vesicle morphology. This structure differs from that previously reported for a closely related PISA formulation utilizing a poly(methacrylic acid) stabilizer block for which unilamellar platelet-like particles are observed by TEM and SAXS. This suggests that interlamellar interactions are governed by the nature of the steric stabilizer layer. Moreover, using the MEK cosolvent also enables access to a unilamellar vesicular morphology, despite the high Tg of the alternating copolymer core-forming block. This was achieved by simply conducting the PISA synthesis at a higher temperature for a longer reaction time (80 °C for 24 h). Presumably, MEK solvates the core-forming block more than the previously utilized 1,4-dioxane cosolvent, which leads to greater chain mobility. Finally, preliminary experiments indicate that the worms are much more efficient stabilizers for aqueous foams than either the spheres or the oligolamellar elliptical vesicles. PMID:27708458

  5. 3D Graphene-Ni Foam as an Advanced Electrode for High-Performance Nonaqueous Redox Flow Batteries.

    PubMed

    Lee, Kyubin; Lee, Jungkuk; Kwon, Kyoung Woo; Park, Min-Sik; Hwang, Jin-Ha; Kim, Ki Jae

    2017-07-12

    Electrodes composed of multilayered graphene grown on a metal foam (GMF) were prepared by directly growing multilayer graphene sheets on a three-dimensional (3D) Ni-foam substrate via a self-catalyzing chemical vapor deposition process. The multilayer graphene sheets are successfully grown on the Ni-foam substrate surface, maintaining the unique 3D macroporous structure of the Ni foam. The potential use of GMF electrodes in nonaqueous redox flow batteries (RFBs) is carefully examined using [Co(bpy)3](+/2+) and [Fe(bpy)3](2+/3+) redox couples. The GMF electrodes display a much improved electrochemical activity and enhanced kinetics toward the [Co(bpy)3](+/2+) (anolyte) and [Fe(bpy)3](2+/3+) (catholyte) redox couples, compared with the bare Ni metal foam electrodes, suggesting that the 2D graphene sheets having lots of interdomain defects provide sufficient reaction sites and secure electric-conduction pathways. Consequently, a nonaqueous RFB cell assembled with GMF electrodes exhibits high Coulombic and voltage efficiencies of 87.2 and 90.9%, respectively, at the first cycle. This performance can be maintained up to the 50th cycle without significant efficiency loss. Moreover, the importance of a rational electrode design for improving electrochemical performance is addressed.

  6. Foam Microrheology

    SciTech Connect

    KRAYNIK,ANDREW M.; LOEWENBERG,MICHAEL; REINELT,DOUGLAS A.

    1999-09-01

    The microrheology of liquid foams is discussed for two different regimes: static equilibrium where the capillary number Ca is zero, and the viscous regime where viscosity and surface tension are important and Ca is finite. The Surface Evolver is used to calculate the equilibrium structure of wet Kelvin foams and dry soap froths with random structure, i.e., topological disorder. The distributions of polyhedra and faces are compared with the experimental data of Matzke. Simple shearing flow of a random foam under quasistatic conditions is also described. Viscous phenomena are explored in the context of uniform expansion of 2D and 3D foams at low Reynolds number. Boundary integral methods are used to calculate the influence of Ca on the evolution of foam microstructure, which includes bubble shape and the distribution of liquid between films, Plateau borders, and (in 3D) the nodes where Plateau borders meet. The micromechanical point of view guides the development of structure-property-processing relationships for foams.

  7. Attenuation of aqueous benzene in soils under saturated flow conditions.

    PubMed

    Kim, S-B; Kim, D-J; Yun, S-T

    2006-01-01

    The fate of aqueous benzene in subsurface was investigated in this study, focusing on the role of sorption and biodegradation on the benzene attenuation under dynamic flow conditions. Two sets of column tests were conducted in Plexiglass flow cells packed uniformly with sandy aquifer materials. The first set of the experiment was conducted with a step-type injection of benzene with different powder activated carbon (PAC) contents: (1) PAC = 0 %; (2) PAC = 0.5 %; (3) PAC = 2.0%. The second set was performed as a pulse-type with different test conditions: (4) benzene; (5) benzene and bacteria (Pseudomonas aeruginosa); (6) benzene and bacteria (P. aeruginosa) with hydrogen peroxide. In addition, numerical experiments were performed to examine the role of sorption processes on the benzene attenuation. In the step mode experiments, the KCl breakthrough curves (BTCs) reached the input concentration while the benzene BTCs were considerably lower than those of KCl with slight retardation for all cases, indicating that both reversible/retardation and irreversible sorption occurred. The pulse type tests showed that attenuation of benzene increased in the presence of bacteria due to biodegradation. The benzene attenuation by microbial degradation increased furthermore in the presence of hydrogen peroxide owing to sufficient supply of dissolved oxygen in soil column. Numerical experiments demonstrated that retardation could not contribute to the attenuation of benzene in soils but could only extend its breakthrough time. Experimental results indicated that aqueous benzene could be attenuated by irreversible sorption and biodegradation during transport through the subsurface. Additionally, the attenuation of aqueous benzene is closely related to organic carbon content and oxygen level existing in contaminated aquifers.

  8. Discrete Particle Model for Porous Media Flow using OpenFOAM at Intel Xeon Phi Coprocessors

    NASA Astrophysics Data System (ADS)

    Shang, Zhi; Nandakumar, Krishnaswamy; Liu, Honggao; Tyagi, Mayank; Lupo, James A.; Thompson, Karten

    2015-11-01

    The discrete particle model (DPM) in OpenFOAM was used to study the turbulent solid particle suspension flows through the porous media of a natural dual-permeability rock. The 2D and 3D pore geometries of the porous media were generated by sphere packing with the radius ratio of 3. The porosity is about 38% same as the natural dual-permeability rock. In the 2D case, the mesh cells reach 5 million with 1 million solid particles and in the 3D case, the mesh cells are above 10 million with 5 million solid particles. The solid particles are distributed by Gaussian distribution from 20 μm to 180 μm with expectation as 100 μm. Through the numerical simulations, not only was the HPC studied using Intel Xeon Phi Coprocessors but also the flow behaviors of large scale solid suspension flows in porous media were studied. The authors would like to thank the support by IPCC@LSU-Intel Parallel Computing Center (LSU # Y1SY1-1) and the HPC resources at Louisiana State University (http://www.hpc.lsu.edu).

  9. Foam drainage

    SciTech Connect

    Kraynik, A.M.

    1983-11-01

    Transient drainage from a column of persistent foam has been analyzed theoretically. Gravity-driven flow was assumed to occur through an interconnected network of Plateau borders that define the edges of foam cells taken to be regular pentagonal dodecahedrons. A small liquid volume fraction and monodisperse cell size distribution were assumed. In the basic model, it is assumed that all liquid is contained in Plateau borders that are bounded by rigid gas-liquid interfaces. The predicted half life, the time required for one half of the liquid to drain from the foam, is inversely proportional to the square of the cell diameter, illustrating the importance of foam structure in drainage. Liquid hold up in the films separating adjacent cells, nonuniform initial liquid volume fraction distribution and interfacial mobility are explored. Border suction due to reduced pressure in the Plateau borders provides a mechanism for film drainage. Simultaneous film drainage and flow through the Plateau borders are analyzed. Sufficient conditions for neglecting film drainage kinetics are obtained. The results indicate that improved foam stability is related to small cells, liquid hold up in the films and slow film drainage kinetics.

  10. Loop flow analysis of dissolved reactive phosphorus in aqueous samples.

    PubMed

    Ma, Jian; Li, Quanlong; Yuan, Dongxing

    2014-06-01

    The current flow based method for the determination of dissolved reactive phosphorus (DRP) suffers interference from salinity (e.g. index refractive difference) and the incidentally formed bubbles, which can be a problem for optical detection. Here we reported a simple and robust loop flow analysis (LFA) method for accurate measurement of DRP in different aqueous samples. The chemistry is based on the classic phosphomolybdenum blue (PMB) reaction and the PMB formed in a novel cross-shaped flow cell was detected at 700 nm using a miniature spectrophotometer. The effects of reagents on the kinetic formation of PMB were evaluated. The detection limit was 32 nM with an optical pathlength of 1cm and the relative standard deviations for repetitive determinations of 1, 2 and 8 µM phosphate solutions were 1.8% (n=113, without any stoppage during repeating analysis for >7h), 1.0% (n=49) and 0.39% (n=9), respectively. The analysis time was 4 min sample(-1). The effects of salinity and interfering ions (silicate and arsenate) were evaluated and showed no interference under the proposed protocol for DRP analysis. Using the LFA method, different aqueous samples with a salinity range of 0-34 were analyzed and the results showed excellent agreement with the reference method (slope 0.9982±0.0063, R(2)=0.9987, n=34). Recoveries for spiked samples varied from 95.4% to 103.7%. The proposed method showed insignificant interference from salinity, silicate and arsenate, higher reproducibility, easier operation and was free of the bubble problem.

  11. Oil repartition in a foam film architecture.

    PubMed

    Piroird, Keyvan; Lorenceau, Elise; Biance, Anne-Laure

    2014-09-28

    The propagation and distribution of oil inside the aqueous network of a foam is investigated in the case where oil can invade the foam without breaking it. The oil is injected into an elementary foam architecture of nine foam films and four vertices obtained by plunging a cubic frame in a foaming solution. The frame is then deformed to trigger a film switching (topological rearrangement named T1) and oil redistribution through this process is reported. Depending on the relative ratio of injected oil and water, different behaviours are observed. For small amounts of oil, a globule is trapped in one single node whereas for large oil volumes, it invades the four nodes of the foam film assembly. In both these cases, a T1 process does not change the oil distribution. However, for intermediate volumes, oil initially trapped in one node is able to propagate to the neighbouring nodes after the T1 process. This important observation shows that topological rearrangements, which naturally occur in foams when they evolve with time or when they flow, do affect the distribution of the third phase that they carry. These different regimes are captured by simple modeling based on the capillary pressure balance inside the foam network. Moreover, in the large-oil-volume limit, a transient situation is evidenced where an oil film is trapped within the freshly formed water film. This oil film modifies the dynamics of the T1 process and can be stable for up to a few minutes. We expect this mechanism to have consequences on the rheological properties of oil-laden foams. Film rupture dynamics is also experimentally captured.

  12. Resin Flow Behavior Simulation of Grooved Foam Sandwich Composites with the Vacuum Assisted Resin Infusion (VARI) Molding Process

    PubMed Central

    Zhao, Chenhui; Zhang, Guangcheng; Wu, Yibo

    2012-01-01

    The resin flow behavior in the vacuum assisted resin infusion molding process (VARI) of foam sandwich composites was studied by both visualization flow experiments and computer simulation. Both experimental and simulation results show that: the distribution medium (DM) leads to a shorter molding filling time in grooved foam sandwich composites via the VARI process, and the mold filling time is linearly reduced with the increase of the ratio of DM/Preform. Patterns of the resin sources have a significant influence on the resin filling time. The filling time of center source is shorter than that of edge pattern. Point pattern results in longer filling time than of linear source. Short edge/center patterns need a longer time to fill the mould compared with Long edge/center sources.

  13. Simple shearing flow of dry soap foams with TCP structure[Tetrahedrally Close-Packed

    SciTech Connect

    REINELT,DOUGLAS A.; KRAYNIK,ANDREW M.

    2000-02-16

    The microrheology of dry soap foams subjected to large, quasistatic, simple shearing deformations is analyzed. Two different monodisperse foams with tetrahedrally close-packed (TCP) structure are examined: Weaire-Phelan (A15) and Friauf-Laves (C15). The elastic-plastic response is evaluated by calculating foam structures that minimize total surface area at each value of strain. The minimal surfaces are computed with the Surface Evolver program developed by Brakke. The foam geometry and macroscopic stress are piecewise continuous functions of strain. The stress scales as T/V{sup 1/3} where T is surface tension and V is cell volume. Each discontinuity corresponds to large changes in foam geometry and topology that restore equilibrium to unstable configurations that violate Plateau's laws. The instabilities occur when the length of an edge on a polyhedral foam cell vanishes. The length can tend to zero smoothly or abruptly with strain. The abrupt case occurs when a small increase in strain changes the energy profile in the neighborhood of a foam structure from a local minimum to a saddle point, which can lead to symmetry-breaking bifurcations. In general, the new foam topology associated with each stable solution branch results from a cascade of local topology changes called T1 transitions. Each T1 cascade produces different cell neighbors, reduces surface energy, and provides an irreversible, film-level mechanism for plastic yield behavior. Stress-strain curves and average stresses are evaluated by examining foam orientations that admit strain-periodic behavior. For some orientations, the deformation cycle includes Kelvin cells instead of the original TCP structure; but the foam does not remain perfectly ordered. Bifurcations during subsequent T1 cascades lead to disorder and can even cause strain localization.

  14. Foam Micromechanics

    SciTech Connect

    Kraynik, A.M.; Neilsen, M.K.; Reinelt, D.A.; Warren, W.E.

    1998-11-03

    Foam evokes many different images: waves breaking at the seashore, the head on a pint of Guinness, an elegant dessert, shaving, the comfortable cushion on which you may be seated... From the mundane to the high tech, foams, emulsions, and cellular solids encompass a broad range of materials and applications. Soap suds, mayonnaise, and foamed polymers provide practical motivation and only hint at the variety of materials at issue. Typical of mukiphase materiaIs, the rheoIogy or mechanical behavior of foams is more complicated than that of the constituent phases alone, which may be gas, liquid, or solid. For example, a soap froth exhibits a static shear modulus-a hallmark of an elastic solid-even though it is composed primarily of two Newtonian fluids (water and air), which have no shear modulus. This apparent paradox is easily resolved. Soap froth contains a small amount of surfactant that stabilizes the delicate network of thin liq- uid films against rupture. The soap-film network deforms in response to a macroscopic strain; this increases interracial area and the corresponding sur- face energy, and provides the strain energy of classical elasticity theory [1]. This physical mechanism is easily imagined but very challenging to quantify for a realistic three-dimensional soap froth in view of its complex geome- try. Foam micromechanics addresses the connection between constituent properties, cell-level structure, and macroscopic mechanical behavior. This article is a survey of micromechanics applied to gas-liquid foams, liquid-liquid emulsions, and cellular solids. We will focus on static response where the foam deformation is very slow and rate-dependent phenomena such as viscous flow can be neglected. This includes nonlinear elasticity when deformations are large but reversible. We will also discuss elastic- plastic behavior, which involves yield phenomena. Foam structures based on polyhedra packed to fill space provide a unify- ing geometrical theme. Because a two

  15. Interlaboratory comparison of four heat flow meter apparatuses on planed polyisocyanurate boards foamed with CFC-11

    SciTech Connect

    Graves, R.S.; McElroy, D.L. ); Miller, R.G. Research Corp., St. Petersburg, FL ); Yarbrough, D.W. ); Zarr, R.R. )

    1991-06-01

    This report describes an interlaboratory comparison of apparent thermal conductivity (k) results on planed polyisocyanurate (PIR) boards foamed with chlorofluorocarbon-11 (CFC-11). Sequential tests were conducted at 75{degrees}F (24{degrees}C) at four facilities on two rigid (PIR) boards, individually and as a pair, using four comparative heat flow meter apparatuses. The specimens were shipped from lab to lab, and testing yielded 15 k-values that have two standard deviation (2 {alpha}) value of 2.2% when described by: k(Btu{center dot}in./h{center dot}ft{sup 2}{center dot}F) = 0/1365 + 1.15 {times} 10{sup {minus}4} t k(W/m{center dot}K) = 0.0197 + 1.66 {times} 10{sup {minus}5} t, where t is the elapsed time in days after planing of the boards. An increased 2 {sigma} value for board 2 may be associated with a larger variation in thickness. The 15 thermal conductance (C) values have a 2 {sigma} value of 3.2% when described by: C(Btu/H{center dot}h{center dot}{sup 2}{center dot}{degrees}F) = 0.1069 + 1.20 {times} 10{sup {minus}4} t. Thus, the 2 {sigma} (k-values) of the interlaboratory comparison is not reduced by comparing C values. 5 refs., 1 fig., 8 tabs.

  16. Effect of mesocelluar carbon foam electrode material on performance of vanadium redox flow battery

    NASA Astrophysics Data System (ADS)

    Jeong, Sanghyun; An, Sunhyung; Jeong, Jooyoung; Lee, Jinwoo; Kwon, Yongchai

    2015-03-01

    Languid reaction rate of VO2+/VO2+ redox couple is a problem to solve for improving performance of vanadium redox flow battery (VRFB). To facilitate the slow reaction materials including large pore sized mesocellular carbon foam (MSU-F-C and Pt/MSU-F-C) are used as new catalyst. Their catalytic activity and reaction reversibility are estimated and compared with other catalysts, while cycle tests of charge-discharge and polarization curve tests are implemented to evaluate energy efficiency (EE) and maximum power density (MPD). Their crystal structure, specific surface area and catalyst morphology are measured by XRD, BET and TEM. The new catalysts indicate high peak current ratio, small peak potential difference and high electron transfer rate constant, proving that their catalytic activity and reaction reversibility are superior. Regarding the charge-discharge and polarization curve tests, the VRFB single cells including new catalysts show high EE as well as low overpotential and internal resistance and high MPD. Such excellent results are due to mostly unique characteristics of MSU-F-C having large interconnected mesopores, high surface area and large contents of hydroxyl groups that serve as active sites for VO2+/VO2+ redox reaction and platinums (Pts) supporting the MSU-F-C. Indeed, employment of the catalysts including MSU-F-C leads to enhancement in performance of VRFB by facilitating the slow VO2+/VO2+ redox reaction.

  17. A metal-free organic-inorganic aqueous flow battery

    SciTech Connect

    Huskinson, B; Marshak, MP; Suh, C; Er, S; Gerhardt, MR; Galvin, CJ; Chen, XD; Aspuru-Guzik, A; Gordon, RG; Aziz, MJ

    2014-01-08

    As the fraction of electricity generation from intermittent renewable sources-such as solar or wind-grows, the ability to store large amounts of electrical energy is of increasing importance. Solid-electrode batteries maintain discharge at peak power for far too short a time to fully regulate wind or solar power output(1,2). In contrast, flow batteries can independently scale the power (electrode area) and energy (arbitrarily large storage volume) components of the system by maintaining all of the electro-active species in fluid form(3-5). Wide-scale utilization of flow batteries is, however, limited by the abundance and cost of these materials, particularly those using redox-active metals and precious-metal electrocatalysts(6,7). Here we describe a class of energy storage materials that exploits the favourable chemical and electro-chemical properties of a family of molecules known as quinones. The example we demonstrate is ametal-free flow battery based on the redox chemistry of 9,10-anthraquinone-2,7-disulphonic acid (AQDS). AQDS undergoes extremely rapid and reversible two-electron two-proton reduction on a glassy carbon electrode in sulphuric acid. An aqueous flow battery with inexpensive carbon electrodes, combining the quinone/hydroquinone couple with the Br-2/Br- redox couple, yields a peak galvanic power density exceeding 0.6 W cm(-2) at 1.3 A cm(-2). Cycling of this quinone-bromide flow battery showed >99 per cent storage capacity retention per cycle. The organic anthraquinone species can be synthesized from inexpensive commodity chemicals(8). This organic approach permits tuning of important properties such as the reduction potential and solubility by adding functional groups: for example, we demonstrate that the addition of two hydroxy groups to AQDS increases the open circuit potential of the cell by 11% and we describe a pathway for further increases in cell voltage. The use of p-aromatic redox-active organic molecules instead of redox-active metals

  18. A metal-free organic-inorganic aqueous flow battery.

    PubMed

    Huskinson, Brian; Marshak, Michael P; Suh, Changwon; Er, Süleyman; Gerhardt, Michael R; Galvin, Cooper J; Chen, Xudong; Aspuru-Guzik, Alán; Gordon, Roy G; Aziz, Michael J

    2014-01-09

    As the fraction of electricity generation from intermittent renewable sources--such as solar or wind--grows, the ability to store large amounts of electrical energy is of increasing importance. Solid-electrode batteries maintain discharge at peak power for far too short a time to fully regulate wind or solar power output. In contrast, flow batteries can independently scale the power (electrode area) and energy (arbitrarily large storage volume) components of the system by maintaining all of the electro-active species in fluid form. Wide-scale utilization of flow batteries is, however, limited by the abundance and cost of these materials, particularly those using redox-active metals and precious-metal electrocatalysts. Here we describe a class of energy storage materials that exploits the favourable chemical and electrochemical properties of a family of molecules known as quinones. The example we demonstrate is a metal-free flow battery based on the redox chemistry of 9,10-anthraquinone-2,7-disulphonic acid (AQDS). AQDS undergoes extremely rapid and reversible two-electron two-proton reduction on a glassy carbon electrode in sulphuric acid. An aqueous flow battery with inexpensive carbon electrodes, combining the quinone/hydroquinone couple with the Br2/Br(-) redox couple, yields a peak galvanic power density exceeding 0.6 W cm(-2) at 1.3 A cm(-2). Cycling of this quinone-bromide flow battery showed >99 per cent storage capacity retention per cycle. The organic anthraquinone species can be synthesized from inexpensive commodity chemicals. This organic approach permits tuning of important properties such as the reduction potential and solubility by adding functional groups: for example, we demonstrate that the addition of two hydroxy groups to AQDS increases the open circuit potential of the cell by 11% and we describe a pathway for further increases in cell voltage. The use of π-aromatic redox-active organic molecules instead of redox-active metals

  19. A metal-free organic-inorganic aqueous flow battery

    NASA Astrophysics Data System (ADS)

    Huskinson, Brian; Marshak, Michael P.; Suh, Changwon; Er, Süleyman; Gerhardt, Michael R.; Galvin, Cooper J.; Chen, Xudong; Aspuru-Guzik, Alán; Gordon, Roy G.; Aziz, Michael J.

    2014-01-01

    As the fraction of electricity generation from intermittent renewable sources--such as solar or wind--grows, the ability to store large amounts of electrical energy is of increasing importance. Solid-electrode batteries maintain discharge at peak power for far too short a time to fully regulate wind or solar power output. In contrast, flow batteries can independently scale the power (electrode area) and energy (arbitrarily large storage volume) components of the system by maintaining all of the electro-active species in fluid form. Wide-scale utilization of flow batteries is, however, limited by the abundance and cost of these materials, particularly those using redox-active metals and precious-metal electrocatalysts. Here we describe a class of energy storage materials that exploits the favourable chemical and electrochemical properties of a family of molecules known as quinones. The example we demonstrate is a metal-free flow battery based on the redox chemistry of 9,10-anthraquinone-2,7-disulphonic acid (AQDS). AQDS undergoes extremely rapid and reversible two-electron two-proton reduction on a glassy carbon electrode in sulphuric acid. An aqueous flow battery with inexpensive carbon electrodes, combining the quinone/hydroquinone couple with the Br2/Br- redox couple, yields a peak galvanic power density exceeding 0.6Wcm-2 at 1.3Acm-2. Cycling of this quinone-bromide flow battery showed >99 per cent storage capacity retention per cycle. The organic anthraquinone species can be synthesized from inexpensive commodity chemicals. This organic approach permits tuning of important properties such as the reduction potential and solubility by adding functional groups: for example, we demonstrate that the addition of two hydroxy groups to AQDS increases the open circuit potential of the cell by 11% and we describe a pathway for further increases in cell voltage. The use of π-aromatic redox-active organic molecules instead of redox-active metals represents a new and

  20. Foam process models.

    SciTech Connect

    Moffat, Harry K.; Noble, David R.; Baer, Thomas A.; Adolf, Douglas Brian; Rao, Rekha Ranjana; Mondy, Lisa Ann

    2008-09-01

    In this report, we summarize our work on developing a production level foam processing computational model suitable for predicting the self-expansion of foam in complex geometries. The model is based on a finite element representation of the equations of motion, with the movement of the free surface represented using the level set method, and has been implemented in SIERRA/ARIA. An empirically based time- and temperature-dependent density model is used to encapsulate the complex physics of foam nucleation and growth in a numerically tractable model. The change in density with time is at the heart of the foam self-expansion as it creates the motion of the foam. This continuum-level model uses an homogenized description of foam, which does not include the gas explicitly. Results from the model are compared to temperature-instrumented flow visualization experiments giving the location of the foam front as a function of time for our EFAR model system.

  1. The effect of melatonin on aqueous humor flow in humans during the day.

    PubMed

    Viggiano, S R; Koskela, T K; Klee, G G; Samples, J R; Arnce, R; Brubaker, R F

    1994-02-01

    Aqueous humor flow through the anterior chamber of the eye undergoes a circadian cycle. The rate of flow during the day is twice as high as the rate of flow at night. The pineal hormone, melatonin, also undergoes a circadian cycle. Melatonin levels are high at night, whereas aqueous humor flow is low. The authors studied the effect of oral melatonin on aqueous humor flow in humans. The effect of melatonin on aqueous humor flow was evaluated in 19 healthy human volunteers in a randomized, masked crossover study with a placebo control. The hormone or placebo was administered orally during the day when endogenous levels of melatonin are low. Aqueous flow was measured by fluorophotometry for 8 hours. The mean rate of flow during melatonin treatment was 2.71 +/- 0.64 microliters/minute (+/- standard deviation). The rate of flow during placebo treatment was 2.80 +/- 0.66 microliters/minute. There is no statistically significant difference between these two rates (P = 0.4). With a sample size of 19, the study has a power of 92% to detect at least a 15% difference in the rate of flow under the two conditions. Measurement of plasma concentration of melatonin in five subjects confirmed that concentrations after oral dosage reached peaks comparable with the normal endogenous nocturnal peaks. The authors conclude that melatonin concentrations during the day, comparable with plasma concentrations that occur spontaneously during sleep, do not suppress aqueous humor formation. The authors find no support for the idea that plasma melatonin, per se, can suppress aqueous formation or that the circadian rhythm of plasma melatonin is primarily responsible for the circadian rhythm of aqueous humor flow.

  2. Reduction of 5in./54 Gun Blast Overpressure by Means of an Aqueous Foam- Filled Muzzle Device

    DTIC Science & Technology

    1981-08-01

    W. Shea S. PERFORMING ORGANIZATION NAME AND ADDRESS 10. PROGRAM ELEMENT. PROJECT, TASK Naval Surface Weapons Center AREA & WORK UNIT NUMUERS Code N43...more than 15 dB was attained. Containment of the foam in a muzzle-mounted canister was investigated. This report addresses related areas of gun...the internal pressure distribucion could be established and in- formation could be provided about the strength requirement of the device. Pres- sure

  3. SediFoam: A general-purpose, open-source CFD-DEM solver for particle-laden flow with emphasis on sediment transport

    NASA Astrophysics Data System (ADS)

    Sun, Rui; Xiao, Heng

    2016-04-01

    With the growth of available computational resource, CFD-DEM (computational fluid dynamics-discrete element method) becomes an increasingly promising and feasible approach for the study of sediment transport. Several existing CFD-DEM solvers are applied in chemical engineering and mining industry. However, a robust CFD-DEM solver for the simulation of sediment transport is still desirable. In this work, the development of a three-dimensional, massively parallel, and open-source CFD-DEM solver SediFoam is detailed. This solver is built based on open-source solvers OpenFOAM and LAMMPS. OpenFOAM is a CFD toolbox that can perform three-dimensional fluid flow simulations on unstructured meshes; LAMMPS is a massively parallel DEM solver for molecular dynamics. Several validation tests of SediFoam are performed using cases of a wide range of complexities. The results obtained in the present simulations are consistent with those in the literature, which demonstrates the capability of SediFoam for sediment transport applications. In addition to the validation test, the parallel efficiency of SediFoam is studied to test the performance of the code for large-scale and complex simulations. The parallel efficiency tests show that the scalability of SediFoam is satisfactory in the simulations using up to O(107) particles.

  4. Lamella Division in a Foam Flowing through a Two-Dimensional Porous Medium: A Model Fragmentation Process

    NASA Astrophysics Data System (ADS)

    Géraud, Baudouin; Méheust, Yves; Cantat, Isabelle; Dollet, Benjamin

    2017-03-01

    We flow a 2D foam through a model 2D porous medium and study experimentally and numerically how the bubble size distribution evolves along the medium. The dominant mechanism of bubble creation is a fragmentation process occurring when bubbles pinched against obstacles are split in two smaller bubbles. We infer the statistics of these individual and local fragmentation events from the experimental data and propose a fragmentation equation to relate that statistics to the evolution of the global size distribution. The predicted evolution shows very good agreement with direct experimental measurements of the bubble size distribution.

  5. Surfactant monitoring by foam generation

    DOEpatents

    Mullen, Ken I.

    1997-01-01

    A device for monitoring the presence or absence of active surfactant or other surface active agents in a solution or flowing stream based on the formation of foam or bubbles is presented. The device detects the formation of foam with a light beam or conductivity measurement. The height or density of the foam can be correlated to the concentration of the active surfactant present.

  6. Foam Cushioning

    NASA Technical Reports Server (NTRS)

    1988-01-01

    One innovation developed by a contractor at Ames Research Center was an open cell polymeric foam material with unusual properties. Intended as padding for aircraft seats the material offered better impact protection against accidents, and also enhanced passenger comfort because it distributed body weight evenly over the entire contact area. Called a slow springback foam, it flows to match the contour of the body pressing against it, and returns to its original shape once the pressure is removed. It has many applications including aircraft cushions and padding, dental stools, and athletic equipment. Now it's used by Dynamic Systems, Inc. for medical applications such as wheel chairs for severely disabled people which allow them to sit for 3-8 hours where they used to be uncomfortable in 15-30 minutes.

  7. Modeling of polymer electrolyte membrane fuel cell with metal foam in the flow-field of the bipolar/end plates

    NASA Astrophysics Data System (ADS)

    Kumar, Atul; Reddy, R. G.

    A unified, three-dimensional, steady-state numerical mass-transfer single cell model for polymer electrolyte membrane fuel cell (PEMFC) was developed. The modeled fuel cell uses metal foam in the flow-field of the bipolar/end plates instead of the conventionally used rectangular channels. Transport equations formulated under the PEMFC conditions were solved using the commercial computational fluid dynamics software Fluent ® 6.0 with Gambit ® 2.0 as pre-processor. Simulations were performed for different permeability levels of the metal foam in the flow-field. Results showed a significant effect of permeability of the metal foam on the performance of the fuel cell. For example: at 10 -6 m 2 permeability of metal foam the value of average current density was 5943 A/m 2 while at 10 -11 m 2 permeability, the average current density was 8325 A/m 2. The average current density value for the multi-parallel flow-field channel design (channel width=0.0625 in., channel depth=0.0625 in. and land width=0.0625 in.), which corresponded to an equivalent permeability value of 4.4×10 -8 m 2 was 7019 A/m 2. This value for the porous configuration with same permeability and under similar conditions of temperature, pressure and reactants flow rate was slightly lower at 6794 A/m 2. The trend indicated that decreasing the permeability of the flow-field results in better performance from the cell. However, the permeability of the channel design can not be decreased below the value of around 10 -8 m 2, due to difficulty in machining thinner channels. Consequently, the use of metal foam flow-field is proposed in the bipolar/end plate. The developed model offers fuel cell developers a scope for improvement of the bipolar/end plates in the fuel cell, by switching over to the metal foam flow-field concept.

  8. Foam Dispenser

    NASA Technical Reports Server (NTRS)

    1985-01-01

    William G. Simpson, a NASA/Marshall employee, invented and patented a foam mixing dispensing device. He is supplying his Simpson mixer to a number of foam applications where it is used to apply foam for insulation purposes.

  9. Numerical study of metal foam heat sinks under uniform impinging flow

    NASA Astrophysics Data System (ADS)

    Andreozzi, A.; Bianco, N.; Iasiello, M.; Naso, V.

    2017-01-01

    The ever-increasing demand for performance improvement and miniaturization of electronics has led to a significant generation of waste heat that must be dissipated to ensure a reliable device operation. The miniaturization of the components complicates this task. In fact, reducing the heat transfer area, at the same required heat rate, it is necessary to increase the heat flux, so that the materials operate in a temperature range suitable to its proper functioning. Traditional heat sinks are no longer capable of dissipating the generated heat and innovative approaches are needed to address the emerging thermal management challenges. Recently, heat transfer in open-cell metal foams under an impinging jet has received attention due to the considerable heat transfer potential of combining two cooling technologies: impinging jet and porous medium. This paper presents a numerical study on Finned Metal Foam (FMF) and Metal Foam (MF) heat sinks under impinging air jet cooling. The analysis is carried out by means of the commercial software COMSOL Multiphysics®. The purpose is to analyze the thermal performance of the metal foam heat sink, finned or not, varying its geometric parameters. Results are presented in terms of predicted dissipated heat rate, convective heat transfer coefficient and pressure losses.

  10. Foams for barriers and nonlethal weapons

    NASA Astrophysics Data System (ADS)

    Rand, Peter B.

    1997-01-01

    Our times demand better solutions to conflict resolution than simply shooting someone. Because of this, police and military interest in non-lethal concepts is high. Already in use are pepper sprays, bean-bag guns, flash-bang grenades, and rubber bullets. At Sandia we got a head start on non- lethal weapon concepts. Protection of nuclear materials required systems that went way beyond the traditional back vault. Dispensable deterrents were used to allow a graduated response to a threat. Sticky foams and stabilized aqueous foams were developed to provide access delay. Foams won out for security systems simply because you could get a large volume from a small container. For polymeric foams the expansion ratio is thirty to fifty to one. In aqueous foams expansion ratios of one thousand to ne are easily obtained. Recent development work on sticky foams has included a changeover to environmentally friendly solvents, foams with very low toxicity, and the development of non-flammable silicone resin based foams. High expansion aqueous foams are useful visual and aural obscurants. Our recent aqueous foam development has concentrated on using very low toxicity foaming agents combined with oleoresin capsicum irritant to provide a safe but highly irritating foam.

  11. Determining Aqueous Fullerene Particle Size Distributions by Asymmetric Flow Field-Flow Fractionation (AF4) without Surfactants

    EPA Science Inventory

    To determine the behavior of nanoparticles in environmental systems, methods must be developed to measure nanoparticle size. Asymmetric Flow Field Flow Fractionation (AF4) is an aqueous compatible size separation technique which is able to separate particles from 1 nm to 10 µm in...

  12. Determining Aqueous Fullerene Particle Size Distributions by Asymmetric Flow Field-Flow Fractionation (AF4) without Surfactants

    EPA Science Inventory

    To determine the behavior of nanoparticles in environmental systems, methods must be developed to measure nanoparticle size. Asymmetric Flow Field Flow Fractionation (AF4) is an aqueous compatible size separation technique which is able to separate particles from 1 nm to 10 µm in...

  13. interThermalPhaseChangeFoam-A framework for two-phase flow simulations with thermally driven phase change

    NASA Astrophysics Data System (ADS)

    Nabil, Mahdi; Rattner, Alexander S.

    The volume-of-fluid (VOF) approach is a mature technique for simulating two-phase flows. However, VOF simulation of phase-change heat transfer is still in its infancy. Multiple closure formulations have been proposed in the literature, each suited to different applications. While these have enabled significant research advances, few implementations are publicly available, actively maintained, or inter-operable. Here, a VOF solver is presented (interThermalPhaseChangeFoam), which incorporates an extensible framework for phase-change heat transfer modeling, enabling simulation of diverse phenomena in a single environment. The solver employs object oriented OpenFOAM library features, including Run-Time-Type-Identification to enable rapid implementation and run-time selection of phase change and surface tension force models. The solver is packaged with multiple phase change and surface tension closure models, adapted and refined from earlier studies. This code has previously been applied to study wavy film condensation, Taylor flow evaporation, nucleate boiling, and dropwise condensation. Tutorial cases are provided for simulation of horizontal film condensation, smooth and wavy falling film condensation, nucleate boiling, and bubble condensation. Validation and grid sensitivity studies, interfacial transport models, effects of spurious currents from surface tension models, effects of artificial heat transfer due to numerical factors, and parallel scaling performance are described in detail in the Supplemental Material (see Appendix A). By incorporating the framework and demonstration cases into a single environment, users can rapidly apply the solver to study phase-change processes of interest.

  14. Foam Experiment Hardware are Flown on Microgravity Rocket MAXUS 4

    NASA Astrophysics Data System (ADS)

    Lockowandt, C.; Löth, K.; Jansson, O.; Holm, P.; Lundin, M.; Schneider, H.; Larsson, B.

    2002-01-01

    The Foam module was developed by Swedish Space Corporation and was used for performing foam experiments on the sounding rocket MAXUS 4 launched from Esrange 29 April 2001. The development and launch of the module has been financed by ESA. Four different foam experiments were performed, two aqueous foams by Doctor Michele Adler from LPMDI, University of Marne la Vallée, Paris and two non aqueous foams by Doctor Bengt Kronberg from YKI, Institute for Surface Chemistry, Stockholm. The foam was generated in four separate foam systems and monitored in microgravity with CCD cameras. The purpose of the experiment was to generate and study the foam in microgravity. Due to loss of gravity there is no drainage in the foam and the reactions in the foam can be studied without drainage. Four solutions with various stabilities were investigated. The aqueous solutions contained water, SDS (Sodium Dodecyl Sulphate) and dodecanol. The organic solutions contained ethylene glycol a cationic surfactant, cetyl trimethyl ammonium bromide (CTAB) and decanol. Carbon dioxide was used to generate the aqueous foam and nitrogen was used to generate the organic foam. The experiment system comprised four complete independent systems with injection unit, experiment chamber and gas system. The main part in the experiment system is the experiment chamber where the foam is generated and monitored. The chamber inner dimensions are 50x50x50 mm and it has front and back wall made of glass. The front window is used for monitoring the foam and the back window is used for back illumination. The front glass has etched crosses on the inside as reference points. In the bottom of the cell is a glass frit and at the top is a gas in/outlet. The foam was generated by injecting the experiment liquid in a glass frit in the bottom of the experiment chamber. Simultaneously gas was blown through the glass frit and a small amount of foam was generated. This procedure was performed at 10 bar. Then the pressure was

  15. Foam flow and liquid films motion: role of the surfactants properties

    NASA Astrophysics Data System (ADS)

    Cantat, Isabelle

    2011-11-01

    Liquid foams absorb energy in a much more efficient way than each of its constituents, taken separately. However, the local process at the origin of the energy dissipation is not entirely elucidated yet, and several models may apply, thus making worth local studies on simpler systems. We investigate the motion through a wet tube of transverse soap films, or lamellae, combining local thickness and velocity measurements in the wetting film. For foaming solution with a high dilatational surface modulus, we reveal a zone of several centimeters in length, the dynamic wetting film, which is significantly influenced by a moving lamella. The dependence of this influence length on lamella velocity and wetting film thickness provides an accurate discrimination among several possible surfactants models. In collaboration with B. Dollet.

  16. Size-differentiated lateral migration of bubbles in Couette flow of two-dimensional foam

    NASA Astrophysics Data System (ADS)

    Mohammadigoushki, Hadi; Feng, James J.

    2012-11-01

    In this Talk, we report experiments on lateral migration of bubbles in a two-dimensional foam sheared in a narrow-gap Couette device. A larger bubble in an otherwise monodisperse bubble raft migrates toward the center of the gap as long as the bubble size ratio and the shear rate are each above a threshold. The migration speed is roughly two orders of magnitude higher than that of a single bubble, and increases with the shear rate and the size ratio. The bubble also deforms much more than an isolated one at the same shear rate. Modifying the Chan-Leal solution for the migration of a single submerged bubble or drop, we derive a formula that successfully predicts all the migration trajectories recorded in the experiment. The threshold for migration corresponds to the wall repulsion force overcoming the capillary force in the 2D foam. The size-differentiated bubble migration provides an explanation for previously observed size segregation in sheared 3D polydisperse foams.

  17. Size-Differentiated Lateral Migration of Bubbles in Couette Flow of Two-Dimensional Foam

    NASA Astrophysics Data System (ADS)

    Mohammadigoushki, Hadi; Feng, James J.

    2012-08-01

    We report experiments on lateral migration of bubbles in a two-dimensional foam sheared in a narrow-gap Couette device. A larger bubble in an otherwise monodisperse bubble raft migrates toward the center of the gap as long as the bubble size ratio and the shear rate are each above a threshold. The migration speed is roughly two orders of magnitude higher than that of a single bubble, and increases with the shear rate and the size ratio. The bubble also deforms much more than an isolated one at the same shear rate. Modifying the Chan-Leal solution for the migration of a single submerged bubble or drop, we derive a formula that successfully predicts all the migration trajectories recorded in the experiment. The threshold for migration corresponds to the wall repulsion force overcoming the capillary force in the two-dimensional foam. The size-differentiated bubble migration provides an explanation for previously observed size segregation in sheared three-dimensional polydisperse foams.

  18. Metal foam evolution studied by synchrotron radioscopy

    NASA Astrophysics Data System (ADS)

    Banhart, John; Stanzick, Heiko; Helfen, Lukas; Baumbach, Tilo

    2001-02-01

    High-intensity synchrotron x-ray radioscopy was used to obtain real-time images of foaming metals, thus allowing the formation, growth, and decay of such systems to be studied. Bubble generation, foam coalescence and drainage of an aluminum-based alloy foam were investigated. Although the foaming process appears to be very similar to the formation of aqueous foams, the observed rupture behavior of thin metal films suggests that the processes responsible for metal foam stabilization and destabilization must be quite different.

  19. Adding Complex Terrain and Stable Atmospheric Condition Capability to the OpenFOAM-based Flow Solver of the Simulator for On/Offshore Wind Farm Applications (SOWFA): Preprint

    SciTech Connect

    Churchfield, M. J.; Sang, L.; Moriarty, P. J.

    2013-09-01

    This paper describes changes made to NREL's OpenFOAM-based wind plant aerodynamics solver such that it can compute the stably stratified atmospheric boundary layer and flow over terrain. Background about the flow solver, the Simulator for Off/Onshore Wind Farm Applications (SOWFA) is given, followed by details of the stable stratification/complex terrain modifications to SOWFA, along with somepreliminary results calculations of a stable atmospheric boundary layer and flow over a simply set of hills.

  20. Structure design of and experimental research on a two-stage laval foam breaker for foam fluid recycling.

    PubMed

    Wang, Jin-song; Cao, Pin-lu; Yin, Kun

    2015-07-01

    Environmental, economical and efficient antifoaming technology is the basis for achievement of foam drilling fluid recycling. The present study designed a novel two-stage laval mechanical foam breaker that primarily uses vacuum generated by Coanda effect and Laval principle to break foam. Numerical simulation results showed that the value and distribution of negative pressure of two-stage laval foam breaker were larger than that of the normal foam breaker. Experimental results showed that foam-breaking efficiency of two-stage laval foam breaker was higher than that of normal foam breaker, when gas-to-liquid ratio and liquid flow rate changed. The foam-breaking efficiency of normal foam breaker decreased rapidly with increasing foam stability, whereas the two-stage laval foam breaker remained unchanged. Foam base fluid would be recycled using two-stage laval foam breaker, which would reduce the foam drilling cost sharply and waste disposals that adverse by affect the environment.

  1. RETINAL BLOOD FLOW CORRELATES TO AQUEOUS VASCULAR ENDOTHELIAL GROWTH FACTOR IN CENTRAL RETINAL VEIN OCCLUSION.

    PubMed

    Yamada, Yoshihisa; Suzuma, Kiyoshi; Matsumoto, Makiko; Tsuiki, Eiko; Fujikawa, Azusa; Harada, Takafumi; Kitaoka, Takashi

    2015-10-01

    As laser speckle flowgraphy can measure blood flow distribution in the ocular fundus, the authors analyzed the relationship between retinal blood flow and aqueous vascular endothelial growth factor (VEGF) concentration in central retinal vein occlusion. This prospective observational study examined 45 eyes of 45 patients with central retinal vein occlusion before treatment. Blood flow in large vessels around and at the optic disk, aqueous VEGF concentration, and arteriovenous passage time were examined. Blood flow was evaluated as mean blur rate by laser speckle flowgraphy. Fluorescein angiography found 20 ischemic and 25 nonischemic type eyes. Aqueous VEGF concentration in the ischemic type was significantly higher than that in the nonischemic type (P = 0.01). Arteriovenous passage time was significantly correlated to the logarithm of the aqueous VEGF concentration (P = 0.0001). Mean blur rate of the affected eye/mean blur rate of the unaffected eye of the ischemic type was significantly lower than the nonischemic type (P = 0.039). Additionally, mean blur rate was significantly correlated both to the logarithm of the aqueous VEGF concentration (P < 0.0001) and to the arteriovenous passage time (P = 0.0001). Laser speckle flowgraphy may be useful for predicting aqueous VEGF concentration and severity of central retinal vein occlusion.

  2. Pulsatile flow into the aqueous veins: Manifestations in normal and glaucomatous eyes

    PubMed Central

    Johnstone, Murray; Martin, Elizabeth; Jamil, Annisa

    2015-01-01

    The aqueous outflow system is unique because nowhere else can the pattern of flow of an extravascular fluid be directly observed as it returns to the vascular system. Such observations reveal that aqueous flow both from Schlemm’s canal into the aqueous veins and from the aqueous veins into the episcleral veins is pulsatile. Pulsatile aqueous flow mechanisms are observable in vivo not only in normal and but also in glaucomatous eyes. A series of specific patterns accompany the pulsatile mixing of aqueous with blood in the episcleral veins. These directly observable patterns of pulsatile flow are synchronous with intraocular pressure (IOP) transients induced by the cardiac pulse, blinking and eye movement. Patterns of pulsatile flow are altered by events that increase IOP such as pressure on the side of the eye, tonography and water drinking. Pulsatile flow stops when IOP is reduced below its resting level, but begins again when IOP returns to the resting level. Pulsatile flow reduction probably results from the intrinsic reduction of pulse amplitude at a lower IOP, and may thus provide a passive mechanism to maintain short-term homeostasis. Thus modulation of the pulsatile flow phenomenon appears to maintain a homeostatic IOP setpoint. Visible pulsatile flow abnormalities develop in glaucoma patients. Medications that reduce IOP through improvement in outflow do so through pulsatile flow mechanisms. Laboratory studies have demonstrated that cyclic stresses in outflow tissues alter signaling pathways, cytoskeletal responses, extracellular matrix composition and cytokine secretion. How physiologic pulse transients orchestrate cellular responses and how cellular responses identified in the laboratory may in turn regulate pulsatile aqueous outflow is unknown. Linkage of laboratory and in vivo observations await an improved understanding of how cellular and extracellular structures within the outflow system are able to generate an aqueous pulse wave. The purpose of the

  3. Diurnal variation in peak expiratory flow rate among workers exposed to toluene diisocyanate in the polyurethane foam manufacturing industry.

    PubMed

    Lee, H S; Phoon, W H

    1992-06-01

    The diurnal variation in peak expiratory flow rate (PEFR) was studied in 26 mixers from eight factories making polyurethane foam, who were exposed to toluene diisocyanate (TDI), and 26 unexposed controls matched for age, race, and smoking. They were all men. The mean diurnal variation in PEFR of the mixers was 6.2%, which was significantly higher than the 4.3% for controls. Six mixers had a diurnal variation of greater than 15% on at least one day compared with none among the controls. There was, however, no overt cause of occupational asthma. All but one of the 24 environmental samples taken exceeded the short term exposure limit of 0.02 ppm for TDI. This accounted for the high prevalence (50%) of irritative symptoms such as cough and eye irritation. Forced expiratory volume in one second (FEV1) and FEV1/forced vital capacity (FVC) (%) was negatively correlated with duration of exposure to TDI. Foam workers may still have high exposure to TDI, high prevalence of irritative symptoms, increased diurnal variation in PEFR and evidence of chronic airway obstruction, particularly in those with greater than or equal to 10 years of exposure.

  4. Convective Instabilities in Liquid Foams

    NASA Technical Reports Server (NTRS)

    Veretennikov, Igor; Glazier, James A.

    2004-01-01

    The main goal of this work is to better understand foam behavior both on the Earth and in microgravity conditions and to determine the relation between a foam's structure and wetness and its rheological properties. Our experiments focused on the effects of the bubble size distribution (BSD) on the foam behavior under gradual or stepwise in the liquid flow rate and on the onset of the convective instability. We were able to show experimentally, that the BSD affects foam rheology very strongly so any theory must take foam texture into account.

  5. Revaluation of stockpile amount of PFOS-containing aqueous film-forming foam in Japan: gaps and pitfalls in the stockpile survey.

    PubMed

    Zushi, Yasuyuki; Yamamoto, Atsushi; Tsunemi, Kiyotaka; Masunaga, Shigeki

    2017-03-01

    Stockpiles of perfluoro-octane sulfonic acid (PFOS) containing aqueous film-forming foam (AFFF) have the potential to be emitted by leaching, spills, and during use in fire response and other processes. Several studies have discussed the high levels of stockpiled PFOS-containing AFFF and the risk they pose to the environment; however, there are large gaps in the amounts in Japan compared with other countries. For example, 300 tons are stockpiled in Canada, 2200-2600 tons in Switzerland, 1400 tons in Norway, and 19,000 tons in Japan from their reports for publication. The gap is considered to be a result of lack of surveys of several important sources. In this study, we revaluated the stockpile of AFFF in Japan to verify the reported value and identify the source of this gap based on information available in peer-reviewed papers, governmental reports, and business reports. The major reason for the gap between Japan and other countries was considered to be the survey of stockpiles in car-parking facilities, which accounted for 46.7% of the total amounts in Japan, but were not considered in other countries. These stockpiles indicate a high potential for accidental leaching or spilling of the AFFF by careless storage. Therefore, it is recommended that continual surveys of the AFFF stockpile in car-parking facilities be conducted in the rest of the world.

  6. Biomonitoring of perfluorochemicals and toxicity to the downstream fish community of Etobicoke Creek following deployment of aqueous film-forming foam.

    PubMed

    Oakes, Ken D; Benskin, Jonathan P; Martin, Jonathan W; Ings, Jennifer S; Heinrichs, Jill Y; Dixon, D George; Servos, Mark R

    2010-06-10

    On August 2, 2005, Air France Flight 358 descended on Lester B. Pearson International Airport (Toronto, ON, Canada) during adverse weather conditions and overran the runway, leading to an onboard fire which destroyed the aircraft. Large quantities (48000L) of aqueous film-forming foam (AFFF) were applied to the burning fuselage within meters of Etobicoke Creek. Local authorities could not confirm the identity of the AFFF formulation applied, but chemical analyses of fish livers collected 9 days post-AFFF application indicated that no perfluorinated acids (PFAs) were elevated at the site of application or downstream. This, and higher concentrations of a fluorotelomer sulfonate in fish liver collected downstream, suggests that an AFFF containing telomerized polyfluorinated material was likely used. However, as an urbanized stream within a heavily developed commercial, industrial, and residential watershed, background levels of perfluorinated compounds in Etobicoke Creek were considerable at all sites. Enlarged fish livers adjacent the AFFF-application site, commensurate with depressed peroxisomal beta-oxidation and hepatic oxidative stress, demonstrate some short-term impact of the AFFF on exposed fish within 9 days of its release. Most fish biochemical responses had recovered to normal values by 120 days, although there was some indication that AFFF-associated contamination shifted further downstream over this interval. This study suggests contemporary AFFFs exert relatively low toxicity on fish communities under realistic exposure scenarios.

  7. Discovery of 40 Classes of Per- and Polyfluoroalkyl Substances in Historical Aqueous Film-Forming Foams (AFFFs) and AFFF-Impacted Groundwater.

    PubMed

    Barzen-Hanson, Krista A; Roberts, Simon C; Choyke, Sarah; Oetjen, Karl; McAlees, Alan; Riddell, Nicole; McCrindle, Robert; Ferguson, P Lee; Higgins, Christopher P; Field, Jennifer A

    2017-02-21

    Aqueous film-forming foams (AFFFs), containing per- and polyfluoroalkyl substances (PFASs), are released into the environment during response to fire-related emergencies. Repeated historical applications of AFFF at military sites were a result of fire-fighter training exercises and equipment testing. Recent data on AFFF-impacted groundwater indicates that ∼25% of the PFASs remain unidentified. In an attempt to close the mass balance, a systematic evaluation of 3M and fluorotelomer-based AFFFs, commercial products, and AFFF-impacted groundwaters from 15 U.S. military bases was conducted to identify the remaining PFASs. Liquid chromatography quadrupole time-of-flight mass spectrometry was used for compound discovery. Nontarget analysis utilized Kendrick mass defect plots and a "nontarget" R script. Suspect screening compared masses with those of previously reported PFASs. Forty classes of novel anionic, zwitterionic, and cationic PFASs were discovered, and an additional 17 previously reported classes were observed for the first time in AFFF and/or AFFF-impacted groundwater. All 57 classes received an acronym and IUPAC-like name derived from collective author knowledge. Thirty-four of the 40 newly identified PFAS classes derive from electrochemical fluorination (ECF) processes, most of which have the same base structure. Of the newly discovered PFASs found only in AFFF-impacted groundwater, 11 of the 13 classes are ECF-derived, and the remaining two classes are fluorotelomer-derived, which suggests that both ECF- and fluorotelomer-based PFASs are persistent in the environment.

  8. Mechanical Characterization of Rigid Polyurethane Foams

    SciTech Connect

    Lu, Wei-Yang

    2014-12-01

    Foam materials are used to protect sensitive components from impact loading. In order to predict and simulate the foam performance under various loading conditions, a validated foam model is needed and the mechanical properties of foams need to be characterized. Uniaxial compression and tension tests were conducted for different densities of foams under various temperatures and loading rates. Crush stress, tensile strength, and elastic modulus were obtained. A newly developed confined compression experiment provided data for investigating the foam flow direction. A biaxial tension experiment was also developed to explore the damage surface of a rigid polyurethane foam.

  9. Springback Foam

    NASA Technical Reports Server (NTRS)

    1979-01-01

    A decade ago, NASA's Ames Research Center developed a new foam material for protective padding of airplane seats. Now known as Temper Foam, the material has become one of the most widely-used spinoffs. Latest application is a line of Temper Foam cushioning produced by Edmont-Wilson, Coshocton, Ohio for office and medical furniture. The example pictured is the Classic Dental Stool, manufactured by Dentsply International, Inc., York, Pennsylvania, one of four models which use Edmont-Wilson Temper Foam. Temper Foam is an open-cell, flameresistant foam with unique qualities.

  10. The search for alternative aqueous film forming foams (AFFF) with a low environmental impact: physiological and transcriptomic effects of two Forafac(®) fluorosurfactants in turbot.

    PubMed

    Hagenaars, A; Meyer, I J; Herzke, D; Pardo, B G; Martinez, P; Pabon, M; De Coen, W; Knapen, D

    2011-08-01

    Fluorosurfactants are the key components in aqueous film forming foams (AFFF). They provide these fire fighting agents with the required low surface tension and they enable film formation on top of lighter fuels to prevent burn back. Development of effective and environmentally acceptable PFOS alternatives is one of the most important priorities in the fire fighting foam industry. DuPont™ offers the fluorosurfactant mixtures Forafac(®)1157 and Forafac(®)1157N for the formulation of AFFFs which are alternatives to the persistent and toxic perfluorooctane sulphonate (PFOS). Ecotoxicological testing of these inadequately documented mixtures is necessary to include them in AFFF hazard and risk assessment. Juvenile turbot (Scophthalmus maximus) were exposed for 14 days to 0.1; 0.5 and 1.5mg/L of the fluorosurfactant mixtures used in Forafac(®)1157 and Forafac(®)1157N. In an initial transcriptomics experiment, microarray analysis revealed differentially expressed transcripts of genes which were mainly involved in digestion and in the immune system. This discovery-driven screening approach offered the basis for new hypotheses that were tested in two subsequent experiments in which food intake, energy reserves, growth and a set of haematological parameters were examined. Additionally, effects of the two mixtures were compared to those of PFOS. Based on the results of this study, the mode of action of Forafac(®)1157N was the activation of the acute phase reaction resulting in increased leukocyte concentrations and the inhibition of growth due to the high energetic cost of toxicant exposure. For Forafac(®)1157, evidences of immunosuppression were found on the transcriptional level and the altered differential leukocyte profiles indicated that stress was induced in these fish. However, food intake, energy reserves and growth were not compromised, even at high exposure concentrations, which was in contrast to the effects seen after PFOS exposure. Taking into account

  11. Flow Boiling Heat Transfer to Lithium Bromide Aqueous Solution in Subcooled Region

    NASA Astrophysics Data System (ADS)

    Furukawa, Masahiro; Kaji, Masao; Nishizumi, Takeharu; Ozaki, Shinji; Sekoguchi, Kotohiko

    To improve the thermal performance of high temperature generator of absorption chiller/heater, heat transfer characteristics of flow boiling of lithium bromide aqueous solution in the subcooled region were experimentally investigated. Experiments were made for water and lithium bromide aqueous solution flowing in a rectangular channel (5 mm × 20 mm cross section) with one side wall heated. Boiling onset quality of lithium bromide aqueous solution is greater than that of water. The heat transfer coefficient of lithium bromide aqueous solution is about a half of that of water under the same experimental conditions of inlet velocity and heat flux. The experimental data of heat transfer coefficient for water are compared with the empirical correlation of Thom et al.11) and a fairly good agreement is obtained. The predictive calculations by the method of Sekoguchi et al.12) are compared with the data for water and lithium bromide aqueous solution. Agreement between them is good for water, while the results for lithium bromide aqueous solution are not satisfactory.

  12. Fluorophotometric determination of aqueous humor flow rates in red-tailed hawks (Buteo jamaicensis).

    PubMed

    Jones, Michael P; Ward, Daniel A

    2012-04-01

    To determine aqueous humor flow rate (AHFR) in an avian species by use of anterior segment fluorophotometry. 9 healthy red-tailed hawks (Buteo jamaicensis; 4 males and 5 females) that ranged from 8 months to 8 years of age. A protocol was developed for fluorophotometric determination of AHFR. Topical administration of 10% fluorescein was used to load the corneas, and corneal and aqueous humor fluorescein concentrations were measured approximately 5, 6.5, and 8 hours later. Concentration-versus-time plots were generated, and slopes and cornea-to-aqueous humor concentration ratios from these plots were used to manually calculate flow rates. Mean ± SD AHFRs for the right eye, left eye, and both eyes were 3.17 ± 1.36 μL/min (range, 1.67 to 6.21 μL/min), 2.86 ± 0.88 μL/min (range, 2.04 to 4.30 μL/min), and 2.90 ± 0.90 μL/min (range, 1.67 to 4.42 μL/min), respectively. The AHFRs were similar for right and left eyes. These flow rates represented a mean aqueous humor transfer coefficient of 0.0082/min, which is similar to that of mammalian species. The AHFR in red-tailed hawks was similar to that of most mammalian species, and the fractional egress was almost identical to that of other species. This information will allow a greater understanding of aqueous humor flow in avian eyes, which is crucial when evaluating diseases that affect avian eyes as well as medications that alter aqueous humor flow.

  13. Time scales for drainage and imbibition in gellified foams: application to decontamination processes.

    PubMed

    Deleurence, Rémi; Saison, Tamar; Lequeux, François; Monteux, Cécile

    2015-09-21

    We probe the drainage and imbibition dynamics of foams in which the continuous aqueous phase is a transient gel-like network. To produce these foams, we provide a new method - a PVA (polyvinyl alcohol) solution is first foamed and then a cross-linker, Borax, is added, which binds reversibly to the PVA chains. The resulting foams are ultra-stable-over a month. We find that the typical time for gravitational drainage of the continuous phase can be slowed down from hours to several weeks by tuning the Borax concentration. We show that the Borax concentration controls both the bulk viscosity of the continuous phase and the surface viscosity of the air-water interfaces. From these results we suggest that the PVA molecules adsorbed at the bubble interfaces are highly cross-linked by the Borax molecules. We find that the capillary rise of a dyed liquid into these foams is orders of magnitude faster than the drainage flow, meaning that these foams can quickly absorb liquids. These results show that these foams could be used to clean or decontaminate surfaces covered with liquid wastes. Indeed we show that the PVA-Borax foam can easily be spread on a surface, absorb a liquid without destabilizing and be dried afterward to recover the waste.

  14. Direct measurement of pressure-independent aqueous humour flow using iPerfusion.

    PubMed

    Madekurozwa, Michael; Reina-Torres, Ester; Overby, Darryl R; Sherwood, Joseph M

    2017-09-01

    Reduction of intraocular pressure is the sole therapeutic target for glaucoma. Intraocular pressure is determined by the dynamics of aqueous humour secretion and outflow, which comprise several pressure-dependent and pressure-independent mechanisms. Accurately quantifying the components of aqueous humour dynamics is essential in understanding the pathology of glaucoma and the development of new treatments. To better characterise aqueous humour dynamics, we propose a method to directly measure pressure-independent aqueous humour flow. Using the iPerfusion system, we directly measure the flow into the eye when the pressure drop across the pressure-dependent pathways is eliminated. Using this approach we address i) the magnitude of pressure-independent flow in ex vivo eyes, ii) whether we can accurately measure an artificially imposed pressure-independent flow, and iii) whether the presence of a pressure-independent flow affects our ability to measure outflow facility. These studies are conducted in mice, which are a common animal model for aqueous humour dynamics. In eyes perfused with a single cannula, the average pressure-independent flow was 1 [-3, 5] nl/min (mean [95% confidence interval]) (N = 6). Paired ex vivo eyes were then cannulated with two needles, connecting the eye to both iPerfusion and a syringe pump, which was used to impose a known pressure-independent flow of 120 nl/min into the experimental eye only. The measured pressure-independent flow was then 121 [117, 125] nl/min (N = 7), indicating that the method could measure pressure-independent flow with high accuracy. Finally, we showed that the artificially imposed pressure-independent flow did not affect our ability to measure facility, provided that the pressure-dependence of facility and the true pressure-independent flow were accounted for. The present study provides a robust method for measurement of pressure-independent flow, and demonstrates the importance of accurately quantifying this

  15. Foam Optics and Mechanics

    NASA Technical Reports Server (NTRS)

    Durian, Douglas J.; Zimmerli, Gregory A.

    2002-01-01

    The Foam Optics and Mechanics (FOAM) project will exploit the microgravity environment to more accurately measure the rheological and optical characteristics of wet aqueous foams. Using both rheology and laser light scattering diagnostics, the goal is to quantify the unusual elastic character of foams in terms of their underlying microscopic structure and dynamics. Of particular interest is determining how the elastic character vanishes, i.e., how the foam 'melts' into a simple viscous liquid, as a function of both increasing liquid content and increasing shear strain rate. The unusual elastic character of foams will be quantified macroscopically by measurement of the shear stress as a function of shear strain rate and of time following a step strain. Such data will be analyzed in terms of a yield stress, shear moduli, and dynamical time scales. Microscopic information about bubble packing and rearrangement dynamics, from which the macroscopic non-Newtonian properties ultimately arise, will be obtained non-invasively by multiple-light scattering: diffuse transmission spectroscopy (DTS) and diffusing wave spectroscopy (DWS). Quantitative trends with materials parameters, most importantly average bubble size and liquid content, will be sought in order to elucidate the fundamental connection between the microscopic structure and dynamics and the macroscopic rheology.

  16. Pathways to low-cost electrochemical energy storage: a comparison of aqueous and nonaqueous flow batteries

    SciTech Connect

    Darling, Robert M.; Gallagher, Kevin G.; Kowalski, Jeffrey A.; Ha, Seungbum; Brushett, Fikile R.

    2014-11-01

    Energy storage is increasingly seen as a valuable asset for electricity grids composed of high fractions of intermittent sources, such as wind power or, in developing economies, unreliable generation and transmission services. However, the potential of batteries to meet the stringent cost and durability requirements for grid applications is largely unquantified. We investigate electrochemical systems capable of economically storing energy for hours and present an analysis of the relationships among technological performance characteristics, component cost factors, and system price for established and conceptual aqueous and nonaqueous batteries. We identified potential advantages of nonaqueous flow batteries over those based on aqueous electrolytes; however, new challenging constraints burden the nonaqueous approach, including the solubility of the active material in the electrolyte. Requirements in harmony with economically effective energy storage are derived for aqueous and nonaqueous systems. The attributes of flow batteries are compared to those of aqueous and nonaqueous enclosed and hybrid (semi-flow) batteries. Flow batteries are a promising technology for reaching these challenging energy storage targets owing to their independent power and energy scaling, reliance on facile and reversible reactants, and potentially simpler manufacture as compared to established enclosed batteries such as lead–acid or lithium-ion.

  17. Visualizing oil displacement with foam in a microfluidic device with permeability contrast.

    PubMed

    Conn, Charles A; Ma, Kun; Hirasaki, George J; Biswal, Sibani Lisa

    2014-10-21

    Foam mobility control and novel oil displacement mechanisms were observed in a microfluidic device representing a porous media system with layered permeability. Foam was pre-generated using a flow-focusing microfluidic device and injected into an oil-wet, oil-saturated 2-D PDMS microfluidic device. The device is designed with a central fracture flanked by high-permeability and low-permeability zones stratified in the direction of injection. A 1 : 1, 1% blend of alpha olefin sulfonate 14-16 (AOS) and lauryl betaine (LB) surfactants produced stable foam in the presence of paraffin oil. The oil saturation and pressure drop across the microfluidic device were measured as a function of time and the injected pore volume, indicating an increase in apparent viscosity for foam with an accompanying decrease in oil saturation. In contrast to the control experiments, foam was shown to more effectively mobilize trapped oil by increasing the flow resistance in the fracture and high-permeability zones and by diverting the surfactant solution into adjacent low-permeability zones. The foam was observed to separate into gas-rich and aqueous-rich phases depending on matrix permeability, suggesting that it is not appropriate to treat foam as a homogeneous dispersion of gas and liquid.

  18. Experimental investigation of foam spread and extinguishment of the large-scale methanol pool fire.

    PubMed

    Zhang, Qinglin; Wang, Lu; Bi, Yixing; Xu, Dajun; Zhi, Huiqiang; Qiu, Peifang

    2015-04-28

    A steel channel with the size of 30m×2 m×1.2m has been made to simulate the full surface fire of a 50,000m(3) methanol tank. Several large-scale methanol fire extinguishment experiments have been conducted under different foam application rates and foam concentrations in order to investigate the flow length, flow velocity and fire extinguishing effectiveness of the alcohol-resistant foam. The result showed that the alcohol-resistant aqueous film forming foam (AFFF/AR) and alcohol-resistant fluoro-protein foam (FP/AR) could flow beyond 30m on the burning methanol surface and extinguish the fire successfully even with the foam application rate of 4Lmin(-1)m(-2). Under the same condition, the fire extinguishing performance of AFFF/AR was better than FP/AR, and the flow velocity of AFFF/AR on the burning methanol surface was 0.203ms(-1), while the value of FP/AR was 0.082ms(-1).

  19. Historical usage of aqueous film forming foam: a case study of the widespread distribution of perfluoroalkyl acids from a military airport to groundwater, lakes, soils and fish.

    PubMed

    Filipovic, Marko; Woldegiorgis, Andreas; Norström, Karin; Bibi, Momina; Lindberg, Maria; Österås, Ann-Helen

    2015-06-01

    Historical usage of aqueous film forming foams (AFFFs) at military airports is a potential source of perfluoroalkyl acids (PFAAs) to the nearby environment. In this study, the distribution of perfluorohexanoic acid (PFHxA), perfluorooctanoic acid (PFOA), perfluorohexane sulfonate (PFHxS) and perfluorooctane sulfonate (PFOS) in soil, groundwater, surface water, tap water well, and fish muscle was investigated at a closed down military airfield (F18) and its surroundings in Stockholm, Sweden. The presence of PFOS at AFFF training sites was inventoried. One major finding of the study is that a former airfield, abandoned since 1994, may still be a point source of PFAAs to nearby recipients. PFOS and PFOA were ubiquitous in the soil samples at former AFFF training sites with concentrations ranging from 2.18 to 8520ngg(-1) dry weight and <0.12-287ngg(-1) dry weight respectively. The sum of PFAAs in the groundwater and surface waters ranged from 738 to 51000ngL(-1) and

  20. Foaming properties of wheat gliadin.

    PubMed

    Thewissen, Bert G; Celus, Inge; Brijs, Kristof; Delcour, Jan A

    2011-02-23

    We studied gliadin solubility, surface tension and foam behavior, and the presence of different gliadin types in gliadin aqueous solutions and foams as a function of pH. Gliadin has excellent foaming properties only at neutral and alkaline pH. Its solubility is minimal near neutral pH, while almost complete at acidic and alkaline pH. Surface tensions of gliadin solutions are minimal around neutral pH, higher at alkaline pH, and highest at acidic pH, which corresponds well with their respective foaming properties. Foams at acidic and alkaline pH values are enriched in γ-gliadin, while foams at pH 8.0 have a similar distribution of α- and γ-gliadins. Thus, γ-gliadin predominantly contributes to the foaming properties of gliadin. The poor foaming properties of gliadin at pH 2.0 improve in the presence of 0.25 and 1.0% NaCl. It follows that the presence of positively charged amino acid residues hinders the formation of stable foam at acidic pH.

  1. Smoothed particle hydrodynamics model of non-aqueous phase liquid flow and dissolution

    SciTech Connect

    Tartakovsky, Alexandre M.; Meakin, Paul; Ward, Anderson L.

    2009-01-01

    A smoothed particle hydrodynamics model was developed to simulate the flow of mixtures of aqueous and non-aqueous phase liquids in porous media and the dissolution of the non-aqueous phase in the aqueous phase. The model was used to study the effects of pore-scale heterogeneity and anisotropy on the steady state dense non-aqueous phase liquid (DNAPL) saturation when gravity driven DNAPL displaces water from initially water saturated porous media. Pore-scale anisotropy was created by using co-oriented non overlapping elliptically shaped grains to represent the porous media. After a steady state DNAPL saturation was reached, water was injected until a new steady state DNAPL saturation was reached. The amount of trapped DNAPL was found to be greater when DNAPL is displaced in the direction of the major axes of the soil grains than when it is displaced in the direction of the minor axes of the soil grains. The amount of trapped DNAPL was also found to increase with decreasing initial saturation of the continuous DNAPL phase. For the conditions used in our simulations, the saturation of the trapped NAPL with a smaller initial DNAPL saturation was more than 3 times larger than the amount of trapped DNAPL with a larger initial saturation. These simulations were carried out assuming that the DNAPL did not dissolve in water. Simulations including the effect of dissolution of DNAPL in the aqueous phase were also performed, and effective (macroscopic) mass transfer coefficients were determined.

  2. An Ambient Temperature Molten Sodium-Vanadium Battery with Aqueous Flowing Catholyte.

    PubMed

    Liu, Caihong; Shamie, Jack S; Shaw, Leon L; Sprenkle, Vincent L

    2016-01-20

    In this study, we have investigated the key factors dictating the cyclic performance of a new type of hybrid sodium-based flow batteries (HNFBs) that can operate at room temperature with high cell voltages (>3 V), multiple electron transfer redox reactions per active ion, and decoupled design of power and energy. HNFBs are composed of a molten Na-Cs alloy anode, flowing aqueous catholyte, and a Na-β″-Al2O3 solid electrolyte as the separator. The surface functionalization of graphite felt electrodes for the flowing aqueous catholyte has been studied for its effectiveness in enhancing V(2+)/V(3+), V(3+)/V(4+), and V(4+)/V(5+) redox couples. The V(4+)/V(5+) redox reaction has been further investigated at different cell operation temperatures for its cyclic stability and how the properties of the solid electrolyte membrane play a role in cycling. These fundamental understandings provide guidelines for improving the cyclic performance and stability of HNFBs with aqueous catholytes. We show that the HNFB with aqueous V-ion catholyte can reach high storage capacity (∼70% of the theoretical capacity) with good Coulombic efficiency (90% ± 1% in 2-30 cycles) and cyclic performance (>99% capacity retention for 30 cycles). It demonstrates, for the first time, the potential of high capacity HNFBs with aqueous catholytes, good capacity retention and long cycling life. This is also the first demonstration that Na-β″-Al2O3 solid electrolyte can be used with aqueous electrolyte at near room temperature for more than 30 cycles.

  3. Analysis on Experimental Investigation and Mathematical Modeling of Incompressible Flow Through Ceramic Foam Filters

    NASA Astrophysics Data System (ADS)

    Akbarnejad, Shahin; Jonsson, Lage Tord Ingemar; Kennedy, Mark William; Aune, Ragnhild Elizabeth; Jönsson, Pӓr Göran

    2016-08-01

    This paper presents experimental results of pressure drop measurements on 30, 50, and 80 pores per inch (PPI) commercial alumina ceramic foam filters (CFF) and compares the obtained pressure drop profiles to numerically modeled values. In addition, it is aimed at investigating the adequacy of the mathematical correlations used in the analytical and the computational fluid dynamics (CFD) simulations. It is shown that the widely used correlations for predicting pressure drop in porous media continuously under-predict the experimentally obtained pressure drop profiles. For analytical predictions, the negative deviations from the experimentally obtained pressure drop using the unmodified Ergun and Dietrich equations could be as high as 95 and 74 pct, respectively. For the CFD predictions, the deviation to experimental results is in the range of 84.3 to 88.5 pct depending on filter PPI. Better results can be achieved by applying the Forchheimer second-order drag term instead of the Brinkman-Forchheimer drag term. Thus, the final deviation of the CFD model estimates lie in the range of 0.3 to 5.5 pct compared to the measured values.

  4. Effect of Associative Polymers on the Foaming Properties of Surfactant Solutions

    NASA Astrophysics Data System (ADS)

    Cervantes, Alfredo; Robles, Emmanuel; Acuña, Heriberto; Gamez, Rogelio; Maldonado, Amir

    2006-03-01

    Aqueous foams are materials which have many industrial applications. Their stability is affected by three mechanisms: bubble coalescence (film rupture), coarsening (gas diffusion) and drainage (gravity-driven liquid flow). The aim of this work is to obtain some insight into the effect of associative polymers on the foamability, foam stability and drainage of surfactant solutions. The foams were produced by air bubbling and by the turbulent mixing method. The surfactant is SDS and the associative polymers studied are HEUR and POE-Stearate. We studied the effect of polymer concentration for each macromolecule. The results show that two opposite effects are present when the polymer concentration is increased: for low polymer concentrations, foamability and foam stability is higher than for high concentrations. Results are discussed in terms of the properties of the solution: surface tension, electrical conductivity, bulk viscosity, etc.

  5. Epoxy Foam Encapsulants: Processing and Dielectric Characterization

    SciTech Connect

    Linda Domeier; Marion Hunter

    1999-01-01

    The dielectric performance of epoxy foams was investigated to determine if such materials might provide advantages over more standard polyurethane foams in the encapsulation of electronic assemblies. Comparisons of the dielectric characteristics of epoxy and urethane encapsulant foams found no significant differences between the two resin types and no significant difference between as-molded and machined foams. This study specifically evaluated the formulation and processing of epoxy foams using simple methylhydrosiloxanes as the flowing agent and compared the dielectric performance of those to urethane foams of similar density.

  6. Pathways to low-cost electrochemical energy storage: a comparison of aqueous and nonaqueous flow batteries

    DOE PAGES

    Darling, Robert M.; Gallagher, Kevin G.; Kowalski, Jeffrey A.; ...

    2014-11-01

    Energy storage is increasingly seen as a valuable asset for electricity grids composed of high fractions of intermittent sources, such as wind power or, in developing economies, unreliable generation and transmission services. However, the potential of batteries to meet the stringent cost and durability requirements for grid applications is largely unquantified. We investigate electrochemical systems capable of economically storing energy for hours and present an analysis of the relationships among technological performance characteristics, component cost factors, and system price for established and conceptual aqueous and nonaqueous batteries. We identified potential advantages of nonaqueous flow batteries over those based on aqueousmore » electrolytes; however, new challenging constraints burden the nonaqueous approach, including the solubility of the active material in the electrolyte. Requirements in harmony with economically effective energy storage are derived for aqueous and nonaqueous systems. The attributes of flow batteries are compared to those of aqueous and nonaqueous enclosed and hybrid (semi-flow) batteries. Flow batteries are a promising technology for reaching these challenging energy storage targets owing to their independent power and energy scaling, reliance on facile and reversible reactants, and potentially simpler manufacture as compared to established enclosed batteries such as lead–acid or lithium-ion.« less

  7. Development of Defoamers for Confinenment Foam

    SciTech Connect

    Hoffman, D M; Mitchell, A R

    2005-08-10

    Aqueous foam concentrate (AFC) 380 foam was developed by Sandia National Laboratory as a blast mitigation foam for unexploded ordnance (UXO) and its ''engineered foam structure'' is reported to be able to ''envelop chemical or biological aerosols'' [1]. It is similar to commercial fire-fighting foams, consisting mostly of water with small amounts of two alcohols, an ether and surfactant. It also contains xanthan gum, probably, to strengthen the foam film and delay drainage. The concentrate is normally diluted in a 6:94 ratio with water for foaming applications. The diluted solution is normally foamed with air to an expansion factor of about 100 (density 0.01 g/cc), which is called ''dry'' foam. Higher density foam (0.18 > {rho} > 0.03 g/cc) was discovered which had quite different characteristics from ''dry'' foam and was called ''wet'' foam. Some characterization of these foams has also been carried out, but the major effort described in this document is the evaluation, at the small and medium scale, of chemical, mechanical and thermal approaches to defoaming AFC 380 foam. Several chemical approaches to defoaming were evaluated including oxidation and precipitation of the xanthan, use of commercial oil-emulsion or suspension defoamers, pH modification, and cation exchange with the surfactant. Of these the commercial defoamers were most effective. Two mechanical approaches to defoaming were evaluated: pressure and foam rupture with very fine particles. Pressure and vacuum techniques were considered too difficult for field applications but high surface area silica particles worked very well on dry foam. Finally simple thermal techniques were evaluated. An order-disorder transition occurs in xanthan solutions at about 60 C, which may be responsible for the effectiveness of hot air as a defoamer. During defoaming of 55 gallons of foam with hot air, after about 70% of the AFC 380 foam had been defoamed, the effectiveness of hot air was dramatically reduced

  8. Size and composition of foam droplets with applications to the marine atmosphere and nanoparticle synthesis

    NASA Astrophysics Data System (ADS)

    Tyree, Corey A.

    Foams are used in chemical engineering to separate constituents from the bulk liquid. The industrial foam separation method, known as bubble fractionation, ends with an enriched foam being skimmed from the liquid. Foam bubble bursting, which produces aerosol droplets (i.e. foam droplets), can also result in separation. Like bubble fractionation, foam droplet separation relies on interfacial mass transport to separate material from solution. In this process, the separation ends with the formation of aerosol droplets. The objectives of this work were to (1) study foam droplet separation for naturally occurring oceanic whitecap foams and (2) to generate nanoparticles using foam droplet separation. Sea salt aerosol (SSA) particles are routinely observed in the remote marine boundary layer (MBL); these aerosols include cloud condensation nuclei and so affect the earth's radiative balance. Here foams designed to mimic oceanic whitecaps were generated in the laboratory using a range of bubbling flow rates and aqueous media: unfiltered seawater, filtered seawater, artificial seawater, and mixtures of filtered and artificial seawater. The number and sizes of dried foam droplets in the particle diameter range 0.015--0.67 mum were measured; an impactor was also used to collect droplets in the size range 0.056--18 mum. Collectively, the results indicate that foam droplet size distributions are bimodal with mass modes in the aerodynamic diameter ranges at 80% relative humidity of 0.56--1 mum and 1.8--2.5 mum. The submicrometer foam droplet mode, which corresponds to a number size distribution mode at a dry diameter of 100 nm, falls within the range of reported mean diameters (dry diameter = 40--200 nm) for submicrometer SSA particles observed in the remote MBL. A novel approach to nanoscale separation under ambient conditions was developed whereby foam bubble bursting produces aerosol droplets. The ability of the foam aerosol cycle to produce useful nanoparticles was

  9. Flow Boiling Heat Transfer to Lithium Bromide Aqueous Solution in Subcooled Region

    NASA Astrophysics Data System (ADS)

    Kaji, Masao; Furukawa, Masahiro; Nishizumi, Takeharu; Ozaki, Shinji; Sekoguchi, Kotohiko

    A theoretical prediction model of the boiling heat transfer coefficient in the subcooled region for water and lithium bromide aqueous solution flowing in a rectangular channel is proposed. In the present heat transfer model, a heat flux is assumed to consist of both the forced convective and the boiling effect components. The forced convective component is evaluated from the empirical correlation of convective heat transfer coefficient for single-phase flow considering the effect of increase of liquid velocity due to net vapor generation. Empirical correlations for determining the heat flux due to the boiling effect and the quality at the onset point of net vapor generation are obtained from the data presented in the first report1). Agreement between the present theoretical prediction and the experimental data is satisfactorily good both for water and lithium bromide aqueous solution.

  10. Zero-valent iron removal rates of aqueous Cr(VI) measured under flow conditions

    SciTech Connect

    Kaplan, Daniel I.; Gilmore, Tyler J.

    2004-06-30

    The rates of Cr(VI) removal from the aqueous phase by zero-valent iron Fe(0) was measured under flow conditions. The intent of this work was to generate removal rate coefficients that would be applicable to the Reactive Well Technology, a gournwater remediation technology that replaces the sand in a filter pack of a conventioanl well with a reactive material, such as Fe(0).

  11. Foam invasion through a single pore.

    PubMed

    Delbos, Aline; Pitois, Olivier

    2011-07-01

    We investigate experimentally the behavior of liquid foams pumped at a given flow rate through a single pore, in the situation where the pore diameter is smaller than the bubble diameter. Results reveal that foam invasion can be observed only within a restricted range of values for the dimensionless flow rate and the foam liquid fraction. Within this foam invasion regime, the liquid content of invading foams is measured to be three times higher than the initial liquid content. Outside this regime, both gas alone and liquid alone invasion regimes can be observed. The gas invasion regime results from the rupture of foam films during local T1, during bubble rearrangements events induced by foam flow, whereas the liquid invasion regime is allowed by the formation of a stable cluster of jammed bubbles at the pore's opening.

  12. Simulation Study of Nano Aqueous Flow Sensor Based on Amperometric Measurement

    PubMed Central

    Wu, Jian; Zhou, Qingli; Liu, Jun; Lou, Zhengguo

    2006-01-01

    In this paper, a novel nano aqueous flow sensor which consists of two closely spaced amperometric sensors is investigated by digital simulation. The simulation results indicate that the ratio of the responses of two closely spaced amperometric sensors is only related to flow rates in the channel, insensitive to the analyte concentration in the solution. By comparing the output of two amperometric sensors, the flow rate in the channel can be deduced. It is not necessary to determine the analyte concentration in advance. The simulation results show it is able to detect flow rate by in the range of several nano-liters per minute when the distance between the working electrodes of two amperometric sensors is 200 nm and the cross-section of the channel is 1 μm × 1 μm.

  13. Polyimide foams

    NASA Technical Reports Server (NTRS)

    Gagliani, John (Inventor); Lee, Raymond (Inventor); Sorathia, Usman A. K. (Inventor)

    1982-01-01

    Copolymide foams derived from a diester of 3,3',4,4'-benzophenonetetracarboxylic acid, an aromatic diamine, and a heterocyclic diamine. A molar concentration of the heterocyclic diamine approaching but not exceeding 0.42 is employed. This results in a flexible foam with a homogeneous cellular structure and a reduced compression set loss.

  14. Polyimide foams

    NASA Technical Reports Server (NTRS)

    Gagliani, John (Inventor); Lee, Raymond (Inventor); Sorathia, Usman A. K. (Inventor)

    1983-01-01

    Copolyimide foams derived from a diester of 3,3',4,4'-benzophenonetetracarboxylic acid, an aromatic diamine, and a heterocyclic diamine. A molar concentration of the heterocyclic diamine approaching but not exceeding 0.42 is employed. This results in a flexible foam with a homogeneous cellular structure and a reduced compression set loss.

  15. Polyimide foams

    NASA Technical Reports Server (NTRS)

    Gagliani, John (Inventor); Lee, Raymond (Inventor); Sorathia, Usman A. K. (Inventor)

    1982-01-01

    Copolyimide foams derived from a diester of 3,3',4,4'-benzophenonetetracarboxylic acid, an aromatic diamine, and a heterocyclic diamine. A molar concentration of the heterocyclic diamine approaching but not exceeding 0.42 is employed. This results in a flexible foam with a homogeneous cellular structure and a reduced compression set loss.

  16. Composite foams

    DOEpatents

    Williams, Jr., Joel M.; Nyitray, Alice M.; Wilkerson, Mark H.

    1991-01-01

    Composite foams are provided comprising a first rigid, microcellular, open-celled organic polymer foam having a density of from about 0.015 g/cm.sup.3 to about 0.20 g/cm.sup.3 and a pore size of from about 1 micron to about 30 microns, said first foam containing a second polymer having a density of from about 0.015 g/cm.sup.3 to about 0.20 g/cm.sup.3 or a second polymer foam having a density of from about 0.015 g/cm.sup.3 to about 0.20 g/cm.sup.3 and a pore size of from about 0.01 microns to about 1.0 micron within the open cells of said first foam.

  17. Composite foams

    DOEpatents

    Williams, Jr., Joel M.; Nyitray, Alice M.; Wilkerson, Mark H.

    1990-01-01

    Composite foams are provided comprising a first rigid, microcellular, open-celled organic polymer foam having a density of from about 0.015 g/cm.sup.3 to about 0.20 g/cm.sup.3 and a pore size of from about 1 micron to about 30 microns, said first foam containing a second polymer having a density of from about 0.015 g/cm.sup.3 to about 0.20 g/cm.sup.3 or a second polymer foam having a density of from about 0.015 g/cm.sup.3 to about 0.20 g/cm.sup.3 and a pore size of from about 0.01 microns to about 1.0 micron within the open cells of said first foam.

  18. Enhanced rhamnolipids production via efficient foam-control using stop valve as a foam breaker.

    PubMed

    Long, Xuwei; Shen, Chong; He, Ni; Zhang, Guoliang; Meng, Qin

    2017-01-01

    In this study, a stop valve was used as a foam breaker for dealing with the massive overflowing foam in rhamnolipid fermentation. As found, a stop valve at its tiny opening could break over 90% of the extremely stable rhamnolipid foam into enriched liquid when foam flows through the sharp gap in valve. The efficient foam-control by the stop valve considerably improved the rhamnolipid fermentation and significantly enhanced the rhamnolipid productivity by 83% compared to the regular fermentation. This efficient foam breaking was mainly achieved by a high shear rate in combination with fast separation of air from the collapsed foam. Altogether, the stop valve possessed a great activity in breaking rhamnolipid foam, and the involving mechanism holds the potential for developing efficient foam breakers for industrial rhamnolipid fermentation.

  19. Separation of endosomes by aqueous two-phase partition and free-flow electrophoresis.

    PubMed

    Morré, D J; Morré, D M; Van Alstine, J M

    1998-06-26

    We have developed two endosome models to evaluate the separation of endosome populations by aqueous two-phase partition. In the first model, bovine kidney endosomes were used. In the second model. HeLa endosomes were identified in homogenates by means of a latent drug-(capsaicin-)inhibited NADH oxidase (NOX). Endosomes were first isolated by aqueous two-phase partition. To separate early and late endosomes, the endosomes were incubated with ATP to acidify the endosome interiors by activating a proton-translocating ATPase. Thus far, we have been able to resolve the early and late endosomes from any source only by preparative free-flow electrophoresis and not by phase-partition. Previous studies have shown that gravitational forces may be important for separation of endosomes by phase partition. Low-speed centrifugation (< or =12.5 g) during phase resolution altered the activity of the latent NADH oxidase used as a marker for HeLa cell endosomes.

  20. Investigating the effects of varying the angle of application and increasing the ignition source flow rate during ISO ignitability testing on foam and vinyl.

    PubMed

    Walker, Lloyd; Svistounov, Alexander; Symonds, Ben; Hobbs, David

    2012-01-01

    To investigate how, and to what extent, the following factors influence burn damage: (1) the angle of application of the ignition source to the sample surface, and (2) the flow rate for the ignition source, when assessing samples in accordance with ISO 8191-2:1988. Varying the ignition source flow rate and the angle of application of the ignition source to the sample undergoing testing, which are both variations on the existing procedure outlined in the Standard ISO 8191-2:1988. Burn damage as measured by the depth (if applicable) and greatest horizontal and vertical dimensions. Increasing the ignition source gas flow rate (from 45 ml/min to 240 ml/min) increased the measured burn damage for both foam and vinyl samples. The increased damage factor was at least two-fold (and up to five-fold). Changing the angle of application of the ignition source (45 degrees compared to 0 degrees) did not significantly affect the measured burn damage for either sample. These findings indicate that the direction of application of a match-flame equivalent ignition source has no significant affect on the resulting burn damage, but that increasing the ignition source flow rate increases the burn damage for both foam and vinyl samples.

  1. High-energy-density, aqueous, metal-polyiodide redox flow batteries

    DOEpatents

    Li, Bin; Nie, Zimin; Wang, Wei; Liu, Jun; Sprenkle, Vincent L.

    2017-08-29

    Improved metal-based redox flow batteries (RFBs) can utilize a metal and a divalent cation of the metal (M.sup.2+) as an active redox couple for a first electrode and electrolyte, respectively, in a first half-cell. For example, the metal can be Zn. The RFBs can also utilize a second electrolyte having I.sup.-, anions of I.sub.x (for x.gtoreq.3), or both in an aqueous solution, wherein the I.sup.- and the anions of I.sub.x (for x.gtoreq.3) compose an active redox couple in a second half-cell.

  2. Forming foam structures with carbon foam substrates

    SciTech Connect

    Landingham, Richard L.; Satcher, Jr., Joe H.; Coronado, Paul R.; Baumann, Theodore F.

    2012-11-06

    The invention provides foams of desired cell sizes formed from metal or ceramic materials that coat the surfaces of carbon foams which are subsequently removed. For example, metal is located over a sol-gel foam monolith. The metal is melted to produce a metal/sol-gel composition. The sol-gel foam monolith is removed, leaving a metal foam.

  3. Domain Growth Kinetics in Stratifying Foam Films

    NASA Astrophysics Data System (ADS)

    Zhang, Yiran; Sharma, Vivek

    2015-03-01

    Baking bread, brewing cappuccino, pouring beer, washing dishes, shaving, shampooing, whipping eggs and blowing bubbles all involve creation of aqueous foam films. Typical foam films consist of two surfactant-laden surfaces that are μ 5 nm - 10 micron apart. Sandwiched between these interfacial layers is a fluid that drains primarily under the influence of viscous and interfacial forces, including disjoining pressure. Interestingly, for certain low molecular weight surfactants, a layered ordering of micelles inside the foam films (thickness <100 nm) leads to a stepwise thinning phenomena called stratification. We experimentally elucidate the influence of these different driving forces, and confinement on drainage kinetics of horizontal stratifying foam films. Thinner, darker domains spontaneously grow within foam films. Quantitative characterization of domain growth visualized in a using Scheludko-type thin film cell and a theoretical model based on lubrication analysis, provide critical insights into hydrodynamics of thin foam films, and the strength and nature of surface forces, including supramolecular oscillatory structural forces.

  4. Foam patterns

    DOEpatents

    Chaudhry, Anil R; Dzugan, Robert; Harrington, Richard M; Neece, Faurice D; Singh, Nipendra P; Westendorf, Travis

    2013-11-26

    A method of creating a foam pattern comprises mixing a polyol component and an isocyanate component to form a liquid mixture. The method further comprises placing a temporary core having a shape corresponding to a desired internal feature in a cavity of a mold and inserting the mixture into the cavity of the mold so that the mixture surrounds a portion of the temporary core. The method optionally further comprises using supporting pins made of foam to support the core in the mold cavity, with such pins becoming integral part of the pattern material simplifying subsequent processing. The method further comprises waiting for a predetermined time sufficient for a reaction from the mixture to form a foam pattern structure corresponding to the cavity of the mold, wherein the foam pattern structure encloses a portion of the temporary core and removing the temporary core from the pattern independent of chemical leaching.

  5. Allometry and Scaling of the Intraocular Pressure and Aqueous Humour Flow Rate in Vertebrate Eyes.

    PubMed

    Zouache, Moussa A; Eames, Ian; Samsudin, Amir

    2016-01-01

    In vertebrates, intraocular pressure (IOP) is required to maintain the eye into a shape allowing it to function as an optical instrument. It is sustained by the balance between the production of aqueous humour by the ciliary body and the resistance to its outflow from the eye. Dysregulation of the IOP is often pathological to vision. High IOP may lead to glaucoma, which is in man the second most prevalent cause of blindness. Here, we examine the importance of the IOP and rate of formation of aqueous humour in the development of vertebrate eyes by performing allometric and scaling analyses of the forces acting on the eye during head movement and the energy demands of the cornea, and testing the predictions of the models against a list of measurements in vertebrates collated through a systematic review. We show that the IOP has a weak dependence on body mass, and that in order to maintain the focal length of the eye, it needs to be an order of magnitude greater than the pressure drop across the eye resulting from gravity or head movement. This constitutes an evolutionary constraint that is common to all vertebrates. In animals with cornea-based optics, this constraint also represents a condition to maintain visual acuity. Estimated IOPs were found to increase with the evolution of terrestrial animals. The rate of formation of aqueous humour was found to be adjusted to the metabolic requirements of the cornea, scaling as Vac(0.67), where Vac is the volume of the anterior chamber. The present work highlights an interdependence between IOP and aqueous flow rate crucial to ocular function that must be considered to understand the evolution of the dioptric apparatus. It should also be taken into consideration in the prevention and treatment of glaucoma.

  6. Allometry and Scaling of the Intraocular Pressure and Aqueous Humour Flow Rate in Vertebrate Eyes

    PubMed Central

    Zouache, Moussa A.; Eames, Ian; Samsudin, Amir

    2016-01-01

    In vertebrates, intraocular pressure (IOP) is required to maintain the eye into a shape allowing it to function as an optical instrument. It is sustained by the balance between the production of aqueous humour by the ciliary body and the resistance to its outflow from the eye. Dysregulation of the IOP is often pathological to vision. High IOP may lead to glaucoma, which is in man the second most prevalent cause of blindness. Here, we examine the importance of the IOP and rate of formation of aqueous humour in the development of vertebrate eyes by performing allometric and scaling analyses of the forces acting on the eye during head movement and the energy demands of the cornea, and testing the predictions of the models against a list of measurements in vertebrates collated through a systematic review. We show that the IOP has a weak dependence on body mass, and that in order to maintain the focal length of the eye, it needs to be an order of magnitude greater than the pressure drop across the eye resulting from gravity or head movement. This constitutes an evolutionary constraint that is common to all vertebrates. In animals with cornea-based optics, this constraint also represents a condition to maintain visual acuity. Estimated IOPs were found to increase with the evolution of terrestrial animals. The rate of formation of aqueous humour was found to be adjusted to the metabolic requirements of the cornea, scaling as Vac0.67, where Vac is the volume of the anterior chamber. The present work highlights an interdependence between IOP and aqueous flow rate crucial to ocular function that must be considered to understand the evolution of the dioptric apparatus. It should also be taken into consideration in the prevention and treatment of glaucoma. PMID:26990431

  7. Maximizing the power density of aqueous electrochemical flow cells with in operando deposition

    NASA Astrophysics Data System (ADS)

    Goulet, Marc-Antoni; Ibrahim, Omar A.; Kim, Will H. J.; Kjeang, Erik

    2017-01-01

    To transition toward sustainable energy systems, next generation power sources must provide high power density at minimum cost. Using inexpensive and environmentally friendly fabrication methods, this work describes a room temperature electrochemical flow cell with a maximum power density of 2.01 W cm-2 or 13.4 W cm-3. In part, this is achieved by minimizing ohmic resistance through decreased electrode spacing, implementation of current collectors and improvement of electrolyte conductivity. The majority of the performance gain is provided by a novel in operando dynamic flowing deposition method for which the cell design has been optimized. Carbon nanotubes (CNTs) are deposited dynamically at the entrance of and within the carbon paper electrodes during operation of the cell. A natural equilibrium is reached between deposition and detachment of CNTs at which the electrochemical surface area and pore size distribution of the flow-through porous electrodes are greatly enhanced. In this way, the novel deposition method more than doubles the power density of the cell and sets a new performance benchmark for what is practically attainable with aqueous electrochemical flow cells. Overall, it is expected that the design and operation methods illustrated here will enable a wide range of electrochemical flow cell technologies to achieve optimal performance.

  8. Ambipolar zinc-polyiodide electrolyte for a high-energy density aqueous redox flow battery

    DOE PAGES

    Li, Bin; Nie, Zimin; Vijayakumar, M.; ...

    2015-02-24

    Large-scale energy storage systems are crucial for substantial deployment of renewable energy sources. Energy storage systems with high energy density, high safety, and low cost and environmental friendliness are desired. To overcome the major limitations of the current aqueous redox flow battery systems, namely lower energy density (~25 Wh L-1) and presence of strong acids and/or other hazardous, a high energy density aqueous zinc/polyiodide flow battery (ZIB) is designed with near neutral ZnI2 solutions as catholytes. The energy density of ZIB could reach 322 Wh L-1 at the solubility limit of ZnI2 in water (~7 M). We demonstrate charge andmore » discharge energy densities of 245.9 Wh/L and 166.7 Wh L-1 with ZnI2 electrolyte at 5.0 M, respectively. The addition of ethanol (EtOH) in ZnI2 electrolyte can effectively mitigate the growth of zinc dendrite at the anode and improve the stability of catholytes with wider temperature window (-20 to 50°C), which enable ZIB system to be a promising alternative as a high-energy and high- safety stationary energy storage system.« less

  9. Ambipolar zinc-polyiodide electrolyte for a high-energy density aqueous redox flow battery

    SciTech Connect

    Li, Bin; Nie, Zimin; Vijayakumar, M.; Li, Guosheng; Liu, Jun; Sprenkle, Vincent L.; Wang, Wei

    2015-02-24

    Large-scale energy storage systems are crucial for substantial deployment of renewable energy sources. Energy storage systems with high energy density, high safety, and low cost and environmental friendliness are desired. To overcome the major limitations of the current aqueous redox flow battery systems, namely lower energy density (~25 Wh L-1) and presence of strong acids and/or other hazardous, a high energy density aqueous zinc/polyiodide flow battery (ZIB) is designed with near neutral ZnI2 solutions as catholytes. The energy density of ZIB could reach 322 Wh L-1 at the solubility limit of ZnI2 in water (~7 M). We demonstrate charge and discharge energy densities of 245.9 Wh/L and 166.7 Wh L-1 with ZnI2 electrolyte at 5.0 M, respectively. The addition of ethanol (EtOH) in ZnI2 electrolyte can effectively mitigate the growth of zinc dendrite at the anode and improve the stability of catholytes with wider temperature window (-20 to 50°C), which enable ZIB system to be a promising alternative as a high-energy and high- safety stationary energy storage system.

  10. Drainage in a rising foam.

    PubMed

    Yazhgur, Pavel; Rio, Emmanuelle; Rouyer, Florence; Pigeonneau, Franck; Salonen, Anniina

    2016-01-21

    Rising foams created by continuously blowing gas into a surfactant solution are widely used in many technical processes, such as flotation. The prediction of the liquid fraction profile in such flowing foams is of particular importance since this parameter controls the stability and the rheology of the final product. Using drift flux analysis and recently developed semi-empirical expressions for foam permeability and osmotic pressure, we build a model predicting the liquid fraction profile as a function of height. The theoretical profiles are very different if the interfaces are considered as mobile or rigid, but all of our experimental profiles are described by the model with mobile interfaces. Even the systems with dodecanol are well known to behave as rigid in forced drainage experiments. This is because in rising foams the liquid fraction profile is fixed by the flux at the bottom of the foam. Here the foam is wet with higher permeability and the interfaces are not in equilibrium. These results demonstrate once again that it is not only the surfactant system that controls the mobility of the interface, but also the hydrodynamic problem under consideration. For example liquid flow through the foam during generation or in forced drainage is intrinsically different.

  11. Construction of hierarchical CNT/rGO supported MnMoO4 nanosheets on Ni foam for high performance aqueous hybrid supercapacitors.

    PubMed

    Mu, Xuemei; Du, Jingwei; Zhang, Yaxiong; Liang, Zhilin; Wang, Huan; Huang, Baoyu; Zhou, Jin Yuan; Pan, Xiaojun; Zhang, Zhenxing; Xie, Erqing

    2017-09-26

    Rationally designed conductive hierarchical nanostructures are highly desirable to support pseudocapacitive materials in achieving high-performance electrodes for supercapacitors. Herein, manganese molybdate nanosheets were hydrothermally grown with graphene oxide (GO) on three-dimensional nickel foam-supported carbon nanotube structures. Under the optimal graphene oxide concentration, the obtained carbon nanotubes/reduced graphene oxide/MnMoO4 composites (CNT/rGO/MnMoO4) as binder-free supercapacitor cathode perform a high specific capacitance of 2374.9 F g(-1) at the scan rate of 2 mV s(-1) and good long-term stability (97.1% of the initial specific capacitance can be maintained after 3000 charge/discharge cycles).The asymmetric device with CNT/rGO/MnMoO4 as the cathode electrode and the carbon nanotubes/activated carbon on nickel foam (CNT-AC) as the anode electrode can deliver an energy density of 59.4 Wh kg(-1) at the power density of 1367.9 W kg(-1). These superior performances can be attributed to the synergistic effects from each component of the composite electrodes: highly pseudocapacitive MnMoO4 nanosheets and three-dimensional conductive Ni foam/CNTs/rGO networks. These results suggest the fabricated asymmetric supercapacitor can be a promising candidate for energy storage devices.

  12. Metal-doped organic foam

    DOEpatents

    Rinde, James A.

    1982-01-01

    Organic foams having a low density and very small cell size and method for producing same in either a metal-loaded or unloaded (nonmetal loaded) form are described. Metal-doped foams are produced by soaking a polymer gel in an aqueous solution of desired metal salt, soaking the gel successively in a solvent series of decreasing polarity to remove water from the gel and replace it with a solvent of lower polarity with each successive solvent in the series being miscible with the solvents on each side and being saturated with the desired metal salt, and removing the last of the solvents from the gel to produce the desired metal-doped foam having desired density cell size, and metal loading. The unloaded or metal-doped foams can be utilized in a variety of applications requiring low density, small cell size foam. For example, rubidium-doped foam made in accordance with the invention has utility in special applications, such as in x-ray lasers.

  13. Critical transport issues for improving the performance of aqueous redox flow batteries

    NASA Astrophysics Data System (ADS)

    Zhou, X. L.; Zhao, T. S.; An, L.; Zeng, Y. K.; Wei, L.

    2017-01-01

    As the fraction of electricity generated from intermittent renewable sources (such as solar and wind) grows, developing reliable energy storage technologies to store electrical energy in large scale is of increasing importance. Redox flow batteries are now enjoying a renaissance and regarded as a leading technology in providing a well-balanced solution for current daunting challenges. In this article, state-of-the-art studies of the complex multicomponent transport phenomena in aqueous redox flow batteries, with a special emphasis on all-vanadium redox flow batteries, are reviewed and summarized. Rather than elaborating on the details of previous experimental and numerical investigations, this article highlights: i) the key transport issues in each battery's component that need to be tackled so that the rate capability and cycling stability of flow batteries can be significantly improved, ii) the basic mechanisms that control the active species/ion/electron transport behaviors in each battery's component, and iii) the key experimental and numerical findings regarding the correlations between the multicomponent transport processes and battery performance.

  14. Ambipolar zinc-polyiodide electrolyte for a high-energy density aqueous redox flow battery

    PubMed Central

    Li, Bin; Nie, Zimin; Vijayakumar, M.; Li, Guosheng; Liu, Jun; Sprenkle, Vincent; Wang, Wei

    2015-01-01

    Redox flow batteries are receiving wide attention for electrochemical energy storage due to their unique architecture and advantages, but progress has so far been limited by their low energy density (~25 Wh l−1). Here we report a high-energy density aqueous zinc-polyiodide flow battery. Using the highly soluble iodide/triiodide redox couple, a discharge energy density of 167 Wh l−1 is demonstrated with a near-neutral 5.0 M ZnI2 electrolyte. Nuclear magnetic resonance study and density functional theory-based simulation along with flow test data indicate that the addition of an alcohol (ethanol) induces ligand formation between oxygen on the hydroxyl group and the zinc ions, which expands the stable electrolyte temperature window to from −20 to 50 °C, while ameliorating the zinc dendrite. With the high-energy density and its benign nature free from strong acids and corrosive components, zinc-polyiodide flow battery is a promising candidate for various energy storage applications. PMID:25709083

  15. Ambipolar zinc-polyiodide electrolyte for a high-energy density aqueous redox flow battery.

    PubMed

    Li, Bin; Nie, Zimin; Vijayakumar, M; Li, Guosheng; Liu, Jun; Sprenkle, Vincent; Wang, Wei

    2015-02-24

    Redox flow batteries are receiving wide attention for electrochemical energy storage due to their unique architecture and advantages, but progress has so far been limited by their low energy density (~25 Wh l(-1)). Here we report a high-energy density aqueous zinc-polyiodide flow battery. Using the highly soluble iodide/triiodide redox couple, a discharge energy density of 167 Wh l(-1) is demonstrated with a near-neutral 5.0 M ZnI2 electrolyte. Nuclear magnetic resonance study and density functional theory-based simulation along with flow test data indicate that the addition of an alcohol (ethanol) induces ligand formation between oxygen on the hydroxyl group and the zinc ions, which expands the stable electrolyte temperature window to from -20 to 50 °C, while ameliorating the zinc dendrite. With the high-energy density and its benign nature free from strong acids and corrosive components, zinc-polyiodide flow battery is a promising candidate for various energy storage applications.

  16. Experimental and numerical investigations of ionic liquid-aqueous flow in microchannel

    NASA Astrophysics Data System (ADS)

    Li, Qi; Tsaoulidis, Dimitrios; Angeli, Panagiota

    2015-11-01

    The hydrodynamic characteristics of plug flow of an ionic liquid-aqueous two-phase system in a microchannel were studied experimentally and numerically. A mixture of 0.2M N-octyl(plenyl)-N,N-diisobutylcarbamoylmethyphosphine oxide (CMOP)- 1.2 M Tri-n-butylphosphate (TBP) in room temperature ionic liquid 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]amide ([C4min][NTf2]), and a nitric acid solution of 1M were chosen. These fluids are relevant Eu(III) separation by extraction from nitric acid solutions. The two liquid phases were introduced into microchannels of 0.2 and 0.5mm internal diameter through a T-junction inlet. The flow pattern was visualized during plug formation at the inlet section and further downstream by means by bright field planar micro-Particle Image Velocimetry. Key features of plug flow, such as plug velocity, film thickness, plug length and recirculation intensity were measured under various experimental conditions. To gain further understanding of the 3-D flow field, Computation Fluid Dynamics (CFD) simulations approach were also conducted.

  17. Temper Foam

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Fabricated by Expanded Rubber & Plastics Corporation, Temper Foam provides better impact protection for airplane passengers and enhances passenger comfort on long flights because it distributes body weight and pressure evenly over the entire contact area. Called a "memory foam" it matches the contour of the body pressing against it and returns to its original shape once the pressure is removed. As a shock absorber, a three-inch foam pad has the ability to absorb the impact of a 10-foot fall by an adult. Applications include seat cushioning for transportation vehicles, padding for furniture and a variety of athletic equipment medical applications including wheelchair padding, artificial limb socket lining, finger splint and hand padding for burn patients, special mattresses for the bedridden and dental stools. Production and sales rights are owned by Temper Foam, Inc. Material is manufactured under license by the Dewey and Almy Division of Grace Chemical Corporation. Distributors of the product are Kees Goebel Medical Specialties, Inc. and Alimed, Inc. They sell Temper Foam in bulk to the fabricators who trim it to shapes required by their customers.

  18. Study on Durability and Stability of an Aqueous Electrolyte Solution for Zinc Bromide Hybrid Flow Batteries

    NASA Astrophysics Data System (ADS)

    Kim, Donghyeon; Jeon, Joonhyeon

    2015-01-01

    Zinc-bromine flow battery using aqueous electrolyte has advantages of cost effective and high energy density, but there still remains a problem improving stability and durability of electrolyte materials during long-time cell operation. This paper focuses on providing a homogeneous aqueous solution for durability and stability of zinc bromide electrolyte. For performance experiments of conventional and proposed electrolyte solutions, detailed cyclic voltammetry (CV) measurements (at a scan rate of 20 mV s-1 in the range of -1.5 V~1.5 V) are carried out for 40 cycles and five kinds of electrolytes containing which has one of additives, such as (conventionally) zinc chloride, potassium chloride, (newly) lithium perchlorate, sodium perchlorate and zeolite-Y are compared with the 2.0 M ZnBr2 electrolyte, respectively. Experimental results show that using the proposed three additives provides higher anodic and cathodic peak current density of electrolytes than using other two conventional additives, and can lead to improved chemical reversibility of zinc bromide electrolyte. Especially, the solution of which the zeolite-Y added, shows enhanced electrochemical stability of zinc bromide electrolyte. Consequently, proposed electrolytes have a significant advantage in comparison with conventional electrolytes on higher stability and durability.

  19. High temperature ultralow water content carbon dioxide-in-water foam stabilized with viscoelastic zwitterionic surfactants.

    PubMed

    Alzobaidi, Shehab; Da, Chang; Tran, Vu; Prodanović, Maša; Johnston, Keith P

    2017-02-15

    Ultralow water content carbon dioxide-in-water (C/W) foams with gas phase volume fractions (ϕ) above 0.95 (that is <0.05 water) tend to be inherently unstable given that the large capillary pressures that cause the lamellar films to thin. Herein, we demonstrate that these C/W foams may be stabilized with viscoelastic aqueous phases formed with a single zwitterionic surfactant at a concentration of only 1% (w/v) in DI water and over a wide range of salinity. Moreover, they are stable with a foam quality ϕ up to 0.98 even for temperatures up to 120°C. The properties of aqueous viscoelastic solutions and foams containing these solutions are examined for a series of zwitterionic amidopropylcarbobetaines, R-ONHC3H6N(CH3)2CH2CO2, where R is varied from C12-14 (coco) to C18 (oleyl) to C22 (erucyl). For the surfactants with long C18 and C22 tails, the relaxation times from complex rheology indicate the presence of viscoelastic wormlike micelles over a wide range in salinity and pH, given the high surfactant packing fraction. The apparent viscosities of these ultralow water content foams reached more than 120cP with stabilities more than 30-fold over those for foams formed with the non-viscoelastic C12-14 surfactant. At 90°C, the foam morphology was composed of ∼35μm diameter bubbles with a polyhedral texture. The apparent foam viscosity typically increased with ϕ and then dropped at ϕ values higher than 0.95-0.98. The Ostwald ripening rate was slower for foams with viscoelastic versus non-viscoelastic lamellae as shown by optical microscopy, as a consequence of slower lamellar drainage rates. The ability to achieve high stabilities for ultralow water content C/W foams over a wide temperature range is of interest in various technologies including polymer and materials science, CO2 enhanced oil recovery, CO2 sequestration (by greater control of the CO2 flow patterns), and possibly even hydraulic fracturing with minimal use of water to reduce the requirements for

  20. Aqueous Lithium-Iodine Solar Flow Battery for the Simultaneous Conversion and Storage of Solar Energy.

    PubMed

    Yu, Mingzhe; McCulloch, William D; Beauchamp, Damian R; Huang, Zhongjie; Ren, Xiaodi; Wu, Yiying

    2015-07-08

    Integrating both photoelectric-conversion and energy-storage functions into one device allows for the more efficient solar energy usage. Here we demonstrate the concept of an aqueous lithium-iodine (Li-I) solar flow battery (SFB) by incorporation of a built-in dye-sensitized TiO2 photoelectrode in a Li-I redox flow battery via linkage of an I3(-)/I(-) based catholyte, for the simultaneous conversion and storage of solar energy. During the photoassisted charging process, I(-) ions are photoelectrochemically oxidized to I3(-), harvesting solar energy and storing it as chemical energy. The Li-I SFB can be charged at a voltage of 2.90 V under 1 sun AM 1.5 illumination, which is lower than its discharging voltage of 3.30 V. The charging voltage reduction translates to energy savings of close to 20% compared to conventional Li-I batteries. This concept also serves as a guiding design that can be extended to other metal-redox flow battery systems.

  1. MWCNTs based high sensitive lateral flow strip biosensor for rapid determination of aqueous mercury ions.

    PubMed

    Yao, Li; Teng, Jun; Zhu, Mengya; Zheng, Lei; Zhong, Youhao; Liu, Guodong; Xue, Feng; Chen, Wei

    2016-11-15

    Here, we describe a disposable multi-walled carbon nanotubes (MWCNTs) labeled nucleic acid lateral flow strip biosensor for rapid and sensitive detection of aqueous mercury ions (Hg(2+)). Unlike the conventional colloidal gold nanoparticle based strip biosensors, the carboxylated MWCNTs were selected as the labeling substrate because of its high specific surface area for immobilization of recognition probes, improved stability and enhanced detection sensitivity of the strip biosensor. Combining the sandwich-type of T-Hg(2+)-T recognition mechanism with the optical properties of MWCNTs on lateral flow strip, optical black bands were observed on the lateral flow strips. Parameters (such as membrane category, the MWCNTs concentration, the amount of MWCNT-DNA probe, and the volume of the test probe) that govern the sensitivity and reproducibility of the sensor were optimized. The response of the optimized biosensor was highly linear over the range of 0.05-1ppb target Hg(2+), and the detection threshold was estimated at 0.05 ppb within a 15-min assay time. The sensitivity was 10-fold higher than the conventional colloidal gold based strip biosensor. More importantly, the stability of the sensor was also greatly improved with the usage of MWCNTs as the labeling.

  2. B-Plant canyon fire foam supply

    SciTech Connect

    Gainey, T.

    1995-01-01

    A new raw water supply was installed for the B-Plant fire foam system. This document details tests to be performed which will demonstrate that the system can function as designed. The tests include: Verification of the operation of the automatic valves at the cells; Measurement of water flow and pressure downstream of the proportioner; Production of foam, and measurement of foam concentration. Included as an appendix is a copy of the work package resolution (J4 & J4a).

  3. ZERO-VALENT IRON REMOVAL RATES OF AQUEOUS Cr(VI) MEASURED UNDER FLOW CONDITIONS

    SciTech Connect

    Kaplan, Daniel I.; Gilmore, Tyler J.

    2004-06-01

    The rates of Cr(VI) removal from the aqueous phase by zero-valent iron, Fe(0), was measured under flow conditions. The intent of this work was to generate removal rate coefficients that would be applicable to the Reactive Well Technology, a groundwater remediation technology that replaces the sand in a filter pack of a conventional well with a reactive material, such as Fe(0). Dissolved Cr(VI) concentration, dissolved O2 concentration, and Eh data indicated that Cr(VI) removal from the aqueous phase was mass-transfer limited. All pseudo-first-order regression fits to the data were significant (P≤0.05), however, they did not capture many of the salient aspects of the data, including that the removal rate often decreased as contact time increased. As such, application of these rate coefficients to predict long-term Cr(VI) removal were compromised. The rate coefficients measured under flow conditions were comparable to those measured previously under batch conditions with significantly greater solution:solid ratios. Between the range of 20 and 100 wt-% Fe(0) in the column, there was little measurable change in the reaction kinetics. Thus, it may be possible to include sand into the reactive filter packs in the event it is necessary to increase filter pack porosity or to decrease the accumulation of secondary reaction products that may lead to filter pack plugging. Background water chemistry (0.2 M NaHCO3, distilled water, and a carbonate-dominated groundwater) had only marginal, if any, effects on reaction rate coefficients. The reaction rates measured in this study indicated that an Fe(0) filter pack could be used to lower Cr(VI) concentrations by several orders of magnitude in a once-through mode of operation of the Reactive Well Technology.

  4. Development of an analytical method for trace gold in aqueous solution using polyurethane foam sorbents: kinetic and thermodynamic characteristic of gold(III) sorption.

    PubMed

    Bashammakh, A S; Bahaffi, S O; Al-Shareef, F M; El-Shahawi, M S

    2009-03-01

    The kinetic parameters of gold(III) sorption by unloaded polyurethane foams (PUFs) and PUFs impregnated with some onium cations e.g. tetramethylammonium perchlorate (TMA(+)ClO(4)(-)), tetrabutylammonium iodide (TBA(+)I(-)), and tetraheptylammonium bromide (THA(+)Br(-)), have been determined. The retention steps were found to be fast, reached equilibrium in a few minutes and followed a first-order rate equation with an overall rate constant, k, of 0.0076 and 0.007 min(-1), respectively. The thermodynamic characteristics of gold(III) retention by the unloaded PUFs and THA(+)Br(-) immobilized PUFs have been critically studied. The negative values of DeltaH and DeltaS are interpreted as the exothermic and spontaneous reaction of gold(III) sorption onto unloaded PUFs and foams impregnated with THA(+)Br(-). The cellular structure of the PUFs sorbent offer unique advantages over conventional bulk-type sorbents in the rapid, versatile effective separation and/or preconcentration of gold ions.

  5. Polyimide Foams

    NASA Technical Reports Server (NTRS)

    Vazquez, Juan M. (Inventor); Cano, Roberto J. (Inventor); Jensen, Brian J. (Inventor); Weiser, Erik S. (Inventor)

    2005-01-01

    A fully imidized, solvent-free polyimide foam having excellent mechanical, acoustic, thermal, and flame resistant properties is produced. A first solution is provided, which includes one or more aromatic dianhydrides or derivatives of aromatic dianhydrides, and may include one or more aromatic diamines, dissolved in one or more polar solvents, along with an effective amount of one or more blowing agents. This first solution may also advantageously include effective amounts respectively of one or mores catalysts, one or more surfactants, and one or more fire retardants. A second solution is also provided which includes one or more isocyanates. The first and second solutions are rapidly and thoroughly mixed to produce an admixture, which is allowed to foam-in an open container, or in a closed mold-under ambient conditions to completion produce a foamed product. This foamed product is then cured by high frequency electromagnetic radiation, thermal energy, or a combination thereof. Alternatively, the process is adapted for spraying or extrusion.

  6. Polyimide foams

    NASA Technical Reports Server (NTRS)

    Vazquez, Juan M. (Inventor); Cano, Roberto J. (Inventor); Jensen, Brian J. (Inventor); Weiser, Erik S. (Inventor)

    2005-01-01

    A fully imidized, solvent-free polyimide foam having excellent mechanical, acoustic, thermal, and flame resistant properties is produced. A first solution is provided, which includes one or more aromatic dianhydrides or derivatives of aromatic dianhydrides, and may include one or more aromatic diamines, dissolved in one or more polar solvents, along with an effective amount of one or more blowing agents. This first solution may also advantageously include effective amounts respectively of one or mores catalysts, one or more surfactants, and one or more fire retardants. A second solution is also provided which includes one or more isocyanates. The first and second solutions are rapidly and thoroughly mixed to produce an admixture, which is allowed to foam?in an open container, or in a closed mold?under ambient conditions to completion produce a foamed product. This foamed product is then cured by high frequency electromagnetic radiation, thermal energy, or a combination thereof. Alternatively, the process is adapted for spraying or extrusion.

  7. Polyimide foams

    NASA Technical Reports Server (NTRS)

    Vazquez, Juan M. (Inventor); Cano, Roberto J. (Inventor); Jensen, Brian J. (Inventor); Weiser, Erik S. (Inventor)

    2009-01-01

    A fully imidized, solvent-free polyimide foam having excellent mechanical, acoustic, thermal, and flame resistant properties is produced. A first solution is provided, which includes one or more aromatic dianhydrides or derivatives of aromatic dianhydrides, and may include one or more aromatic diamines, dissolved in one or more polar solvents, along with an effective amount of one or more blowing agents. This first solution may also advantageously include effective amounts respectively of one or mores catalysts, one or more surfactants, and one or more fire retardants. A second solution is also provided which includes one or more isocyanates. The first and second solutions are rapidly and thoroughly mixed to produce an admixture, which is allowed to foam--in an open container, or in a closed mold--under ambient conditions to completion produce a foamed product. This foamed product is then cured by high frequency electromagnetic radiation, thermal energy, or a combination thereof. Alternatively, the process is adapted for spraying or extrusion.

  8. Coalescence of dry foam under water injection.

    PubMed

    Mensire, Rémy; Piroird, Keyvan; Lorenceau, Elise

    2014-09-28

    When a small volume of pure water - typically a drop - is injected within an aqueous foam, it locally triggers the rupture of foam films, thus opening an empty cavity in the foam's bulk. We consider the final shape of this cavity and we quantify its volume as a function of the volume of injected water, the diameter of the bubbles and the liquid fraction of the foam. We provide quantitative understanding to explain how and when this cavity appears. We epitomize the dilution of surfactants at the water-air interfaces as the main cause lying behind the coalescence process. We identify a new coalescence regime for which a critical surfactant concentration rules the stability of the foam.

  9. A continuous flow microfluidic calorimeter: 3-D numerical modeling with aqueous reactants

    PubMed Central

    Sen, Mehmet A.; Kowalski, Gregory J.; Fiering, Jason; Larson, Dale

    2015-01-01

    A computational analysis of the reacting flow field, species diffusion and heat transfer processes with thermal boundary layer effects in a microchannel reactor with a coflow configuration was performed. Two parallel adjacent streams of aqueous reactants flow along a wide, shallow, enclosed channel in contact with a substrate, which is affixed to a temperature controlled plate. The Fluent computational fluid dynamics package solved the Navier–Stokes, mass transport and energy equations. The energy model, including the enthalpy of reaction as a nonuniform heat source, was validated by calculating the energy balance at several control volumes in the microchannel. Analysis reveals that the temperature is nearly uniform across the channel thickness, in the direction normal to the substrate surface; hence, measurements made by sensors at or near the surface are representative of the average temperature. Additionally, modeling the channel with a glass substrate and a silicone cover shows that heat transfer is predominantly due to the glass substrate. Finally, using the numerical results, we suggest that a microcalorimeter could be based on this configuration, and that temperature sensors such as optical nanohole array sensors could have sufficient spatial resolution to determine enthalpy of reaction. PMID:25937678

  10. Removal Rates of Aqueous Cr(VI) by Zero-Valent Iron Measured Under Flow Conditions

    SciTech Connect

    Kaplan, D.I.

    2002-05-10

    Studies were undertaken to measure the rate of Cr(VI) removal from the aqueous phase by zero-valent iron, Fe(0), under flow conditions. The intent of this work was to generate removal rate coefficients that would be applicable to the Reactive Well Technology, a groundwater remediation technology that replaces the sand in a filter pack of a conventional well with a reactive material, such as Fe(0). The pseudo-first-order rate coefficients measured under flow conditions were comparable to those previously measured under batch conditions that had significantly greater ratios of solution volume to Fe(0) surface area. Between the range of 20 and 100 weight percent Fe(0), there was little measurable change in the reaction kinetics. Thus, it may be possible to include sand into the reactive filter packs in the event it is necessary to increase filter pack porosity or to decrease the accumulation of secondary reaction products that may lead to filter pack plugging. Background water chemistry had only marginal effects on reaction rate coefficients. The reaction rates measured in this study indicated that an Fe(0) filter pack could be used to lower Cr(VI) concentrations by several orders of magnitude in a once-through mode of operation of the Reactive Well Technology.

  11. A continuous flow microfluidic calorimeter: 3-D numerical modeling with aqueous reactants.

    PubMed

    Sen, Mehmet A; Kowalski, Gregory J; Fiering, Jason; Larson, Dale

    2015-03-10

    A computational analysis of the reacting flow field, species diffusion and heat transfer processes with thermal boundary layer effects in a microchannel reactor with a coflow configuration was performed. Two parallel adjacent streams of aqueous reactants flow along a wide, shallow, enclosed channel in contact with a substrate, which is affixed to a temperature controlled plate. The Fluent computational fluid dynamics package solved the Navier-Stokes, mass transport and energy equations. The energy model, including the enthalpy of reaction as a nonuniform heat source, was validated by calculating the energy balance at several control volumes in the microchannel. Analysis reveals that the temperature is nearly uniform across the channel thickness, in the direction normal to the substrate surface; hence, measurements made by sensors at or near the surface are representative of the average temperature. Additionally, modeling the channel with a glass substrate and a silicone cover shows that heat transfer is predominantly due to the glass substrate. Finally, using the numerical results, we suggest that a microcalorimeter could be based on this configuration, and that temperature sensors such as optical nanohole array sensors could have sufficient spatial resolution to determine enthalpy of reaction.

  12. All-soluble all-iron aqueous redox-flow battery

    DOE PAGES

    Gong, Ke; Xu, Fei; Grunewald, Jonathan B.; ...

    2016-05-03

    The rapid growth of intermittent renewable energy (e.g., wind and solar) demands low-cost and large-scale energy storage systems for smooth and reliable power output, where redox-flow batteries (RFBs) could find their niche. In this work, we introduce the first all-soluble all-iron RFB based on iron as the same redox-active element but with different coordination chemistries in alkaline aqueous system. The adoption of the same redox-active element largely alleviates the challenging problem of cross-contamination of metal ions in RFBs that use two redox-active elements. An all-soluble all-iron RFB is constructed by combining an iron–triethanolamine redox pair (i.e., [Fe(TEOA)OH]–/[Fe(TEOA)(OH)]2–) and an iron–cyanidemore » redox pair (i.e., Fe(CN)6 3–/Fe(CN)6 4–), creating 1.34 V of formal cell voltage. Furthermore, good performance and stability have been demonstrated, after addressing some challenges, including the crossover of the ligand agent. As exemplified by the all-soluble all-iron flow battery, combining redox pairs of the same redox-active element with different coordination chemistries could extend the spectrum of RFBs.« less

  13. Computational investigations and grid refinement study of 3D transient flow in a cylindrical tank using OpenFOAM

    NASA Astrophysics Data System (ADS)

    Mohd Sakri, F.; Mat Ali, M. S.; Sheikh Salim, S. A. Z.

    2016-10-01

    The study of physic fluid for a liquid draining inside a tank is easily accessible using numerical simulation. However, numerical simulation is expensive when the liquid draining involves the multi-phase problem. Since an accurate numerical simulation can be obtained if a proper method for error estimation is accomplished, this paper provides systematic assessment of error estimation due to grid convergence error using OpenFOAM. OpenFOAM is an open source CFD-toolbox and it is well-known among the researchers and institutions because of its free applications and ready to use. In this study, three types of grid resolution are used: coarse, medium and fine grids. Grid Convergence Index (GCI) is applied to estimate the error due to the grid sensitivity. A monotonic convergence condition is obtained in this study that shows the grid convergence error has been progressively reduced. The fine grid has the GCI value below 1%. The extrapolated value from Richardson Extrapolation is in the range of the GCI obtained.

  14. Method of foaming a liquid metal

    DOEpatents

    Fischer, Albert K.; Johnson, Carl E.

    1980-01-01

    The addition of a small quantity of barium to liquid metal NaK or sodium has been found to promote foam formation and improve bubble retention in the liquid metal. A stable liquid metal foam will provide a more homogeneous liquid metal flow through the channel of a two-phase liquid metal MHD power generator to improve operating efficiency.

  15. Co-doped titanium oxide foam and water disinfection device

    DOEpatents

    Shang, Jian-Ku; Wu, Pinggui; Xie, Rong-Cai

    2016-01-26

    A quaternary oxide foam, comprises an open-cell foam containing (a) a dopant metal, (b) a dopant nonmetal, (c) titanium, and (d) oxygen. The foam has the advantages of a high surface area and a low back pressure during dynamic flow applications. The inactivation of Escherichia coli (E. coli) was demonstrated in a simple photoreactor.

  16. Comparison of the efficacy of betaxolol-brinzolamide and timolol-dorzolamide as suppressors of aqueous humor flow in human subjects.

    PubMed

    Brubaker, R F; Ingram, C J; Schoff, E O; Nau, C B

    2000-02-01

    To compare the efficacy of combinations of betaxolol-brinzolamide and timolol-dorzolamide as suppressors of aqueous humor flow and ocular hypotensive agents. Placebo-controlled, masked comparison of the two drug combinations. Twenty-five normal human volunteers with the fellow eye serving as control. METHODS OR TESTING: Fluorophotometric measurement of aqueous humor flow and pneumatonometric measurement of intraocular pressure. Aqueous humor flow and intraocular pressure. The betaxolol-brinzolamide combination lowered aqueous flow 39% to 44%, and the timololdorzolamide combination lowered aqueous flow 51%. The betaxolol-brinzolamide combination lowered intraocular pressure 14% to 19%, and the timolol-dorzolamide combination lowered it 18% to 24%. Both drug combinations were effective; the timolol-dorzolamide combination appeared to be the more effective of the two after short-term exposure (24 hours).

  17. Effects of inlet boundary conditions, on the computed flow in the Turbine-99 draft tube, using OpenFOAM and CFX

    NASA Astrophysics Data System (ADS)

    Nilsson, H.; Cervantes, M. J.

    2012-11-01

    The flow in the Turbine-99 Kaplan draft tube was thoroughly investigated at three workshops (1999, 2001, 2005), which aimed at determining the state of the art of draft tube simulations. The flow is challenging due to the different flow phenomena appearing simultaneously such as unsteadiness, separation, swirl, turbulence, and a strong adverse pressure gradient. The geometry and the experimentally determined inlet boundary conditions were provided to the Turbine-99 workshop participants. At the final workshop, angular resolved inlet velocity boundary conditions were provided. The rotating non-axi-symmetry of the inlet flow due to the runner blades was thus included. The effect of the rotating angular resolution was however not fully investigated at that workshop. The first purpose of this work is to further investigate this effect. Several different inlet boundary conditions are applied - the angular resolved experimental data distributed at the Turbine-99 workshop, the angular resolved results of a runner simulation with interpolated values using different resolution in the tangential and radial directions, and an axi-symmetric variant of the same numerical data. The second purpose of this work is to compare the results from the OpenFOAM and CFX CFD codes, using as similar settings as possible. The present results suggest that the experimental angular inlet boundary conditions proposed to the workshop are not adequate to simulate accurately the flow in the T-99 draft tube. The reason for this is that the experimental phase-averaged data has some important differences compared to the previously measured time-averaged data. Using the interpolated data from the runner simulation as inlet boundary condition however gives good results as long as the resolution of that data is sufficient. It is shown that the difference between the results using the angular-resolved and the corresponding symmetric inlet data is very small, suggesting that the importance of the angular

  18. Continuous flowing micro-reactor for aqueous reaction at temperature higher than 100 °C

    PubMed Central

    Xie, Fei; Wang, Baojun; Wang, Wei; Dong, Tian; Tong, Jianhua; Xia, Shanhong; Wu, Wengang; Li, Zhihong

    2013-01-01

    Some aqueous reactions in biological or chemical fields are accomplished at a high temperature. When the reaction temperature is higher than 100 °C, an autoclave reactor is usually required to elevate the boiling point of the water by creating a high-pressure environment in a closed system. This work presented an alternative continuous flowing microfluidic solution for aqueous reaction with a reaction temperature higher than 100 °C. The pressure regulating function was successfully fulfilled by a small microchannel based on a delicate hydrodynamic design. Combined with micro heater and temperature sensor that integrated in a single chip by utilizing silicon-based microfabrication techniques, this pressure regulating microchannel generated a high-pressure/high-temperature environment in the upstream reaction zone when the reagents continuously flow through the chip. As a preliminary demonstration, thermal digestion of aqueous total phosphorus sample was achieved in this continuous flowing micro-reactor at a working pressure of 990 kPa (under the working flow rate of 20 nl/s) along with a reaction temperature of 145 °C. This continuous flowing microfluidic solution for high-temperature reaction may find applications in various micro total analysis systems. PMID:24404024

  19. Infiltrated carbon foam composites

    NASA Technical Reports Server (NTRS)

    Lucas, Rick D. (Inventor); Danford, Harry E. (Inventor); Plucinski, Janusz W. (Inventor); Merriman, Douglas J. (Inventor); Blacker, Jesse M. (Inventor)

    2012-01-01

    An infiltrated carbon foam composite and method for making the composite is described. The infiltrated carbon foam composite may include a carbonized carbon aerogel in cells of a carbon foam body and a resin is infiltrated into the carbon foam body filling the cells of the carbon foam body and spaces around the carbonized carbon aerogel. The infiltrated carbon foam composites may be useful for mid-density ablative thermal protection systems.

  20. 2D Numerical Investigation of the Laminar and Turbulent Flow Over Different Airfoils Using OpenFOAM

    NASA Astrophysics Data System (ADS)

    Rahimi, H.; Medjroubi, W.; Stoevesandt, B.; Peinke, J.

    2014-12-01

    The aim of this work is to assess the prediction capabilities of the turbulence models and the transition model kkl-ω available in OpenFOAM and to achieve a database of airfoil aerodynamical characteristics. The airfoils chosen for the simulations are FX 79-W- 15A and NACA 63-430, which are widely used in wind turbines. The numerically obtained lift and drag coefficients are compared with available experimental results. A quantitative and qualitative study is conducted to determine the influence of meshing strategies, computational time step together with interpolation and temporal schemes. Two Reynolds Averaged Navier- Stokes models (RANS models) are used, which are the k-ω SST model by Menter and the kkl-ω model (which involves transition modeling) by Walters and Davor.

  1. Occurrence of select perfluoroalkyl substances at U.S. Air Force aqueous film-forming foam release sites other than fire-training areas: Field-validation of critical fate and transport properties.

    PubMed

    Anderson, R Hunter; Long, G Cornell; Porter, Ronald C; Anderson, Janet K

    2016-05-01

    The use of aqueous film-forming foam (AFFF) to extinguish hydrocarbon-based fires is recognized as a significant source of environmental poly- and perfluoroalkyl substances (PFASs). Although the occurrence of select PFASs in soil and groundwater at former fire-training areas (FTAs) at military installations operable since 1970 has been consistently confirmed, studies reporting the occurrence of PFASs at other AFFF-impacted sites (e.g. emergency response locations, AFFF lagoons, hangar-related AFFF storage tanks and pipelines, and fire station testing and maintenance areas) are largely missing from the literature. Further, studies have mostly focused on a single site (i.e., FTAs at military installations) and, thus, lack a comparison of sites with diverse AFFF release history. Therefore, the purpose of this investigation was to evaluate select PFAS occurrence at non-FTA sites on active U.S. Air Force installations with historic AFFF use of varying magnitude. Concentrations of fifteen perfluoroalkyl acids (PFAAs) and perfluorooctane sulfonamide (PFOSA), an important PFOS precursor, were measured from several hundred samples among multiple media (i.e., surface soil, subsurface soil, sediment, surface water, and groundwater) collected from forty AFFF-impacted sites across ten installations between March and September 2014, representing one of the most comprehensive datasets on environmental PFAS occurrence to date. Differences in detection frequencies and observed concentrations due to AFFF release volume are presented along with rigorous data analyses that quantitatively demonstrate phase-dependent (i.e., solid-phase vs aqueous-phase) differences in the chemical signature as a function of carbon chain-length and in situ PFOS (and to a slightly lesser extent PFHxS) formation, presumably due to precursor biotransformation.

  2. An Aqueous Redox-Flow Battery with High Capacity and Power: The TEMPTMA/MV System.

    PubMed

    Janoschka, Tobias; Martin, Norbert; Hager, Martin D; Schubert, Ulrich S

    2016-11-07

    Redox-flow batteries (RFB) can easily store large amounts of electric energy and thereby mitigate the fluctuating output of renewable power plants. They are widely discussed as energy-storage solutions for wind and solar farms to improve the stability of the electrical grid. Most common RFB concepts are based on strongly acidic metal-salt solutions or poorly performing organics. Herein we present a battery which employs the highly soluble N,N,N-2,2,6,6-heptamethylpiperidinyl oxy-4-ammonium chloride (TEMPTMA) and the viologen derivative N,N'-dimethyl-4,4-bipyridinium dichloride (MV) in a simple and safe aqueous solution as redox-active materials. The resulting battery using these electrolyte solutions has capacities of 54 Ah L(-1) , giving a total energy density of 38 Wh L(-1) at a cell voltage of 1.4 V. With peak current densities of up to 200 mA cm(-2) the TEMPTMA/MV system is a suitable candidate for compact high-capacity and high-power applications.

  3. Continuously Infusing Hyperpolarized 129Xe into Flowing Aqueous Solutions Using Hydrophobic Gas Exchange Membranes

    PubMed Central

    Cleveland, Zackary I.; Möller, Harald E.; Hedlund, Laurence W.; Driehuys, Bastiaan

    2009-01-01

    Hyperpolarized (HP) 129Xe yields high signal intensities in magnetic resonance (MR) and, through its large chemical shift range of ∼300 ppm, provides detailed information about the local chemical environment. To exploit these properties in aqueous solutions and living tissues requires the development of methods for efficiently dissolving HP 129Xe over an extended time period. To this end, we have used commercially available gas exchange modules to continuously infuse concentrated HP 129Xe into flowing liquids, including rat whole blood, for periods as long as one hour, and have demonstrated the feasibility of dissolved-phase MR imaging with sub-millimeter resolution within minutes. These modules, which exchange gases using hydrophobic microporous polymer membranes, are compatible with a variety of liquids and are suitable for infusing HP 129Xe into the bloodstream in vivo. Additionally, we have developed a detailed mathematical model of the infused HP 129Xe signal dynamics that should be useful in designing improved infusion systems that yield even higher dissolved HP 129Xe signal intensities. PMID:19702286

  4. Organic Redox Species in Aqueous Flow Batteries: Redox Potentials, Chemical Stability and Solubility

    PubMed Central

    Wedege, Kristina; Dražević, Emil; Konya, Denes; Bentien, Anders

    2016-01-01

    Organic molecules are currently investigated as redox species for aqueous low-cost redox flow batteries (RFBs). The envisioned features of using organic redox species are low cost and increased flexibility with respect to tailoring redox potential and solubility from molecular engineering of side groups on the organic redox-active species. In this paper 33, mainly quinone-based, compounds are studied experimentially in terms of pH dependent redox potential, solubility and stability, combined with single cell battery RFB tests on selected redox pairs. Data shows that both the solubility and redox potential are determined by the position of the side groups and only to a small extent by the number of side groups. Additionally, the chemical stability and possible degradation mechanisms leading to capacity loss over time are discussed. The main challenge for the development of all-organic RFBs is to identify a redox pair for the positive side with sufficiently high stability and redox potential that enables battery cell potentials above 1 V. PMID:27966605

  5. Organic Redox Species in Aqueous Flow Batteries: Redox Potentials, Chemical Stability and Solubility

    NASA Astrophysics Data System (ADS)

    Wedege, Kristina; Dražević, Emil; Konya, Denes; Bentien, Anders

    2016-12-01

    Organic molecules are currently investigated as redox species for aqueous low-cost redox flow batteries (RFBs). The envisioned features of using organic redox species are low cost and increased flexibility with respect to tailoring redox potential and solubility from molecular engineering of side groups on the organic redox-active species. In this paper 33, mainly quinone-based, compounds are studied experimentially in terms of pH dependent redox potential, solubility and stability, combined with single cell battery RFB tests on selected redox pairs. Data shows that both the solubility and redox potential are determined by the position of the side groups and only to a small extent by the number of side groups. Additionally, the chemical stability and possible degradation mechanisms leading to capacity loss over time are discussed. The main challenge for the development of all-organic RFBs is to identify a redox pair for the positive side with sufficiently high stability and redox potential that enables battery cell potentials above 1 V.

  6. Comparison of bacteria and fungus-binding mesh, foam and gauze as fillers in negative pressure wound therapy--pressure transduction, wound edge contraction, microvascular blood flow and fluid retention.

    PubMed

    Malmsjö, Malin; Ingemansson, Richard; Lindstedt, Sandra; Gustafsson, Lotta

    2013-10-01

    Bacteria- and fungus-binding mesh binds with and inactivates bacteria and fungus, which makes it an interesting alternative, wound filler for negative pressure wound therapy (NPWT). This study was conducted to compare the performance of pathogen-binding mesh, foam and gauze as wound fillers in NPWT with regard to pressure transduction, fluid retention, wound contraction and microvascular blood flow. Wounds on the backs of 16 pigs were filled with pathogen-binding mesh, foam or gauze and treated with NPWT. The immediate effects of 0, -40, -60, -80 and -120 mmHg, on pressure transduction and blood flow were examined in eight pigs using laser Doppler velocimetry. Wound contraction and fluid retention were studied during 72 hours of NPWT at -80 and -120 mmHg in the other eight pigs. Pathogen-binding mesh, gauze and foam provide similar pressure transduction to the wound bed during NPWT. Blood flow was found to decrease 0.5 cm laterally from the wound edge and increase 2.5 cm from the wound edge, but was unaltered 5.0 cm from the wound edge. The increase in blood flow was similar with all wound fillers. The decrease in blood flow was more pronounced with foam than with gauze and pathogen-binding mesh. Similarly, wound contraction was more pronounced with foam, than with gauze and pathogen-binding mesh. Wound fluid retention was the same in foam and pathogen-binding mesh, while more fluid was retained in the wound when using gauze. The blood flow 0.5-5 cm from the wound edge and the contraction of the wound during NPWT were similar when using pathogen-binding mesh and gauze. Wound fluid was efficiently removed when using pathogen-binding mesh, which may explain previous findings that granulation tissue formation is more rapid under pathogen-binding mesh than under gauze. This, in combination with its pathogen-binding properties, makes this mesh an interesting wound filler for use in NPWT. © 2012 The Authors. International Wound Journal © 2012 John Wiley & Sons Ltd and

  7. Quantum Foam

    SciTech Connect

    Lincoln, Don

    2014-10-24

    The laws of quantum mechanics and relativity are quite perplexing however it is when the two theories are merged that things get really confusing. This combined theory predicts that empty space isn’t empty at all – it’s a seething and bubbling cauldron of matter and antimatter particles springing into existence before disappearing back into nothingness. Scientists call this complicated state of affairs “quantum foam.” In this video, Fermilab’s Dr. Don Lincoln discusses this mind-bending idea and sketches some of the experiments that have convinced scientists that this crazy prediction is actually true.

  8. Stable oil-laden foams: Formation and evolution.

    PubMed

    Mensire, Rémy; Lorenceau, Elise

    2017-08-02

    The interaction between oil and foam has been the subject of various studies. Indeed, oil can be an efficient defoaming agent, which can be highly valuable in various industrial applications where undesired foaming may occur, as seen in jet-dyeing processes or waste water treatment plant. However, oil and foam can also constructively interact as observed in detergency, fire-fighting, food and petroleum industries, where oil can be in the foam structure or put into contact with the foam without observing a catastrophic break-up of the foam. Under specific physico-chemistry conditions, the oil phase can even be trapped inside the aqueous network of the foam, thus providing interesting complex materials made of three different fluid phases that we name oil-laden foam (OLF). In this review, we focus on such systems, with a special emphasis on dry OLF, i.e. with a total liquid volume fraction, ε smaller than 5%. We first try to clarify the physical and chemical conditions for these systems to appear, we review the different techniques of the literature to obtain them. Then we discuss their structure and identify two different OLF morphologies, named foamed emulsion, in which small oil globules are comprised within the network of the aqueous foam and biliquid foams, where the oil also comprised in the aqueous foam network is continuous at the scale of several bubbles. Last, we review the state of the art of their evolution in particular concerning topological changes, coalescence, coarsening and drainage. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Foam-based adsorbents having high adsorption capacities for recovering dissolved metals and methods thereof

    DOEpatents

    Janke, Christopher J.; Dai, Sheng; Oyola, Yatsandra

    2015-06-02

    Foam-based adsorbents and a related method of manufacture are provided. The foam-based adsorbents include polymer foam with grafted side chains and an increased surface area per unit weight to increase the adsorption of dissolved metals, for example uranium, from aqueous solutions. A method for forming the foam-based adsorbents includes irradiating polymer foam, grafting with polymerizable reactive monomers, reacting with hydroxylamine, and conditioning with an alkaline solution. Foam-based adsorbents formed according to the present method demonstrated a significantly improved uranium adsorption capacity per unit weight over existing adsorbents.

  10. Flow injection determination of cobalt after its sorption onto polyurethane foam loaded with 2-(2-thiazolylazo)-p-cresol (TAC).

    PubMed

    Cassella, R J; Salim, V A; Jesuíno, L S; Santelli, R E; Ferreira, S L; de Carvalho, M S

    2001-03-30

    This paper reports the development of a new methodology for determination of cobalt in water samples by using a flow injection system with loaded PUF as solid phase to preconcentrate analytes. Procedure is based on on-line retention of Co(III) ions (generated in alkaline medium by Co(II) oxidation) in a minicolumn packed with a polyether type polyurethane foam loaded with TAC (2-(2-thiazolylazo)-p-cresol) and elution with 2 mol l(-1) HCl directly to the flame atomic absorption spectrometer nebulizer. Several chemical and flow variables that could affect the performance of this system were investigated as well as the possible interferents. For 2 min of preconcentration time (10.0 ml of sample volume) the system achieved a detection limit 3.2 mug l(-1), a R.S.D. 5% at 20 mug l(-1) and an analytical throughput 24 h(-1). Whereas for 3 min of preconcentration time (15.0 ml of sample volume) a detection limit 2.4 mug l(-1), a R.S.D. under 8% at 10 mug l(-1) and a sampling frequency 17 h(-1) were reported.

  11. On how hydrogen bonds affect foam stability.

    PubMed

    Stubenrauch, Cosima; Hamann, Martin; Preisig, Natalie; Chauhan, Vinay; Bordes, Romain

    2017-02-08

    Do intermolecular H-bonds between surfactant head groups play a role for foam stability? From the literature on the foam stability of various surfactants with C12 alkyl chains but different head groups a clear picture emerges: stable foams are only generated when hydrogen bonds can form between the head groups, i.e. when the polar head group has a hydrogen bond donor and a proton acceptor. Stable foams can therefore be generated with surfactants having a sugar unit, a glycine, an amine oxide (at pH~5), or a carboxylic acid (at pH~pKa) as polar head group. On the other hand, aqueous foams stabilized with surfactants having oligo(ethylene oxide), phosphine oxide, quaternary ammonium, sulfate, sarcosine, amine oxide (at pH≠5), or carboxylic acid (at pH≠pKa) are not very stable. These observations suggest that hydrogen bonds between neighbouring molecules at the surface enhance foam stability. Formation of hydrogen bonds between surfactant head groups gives rise to a short-range attractive interaction that may restrict the surfactant's mobility while providing a more elastic surfactant layer which can counteract deformations. To support our hypothesis we carried out a systematic foaming study of two types of surfactants, one of them being capable of forming H-bonds and the other one not. Generating foams of all surfactants mentioned above with the same foaming conditions we found that stable foams are obtained when the head group is capable of forming intersurfactant H-bonds. The outcome of this study constitutes a new step towards the implementation of H-bonds in the future design of surfactants.

  12. Dynamic control of gold nanoparticle morphology in a microchannel flow reactor by glucose reduction in aqueous sodium hydroxide solution.

    PubMed

    Ishizaka, Takayuki; Ishigaki, Atsushi; Kawanami, Hajime; Suzuki, Akira; Suzuki, Toshishige M

    2012-02-01

    Continuous flow synthesis of gold nanoparticles was demonstrated using a microchannel reactor with glucose reduction in aqueous alkaline medium. Particle size, morphology, and visual/optical properties of the dispersion liquid were controlled dynamically by tuning of the rate of NaOH addition. Characteristic star-like nanoparticles formed spontaneously as a quasi-stable state, but they changed the morphology to round shape and showed spectral change over time.

  13. Evaluation of transition-sensitive eddy-viscosity turbulence models for separated flow in OpenFOAM

    NASA Astrophysics Data System (ADS)

    Fadhila, H.; Medina, H.; Beechook, A.; Aleksandrova, S.; Benjamin, S.

    2017-07-01

    A recently published transition-sensitive turbulence model, k-kL-ω-υ2 [1], is implemented in the open-source CFD package OpenFOAM, and its performance is evaluated in comparison with k-kL-ω [2] and υ2- f [3] models. On T3A and T3B flat plate cases, the k-kL-ω-υ2 model gives accurate transitional predictions. On a flapped NACA 23012 aerofoil, it is found to give only a small improvement over the k-kL-ω model (under 5% reduction in error for lift coefficient) compared with experimental results obtained at the Coventry University wind tunnel, showing limited effects of the extra transport equation which was added to sensitise the model to rotation and curvature effects. Assessment of fluctuating kinetic energy and the new wall-normal turbulent velocity scale shows overprediction near the wall compared to the υ2- f model which indicates a delayed prediction of separation.

  14. A new analytical approach based on asymmetrical flow field-flow fractionation coupled to ultraviolet spectrometry and light scattering detection for SWCNT aqueous dispersion studies.

    PubMed

    Gigault, Julien; Grassl, Bruno; Lespes, Gaëtane

    2012-02-21

    This work demonstrates the potential of asymmetrical flow field-flow fractionation (A4F) coupled to Ultraviolet spectrometry (UV) and multi-angle light scattering (MALS) for the study of single-walled carbon nanotube (SWCNT) dispersion in aqueous solutions containing a surfactant. The results indicate that this technique is a powerful analytical tool that is able to evaluate SWCNT dispersion states in aqueous media and, more importantly, determine the presence or absence of aggregates, the numbers and sizes of different SWCNT populations and the SWCNT size distribution. Dynamic light scattering was employed to complete and demonstrate the relevance of the data that were obtained via A4F-UV-MALS. Two different anionic surfactants that are used to disperse SWCNTs were then studied. The dispersing powers of the surfactants were experimentally evaluated based on their structural organizations. This study demonstrates that surfactant concentration and sonication energy are key parameters that control the SWCNT dispersion state and SWCNT structural integrity therein.

  15. Simulation of foam displacement in porous media

    SciTech Connect

    Kovscek, A.R.; Patzek, T.W.; Radke, C.J.

    1993-08-01

    Foam is an excellent fluid for achieving mobility control of gas in porous media. Practical application of foams for EOR processes, however requires a predictive model of foam displacement. Further, quantitative information on foam-flow behavior at reservoir flow rates and pressures is required as input to any field-scale modeling. An experimental and mechanistic-modeling study is reported for the transient flow of foam through 1.3 {mu}m{sup 2} (1.3 D) Boise sandstone at backpressures in excess of 5 MPa (700 psi) over a quality range from 0.80 to 0.99. Total superficial velocities range from as little as 0.42 to 2.20 m/day (1.4 ft/day to 7 ft/day). Sequential pressure taps and gamma-ray densitometry measure flow resistance and in-situ liquid saturations, respectively. We garner experimental pressure and saturation profiles in both the transient and steady states. Adoption of a mean-size foam-bubble conservation equation along with the traditional reservoir simulation equations allows mechanistic foam simulation. Since foam mobility depends heavily upon its texture, the bubble population balance is both useful and necessary as the role of foam texture must be incorporated into any model which seeks accurate prediction of flow properties. Our model employs capillary-pressure-dependent kinetic expressions for lamellae generation and coalescence and also a term for trapping of lamellae. Additionally, the effects of surfactant chemical transport are included. We find quantitative agreement between experimental and theoretical saturation and pressure profiles in both the transient and steady states.

  16. Vacuum applications of metal foams

    NASA Technical Reports Server (NTRS)

    Kendall, B. R. F.

    1980-01-01

    Several vacuum applications of copper foams in the density range 2-5% and pore sizes of 0.5-0.7 mm are discussed, such as a foreline hydrocarbon trap in a mechanical vacuum pump, a molecular-flow resistor, a diffuser, and a water injector. Other suggested applications include the use of foam copper in the form of an externally heated plug to remove traces of oxygen from inert gases bled into a vacuum system through a stainless steel line and the use of the porous surface for minimizing release of secondary electrons from electrodes in the path of charged particle beams.

  17. Drainage and Stratification Kinetics of Foam Films

    NASA Astrophysics Data System (ADS)

    Zhang, Yiran; Sharma, Vivek

    2014-03-01

    Baking bread, brewing cappuccino, pouring beer, washing dishes, shaving, shampooing, whipping eggs and blowing bubbles all involve creation of aqueous foam films. Foam lifetime, drainage kinetics and stability are strongly influenced by surfactant type (ionic vs non-ionic), and added proteins, particles or polymers modify typical responses. The rate at which fluid drains out from a foam film, i.e. drainage kinetics, is determined in the last stages primarily by molecular interactions and capillarity. Interestingly, for certain low molecular weight surfactants, colloids and polyelectrolyte-surfactant mixtures, a layered ordering of molecules, micelles or particles inside the foam films leads to a stepwise thinning phenomena called stratification. Though stratification is observed in many confined systems including foam films containing particles or polyelectrolytes, films containing globular proteins seem not to show this behavior. Using a Scheludko-type cell, we experimentally study the drainage and stratification kinetics of horizontal foam films formed by protein-surfactant mixtures, and carefully determine how the presence of proteins influences the hydrodynamics and thermodynamics of foam films.

  18. Efficient Representation of Detailed Foam Waves by Incorporating Projective Space.

    PubMed

    Kim, Jong-Hyun; Lee, Jung; Cha, Sungdeok; Kim, Chang-Hun

    2016-09-14

    We propose an efficient framework to realistically simulate foam effects in which 3D water particles from a base water solver are first projected onto 2D screen space in order to reduce computational complexity of finding foam particles. Because foam effects are often created primarily in fast and complicated water flows, we analyze acceleration and curvature values to identify the areas exhibiting such flow patterns. Identified foam particles are emitted in 3D simulation space, and each foam particle is advected by its classified type based on its velocity, thereby capturing the essential characteristics of foam wave motions (e.g., floating waves or scattering bubbles). In addition, we provide an intuitive and flexible mechanism (e.g., user sketch or image) to customize parameters and control the appearance of foam effects while minimizing the occurrence of popping artifacts. Experiments convincingly demonstrate that the proposed approach is efficient and easy to use while delivering high-quality results.

  19. Cell morphology of extrusion foamed poly(lactic acid) using endothermic chemical foaming agent.

    PubMed

    Matuana, Laurent M; Faruk, Omar; Diaz, Carlos A

    2009-12-01

    Poly(lactic acid) (PLA) was foamed with an endothermic chemical foaming agent (CFA) through an extrusion process. The effects of polymer melt flow index, CFA content, and processing speed on the cellular structures, void fraction, and cell-population density of foamed PLA were investigated. The apparent melt viscosity of PLA was measured to understand the effect of melt index on the cell morphology of foamed PLA samples. The void fraction was strongly dependent on the PLA melt index. It increased with increasing melt index, reaching a maximum value, after which it decreased. Melt index showed no significant effect on the cell-population density of foamed samples within the narrow range studied. A gas containment limit was observed in PLA foamed with CFA. Both the void fraction and cell-population density increased with an initial increase in CFA content, reached a maximum value, and then decreased as CFA content continued to increase. The processing speed also affected the morphology of PLA foams. The void fraction reached a maximum value as the extruder's screw speed increased to 40 rpm and a further increase in the processing speed tended to reduce the void fraction of foamed samples. By contrast, cell-population density increased one order of magnitude by increasing the screw speed from 20 to 120 rpm. The experimental results indicate that a homogeneous and finer cellular morphology could be successfully achieved in PLA foamed in an extrusion process with a proper combination of polymer melt flow index, CFA content, and processing speed.

  20. Long-Cycling Aqueous Organic Redox Flow Battery (AORFB) toward Sustainable and Safe Energy Storage.

    PubMed

    Hu, Bo; DeBruler, Camden; Rhodes, Zayn; Liu, T Leo

    2017-01-25

    Redox flow batteries (RFBs) are a viable technology to store renewable energy in the form of electricity that can be supplied to electricity grids. However, widespread implementation of traditional RFBs, such as vanadium and Zn-Br2 RFBs, is limited due to a number of challenges related to materials, including low abundance and high costs of redox-active metals, expensive separators, active material crossover, and corrosive and hazardous electrolytes. To address these challenges, we demonstrate a neutral aqueous organic redox flow battery (AORFB) technology utilizing a newly designed cathode electrolyte containing a highly water-soluble ferrocene molecule. Specifically, water-soluble (ferrocenylmethyl)trimethylammonium chloride (FcNCl, 4.0 M in H2O, 107.2 Ah/L, and 3.0 M in 2.0 NaCl, 80.4 Ah/L) and N(1)-ferrocenylmethyl-N(1),N(1),N(2),N(2),N(2)-pentamethylpropane-1,2-diaminium dibromide, (FcN2Br2, 3.1 M in H2O, 83.1 Ah/L, and 2.0 M in 2.0 M NaCl, 53.5 Ah/L) were synthesized through structural decoration of hydrophobic ferrocene with synergetic hydrophilic functionalities including an ammonium cation group and a halide anion. When paired with methyl viologen (MV) as an anolyte, resulting FcNCl/MV and FcN2Br2/MV AORFBs were operated in noncorrosive neutral NaCl supporting electrolytes using a low-cost anion-exchange membrane. These ferrocene/MV AORFBs are characterized as having high theoretical energy density (45.5 Wh/L) and excellent cycling performance from 40 to 100 mA/cm(2). Notably, the FcNCl/MV AORFBs (demonstrated at 7.0 and 9.9 Wh/L) exhibited unprecedented long cycling performance, 700 cycles at 60 mA/cm(2) with 99.99% capacity retention per cycle, and delivered power density up to 125 mW/cm(2). These AORFBs are built from earth-abundant elements and are environmentally benign, thus representing a promising choice for sustainable and safe energy storage.

  1. Surfactant recovery from water using foam fractionation

    SciTech Connect

    Tharapiwattananon, N.; Osuwan, S.; Scamehorn, J.F.

    1996-05-01

    The purpose of this study was to investigate the use of foam fractionation to recover surfactant from water. A simple continuous mode foam fractionation was used and three surfactants were studied (two anionic and one cationic). The effects of air flow rate, foam height, liquid height, liquid feed surfactant concentration, and sparger porosity were studied. This technique was shown to be effective in either surfactant recovery or the reduction of surfactant concentration in water to acceptable levels. As an example of the effectiveness of this technique, the cetylpyridinium chloride concentration in water can be reduced by 90% in one stage with a liquid residence time of 375 minutes. The surfactant concentration in the collapsed foam is 21.5 times the feed concentration. This cationic surfactant was easier to remove from water by foam fractionation than the anionic surfactants studied.

  2. Quantum Foam

    ScienceCinema

    Lincoln, Don

    2016-07-12

    The laws of quantum mechanics and relativity are quite perplexing however it is when the two theories are merged that things get really confusing. This combined theory predicts that empty space isn’t empty at all – it’s a seething and bubbling cauldron of matter and antimatter particles springing into existence before disappearing back into nothingness. Scientists call this complicated state of affairs “quantum foam.” In this video, Fermilab’s Dr. Don Lincoln discusses this mind-bending idea and sketches some of the experiments that have convinced scientists that this crazy prediction is actually true.

  3. Coalescence In Draining Foams Made of Very Small Bubbles.

    PubMed

    Briceño-Ahumada, Zenaida; Drenckhan, Wiebke; Langevin, Dominique

    2016-03-25

    We studied the stability of foams containing small bubbles (radius ≲ 50  μm). The foams are made from aqueous surfactant solutions containing various amounts of glycerol. The foams start breaking at their top, when the liquid volume fraction has decreased sufficiently during liquid drainage. Unlike in foams with larger bubbles, the liquid fraction at which the foam destabilizes is surprisingly high. In order to interpret this observation we propose that film rupture occurs during reorganization events (T1) induced by bubble coarsening, which is particularly rapid in the case of small bubbles. New films are therefore formed rapidly and if their thickness is too small, they cannot be sufficiently covered by surfactant and they break. Using literature data for the duration of T1 events and the thickness of the new films, we show that this mechanism is consistent with the behavior of the foams studied.

  4. Microstructural effects in foam fracture

    NASA Astrophysics Data System (ADS)

    Stewart, Peter; Davis, Stephen; Hilgenfeldt, Sascha

    2015-11-01

    We examine the fracture of a quasi two-dimensional aqueous foam under an applied driving pressure, using a network modelling approach developed for metallic foams by Stewart & Davis (J. Rheol., vol. 56, 2012, p. 543). In agreement with experiments, we observe two distinct mechanisms of failure analogous to those observed in a crystalline solid: a slow ductile mode when the driving pressure is applied slowly, where the void propagates as bubbles interchange neighbours through the T1 process, and a rapid brittle mode for faster application of pressures, where the void advances by successive rupture of liquid films driven by Rayleigh-Taylor instability. The simulations allow detailed insight into the mechanics of the fracturing medium and the role of its microstructure. In particular, we examine the stress distribution around the crack tip and investigate how brittle fracture localizes into a single line of breakages. We also confirm that pre-existing microstructural defects can alter the course of fracture.

  5. Rupture mechanism and interface separation in foam rubber models of earthquakes: a possible solution to the heat flow paradox and the paradox of large overthrusts

    NASA Astrophysics Data System (ADS)

    Brune, James N.; Brown, Stephen; Johnson, Peggy A.

    1993-02-01

    Spontaneous stick-slip along the interface between stressed foam rubber blocks is a simple analog of earthquake rupture and stick-slip. Results from this model are used to elucidate the role of normal stress variations along the interface in the stick-slip process. Observations indicate significant normal interface vibrations and separation during slip, suggesting that dynamic changes in normal stress (rather than a drop in the coefficient of friction) may control stick-slip, as suggested, for example, by Tolstoi, Oden and Martins and Brune and co-workers. Observations of particle trajectories indicate that stick-slip shear motion is associated with various degrees of fault separation. For an asymmetric model, the motion is consistent with slipping motion of the type suggested by Schallamach and Price. For a symmetric model, the motion is similar to that suggested by Comninou and Dundurs. If interface waves of this type, involving separation during slip, occur in earthquakes, they may be a solution to the heat flow paradox, since a major part of the slip occurs during separation and during low normal stress. Thus frictional heat generation is reduced. Normal interface vibrations during stick-slip may explain the high corner frequency of P wave spectra and the generally high levels of P wave spectra beyond the corner frequency. Schallamach-Comninou type waves are consistent with the partial stress drop-abrupt locking-self healing models of Brune and Heaton.

  6. Pitch based foam with particulate

    SciTech Connect

    Klett, James W.

    2001-01-01

    A thermally conductive, pitch based foam composite having a particulate content. The particulate alters the mechanical characteristics of the foam without severely degrading the foam thermal conductivity. The composite is formed by mixing the particulate with pitch prior to foaming.

  7. A subtractive approach to molecular engineering of dimethoxybenzene-based redox materials for non-aqueous flow batteries

    SciTech Connect

    Huang, Jinhua; Su, Liang; Kowalski, Jeffrey A; Barton, John L.; Ferrandon, Magali; Burrell, Anthony K.; Brushett, Fikile R.; Zhang, Lu

    2015-01-01

    The development of new high capacity redox active materials is key to realizing the potential of non-aqueous redox flow batteries (RFBs). In this paper, a series of substituted 1,4- dimethoxybenzenes based redox active molecules, have been developed via a subtractive design approach. Five molecules have been proposed and developed by removing or reducing the bulky substituent groups of DBBB (2,5-di-tert-butyl-1,4- bis(2-methoxyethoxy)benzene), a successful overcharge protection material for lithium-ion batteries. Of these derivatives, 2,3-dimethyl-1,4-dimethoxybenzene (23DDB) and 2,5-dimethyl-1,4-dimethoxybenzene (25DDB) are particularly promising as they demonstrate favorable electrochemical characteristics at gravimetric capacities (161 mAh/g) that approach the stability limit of chemically reversible dimethoxybenzene based structures. Diffusivity, solubility, and galvanostatic cycling results indicate that both 23DDB and 25DDB molecules have promise for non-aqueous RFBs.

  8. Determination of aqueous ozone for potable water treatment applications by chemiluminescence flow-injection analysis. A feasibility study.

    PubMed

    Chung, H K; Bellamy, H S; Dasgupta, P K

    1992-06-01

    The feasibility of determining aqueous ozone by chemiluminescence flow-injection analysis (CL-FIA) was studied for applications in potable water treatment. The ozonated water sample is injected into a pure water carrier and mixed with a dye reagent in front of a photodetector. Many reagents undergo fast CL reactions with aqueous ozone. Most of these reactions display considerable selectivity for ozone over other oxidants of importance in water treatment. Even when there is steady-state response to another oxidant, significant discrimination against the interferents is possible by taking advantage of the much faster kinetics of the CL reaction with ozone. A simple design of a Siemens-type ozone generator and preparation of standard ozone solutions are also described.

  9. Foam granulation: new developments in pharmaceutical solid oral dosage forms using twin screw extrusion machinery.

    PubMed

    Thompson, M R; Weatherley, S; Pukadyil, R N; Sheskey, P J

    2012-07-01

    This paper investigates foam granulation in a twin screw extruder as a new continuous wet granulation technique for pharmaceutical powder drug formulations. Foamed aqueous binder has a reportedly lower soak-to-spread ratio than drop or spray liquid addition in batch granulation. This work demonstrates a twin screw extruder configuration for foam granulation and subsequently compares the new approach against liquid injection in the granulation of α-lactose monohydrate with a methylcellulose binder. Trials were conducted at high powder output rates (20-40 kg/h) and high screw speeds (220-320 RPM) with two screw configurations. Process stability improved with the new technique allowing granulation with less binder. The extruded mass maintained a low exit temperature, being insensitive to operating conditions unlike the liquid injection approach, where temperatures rose significantly as flow rate increased. The particle size distribution by foam granulation reflected a more uniformly wetted mass with larger granule growth noted even for conditions where dry powder exited by liquid injection. Other factors were found similar between the two binder delivery methods such as consumed mechanical energy, as well as fracture strength and compressibility of produced granules.

  10. The consequences of air flow on the distribution of aqueous species during dielectric barrier discharge treatment of thin water layers

    NASA Astrophysics Data System (ADS)

    Tian, Wei; Lietz, Amanda M.; Kushner, Mark J.

    2016-10-01

    The desired outcomes of wet tissue treatment by dielectric barrier discharges (DBDs) strongly depend on the integrated fluences of reactive species incident onto the tissue, which are determined by power, frequency and treatment time. The reactivity produced by such plasmas is often expected to be proportional to treatment time due to the accumulation of radicals in the liquid over the tissue. However, one of the typically uncontrolled parameters in DBD treatment of liquids and tissue is gas flow, which could affect the delivery of plasma produced radicals to the tissue. Gas flow can redistribute long-lived, plasma produced gas phase species prior to solvating in the liquid, while not greatly affecting the solvation of short-lived species. Gas flow can therefore potentially be a control mechanism for tailoring the fluences of reactive species to the tissue. In this paper, we report on a computational investigation of the consequences of gas flow on treatment of liquid layers covering tissue by atmospheric DBDs by up to 100 pulses. We found that gas flow (through residence time of the gas) can control the production of gas phase species requiring many collisions to form, such as reactive nitrogen species (RNS). The resulting solvation of the RNS in turn controls the production of aqueous species such as \\text{NO}\\text{3aq}- and \\text{ONOO}\\text{aq}- (aq denotes an aqueous species). With the exception of O3 and O3aq, reactive oxygen species (ROS) are less sensitive to gas flow, and so OHaq and H2O2aq, are determined primarily by discharge properties.

  11. Wall effects in Stokes experiment with a liquid foam

    NASA Astrophysics Data System (ADS)

    Gao, Haijing; Subramani, Hariprasad; Harris, Michael; Basaran, Osman

    2011-11-01

    Liquid foams are widely used in numerous applications ranging from the oil and gas industry to beauty, healthcare, and household products industries. A fundamental understanding of the relationships between the properties of liquid foams and their flow responses is, however, still in its infancy compared to that involving the fluid dynamics of simple fluids. In this talk, the flow of a dry liquid foam around a spherical bead, i.e. the Stokes problem for liquid foams, is studied experimentally. In contrast to previous work (cf. Cantat 2006), the focus of the present research is to probe the effect of a solid wall that is located a few bubble radii from the bead. The new experimental results show that the elastic modulus of dry liquid foams is directly proportional to the surface tension of the foaming agents and inversely proportional to the average bubble size in the foams, in agreement with previous theoretical and experimental studies. The experiments further show that the close proximity of the solid wall causes profound structural changes to the gas bubbles as the foam flows past the bead. A good understanding of these structural changes and how they can affect the elastic modulus of foams can be indispensable in formulating improved models for accurately describing the dynamical response of foams within the realm of continuum mechanics.

  12. Macro-mechanical modeling of blast-wave mitigation in foams. Part II: reliability of pressure measurements

    NASA Astrophysics Data System (ADS)

    Britan, A.; Liverts, M.; Shapiro, H.; Ben-Dor, G.

    2013-02-01

    A phenomenological study of the process occurring when a plane shock wave reflected off an aqueous foam column filling the test section of a vertical shock tube has been undertaken. The experiments were conducted with initial shock wave Mach numbers in the range 1.25le {M}_s le 1.7 and foam column heights in the range 100-450 mm. Miniature piezotrone circuit electronic pressure transducers were used to record the pressure histories upstream and alongside the foam column. The aim of these experiments was to find a simple way to eliminate a spatial averaging as an artifact of the pressure history recorded by the side-on transducer. For this purpose, we discuss first the common behaviors of the pressure traces in extended time scales. These observations evidently quantify the low frequency variations of the pressure field within the different flow domains of the shock tube. Thereafter, we focus on the fronts of the pressure signals, which, in turn, characterize the high-frequency response of the foam column to the shock wave impact. Since the front shape and the amplitude of the pressure signal most likely play a significant role in the foam destruction, phase changes and/or other physical factors, such as high capacity, viscosity, etc., the common practice of the data processing is revised and discussed in detail. Generally, side-on pressure measurements must be used with great caution when performed in wet aqueous foams, because the low sound speed is especially prone to this effect. Since the spatial averaged recorded pressure signals do not reproduce well the real behaviors of the pressure rise, the recorded shape of the shock wave front in the foam appears much thicker. It is also found that when a thin liquid film wet the sensing membrane, the transducer sensitivity was changed. As a result, the pressure recorded in the foam could exceed the real amplitude of the post-shock wave flow. A simple procedure, which allows correcting this imperfection, is discussed in

  13. Asymmetric Flow Field Flow Fractionation of Aqueous C60 Nanoparticles with Size Determination by Dynamic Light Scattering and Quantification by Liquid Chromatography Atmospheric Pressure Photo-Ionization Mass Spectrometry

    EPA Science Inventory

    A size separation method was developed for aqueous C60 fullerene aggregates (aqu/C60) using asymmetric flow field flow fractionation (AF4) coupled to a dynamic light scattering detector in flow through mode. Surfactants, which are commonly used in AF4, were avoided as they may al...

  14. Asymmetric Flow Field Flow Fractionation of Aqueous C60 Nanoparticles with Size Determination by Dynamic Light Scattering and Quantification by Liquid Chromatography Atmospheric Pressure Photo-Ionization Mass Spectrometry

    EPA Science Inventory

    A size separation method was developed for aqueous C60 fullerene aggregates (aqu/C60) using asymmetric flow field flow fractionation (AF4) coupled to a dynamic light scattering detector in flow through mode. Surfactants, which are commonly used in AF4, were avoided as they may al...

  15. Foam film permeability: theory and experiment.

    PubMed

    Farajzadeh, R; Krastev, R; Zitha, Pacelli L J

    2008-02-28

    The mass transfer of gas through foam films is a prototype of various industrial and biological processes. The aim of this paper is to give a perspective and critical overview of studies carried out to date on the mass transfer of gas through foam films. Contemporary experimental data are summarized, and a comprehensive overview of the theoretical models used to explain the observed effects is given. A detailed description of the processes that occur when a gas molecule passes through each layer that forms a foam film is shown. The permeability of the film-building surfactant monolayers plays an important role for the whole permeability process. It can be successfully described by the models used to explain the permeability of surfactant monolayers on aqueous sub-phase. For this reason, the present paper briefly discusses the surfactant-induced resistance to mass transfer of gases through gas-liquid interface. One part of the paper discusses the experimental and theoretical aspects of the foam film permeability in a train of foam films in a matrix or a cylinder. This special case is important to explain the gas transfer in porous media or in foams. Finally, this paper will highlight the gaps and challenges and sketch possible directions for future research.

  16. Polyurethane-Foam Maskant

    NASA Technical Reports Server (NTRS)

    Bodemeijer, R.

    1985-01-01

    Brown wax previously used to mask hardware replaced with polyurethane foam in electroplating and electroforming operations. Foam easier to apply and remove than wax and does not contaminate electrolytes.

  17. Fire retardant polyisocyanurate foam

    NASA Technical Reports Server (NTRS)

    Riccitiello, S. R.; Parker, J. A.

    1972-01-01

    Fire retardant properties of low density polymer foam are increased. Foam has pendant nitrile groups which form thermally-stable heterocyclic structures at temperature below degradation temperature of urethane linkages.

  18. Fuel Stability Foam

    DTIC Science & Technology

    1988-08-01

    rupture 1161. Foams containing either polyether or polyester polyols are fuel-compatible, but the polyether variety is considerably less susceptible to...General details of the foams are given in Table 2. Foams containing polyether and polyester polyols , either with reticulated on non- 3 - reticulated...mainly for fuel slosh attenuation, and explosion suppression properties [161. Foams containing either polyether or polyester polyols can be fuel

  19. Controlling Stability and Rheology of Organic Foams

    NASA Astrophysics Data System (ADS)

    Kropka, Jamie; Celina, Mathew

    2009-03-01

    It is often important to understand the stability and flow properties of polymeric foams in order to optimize industrial processing conditions or design new materials. The fact that foaming, polymerization and temperature rise are often coupled in these systems makes it difficult to even characterize existing materials, much less model behaviors to optimize formulations and processing conditions. To make progress in this area, we have developed model foaming systems that decouple these processes and allow us to characterize the physical properties of liquid foams. We are specifically interested in understanding the controlling factors of foam persistence, shear stability, and rheological behavior. We show both chemical (e.g., partial polymerization) and physical (e.g., particulate additives) means of tuning foam persistence as well as both small strain deformation flow and the less understood liquid-like flow at high applied stresses. Sandia is a multi-program laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under Contract DE-AC04-94AL85000.

  20. Enhanced in situ bioremediation using foams and oil aphrons

    SciTech Connect

    Enzien, M.V.; Peters, R.W.; Bouillard, J.X.; Frank, J.R.; Michelsen, D.L.

    1995-12-31

    The use of foams and oil-core aphrons (OCAs) to extract, mobilize, and disperse nonaqueous-phase liquid (NAPL) contaminants for increased bioavailability was investigated. Soil column experiments were used to evaluate foam and OCA flow characteristics in soils. Comparison of pressure drops in soil columns with water, surfactant solution foams and OCAs indicated that foams have the largest pressure drops. Pressure drops with water, surfactant solutions, and OCAs were all comparable. The scouring efficiency of NAPL pools with foams indicated >90% removal, while surfactant solutions removed <10%. OCAs were ineffective at removing contaminants from soils in their experiments. A flat plate visualization cell was used to observe foam flow patterns through porous media. Flow experiments with this cell indicated that (1) foams flow through porous media as a front, whereas surfactant solutions tend to channel; (2) foams can encapsulate low permeability lenses; and (3) foam front advancement increases when vacuum extraction is applied to the outlet. These observations have important implications for potential field-design scenarios.

  1. Metallized polymeric foam material

    NASA Technical Reports Server (NTRS)

    Birnbaum, B. A.; Bilow, N.

    1974-01-01

    Open-celled polyurethane foams can be coated uniformly with thin film of metal by vapor deposition of aluminum or by sensitization of foam followed by electroless deposition of nickel or copper. Foam can be further processed to increase thickness of metal overcoat to impart rigidity or to provide inert surface with only modest increase in weight.

  2. Viscoelastic foam cushion

    NASA Technical Reports Server (NTRS)

    Kubokawa, C. C.; Yost, C.

    1977-01-01

    Foam is viscous and elastic with unusual and useful temperature, humidity, and compression responses. Applied weight and pressure distributed equally along entire interface with foam eliminates any pressure points. Flexible urethane foam is ideal for orthopedic and prosthetic devices, sports equipment, furniture, and crash protection.

  3. Silica Foams for Fire Prevention and Firefighting.

    PubMed

    Vinogradov, Alexander V; Kuprin, D S; Abduragimov, I M; Kuprin, G N; Serebriyakov, Evgeniy; Vinogradov, Vladimir V

    2016-01-13

    We report the new development of fire-extinguishing agents employing the latest technology of fighting and preventing fires. The in situ technology of fighting fires and explosions involves using large-scale ultrafast-gelated foams, which possess new properties and unique characteristics, in particular, exceptional thermal stability, mechanical durability, and full biocompatibility. We provide a detailed description of the physicochemical processes of silica foam formation at the molecular level and functional comparison with current fire-extinguishing and fire-fighting agents. The new method allows to produce controllable gelation silica hybrid foams in the range from 2 to 30 s up to 100 Pa·s viscosity. Chemical structure and hierarchical morphology obtained by scanning electron microscopy and transmission electron microscopy images develop thermal insulation capabilities of the foams, reaching a specific heat value of more than 2.5 kJ/(kg·°C). The produced foam consists of organized silica nanoparticles as determined by X-ray photoelectron spectroscopy and X-ray diffraction analysis with a narrow particle size distribution of ∼10-20 nm. As a result of fire-extinguishing tests, it is shown that the extinguishing efficiency exhibited by silica-based sol-gel foams is almost 50 times higher than that for ordinary water and 15 times better than that for state-of-the-art firefighting agent aqueous film forming foam. The biodegradation index determined by the time of the induction period was only 3 d, while even for conventional foaming agents this index is several times higher.

  4. Aqueous Iron-Sulfide Clusters in Variably Saturated Soil Systems: Implications for Iron Cycling and Fluid Flow

    NASA Astrophysics Data System (ADS)

    McGuire, J. T.; Hansen, D. J.; Mohanty, B. P.

    2008-12-01

    Iron and sulfur cycling is an important control on contaminant fate and transport, the availability of micronutrients and the physics of water flow. This study explores the effects of soil structure (i.e. layers, lenses, macropores, or fractures) on linked biogeochemical and hydrological processes involving Fe and S cycling in the vadose zone using packed soil columns. Three laboratory soil columns were constructed: a homogenized medium-grained sand, homogenized organic-rich loam, and a sand-over-loam layered column. Both upward and downward infiltration of water was evaluated during experiments to simulate rising water table and rainfall events respectively. Water samples extracted by lysimeter were analyzed for reduced species (including total sulfide, Fe(II), and FeSaq) voltammetrically using a mercury drop electrode. In addition to other reduced species, aqueous FeS clusters (FeSaq) were observed in two of the columns, with the greatest concentrations of FeSaq occurring in close proximity to the soil interface in the layered column. To our knowledge, this is the first documentation of aqueous FeS clusters in partially saturated sediments. The aqueous nature of FeSaq allows it to be transported instead of precipitating and suggests that current conceptual models of iron-sulfur cycling may need to be adapted to account for an aqueous phase. The presence of iron-rich soil aggregates near the soil interface may indicate that FeS clusters played a critical role in the formation of soil aggregates that subsequently caused up to an order of magnitude decrease in hydraulic conductivity.

  5. Direct Solar Charging of an Organic–Inorganic, Stable, and Aqueous Alkaline Redox Flow Battery with a Hematite Photoanode

    PubMed Central

    Wedege, Kristina; Azevedo, João; Khataee, Amirreza

    2016-01-01

    Abstract The intermittent nature of the sunlight and its increasing contribution to electricity generation is fostering the energy storage research. Direct solar charging of an auspicious type of redox flow battery could make solar energy directly and efficiently dispatchable. The first solar aqueous alkaline redox flow battery using low cost and environmentally safe materials is demonstrated. The electrolytes consist of the redox couples ferrocyanide and anthraquinone‐2,7‐disulphonate in sodium hydroxide solution, yielding a standard cell potential of 0.74 V. Photovoltage enhancement strategies are demonstrated for the ferrocyanide‐hematite junction by employing an annealing treatment and growing a layer of a conductive polyaniline polymer on the electrode surface, which decreases electron–hole recombination. PMID:27151516

  6. Earth-like aqueous debris-flow activity on Mars at high orbital obliquity in the last million years

    PubMed Central

    de Haas, T.; Hauber, E.; Conway, S. J.; van Steijn, H.; Johnsson, A.; Kleinhans, M. G.

    2015-01-01

    Liquid water is currently extremely rare on Mars, but was more abundant during periods of high obliquity in the last few millions of years. This is testified by the widespread occurrence of mid-latitude gullies: small catchment-fan systems. However, there are no direct estimates of the amount and frequency of liquid water generation during these periods. Here we determine debris-flow size, frequency and associated water volumes in Istok crater, and show that debris flows occurred at Earth-like frequencies during high-obliquity periods in the last million years on Mars. Results further imply that local accumulations of snow/ice within gullies were much more voluminous than currently predicted; melting must have yielded centimetres of liquid water in catchments; and recent aqueous activity in some mid-latitude craters was much more frequent than previously anticipated. PMID:26102485

  7. Earth-like aqueous debris-flow activity on Mars at high orbital obliquity in the last million years.

    PubMed

    de Haas, T; Hauber, E; Conway, S J; van Steijn, H; Johnsson, A; Kleinhans, M G

    2015-06-23

    Liquid water is currently extremely rare on Mars, but was more abundant during periods of high obliquity in the last few millions of years. This is testified by the widespread occurrence of mid-latitude gullies: small catchment-fan systems. However, there are no direct estimates of the amount and frequency of liquid water generation during these periods. Here we determine debris-flow size, frequency and associated water volumes in Istok crater, and show that debris flows occurred at Earth-like frequencies during high-obliquity periods in the last million years on Mars. Results further imply that local accumulations of snow/ice within gullies were much more voluminous than currently predicted; melting must have yielded centimetres of liquid water in catchments; and recent aqueous activity in some mid-latitude craters was much more frequent than previously anticipated.

  8. Direct Solar Charging of an Organic-Inorganic, Stable, and Aqueous Alkaline Redox Flow Battery with a Hematite Photoanode.

    PubMed

    Wedege, Kristina; Azevedo, João; Khataee, Amirreza; Bentien, Anders; Mendes, Adélio

    2016-06-13

    The intermittent nature of the sunlight and its increasing contribution to electricity generation is fostering the energy storage research. Direct solar charging of an auspicious type of redox flow battery could make solar energy directly and efficiently dispatchable. The first solar aqueous alkaline redox flow battery using low cost and environmentally safe materials is demonstrated. The electrolytes consist of the redox couples ferrocyanide and anthraquinone-2,7-disulphonate in sodium hydroxide solution, yielding a standard cell potential of 0.74 V. Photovoltage enhancement strategies are demonstrated for the ferrocyanide-hematite junction by employing an annealing treatment and growing a layer of a conductive polyaniline polymer on the electrode surface, which decreases electron-hole recombination. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Macromolecular Design Strategies for Preventing Active-Material Crossover in Non-Aqueous All-Organic Redox-Flow Batteries.

    PubMed

    Doris, Sean E; Ward, Ashleigh L; Baskin, Artem; Frischmann, Peter D; Gavvalapalli, Nagarjuna; Chénard, Etienne; Sevov, Christo S; Prendergast, David; Moore, Jeffrey S; Helms, Brett A

    2017-02-01

    Intermittent energy sources, including solar and wind, require scalable, low-cost, multi-hour energy storage solutions in order to be effectively incorporated into the grid. All-Organic non-aqueous redox-flow batteries offer a solution, but suffer from rapid capacity fade and low Coulombic efficiency due to the high permeability of redox-active species across the battery's membrane. Here we show that active-species crossover is arrested by scaling the membrane's pore size to molecular dimensions and in turn increasing the size of the active material above the membrane's pore-size exclusion limit. When oligomeric redox-active organics (RAOs) were paired with microporous polymer membranes, the rate of active-material crossover was reduced more than 9000-fold compared to traditional separators at minimal cost to ionic conductivity. This corresponds to an absolute rate of RAO crossover of less than 3 μmol cm(-2)  day(-1) (for a 1.0 m concentration gradient), which exceeds performance targets recently set forth by the battery industry. This strategy was generalizable to both high and low-potential RAOs in a variety of non-aqueous electrolytes, highlighting the versatility of macromolecular design in implementing next-generation redox-flow batteries.

  10. Macromolecular Design Strategies for Preventing Active-Material Crossover in Non-Aqueous All-Organic Redox-Flow Batteries

    DOE PAGES

    Doris, Sean E.; Ward, Ashleigh L.; Baskin, Artem; ...

    2017-01-10

    Intermittent energy sources, including solar and wind, require scalable, low-cost, multi-hour energy storage solutions in order to be effectively incorporated into the grid. All-Organic non-aqueous redox-flow batteries offer a solution, but suffer from rapid capacity fade and low Coulombic efficiency due to the high permeability of redox-active species across the battery's membrane. In this paper, we show that active-species crossover is arrested by scaling the membrane's pore size to molecular dimensions and in turn increasing the size of the active material above the membrane's pore-size exclusion limit. When oligomeric redox-active organics (RAOs) were paired with microporous polymer membranes, the ratemore » of active-material crossover was reduced more than 9000-fold compared to traditional separators at minimal cost to ionic conductivity. This corresponds to an absolute rate of RAO crossover of less than 3 μmol cm-2 day-1 (for a 1.0 m concentration gradient), which exceeds performance targets recently set forth by the battery industry. Finally, this strategy was generalizable to both high and low-potential RAOs in a variety of non-aqueous electrolytes, highlighting the versatility of macromolecular design in implementing next-generation redox-flow batteries.« less

  11. Multiscale modelling of evolving foams

    NASA Astrophysics Data System (ADS)

    Saye, R. I.; Sethian, J. A.

    2016-06-01

    We present a set of multi-scale interlinked algorithms to model the dynamics of evolving foams. These algorithms couple the key effects of macroscopic bubble rearrangement, thin film drainage, and membrane rupture. For each of the mechanisms, we construct consistent and accurate algorithms, and couple them together to work across the wide range of space and time scales that occur in foam dynamics. These algorithms include second order finite difference projection methods for computing incompressible fluid flow on the macroscale, second order finite element methods to solve thin film drainage equations in the lamellae and Plateau borders, multiphase Voronoi Implicit Interface Methods to track interconnected membrane boundaries and capture topological changes, and Lagrangian particle methods for conservative liquid redistribution during rearrangement and rupture. We derive a full set of numerical approximations that are coupled via interface jump conditions and flux boundary conditions, and show convergence for the individual mechanisms. We demonstrate our approach by computing a variety of foam dynamics, including coupled evolution of three-dimensional bubble clusters attached to an anchored membrane and collapse of a foam cluster.

  12. Interactions between β-lactoglobulin and casein glycomacropeptide on foaming.

    PubMed

    Martinez, María J; Sánchez, Cecilio Carrera; Patino, Juan M Rodríguez; Pilosof, Ana M R

    2012-01-01

    The aim of this work was to study the effect of interactions between casein glycomacropeptide (CMP) and β-lactoglobulin (β-lg) at pH 6.5 and 3.5 on the foaming properties of the mixed systems with different CMP:β-lg ratios. The foaming properties were determined by the bubbling method with a Foamscan instrument. A highest overall foam capacity (OFC), foaming capacity (FC) and mainly stability of mixed foams at pH 3.5, as compared to the mixed foams at pH 6.5 or the foams of CMP and β-lg was observed. At pH 6.5, the stability of mixed foams decreased with increasing the CMP content, while OFC and FC values were similar to β-lg foam. The performance of the mixed systems was discussed in relation with the interactions between CMP and β-lg in the aqueous phase (as observed by dynamic light scattering and differential scanning calorimetry in previous works).

  13. Shooting in a foam.

    PubMed

    Le Goff, Anne; Quéré, David; Clanet, Christophe

    2014-09-21

    We study the motion of a solid sphere after its fast impact on a bath of liquid foam. We identify two regimes of deceleration. At short times, the velocity is still large and the foam behaves similar to a Newtonian fluid of constant viscosity. Then we measure a velocity threshold below which the sphere starts experiencing the foam's elasticity. We interpret this behavior using a visco-elasto-plastic model for foam rheology. Finally we discuss the possibility of stopping a projectile in the foam, and evaluate the capture efficiency.

  14. Structural graphitic carbon foams

    SciTech Connect

    Kearns, K.M.; Anderson, H.J.

    1998-12-31

    Graphitic carbon foams are a unique material form with very high structural and thermal properties at a light weight. A process has been developed to produce microcellular, open-celled graphitic foams. The process includes heating a mesophase pitch preform above the pitch melting temperature in a pressurized reactor. At the appropriate time, the pressure is released, the gas nucleates bubbles, and these bubbles grow forming the pitch into the foam structure. The resultant foamed pitch is then stabilized in an oxygen environment. At this point a rigid structure exists with some mechanical integrity. The foam is then carbonized to 800 C followed by a graphitization to 2700 C. The shear action from the growing bubbles aligns the graphitic planes along the foam struts to provide the ideal structure for good mechanical properties. Some of these properties have been characterized for some of the foam materials. It is known that variations of the blowing temperature, blowing pressure and saturation time result in foams of variously sized with mostly open pores; however, the mechanism of bubble nucleation is not known. Therefore foams were blown with various gases to begin to determine the nucleation method. These gases are comprised of a variety of molecular weights as well as a range of various solubility levels. By examining the resultant structures of the foam, differences were noted to develop an explanation of the foaming mechanism.

  15. Foam consolidation and drainage.

    PubMed

    Jun, S; Pelot, D D; Yarin, A L

    2012-03-27

    A theoretical model of foam as a consolidating continuum is proposed. The general model is applied to foam in a gravity settler. It is predicted that liquid drainage from foam in a gravity settler begins with a slow drainage stage. Next, a stage with faster drainage occurs where the drainage rate doubles compared to the initial stage. The experiments conducted within the framework of this work confirmed the theoretical predictions and allowed measurements of foam characteristics. Foams of three different concentrations of Pantene Pro-V Classic Care Solutions shampoo were studied, as well as the addition of polyethylene oxide (PEO) in one case. The shampoo's main foaming components are sodium lauryl sulfate and sodium laureth sulfate. It is shown to what extent foam drainage is slowed down by using higher shampoo concentrations and how it is further decreased by adding polymer (PEO).

  16. Foamed cement job successful in deep HTHP offshore well

    SciTech Connect

    Benge, O.G.; McDermott, J.R.; Langlinais, J.C.; Griffith, J.E.

    1996-03-11

    A foamed cement slurry successfully isolated problem formations behind a liner in a high-temperature/high-pressure (HTHP) well in Mobile Bay. The foamed cement slurry, with an average density of 11.8 ppg, was used to cement about 10,000 ft of a 9 5/8 inch. liner. Foamed cement has classically been considered when light-weight slurries are required. In this application, the use of foamed cement was not for its light-weight properties but rather for its unique performance in high-stress environments. Both offshore and zero-discharge requirements had to be met, and special considerations for each were addressed in this operation. Previous research has shown benefits of compressible slurries in preventing flow after cementing. The study was geared toward gas flow rather than fluid flow, but additional work indicates that foamed cement can be effective in preventing both gas and fluid migration. Based in part on this work and the study on temperature-induced stress failure of cement, a foamed slurry appeared to be an appropriate choice. In an attempt to address these problems, a 15.0-ppg Class H cement system foamed with nitrogen was used on this liner job. Because of the high temperatures in this well, the slurry was stabilized with 35% silica fluor. Other additives for retardation, foaming agent, and foam stabilizers were added as liquids. This paper reviews the performance and handling procedures of this cementing operation.

  17. Fundamentals of foam transport in porous media

    SciTech Connect

    Kovscek, A.R.; Radke, C.J.

    1993-10-01

    Foam in porous media is a fascinating fluid both because of its unique microstructure and because its dramatic influence on the flow of gas and liquid. A wealth of information is now compiled in the literature describing foam generation, destruction, and transport mechanisms. Yet there are conflicting views of these mechanisms and on the macroscopic results they produce. By critically reviewing how surfactant formulation and porous media topology conspire to control foam texture and flow resistance, we attempt to unify the disparate viewpoints. Evolution of texture during foam displacement is quantified by a population balance on bubble concentration, which is designed specifically for convenient incorporation into a standard reservoir simulator. Theories for the dominant bubble generation and coalescence mechanisms provide physically based rate expressions for the proposed population balance. Stone-type relative permeability functions along with the texture-sensitive and shear-thinning nature of confined foam complete the model. Quite good agreement is found between theory and new experiments for transient foam displacement in linear cores.

  18. Mechanical properties and network structure of wheat gluten foams.

    PubMed

    Blomfeldt, Thomas O J; Kuktaite, Ramune; Johansson, Eva; Hedenqvist, Mikael S

    2011-05-09

    This Article reports the influence of the protein network structure on the mechanical properties of foams produced from commercial wheat gluten using freeze-drying. Foams were produced from alkaline aqueous solutions at various gluten concentrations with or without glycerol, modified with bacterial cellulose nanosized fibers, or both. The results showed that 20 wt % glycerol was sufficient for plasticization, yielding foams with low modulus and high strain recovery. It was found that when fibers were mixed into the foams, a small but insignificant increase in elastic modulus was achieved, and the foam structure became more homogeneous. SEM indicated that the compatibility between the fibers and the matrix was good, with fibers acting as bridges in the cell walls. IR spectroscopy and SE-HPLC revealed a relatively low degree of aggregation, which was highest in the presence of glycerol. Confocal laser scanning microscopy revealed distinct differences in HMW-glutenin subunits and gliadin distributions for all of the different samples.

  19. Foam and gel methods for the decontamination of metallic surfaces

    DOEpatents

    Nunez, Luis; Kaminski, Michael Donald

    2007-01-23

    Decontamination of nuclear facilities is necessary to reduce the radiation field during normal operations and decommissioning of complex equipment. In this invention, we discuss gel and foam based diphosphonic acid (HEDPA) chemical solutions that are unique in that these solutions can be applied at room temperature; provide protection to the base metal for continued applications of the equipment; and reduce the final waste form production to one step. The HEDPA gels and foams are formulated with benign chemicals, including various solvents, such as ionic liquids and reducing and complexing agents such as hydroxamic acids, and formaldehyde sulfoxylate. Gel and foam based HEDPA processes allow for decontamination of difficult to reach surfaces that are unmanageable with traditional aqueous process methods. Also, the gel and foam components are optimized to maximize the dissolution rate and assist in the chemical transformation of the gel and foam to a stable waste form.

  20. Non-aqueous carbon black suspensions for lithium-based redox flow batteries: rheology and simultaneous rheo-electrical behavior.

    PubMed

    Youssry, Mohamed; Madec, Lénaïc; Soudan, Patrick; Cerbelaud, Manuella; Guyomard, Dominique; Lestriez, Bernard

    2013-09-14

    We report on the rheological and electrical properties of non-aqueous carbon black (CB) suspensions at equilibrium and under steady shear flow. The smaller the primary particle size of carbon black is, the higher the magnitude of rheological parameters and the conductivity are. The electrical percolation threshold ranges seem to coincide with the strong gel rather than the weak gel rheological threshold ones. The simultaneous measurements of electrical properties under shear flow reveal the well-known breaking-and-reforming mechanism that characterises such complex fluids. The small shear rate breaks up the network into smaller agglomerates, which in turn transform into anisometric eroded ones at very high shear rates, recovering the network conductivity. The type of carbon black, its concentration range and the flow rate range are now precisely identified for optimizing the performance of a redox flow battery. A preliminary electrochemical study for a composite anolyte (CB/Li4Ti5O12) at different charge-discharge rates and thicknesses is shown.

  1. Magnetic self-assembly of microparticle clusters in an aqueous two-phase microfluidic cross-flow

    NASA Astrophysics Data System (ADS)

    Abbasi, Niki; Jones, Steven G.; Moon, Byeong-Ui; Tsai, Scott S. H.

    2015-11-01

    We present a technique that self-assembles paramagnetic microparticles on the interface of aqueous two-phase system (ATPS) fluids in a microfluidic cross-flow. A co-flow of the ATPS is formed in the microfluidic cross channel as the flows of a dilute dextran (DEX) phase, along with a flow-focused particle suspension, converges with a dilute polyethylene glycol (PEG) phase. The microparticles arrive at the liquid-liquid interface and self-assemble into particle clusters due to forces on the particles from an applied external magnetic field gradient, and the interfacial tension of the ATPS. The microparticles form clusters at the interface, and once the cluster size grows to a critical value, the cluster passes through the interface. We control the size of the self-assembled clusters, as they pass through the interface, by varying the strength of the applied magnetic field gradient and the ATPS interfacial tension. We observe rich assembly dynamics, from the formation of Pickering emulsions to clusters that are completely encapsulated inside DEX phase droplets. We anticipate that this microparticle self-assembly method may have important biotechnological applications that require the controlled assembly of cells into clusters.

  2. Rheology of Foam Near the Order-Disorder Transition

    NASA Technical Reports Server (NTRS)

    Holt, R. Glynn; McDaniel, J. Gregory

    2001-01-01

    The first part of our research results are summarized in the recent journal publication: J. Gregory McDaniel and R. Glynn Holt, 'Measurement of aqueous foam rheology by acoustic levitation', Phys. Rev. E 61, 2204 (2000). This aspect of the work was a combination of experiment and analysis. We built a levitation system capable of acoustically levitating small samples of aqueous foam of arbitrary gas and liquid volume fractions. We then modulated the acoustic field to induce normal mode oscillations of the foam samples. The observables from the experiment were frequency and mode number. For dry (roughly > 70% gas by volume) foams and small deformations, we developed an effective medium, normal-modes analysis which took the frequency and mode number from experiment, and gave us the shear elastic modulus of the foam as a function of Poisson's ratio. The second part of our results may be found in a soon-to-be submitted manuscript 'Dynamics of aqueous foam drops', I.Sh. Akhatov, J.G. McDaniel and R.G. Holt, describing our modeling in the wet foam limit by considering the acoustic problem. This aspect of the research is purely theoretical. Beginning from a mass-conserving mixture law, the fully nonlinear equations of motion for a wet (roughly < 10% gas by volume) foam drop of initially spherical shape were derived. The frequencies for normal mode oscillations were derived in the linear inviscid limit. The nonlinear equations were numerically solved to elicit the motion of a foam drop under acoustic excitation. The role of the time-varying void fraction in breathing-mode oscillations is of particular interest. As of the end of the current (NAG#3-2121) grant, this work was not yet concluded. We continue to work on this aspect in order to extend the analysis to cover the transition regime of gas volume fractions, as well as to compare to experiments in the wet regime.

  3. Rheology of Foam Near the Order-Disorder Transition

    NASA Technical Reports Server (NTRS)

    Holt, R. Glynn; McDaniel, J. Gregory

    2001-01-01

    The first part of our research results are summarized in the recent journal publication: J. Gregory McDaniel and R. Glynn Holt, 'Measurement of aqueous foam rheology by acoustic levitation', Phys. Rev. E 61, 2204 (2000). This aspect of the work was a combination of experiment and analysis. We built a levitation system capable of acoustically levitating small samples of aqueous foam of arbitrary gas and liquid volume fractions. We then modulated the acoustic field to induce normal mode oscillations of the foam samples. The observables from the experiment were frequency and mode number. For dry (roughly > 70% gas by volume) foams and small deformations, we developed an effective medium, normal-modes analysis which took the frequency and mode number from experiment, and gave us the shear elastic modulus of the foam as a function of Poisson's ratio. The second part of our results may be found in a soon-to-be submitted manuscript 'Dynamics of aqueous foam drops', I.Sh. Akhatov, J.G. McDaniel and R.G. Holt, describing our modeling in the wet foam limit by considering the acoustic problem. This aspect of the research is purely theoretical. Beginning from a mass-conserving mixture law, the fully nonlinear equations of motion for a wet (roughly < 10% gas by volume) foam drop of initially spherical shape were derived. The frequencies for normal mode oscillations were derived in the linear inviscid limit. The nonlinear equations were numerically solved to elicit the motion of a foam drop under acoustic excitation. The role of the time-varying void fraction in breathing-mode oscillations is of particular interest. As of the end of the current (NAG#3-2121) grant, this work was not yet concluded. We continue to work on this aspect in order to extend the analysis to cover the transition regime of gas volume fractions, as well as to compare to experiments in the wet regime.

  4. Automated determination of nitrate plus nitrite in aqueous samples with flow injection analysis using vanadium (III) chloride as reductant.

    PubMed

    Wang, Shu; Lin, Kunning; Chen, Nengwang; Yuan, Dongxing; Ma, Jian

    2016-01-01

    Determination of nitrate in aqueous samples is an important analytical objective for environmental monitoring and assessment. Here we report the first automatic flow injection analysis (FIA) of nitrate (plus nitrite) using VCl3 as reductant instead of the well-known but toxic cadmium column for reducing nitrate to nitrite. The reduced nitrate plus the nitrite originally present in the sample react with the Griess reagent (sulfanilamide and N-1-naphthylethylenediamine dihydrochloride) under acidic condition. The resulting pink azo dye can be detected at 540 nm. The Griess reagent and VCl3 are used as a single mixed reagent solution to simplify the system. The various parameters of the FIA procedure including reagent composition, temperature, volume of the injection loop, and flow rate were carefully investigated and optimized via univariate experimental design. Under the optimized conditions, the linear range and detection limit of this method are 0-100 µM (R(2)=0.9995) and 0.1 µM, respectively. The targeted analytical range can be easily extended to higher concentrations by selecting alternative detection wavelengths or increasing flow rate. The FIA system provides a sample throughput of 20 h(-1), which is much higher than that of previously reported manual methods based on the same chemistry. National reference solutions and different kinds of aqueous samples were analyzed with our method as well as the cadmium column reduction method. The results from our method agree well with both the certified value and the results from the cadmium column reduction method (no significant difference with P=0.95). The spiked recovery varies from 89% to 108% for samples with different matrices, showing insignificant matrix interference in this method.

  5. Fabrication of Reticulated Graphitic Foam.

    DTIC Science & Technology

    2007-11-02

    mesophase pitch (MP). Mesophase pitch is...goes through several heat treatments to stabilize the mesophase pitch , burn out the polyurethane, carbonize and finally graphitize the foam, all the while maintaining the same morphology as the initial polyurethane foam....struts gives some initial molecular orientation. The dipped foam is dried, leaving behind a the polyurethane foam coated with the pitch . The foam

  6. Operator spin foam models

    NASA Astrophysics Data System (ADS)

    Bahr, Benjamin; Hellmann, Frank; Kamiński, Wojciech; Kisielowski, Marcin; Lewandowski, Jerzy

    2011-05-01

    The goal of this paper is to introduce a systematic approach to spin foams. We define operator spin foams, that is foams labelled by group representations and operators, as our main tool. A set of moves we define in the set of the operator spin foams (among other operations) allows us to split the faces and the edges of the foams. We assign to each operator spin foam a contracted operator, by using the contractions at the vertices and suitably adjusted face amplitudes. The emergence of the face amplitudes is the consequence of assuming the invariance of the contracted operator with respect to the moves. Next, we define spin foam models and consider the class of models assumed to be symmetric with respect to the moves we have introduced, and assuming their partition functions (state sums) are defined by the contracted operators. Briefly speaking, those operator spin foam models are invariant with respect to the cellular decomposition, and are sensitive only to the topology and colouring of the foam. Imposing an extra symmetry leads to a family we call natural operator spin foam models. This symmetry, combined with assumed invariance with respect to the edge splitting move, determines a complete characterization of a general natural model. It can be obtained by applying arbitrary (quantum) constraints on an arbitrary BF spin foam model. In particular, imposing suitable constraints on a spin(4) BF spin foam model is exactly the way we tend to view 4D quantum gravity, starting with the BC model and continuing with the Engle-Pereira-Rovelli-Livine (EPRL) or Freidel-Krasnov (FK) models. That makes our framework directly applicable to those models. Specifically, our operator spin foam framework can be translated into the language of spin foams and partition functions. Among our natural spin foam models there are the BF spin foam model, the BC model, and a model corresponding to the EPRL intertwiners. Our operator spin foam framework can also be used for more general spin

  7. Hydrodynamics of wet foams

    NASA Astrophysics Data System (ADS)

    Langevin, Dominique; Saint-Jalmes, Arnaud; Marze, Sébastien; Cox, Simon; Hutzler, Stefan; Drenckhan, Wiebke; Weaire, Denis; Caps, Hervé; Vandewalle, Nicolas; Adler, Micheàle; Pitois, Olivier; Rouyer, Florence; Cohen-Addad, Sylvie; Höhler, Reinhard; Ritacco, Hernan

    2005-10-01

    Foams and foaming pose important questions and problems to the chemical industry. As a material, foam is unusual in being a desired product while also being an unwanted byproduct within industry. Liquid foams are an essential part of gas/liquid contacting processes such as distillation and absorption, but over-production of foam in these processes can lead to downtime and loss of efficiency. Solid polymeric foams, such as polystyrene and polyurethane, find applications as insulation panels in the construction industry. Their combination of low weight and unique elastic/plastic properties make them ideal as packing and cushioning materials. Foams made with proteins are extensively used in the food industry. Despite the fact that foam science is a rapidly maturing field, critical aspects of foam physics and chemistry remain unclear. Several gaps in knowledge were identified to be tackled as the core of this MAP project. In addition, microgravity affords conditions for extending our understanding far beyond the possibilities offered by ground-based investigation. This MAP project addresses the challenges posed by the physics of foams under microgravity.

  8. Intraocular Pressure and the Mechanisms Involved in Resistance of the Aqueous Humor Flow in the Trabecular Meshwork Outflow Pathways.

    PubMed

    Tamm, Ernst R; Braunger, Barbara M; Fuchshofer, Rudolf

    2015-01-01

    Intraocular pressure (IOP), the critical risk factor for glaucoma, is generated and maintained by the aqueous humor circulation system. Aqueous humor is secreted from the epithelial layers of the ciliary body and exits the eye through the trabecular meshwork or the uveoscleral outflow pathways. IOP builds up in response to a resistance to aqueous humor flow in the trabecular outflow pathways. The trabecular outflow resistance is localized in the inner wall region, which comprises the juxtacanalicular connective tissue (JCT) and the inner wall endothelium of Schlemm's canal (SC). Outflow resistance in this region is lowered through the relaxation of contractile myofibroblast-like cells in trabecular meshwork and the adjacent scleral spur, or the contraction of the ciliary muscle. In primary open-angle glaucoma, the most frequent form of glaucoma, outflow resistance of the inner wall region is typically higher than normal. There is evidence that the increase in resistance is related to characteristic biological changes in the resident cells of the JCT, which more and more acquire the structural and functional characteristics of contractile myofibroblasts. The changes involve an augmentation of their actin cytoskeleton and of their surrounding fibrillary extracellular matrix, which connects to JCT cells via integrins. This scenario leads to an overall stiffening of the inner wall region, and is modulated by transforming growth factor-β/connective tissue growth factor signaling. Essentially comparable changes appear to occur in SC endothelial cells. Stiffening of JCT and SC cells is very likely a critical causative factor for the increase in trabecular outflow resistance in POAG.

  9. An Aqueous Redox Flow Battery Based on Neutral Alkali Metal Ferri/ferrocyanide and Polysulfide Electrolytes

    SciTech Connect

    Wei, Xiaoliang; Xia, Gordon; Kirby, Brent W.; Thomsen, Edwin C.; Li, Bin; Nie, Zimin; Graff, Gordon L.; Liu, Jun; Sprenkle, Vincent L.; Wang, Wei

    2015-11-13

    Aiming to explore low-cost redox flow battery systems, a novel iron-polysulfide (Fe/S) flow battery has been demonstrated in a laboratory cell. This system employs alkali metal ferri/ferrocyanide and alkali metal polysulfides as the redox electrolytes. When proper electrodes, such as pretreated graphite felts, are used, 78% energy efficiency and 99% columbic efficiency are achieved. The remarkable advantages of this system over current state-of-the-art redox flow batteries include: 1) less corrosive and relatively environmentally benign redox solutions used; 2) excellent energy and utilization efficiencies; 3) low cost for redox electrolytes and cell components. These attributes can lead to significantly reduced capital cost and make the Fe/S flow battery system a promising low-cost energy storage technology. The major drawbacks of the present cell design are relatively low power density and possible sulfur species crossover. Further work is underway to address these concerns.

  10. Syringe-pump-induced fluctuation in all-aqueous microfluidic system implications for flow rate accuracy.

    PubMed

    Li, Zida; Mak, Sze Yi; Sauret, Alban; Shum, Ho Cheung

    2014-02-21

    We report a new method to display the minute fluctuations induced by syringe pumps on microfluidic flows by using a liquid-liquid system with an ultralow interfacial tension. We demonstrate that the stepper motor inside the pump is a source of fluctuations in microfluidic flows by comparing the frequencies of the ripples observed at the interface to that of the pulsation of the stepper motor. We also quantify the fluctuations induced at different flow rates, using syringes of different diameters, and using different syringe pumps with different advancing distances per step. Our work provides a way to predict the frequency of the fluctuation that the driving syringe pump induces on a microfluidic system and suggests that syringe pumps can be a source of fluctuations in microfluidic flows, thus contributing to the polydispersity of the resulting droplets.

  11. The impact of pH on side reactions for aqueous redox flow batteries based on nitroxyl radical compounds

    NASA Astrophysics Data System (ADS)

    Orita, A.; Verde, M. G.; Sakai, M.; Meng, Y. S.

    2016-07-01

    Electrochemical and UV-VIS measurements demonstrate that the pH value of a 4-hydroxy-2,2,6,6-tetramethyl-1-pipperidinyloxyl (TEMPOL) electrolyte significantly impacts its redox reversibility. The diffusion coefficient and kinetic rate constant of TEMPOL in neutral aqueous solution are determined and shown to be comparable to those of vanadium ions used for industrially utilized redox flow batteries (RFBs). RFBs that incorporate a TEMPOL catholyte and Zn-based anolyte have an average voltage of 1.46 V and an energy efficiency of 80.4% during the initial cycle, when subject to a constant current of 10 mA cm-2. We demonstrate several factors that significantly influence the concentration and capacity retention of TEMPOL upon cycling; namely, pH and atmospheric gases dissolved in electrolyte. We expand upon the known reactions of TEMPOL in aqueous electrolyte and propose several concepts to improve its electrochemical performance in a RFB. Controlling these factors will be the key to enable the successful implementation of this relatively inexpensive and environmentally friendly battery.

  12. Practical thermodynamic quantities for aqueous vanadium- and iron-based flow batteries

    SciTech Connect

    Hudak, Nicholas S.

    2013-12-31

    A simple method for experimentally determining thermodynamic quantities for flow battery cell reactions is presented. Equilibrium cell potentials, temperature derivatives of cell potential (dE/dT), Gibbs free energies, and entropies are reported here for all-vanadium, iron–vanadium, and iron–chromium flow cells with state-of-the-art solution compositions. Proof is given that formal potentials and formal temperature coefficients can be used with modified forms of the Nernst Equation to quantify the thermodynamics of flow cell reactions as a function of state-of-charge. Such empirical quantities can be used in thermo-electrochemical models of flow batteries at the cell or system level. In most cases, the thermodynamic quantities measured here are significantly different from standard values reported and used previously in the literature. The data reported here are also useful in the selection of operating temperatures for flow battery systems. Because higher temperatures correspond to lower equilibrium cell potentials for the battery chemistries studied here, it can be beneficial to charge a cell at higher temperature and discharge at lower temperature. As a result, proof-of-concept of improved voltage efficiency with the use of such non-isothermal cycling is given for the all-vanadium redox flow battery, and the effect is shown to be more pronounced at lower current densities.

  13. Practical thermodynamic quantities for aqueous vanadium- and iron-based flow batteries

    DOE PAGES

    Hudak, Nicholas S.

    2013-12-31

    A simple method for experimentally determining thermodynamic quantities for flow battery cell reactions is presented. Equilibrium cell potentials, temperature derivatives of cell potential (dE/dT), Gibbs free energies, and entropies are reported here for all-vanadium, iron–vanadium, and iron–chromium flow cells with state-of-the-art solution compositions. Proof is given that formal potentials and formal temperature coefficients can be used with modified forms of the Nernst Equation to quantify the thermodynamics of flow cell reactions as a function of state-of-charge. Such empirical quantities can be used in thermo-electrochemical models of flow batteries at the cell or system level. In most cases, the thermodynamic quantitiesmore » measured here are significantly different from standard values reported and used previously in the literature. The data reported here are also useful in the selection of operating temperatures for flow battery systems. Because higher temperatures correspond to lower equilibrium cell potentials for the battery chemistries studied here, it can be beneficial to charge a cell at higher temperature and discharge at lower temperature. As a result, proof-of-concept of improved voltage efficiency with the use of such non-isothermal cycling is given for the all-vanadium redox flow battery, and the effect is shown to be more pronounced at lower current densities.« less

  14. Monolithic Ceramic Foams for Ultrafast Photocatalytic Inactivation of Bacteria

    PubMed Central

    Wu, Pinggui; Xie, Rongcai; Imlay, Kari; Shang, Jian Ku

    2011-01-01

    Palladium-modified nitrogen-doped titanium dioxide (TiON/PdO) foams were synthesized by a sol-gel process on a polyurethane foam template. The TiON/PdO foam was tested for microbial killing using Escherichia coli cells as a target. Under visible-light illumination, the TiON/PdO foam displayed a strong antimicrobial effect on the bacteria cells in water. The antimicrobial effect was found to be dependent on the palladium content and the calcination temperature. In a flow-through dynamic photoreactor, the new photocatalyst efficiently inactivated E. coli within a short contact time (< 1 min), the shortest ever reported for photocatalytic killing of bacteria. The strong antimicrobial functions of the TiON/PdO foam were related to the charge trapping by PdO and to the high contact efficiency of the foam structure. PMID:21423830

  15. Performance and cost characteristics of multi-electron transfer, common ion exchange non-aqueous redox flow batteries

    NASA Astrophysics Data System (ADS)

    Laramie, Sydney M.; Milshtein, Jarrod D.; Breault, Tanya M.; Brushett, Fikile R.; Thompson, Levi T.

    2016-09-01

    Non-aqueous redox flow batteries (NAqRFBs) have recently received considerable attention as promising high energy density, low cost grid-level energy storage technologies. Despite these attractive features, NAqRFBs are still at an early stage of development and innovative design techniques are necessary to improve performance and decrease costs. In this work, we investigate multi-electron transfer, common ion exchange NAqRFBs. Common ion systems decrease the supporting electrolyte requirement, which subsequently improves active material solubility and decreases electrolyte cost. Voltammetric and electrolytic techniques are used to study the electrochemical performance and chemical compatibility of model redox active materials, iron (II) tris(2,2‧-bipyridine) tetrafluoroborate (Fe(bpy)3(BF4)2) and ferrocenylmethyl dimethyl ethyl ammonium tetrafluoroborate (Fc1N112-BF4). These results help disentangle complex cycling behavior observed in flow cell experiments. Further, a simple techno-economic model demonstrates the cost benefits of employing common ion exchange NAqRFBs, afforded by decreasing the salt and solvent contributions to total chemical cost. This study highlights two new concepts, common ion exchange and multi-electron transfer, for NAqRFBs through a demonstration flow cell employing model active species. In addition, the compatibility analysis developed for asymmetric chemistries can apply to other promising species, including organics, metal coordination complexes (MCCs) and mixed MCC/organic systems, enabling the design of low cost NAqRFBs.

  16. Study and characterization of positive electrolytes for application in the aqueous all-copper redox flow battery

    NASA Astrophysics Data System (ADS)

    Sanz, Laura; Lloyd, David; Magdalena, Eva; Palma, Jesús; Anderson, Marc; Kontturi, Kyösti

    2015-03-01

    In recent studies, the employment of the aqueous solution system comprised of Cu(II)-Cu(I)-Cl system was addressed for massive energy storage in Redox Flow Batteries (RFBs) [5,6], providing important practical advantages compared to the widespread all-vanadium or Zn/Br systems [5]. The substitution of vanadium electrolytes by copper-chloride electrolytes allows the simplification of the process and notably reduces the cost, allowing for a better commercialization of RFBs. Here, a complete physico-chemical characterization of positive copper electrolytes and their electrochemical performance using different supporting electrolytes, HCl and CaCl2, is presented. Once the physical properties and the electrochemical performance of each one of the supporting electrolytes were determined, the final composition of supporting electrolyte for this Cu(II)/Cu(I) redox couple could be optimized by mixing different sources of chloride, regarding its practical application in the all-copper RFB.

  17. Orbital foamed material extruder

    NASA Technical Reports Server (NTRS)

    Tucker, Dennis S. (Inventor)

    2009-01-01

    This invention is a process for producing foamed material in space comprising the steps of: rotating the material to simulate the force of gravity; heating the rotating material until it is molten; extruding the rotating, molten material; injecting gas into the extruded, rotating, molten material to produce molten foamed material; allowing the molten foamed material to cool to below melting temperature to produce the foamed material. The surface of the extruded foam may be heated to above melting temperature and allowed to cool to below melting temperature. The extruded foam may also be cut to predetermined length. The starting material may be metal or glass. Heating may be accomplished by electrical heating elements or by solar heating.

  18. Amorphous metallic foam

    NASA Astrophysics Data System (ADS)

    Schroers, Jan; Veazey, Chris; Johnson, William L.

    2003-01-01

    The bulk glass forming alloy Pd43Ni10Cu27P20 is processed into a low-density amorphous metallic foam. Pd43Ni10Cu27P20 is mixed with hydrated B2O3, which releases gas at elevated temperature and/or low pressure. Very homogeneous foams are achieved due to the high viscosity of the alloy even at its liquidus temperature. By processing at the liquidus temperature and decreasing the pressure to 10-2 mbar, well-distributed bubbles expand to foam the material. Foam densities as low as 1.4×103 kg/m3 were obtained, corresponding to a bubble volume fraction of 84%. The bubble diameter ranges between 2×10-4 and 1×10-3 m. Thermal analysis by differential scanning calorimetry confirms the amorphous nature of the foam. Furthermore, it reveals that the foam's thermal stability is comparable to the bulk material.

  19. Structure of random foam.

    SciTech Connect

    Reinelt, Douglas A.; van Swol, Frank B.; Kraynik, Andrew Michael

    2004-06-01

    The Surface Evolver was used to compute the equilibrium microstructure of dry soap foams with random structure and a wide range of cell-size distributions. Topological and geometric properties of foams and individual cells were evaluated. The theory for isotropic Plateau polyhedra describes the dependence of cell geometric properties on their volume and number of faces. The surface area of all cells is about 10% greater than a sphere of equal volume; this leads to a simple but accurate theory for the surface free energy density of foam. A novel parameter based on the surface-volume mean bubble radius R32 is used to characterize foam polydispersity. The foam energy, total cell edge length, and average number of faces per cell all decrease with increasing polydispersity. Pentagonal faces are the most common in monodisperse foam but quadrilaterals take over in highly polydisperse structures.

  20. Structure of Random Foam

    NASA Astrophysics Data System (ADS)

    Kraynik, Andrew M.; Reinelt, Douglas A.; van Swol, Frank

    2004-11-01

    The Surface Evolver was used to compute the equilibrium microstructure of dry soap foams with random structure and a wide range of cell-size distributions. Topological and geometric properties of foams and individual cells were evaluated. The theory for isotropic Plateau polyhedra describes the dependence of cell geometric properties on their volume and number of faces. The surface area of all cells is about 10% greater than a sphere of equal volume; this leads to a simple but accurate theory for the surface free energy density of foam. A novel parameter based on the surface-volume mean bubble radius R32 is used to characterize foam polydispersity. The foam energy, total cell edge length, and average number of faces per cell all decrease with increasing polydispersity. Pentagonal faces are the most common in monodisperse foam but quadrilaterals take over in highly polydisperse structures.

  1. Fire-retardant foams

    NASA Technical Reports Server (NTRS)

    Gagliani, J.

    1978-01-01

    Family of polyimide resins are being developed as foams with exceptional fire-retardant properties. Foams are potentially useful for seat cushions in aircraft and ground vehicles and for applications such as home furnishings and building-construction materials. Basic formulations can be modified with reinforcing fibers or fillers to produce celular materials for variety of applications. By selecting reactants, polymer structure can be modified to give foams with properties ranging from high resiliency and flexibility to brittleness and rigidity.

  2. High performance polymeric foams

    SciTech Connect

    Gargiulo, M.; Sorrentino, L.; Iannace, S.

    2008-08-28

    The aim of this work was to investigate the foamability of high-performance polymers (polyethersulfone, polyphenylsulfone, polyetherimide and polyethylenenaphtalate). Two different methods have been used to prepare the foam samples: high temperature expansion and two-stage batch process. The effects of processing parameters (saturation time and pressure, foaming temperature) on the densities and microcellular structures of these foams were analyzed by using scanning electron microscopy.

  3. Fire-retardant foams

    NASA Technical Reports Server (NTRS)

    Gagliani, J.

    1978-01-01

    Family of polyimide resins are being developed as foams with exceptional fire-retardant properties. Foams are potentially useful for seat cushions in aircraft and ground vehicles and for applications such as home furnishings and building-construction materials. Basic formulations can be modified with reinforcing fibers or fillers to produce celular materials for variety of applications. By selecting reactants, polymer structure can be modified to give foams with properties ranging from high resiliency and flexibility to brittleness and rigidity.

  4. Design and development of polyphenylene oxide foam as a reusable internal insulation for LH2 tanks

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Material specification and fabrication process procedures for foam production are presented. The properties of mechanical strength, modulus of elasticity, density and thermal conductivity were measured and related to foam quality. Properties unique to the foam such as a gas layer insulation, density gradient parallel to the fiber direction, and gas flow conductance in both directions were correlated with foam quality. Inspection and quality control tests procedures are outlined and photographs of test equipment and test specimens are shown.

  5. Effect of frozen storage on the foaming properties of wheat gliadin.

    PubMed

    Wang, Pei; Tao, Han; Wu, Fengfeng; Yang, Na; Chen, Feng; Jin, Zhengyu; Xu, Xueming

    2014-12-01

    In this study, the effect of frozen storage on the foaming properties of wheat gliadin was investigated and further elucidated by evaluating its physicochemical changes. The foaming volumes of gliadin solution decreased while the foaming stability increased during the frozen storage. This was directly attributed to decreased gliadin content and increased foam density and protein concentration involved in the foams. A more rigid conformation was observed when the frozen storage time increased: the α-helix structure increased at the cost of β-sheet and unordered structure with the decreased surface hydrophobicity and increased surface tension of gliadin aqueous solutions. The percentage of γ-gliadin within gliadin foams gradually decreased, indicating that γ-gliadin was the most sensitive to freezing and the main contributor to the weakened foaming properties during the frozen storage. This study extended the knowledge of gliadin deterioration upon frozen storage and might contribute to the better understanding of frozen dough quality loss.

  6. Investigating acoustic-induced deformations in a foam using multiple light scattering.

    PubMed

    Erpelding, M; Guillermic, R M; Dollet, B; Saint-Jalmes, A; Crassous, J

    2010-08-01

    We have studied the effect of an external acoustic wave on bubble displacements inside an aqueous foam. The signature of the acoustic-induced bubble displacements is found using a multiple light scattering technique, and occurs as a modulation on the photon correlation curve. Measurements for various sound frequencies and amplitudes are compared to analytical predictions and numerical simulations. These comparisons finally allow us to elucidate the nontrivial acoustic displacement profile inside the foam; in particular, we find that the acoustic wave creates a localized shear in the vicinity of the solid walls holding the foam, as a consequence of inertial contributions. This study of how bubbles "dance" inside a foam as a response to sound turns out to provide new insights on foam acoustics and sound transmission into a foam, foam deformation at high frequencies, and analysis of light scattering data in samples undergoing nonhomogeneous deformations.

  7. Aggregation behavior of fullerenes in aqueous solutions: a capillary electrophoresis and asymmetric flow field-flow fractionation study.

    PubMed

    Astefanei, Alina; Núñez, Oscar; Galceran, Maria Teresa; Kok, Wim Th; Schoenmakers, Peter J

    2015-10-01

    In this work, the electrophoretic behavior of hydrophobic fullerenes [buckminsterfullerene (C60), C70, and N-methyl-fulleropyrrolidine (C60-pyrr)] and water-soluble fullerenes [fullerol (C60(OH)24); polyhydroxy small gap fullerene, hydrated (C120(OH)30); C60 pyrrolidine tris acid (C60-pyrr tris acid); and (1,2-methanofullerene C60)-61-carboxylic acid (C60CHCOOH)] in micellar electrokinetic capillary chromatography (MECC) was evaluated. The aggregation behavior of the water-soluble compounds in MECC at different buffer and sodium dodecyl sulfate (SDS) concentrations and pH values of the background electrolyte (BGE) was studied by monitoring the changes observed in the electrophoretic pattern of the peaks. Broad and distorted peaks that can be attributed to fullerene aggregation were obtained in MECC which became narrower and more symmetric by working at low buffer and SDS concentrations (below the critical micelle concentration, capillary zone electrophoresis (CZE) conditions). For the characterization of the suspected aggregates formed (size and shape), asymmetrical flow field-flow fractionation (AF4) and transmission electron microscopy (TEM) were used. The results showed that the increase in the buffer concentration promoted the aggregation of the particles, while the presence of SDS micelles revealed multiple peaks corresponding to particles of different aggregation degrees. Furthermore, MECC has been applied for the first time for the analysis of C60 in two different cosmetic products (i.e., anti-aging serum and facial mask).

  8. Virtual Treatment of Basilar Aneurysms Using Shape Memory Polymer Foam

    PubMed Central

    Ortega, J.M.; Hartman, J.; Rodriguez, J.N.; Maitland, D.J.

    2013-01-01

    Numerical simulations are performed on patient-specific basilar aneurysms that are treated with shape memory polymer (SMP) foam. In order to assess the post-treatment hemodynamics, two modeling approaches are employed. In the first, the foam geometry is obtained from a micro-CT scan and the pulsatile blood flow within the foam is simulated for both Newtonian and non-Newtonian viscosity models. In the second, the foam is represented as a porous media continuum, which has permeability properties that are determined by computing the pressure gradient through the foam geometry over a range of flow speeds comparable to those of in vivo conditions. Virtual angiography and additional post-processing demonstrate that the SMP foam significantly reduces the blood flow speed within the treated aneurysms, while eliminating the high-frequency velocity fluctuations that are present within the pre-treatment aneurysms. An estimation of the initial locations of thrombus formation throughout the SMP foam is obtained by means of a low fidelity thrombosis model that is based upon the residence time and shear rate of blood. The Newtonian viscosity model and the porous media model capture similar qualitative trends, though both yield a smaller volume of thrombus within the SMP foam. PMID:23329002

  9. Virtual Treatment of Basilar Aneurysms Using Shape Memory Polymer Foam

    NASA Astrophysics Data System (ADS)

    Ortega, J. M.; Hartman, J.; Rodriguez, J. N.; Maitland, D. J.

    2012-11-01

    Numerical simulations are performed on patient-specific basilar aneurysms that are treated with shape memory polymer (SMP) foam. In order to assess the post-treatment hemodynamics, two modeling approaches are employed. In the first, the foam geometry is obtained from a micro-CT scan and the pulsatile blood flow within the foam is simulated for both Newtonian and non-Newtonian viscosity models. In the second, the foam is represented as a porous media continuum, which has permeability properties that are determined by computing the pressure gradient through the foam geometry over a range of flow speeds comparable to those of in vivo conditions. Virtual angiography and additional post-processing demonstrate that the SMP foam significantly reduces the blood flow speed within the treated aneurysms, while eliminating the high-frequency velocity fluctuations that are present prior to treatment. A prediction of the initial locations of thrombus formation throughout the SMP foam is obtained by means of a low fidelity thrombosis model that is based upon the residence time and shear rate of blood. The two modeling approaches capture similar qualitative trends for the initial locations of thrombus within the SMP foam.

  10. Velocity Field in a Vertical Foam Film

    NASA Astrophysics Data System (ADS)

    Seiwert, Jacopo; Kervil, Ronan; Nou, Soniraks; Cantat, Isabelle

    2017-01-01

    The drainage of vertical foam films governs their lifetime. For a foam film supported on a rectangular solid frame, when the interface presents a low resistance to shear, the drainage dynamics involves a complex flow pattern at the film scale, leading to a drainage time proportional to the frame width. Using an original velocimetry technique, based on fluorescent foam films and photobleaching, we measure the horizontal and vertical components of the velocity in a draining film, thus providing the first quantitative experimental evidence of this flow pattern. Upward velocities up to 10 cm /s are measured close to the lateral menisci, whereas a slower velocity field is obtained in the center of the film, with comparable downwards and horizontal components. Scaling laws are proposed for all characteristic velocities, coupling gravitational effects, and capillary suction.

  11. High Temperature Structural Foam

    NASA Technical Reports Server (NTRS)

    Weiser, Erik S.; Baillif, Faye F.; Grimsley, Brian W.; Marchello, Joseph M.

    1997-01-01

    The Aerospace Industry is experiencing growing demand for high performance polymer foam. The X-33 program needs structural foam insulation capable of retaining its strength over a wide range of environmental conditions. The High Speed Research Program has a need for low density core splice and potting materials. This paper reviews the state of the art in foam materials and describes experimental work to fabricate low density, high shear strength foam which can withstand temperatures from -220 C to 220 C. Commercially available polymer foams exhibit a wide range of physical properties. Some with densities as low as 0.066 g/cc are capable of co-curing at temperatures as high as 182 C. Rohacell foams can be resin transfer molded at temperatures up to 180 C. They have moduli of elasticity of 0.19 MPa, tensile strengths of 3.7 Mpa and compressive strengths of 3.6 MPa. The Rohacell foams cannot withstand liquid hydrogen temperatures, however Imi-Tech markets Solimide (trademark) foams which withstand temperatures from -250 C to 200 C, but they do not have the required structural integrity. The research activity at NASA Langley Research Center focuses on using chemical blowing agents to produce polyimide thermoplastic foams capable of meeting the above performance requirements. The combination of blowing agents that decompose at the minimum melt viscosity temperature together with plasticizers to lower the viscosity has been used to produce foams by both extrusion and oven heating. The foams produced exhibit good environmental stability while maintaining structural properties.

  12. Hyphenation of sequential- and flow injection analysis with FTIR-spectroscopy for chemical analysis in aqueous solutions

    NASA Astrophysics Data System (ADS)

    Lendl, B.; Schindler, R.; Kellner, R.

    1998-06-01

    A survey of the principles of sequential (SIA)-and flow injection analysis (FIA) systems with FTIR spectroscopic detection is presented to introduce these hyphenations as powerful techniques for performing chemical analysis in aqueous solution. The strength of FIA/SIA-FTIR systems lies in the possibility to perform highly reproducible and automated sample manipulations such as sample clean-up and/or chemical reactions prior to spectrum acquisition. It is shown that the hyphenation of FIA/SIA systems with an FTIR spectrometer enhances the problem solving capabilities of the FTIR spectrometer as also parameters which can not be measured directly (e.g. enzyme activities) can be determined. On the other hand application of FTIR spectroscopic detection in FIA or SIA is also of advantage as it allows to shorten conventional analysis procedures (e.g. sucrose or phosphate analysis) or to establish and apply a multivariate calibration model for simultaneous determinations (e.g. glucose, fructose and sucrose analysis). In addition to these examples two recent instrumental developments in miniaturized FIA/SIA-FTIR systems, a μ-Flow through cell based on IR fiber optics and a micromachined SI-enzyme reactor are presented in this paper.

  13. Metal-Organic Frameworks as Highly Active Electrocatalysts for High-Energy Density, Aqueous Zinc-Polyiodide Redox Flow Batteries.

    PubMed

    Li, Bin; Liu, Jian; Nie, Zimin; Wang, Wei; Reed, David; Liu, Jun; McGrail, Pete; Sprenkle, Vincent

    2016-07-13

    The new aqueous zinc-polyiodide redox flow battery (RFB) system with highly soluble active materials as well as ambipolar and bifunctional designs demonstrated significantly enhanced energy density, which shows great potential to reduce RFB cost. However, the poor kinetic reversibility and electrochemical activity of the redox reaction of I3(-)/I(-) couples on graphite felts (GFs) electrode can result in low energy efficiency. Two nanoporous metal-organic frameworks (MOFs), MIL-125-NH2 and UiO-66-CH3, that have high surface areas when introduced to GF surfaces accelerated the I3(-)/I(-) redox reaction. The flow cell with MOF-modified GFs serving as a positive electrode showed higher energy efficiency than the pristine GFs; increases of about 6.4% and 2.7% occurred at the current density of 30 mA/cm(2) for MIL-125-NH2 and UiO-66-CH3, respectively. Moreover, UiO-66-CH3 is more promising due to its excellent chemical stability in the weakly acidic electrolyte. This letter highlights a way for MOFs to be used in the field of RFBs.

  14. Chronicles of foam films.

    PubMed

    Gochev, G; Platikanov, D; Miller, R

    2016-07-01

    The history of the scientific research on foam films, traditionally known as soap films, dates back to as early as the late 17th century when Boyle and Hooke paid special attention to the colours of soap bubbles. Their inspiration was transferred to Newton, who began systematic study of the science of foam films. Over the next centuries, a number of scientists dealt with the open questions of the drainage, stability and thickness of foam films. The significant contributions of Plateau and Gibbs in the middle/late 19th century are particularly recognized. After the "colours" method of Newton, Reinold and Rücker as well as Johhonnot developed optical methods for measuring the thickness of the thinner "non-colour" films (first order black) that are still in use today. At the beginning of the 20th century, various aspects of the foam film science were elucidated by the works of Dewar and Perrin and later by Mysels. Undoubtedly, the introduction of the disjoining pressure by Derjaguin and the manifestation of the DLVO theory in describing the film stability are considered as milestones in the theoretical development of foam films. The study of foam films gained momentum with the introduction of the microscopic foam film methodology by Scheludko and Exerowa, which is widely used today. This historical perspective serves as a guide through the chronological development of knowledge on foam films achieved over several centuries.

  15. Microcellular foams; Here's how

    SciTech Connect

    Aubert, J.H.; Sylwester, A.P. )

    1991-05-01

    Close to a million tons of polystyrene foams are manufactured in the United States each year. This product is prepared by diffusing a blowing agent (usually 6% pentane) into beads and expanding the beads above the glass transition temperature of polystyrene (100{degrees} C). Each bubble nucleation site becomes the center of a roughly spherical foam cell, which has a diameter of 50 to 150 {mu}m. The use of these is based on their insulating and shockabsorbing capabilities. What if one wanted to make a package with a thickness of only 200{mu}m This paper reports that at Sandia National Laboratories, this is not as uncommon a request as one might think. A number of targets for high-energy physical experiments require low-density foam coatings or small low-density foam supports with dimensions smaller than a millimeter. The foam coatings within such a target could be made with a conventional foam, but because the entire thickness would contain as few as two or three cells it would look nonuniform. This is undesirable for physics applications that require homogeneous structural supports. For a given foam density, smaller celled foams have a larger interfacial area, a property useful in materials ranging from medical devices to catalyst supports.

  16. Enhancing the lateral-flow immunoassay for detection of proteins using an aqueous two-phase micellar system.

    PubMed

    Mashayekhi, Foad; Le, Alexander M; Nafisi, Parsa M; Wu, Benjamin M; Kamei, Daniel T

    2012-10-01

    The lateral-flow (immuno)assay (LFA) has been widely investigated for the detection of molecular, macromolecular, and particle targets at the point-of-need due to its ease of use, rapid processing, and minimal power and laboratory equipment requirements. However, for some analytes, such as certain proteins, the detection limit of LFA is inferior to lab-based assays, such as the enzyme-linked immunosorbent assay, and needs to be improved. One solution for improving the detection limit of LFA is to concentrate the target protein in a solution prior to the detection step. In this study, a novel approach was used in the context of an aqueous two-phase micellar system comprised of the nonionic surfactant Triton X-114 to concentrate a model protein, namely transferrin, prior to LFA. Proteins have been shown to partition, or distribute, fairly evenly between the two phases of an aqueous two-phase system, which in turn results in their limited concentration in one of the two phases. Therefore, larger colloidal gold particles decorated with antibodies for transferrin were used in the concentration step to bind to transferrin and aid its partitioning into the top, micelle-poor phase. By manipulating the volume ratio of the two coexisting micellar phases and combining the concentration step with LFA, the transferrin detection limit of LFA was improved by tenfold from 0.5 to 0.05 μg/mL in a predictive manner. In addition to enhancing the sensitivity of LFA, this universal concentration method could also be used to improve other detection assays.

  17. Effect of electrodiffusion current flow on electrostatic screening in aqueous pores

    NASA Astrophysics Data System (ADS)

    Liu, Yang; Sauer, Jon; Dutton, Robert W.

    2008-04-01

    A numerical study within the framework of the Poisson-Nernst-Planck equations is conducted to investigate electrostatic screening of charged biomolecules within synthetic pores having diameters of at least 10Debye lengths. We show that with external biases, the biomolecule charge is only partially screened due to the presence of electro-diffusion current flow. This is considerably different from the equilibrium Debye-Huckel screening behavior and will result in long-range electrostatic interactions. The potential application to direct biomolecule charge sensing is also discussed.

  18. Continuous flow room temperature reductive aqueous homo-coupling of aryl halides using supported Pd catalysts

    PubMed Central

    Feiz, Afsaneh; Bazgir, Ayoob; Balu, Alina M.; Luque, Rafael

    2016-01-01

    A convenient and environmentally friendly protocol for the preparation of biaryls at room temperature under continuous flow conditions is reported. A simple reductive homo-coupling Ullmann-type reaction was performed in an H-Cube mini using commercially available supported Pd catalysts under mild reaction conditions, with quantitative conversion to target products. Commercial Pd catalysts were found to be highly stable under the investigated reaction conditions, with a minimum Pd leaching into solution after several reaction runs (ca. 20 h on stream). PMID:27600989

  19. Trace determination of aqueous sulfite, sulfide, and methanethiol by fluorometric flow injection analysis

    SciTech Connect

    Dasgupta, P.K.; Yang, H.C.

    1986-11-01

    Preservation of sulfite, sulfide, and methanethiol in buffered formaldehyde and oxaldihydroxamic acid stabilizers has been studied. Flow injection analysis procedures that involve T mixing or membrane-based reagent introduction have been developed for the fast (24 samples/h) analysis of these anions based upon the reaction with N-acridinylmaleimide in a water-N,N-dimethylformamide medium to form a fluorescent product. Detection limits are 0.04, 0.60, and 0.80 ..mu..M, respectively, for the three sulfur species; differential analysis is possible.

  20. Foamed Bulk Metallic Glass (Foam) Investigation

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This soldering iron has an evacuated copper capsule at the tip that contains a pellet of Bulk Metallic Glass (BMG) aboard the International Space Station (ISS). Prior to flight, researchers sealed a pellet of bulk metallic glass mixed with microscopic gas-generating particles into the copper ampoule under vacuum. Once heated in space, such as in this photograph, the particles generated gas and the BMG becomes a viscous liquid. The released gas made the sample foam within the capsule where each microscopic particle formed a gas-filled pore within the foam. The inset image shows the oxidation of the sample after several minutes of applying heat. Although hidden within the brass sleeve, the sample retained the foam shape when cooled, because the viscosity increased during cooling until it was solid.

  1. Flow and morphological conditions associated with the directional solidification of aqueous ammonium chloride

    SciTech Connect

    Magirl, C.S.; Incropera, F.P.

    1993-01-01

    Using 27% aq. NH[sub 4]Cl solutions as transparent analog, shadowgraphy and dye injection were used to observe flow and morphology in unidirectional solidification (UDS) from below. Dendritic crystals that form at the cold surface reject lighter, solute-deficient fluid, and instability is shown by finger-type double-diffusive convection. As the mushy two-phase region grows, perturbations at the liquidus interface cause localized remelting and downward development of channels. Solsutal plumes emanate from the channels, and in time, double-diffusive convection layers also form in the melt. When the solution is chilled at the sides as well as at the bottom, conditions are influenced by detachment and settling of crystals from the sidewall and by plumes from slanted channels. When a slow, oscillatory rocking motion is imposed on UDS, the freckle-type segregates in the final cast is suppressed. Within the melt, plumes and double-diffusive convection are eliminated. Inertially induced convection mixes the melt and produces a dense slurry. Although channels are eliminated from the bottom mushy region, overall heat transfer and macrosegregation in the cavity are unaffected by the slow rocking. Numerical simulations qualitatively predict trends in the field variables and provide insights on interdendritic flows and macrosegregation (freckle-, A-type segregates), although its quantitative predictions are hampered by simplifying assumptions.

  2. Flow and morphological conditions associated with the directional solidification of aqueous ammonium chloride. Annual performance report

    SciTech Connect

    Magirl, C.S.; Incropera, F.P.

    1993-01-01

    Using 27% aq. NH{sub 4}Cl solutions as transparent analog, shadowgraphy and dye injection were used to observe flow and morphology in unidirectional solidification (UDS) from below. Dendritic crystals that form at the cold surface reject lighter, solute-deficient fluid, and instability is shown by finger-type double-diffusive convection. As the mushy two-phase region grows, perturbations at the liquidus interface cause localized remelting and downward development of channels. Solsutal plumes emanate from the channels, and in time, double-diffusive convection layers also form in the melt. When the solution is chilled at the sides as well as at the bottom, conditions are influenced by detachment and settling of crystals from the sidewall and by plumes from slanted channels. When a slow, oscillatory rocking motion is imposed on UDS, the freckle-type segregates in the final cast is suppressed. Within the melt, plumes and double-diffusive convection are eliminated. Inertially induced convection mixes the melt and produces a dense slurry. Although channels are eliminated from the bottom mushy region, overall heat transfer and macrosegregation in the cavity are unaffected by the slow rocking. Numerical simulations qualitatively predict trends in the field variables and provide insights on interdendritic flows and macrosegregation (freckle-, A-type segregates), although its quantitative predictions are hampered by simplifying assumptions.

  3. Effect of shear flow on the phase behavior of an aqueous gelatin-dextran emulsion.

    PubMed

    Antonov, Y A; Van Puyvelde, P; Moldenaers, P; Leuven, K U

    2004-01-01

    A rheo-optical methodology, based on small angle light scattering and transmitted light intensity measurements, has been used to study in situ and on a time resolved basis the shear induced morphology in ternary two-phase water-gelatin-dextran mixtures. Emulsions close to the binodal line as well as far from it have been investigated. It is shown that above a critical shear rate, shear-induced mixing occurs at the length scales probed by the laser light. It is hypothesized that the shear-induced homogenization is due to the shear forces that exceed the intermolecular forces of the self-association process of the gelatin. The isothermal phase diagram at a fixed shear rate has been determined. In addition, the structure evolution after cessation of flow has been studied. When flow is stopped after homogenization, phase separation occurs almost instantaneously. When subsequently applying a low shear rate, the structure coarsens due to coalescence of the dispersed droplets. The kinetics of this coalescence process is strain controlled.

  4. dugksFoam: An open source OpenFOAM solver for the Boltzmann model equation

    NASA Astrophysics Data System (ADS)

    Zhu, Lianhua; Chen, Songze; Guo, Zhaoli

    2017-04-01

    A deterministic Boltzmann model equation solver called dugksFoam has been developed in the framework of the open source CFD toolbox OpenFOAM. The solver adopts the discrete unified gas kinetic scheme (Guo et al., 2015) with the Shakhov collision model. It has been validated by simulating several test cases covering different flow regimes including the one dimensional shock tube problem, a two dimensional thermal induced flow and the three dimensional lid-driven cavity flow. The solver features a parallel computing ability based on the velocity space decomposition, which is different from the physical space decomposition based approach provided by the OpenFOAM framework. The two decomposition approaches have been compared in both two and three dimensional cases. The parallel performance improves significantly using the newly implemented approach. A speed up by two orders of magnitudes has been observed using 256 cores on a small cluster.

  5. Effect of aqueous pH and electrolyte concentration on structure, stability and flow behavior of non-ionic surfactant based solid lipid nanoparticles.

    PubMed

    Choi, Kyeong-Ok; Aditya, N P; Ko, Sanghoon

    2014-03-15

    The effects of pH and electrolyte concentration on the structure evolution, polymorphism, flow behavior and stability of solid lipid nanoparticles (SLNs), stabilized by the food-grade non-ionic surfactant Tween 80, were investigated. Development of a lipid crystal was governed by thermodynamically stable β- and β'-subunits and relative crystallinity decreased with increasing pH and electrolyte concentration. Aqueous stability and dispersibility increased with increasing pH and decreased with increasing electrolyte concentration. Flow behavior of the SLNs suspension was affected by the electrolyte concentration. However, the pH of the aqueous surfactant medium has not shown any effect on the flow behavior. From the results, it is clear that the pH and electrolyte concentration are among the potential factors which determines the stability and release properties of entrapped materials from SLNs. Copyright © 2013 Elsevier Ltd. All rights reserved.

  6. A Flow-Through High-Pressure Electrical Conductance Cell for Determining of Ion Association of Aqueous Electrolyte Solutions at High Temperature and Pressure

    SciTech Connect

    Bianchi, H.; Ho, P.C.; Palmer, D.A.; Wood, R.H.

    1999-09-12

    A flow-through high-pressure electrical conductance cell was designed and constructed to measure limiting molar conductances and ion association constants of dilute aqueous solutions with high precision at high temperatures and pressures. The basic concept of the cell employs the principle developed at the University of Delaware in 1995, but overall targets higher temperatures (to 600 C) and pressures (to 300 MPa). At present the cell has been tested by measuring aqueous NaCl and LiOH solutions (10{sup {minus}3} to 10{sup {minus}5} mol.kg{sup {minus}1}) to 405 C and 33 MPa with good results.

  7. Electrically conductive rigid polyurethane foam

    DOEpatents

    Neet, T.E.; Spieker, D.A.

    1983-12-08

    A rigid, moldable polyurethane foam comprises about 2 to 10 weight percent, based on the total foam weight, of a carbon black which is CONDUCTEX CC-40-220 or CONDUCTEX SC, whereby the rigid polyurethane foam is electrically conductive and has essentially the same mechanical properties as the same foam without carbon black added.

  8. Electrically conductive rigid polyurethane foam

    DOEpatents

    Neet, Thomas E.; Spieker, David A.

    1985-03-19

    A rigid, polyurethane foam comprises about 2-10 weight percent, based on the total foam weight, of a carbon black which is CONDUCTEX CC-40-220 or CONDUCTEX SC, whereby the rigid polyurethane foam is electrically conductive and has essentially the same mechanical properties as the same foam without carbon black added.

  9. Influence of Flexibility and Dimensions of Nanocelluloses on the Flow Properties of Their Aqueous Dispersions.

    PubMed

    Tanaka, Reina; Saito, Tsuguyuki; Hondo, Hiromasa; Isogai, Akira

    2015-07-13

    We report that the intrinsic viscosity [η] of nanocellulose dispersions can be solely expressed as a function of the aspect ratio p of the nanocellulose. Both short rod-like nanocrystalline and long spaghetti-like nanofibrillated celluloses were prepared as dispersions in water. The influence of the flexibility and dimensions of the nanocelluloses on the flow properties of their dispersions was investigated by experimental and theoretical approaches using seven nanocellulose samples with different widths (2.6-14.4 nm) and aspect ratios (23-376). As the aspect ratio of a nanocellulose increases, it becomes more flexible, and its dispersion has higher viscosity. Irrespective of the flexibility and dimensions of these nanocelluloses, the relationship between [η] and p was ρ[η] = 0.15 × p(1.9), where ρ is the density of the nanocellulose.

  10. Interfacial Stabilization of Fiber-Laden Foams with Carboxymethylated Lignin toward Strong Nonwoven Networks.

    PubMed

    Li, Shuai; Xiang, Wenchao; Järvinen, Marjo; Lappalainen, Timo; Salminen, Kristian; Rojas, Orlando J

    2016-08-03

    Wet foams were produced via agitation and compressed air bubbling of aqueous solutions of carboxymethylated lignin (CML). Bubble size and distribution were assessed in situ via optical microscopy. Foamability, bubble collapse rate, and foam stability (half-life time) were analyzed as a function of CML concentration, temperature, pH, and air content. Dynamic changes of the CML liquid foam were monitored by light transmission and backscattering. Cellulosic fibers of different aspect ratios (long pine fibers and short birch fibers) were suspended under agitation by the liquid foams (0.6% CML in the aqueous phase) with an air (bubble) content as high as 75% in volume. Remarkably, the half-life time of fiber-laden CML foams was 10-fold higher than that of the corresponding fiber-free liquid foam. Such lignin-based foams were demonstrated, after dewatering, as a precursor for the synthesis of nonwoven, layered structures. The resulting fiber networks (paper), obtained here for the first time with lignin-based foams, were characterized for pore size distribution, lignin retention, morphology, and physical-mechanical properties (network formation quality, density, air permeability, surface roughness, and tensile and internal bond strengths). The results were compared against structures obtained from foams stabilized with an anionic surfactant (SDS) as well as those from foam-free, water-based web-laying. Remarkably, compared to SDS, the foam-formed materials produced with CML displayed better bonding and tensile strengths. Overall, CML-based foams were found to be suitable carriers of cellulosic fibers and have opened the possibility for integrating fully biobased systems in foam-forming. This is an emerging option to increase the effective solids content in the system without compromising the quality of formed nonwoven materials while achieving reductions in water and energy consumption.

  11. Experiments for foam model development and validation.

    SciTech Connect

    Bourdon, Christopher Jay; Cote, Raymond O.; Moffat, Harry K.; Grillet, Anne Mary; Mahoney, James F.; Russick, Edward Mark; Adolf, Douglas Brian; Rao, Rekha Ranjana; Thompson, Kyle Richard; Kraynik, Andrew Michael; Castaneda, Jaime N.; Brotherton, Christopher M.; Mondy, Lisa Ann; Gorby, Allen D.

    2008-09-01

    A series of experiments has been performed to allow observation of the foaming process and the collection of temperature, rise rate, and microstructural data. Microfocus video is used in conjunction with particle image velocimetry (PIV) to elucidate the boundary condition at the wall. Rheology, reaction kinetics and density measurements complement the flow visualization. X-ray computed tomography (CT) is used to examine the cured foams to determine density gradients. These data provide input to a continuum level finite element model of the blowing process.

  12. Batch foam fractionation of kudzu (Pueraria lobata) vine retting solution.

    PubMed

    Eiamwat, J; Loha, V; Prokop, A; Tanner, R D

    1998-01-01

    The aqueous protein solution from kudzu (Pueraria lobata) vine retting broth, without the addition of other surfactants, was foam-fractionated in a vertical tubular column with multiple sampling ports. Time-varying trajectories of the total protein levels were determined to describe the protein behavior at six positions along the 1-m column. The lowest two trajectories of this batch process represented a loss of proteins from the bulk liquid and tended to merge and decay together in time; the other trajectories displayed a gain in proteins in the foam phase. These upper column port protein concentration trajectories generally increased in time up to 45 mm, followed by a decrease, reflecting the removal of proteins from the column ports. The foam became dryer as it passed up the column to the top port. The protein concentration was about 5-8x higher in the top port foam than in the initial bulk solution, mainly as a result of liquid drainage from the foam along the column axis. This concentration increase in the collected foam was dependent on the initial pH of the bulk solution. The mol-wt profile of the proteins in the concentrated foam effluent was determined by one-dimensional gel electrophoresis. An analysis of the gel electropherograms indicated that the most abundant proteins could be cellulases and pectinases.

  13. Domain growth kinetics in stratifying foam films

    NASA Astrophysics Data System (ADS)

    Zhang, Yiran; Sharma, Vivek

    2015-11-01

    Baking bread, brewing cappuccino, pouring beer, washing dishes, shaving, shampooing, whipping eggs and blowing bubbles all involve creation of aqueous foam films. Typical foam films consist of two surfactant-laden surfaces that are ~ 5 nm - 10 micron apart. Sandwiched between these interfacial layers is a fluid that drains primarily under the influence of viscous and interfacial forces, including disjoining pressure. Interestingly, a layered ordering of micelles inside the foam films (thickness <100 nm) leads to a stepwise thinning phenomena called stratification, which results in a thickness-dependent variation in reflected light intensity, visualized as progressively darker shades of gray. Thinner, darker domains spontaneously grow within foam films. We show that the domain expansion dynamics exhibit two distinct growth regimes with characteristic scaling laws. Though several studies have focused on the expansion dynamics of isolated domains that exhibit a diffusion-like scaling, the change in expansion kinetics observed after domains contact with the Plateau border has not been reported and analyzed before.

  14. Coupled elasticity in soft solid foams

    NASA Astrophysics Data System (ADS)

    Gorlier, F.; Khidas, Y.; Pitois, O.

    2017-09-01

    Elasticity of soft materials can be greatly influenced by the presence of air bubbles. Such a capillary effect is expected for a wide range of materials, from polymer gels to concentrated emulsions and colloidal suspensions. Whereas experimental results and theory exist for describing the elasto-capillary behavior of bubbly materials (i.e. with moderate gas volume fractions), foamy systems still require a dedicated study in order to increase our understanding of elasticity in aerated materials over the full range of gas volume fractions. Here we elaborate well-controlled foams with concentrated emulsion and we measure their shear elastic modulus as a function of gas fraction, bubble size and elastic modulus of the emulsion. Such complex foams possess the elastic features of both the bubble assembly and the interstitial matrix. Moreover, their elastic modulus is shown to be governed by two parameters, namely the gas volume fraction and the elasto-capillary number, defined as the ratio of the emulsion modulus with the bubble capillary pressure. We connect our results for foams with existing data for bubbly systems and we provide a general view for the effect of gas bubbles in soft elastic media. Finally, we suggest that our results could be useful for estimating the shear modulus of aqueous foams and emulsions with multimodal size distributions.

  15. Foam For Filtering

    NASA Technical Reports Server (NTRS)

    1978-01-01

    Like nature's honeycomb, foam is a structure of many-sided cells, apparently solid but actually only three percent material and 97 percent air. Foam is made by a heat-producing chemical reaction which expands a plastic material in a manner somewhat akin to the heat-induced rising of a loaf of bread. The resulting structure of interconnected cells is flexible yet strong and extremely versatile in applicati6n. Foam can, for example, be a sound absorber in one form, while in another it allows sound to pass through it. It can be a very soft powder puff material and at the same time a highly abrasive scrubber. A sampling of foam uses includes stereo speaker grilles, applying postage meter ink, filtering lawnmower carburetor air; deadening noise in trucks and tractors, applying cosmetics, releasing fabric softener and antistatic agents in home clothes dryers, painting, filtering factory heating and ventilating systems, shining shoes, polishing cars, sponge-mopping floors, acting as pre-operative surgical scrubbers-the list is virtually limitless. The process by which foam is made produces "windows," thin plastic membranes connecting the cell walls. Windowed foam is used in many applications but for certain others-filtering, for example-it is desirable to have a completely open network. Scott Paper Company's Foam Division, Chester, Pennsylvania, improved a patented method of "removing the windows," to create an open structure that affords special utility in filtering applications. NASA technology contributed to Scott's improvement.

  16. Simple and rapid hydrogenation of p-nitrophenol with aqueous formic acid in catalytic flow reactors

    PubMed Central

    Kawasaki, Shin-ichiro; Suzuki, Akira

    2013-01-01

    Summary The inner surface of a metallic tube (i.d. 0.5 mm) was coated with a palladium (Pd)-based thin metallic layer by flow electroless plating. Simultaneous plating of Pd and silver (Ag) from their electroless-plating solution produced a mixed distributed bimetallic layer. Preferential acid leaching of Ag from the Pd–Ag layer produced a porous Pd surface. Hydrogenation of p-nitrophenol was examined in the presence of formic acid simply by passing the reaction solution through the catalytic tubular reactors. p-Aminophenol was the sole product of hydrogenation. No side reaction occurred. Reaction conversion with respect to p-nitrophenol was dependent on the catalyst layer type, the temperature, pH, amount of formic acid, and the residence time. A porous and oxidized Pd (PdO) surface gave the best reaction conversion among the catalytic reactors examined. p-Nitrophenol was converted quantitatively to p-aminophenol within 15 s of residence time in the porous PdO reactor at 40 °C. Evolution of carbon dioxide (CO2) was observed during the reaction, although hydrogen (H2) was not found in the gas phase. Dehydrogenation of formic acid did not occur to any practical degree in the absence of p-nitrophenol. Consequently, the nitro group was reduced via hydrogen transfer from formic acid to p-nitrophenol and not by hydrogen generated by dehydrogenation of formic acid. PMID:23843908

  17. Simple and rapid hydrogenation of p-nitrophenol with aqueous formic acid in catalytic flow reactors.

    PubMed

    Javaid, Rahat; Kawasaki, Shin-Ichiro; Suzuki, Akira; Suzuki, Toshishige M

    2013-01-01

    The inner surface of a metallic tube (i.d. 0.5 mm) was coated with a palladium (Pd)-based thin metallic layer by flow electroless plating. Simultaneous plating of Pd and silver (Ag) from their electroless-plating solution produced a mixed distributed bimetallic layer. Preferential acid leaching of Ag from the Pd-Ag layer produced a porous Pd surface. Hydrogenation of p-nitrophenol was examined in the presence of formic acid simply by passing the reaction solution through the catalytic tubular reactors. p-Aminophenol was the sole product of hydrogenation. No side reaction occurred. Reaction conversion with respect to p-nitrophenol was dependent on the catalyst layer type, the temperature, pH, amount of formic acid, and the residence time. A porous and oxidized Pd (PdO) surface gave the best reaction conversion among the catalytic reactors examined. p-Nitrophenol was converted quantitatively to p-aminophenol within 15 s of residence time in the porous PdO reactor at 40 °C. Evolution of carbon dioxide (CO2) was observed during the reaction, although hydrogen (H2) was not found in the gas phase. Dehydrogenation of formic acid did not occur to any practical degree in the absence of p-nitrophenol. Consequently, the nitro group was reduced via hydrogen transfer from formic acid to p-nitrophenol and not by hydrogen generated by dehydrogenation of formic acid.

  18. Low density microcellular foams

    DOEpatents

    Aubert, J.H.; Clough, R.L.; Curro, J.G.; Quintana, C.A.; Russick, E.M.; Shaw, M.T.

    1985-10-02

    Low density, microporous polymer foams are provided by a process which comprises forming a solution of polymer and a suitable solvent followed by rapid cooling of the solution to form a phase-separated system and freeze the phase-separated system. The phase-separated system comprises a polymer phase and a solvent phase, each of which is substantially continuous within the other. The morphology of the polymer phase prior to and subsequent to freezing determine the morphology of the resultant foam. Both isotropic and anisotropic foams can be produced. If isotropic foams are produced, the polymer and solvent are tailored such that the solution spontaneously phase-separates prior to the point at which any component freezes. The morphology of the resultant polymer phase determines the morphology of the reusltant foam and the morphology of the polymer phase is retained by cooling the system at a rate sufficient to freeze one or both components of the system before a change in morphology can occur. Anisotropic foams are produced by forming a solution of polymer and solvent that will not phase separate prior to freezing of one or both components of the solution. In such a process, the solvent typically freezes before phase separation occurs. The morphology of the resultant frozen two-phase system determines the morphology of the resultant foam. The process involves subjecting the solution to essentially one-dimensional cooling. Foams having a density of less than 0.1 g/cc and a uniform cell size of less than 10 ..mu..m and a volume such that the foams have a length greater than 1 cm are provided.

  19. Low density microcellular foams

    DOEpatents

    Aubert, James H.; Clough, Roger L.; Curro, John G.; Quintana, Carlos A.; Russick, Edward M.; Shaw, Montgomery T.

    1987-01-01

    Low density, microporous polymer foams are provided by a process which comprises forming a solution of polymer and a suitable solvent followed by rapid cooling of the solution to form a phase-separated system and freeze the phase-separated system. The phase-separated system comprises a polymer phase and a solvent phase, each of which is substantially continuous within the other. The morphology of the polymer phase prior to and subsequent to freezing determine the morphology of the resultant foam. Both isotropic and anisotropic foams can be produced. If isotropic foams are produced, the polymer and solvent are tailored such that the solution spontaneously phase-separates prior to the point at which any component freezes. The morphology of the resultant polymer phase determines the morphology of the resultant foam and the morphology of the polymer phase is retained by cooling the system at a rate sufficient to freeze one or both components of the system before a change in morphology can occur. Anisotropic foams are produced by forming a solution of polymer and solvent that will not phase separate prior to freezing of one or both components of the solution. In such a process, the solvent typically freezes before phase separation occurs. The morphology of the resultant frozen two-phase system determines the morphology of the resultant foam. The process involves subjecting the solution to essentially one-dimensional cooling. Means for subjecting such a solvent to one-dimensional cooling are also provided. Foams having a density of less than 0.1 g/cc and a uniform cell size of less than 10 .mu.m and a volume such that the foams have a length greater than 1 cm are provided.

  20. Transport of CO2 foam stabilized with engineered nanoparticles

    NASA Astrophysics Data System (ADS)

    Prigiobbe, V.; Worthen, A. J.; Aroonsri, A.; Huh, C.; Bryant, S. L.

    2014-12-01

    Foam injection into the subsurface is performed to improve gas control mobility for residual oil extraction in, e.g., enhanced oil recovery and contaminated site remediation. Foam improves the gas mobility control as the gas viscosity is increased through its dispersion into a liquid phase. Finer the bubbles the lower the gas apparent viscosity (or foam viscosity) and the better is the sweep efficiency of the residual oil. A chemical surfactant adsorbed at the gas-liquid interface is generally used to maintain an optimal foam texture (number of bubbles for unit volume) however it can be desorbed making the foam coarser. Here, we present an experimental and modeling study on the effect of nanoparticles on foam stability. Nanoparticles are adsorbed onto the bubble interface irreversibly and therefore they are expected to keep the desired texture of the foam for the entire time of its application. In this study, we use silica nanoparticles in conjunction with a surfactant to study the transport behavior of a CO2 foam in a porous medium. Experiments were performed using a glass-bead pack and Boise sandstone with foam quality (fg) 0.1-0.9 until steady-state. Foam flow was described by a mechanistic population balance model coupled with the fractional flow equation and constitutive equations for foam generation and destruction based on lamella division and bubble coalescence mechanisms, respectively. In order to minimize the uncertainty, model parameters were estimated by combining experimental data of pressure gradient during steady-state and transient. Experiments and theory agree very well and the overall results show a significant increase in foam texture and stability when nanoparticles and surfactant are added to a foam flow in a low permeability porous medium. Data from tests with various nanoparticle concentrations (cn) show that gas apparent viscosity changes with fg and cn. But its optimal value does not vary with cn and it is already attained at fg equal to 0

  1. Photo-Fenton degradation of the insecticide esfenvalerate in aqueous medium using a recirculation flow-through UV photoreactor.

    PubMed

    Colombo, Renata; Ferreira, Tanare C R; Alves, Suellen A; Lanza, Marcos R V

    2011-12-30

    The aim of the study was to evaluate the efficiencies of photo-Fenton (Fe(2+)) and (Fe(3+)) processes in the degradation of high-concentrations of esfenvalerate (in the form of aqueous emulsion of a commercial formulation) using a recirculation flow-through photoreactor irradiated with UV light from a 15 W lamp (254 nm emission peak). The results obtained using a basic photo-Fenton (Fe(2+)) reaction (esfenvalerate 17 mg L(-1); ferrous sulphate 1 mM; hydrogen peroxide 25 mM; pH 2.5) were compared with those acquired when ferrioxalate (1, 3 or 5 mM) served as the iron source. Degradation of the active component of the commercial formulation was significantly greater, and the rate of oxidation more rapid, using a photo-Fenton (Fe(3+)) process compared with its Fe(2+) counterpart. The most efficient degradation of the insecticide (75% in 180 min) was achieved with a reaction mixture containing 5mM ferrioxalate. However, under the same experimental conditions, degradation of pure esfenvalerate preceded much faster (99% in 60 min) and was 100% complete within 180 min reaction time.

  2. Effects of an Aqueous Extract of Dangguijagyagsan on Serum Lipid Levels and Blood Flow Improvement in Ovariectomized Rats

    PubMed Central

    Park, In Sil; Lee, Hye Won; Ko, Byoung Seob

    2014-01-01

    Dangguijagyagsan (DJS), a traditional herbal prescription, has long been used to treat menopause-related symptoms. We identified the cardioprotective effects of an aqueous extract of DJS using an ovariectomized (OVX) and ferric chloride- (FeCl-) induced carotid thrombosis rat model. Female Sprague-Dawley (SD) rats were ovariectomized or Sham-operated (Sham-control). The ovariectomized rats were divided into three groups: OVX with saline (OVX-control), aspirin 30 mg/kg/day (OVX-ASA), and DJS 100 mg/kg/day (OVX-DJS). The treatments were administered for 5 weeks. Then, blood samples were collected to analyze the serum lipid levels and platelet aggregation. The topical application of 40% FeCl3 induced intravascular thrombosis, which was used to test thrombotic occlusion and for histological examination. Body weight and the levels of total cholesterol (TC), triglyceride (TG), and LDL-cholesterol (LDL-C) increased in the OVX rats. These effects were reduced by ASA and DJS treatment. In addition, ASA and DJS treatment significantly inhibited platelet aggregation. These treatments also increased time to occlusion and decreased both thrombus size and the presence of collagen fibers in surrounding vessel walls compared with the Sham-control and OVX-control groups. These results suggest that DJS has beneficial effects in terms of preventing cardiovascular disease in menopausal woman because it can reduce the serum lipid levels and improve blood flow by inhibiting platelet aggregation and thrombus formation. PMID:25276217

  3. The foaming of lavas

    NASA Technical Reports Server (NTRS)

    Okeefe, J. A.; Walton, W.

    1976-01-01

    Foaming is of great practical and theoretical significance for volcanic processes on the earth, the moon, and perhaps the meteorite parent bodies. The theory of foams agrees with steelmaking experience to indicate that their presence depends on the existence of solutes in the lavas which reduce the surface tension, and are not saturated. These solutes concentrate at the surface, and are called surfactants. The surfactant responsible for the formation of volcanic ash was not identified; it appears to be related to the oxygen partial pressure above the lava. This fact may explain why lunar and meteoritic melts are not observed to foam. Experimental studies are needed to clarify the process.

  4. Foam encapsulated targets

    DOEpatents

    Nuckolls, John H.; Thiessen, Albert R.; Dahlbacka, Glen H.

    1983-01-01

    Foam encapsulated laser-fusion targets wherein a quantity of thermonuclear fuel is embedded in low density, microcellular foam which serves as an electron conduction channel for symmetrical implosion of the fuel by illumination of the target by one or more laser beams. The fuel, such as DT, is contained within a hollow shell constructed of glass, for example, with the foam having a cell size of preferably no greater than 2 .mu.m, a density of 0.065 to 0.6.times.10.sup.3 kg/m.sup.3, and external diameter of less than 200 .mu.m.

  5. Experimental Evaluation of Equivalent-Fluid Models for Melamine Foam

    NASA Technical Reports Server (NTRS)

    Allen, Albert R.; Schiller, Noah H.

    2016-01-01

    Melamine foam is a soft porous material commonly used in noise control applications. Many models exist to represent porous materials at various levels of fidelity. This work focuses on rigid frame equivalent fluid models, which represent the foam as a fluid with a complex speed of sound and density. There are several empirical models available to determine these frequency dependent parameters based on an estimate of the material flow resistivity. Alternatively, these properties can be experimentally educed using an impedance tube setup. Since vibroacoustic models are generally sensitive to these properties, this paper assesses the accuracy of several empirical models relative to impedance tube measurements collected with melamine foam samples. Diffuse field sound absorption measurements collected using large test articles in a laboratory are also compared with absorption predictions determined using model-based and measured foam properties. Melamine foam slabs of various thicknesses are considered.

  6. Permeability studies on 3D Ni foam/graphene composites

    NASA Astrophysics Data System (ADS)

    Yang, Zhuxian; Chen, Hongmei; Wang, Nannan; Xia, Yongde; Zhu, Yanqiu

    2017-09-01

    This study investigates the permeability of new 3D Ni foam/graphene composites (Ni foam covered with graphene) using compressed air, Ar and N2 as the probe gases. The results show that the introduction of graphene on the surface of Ni foam via in situ chemical vapour deposition is not detrimental to the permeability of the composites; on the contrary, in some cases it improves permeability. A modified Ergun-type correlation has been proposed, which represents very well the permeability of the Ni foam/graphene composites, especially at flow rates higher than 0.3 m s-1. Further studies show that graphene also helps to improve the thermal conductivity of the composite. These results suggest that the graphene involvement will make the Ni foam/graphene composite a good candidate for potential applications such as filters or heat exchangers suitable for working under harsh conditions such as at high temperatures, in corrosive environments, etc.

  7. Electroless plating of Ni thin films using foam of electrolyte

    NASA Astrophysics Data System (ADS)

    Furuhashi, Takahiro; Yamada, Yoshiyasu; Ichihara, Shoji; Takai, Akihiro; Usui, Hiroaki

    2016-02-01

    Electroless plating of Ni thin films was achieved in foam of electroplating solution in place of electroplating liquid. Commercial hypophosphite-based solution for Ni electroless plating was added with a surfactant of sulfuric acid monododecyl ester sodium salt (SDS) and bubbled with nitrogen gas to produce airy foam. Ni thin films were deposited by immersing iron substrates in the foam. Although stationary foam was inconvenient for electrodeposition by itself, film growth was enhanced by generating a flow of foam using substrate rotation and by adding SDS to a concentration of 0.1 to 0.3 wt %. No defects attributed to pinholes were observed on the film surface. This method was effective in reducing the net amount of plating solution necessary for film deposition.

  8. Visualization of the Crystallization in Foam Extrusion Process

    NASA Astrophysics Data System (ADS)

    Tabatabaei Naeini, Alireza

    In this study, crystal formation of polypropylene (PP) and poly lactic acid (PLA) in the presence of CO2 in foam extrusion process was investigated using a visualization chamber and a CCD camera. The role of pre-existing crystals on the foaming behavior of PP and PLA were studied by characterizing the foam morphology. Visualization results showed that crystals formed within the die before foaming and these crystals affect the cell nucleation behavior and expansion ratio of PP and PLA significantly. Due to the fast crystallization kinetics of PP, crystallinity should be optimum to achieve uniform cell structure with high cell density and high expansion ratio. In PLA, enhancement of crystallinity is crucial for getting foam with a high expansion ratio. It was also visualized that CO2 significantly suppresses the crystallization temperature in PP through the plasticization effect as well as its influence on flow induced crystallinity.

  9. Mixing insert for foam dispensing apparatus

    NASA Technical Reports Server (NTRS)

    Simpson, W. G. (Inventor)

    1976-01-01

    A device for mixing foam ingredients is described. The device comprises an arrangement of lands situated about a cylindrical elongated shaft-like member with each land having a slot. The slots of alternate lands are positioned 180 deg from each other so that as the ingredients flow through the mixing chamber they flow from adjacent one side of the housing to the other dividing as such passes around the shaft-like member.

  10. Volumetric requirements for foam and mist drilling operations

    SciTech Connect

    Okpobiri, G.A.; Ikoku, C.U.

    1986-02-01

    State-of-the-art foam and mist drilling suggests a need for predictive models for volumetric requirements that properly account for frictional losses caused by the solid phase in solids/foam slurry flow, settling velocities of such solids, and pressure drop across bit nozzles during foam flow. The objective of this paper is to fulfill this need. A model that predicts pressure drop across bit nozzles for foam and mist and minimum volumetric requirements for foam and mist drilling operations is presented. It accounts for the compressibility of foam but assumes negligible pressure losses resulting from friction and change in elevation and for the frictional losses caused by the solid phase, pressure drop across bit nozzles, and particle-settling velocity. This technique offers a high degree of flexibility in the selection of wellhead injection pressures and volumetric injection rates. Field application of this work can be accomplished by two primarily graphical methods that depend on compressor specification: variable-backpressure and constant-backpressure schedules. Charts are presented for 7.875- and 9.00-in. hole sizes, and for 0.500-, 0.75-, and 1.00-in. cutting sizes. Penetration rates range from 30 to 90 ft/hr. Results indicate that volumetric requirements increase with increasing hole size, depth, and particle size. Increases in penetration rate cause only minor increases in volumetric requirements. All foam-drilling and well-cleanout operations can be accomplished within the laminar flow region with adherence to 0.55 minimum bottomhole and 0.96 maximum annular foam quality. Annular backpressures greater than atmospheric pressure are needed to maintain a bottomhole foam quality of 0.55 or more while reaching reasonable depths. To maintain constant depth as backpressure increases, however, both wellhead injection pressure and gas injection rate must be increased, and liquid flow rate decreased.

  11. Graphite Foam Heat Exchangers for Thermal Management

    SciTech Connect

    Klett, J.W.

    2004-06-07

    better than the standard heat sinks. Next, work with evaporative cooling techniques, such as heat pipes, demonstrated some unique behavior with the foam that is not seen with standard wick materials. This was that as the thickness of the foam increased, the performance got better, where with standard wick materials, as the thickness increases, the performance decreases. This is yet to be completely explained. Last, the designs from the thermal model were used to fabricate a series of cold plates with the graphite foam and compare them to similar designs using high performance folded fin aluminum sinks (considered standard in the industry). It was shown that by corrugating the foam parallel to fluid flow, the pressure drop can be reduced significantly while maintaining the same heat transfer as that in the folded fin heat sink. In fact, the results show that the graphite foam heat sink can utilized 5% the pumping power as that required with the folded fin aluminum heat sink, yet remove the same amount of heat.

  12. Aging of clean foams

    NASA Astrophysics Data System (ADS)

    Weon, Byung Mook; Stewart, Peter S.

    2014-11-01

    Aging is an inevitable process in living systems. Here we show how clean foams age with time through sequential coalescence events: in particular, foam aging resembles biological aging. We measure population dynamics of bubbles in clean foams through numerical simulations with a bubble network model. We demonstrate that death rates of individual bubbles increase exponentially with time, independent on initial conditions, which is consistent with the Gompertz mortality law as usually found in biological aging. This consistency suggests that clean foams as far-from-equilibrium dissipative systems are useful to explore biological aging. This work (NRF-2013R1A22A04008115) was supported by Mid-career Researcher Program through NRF grant funded by the MEST.

  13. Mechanical Foam Remover

    NASA Technical Reports Server (NTRS)

    Streech, Neil

    1994-01-01

    Filter removes foam from soapy water stream discharged by primary phase separator of water-reclamation system. Uses no antifoam chemicals, contains no moving parts and requires no energy input other than small energy needed to pump water through filter.

  14. Hydrodynamics of foams

    NASA Astrophysics Data System (ADS)

    Karakashev, Stoyan I.

    2017-08-01

    This brief review article is devoted to all the aspects related to hydrodynamics of foams. For this reason, we focused at first on the methods for studying the basic structural units of the foams—the foam films (FF) and the Plateau borders (PB), thus reviewing the literature about their drainage. After this, we scrutinized in detail the Derjaguin's works on the electrostatic disjoining pressure along with its Langmuir's interpretation, the microscopic and macroscopic approaches in the theory of the van der Waals disjoining pressure, the DLVO theory, the steric disjoining pressure of de Gennes, and the more recent works on non-DLVO forces. The basic methods for studying of foam drainage are presented as well. Engineering and other applications of foam are reviewed as well. All these aspects are presented from retrospective and perspective viewpoints.

  15. Foam fracturing laboratory

    SciTech Connect

    Earl, R.B.; Wendroff, C.L.

    1983-10-01

    A new laboratory has been constructed with test equipment designed to expose foam fracturing fluids to test conditions simulating treatment conditions of shear, time, temperature and pressure during the tests. The goal for designing this laboratory was to simulate treating and downhole conditions as closely as possible and to determine fracturing foam properties under these conditions. This paper describes the design parameters and equipment in this unique laboratory.

  16. Ocean foam generation and modeling

    NASA Technical Reports Server (NTRS)

    Porter, R. A.; Bechis, K. P.

    1976-01-01

    A laboratory investigation was conducted to determine the physical and microwave properties of ocean foam. Special foam generators were designed and fabricated, using porous glass sheets, known as glass frits, as the principal element. The glass frit was sealed into a water-tight vertical box, a few centimeters from the bottom. Compressed air, applied to the lower chamber, created ocean foam from sea water lying on the frit. Foam heights of 30 cm were readily achieved, with relatively low air pressures. Special photographic techniques and analytical procedures were employed to determine foam bubble size distributions. In addition, the percentage water content of ocean foam was determined with the aid of a particulate sampling procedure. A glass frit foam generator, with pore diameters in the range 70 - 100 micrometers, produced foam with bubble distributions very similar to those found on the surface of natural ocean foam patches.

  17. Responsive foams for nanoparticle delivery.

    PubMed

    Tang, Christina; Xiao, Edward; Sinko, Patrick J; Szekely, Zoltan; Prud'homme, Robert K

    2015-09-01

    We have developed responsive foam systems for nanoparticle delivery. The foams are easy to make, stable at room temperature, and can be engineered to break in response to temperature or moisture. Temperature-responsive foams are based on the phase transition of long chain alcohols and could be produced using medical grade nitrous oxide as a propellant. These temperature-sensitive foams could be used for polyacrylic acid (PAA)-based nanoparticle delivery. We also discuss moisture-responsive foams made with soap pump dispensers. Polyethylene glycol (PEG)-based nanoparticles or PMMA latex nanoparticles were loaded into Tween 20 foams and the particle size was not affected by the foam formulation or foam break. Using biocompatible detergents, we anticipate this will be a versatile and simple approach to producing foams for nanoparticle delivery with many potential pharmaceutical and personal care applications. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Rigid molecular foams

    SciTech Connect

    Steckle, W.P. Jr.; Mitchell, M.A.; Aspen, P.G.

    1998-12-31

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Organic analogues to inorganic zeolites would be a significant step forward in engineered porous materials and would provide advantages in range, selectivity, tailorability, and processing. Rigid molecular foams or {open_quotes}organic zeolites{close_quotes} would not be crystalline materials and could be tailored over a broader range of pore sizes and volumes. A novel process for preparing hypercrosslinked polymeric foams has been developed via a Friedel-Crafts polycondensation reaction. A series of rigid hypercrosslinked foams have been prepared using simple rigid polyaromatic hydrocarbons including benzene, biphenyl, m-terphenyl, diphenylmethane, and polystyrene, with dichloroxylene (DCX) as the pore size. After drying the foams are robust and rigid. Densities of the resulting foams can range from 0.15 g/cc to 0.75 g/cc. Nitrogen adsorption studies have shown that by judiciously selecting monomers and the crosslinking agent along with the level of crosslinking and the cure time of the resulting gel, the pore size, pore size distribution, and the total surface area of the foam can be tailored. Surface areas range from 160 to 1,200 m{sup 2}/g with pore sizes ranging from 6 {angstrom} to 2,000 {angstrom}.

  19. Ultralight metal foams

    PubMed Central

    Jiang, Bin; He, Chunnian; Zhao, Naiqin; Nash, Philip; Shi, Chunsheng; Wang, Zejun

    2015-01-01

    Ultralight (<10 mg/cm3) cellular materials are desirable for thermal insulation; battery electrodes; catalyst supports; and acoustic, vibration, or shock energy damping. However, most of these ultralight materials, especially ultralight metal foams, are fabricated using either expensive materials or complicated procedures, which greatly limit their large-scale production and practical applications. Here we report a simple and versatile method to obtain ultralight monolithic metal foams. These materials are fabricated with a low-cost polymeric template and the method is based on the traditional silver mirror reaction and electroless plating. We have produced ultralight monolithic metal foams, such as silver, nickel, cobalt, and copper via this method. The resultant ultralight monolithic metal foams have remarkably low densities down to 7.4 mg/cm3 or 99.9% porosity. The metal foams have a long flat stress-train curve in compression tests and the densification strain εD of the Ni/Ag foam with a porosity of 99.8% can reach 82%. The plateau stress σpl was measured and found to be in agreement with the value predicted by the cellular solids theory. PMID:26349002

  20. Ultralight metal foams

    NASA Astrophysics Data System (ADS)

    Jiang, Bin; He, Chunnian; Zhao, Naiqin; Nash, Philip; Shi, Chunsheng; Wang, Zejun

    2015-09-01

    Ultralight (<10 mg/cm3) cellular materials are desirable for thermal insulation; battery electrodes; catalyst supports; and acoustic, vibration, or shock energy damping. However, most of these ultralight materials, especially ultralight metal foams, are fabricated using either expensive materials or complicated procedures, which greatly limit their large-scale production and practical applications. Here we report a simple and versatile method to obtain ultralight monolithic metal foams. These materials are fabricated with a low-cost polymeric template and the method is based on the traditional silver mirror reaction and electroless plating. We have produced ultralight monolithic metal foams, such as silver, nickel, cobalt, and copper via this method. The resultant ultralight monolithic metal foams have remarkably low densities down to 7.4 mg/cm3 or 99.9% porosity. The metal foams have a long flat stress-train curve in compression tests and the densification strain ɛD of the Ni/Ag foam with a porosity of 99.8% can reach 82%. The plateau stress σpl was measured and found to be in agreement with the value predicted by the cellular solids theory.

  1. Aromatic Polyimide Foam

    NASA Technical Reports Server (NTRS)

    Weiser, Erik S. (Inventor); St.Clair, Terry L. (Inventor); Echigo, Yoshiaki (Inventor); Kaneshiro, Hisayasu (Inventor)

    2000-01-01

    A mechanically undensified aromatic polyimide foam is made from an aromatic polyimide precursor solid residuum and has the following combination of properties: a density according to ASTM D-3574A of about 0.5 pounds/cu.ft to about 20 pounds/cu.ft; a compression strength according to ASTM D-3574C of about 1.5 psi to about 1500 psi; and a limiting oxygen index according to ASTM D-2863 of about 35% oxygen to about 75% oxygen at atmospheric pressure. The aromatic polyimide foam has no appreciable solid inorganic contaminants which are residues of inorganic blowing agents. The aromatic polyimide which constitutes the aromatic polyimide foam has a glass transition temperature (Tg) by differential scanning calorimetry of about 235 C to about 400 C; and a thermal stability of 0 to about 1% weight loss at 204 C as determined by thermogravinietric analysis (TGA). The aromatic polyimide foam has utility as foam insulation and as structural foam, for example, for aeronautical, aerospace and maritime applications.

  2. Ultralight metal foams.

    PubMed

    Jiang, Bin; He, Chunnian; Zhao, Naiqin; Nash, Philip; Shi, Chunsheng; Wang, Zejun

    2015-09-08

    Ultralight (<10 mg/cm3) cellular materials are desirable for thermal insulation; battery electrodes; catalyst supports; and acoustic, vibration, or shock energy damping. However, most of these ultralight materials, especially ultralight metal foams, are fabricated using either expensive materials or complicated procedures, which greatly limit their large-scale production and practical applications. Here we report a simple and versatile method to obtain ultralight monolithic metal foams. These materials are fabricated with a low-cost polymeric template and the method is based on the traditional silver mirror reaction and electroless plating. We have produced ultralight monolithic metal foams, such as silver, nickel, cobalt, and copper via this method. The resultant ultralight monolithic metal foams have remarkably low densities down to 7.4 mg/cm3 or 99.9% porosity. The metal foams have a long flat stress-train curve in compression tests and the densification strain εD of the Ni/Ag foam with a porosity of 99.8% can reach 82%. The plateau stress σpl was measured and found to be in agreement with the value predicted by the cellular solids theory.

  3. Aqueous humour concentrations of TGF-β, PLGF and FGF-1 and total retinal blood flow in patients with early non-proliferative diabetic retinopathy.

    PubMed

    Khuu, Lee-Anne; Tayyari, Faryan; Sivak, Jeremy M; Flanagan, John G; Singer, Shaun; Brent, Michael H; Huang, David; Tan, Ou; Hudson, Christopher

    2017-05-01

    To correlate angiogenic cytokines in the aqueous humour with total retinal blood flow in subjects with type 2 diabetes with non-proliferative diabetic retinopathy (NPDR). A total of 17 controls and 16 NPDR patients were recruited into the study. Aqueous humour was collected at the start of cataract surgery to assess the concentration of 14 angiogenic cytokines. Aqueous humour was analysed using the suspension array method. Six images were acquired to assess total retinal blood flow (TRBF) using the prototype RTVue(™) Doppler Fourier domain optical coherence tomography (Doppler FD-OCT) (Optovue, Inc., Fremont, CA) using a double circular scan protocol, 1 month postsurgery. At the same visit, forearm blood was collected to determine glycosylated haemoglobin (A1c). Transforming growth factor beta (TGF-β1, TGF-β2) and PLGF were increased while FGF-1 was reduced in NPDR compared to controls (Bonferroni corrected, p < 0.003 for all). Total retinal blood flow (TRBF) was significantly reduced in the NPDR group compared to controls (33.1 ± 9.9 versus 43.3 ± 5.3 μl/min, p = 0.002). Aqueous FGF-1 significantly correlated with TRBF in the NPDR group (r = 0.71, p = 0.01; r(2)  = 0.51). In a multiple regression analysis, A1c was found to be a significant predictor of aqueous TGF-β1 and FGF-1 (p = 0.018 and p = 0.020, respectively). Aqueous angiogenic cytokines (TGF-β1, TGF-β2 and PLGF) were elevated in conjunction with a reduction in TRBF in patients with NPDR compared to controls. Non-invasive measurement of TRBF may be useful for predicting aqueous FGF-1 levels and severity of vasculopathy in DR. © 2016 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

  4. The influence of scleral flap thickness, shape, and sutures on intraocular pressure (IOP) and aqueous humor flow direction in a trabeculectomy model

    PubMed Central

    Samsudin, Amir; Eames, Ian; Brocchini, Steve; Khaw, Peng Tee

    2015-01-01

    Purpose IOP and aqueous humor flow direction determined by the scleral flap immediately after trabeculectomy are critical determinants of the surgical outcome. We used a large-scale model to objectively measure the influence of flap thickness and shape, and suture number and position on pressure difference across the flap and flow of fluid underneath it. Methods The model exploits the principle of dynamic and geometric similarity, so while dimensions were up to 30× greater than actual, the flow had similar properties. Scleral flaps were represented by transparent 0.8 and 1.6 mm thick silicone sheets on an acrylic plate. Dyed 98% glycerine, representing the aqueous humor was pumped between the sheet and plate, and the equilibrium pressure measured with a pressure transducer. Image analysis based on the principle of dye dilution was performed using MATLAB software. Results The pressure drop across the flap was larger with thinner flaps, due to reduced rigidity and resistance. Doubling the surface area of flaps and reducing the number of sutures from 5 to 3 or 2 also resulted in larger pressure drops. Flow direction was affected mainly by suture number and position, it was less towards the sutures and more towards the nearest free edge of the flap. Posterior flow of aqueous humor was promoted by placing sutures along the sides while leaving the posterior edge free. Conclusion We demonstrate a new physical model which shows how changes in scleral flap thickness and shape, and suture number and position affect pressure and flow in a trabeculectomy. PMID:26561421

  5. Hyperbranched exopolysaccharide-enhanced foam properties of sodium fatty alcohol polyoxyethylene ether sulfate.

    PubMed

    Deng, Quanhua; Li, Haiping; Sun, Haoyang; Sun, Yange; Li, Ying

    2016-05-01

    The foam properties, such as the foamability, foam stability, drainage, coalescence and bulk rheology, of aqueous solutions containing an eco-friendly exopolysaccharide (EPS) secreted by a deep-sea mesophilic bacterium, Wangia profunda SM-A87, and an anionic surfactant, sodium fatty alcohol polyoxyethylene ether sulfate (AES), were studied. Both the foamability and foam stability of the EPS/AES solutions are considerably higher than those of single AES solutions, even at very low AES concentrations, although pure EPS solutions cannot foam. The improved foamability and foam stability arise from the formation of the EPS/AES complex via hydrogen bonds at the interfaces. The synergism between the EPS and AES decreases the surface tension, increases the interfacial elasticity and water-carrying capacity, and suppresses the coalescence and collapse of the foams. The EPS/AES foams are more salt-resistant than the AES foams. This work provides not only a new eco-friendly foam with great potential for use in enhanced oil recovery and health-care products but also useful guidance for designing other environmentally friendly foam systems that exhibit high performance. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. A Simple Approach to Characterize Gas-Aqueous Liquid Two-phase Flow Configuration Based on Discrete Solid-Liquid Contact Electrification

    PubMed Central

    Choi, Dongwhi; Lee, Donghyeon; Sung Kim, Dong

    2015-01-01

    In this study, we first suggest a simple approach to characterize configuration of gas-aqueous liquid two–phase flow based on discrete solid-liquid contact electrification, which is a newly defined concept as a sequential process of solid-liquid contact and successive detachment of the contact liquid from the solid surface. This approach exhibits several advantages such as simple operation, precise measurement, and cost-effectiveness. By using electric potential that is spontaneously generated by discrete solid–liquid contact electrification, the configurations of the gas-aqueous liquid two-phase flow such as size of a gas slug and flow rate are precisely characterized. According to the experimental and numerical analyses on parameters that affect electric potential, gas slugs have been verified to behave similarly to point electric charges when the measuring point of the electric potential is far enough from the gas slug. In addition, the configuration of the gas-aqueous liquid two-phase microfluidic system with multiple gas slugs is also characterized by using the presented approach. For a proof-of-concept demonstration of using the proposed approach in a self-triggered sensor, a gas slug detector with a counter system is developed to show its practicality and applicability. PMID:26462437

  7. A Simple Approach to Characterize Gas-Aqueous Liquid Two-phase Flow Configuration Based on Discrete Solid-Liquid Contact Electrification.

    PubMed

    Choi, Dongwhi; Lee, Donghyeon; Kim, Dong Sung

    2015-10-14

    In this study, we first suggest a simple approach to characterize configuration of gas-aqueous liquid two-phase flow based on discrete solid-liquid contact electrification, which is a newly defined concept as a sequential process of solid-liquid contact and successive detachment of the contact liquid from the solid surface. This approach exhibits several advantages such as simple operation, precise measurement, and cost-effectiveness. By using electric potential that is spontaneously generated by discrete solid-liquid contact electrification, the configurations of the gas-aqueous liquid two-phase flow such as size of a gas slug and flow rate are precisely characterized. According to the experimental and numerical analyses on parameters that affect electric potential, gas slugs have been verified to behave similarly to point electric charges when the measuring point of the electric potential is far enough from the gas slug. In addition, the configuration of the gas-aqueous liquid two-phase microfluidic system with multiple gas slugs is also characterized by using the presented approach. For a proof-of-concept demonstration of using the proposed approach in a self-triggered sensor, a gas slug detector with a counter system is developed to show its practicality and applicability.

  8. Rigid zeolite containing polyurethane foams

    DOEpatents

    Frost, Charles B.

    1985-01-01

    A closed cell rigid polyurethane foam has been prepared which contains up to about 60% by weight of molecular sieves capable of sorbing molecules with effective critical diameters of up to about 10 .ANG.. The molecular sieve component of the foam can be preloaded with catalysts or with reactive compounds that can be released upon activation of the foam to control and complete crosslinking after the foam is formed. The foam can also be loaded with water or other flame-retarding agents, after completion. Up to about 50% of the weight of the isocyanate component of the foam can be replaced by polyimide resin precursors for incorporation into the final polymeric network.

  9. Rigid zeolite containing polyurethane foams

    DOEpatents

    Frost, C.B.

    1984-05-18

    A closed cell rigid polyurethane foam has been prepared which contains up to about 60% by weight of molecular sieves capable of sorbing molecules with effective critical diameters of up to about 10 A. The molecular sieve component of the foam can be preloaded with catalysts or with reactive compounds that can be released upon activation of the foam to control and complete crosslinking after the foam is formed. The foam can also be loaded with water or other flame-retarding agents, after completion. Up to about 50% of the weight of the isocyanate component of the foam can be replaced by polyimide resin precursors for incorporation into the final polymeric network.

  10. Breathing air from protein foam.

    PubMed

    Ackermann, Douglas; Jewell, David N; Stedman, Matthew L; Burapatana, Vorakan; Atukorale, Prabhani V; Pinson, Michelle L; Wardle, Alison E; Zhu, Wenyan; Tanner, Robert D

    2003-01-01

    Protein foams can be used to extinguish fires. If foams are to be used to extinguish fires where people are present, such as in high-rise buildings or ships, then a method for allowing people to breathe in a foam-filled environment is needed. It is proposed that the air, used to create the foam be used for breathing. A canister that will break incoming air-filled foam has been designed for attachment to a standard gas mask, in order to provide breathable air to a trapped person. Preliminary results for the modified mask indicate feasibility of breathing air from air-filled protein foam.

  11. Ambient cure polyimide foams. [thermal resistant foams

    NASA Technical Reports Server (NTRS)

    Sawko, P. M.; Riccitiello, S. R.; Hamermesh, C. L. (Inventor)

    1978-01-01

    Flame and temperature resistant polyimide foams are prepared by the reaction of an aromatic dianhydride, (pyromellitic dianhydride) with an aromatic polyisocyanate, (polymethylene polyphenylisocyanate), in the presence of an inorganic acid and furfuryl alcohol. Usable acids include dilute sulfuric acid, dilute nitric acid, hydrochloric acid, polyphosphoric acid, and phosphoric acid, with the latter being preferred. The dianhydride and the isocyanate in about equimolar proportions constitute about 50% of the reaction mixture, the rest being made up with the acid and the alcohol in a ratio of about 1:10. An exothermic reaction between the acid and the alcohol provides the heat necessary for the other components to polymerize without recourse to external heat sources. The mixture can be sprayed on any surface to form polymeric foam in locations where the application of heat is not practical or possible, for instance, between walls or on mine tunnel surfaces.

  12. An aqueous, polymer-based redox-flow battery using non-corrosive, safe, and low-cost materials

    NASA Astrophysics Data System (ADS)

    Janoschka, Tobias; Martin, Norbert; Martin, Udo; Friebe, Christian; Morgenstern, Sabine; Hiller, Hannes; Hager, Martin D.; Schubert, Ulrich S.

    2015-11-01

    For renewable energy sources such as solar, wind, and hydroelectric to be effectively used in the grid of the future, flexible and scalable energy-storage solutions are necessary to mitigate output fluctuations. Redox-flow batteries (RFBs) were first built in the 1940s and are considered a promising large-scale energy-storage technology. A limited number of redox-active materials--mainly metal salts, corrosive halogens, and low-molar-mass organic compounds--have been investigated as active materials, and only a few membrane materials, such as Nafion, have been considered for RFBs. However, for systems that are intended for both domestic and large-scale use, safety and cost must be taken into account as well as energy density and capacity, particularly regarding long-term access to metal resources, which places limits on the lithium-ion-based and vanadium-based RFB development. Here we describe an affordable, safe, and scalable battery system, which uses organic polymers as the charge-storage material in combination with inexpensive dialysis membranes, which separate the anode and the cathode by the retention of the non-metallic, active (macro-molecular) species, and an aqueous sodium chloride solution as the electrolyte. This water- and polymer-based RFB has an energy density of 10 watt hours per litre, current densities of up to 100 milliamperes per square centimetre, and stable long-term cycling capability. The polymer-based RFB we present uses an environmentally benign sodium chloride solution and cheap, commercially available filter membranes instead of highly corrosive acid electrolytes and expensive membrane materials.

  13. An aqueous, polymer-based redox-flow battery using non-corrosive, safe, and low-cost materials.

    PubMed

    Janoschka, Tobias; Martin, Norbert; Martin, Udo; Friebe, Christian; Morgenstern, Sabine; Hiller, Hannes; Hager, Martin D; Schubert, Ulrich S

    2015-11-05

    For renewable energy sources such as solar, wind, and hydroelectric to be effectively used in the grid of the future, flexible and scalable energy-storage solutions are necessary to mitigate output fluctuations. Redox-flow batteries (RFBs) were first built in the 1940s and are considered a promising large-scale energy-storage technology. A limited number of redox-active materials--mainly metal salts, corrosive halogens, and low-molar-mass organic compounds--have been investigated as active materials, and only a few membrane materials, such as Nafion, have been considered for RFBs. However, for systems that are intended for both domestic and large-scale use, safety and cost must be taken into account as well as energy density and capacity, particularly regarding long-term access to metal resources, which places limits on the lithium-ion-based and vanadium-based RFB development. Here we describe an affordable, safe, and scalable battery system, which uses organic polymers as the charge-storage material in combination with inexpensive dialysis membranes, which separate the anode and the cathode by the retention of the non-metallic, active (macro-molecular) species, and an aqueous sodium chloride solution as the electrolyte. This water- and polymer-based RFB has an energy density of 10 watt hours per litre, current densities of up to 100 milliamperes per square centimetre, and stable long-term cycling capability. The polymer-based RFB we present uses an environmentally benign sodium chloride solution and cheap, commercially available filter membranes instead of highly corrosive acid electrolytes and expensive membrane materials.

  14. Novel method for investigation of two-phase flow in liquid feed direct methanol fuel cells using an aqueous H 2O 2 solution

    NASA Astrophysics Data System (ADS)

    Bewer, T.; Beckmann, T.; Dohle, H.; Mergel, J.; Stolten, D.

    One major issue in the development of direct methanol fuel cells (DMFC) is the management of the evolving CO 2 gas bubbles in the flow fields. These bubbles influence the flow distribution and therefore the power density of a cell. In this paper, a novel method for in situ production of bubbles in a test cell made of perspex is presented. The method is based on the decomposition of hydrogen peroxide solution (H 2O 2) to oxygen and water in aqueous media at the presence of a catalyst. By using an appropriate H 2O 2-concentration, the gas evolution rate can be set to same order of magnitude as in real direct methanol fuel cells. This approach allows the simulation of the flow distribution in DMFC by simple low-cost hardware. As no current conducting parts are needed, the whole dummy cell can be made of perspex to ensure a complete visibility of the flow. In a perspex flow cell with an active area of 600 cm 2, the flow homogeneity as a function of gas evolution rate, flow field and manifold design was investigated. Experiments show that splayed manifolds have a superior performance concerning flow uniformity compared to other designs. The use of grid structures as a flow field gives good bubble transport at all investigated current densities.

  15. A swirl generator case study for OpenFOAM

    NASA Astrophysics Data System (ADS)

    Petit, O.; Bosioc, A. I.; Nilsson, H.; Muntean, S.; Susan-Resiga, R. F.

    2010-08-01

    This work presents numerical results, using OpenFOAM, of the flow in the swirl flow generator test rig developed at Politehnica University of Timisoara, Romania. The work shows results computed by solving the unsteady Reynolds Averaged Navier Stokes equations. The unsteady method couples the rotating and stationary parts using a sliding grid interface based on a GGI formulation. Turbulence is modeled using the standard k-epsilon model, and block structured wall function ICEM-Hexa meshes are used. The numerical results are validated against experimental LDV results, and against designed velocity profiles. The investigation shows that OpenFOAM gives results that are comparable to the experimental and designed profiles. This case study was presented at the 5th OpenFOAM Workshop, held in Gothenburg, Sweden, as a tutorial on how to treat turbomachinery applications in OpenFOAM.

  16. Flow of Aqueous Humor

    MedlinePlus

    ... Deadlines & Guidelines Apply for a Grant Terms & Conditions Patent & Intellectual Property Policy For Current Awardees FAQs Our ... Deadlines & Guidelines Apply for a Grant Terms & Conditions Patent & Intellectual Property Policy For Current Awardees FAQs Our ...

  17. Flow of Aqueous Humor

    MedlinePlus

    ... FAQs Our Funding Philosophy Events Contact News & Media Science News Publications Multimedia Press Releases Newsletters Media Coverage Media ... FAQs Our Funding Philosophy Events Contact News & Media Science News Publications Multimedia Press Releases Newsletters Media Coverage Media ...

  18. Method of making metal-doped organic foam products

    DOEpatents

    Rinde, James A.

    1981-01-01

    Organic foams having a low density and very small cell size and method for roducing same in either a metal-loaded or unloaded (nonmetal loaded) form are described. Metal-doped foams are produced by soaking a polymer gel in an aqueous solution of desired metal salt, soaking the gel successively in a solvent series of decreasing polarity to remove water from the gel and replace it with a solvent of lower polarity with each successive solvent in the series being miscible with the solvents on each side and being saturated with the desired metal salt, and removing the last of the solvents from the gel to produce the desired metal-doped foam having desired density cell size, and metal loading. The unloaded or metal-doped foams can be utilized in a variety of applications requiring low density, small cell size foam. For example, rubidium-doped foam made in accordance with the invention has utility in special applications, such as in x-ray lasers.

  19. Simple surface foam application enhances bioremediation of oil-contaminated soil in cold conditions.

    PubMed

    Jeong, Seung-Woo; Jeong, Jongshin; Kim, Jaisoo

    2015-04-09

    Landfarming of oil-contaminated soil is ineffective at low temperatures, because the number and activity of micro-organisms declines. This study presents a simple and versatile technique for bioremediation of diesel-contaminated soil, which involves spraying foam on the soil surface without additional works such as tilling, or supply of water and air. Surfactant foam containing psychrophilic oil-degrading microbes and nutrients was sprayed twice daily over diesel-contaminated soil at 6 °C. Removal efficiencies in total petroleum hydrocarbon (TPH) at 30 days were 46.3% for landfarming and 73.7% for foam-spraying. The first-order kinetic biodegradation rates for landfarming and foam-spraying were calculated as 0.019 d(-1) and 0.044 d(-1), respectively. Foam acted as an insulating medium, keeping the soil 2 °C warmer than ambient air. Sprayed foam was slowly converted to aqueous solution within 10-12h and infiltrated the soil, providing microbes, nutrients, water, and air for bioaugmentation. Furthermore, surfactant present in the aqueous solution accelerated the dissolution of oil from the soil, resulting in readily biodegradable aqueous form. Significant reductions in hydrocarbon concentration were simultaneously observed in both semi-volatile and non-volatile fractions. As the initial soil TPH concentration increased, the TPH removal rate of the foam-spraying method also increased. Copyright © 2014 Elsevier B.V. All rights reserved.

  20. Foam Delivery of Calcium Polysulfide to Vadose Zone for Chromium-VI Immobilization: A Laboratory Evaluation

    SciTech Connect

    Zhong, Lirong; Qafoku, Nikolla; Szecsody, James E.; Dresel, P. Evan; Zhang, Z. F.

    2009-09-13

    The delivery of calcium polysulfide (CPS) to the vadose zone using foam and the immobilization of hexavalent chromium [Cr(VI)] via reduction by the foam-delivered CPS was studied in a series of batch and column experiments. Batch tests were conducted to select the CPS-surfactant foam-generating solutions, to determine the solution foamibility and the reducing potential of CPS-containing foams, and to study the influence of foam quality, surfactant concentration, and CPS concentration on foam stability. Based on the results of the batch experiments, a foaming surfactant-CPS mixture was selected and a system was designed and constructed to generate and deliver foams with high reducing potential and stable enough to be successfully used Cr(VI) immobilization laboratory tests. Column experiments were conducted to test the delivery of the CPS-foam mixtures under conditions similar to field vadose zone, to determine the transport-controlled rate and extent of Cr(VI) immobilization using this novel technology, and to compare the results with those obtained from water-based CPS delivery. Soil reduction was observed in all column tests where CPS was delivered by foam flushing. The massive mobilization of aqueous Cr(VI) which occurred in water-based CPS delivery column experiments was remarkably minimized in the foam-based CPS delivery column experiments, resulting in significant Cr(VI) in-situ immobilization. The results confirmed that foam injection can be successfully used for CPS delivery and Cr(VI) immobilization via reduction in contaminated vadose zones. Due to its advantage over water-based injection, the foam delivery technology can also be for the delivery of other remedial amendments, such as citrate, acetate, and polyphosphate to promote bio-reduction of redox-sensitive contaminants or contaminant precipitation and co-precipitation.

  1. Foam drilling and workover in high temperature wells

    SciTech Connect

    Pye, D.S.; Fischer, P.W.

    1980-05-06

    A method is described for conducting foam drilling and workover operations in a borehole penetrating a subterranean reservoir, particularly a high-temperature reservoir such as a geothermal reservoir. The method employs an aqueous foaming solution of 0.08 to 1.0% by weight of an amphoteric betaine, 0.02 to 0.4% by weight of a salt of a linear aliphatic or alkyl aryl hydrocarbon sulfonate and, optionally, from 0.03 to 3.5% by weight unneutralized ammonia. 19 claims.

  2. Low density metal hydride foams

    DOEpatents

    Maienschein, Jon L.; Barry, Patrick E.

    1991-01-01

    Disclosed is a low density foam having a porosity of from 0 to 98% and a density less than about 0.67 gm/cc, prepared by heating a mixture of powered lithium hydride and beryllium hydride in an inert atmosphere at a temperature ranging from about 455 to about 490 K for a period of time sufficient to cause foaming of said mixture, and cooling the foam thus produced. Also disclosed is the process of making the foam.

  3. Foam Insulation for Cryogenic Flowlines

    NASA Technical Reports Server (NTRS)

    Sonju, T. R.; Carbone, R. L.; Oves, R. E.

    1985-01-01

    Welded stainless-steel vacuum jackets on cryogenic ducts replaced by plastic foam-insulation jackets that weigh 12 percent less. Foam insulation has 85 percent of insulating ability of stainless-steel jacketing enclosing vacuum of 10 microns of mercury. Foam insulation easier to install than vacuum jacket. Moreover, foam less sensitive to damage and requires minimal maintenance. Resists vibration and expected to have service life of at least 10 years.

  4. Asymmetric Flow-Field Flow Fractionation (AF4) of Aqueous C60 Aggregates with Dynamic Light Scattering Size and LC-MS

    EPA Science Inventory

    Current methods for the size determination of nanomaterials in aqueous suspension include dynamic or static light scattering and electron or atomic force microscopy techniques. Light scattering techniques are limited by poor resolution and the scattering intensity dependence on p...

  5. Asymmetric Flow-Field Flow Fractionation (AF4) of Aqueous C60 Aggregates with Dynamic Light Scattering Size and LC-MS

    EPA Science Inventory

    Current methods for the size determination of nanomaterials in aqueous suspension include dynamic or static light scattering and electron or atomic force microscopy techniques. Light scattering techniques are limited by poor resolution and the scattering intensity dependence on p...

  6. A flow-through passive dosing system for continuously supplying aqueous solutions of hydrophobic chemicals to bioconcentration and aquatic toxicity tests.

    PubMed

    Adolfsson-Erici, Margaretha; Åkerman, Gun; Jahnke, Annika; Mayer, Philipp; McLachlan, Michael S

    2012-02-01

    A continuous supply of water with defined stable concentrations of hydrophobic chemicals is a requirement in a range of laboratory tests such as the OECD 305 protocol for determining the bioconcentration factor in fish. Satisfying this requirement continues to be a challenge, particularly for hydrophobic chemicals. Here we present a novel solution based on equilibrium passive dosing. It employs a commercially available unit consisting of ~16000 polydimethylsiloxane (PDMS) tubes connected to two manifolds. The chemicals are loaded into the unit by repeatedly perfusing it with a methanol solution of the substances that is progressively diluted with water. Thereafter the unit is perfused with water and the chemicals partition from the unit into the water. The system was tested with nine chemicals with logK(OW) ranging from 4.1 to 6.3. The aqueous concentrations generated were shown to be largely independent of the water flow rate, and the unit to unit reproducibility was within a factor of ~2. In continuous flow experiments the aqueous concentrations of most of the study chemicals remained constant over 8d. A model was assembled that allows prediction of the operating characteristics of the system from the logK(OW) or PDMS/water partition coefficient of the chemical. The system is a simple, safe, predictable and flexible tool that generates stable aqueous concentrations of hydrophobic chemicals.

  7. Thermal-hydraulic performance of metal foam heat exchangers under dry operating conditions

    DOE PAGES

    Nawaz, Kashif; Bock, Jessica; Jacobi, Anthony M.

    2017-03-14

    High porosity metal foams with novel thermal, mechanical, electrical, and acoustic properties are being more widely adopted for application. Due to their large surface-area-to-volume ratio and complex structure which induces better fluid mixing, boundary layer restarting and wake destruction, they hold promise for heat transfer applications. In this study, the thermal-hydraulic performance of open-cell aluminum metal foam heat exchanger has been evaluated. The impact of flow conditions and metal foam geometry on the heat transfer coefficient and gradient have been investigated. Metal foam heat exchanger with same geometry (face area, flow depth and fin dimensions) consisting of four different typemore » of metal foams have been built for the study. Experiments are conducted in a closed-loop wind tunnel at different flow rate under dry operating condition. Metal foams with a smaller pore size (40 PPI) have a larger heat transfer coefficient compared to foams with a larger pore size (5 PPI). However, foams with larger pores result in relatively smaller pressure gradients. Current thermal-hydraulic modeling practices have been reviewed and potential issues have been identified. Permeability and inertia coefficients are determined and compared to data reported in open literature. Finally, on the basis of the new experimental results, correlations are developed relating the foam characteristics and flow conditions through the friction factor f and the Colburn j factor.« less

  8. Ambient curing fire resistant foams

    NASA Technical Reports Server (NTRS)

    Hamermesh, C. L.; Hogenson, P. A.; Tung, C. Y.; Sawko, P. M.; Riccitiello, S. R.

    1979-01-01

    The feasibility of development of an ambient curing foam is described. The thermal stability and flame spread index of the foams were found to be comparable to those of the high-temperature cured polyimide foams by Monsanto two-foot tunnel test and NASA T-3 Fire test. Adaptation of the material to spray in place applications is described

  9. Ambient curing fire resistant foams

    NASA Technical Reports Server (NTRS)

    Hamermesh, C. L.; Hogenson, P. A.; Tung, C. Y.; Sawko, P. M.; Riccitiello, S. R.

    1979-01-01

    The feasibility of development of an ambient curing foam is described. The thermal stability and flame spread index of the foams were found to be comparable to those of the high-temperature cured polyimide foams by Monsanto two-foot tunnel test and NASA T-3 Fire test. Adaptation of the material to spray in place applications is described

  10. Influence of filler selection on twin screw foam granulation.

    PubMed

    Rocca, K E; Weatherley, S; Sheskey, P J; Thompson, M R

    2015-01-01

    The influence of filler selection in wet granulation was studied for the novel case where the binder is delivered as an unstable, semi-rigid aqueous foam to an extrusion process. The work primarily examined the impact of differing concentrations of microcrystalline cellulose (Avicel PH® 101) in a formulation with spray-dried α-lactose monohydrate (Flowlac® 100) in regards to wetting and granule nucleation for this relatively new technique known as continuous foam granulation. Foam stability was varied within the work to change its drainage and coarsening behavior atop these powder excipients, by use of different foamable binding agents (METHOCEL™ F4 PLV and METHOCEL™ Premium VLV) as well as by adjusting the foam quality. A static bed penetration test was first used to study the foam behavior in wetting these powders without the processing constraints of an extruder which limit possible liquid-to-solids ratios as well as introduce shear which may complicate interpretation of the mechanism. The test found that the penetration time to saturate these powders decreased as their water absorption capacity increased which in turn decreased the size of the formed nuclei. Differences in the stability of the foamed binder had minimal influence on these attributes of wetting despite its high spread-to-soak behavior. The size of granules produced by extrusion similarly demonstrated sensitivity to the increasing water absorption capacity of the filler and little dependency on foam properties. The different liquid-to-solids ratios required to granulate these different formulations inside the extruder highlighted an evolving concept of powder lubricity for continuous foam granulation.

  11. Foaming in stout beers

    NASA Astrophysics Data System (ADS)

    Lee, W. T.; Devereux, M. G.

    2011-10-01

    We review the differences between bubble formation in champagne and other carbonated drinks, and stout beers which contain a mixture of dissolved nitrogen and carbon dioxide. The presence of dissolved nitrogen in stout beers gives them several properties of interest to connoisseurs and physicists. These remarkable properties come at a price: stout beers do not foam spontaneously and special technology, such as the widgets used in cans, is needed to promote foaming. Nevertheless, the same mechanism, nucleation by gas pockets trapped in cellulose fibers, responsible for foaming in carbonated drinks is active in stout beers, but at an impractically slow rate. This gentle rate of bubble nucleation makes stout beers an excellent model system for investigating the nucleation of gas bubbles. The equipment needed is modest, putting such experiments within reach of undergraduate laboratories. We also consider the suggestion that a widget could be constructed by coating the inside of a beer can with cellulose fibers.

  12. Microcellular foams; For what

    SciTech Connect

    Aubert, J.H.; Sylwester, A.P. )

    1991-04-01

    This paper discusses the cells of microcellular foams which are thousands of times smaller than those found in conventional foams. They can be used for a whole range of applications, from porous electrodes and high-temperature insulation to electrically conductive composites, and as porous media for studying comet dust. First, the authors will show you how to make them so you can envision their unique characteristics. Then they will show some uses already developed. By far the most versatile preparation technique involves thermally induced phase separation (TIPS) of polymer solutions. In this technique a polymer solution is quenched in order to induce phase separation, either through liquid-liquid phase separation or polymer crystallization. If the TIPS process results in the formation of a continuous polymer-rich phase, two additional processing steps can lead to a microcellular foam.

  13. Low density microcellular foams

    DOEpatents

    LeMay, James D.

    1991-01-01

    Disclosed is a process of producing microcellular foam which comprises the steps of: (a) selecting a multifunctional epoxy oligomer resin; (b) mixing said epoxy resin with a non-reactive diluent to form a resin-diluent mixture; (c) forming a diluent containing cross-linked epoxy gel from said resin-diluent mixture; (d) replacing said diluent with a solvent therefore; (e) replacing said solvent with liquid carbon dioxide; and (f) vaporizing off said liquid carbon dioxide under supercritical conditions, whereby a foam having a density in the range of 35-150 mg/cc and cell diameters less than about 1 .mu.m is produced. Also disclosed are the foams produced by the process.

  14. Low density microcellular foams

    DOEpatents

    LeMay, J.D.

    1991-11-19

    Disclosed is a process of producing microcellular foam which comprises the steps of: (a) selecting a multifunctional epoxy oligomer resin; (b) mixing said epoxy resin with a non-reactive diluent to form a resin-diluent mixture; (c) forming a diluent containing cross-linked epoxy gel from said resin-diluent mixture; (d) replacing said diluent with a solvent therefore; (e) replacing said solvent with liquid carbon dioxide; and (f) vaporizing off said liquid carbon dioxide under supercritical conditions, whereby a foam having a density in the range of 35-150 mg/cc and cell diameters less than about 1 [mu]m is produced. Also disclosed are the foams produced by the process. 8 figures.

  15. Fiber-reinforced syntactic foams

    NASA Astrophysics Data System (ADS)

    Huang, Yi-Jen

    Long fibers are generally preferred for reinforcing foams for performance reasons. However, uniform dispersion is difficult to achieve because they must be mixed with liquid resin prior to foam expansion. New approaches aiming to overcome such problem have been developed at USC's Composites Center. Fiber-reinforced syntactic foams with long fibers (over 6 mm in length) manufactured at USC's Composites Center have achieved promising mechanical properties and demonstrated lower density relative to conventional composite foams. Fiber-reinforced syntactic foams were synthesized from thermosetting polymeric microspheres (amino and phenolic microspheres), as well as thermoplastic PVC heat expandable microspheres (HEMs). Carbon and/or aramid fibers were used to reinforce the syntactic foams. Basic mechanical properties, including shear, tensile, and compression, were measured in syntactic foams and fiber-reinforced syntactic foams. Microstructure and crack propagation behavior were investigated by scanning electron microscope and light microscopy. Failure mechanisms and reinforcing mechanisms of fiber-reinforced syntactic foams were also analyzed. As expected, additions of fiber reinforcements to foams enhanced both tensile and shear properties. However, only limited enhancement in compression properties was observed, and fiber reinforcement was of limited benefit in this regard. Therefore, a hybrid foam design was explored and evaluated in an attempt to enhance compression properties. HEMs were blended with glass microspheres to produce hybrid foams, and hybrid foams were subsequently reinforced with continuous aramid fibers to produce fiber-reinforced hybrid foams. Mechanical properties of these foams were evaluated. Findings indicated that the production of hybrid foams was an effective way to enhance the compressive properties of syntactic foams, while the addition of fiber reinforcements enhanced the shear and tensile performance of syntactic foams. Another approach

  16. Limits on spacetime foam

    SciTech Connect

    Christiansen, Wayne A.; Ng, Y. Jack; Floyd, David J. E.; Perlman, Eric S.

    2011-04-15

    Plausibly spacetime is foamy on small distance scales, due to quantum fluctuations. We elaborate on the proposal to detect spacetime foam by looking for seeing disks in the images of distant quasars and active galactic nuclei. This is a null test in the sense that the continued presence of unresolved point sources at the milliarcsecond level in samples of distant compact sources puts severe constraints on theories of quantized spacetime foam at the Planckian level. We discuss the geometry of foamy spacetime, and the appropriate distance measure for calculating the expected angular broadening. We then deal with recent data and the constraints they put on spacetime foam models. While time lags from distant pulsed sources such as gamma ray bursts have been posited as a possible test of spacetime foam models, we demonstrate that the time-lag effect is rather smaller than has been calculated, due to the equal probability of positive and negative fluctuations in the speed of light inherent in such models. Thus far, images of high-redshift quasars from the Hubble ultra-deep field provide the most stringent test of spacetime foam theories. While random-walk models ({alpha}=1/2) have already been ruled out, the holographic ({alpha}=2/3) model remains viable. Here {alpha}{approx}1 parametrizes the different spacetime foam models according to which the fluctuation of a distance l is given by {approx}l{sup 1-{alpha}l}{sub P}{sup {alpha}} with l{sub P} being the Planck length. Indeed, we see a slight wavelength-dependent blurring in the ultra-deep field images selected for this study. Using existing data in the Hubble Space Telescope (HST) archive we find it is impossible to rule out the {alpha}=2/3 model, but exclude all models with {alpha}<0.65. By comparison, current gamma ray burst time-lag observations only exclude models with {alpha}<0.3.

  17. Permeability optimization and performance evaluation of hot aerosol filters made using foam incorporated alumina suspension.

    PubMed

    Innocentini, Murilo D M; Rodrigues, Vanessa P; Romano, Roberto C O; Pileggi, Rafael G; Silva, Gracinda M C; Coury, José R

    2009-02-15

    Porous ceramic samples were prepared from aqueous foam incorporated alumina suspension for application as hot aerosol filtering membrane. The procedure for establishment of membrane features required to maintain a desired flow condition was theoretically described and experimental work was designed to prepare ceramic membranes to meet the predicted criteria. Two best membranes, thus prepared, were selected for permeability tests up to 700 degrees C and their total and fractional collection efficiencies were experimentally evaluated. Reasonably good performance was achieved at room temperature, while at 700 degrees C, increased permeability was obtained with significant reduction in collection efficiency, which was explained by a combination of thermal expansion of the structure and changes in the gas properties.

  18. Viscosity effects in foam drainage: Newtonian and non-newtonian foaming fluids.

    PubMed

    Safouane, M; Saint-Jalmes, A; Bergeron, V; Langevin, D

    2006-02-01

    We have studied the drainage of foams made from Newtonian and non-Newtonian solutions of different viscosities. Forced-drainage experiments first show that the behavior of Newtonian solutions and of shear-thinning ones (foaming solutions containing either Carbopol or Xanthan) are identical, provided one considers the actual viscosity corresponding to the shear rate found inside the foam. Second, for these fluids, a drainage regime transition occurs as the bulk viscosity is increased, illustrating a coupling between surface and bulk flow in the channels between bubbles. The properties of this transition appear different from the ones observed in previous works in which the interfacial viscoelasticity was varied. Finally, we show that foams made of solutions containing long flexible PolyEthylene Oxide (PEO) molecules counter-intuitively drain faster than foams made with Newtonian solutions of the same viscosity. Complementary experiments made with fluids having all the same viscosity but different responses to elongational stresses (PEO-based Boger fluids) suggest an important role of the elastic properties of the PEO solutions on the faster drainage.

  19. Long lasting decontamination foam

    DOEpatents

    Demmer, Ricky L.; Peterman, Dean R.; Tripp, Julia L.; Cooper, David C.; Wright, Karen E.

    2010-12-07

    Compositions and methods for decontaminating surfaces are disclosed. More specifically, compositions and methods for decontamination using a composition capable of generating a long lasting foam are disclosed. Compositions may include a surfactant and gelatin and have a pH of less than about 6. Such compositions may further include affinity-shifting chemicals. Methods may include decontaminating a contaminated surface with a composition or a foam that may include a surfactant and gelatin and have a pH of less than about 6.

  20. Composite foam structures

    NASA Technical Reports Server (NTRS)

    Williams, Brian E. (Inventor); Brockmeyer, Jerry (Inventor); Tuffias, Robert H. (Inventor)

    2005-01-01

    A composite rigid foam structure that has a skin or coating on at least one of its surfaces. The skin is formed in situ by thermal spray techniques. The skin is bonded substantially throughout the surface of the porous substrate to the peripheries of the pores. The skin on the average does not penetrate the surface of the substrate by more than the depth of about 2 to 5 pores. Thus, thermal spraying the skin onto the rigid foam produces a composite that is tightly and uniformly bonded together without unduly increasing the weight of the composite structure. Both thermal conductivity and bonding are excellent.

  1. Investigation of interfacial rheology & foam stability.

    SciTech Connect

    Yaklin, Melissa A.; Cote, Raymond O.; Grillet, Anne Mary; Walker, Lynn M.; Koehler, Timothy P.; Reichert, Matthew D.; Castaneda, Jaime N.; Mondy, Lisa Ann; Brooks, Carlton, F.

    2010-05-01

    The rheology at gas-liquid interfaces strongly influences the stability and dynamics of foams and emulsions. Several experimental techniques are employed to characterize the rheology at liquid-gas interfaces with an emphasis on the non-Newtonian behavior of surfactant-laden interfaces. The focus is to relate the interfacial rheology to the foamability and foam stability of various aqueous systems. An interfacial stress rheometer (ISR) is used to measure the steady and dynamic rheology by applying an external magnetic field to actuate a magnetic needle suspended at the interface. Results are compared with those from a double wall ring attachment to a rotational rheometer (TA Instruments AR-G2). Micro-interfacial rheology (MIR) is also performed using optical tweezers to manipulate suspended microparticle probes at the interface to investigate the steady and dynamic rheology. Additionally, a surface dilatational rheometer (SDR) is used to periodically oscillate the volume of a pendant drop or buoyant bubble. Applying the Young-Laplace equation to the drop shape, a time-dependent surface tension can be calculated and used to determine the effective dilatational viscosity of an interface. Using the ISR, double wall ring, SDR, and MIR, a wide range of sensitivity in surface forces (fN to nN) can be explored as each experimental method has different sensitivities. Measurements will be compared to foam stability.

  2. Steam foam studies in the presence of residual oil

    SciTech Connect

    Hutchinson, D.A.; Demiral, B.; Castanier, L.M.

    1992-05-01

    The lack of understanding regarding foam flow in porous media necessitates further research. This paper reports on going work at Stanford University aimed at increasing our understanding in the particular area of steam foams. The behavior of steam foam is investigated with a one dimensional (6 ft. {times} 2.15 in.) sandpack under residual oil conditions of approximately 12 percent. The strength of the in-situ generated foam, indicated by pressure drops, is significantly affected by injection procedure, slug size, and steam quality. The surfactant concentration effect is minor in the range studied. In the presence of residual oil the simultaneous injection of steam and surfactant fails to generate foam in the model even though the same procedure generates a strong foam in the absence of oil. Nevertheless when surfactant is injected as a slug ahead of the steam using a surfactant alternating (SAG) procedure, foam is generated. The suggested reason for the success of SAG is the increased phase mixing that results from steam continually having to reestablish a path through a slug of surfactant solution.

  3. Steam foam studies in the presence of residual oil

    SciTech Connect

    Hutchinson, D.A.; Demiral, B.; Castanier, L.M.

    1992-05-01

    The lack of understanding regarding foam flow in porous media necessitates further research. This paper reports on going work at Stanford University aimed at increasing our understanding in the particular area of steam foams. The behavior of steam foam is investigated with a one dimensional (6 ft. {times} 2.15 in.) sandpack under residual oil conditions of approximately 12 percent. The strength of the in-situ generated foam, indicated by pressure drops, is significantly affected by injection procedure, slug size, and steam quality. The surfactant concentration effect is minor in the range studied. In the presence of residual oil the simultaneous injection of steam and surfactant fails to generate foam in the model even though the same procedure generates a strong foam in the absence of oil. Nevertheless when surfactant is injected as a slug ahead of the steam using a surfactant alternating (SAG) procedure, foam is generated. The suggested reason for the success of SAG is the increased phase mixing that results from steam continually having to reestablish a path through a slug of surfactant solution.

  4. Treatment of Basilar Aneurysms with SMP Foams

    NASA Astrophysics Data System (ADS)

    Ortega, J. M.; Rodriguez, J. N.; Maitland, D. J.; Wilson, T. S.; Hartman, J.

    2006-11-01

    Researchers in the Medical Division at LLNL are currently developing a shape memory polymer (SMP) foam aneurysm treatment technique. This technique involves the catheter delivery of a compressed piece of SMP foam to an aneurysm. When the foam is heated by laser radiation from a diffusing fiber-optic element embedded within the catheter, the foam expands, filling the aneurysm volume. If proven successful, such a treatment alternative will provide clinicians the ability to not only isolate an aneurysm from the vascular system with one device, but also to customize the shape of the lumen beneath the aneurysm neck. Consequently, the flow patterns beneath the aneurysm neck could potentially be optimized to minimize the hemodynamic stresses on the lumen. In this computational study, multiple lumen shapes are simulated beneath the necks of several patient-specific basilar aneurysms. A comparison is made between the pre-treatment and post-treatment configurations, as well as with a conventional surgical clipping configuration. This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under Contract No. W-7405-Eng-48. UCRL-ABS-222933.

  5. Foam flotation as a separation process

    NASA Technical Reports Server (NTRS)

    Currin, B. L.

    1986-01-01

    The basic principles of foam separation techniques are discussed. A review of the research concerning bubble-particle interaction and its role in the kinetics of the flotation process is given. Most of the research in this area deals with the use of theoretical models to predict the effects of bubble and particle sizes, of liquid flow, and of various forces on the aperture and retention of particles by bubbles. A discussion of fluid mechanical aspects of particle flotation is given.

  6. Science and Engineering of Carbon Foams

    DTIC Science & Technology

    2006-07-17

    34High Thermal Conductivity, Mesophase Pitch -Derived Carbon Foam", Eurocarbon 98: Science and Technology of Carbon, Strasbourg: French Carbon Group, (1998...production process tends to vary, many processes start with a compacted, porous pre-form of pitch material. The pitch pre-form is then melted under high...pressure of an inert gas. When the pitch material begins to flow above its softening temperature (typically 2500C), the pressure is released to expand

  7. pH stability and comparative evaluation of ranaspumin-2 foam for application in biochemical reactors

    NASA Astrophysics Data System (ADS)

    Choi, Hyo-Jick; Ebersbacher, Charles F.; Quan, Fu-Shi; Montemagno, Carlo D.

    2013-02-01

    Aqueous channels of foam represent a simplified, natural bioreactor on the micro-/nano-scale. Previous studies have demonstrated the feasibility and potential application of foams in replicating cellular process in vitro, but no research has been performed to establish a basis for designing stable and biocompatible foam formulations. Our research has been directed specifically to the evaluation of ranaspumin-2 (RSN-2), a frog foam nest protein. The strong surfactant activity of RSN-2 enabled us to produce foams using low protein concentration (1 mg ml-1) over a wide pH range (pH ≥ 3). Importantly, the RSN-2 formulation exhibited the best foam stability at a near neutral pH condition, which shows a potential for application to various biosynthesis applications. Model cellular systems such as liposomes and inactivated A/PR/8/34 influenza virus maintained their physicochemical stability and full hemagglutination activity, indicating biocompatibility of RSN-2 with both cellular membranes and proteins both in bulk solution and in foam. Moreover, the addition of RSN-2 did not exert any deteriorative effects on bacterial cell growth kinetics. In contrast, Tween 20, Triton X-100, and BSA did not show satisfactory performance in terms of foamability, foam stability, physicochemcial stability, and biochemical stability. Although our study has been limited to representative formulations composed of only surfactant molecules, a number of unique advantages make RSN-2 a promising candidate for in vitro foam biosynthesis.

  8. Tapered plug foam spray apparatus

    NASA Technical Reports Server (NTRS)

    Allen, Peter B. (Inventor)

    1996-01-01

    A two-component foam spray gun is readily disassembled for cleaning. It includes a body (1) with reactant (12, 14) and purge gas (16) inlet ports. A moldable valve packing (32) inside the body has a tapered conical interior surface (142), and apertures which match the reactant ports. A valve/tip (40) has a conical outer surface (48) which mates with the valve packing (32). The valve/tip (40) is held in place by a moldable packing washer (34), held at non-constant pressure by a screw (36, 38). The interior of the valve/tip (40) houses a removable mixing chamber (50). The mixing chamber (50) has direct flow orifices (60) and an auxiliary flow path (58, 60) which ameliorate pressure surges. The spray gun can be disassembled for cleaning without disturbing the seal, by removing the valve/tip (40) to the rear, thereby breaking it free of the conical packing. Rotation of the valve/tip (40) relative to the body (1) shuts off the reactant flow, and starts the purge gas flow.

  9. A comparative study on the solubility and stability of p-phenylenediamine-based organic redox couples for non-aqueous flow batteries

    NASA Astrophysics Data System (ADS)

    Kim, Hyun-seung; Lee, Keon-Joon; Han, Young-Kyu; Ryu, Ji Heon; Oh, Seung M.

    2017-04-01

    A methyl-substituted p-phenylenediamine (PD), N,N,N‧,N‧-tetramethyl-p-phenylenediamine (TMPD), is examined as a positive redox couple with high energy density for non-aqueous Li-flow batteries. Methyl substitution affects the solubility of the redox couple, as the solubility is increased by a factor of ten, to a maximum solubility of 5.0 M in 1.0 M lithium tetrafluoroborate-propylene carbonate supporting electrolyte due to elimination of the hydrogen bonding between the solute molecules. The methyl substitution also enhances the chemical stability of the cation radical and di-cation being generated from PD, as the redox center is shielded by the methyl groups. Furthermore, this organic redox couple demonstrate two-electron redox reactions at 3.2 and 3.8 V (vs. Li/Li+); therefore, the volumetric capacity is twice higher compared to conventional one-electron involved redox couples. In a non-flowing Li/TMPD coin-cell, this organic redox couple demonstrates very stable cycleability as a positive redox couple for non-aqueous flow batteries.

  10. An Approach Toward Replacing Vanadium: A Single Organic Molecule for the Anode and Cathode of an Aqueous Redox‐Flow Battery

    PubMed Central

    Janoschka, Tobias; Friebe, Christian; Hager, Martin D.; Martin, Norbert

    2017-01-01

    Abstract By combining a viologen unit and a 2,2,6,6‐tetramethylpiperidin‐1‐oxyl (TEMPO) radical in one single combi‐molecule, an artificial bipolar redox‐active material, 1‐(4‐(((1‐oxyl‐2,2,6,6‐tetramethylpiperidin‐4‐yl)oxy)carbonyl)benzyl)‐1′‐methyl‐[4,4′‐bipyridine]‐1,1′‐diium‐chloride (VIOTEMP), was created that can serve as both the anode (−0.49 V) and cathode (0.67 V vs. Ag/AgCl) in a water‐based redox‐flow battery. While it mimics the redox states of flow battery metals like vanadium, the novel aqueous electrolyte does not require strongly acidic media and is best operated at pH 4. The electrochemical properties of VIOTEMP were investigated by using cyclic voltammetry, rotating disc electrode experiments, and spectroelectrochemical methods. A redox‐flow battery was built and the suitability of the material for both electrodes was demonstrated through a polarity‐inversion experiment. Thus, an organic aqueous electrolyte system being safe in case of cross contamination is presented. PMID:28413754

  11. An Approach Toward Replacing Vanadium: A Single Organic Molecule for the Anode and Cathode of an Aqueous Redox-Flow Battery.

    PubMed

    Janoschka, Tobias; Friebe, Christian; Hager, Martin D; Martin, Norbert; Schubert, Ulrich S

    2017-04-01

    By combining a viologen unit and a 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO) radical in one single combi-molecule, an artificial bipolar redox-active material, 1-(4-(((1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)oxy)carbonyl)benzyl)-1'-methyl-[4,4'-bipyridine]-1,1'-diium-chloride (VIOTEMP), was created that can serve as both the anode (-0.49 V) and cathode (0.67 V vs. Ag/AgCl) in a water-based redox-flow battery. While it mimics the redox states of flow battery metals like vanadium, the novel aqueous electrolyte does not require strongly acidic media and is best operated at pH 4. The electrochemical properties of VIOTEMP were investigated by using cyclic voltammetry, rotating disc electrode experiments, and spectroelectrochemical methods. A redox-flow battery was built and the suitability of the material for both electrodes was demonstrated through a polarity-inversion experiment. Thus, an organic aqueous electrolyte system being safe in case of cross contamination is presented.

  12. Architected cellular ceramics with tailored stiffness via direct foam writing.

    PubMed

    Muth, Joseph T; Dixon, Patrick G; Woish, Logan; Gibson, Lorna J; Lewis, Jennifer A

    2017-02-21

    Hierarchical cellular structures are ubiquitous in nature because of their low-density, high-specific properties, and multifunctionality. Inspired by these systems, we created lightweight ceramic architectures composed of closed-cell porous struts patterned in the form of hexagonal and triangular honeycombs by direct foam writing. The foam ink contains bubbles stabilized by attractive colloidal particles suspended in an aqueous solution. The printed and sintered ceramic foam honeycombs possess low relative density (∼6%). By tailoring their microstructure and geometry, we created honeycombs with different modes of deformation, exceptional specific stiffness, and stiffness values that span over an order of magnitude. This capability represents an important step toward the scalable fabrication of hierarchical porous materials for applications, including lightweight structures, thermal insulation, tissue scaffolds, catalyst supports, and electrodes.

  13. Attenuation of strong external blast by foam barriers

    NASA Astrophysics Data System (ADS)

    Sembian, S.; Liverts, M.; Apazidis, N.

    2016-09-01

    The mitigation of externally generated strong blast waves by an aqueous foam barrier of varying configurations within fixed distance between the explosion origin and the object to be protected is investigated and quantified both experimentally and numerically. The blast waves of shock Mach number 4.8 at 190 mm from the explosion plane are generated using exploding wire technique. The initially cylindrical blast waves are transformed into a plane blast wave in a specially constructed test unit in which the experiments are performed. The shock waves emanating from the foam barrier are captured using shadowgraph technique. A simple numerical model treating the foam by a pseudo-gas approach is used in interpreting and re-constructing the experimental results. The additional contribution of the impedance mismatch factor is analysed with the aid of numerical simulation and exploited for achieving greater blast wave pressure reduction.

  14. Architected cellular ceramics with tailored stiffness via direct foam writing

    PubMed Central

    Muth, Joseph T.; Dixon, Patrick G.; Woish, Logan; Gibson, Lorna J.; Lewis, Jennifer A.

    2017-01-01

    Hierarchical cellular structures are ubiquitous in nature because of their low-density, high-specific properties, and multifunctionality. Inspired by these systems, we created lightweight ceramic architectures composed of closed-cell porous struts patterned in the form of hexagonal and triangular honeycombs by direct foam writing. The foam ink contains bubbles stabilized by attractive colloidal particles suspended in an aqueous solution. The printed and sintered ceramic foam honeycombs possess low relative density (∼6%). By tailoring their microstructure and geometry, we created honeycombs with different modes of deformation, exceptional specific stiffness, and stiffness values that span over an order of magnitude. This capability represents an important step toward the scalable fabrication of hierarchical porous materials for applications, including lightweight structures, thermal insulation, tissue scaffolds, catalyst supports, and electrodes. PMID:28179570

  15. Architected cellular ceramics with tailored stiffness via direct foam writing

    NASA Astrophysics Data System (ADS)

    Muth, Joseph T.; Dixon, Patrick G.; Woish, Logan; Gibson, Lorna J.; Lewis, Jennifer A.

    2017-02-01

    Hierarchical cellular structures are ubiquitous in nature because of their low-density, high-specific properties, and multifunctionality. Inspired by these systems, we created lightweight ceramic architectures composed of closed-cell porous struts patterned in the form of hexagonal and triangular honeycombs by direct foam writing. The foam ink contains bubbles stabilized by attractive colloidal particles suspended in an aqueous solution. The printed and sintered ceramic foam honeycombs possess low relative density (˜6%). By tailoring their microstructure and geometry, we created honeycombs with different modes of deformation, exceptional specific stiffness, and stiffness values that span over an order of magnitude. This capability represents an important step toward the scalable fabrication of hierarchical porous materials for applications, including lightweight structures, thermal insulation, tissue scaffolds, catalyst supports, and electrodes.

  16. Fire retardant cellulosic foam

    NASA Technical Reports Server (NTRS)

    Luttinger, M.

    1973-01-01

    Method mixture of cyanamide, phosphoric acid, and monobasic ammonium phosphates for preliminary treatment of paper. Papier-mache, in second step, is pulped in water and latex is added. Urea formaldehyde solution mixed to maximize foaming and resin dispersion is added. Mixture is then cast within 30 to 60 seconds and dried twice.

  17. Polyurethane Foam Roofing.

    DTIC Science & Technology

    1987-04-01

    use of asphaltic . bitumen , or coal tar based mastics and plastic type patching materials should be avoided. For purposes of this Guide, maintenance...Applicator Skills......................49 *Spray Foam Equipment and Material Problems. ........ 49 Excess Isocyanate or "A" Component. ............ 50 Excess...surface .. ......... ... 46 35. Isocyanate rich surface .... .............. . 50 36 Resin rich surface ...... ................. ... 51 37 UV

  18. Foam, a promising vehicle to deliver nanoparticles for vadose zone remediation

    NASA Astrophysics Data System (ADS)

    Li, X.; Shen, X.; Zhong, L.; Zhao, L.; Ding, Y.

    2010-12-01

    In-situ immobilization that involves delivering remedial amendments to contaminated locales is an attractive remediation strategy for deep vadose zone contamination. Foam delivery of remedial amendments can overcome the intrinsic problems associated with solution-based delivery, such as preferential flow and contaminant mobilization. In this work, the feasibility of using foam to deliver nanoparticles in unsaturated porous media was investigated. Carboxyl-modified polystyrene latex microspheres were used as surrogates for nanoparticles of remediation purposes. The microsphere concentrations in the foams generated from the solutions of six commonly available surfactants were nearly the same as in the original foaming solutions, indicating the foams had excellent abilities to carry the microspheres. The presence of the microspheres did not reduce the stabilities of the foams. When microsphere-laden foam was injected through the unsaturated columns, the fractions of microsphere exiting the column were much higher than that when the microsphere water suspensions were injected through the columns. The enhanced microsphere transport implies that foam delivery could significantly increase the radius of influence of injected nanoparticles of remediation purposes. Reduced tension at air-water interfaces by the surfactant and increased driving forces imparted on the microspheres at the interfaces by the flowing foam bubbles may have both contributed to the enhanced transport. Preliminary tests also demonstrated that foam can carry significant fractions of zero valent iron nanoparticles (foam concentrations >70% of the concentrations in the stock foaming suspensions) at stock suspension concentrations relevant to field remediation conditions. As such, this study demonstrates that surfactant foam is potentially a promising vehicle to deliver nanoparticles for vadose zone remediation.

  19. Long-range structural order, moiré patterns, and iridescence in latex-stabilized foams.

    PubMed

    Fujii, Syuji; Ryan, Anthony J; Armes, Steven P

    2006-06-21

    We describe the facile production of highly stable foams stabilized solely by micrometer-sized, sterically stabilized polystyrene (PS) latex particles. Such foams can survive for more than one year in the wet state and remain intact after drying. In contrast, foams stabilized with either sodium dodecyl sulfate or poly(N-vinylpyrrolidone) were destroyed after removal of the aqueous phase. Scanning electron microscopy studies reveal hexagonally close-packed arrays of PS particles within the dried foam, which suggests high colloid stability for the PS particles prior to their adsorption at the air-water interface. Localized moiré patterns are observed by optical microscopy due to the formation of well-defined latex bilayers with exquisite long-range order. Moreover, the dried foams are highly iridescent in bright transmitted light, which may offer potential applications in security inks and coatings.

  20. Foam, Foam-resin composite and method of making a foam-resin composite

    NASA Technical Reports Server (NTRS)

    Cranston, John A. (Inventor); MacArthur, Doug E. (Inventor)

    1995-01-01

    This invention relates to a foam, a foam-resin composite and a method of making foam-resin composites. The foam set forth in this invention comprises a urethane modified polyisocyanurate derived from an aromatic amino polyol and a polyether polyol. In addition to the polyisocyanurate foam, the composite of this invention further contains a resin layer, wherein the resin may be epoxy, bismaleimide, or phenolic resin. Such resins generally require cure or post-cure temperatures of at least 350.degree. F.

  1. On the interaction between blast wave and reticulated foams

    NASA Astrophysics Data System (ADS)

    Wilgeroth, James; Proud, William; Ngoc Nguyen, Thuy-Tien; Institute of Shock Physics Team; CentreBlast Injury Studies Team

    2013-06-01

    Injuries to the tympanic membrane (ear drum) and inner ear are particularly common in individuals subjected to blast overpressure, such as military personnel engaged in conflict. Consequently, there is a demand for improved auditory protection systems, which are capable of both preventing this type of injury while providing maximum situational awareness to the user. In this study, a number of reticulated (open cell) foams have been subjected to dynamic compression using shock tube apparatus. Specific effects of porosity; relative density, which is determined by the ratio of cellular material to solid material from which the foam is made; sample thickness; incident pressure; and shock pulses of varying timescale upon the evolution of peak overpressure behind foam samples have been investigated. In addition, the use of Schlieren imaging techniques has allowed for detailed examination of gaseous flow at the rear surface of shocked foam samples.

  2. Vanadium Flow Battery Electrolyte Synthesis via Chemical Reduction of V2O5 in Aqueous HCl and H2SO4.

    SciTech Connect

    Small, Leo J.; Pratt, Harry; Staiger, Chad; Martin, Rachel Irene; Anderson, Travis Mark; Chalamala, Babu; Soundappan, Thiagarajan; Tiwari, Monika; Subarmanian, Venkat R.

    2017-01-01

    We report a simple method to synthesize V 4+ (VO 2+ ) electrolytes as feedstock for all- vanadium redox flow batteries (RFB). By dissolving V 2 O 5 in aqueous HCl and H 2 SO 4 , subsequently adding glycerol as a reducing agent, we have demonstrated an inexpensive route for electrolyte synthesis to concentrations >2.5 M V 4+ (VO 2+ ). Electrochemical analysis and testing of laboratory scale RFB demonstrate improved thermal stability across a wider temperature range (-10-65 degC) for V 4+ (VO 2+ ) electrolytes in HCl compared to in H 2 SO 4 electrolytes.

  3. Synthesis of hierarchical micro/mesoporous structures via solid-aqueous interface growth: zeolitic imidazolate framework-8 on siliceous mesocellular foams for enhanced pervaporation of water/ethanol mixtures.

    PubMed

    Sue, Yu-Chain; Wu, Jhe-Wei; Chung, Shao-En; Kang, Chao-Hsiang; Tung, Kuo-Lun; Wu, Kevin C-W; Shieh, Fa-Kuen

    2014-04-09

    A new hierarchical micro/mesoporous composite is synthesized via direct growth of microporous zeolitic imidazolate framework-8 (ZIF-8) on siliceous mesocellular foams (MCF). Depending on different synthetic conditions, ZIF-8 with two different particle sizes, i.e., ZIF-8 microparticles and ZIF-8 nanoparticles, were successfully formed on the external surface of amine-functionalized MCF (denoted as microZIF-8@MCF and nanoZIF-8@MCF, respectively). The synthesized hierarchical micro/mesoporous ZIF-8@MCF structures were characterized with several spectroscopic techniques including X-ray diffraction (XRD), solid-state NMR, and FT-IR and electron microscopic techniques (scanning electron microscope, SEM, and transmission electron microscopy, TEM). In addition, the pervaporation measurements of the liquid water/ethanol mixture show that nanoZIF-8@MCF/PVA (poly(vinyl alcohol) mixed-matrix membrane exhibits enhanced performance both on the permeability and separation factor. Compared to conventional routes for chemical etching, this study demonstrates a promising and simple strategy for synthesizing novel hierarchical porous composites exhibiting both advantages of mesoporous materials and microporous materials, which is expected to be useful for gas adsorption, separation, and catalysis.

  4. Sida rhomboidea.Roxb aqueous extract down-regulates in vivo expression of vascular cell adhesion molecules in atherogenic rats and inhibits in vitro macrophage differentiation and foam cell formation.

    PubMed

    Thounaojam, Menaka C; Jadeja, Ravirajsinh N; Salunke, Sunita P; Devkar, Ranjitsinh V; Ramachandran, A V

    2012-10-01

    The present study evaluates efficacy of Sida rhomboidea.Roxb (SR) leaves extract in ameliorating experimental atherosclerosis using in vitro and in vivo experimental models. Atherogenic (ATH) diet fed rats recorded significant increment in the serum total cholesterol (TC), triglycerides (TG), low-density lipoprotein (LDL), very LDL (VLDL), autoantibody against oxidized LDL (Ox-LDL), markers of LDL oxidation and decrement in high-density lipoprotein (HDL) along with increment in aortic TC and TG. The ex vivo LDL oxidation assay revealed an increased susceptibility of LDL isolated from ATH rats to undergo copper mediated oxidation. These set of changes were minimized by simultaneous co-supplementation of SR extract to ATH diet fed rats. Histopathology of aorta and immunolocalization studies recorded pronounced atheromatous plaque formation, vascular calcification, significant elastin derangements and higher expression of macrophage surface marker (F4/80), vascular cell adhesion molecule-1 (VCAM-1) and p-selectin in ATH rats. Whereas, ATH+SR rats depicted minimal evidence of atheromatous plaque formation, calcium deposition, distortion/defragmentation of elastin and accumulation of macrophages along with lowered expression of VCAM-1 and P-selectin compared to ATH rats. Further, monocyte to macrophage differentiation and in vitro foam cell formation were significantly attenuated in presence of SR extract. In conclusion, SR extract has the potency of controlling experimental atherosclerosis and can be used as promising herbal supplement in combating atherosclerosis.

  5. Determination of Mercury in Aqueous and Geologic Materials by Continuous Flow-Cold Vapor-Atomic Fluorescence Spectrometry (CVAFS)

    USGS Publications Warehouse

    Hageman, Philip L.

    2007-01-01

    New methods for the determination of total mercury in geologic materials and dissolved mercury in aqueous samples have been developed that will replace the methods currently (2006) in use. The new methods eliminate the use of sodium dichromate (Na2Cr2O7 ?2H2O) as an oxidizer and preservative and significantly lower the detection limit for geologic and aqueous samples. The new methods also update instrumentation from the traditional use of cold vapor-atomic absorption spectrometry to cold vapor-atomic fluorescence spectrometry. At the same time, the new digestion procedures for geologic materials use the same size test tubes, and the same aluminum heating block and hot plate as required by the current methods. New procedures for collecting and processing of aqueous samples use the same procedures that are currently (2006) in use except that the samples are now preserved with concentrated hydrochloric acid/bromine monochloride instead of sodium dichromate/nitric acid. Both the 'old' and new methods have the same analyst productivity rates. These similarities should permit easy migration to the new methods. Analysis of geologic and aqueous reference standards using the new methods show that these procedures provide mercury recoveries that are as good as or better than the previously used methods.

  6. Size-dependent properties of silica nanoparticles for Pickering stabilization of emulsions and foams

    NASA Astrophysics Data System (ADS)

    Kim, Ijung; Worthen, Andrew J.; Johnston, Keith P.; DiCarlo, David A.; Huh, Chun

    2016-04-01

    Nanoparticles are a promising alternative to surfactants to stabilize emulsions or foams in enhanced oil recovery (EOR) processes due to their effectiveness in very harsh environments found in many of the oilfields around the world. While the size-dependent properties of nanoparticles have been extensively studied in the area of optics or cellular uptake, little is known on the effects of nanoparticle size on emulsion/foam generation, especially for EOR applications. In this study, silica nanoparticles with four different sizes (5, 12, 25, and 80 nm nominal diameter) but with the same surface treatment were employed to test their emulsion or foam generation behavior in high-salinity conditions. The decane-in-brine emulsion generated by sonication or flowing through sandpack showed smaller droplet size and higher apparent viscosity as the nanoparticle size decreased. Similarly, the CO2-in-brine foam generation in sandstone or sandpacks was also significantly affected by the nanoparticle size, exhibiting higher apparent foam viscosity as the nanoparticle size decreased. In case of foam generation in sandstone cores with 5 nm nanoparticles, a noticeable hysteresis occurred when the flow velocity was initially increased and then decreased, implying a strong foam generation initially; and then the trapping of the generated foam in the rock pores, as the flow velocity decreased. On the other hand, weak foams stabilized with larger nanoparticles indicated a rapid coalescence of bubbles which prevented foam generation. Overall, stable emulsions/foams were achievable by the smaller particles as a result of greater diffusivity and/or higher number concentration, thus allowing more nanoparticles with higher surface area to volume ratio to be adsorbed at the fluid/fluid interfaces of the emulsion/foam dispersion.

  7. Anion exchange membrane prepared from simultaneous polymerization and quaternization of 4-vinyl pyridine for non-aqueous vanadium redox flow battery applications

    NASA Astrophysics Data System (ADS)

    Maurya, Sandip; Shin, Sung-Hee; Sung, Ki-Won; Moon, Seung-Hyeon

    2014-06-01

    A simple, single step and environmentally friendly process is developed for the synthesis of anion exchange membrane (AEM) by simultaneous polymerization and quaternization, unlike the conventional membrane synthesis which consists of separate polymerization and quaternization step. The membrane synthesis is carried out by dissolving polyvinyl chloride (PVC) in cyclohexanone along with 4-vinyl pyridine (4VP) and 1,4-dibromobutane (DBB) in the presence of thermal initiator benzoyl peroxide, followed by film casting to get thin and flexible AEMs. The membrane properties such as ion exchange capacity, ionic conductivity and swelling behaviour are tuned by varying the degree of crosslinking. These AEMs exhibit low vanadium permeability, while retaining good dimensional and chemical stability in an electrolyte solution, making them appropriate candidates for non-aqueous vanadium acetylacetonate redox flow battery (VRFB) applications. The optimized membrane displays ion exchange capacity and ionic conductivity of 2.0 mequiv g-1 and 0.105 mS cm-1, respectively, whereas the efficiency of 91.7%, 95.7% and 87.7% for coulombic, voltage and energy parameter in non-aqueous VRFB, respectively. This study reveals that the non-aqueous VRFB performance is greatly influenced by membrane properties; therefore the optimal control over the membrane properties is advantageous for the improved performance.

  8. Aqueous pathways dominate permeation of solutes across Pisum sativum seed coats and mediate solute transport via diffusion and bulk flow of water.

    PubMed

    Niemann, Sylvia; Burghardt, Markus; Popp, Christian; Riederer, Markus

    2013-05-01

    The permeability of seed coats to solutes either of biological or anthropogenic origin plays a major role in germination, seedling growth and seed treatment by pesticides. An experimental set-up was designed for investigating the mechanisms of seed coat permeation, which allows steady-state experiments with isolated seed coats of Pisum sativum. Permeances were measured for a set of organic model compounds with different physicochemical properties and sizes. The results show that narrow aqueous pathways dominate the diffusion of solutes across pea seed coats, as indicated by a correlation of permeances with the molecular sizes of the compounds instead of their lipophilicity. Further indicators for an aqueous pathway are small size selectivity and a small effect of temperature on permeation. The application of an osmotic water potential gradient across isolated seed coats leads to an increase in solute transfer, indicating that the aqueous pathways form a water-filled continuum across the seed coat allowing the bulk flow of water. Thus, the uptake of organic solutes across pea testae has two components: (1) by diffusion and (2) by bulk water inflow, which, however, is relevant only during imbibition. © 2012 Blackwell Publishing Ltd.

  9. Size Determination of Aqueous C60 by Asymmetric Flow Field-Flow Fractionation (AF4) and in-Line Dynamic Light Scattering

    EPA Science Inventory

    To date, studies on the environmental behaviour of aggregated aqueous fullerene nanomaterials have used the entire size distribution of fullerene aggregates and do not distinguish between different aggregate size classes. This is a direct result of the lack of analytical methods ...

  10. Size Determination of Aqueous C60 by Asymmetric Flow Field-Flow Fractionation (AF4) and in-Line Dynamic Light Scattering

    EPA Science Inventory

    To date, studies on the environmental behaviour of aggregated aqueous fullerene nanomaterials have used the entire size distribution of fullerene aggregates and do not distinguish between different aggregate size classes. This is a direct result of the lack of analytical methods ...

  11. Model fit to experimental data for foam-assisted deep vadose zone remediation.

    PubMed

    Roostapour, A; Lee, G; Zhong, L; Kam, S I

    2014-01-15

    This study investigates how a foam model, developed in Roostapour and Kam [1], can be applied to make a fit to a set of existing laboratory flow experiments in an application relevant to deep vadose zone remediation. This study reveals a few important insights regarding foam-assisted deep vadose zone remediation: (i) the mathematical framework established for foam modeling can fit typical flow experiments matching wave velocities, saturation history, and pressure responses; (ii) the set of input parameters may not be unique for the fit, and therefore conducting experiments to measure basic model parameters related to relative permeability, initial and residual saturations, surfactant adsorption and so on should not be overlooked; and (iii) gas compressibility plays an important role for data analysis, thus should be handled carefully in laboratory flow experiments. Foam kinetics, causing foam texture to reach its steady-state value slowly, may impose additional complications.

  12. Pore-level mechanics of foam generation and coalescence in the presence of oil.

    PubMed

    Almajid, Muhammad M; Kovscek, Anthony R

    2016-07-01

    The stability of foam in porous media is extremely important for realizing the advantages of foamed gas on gas mobility reduction. Foam texture (i.e., bubbles per volume of gas) achieved is dictated by foam generation and coalescence processes occurring at the pore-level. For foam injection to be widely applied during gas injection projects, we need to understand these pore-scale events that lead to foam stability/instability so that they are modeled accurately. Foam flow has been studied for decades, but most efforts focused on studying foam generation and coalescence in the absence of oil. Here, the extensive existing literature is reviewed and analyzed to identify open questions. Then, we use etched-silicon micromodels to observe foam generation and coalescence processes at the pore-level. Special emphasis is placed on foam coalescence in the presence of oil. For the first time, lamella pinch-off as described by Myers and Radke [40] is observed in porous media and documented. Additionally, a new mechanism coined "hindered generation" is found. Hindered generation refers to the role oil plays in preventing the successful formation of a lamella following snap-off near a pore throat.

  13. Design of metallic foams as insulation in thermal protection systems

    NASA Astrophysics Data System (ADS)

    Zhu, Huadong

    Metallic foams are novel materials that can be used as thermal insulation in many applications. The low volume fraction of solid, the small cell size and the low conductivity of enclosed gases limit the heat flow in foams. Varying the density, geometry and or material composition from point to point within the foam, one can produce functionally graded foams that may insulate more efficiently. The goal of this research is to investigate the use of functionally graded metal foam in thermal protection systems (TPS) for reusable launch vehicles. First, the effective thermal conductivity of the foam is derived based on a simple cubic unit cell model. Then two problems under steady state of heat transfer have been considered. The first one is the optimization of functionally graded foam insulation for minimum heat transmitted to the structure and the second is minimizing the mass of the functionally graded foam insulation for a given aerodynamic heating. In both cases optimality conditions are derived in closed-form, and numerical methods are used to solve the resulting differential equations to determine the optimal grading of the foam. In order to simplify the analysis the insulation was approximated by finite layers of uniform foams when studying the transient heat transfer case. The maximum structure temperature was minimized by varying the solidity profile for a given total thickness and mass. The principles that govern the design of TPS for transient conditions were identified. To take advantage of the load bearing ability of metallic foams, an integrated sandwich TPS/structure with metallic foam core is proposed. Such an integrated TPS will insulate the vehicle interior from aerodynamic heating as well as carry the primary vehicle loads. Thermal-structural analysis of integrated sandwich TPS panel subjected to transient heat conduction is developed to evaluate their performances. The integrated TPS design is compared with a conventional fibrous Safill TPS design

  14. Dust control at longwalls with water infusion and foam. Technical progress report through November 30, 1982

    SciTech Connect

    Not Available

    1982-01-01

    Foam spray equipment and materials for dust suppression on longwall double drum shearer faces have been procured. This equipment includes metering pumps, foam generators and mounting brackets, foam solutions, flow meters, real time and gravimetric sampling equipment, hoses and valve banks. Initial tests have been conducted in the laboratory with three types of generators and five types of foam solutions. Based on these tests, Senior Conflow's cluster spray and Onyx Chemical Company's millifoam solution have been selected. For pumping foam solution to the shearer, Jon Bean's 2 hp, 120 VAC single-phase ceramic lined piston pump has been selected. For field tests, equipment has been installed underground in Dobbin mine in Upper Freeport seam on Eickhoff EDW 300 double drum shearer. Foamspray tests have been conducted. Real time and gravimetric dust samples have been collected. Real time sampling results indicate a dust level reduction of up to 37 percent with foam spray compared to the base case of water sprays.

  15. An overview of polyurethane foams in higher specification foam mattresses.

    PubMed

    Soppi, Esa; Lehtiö, Juha; Saarinen, Hannu

    2015-02-01

    Soft polyurethane foams exist in thousands of grades and constitute essential components of hospital mattresses. For pressure ulcer prevention, the ability of foams to control the immersion and envelopment of patients is essential. Higher specification foam mattresses (i.e., foam mattresses that relieve pressure via optimum patient immersion and envelopment while enabling patient position changes) are claimed to be more effective for preventing pressure ulcers than standard mattresses. Foam grade evaluations should include resiliency, density, hardness, indentation force/load deflection, progressive hardness, tensile strength, and elongation along with essential criteria for higher specification foam mattresses. Patient-specific requirements may include optimal control of patient immersion and envelopment. Mattress cover characteristics should include breathability, impermeability to fluids, and fire safety and not affect mattress function. Additional determinations such as hardness are assessed according to the guidelines of the American Society for Testing and Materials and the International Organization for Standardization. At this time, no single foam grade provides an optimal combination of the above key requirements, but the literature suggests a combination of at least 2 foams may create an optimal higher specification foam mattress for pressure ulcer prevention. Future research and the development of product specification accuracy standards are needed to help clinicians make evidence-based decisions about mattress use.

  16. Foam, a promising vehicle to deliver nanoparticles for vadose zone remediation.

    PubMed

    Shen, Xin; Zhao, Lin; Ding, Yuanzhao; Liu, Bo; Zeng, Hui; Zhong, Lirong; Li, Xiqing

    2011-02-28

    Foam delivery of remedial amendments for in situ immobilization of deep vadose zone contaminants can overcome the intrinsic problems associated with solution-based delivery, such as preferential flow and contaminant mobilization. In this work, the feasibility of using foam to deliver nanoparticles in unsaturated porous media was investigated. Carboxyl-modified polystyrene latex microspheres were used as surrogates for nanoparticles of remediation purposes. Foams generated from the solutions of six commonly available surfactants all had excellent abilities to carry the microspheres. The presence of the microspheres did not reduce the stabilities of the foams. When microsphere-laden foam was injected through the unsaturated columns, the fractions of microspheres exiting the column were much higher than that when the microsphere water suspensions were injected through the columns. The enhanced microsphere transport implies that foam delivery could significantly increase the radius of influence of injected nanoparticles of remediation purposes. Reduced tension at air-water interfaces by the surfactant and increased driving forces imparted on the microspheres at the interfaces by the flowing foam bubbles may have both contributed to the enhanced transport. Preliminary tests also demonstrated that foam can carry significant fractions of zero valent iron nanoparticles at concentrations relevant to field remediation conditions (up to 5.3 g L(-1)). As such, this study demonstrates that surfactant foam is potentially a promising vehicle to deliver nanoparticles for vadose zone remediation.

  17. Foam, a promising vehicle to deliver nanoparticles for vadose zone remediation

    SciTech Connect

    Shen, Xin; Zhao, Lin; Ding, Yuanzhao; Liu, Bo; Zeng, Hui; Zhong, Lirong; Li, Xiqing

    2011-02-23

    Foam delivery of remedial amendments for in-situ immobilization of deep vadose zone contaminants can overcome the intrinsic problems associated with solution-based delivery, such as preferential flow and contaminant mobilization. In this work, the feasibility of using foam to deliver nanoparticles in unsaturated porous media was investigated. Carboxyl-modified polystyrene latex microspheres were used as surrogates for nanoparticles of remediation purposes. Foams generated from the solutions of six commonly available surfactants all had excellent abilities to carry the microspheres. The presence of the microspheres did not reduce the stabilities of the foams. When microsphere-laden foam was injected through the unsaturated columns, the fractions of microspheres exiting the column were much higher than that when the microsphere water suspensions were injected through the columns. The enhanced microsphere transport implies that foam delivery could significantly increase the radius of influence of injected nanoparticles of remediation purposes. Reduced tension at air-water interfaces by the surfactant and increased driving forces imparted on the microspheres at the interfaces by the flowing foam bubbles may have both contributed to the enhanced transport. Preliminary tests also demonstrated that foam can carry significant fractions of zero valent iron nanoparticles at concentrations relevant to field remediation conditions (up to 5.3 g L-1). As such, this study demonstrates that surfactant foam is potentially a promising vehicle to deliver nanoparticles for vadose zone remediation.

  18. Foam injection molding of thermoplastic elastomers: Blowing agents, foaming process and characterization of structural foams

    NASA Astrophysics Data System (ADS)

    Ries, S.; Spoerrer, A.; Altstaedt, V.

    2014-05-01

    Polymer foams play an important role caused by the steadily increasing demand to light weight design. In case of soft polymers, like thermoplastic elastomers (TPE), the haptic feeling of the surface is affected by the inner foam structure. Foam injection molding of TPEs leads to so called structural foam, consisting of two compact skin layers and a cellular core. The properties of soft structural foams like soft-touch, elastic and plastic behavior are affected by the resulting foam structure, e.g. thickness of the compact skins and the foam core or density. This inner structure can considerably be influenced by different processing parameters and the chosen blowing agent. This paper is focused on the selection and characterization of suitable blowing agents for foam injection molding of a TPE-blend. The aim was a high density reduction and a decent inner structure. Therefore DSC and TGA measurements were performed on different blowing agents to find out which one is appropriate for the used TPE. Moreover a new analyzing method for the description of processing characteristics by temperature dependent expansion measurements was developed. After choosing suitable blowing agents structural foams were molded with different types of blowing agents and combinations and with the breathing mold technology in order to get lower densities. The foam structure was analyzed to show the influence of the different blowing agents and combinations. Finally compression tests were performed to estimate the influence of the used blowing agent and the density reduction on the compression modulus.

  19. Development of nonflammable cellulosic foams

    NASA Technical Reports Server (NTRS)

    Luttinger, M.

    1972-01-01

    The development of a moldable cellulosic foam for use in Skylab instrument storage cushions is considered. Requirements include density of 10 lb cu ft or less, minimal friability with normal handling, and nonflammability in an atmosphere of 70 percent oxygen and 30 percent nitrogen at 6.2 psia. A study of halogenated foam components was made, including more highly chlorinated binders, halogen-containing additives, and halogenation of the cellulose. The immediate objective was to reduce the density of the foam through reduction in inorganic phosphate without sacrificing flame-retarding properties of the foams. The use of frothing techniques was investigated, with particular emphasis on a urea-formaldehyde foam. Halogen-containing flame retardants were deemphasized in favor of inorganic salts and the preparation of phosphate and sulphate esters of cellulose. Utilization of foam products for civilian applications was also considered.

  20. Metal Foam Shields

    NASA Technical Reports Server (NTRS)

    Christiansen, Eric L.

    2006-01-01

    This paper compares the ballistic performance of metallic foam sandwich structures with honeycomb structures. Honeycomb sandwich structures, consisting of metallic or composite facesheets and honeycomb cores, are often used in spacecraft construction due to their light-weight and structural stiffness. Honeycomb panels, however, are considered rather poor candidates for protection from micrometeoroid orbital debris (MMOD) particles because the honeycomb channels the debris cloud from MMOD impacts on outer facesheet causing a concentrated load on the second facesheet. Sandwich structures with light-weight, open-cell metallic cores and metal or composite facesheets provide improved MMOD protection because channeling does not occur and because the core is more effective at disrupting hypervelocity impacts then honeycomb. This paper describes hypervelocity impact tests on metallic foam sandwich structures (aluminum and titanium) with metallic facesheets, compare them to equivalent mass and thickness honeycomb panels, based on the results of hypervelocity impact tests.