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Sample records for liquid fuel droplets

  1. Combustion of liquid fuel droplets in supercritical conditions

    NASA Technical Reports Server (NTRS)

    Shuen, J. S.; Yang, Vigor

    1991-01-01

    A comprehensive analysis of liquid-fuel droplet combustion in both sub- and super-critical environments has been conducted. The formulation is based on the complete conservation equations for both gas and liquid phases, and accommodates finite-rate chemical kinetics and a full treatment of liquid-vapor phase equilibrium at the droplet surface. The governing equations and the associated interface boundary conditions are solved numerically using a fully coupled, implicit scheme with the dual time-stepping integration technique. The model is capable of treating the entire droplet history, including the transition from the subcritical to the supercritical state. As a specific example, the combustion of n-pentane fuel droplets in air is studied for pressures of 5-140 atm. Results indicate that the ambient gas pressure exerts significant control of droplet gasification and burning processes through its influences on the fluid transport, gas/liquid interface thermodynamics, and chemical reactions. The droplet gasification rate increases progressively with pressure. However, the data for the overall burnout time exhibits a significant variation near the critical burning pressure, mainly as a result of reduced mass-diffusion rate and latent heat of vaporization with increased pressure. The influence of droplet size on the burning characteristics is also noted.

  2. Combustion of liquid-fuel droplets in supercritical conditions

    NASA Technical Reports Server (NTRS)

    Shuen, J. S.; Yang, Vigor; Hsaio, C. C.

    1992-01-01

    A comprehensive analysis of liquid-fuel droplet combustion in both subcritical and supercritical environments has been conducted. The formulation is based on the complete conservation equations for both gas and liquid phases, and accommodates variable thermophysical properties, finite-rate chemical kinetics, and a full treatment of liquid-vapor phase equilibrium at the drop surface. The governing equations and associated interfacial boundary conditions are solved numerically using a fully coupled, implicit scheme with the dual time-stepping integration technique. The model is capable of treating the entire droplet history, including the transition from the subcritical to supercritical state. As a specific example, the combustion of n-pentane fuel droplets in air is studied for pressures in the range of 5-140 atm. Results indicate that the ambient gas pressure exerts significant control of droplet gasification and burning processes through its influence on fluid transport, gas-liquid interfacial thermodynamics, and chemical reactions. The droplet gasification rate increases progressively with pressure. However, the data for the overall burnout time exhibit a considerable change in the combustion mechanism at the critical pressure, mainly as a result of reduced mass diffusivity and latent heat of vaporization with increased pressure.

  3. Acoustic excitation of liquid fuel droplets and coaxial jets

    NASA Astrophysics Data System (ADS)

    Rodriguez, Juan Ignacio

    This experimental study focuses on two important problems relevant to acoustic coupling with condensed phase transport processes, with special relevance to liquid rocket engine and airbreathing engine combustion instabilities. The first part of this dissertation describes droplet combustion characteristics of various fuels during exposure to external acoustical perturbations. Methanol, ethanol, a liquid synthetic fuel derived from coal gasification via the Fischer-Tropsch process, and a blend of aviation fuel and the synthetic fuel are used. During acoustic excitation, the droplet is situated at or near a pressure node condition, where the droplet experiences the largest velocity perturbations, and at or near a pressure antinode condition, where the droplet is exposed to minimal velocity fluctuations. For unforced conditions, the values of the droplet burning rate constant K of the different fuels are consistent with data in the literature. The location of the droplet with respect to a pressure node or antinode also has a measurable effect on droplet burning rates, which are different for different fuels and in some cases are as high as 28% above the unforced burning rate value. Estimates of flame extinction due to acoustic forcing for different fuels are also obtained. The second part of this work consists of an experimental study on coaxial jet behavior under non-reactive, cryogenic conditions, with direct applications to flow mixing and unstable behavior characterization in liquid rocket engines. These experiments, conducted with nitrogen, span a range of outer to inner jet momentum flux ratios from 0.013 to 23, and explore subcritical, nearcritical and supercritical pressure conditions, with and without acoustic excitation, for two injector geometries. Acoustic forcing at 3 kHz is utilized to maximize the pressure fluctuations within the chamber acting on the jet, reaching maximum values of 4% of the mean chamber pressure. The effect of the magnitude and phase

  4. Pressure-coupled vaporization and combustion responses of liquid-fuel droplets in high-pressure environments

    NASA Technical Reports Server (NTRS)

    Yang, Vigor; Shuen, J. S.; Hsiao, C. C.

    1991-01-01

    The dynamic responses of liquid-fuel droplet vaporization and combustion to ambient pressure oscillations are examined. The analysis is based on the complete sets of conservation equations for both gas and liquid phases, and accommodates detailed treatments of finite-rate chemical kinetics and variable properties. With a full account of thermodynamic phase equilibrium at the droplet surface, the model enables a systematic examination of the effects of ambient flow conditions on the droplet behavior. The responses of hydrocarbon fuel droplets in both sub- and super-critical environments are investigated. Results indicate that the droplet gasification and burning mechanisms depend greatly on the ambient pressure. In particular, a rapid enlargement of the vaporization and combustion responses occurs when the droplet surface reaches its critical point, mainly due to the strong variations of latent heat of vaporization and thermophysical properties at the critical state.

  5. Liquid droplet generation

    NASA Technical Reports Server (NTRS)

    Muntz, E. P.; Orme, Melissa; Farnham, Tony; Vandiep, G. Pham; Huerre, P.

    1989-01-01

    A pre-prototype segment of a droplet sheet generator for a liquid droplet radiator was designed, constructed and tested. The ability to achieve a uniform, non-diverging droplet sheet is limited by manufacturing tolerances on nozzle parallelism. For an array of 100, 100 micrometer diameters nozzles spaced 5 stream diameters apart, typical standard deviations in stream alignment were plus or minus 10 mrad. The drop to drop fractional speed variations of the drops in typical streams were similar and independent of position in the array. The absolute value of the speed dispersion depended on the amplitude of the disturbance applied to the stream. A second generation preliminary design of a 5200 stream segment of a droplet sheet generator was completed. The design is based on information developed during testing of the pre-prototype segment, along with the results of an acoustical analysis for the stagnation cavity pressure fluctuations used to break-up the streams into droplets.

  6. Fuel Droplet Burning During Droplet Combustion Experiment

    NASA Technical Reports Server (NTRS)

    2003-01-01

    Fuel ignites and burns in the Droplet Combustion Experiment (DCE) on STS-94 on July 4 1997, MET:2/05:40 (approximate). The DCE was designed to investigate the fundamental combustion aspects of single, isolated droplets under different pressures and ambient oxygen concentrations for a range of droplet sizes varying between 2 and 5 mm. DCE used various fuels -- in drops ranging from 1 mm (0.04 inches) to 5 mm (0.2 inches) -- and mixtures of oxidizers and inert gases to learn more about the physics of combustion in the simplest burning configuration, a sphere. The experiment elapsed time is shown at the bottom of the composite image. The DCE principal investigator was Forman Williams, University of California, San Diego. The experiment was part of the space research investigations conducted during the Microgravity Science Laboratory-1R mission (STS-94, July 1-17 1997). Advanced combustion experiments will be a part of investigations plarned for the International Space Station. (1.4MB, 13-second MPEG, screen 320 x 240 pixels; downlinked video, higher quality not available)A still JPG composite of this movie is available at http://mix.msfc.nasa.gov/ABSTRACTS/MSFC-0300168.html.

  7. Levitation of liquid sodium droplets

    SciTech Connect

    Roy, S.S.; Cramb, A.W.; Hoburg, J.F.; Lally, B.

    1995-12-01

    Droplets of liquid sodium ranging from 1.2 to 2.1 g, immersed in mineral oil, were levitated in an electromagnetic field. The experimental setup was designed and constructed to levitate small metal droplets at audio frequencies. The levitated droplet was found to be very stable inside the inductor, and the equilibrium shape attained by the droplet in the electromagnetic field was measured during the experiment. A surface coupled mathematical model was used to calculate the self-consistent equilibrium droplet shape of liquid sodium under the influence of an electromagnetic field. The predicted shapes of the metal droplet and the position of the droplet inside the inductor compare well with the experimental data. The idea of casting metals and alloys without any physical contact has generated a lot of interest in the metals industry, especially in the production of metals/alloys that are highly reactive and have a very high melting point. Containerless casting can be achieved by levitating or pushing the liquid metal from the surface of the container.

  8. Measurement of vapor/liquid distributions in a binary-component fuel spray using laser imaging of droplet scattering and vapor absorption

    NASA Astrophysics Data System (ADS)

    Li, Shiyan; Zhang, Yuyin; Wu, Shenqi; Xu, Bin

    2014-08-01

    Fuel volatility has a great effect on its evaporation processes and the mixture formation and thus combustion and emissions formation processes in internal combustion engines. To date, however, instead of the actual gasoline or diesel fuel, many researchers have been using single-component fuel in their studies, because the composition of the former is too complicated to understand the real physics behind the evaporation and combustion characteristics. Several research groups have reported their results on droplets evaporation in a spray of multi-component fuel, carried out both numerically and experimentally. However, there are plenty of difficulties in quantitative determination of vapor concentration and droplet distributions of each component in a multicomponent fuel spray. In this study, to determine the vapor phase concentration and droplet distributions in an evaporating binary component fuel spray, a laser diagnostics based on laser extinction by droplet scattering and vapor absorption was developed. In practice, measurements of the vapor concentration distributions of the lower (n-tridencane) and higher (n-octane) volatility components in the binary component fuel sprays have been carried out at ambient temperatures of 473K and 573K, by substituting p-xylene for noctane or α-methylnaphthalene for n-tridecane. p-Xylene and α-methylnaphthalene were selected as the substitutes is because they have strong absorption band near 266nm and transparent near 532nm and, their thermo-physical properties are similar to those of the original component. As a demonstration experiment, vapor/liquid distribution of the lower boiling point (LBP) and higher boiling point (HBP) components in the binary component fuel spray have been obtained.

  9. Investigation of critical burning of fuel droplets

    NASA Technical Reports Server (NTRS)

    Allison, C. B.; Canada, G. S.; Faeth, G. M.

    1972-01-01

    Measurements were made on the burning of liquid hydrazine, MMH, and UDMH in a combustion gas environment. The experimental range of these tests involved gas temperatures of 1660-2530 K, oxygen concentrations of 0-42% by mass and droplet diameters (employing both droplets and porous spheres) of 0.11-1.91 cm. at atmospheric pressure. A simplified hybrid combustion theory was developed which was found to correlate the present results as well as the experimental measurements of other investigators. Measurements were also made of the monopropellant strand burning rates and liquid surface temperatures of a number of nitrate ester fuels and hydrazine at elevated pressures. The temperature measurements for the nitrate esters were found to be in good agreement with a theoretical model which allowed for gas solubility in the liquid phase at high pressures. Experimental results were also obtained on the burning rates and liquid surface temperatures of a number of paraffin and alcohol fuels burning in air pressures up to 72 atm. For these tests, the fuels were burned from porous spheres in a natural convection environment. Initial findings on a pressurized flat flame burner are also described as well as the design of an oscillatory combustion apparatus to test the response of burning liquid fuels.

  10. Transient burning of a convective fuel droplet

    SciTech Connect

    Wu, Guang; Sirignano, William A.

    2010-05-15

    The transient burning of an n-octane fuel droplet in a hot gas stream at 20 atmosphere pressure is numerically studied, with considerations of droplet regression, deceleration due to the drag of the droplet, internal circulation inside the droplet, variable properties, non-uniform surface temperature, and the effect of surface tension. An initial envelope flame is found to remain envelope in time, and an initial wake flame is always transitioned into an envelope flame at a later time, with the normalized transition delay controlled by the initial Reynolds number and the initial Damkohler number. The initial flame shape is primarily determined by the initial Damkohler number, which has a critical value of Da{sub 0}=1.02. The burning rates are modified by the transition, and are influenced by the intensity of forced convection which is determined by initial Reynolds number. The influence of surface tension is also studied as the surface temperature is non-uniform. Surface tension affects the liquid motion at the droplet surface significantly and affects the change of surface temperature and burning rate modestly. The influence of surface tension generally increases with increasing initial Reynolds number within the range without droplet breakup. We also studied cases with constant relative velocity between the air stream and the droplet. The results show that in these cases the initial envelope flame still remains envelope, but the evolution from an initial wake flame to an envelope flame is inhibited. Validation of our analysis is made by comparing with a published porous-sphere experiment Raghavan et al. (2005) which used methanol fuel. (author)

  11. Analysis of transport mechanisms in dense fuel droplet sprays

    SciTech Connect

    Kleinstreuer, C.

    1991-05-01

    This report deals with numerical analyses of fluid mechanics, heat transfer, mass transfer and particle dynamics of interacting spheres and vaporizing droplets in a linear array or on a 1-D trajectory. Available finite element software has been modified and extended to solve several case studies including closely spaced monodisperse spheres with or without blowing; closely spaced vaporizing fuel droplets; and dynamically interacting vaporizing fuel droplets on a 1-D trajectory. Axisymmetric laminar flow has been assumed for three statically or dynamically interacting spherical solids and vaporizing droplets. Emphasis in this work is evaluating the effects of key system parameters, such as free stream Reynolds number, interparticle spacings, liquid/gas-phase viscosity ratio and variable fluid properties, on interfacial transfer processes and on the particle Nusselt number, vaporization rate and drag coefficient. Computer-generated correlations between integral quantities and system parameters were postulated for blowing spheres and vaporizing droplets. In addition to initial Reynolds number and droplet spacings, variable fluid properties, liquid-phase heating and internal droplet circulation have strong effect on the dynamic behavior of multi-droplet systems. While the lead droplet is most significantly affected by all key parameters, the second and third droplet causes distinct interaction effects which are largely dependent on initial droplet spacings. Applications include spherical-structure/fluid-flow interactions, as well as interacting vaporizing droplets in different sprays related to propulsion systems, irrigation, spray coating, etc. Focusing on fuel droplet sprays, results of the dynamic multi-droplet study can assist in better atomizers and combustion chamber designs which may lead to improved combustion efficiencies, smaller/lighter systems, and reduced pollutant emissions.

  12. Ceramic liquid droplets stabilized in vacuum

    NASA Astrophysics Data System (ADS)

    Takahashi, R.; Tsuruta, Y.; Yonezawa, Y.; Ohsawa, T.; Koinuma, H.; Matsumoto, Y.

    2007-02-01

    We have studied the ceramic liquid droplet of CuOx-added BiOx at high temperature in vacuum. CuOx always floated on the BiOx as a surfactant and suppressed the evaporation of volatile BiOx liquid droplets. A clear liquid behavior of the BiOx droplets was directly observed by in situ laser microscope, with numerous liquid droplets growing by the coalescences in accordance with Marangoni's [Nuovo Cimento Ser. 2, 239 (1872)] effect involved with the precursor film. We have also found a unique absorption of CaO into the BiOx liquid droplets, based on which a reliable process has been established for an atomically flat surface of MgO(001). These results open a broad window of opportunity to tailor not only a chemical interaction on oxide surface but also a liquid droplet dynamics in vacuum.

  13. Investigation of critical burning of fuel droplets. [monopropellants

    NASA Technical Reports Server (NTRS)

    Faeth, G. M.; Chanin, S.

    1974-01-01

    The steady combustion characteristics of droplets were considered in combustion chamber environments at various pressures, flow conditions, and ambient oxidizer concentrations for a number of hydrocarbon fuels. Using data obtained earlier, predicted gasification rates were within + or - 30% of measurements when the correction for convection was based upon average properties between the liquid surface and the flame around the droplet. Analysis was also completed for the open loop response of monopropellant droplets, based upon earlier strand combustion results. At the limit of large droplets, where the effect of flame curvature is small, the results suggest sufficient response to provide a viable mechanism for combustion instability in the frequency and droplet size range appropriate to practical combustors. Calculations are still in progress for a broader range of droplet sizes, including conditions where active combustion effects are small.

  14. How faceted liquid droplets grow tails.

    PubMed

    Guttman, Shani; Sapir, Zvi; Schultz, Moty; Butenko, Alexander V; Ocko, Benjamin M; Deutsch, Moshe; Sloutskin, Eli

    2016-01-19

    Liquid droplets, widely encountered in everyday life, have no flat facets. Here we show that water-dispersed oil droplets can be reversibly temperature-tuned to icosahedral and other faceted shapes, hitherto unreported for liquid droplets. These shape changes are shown to originate in the interplay between interfacial tension and the elasticity of the droplet's 2-nm-thick interfacial monolayer, which crystallizes at some T = Ts above the oil's melting point, with the droplet's bulk remaining liquid. Strikingly, at still-lower temperatures, this interfacial freezing (IF) effect also causes droplets to deform, split, and grow tails. Our findings provide deep insights into molecular-scale elasticity and allow formation of emulsions of tunable stability for directed self-assembly of complex-shaped particles and other future technologies. PMID:26733673

  15. Liquid droplet heat exchanger studies

    NASA Technical Reports Server (NTRS)

    Bruckner, A. P.; Hedges, D. E.; Yungster, S.

    1987-01-01

    Recent analytical and experimental investigations of the liquid droplet heat exchanger (LDHX) concept for space power applications are described. The performance of the LDHX is compared to that of a conventional heat exchanger for heat rejection applications in a Brayton cycle, using the mass-specific heat exchanger effectiveness as a figure of merit. It is shown that the LDHX has an order of magnitude advantage over the conventional heat exchanger. Furthermore, significant improvement in cycle efficiency and power to mass ratio is possible. Two-phase flow experiments in a laboratory scale LDHX, using air and water as the two media, show very good agreement with the quasi-one-dimensional model used in the parametric studies.

  16. Vaporization and combustion of fuel droplets at supercritical conditions

    NASA Technical Reports Server (NTRS)

    Yang, Vigor

    1991-01-01

    Vaporization and combustion liquid-fuel droplets in both sub- and super-critical environments have been examined. The formulation is based on the complete conservation equations for both gas and liquid phases, and accommodates finite-rate chemical kinetics and a full treatment of liquid-vapor phase equilibrium at the droplet surface. The governing equations and the associated interface boundary conditions are solved numerically using a fully coupled, implicit scheme with the dual time-stepping integration technique. The model is capable of treating the entire droplet history, including the transition from the subcritical to the supercritical state. As a specific example, the combustion of n-pentane fuel droplets in air is studied for pressures of 5-140 atm. In addition, the dynamic responses of droplet vaporization and combustion to ambient-pressure oscillations are investigated. Results indicate that the droplet gasification and burning mechanisms depend greatly on the ambient pressure. In particular, a rapid enlargement of the vaporization and combustion responses occurs when the droplet surface reaches its critical point, mainly due to the strong variations of latent heat of vaporization and thermophysical properties at the critical state.

  17. Oscillatory combustion of liquid monopropellant droplets

    NASA Technical Reports Server (NTRS)

    Chanin, S. P.; Faeth, G. M.

    1976-01-01

    A theoretical investigation was conducted on the open-loop combustion response of monopropellant droplets and sprays to imposed pressure oscillations. The theoretical model was solved as a perturbation analysis through first order, yielding linear response results. Unsteady gas phase effects were considered in some cases, but the bulk of the calculations assumed a quasi-steady gas phase. Calculations were conducted using properties corresponding to hydrazine decomposition. Zero-order results agreed with earlier measurements of hydrazine droplet burning in combustion gases. The droplet response was greatest (exceeding unity in some cases) for large droplets with liquid phase temperature gradients; at frequencies near the characteristic frequency of the liquid phase thermal wave. The response of a spray is less than that of its largest droplet, however, a relatively small percentage of large droplets provides a substantial response (exceeding unity in some cases).

  18. Self-propelled chemotactic ionic liquid droplets.

    PubMed

    Francis, Wayne; Fay, Cormac; Florea, Larisa; Diamond, Dermot

    2015-02-11

    Herein we report the chemotactic behaviour of self-propelled droplets composed solely of the ionic liquid trihexyl(tetradecyl)phosphonium chloride ([P(6,6,6,14)][Cl]). These droplets spontaneously move along an aqueous-air boundary in the direction of chloride gradients to specific destinations due to asymmetric release of [P(6,6,6,14)](+) cationic surfactant from the droplet into the aqueous phase.

  19. Measurements in liquid fuel sprays

    NASA Technical Reports Server (NTRS)

    Chigier, N.

    1984-01-01

    Techniques for studying the events directly preceding combustion in the liquid fuel sprays are being used to provide information as a function of space and time on droplet size, shape, number density, position, angle of flight and velocity. Spray chambers were designed and constructed for: (1) air-assist liquid fuel research sprays; (2) high pressure and temperature chamber for pulsed diesel fuel sprays; and (3) coal-water slurry sprays. Recent results utilizing photography, cinematography, and calibration of the Malvern particle sizer are reported. Systems for simultaneous measurement of velocity and particle size distributions using laser Doppler anemometry interferometry and the application of holography in liquid fuel sprays are being calibrated.

  20. Investigation of critical burning of fuel droplets

    NASA Technical Reports Server (NTRS)

    Faeth, G. M.

    1979-01-01

    The general problem of spray combustion was investigated. The combustion of bipropellent droplets; combustion of hydrozine fuels; and combustion of sprays were studied. A model was developed to predict mean velocities and temperatures in a combusting gas jet.

  1. Kinetics of complex plasma with liquid droplets

    SciTech Connect

    Misra, Shikha; Sodha, M. S.; Mishra, S. K.

    2013-12-15

    This paper provides a theoretical basis for the reduction of electron density by spray of water (or other liquids) in hot plasma. This phenomenon has been observed in a hypersonic flight experiment for relief of radio black out, caused by high ionization in the plasma sheath of a hypersonic vehicle, re-entering the atmosphere. The analysis incorporates a rather little known phenomenon for de-charging of the droplets, viz., evaporation of ions from the surface and includes the charge balance on the droplets and number cum energy balance of electrons, ions, and neutral molecules; the energy balance of the evaporating droplets has also been taken into account. The analysis has been applied to a realistic situation and the transient variations of the charge and radius of water droplets, and other plasma parameters have been obtained and discussed. The analysis through made in the context of water droplets is applicable to all liquids.

  2. Bouncing of polymeric droplets on liquid interfaces.

    PubMed

    Gier, S; Dorbolo, S; Terwagne, D; Vandewalle, N; Wagner, C

    2012-12-01

    The effect of polymers on the bouncing behavior of droplets in a highly viscous, vertically shaken silicone oil bath was investigated in this study. Droplets of a sample liquid were carefully placed on a vibrating bath that was maintained well below the threshold of Faraday waves. The bouncing threshold of the plate acceleration depended on the acceleration frequency. For pure water droplets and droplets of aqueous polymer solutions, a minimum acceleration amplitude was observed in the acceleration threshold curves as a function of frequency. The bouncing acceleration amplitude for a droplet of a dilute aqueous polymer solution was higher than the acceleration amplitude for a pure water droplet. Measurements of the center of mass trajectory and the droplet deformations showed that the controlling parameter in the bouncing process was the oscillating elongational rate of the droplet. This parameter can be directly related to the elongational viscosity of the polymeric samples. The large elongational viscosity of the polymer solution droplets suppressed large droplet deformations, resulting in less chaotic bouncing. PMID:23368045

  3. How faceted liquid droplets grow tails

    PubMed Central

    Guttman, Shani; Sapir, Zvi; Schultz, Moty; Butenko, Alexander V.; Ocko, Benjamin M.; Deutsch, Moshe; Sloutskin, Eli

    2016-01-01

    Liquid droplets, widely encountered in everyday life, have no flat facets. Here we show that water-dispersed oil droplets can be reversibly temperature-tuned to icosahedral and other faceted shapes, hitherto unreported for liquid droplets. These shape changes are shown to originate in the interplay between interfacial tension and the elasticity of the droplet’s 2-nm-thick interfacial monolayer, which crystallizes at some T = Ts above the oil’s melting point, with the droplet’s bulk remaining liquid. Strikingly, at still-lower temperatures, this interfacial freezing (IF) effect also causes droplets to deform, split, and grow tails. Our findings provide deep insights into molecular-scale elasticity and allow formation of emulsions of tunable stability for directed self-assembly of complex-shaped particles and other future technologies. PMID:26733673

  4. Droplet impact on falling liquid films

    NASA Astrophysics Data System (ADS)

    Matar, Omar; Che, Zhizhao; Zadrazil, Ivan; Hewitt, Geoffrey; Markides, Christos

    2013-11-01

    Droplet impact is a ubiquitous phenomenon in nature, and has a wide range of applications; these include inkjet printing, spray painting, and surface cleaning. In this study, we examine the impact of droplets on falling liquid films, which is an event that occurs in various two-phase flows, such as annular flows and spray cooling. High-speed photography is used to visualise droplet impact, and associated phenomena, on a uniform falling liquid film, which is created on a flat substrate with controllable thickness and flow speed. Different phenomena are observed and analysed for droplet impact at different impact speeds, angles, and film thicknesses and flow speeds. The results of the present work are part of a programme to elucidate the complex dynamics of multiphase flows and to develop validated numerical tools for accurate predictions. EPSRC Programme Grant EP/K003976/1.

  5. The investigation of critical burning of fuel droplets

    NASA Technical Reports Server (NTRS)

    Allison, C. B.; Canada, G. S.; Faeth, G. M.

    1973-01-01

    The combustion and evaporation of liquid fuels at high pressures were investigated. Particular emphasis was placed on conditions where the liquid surface approaches the thermodynamic critical point during combustion. The influence of transient effects on a burning liquid fuel was also investigated through both analysis and measurements of the response of liquid monopropellant combustion to imposed pressure oscillations. Work was divided into four phases (1) Droplet combustion at high pressures, which consider both measurement and analysis of the porous sphere burning rate of liquids in a natural convection environment at elevated pressure. (2) High pressure droplet burning in combustion gases, which involved steady burning and evaporation of liquids from porous spheres in a high pressure environment that simulates actual combustion chamber conditions. (3) Liquid strand combustion, which considered the burning rate, the state of the liquid surface and the liquid phase temperature distribution of a burning liquid monopropellant column over a range of pressures. (4) Oscillatory combustion, which was a theoretical and experimental investigation of the response of a burning liquid monopropellant to pressure oscillations.

  6. Vitrification and levitation of a liquid droplet on liquid nitrogen.

    PubMed

    Song, Young S; Adler, Douglas; Xu, Feng; Kayaalp, Emre; Nureddin, Aida; Anchan, Raymond M; Maas, Richard L; Demirci, Utkan

    2010-03-01

    The vitrification of a liquid occurs when ice crystal formation is prevented in the cryogenic environment through ultrarapid cooling. In general, vitrification entails a large temperature difference between the liquid and its surrounding medium. In our droplet vitrification experiments, we observed that such vitrification events are accompanied by a Leidenfrost phenomenon, which impedes the heat transfer to cool the liquid, when the liquid droplet comes into direct contact with liquid nitrogen. This is distinct from the more generally observed Leidenfrost phenomenon that occurs when a liquid droplet is self-vaporized on a hot plate. In the case of rapid cooling, the phase transition from liquid to vitrified solid (i.e., vitrification) and the levitation of droplets on liquid nitrogen (i.e., Leidenfrost phenomenon) take place simultaneously. Here, we investigate these two simultaneous physical events by using a theoretical model containing three dimensionless parameters (i.e., Stefan, Biot, and Fourier numbers). We explain theoretically and observe experimentally a threshold droplet radius during the vitrification of a cryoprotectant droplet in the presence of the Leidenfrost effect. PMID:20176969

  7. Vitrification and levitation of a liquid droplet on liquid nitrogen

    PubMed Central

    Song, Young S.; Adler, Douglas; Xu, Feng; Kayaalp, Emre; Nureddin, Aida; Anchan, Raymond M.; Maas, Richard L.; Demirci, Utkan

    2010-01-01

    The vitrification of a liquid occurs when ice crystal formation is prevented in the cryogenic environment through ultrarapid cooling. In general, vitrification entails a large temperature difference between the liquid and its surrounding medium. In our droplet vitrification experiments, we observed that such vitrification events are accompanied by a Leidenfrost phenomenon, which impedes the heat transfer to cool the liquid, when the liquid droplet comes into direct contact with liquid nitrogen. This is distinct from the more generally observed Leidenfrost phenomenon that occurs when a liquid droplet is self-vaporized on a hot plate. In the case of rapid cooling, the phase transition from liquid to vitrified solid (i.e., vitrification) and the levitation of droplets on liquid nitrogen (i.e., Leidenfrost phenomenon) take place simultaneously. Here, we investigate these two simultaneous physical events by using a theoretical model containing three dimensionless parameters (i.e., Stefan, Biot, and Fourier numbers). We explain theoretically and observe experimentally a threshold droplet radius during the vitrification of a cryoprotectant droplet in the presence of the Leidenfrost effect. PMID:20176969

  8. Vitrification and levitation of a liquid droplet on liquid nitrogen.

    PubMed

    Song, Young S; Adler, Douglas; Xu, Feng; Kayaalp, Emre; Nureddin, Aida; Anchan, Raymond M; Maas, Richard L; Demirci, Utkan

    2010-03-01

    The vitrification of a liquid occurs when ice crystal formation is prevented in the cryogenic environment through ultrarapid cooling. In general, vitrification entails a large temperature difference between the liquid and its surrounding medium. In our droplet vitrification experiments, we observed that such vitrification events are accompanied by a Leidenfrost phenomenon, which impedes the heat transfer to cool the liquid, when the liquid droplet comes into direct contact with liquid nitrogen. This is distinct from the more generally observed Leidenfrost phenomenon that occurs when a liquid droplet is self-vaporized on a hot plate. In the case of rapid cooling, the phase transition from liquid to vitrified solid (i.e., vitrification) and the levitation of droplets on liquid nitrogen (i.e., Leidenfrost phenomenon) take place simultaneously. Here, we investigate these two simultaneous physical events by using a theoretical model containing three dimensionless parameters (i.e., Stefan, Biot, and Fourier numbers). We explain theoretically and observe experimentally a threshold droplet radius during the vitrification of a cryoprotectant droplet in the presence of the Leidenfrost effect.

  9. Colloidal particles embedded in liquid crystal droplets

    NASA Astrophysics Data System (ADS)

    Melchert, Drew; Sadati, Monirosadat; Zhou, Ye; de Pablo, Juan J.

    In this work, we encapsulate polystyrene and silica particles in nematic liquid crystal (LC) droplets dispersed in water using microfluidic glass capillary devices. While polystyrene particles induce planar anchoring on the surface, silica particles, treated with DMOAP, create homeotropic anchoring of the LC molecules at their surface. Sodium dodecyl sulfate (SDS) is added to the aqueous phase to stabilize LC droplets and promote a radial configuration with point defect in the center of LC droplet. Our experimental and computational studies show that, when trapped inside the LC droplets, particles with both anchoring types become mostly localized at the defect point (at the center) and interact with the radial configuration. Interestingly, a twisting structure is observed for polystyrene particle with strong planar anchoring. Although localization of the particles at the droplet center is the most stable state and with the lowest free energy, off-center positions also emerge, displacing the defect point from the center to near the surface of a radial droplet. - Corresponding author - Second affiliation: Argonne National Laboratory, Argonne, IL 60439, USA.

  10. Pressure Effects in Droplet Combustion of Miscible Binary Fuels

    NASA Technical Reports Server (NTRS)

    Mikami, Masato; Habara, Osamu; Kono, Michikata; Sato, Jun-Ichi; Dietrich, Daniel L.; Williams, Forman A.

    1997-01-01

    The objective of this research is to improve understanding of the combustion of binary fuel mixtures in the vicinity of the critical point. Fiber-supported droplets of mixtures of n-heptane and n-hexadecane, initially 1 mm in diameter, were burned in room-temperature air at pressures from 1 MPa to 6 MPa under free-fall microgravity conditions. For most mixtures the total burning time was observed to achieve a minimum value at pressures well above the critical pressure of either of the pure fuels. This behavior is explained in terms of critical mixing conditions of a ternary system consisting of the two fuels and nitrogen. The importance of inert-gas dissolution in the liquid fuel near the critical point is thereby re-emphasized, and nonmonotonic dependence of dissolution on initial fuel composition is demonstrated. The results provide information that can be used to estimate high-pressure burning rates of fuel mixtures.

  11. Heat transfer studies on the liquid droplet radiator

    NASA Technical Reports Server (NTRS)

    Mattick, A. T.; Nelson, M.

    1987-01-01

    This paper examines radiation transfer in the droplet sheet of a liquid droplet radiator including non-isotropic scattering by the droplets. Non-isotropic scattering becomes significant for small droplets (diameter less than 0.1 mm) and for low emissivity liquids. For droplets with an emittance of 0.1 and for a droplet sheet optical depth or 5, the radiated power varies by about 12 percent, depending on whether scattering is predominantly forward or backward. An experimental measurement of the power emitted by a cylindrical cloud of heated droplets of silicone fluid is also reported. The measured cloud emissivity correlates, within experimental error, with the analytical model.

  12. Structural Transitions in Cholesteric Liquid Crystal Droplets.

    PubMed

    Zhou, Ye; Bukusoglu, Emre; Martínez-González, José A; Rahimi, Mohammad; Roberts, Tyler F; Zhang, Rui; Wang, Xiaoguang; Abbott, Nicholas L; de Pablo, Juan J

    2016-07-26

    Confinement of cholesteric liquid crystals (ChLC) into droplets leads to a delicate interplay between elasticity, chirality, and surface energy. In this work, we rely on a combination of theory and experiments to understand the rich morphological behavior that arises from that balance. More specifically, a systematic study of micrometer-sized ChLC droplets is presented as a function of chirality and surface energy (or anchoring). With increasing chirality, a continuous transition is observed from a twisted bipolar structure to a radial spherical structure, all within a narrow range of chirality. During such a transition, a bent structure is predicted by simulations and confirmed by experimental observations. Simulations are also able to capture the dynamics of the quenching process observed in experiments. Consistent with published work, it is found that nanoparticles are attracted to defect regions on the surface of the droplets. For weak anchoring conditions at the nanoparticle surface, ChLC droplets adopt a morphology similar to that of the equilibrium helical phase observed for ChLCs in the bulk. As the anchoring strength increases, a planar bipolar structure arises, followed by a morphological transition to a bent structure. The influence of chirality and surface interactions are discussed in the context of the potential use of ChLC droplets as stimuli-responsive materials for reporting molecular adsorbates.

  13. Simulation of sliding of liquid droplets

    NASA Astrophysics Data System (ADS)

    Alen, Saif Khan; Farhat, Nazia; Rahman, Md. Ashiqur

    2016-07-01

    Numerical simulations of sliding behavior of liquid droplets on flat and periodic microgrooved surfaces with a range of groove geometry are conducted. A numerical model is developed which is capable of predicting the critical sliding angle of the drop by comparing the advancing and the receding angles obtained from numerical and experimental findings. The effect of microgroove topography, droplet size and inclination angle on the droplet sliding characteristics is analysed. Using an open-source platform (Surface Evolver), a 3D drop-shape model is developed to numerically determine the drop stability and contact angle hysteresis on tilted surfaces. In this numerical model, the three phase contact line of the drop is obtained by numerically calculating the vertex force and local contact angle at each vertex of the base contour. Several numerical models are developed based on various assumptions of base contour shape (circular or elliptical) and implementation of gravitational force to the droplet. Droplet shapes and critical sliding angles, obtained from these numerical models, are compared with those of experimental results and are found to be in very good agreement.

  14. Detachment of Liquid-Water Droplets from Gas-Diffusion Layers

    SciTech Connect

    Das, Prodip K.; Grippin, Adam; Weber, Adam Z.

    2011-07-01

    A critical issue for optimal water management in proton-exchange-membrane fuel cells at lower temperatures is the removal of liquid water from the cell. This pathway is intimately linked with the phenomena of liquid-water droplet removal from surface of the gas-diffusion layer and into the flow channel. Thus, a good understanding of liquid-water transport and droplet growth and detachment from the gas-diffusion layer is critical. In this study, liquid-water droplet growth and detachment on the gas-diffusion layer surfaces are investigated experimentally to improve the understating of water transport through and removal from gas-diffusion layers. An experiment using a sliding-angle measurement is designed and used to quantify and directly measure the adhesion force for liquid-water droplets, and to understand the droplets? growth and detachment from the gas-diffusion layers.

  15. Development of comprehensive numerical schemes for predicting evaporating gas-droplets flow processes of a liquid-fueled combustor

    NASA Technical Reports Server (NTRS)

    Chen, C. P.

    1990-01-01

    An existing Computational Fluid Dynamics code for simulating complex turbulent flows inside a liquid rocket combustion chamber was validated and further developed. The Advanced Rocket Injector/Combustor Code (ARICC) is simplified and validated against benchmark flow situations for laminar and turbulent flows. The numerical method used in ARICC Code is re-examined for incompressible flow calculations. For turbulent flows, both the subgrid and the two equation k-epsilon turbulence models are studied. Cases tested include idealized Burger's equation in complex geometries and boundaries, a laminar pipe flow, a high Reynolds number turbulent flow, and a confined coaxial jet with recirculations. The accuracy of the algorithm is examined by comparing the numerical results with the analytical solutions as well as experimented data with different grid sizes.

  16. Numerical Simulations of Droplet Dynamics in PEM Fuel Cell Microchannels

    NASA Astrophysics Data System (ADS)

    Cauble, Eric; Owkes, Mark

    2015-11-01

    Proton exchange membrane (PEM) fuel cells are of beneficial interest due to their capability of producing clean energy with zero emissions. An important design challenge hindering the performance of fuel cells is controlling water removal to maintain a hydrated membrane while avoiding excess water that may lead to channel blockage. Fuel cell water management requires a detailed knowledge of multiphase flow dynamics within microchannels. Direct observation of gas-liquid flows is difficult due to the small scale and viewing obstructions of the channels within the fuel cell. Instead, this work uses a CFD approach to compute the formation and dynamics of droplets in fuel cell channels. The method leverages a conservative volume-of-fluid (VOF) formulation coupled with a novel methodology to track dynamic contact angles. We present details of the numerical approach and simulation results relevant to water management in PEM fuel cells. In particular, it is shown that variation of the contact hysteresis angle influences the wetting properties of the droplet and significantly impacts water transport throughout the a fuel cell channel.

  17. A frictional sliding algorithm for liquid droplets

    NASA Astrophysics Data System (ADS)

    Sauer, Roger A.

    2016-08-01

    This work presents a new frictional sliding algorithm for liquid menisci in contact with solid substrates. In contrast to solid-solid contact, the liquid-solid contact behavior is governed by the contact line, where a contact angle forms and undergoes hysteresis. The new algorithm admits arbitrary meniscus shapes and arbitrary substrate roughness, heterogeneity and compliance. It is discussed and analyzed in the context of droplet contact, but it also applies to liquid films and solids with surface tension. The droplet is modeled as a stabilized membrane enclosing an incompressible medium. The contact formulation is considered rate-independent such that hydrostatic conditions apply. Three distinct contact algorithms are needed to describe the cases of frictionless surface contact, frictionless line contact and frictional line contact. For the latter, a predictor-corrector algorithm is proposed in order to enforce the contact conditions at the contact line and thus distinguish between the cases of advancing, pinning and receding. The algorithms are discretized within a monolithic finite element formulation. Several numerical examples are presented to illustrate the numerical and physical behavior of sliding droplets.

  18. Magnetic-field-induced liquid metal droplet manipulation

    NASA Astrophysics Data System (ADS)

    Kim, Daeyoung; Lee, Jeong-Bong

    2015-01-01

    We report magnetic-field-induced liquid metal droplet on-demand manipulation by coating a liquid metal with ferromagnetic materials. The gallium-based liquid metal alloy has a challenging drawback that it is instantly oxidized in ambient air, resulting in surface wetting on most surfaces. When the oxidized surface of the droplet is coated with ferromagnetic materials, it is non-wettable and can be controlled by applying an external magnetic field. We coated the surface of a liquid metal droplet with either an electroplated CoNiMnP layer or an iron (Fe) particle by simply rolling the liquid metal droplet on an Fe particle bed. For a paper towel, the minimum required magnetic flux density to initiate movement of the ~8 μL Fe-particle-coated liquid metal droplet was 50 gauss. Magnetic-field-induced liquid metal droplet manipulation was investigated under both horizontal and vertical magnetic fields. Compared to the CoNiMnP-electroplated liquid metal droplet, the Fe-particle-coated droplet could be well controlled because Fe particles were uniformly coated on the surface of the droplet. With a maximum applied magnetic flux density of ~1,600 gauss, the CoNiMnP layer on the liquid metal broke down, resulting in fragmentation of three smaller droplets, and the Fe particle was detached from the liquid metal surface and was re-coated after the magnetic field had been removed.

  19. Analysis of transport mechanisms in dense fuel droplet sprays. Final report

    SciTech Connect

    Kleinstreuer, C.

    1991-05-01

    This report deals with numerical analyses of fluid mechanics, heat transfer, mass transfer and particle dynamics of interacting spheres and vaporizing droplets in a linear array or on a 1-D trajectory. Available finite element software has been modified and extended to solve several case studies including closely spaced monodisperse spheres with or without blowing; closely spaced vaporizing fuel droplets; and dynamically interacting vaporizing fuel droplets on a 1-D trajectory. Axisymmetric laminar flow has been assumed for three statically or dynamically interacting spherical solids and vaporizing droplets. Emphasis in this work is evaluating the effects of key system parameters, such as free stream Reynolds number, interparticle spacings, liquid/gas-phase viscosity ratio and variable fluid properties, on interfacial transfer processes and on the particle Nusselt number, vaporization rate and drag coefficient. Computer-generated correlations between integral quantities and system parameters were postulated for blowing spheres and vaporizing droplets. In addition to initial Reynolds number and droplet spacings, variable fluid properties, liquid-phase heating and internal droplet circulation have strong effect on the dynamic behavior of multi-droplet systems. While the lead droplet is most significantly affected by all key parameters, the second and third droplet causes distinct interaction effects which are largely dependent on initial droplet spacings. Applications include spherical-structure/fluid-flow interactions, as well as interacting vaporizing droplets in different sprays related to propulsion systems, irrigation, spray coating, etc. Focusing on fuel droplet sprays, results of the dynamic multi-droplet study can assist in better atomizers and combustion chamber designs which may lead to improved combustion efficiencies, smaller/lighter systems, and reduced pollutant emissions.

  20. Compartmentalized Droplets for Continuous Flow Liquid-Liquid Interface Catalysis.

    PubMed

    Zhang, Ming; Wei, Lijuan; Chen, Huan; Du, Zhiping; Binks, Bernard P; Yang, Hengquan

    2016-08-17

    To address the limitations of batch organic-aqueous biphasic catalysis, we develop a conceptually novel method termed Flow Pickering Emulsion, or FPE, to process biphasic reactions in a continuous flow fashion. This method involves the compartmentalization of bulk water into micron-sized droplets based on a water-in-oil Pickering emulsion, which are packed into a column reactor. The compartmentalized water droplets can confine water-soluble catalysts, thus "immobilizing" the catalyst in the column reactor, while the interstices between the droplets allow the organic (oil) phase to flow. Key fundamental principles underpinning this method such as the oil phase flow behavior, the stability of compartmentalized droplets and the confinement capability of these droplets toward water-soluble catalysts are experimentally and theoretically investigated. As a proof of this concept, case studies including a sulfuric acid-catalyzed addition reaction, a heteropolyacid-catalyzed ring opening reaction and an enzyme-catalyzed chiral reaction demonstrate the generality and versatility of the FPE method. Impressively, in addition to the excellent durability, the developed FPE reactions exhibit up to 10-fold reaction efficiency enhancement in comparison to the existing batch reactions, indicating a unique flow interface catalysis effect. This study opens up a new avenue to allow conventional biphasic catalysis reactions to access more sustainable and efficient flow chemistry using an innovative liquid-liquid interface protocol. PMID:27429173

  1. Dynamics of water droplets detached from porous surfaces of relevance to PEM fuel cells.

    PubMed

    Theodorakakos, A; Ous, T; Gavaises, M; Nouri, J M; Nikolopoulos, N; Yanagihara, H

    2006-08-15

    The detachment of liquid droplets from porous material surfaces used with proton exchange membrane (PEM) fuel cells under the influence of a cross-flowing air is investigated computationally and experimentally. CCD images taken on a purpose-built transparent fuel cell have revealed that the water produced within the PEM is forming droplets on the surface of the gas-diffusion layer. These droplets are swept away if the velocity of the flowing air is above a critical value for a given droplet size. Static and dynamic contact angle measurements for three different carbon gas-diffusion layer materials obtained inside a transparent air-channel test model have been used as input to the numerical model; the latter is based on a Navier-Stokes equations flow solver incorporating the volume of fluid (VOF) two-phase flow methodology. Variable contact angle values around the gas-liquid-solid contact-line as well as their dynamic change during the droplet shape deformation process, have allowed estimation of the adhesion force between the liquid droplet and the solid surface and successful prediction of the separation line at which droplets loose their contact from the solid surface under the influence of the air stream flowing around them. Parametric studies highlight the relevant importance of various factors affecting the detachment of the liquid droplets from the solid surface.

  2. Dynamic interactions of Leidenfrost droplets on liquid metal surface

    NASA Astrophysics Data System (ADS)

    Ding, Yujie; Liu, Jing

    2016-09-01

    Leidenfrost dynamic interaction effects of the isopentane droplets on the surface of heated liquid metal were disclosed. Unlike conventional rigid metal, such conductive and deformable liquid metal surface enables the levitating droplets to demonstrate rather abundant and complex dynamics. The Leidenfrost droplets at different diameters present diverse morphologies and behaviors like rotation and oscillation. Depending on the distance between the evaporating droplets, they attract and repulse each other through the curved surfaces beneath them and their vapor flows. With high boiling point up to 2000 °C, liquid metal offers a unique platform for testing the evaporating properties of a wide variety of liquid even solid.

  3. Numerical simulation of natural convection in a sessile liquid droplet

    NASA Astrophysics Data System (ADS)

    Bartashevich, M. V.; Marchuk, I. V.; Kabov, O. A.

    2012-06-01

    Heat transfer in a sessile liquid droplet was studied with numerical methods. A computer code was developed for solving the problem of convection in an axisymmetric hemispherical droplet and in a spherical layer as well. The problem of establishing an equilibrium state in a droplet was solved using several variables: temperature, stream function, and vorticity. Simulation was performed for droplets of water, ethyl alcohol, and model liquids. Variable parameters: intensity of heat transfer from droplet surface, Rayleigh and Marangoni dimensionless criteria, and the characteristic temperature difference. It was revealed that the curve of convective flow intensity versus heat transfer intensity at droplet surface has a maximum. A dual-vortex structure was obtained in a stationary hemispherical profile of liquid droplet for the case of close values for thermocapillary and thermogravitational forces. Either thermocapillary or thermogravitational vortex might be dominating phenomena in the flow structure.

  4. Superhydrophobic-like tunable droplet bouncing on slippery liquid interfaces

    PubMed Central

    Hao, Chonglei; Li, Jing; Liu, Yuan; Zhou, Xiaofeng; Liu, Yahua; Liu, Rong; Che, Lufeng; Zhou, Wenzhong; Sun, Dong; Li, Lawrence; Xu, Lei; Wang, Zuankai

    2015-01-01

    Droplet impacting on solid or liquid interfaces is a ubiquitous phenomenon in nature. Although complete rebound of droplets is widely observed on superhydrophobic surfaces, the bouncing of droplets on liquid is usually vulnerable due to easy collapse of entrapped air pocket underneath the impinging droplet. Here, we report a superhydrophobic-like bouncing regime on thin liquid film, characterized by the contact time, the spreading dynamics, and the restitution coefficient independent of underlying liquid film. Through experimental exploration and theoretical analysis, we demonstrate that the manifestation of such a superhydrophobic-like bouncing necessitates an intricate interplay between the Weber number, the thickness and viscosity of liquid film. Such insights allow us to tune the droplet behaviours in a well-controlled fashion. We anticipate that the combination of superhydrophobic-like bouncing with inherent advantages of emerging slippery liquid interfaces will find a wide range of applications. PMID:26250403

  5. Dynamic behaviors of liquid droplets on a gas diffusion layer surface: Hybrid lattice Boltzmann investigation

    NASA Astrophysics Data System (ADS)

    Wu, Jie; Huang, Jun-Jie

    2015-07-01

    Water management is one of the key issues in proton exchange membrane fuel cells. Fundamentally, it is related to dynamic behaviors of droplets on a gas diffusion layer (GDL) surface, and consequently they are investigated in this work. A two-dimensional hybrid method is employed to implement numerical simulations, in which the flow field is solved by using the lattice Boltzmann method and the interface between droplet and gas is captured by solving the Cahn-Hilliard equation directly. One or two liquid droplets are initially placed on the GDL surface of a gas channel, which is driven by the fully developed Poiseuille flow. At a fixed channel size, the effects of viscosity ratio of droplet to gas ( μ ∗ ), Capillary number (Ca, ratio of gas viscosity to surface tension), and droplet interaction on the dynamic behaviors of droplets are systematically studied. By decreasing viscosity ratio or increasing Capillary number, the single droplet can detach from the GDL surface easily. On the other hand, when two identical droplets stay close to each other or a larger droplet is placed in front of a smaller droplet, the removal of two droplets is promoted.

  6. Blue-phase liquid crystal droplets

    PubMed Central

    Martínez-González, José A.; Zhou, Ye; Rahimi, Mohammad; Bukusoglu, Emre; Abbott, Nicholas L.; de Pablo, Juan J.

    2015-01-01

    Blue phases of liquid crystals represent unique ordered states of matter in which arrays of defects are organized into striking patterns. Most studies of blue phases to date have focused on bulk properties. In this work, we present a systematic study of blue phases confined into spherical droplets. It is found that, in addition to the so-called blue phases I and II, several new morphologies arise under confinement, with a complexity that increases with the chirality of the medium and with a nature that can be altered by surface anchoring. Through a combination of simulations and experiments, it is also found that one can control the wavelength at which blue-phase droplets absorb light by manipulating either their size or the strength of the anchoring, thereby providing a liquid–state analog of nanoparticles, where dimensions are used to control absorbance or emission. The results presented in this work also suggest that there are conditions where confinement increases the range of stability of blue phases, thereby providing intriguing prospects for applications. PMID:26460039

  7. The design and performance of a multi-stream droplet generator for the liquid droplet radiator

    NASA Technical Reports Server (NTRS)

    Orme, Melissa; Farnham, T.; Van Diep, G. Pham; Muntz, E. P.; White, Alan

    1987-01-01

    Results are presented for the performance capabilities of a multistream droplet generator suitable for use in a spacecraft liquid droplet radiator heat-rejection system. The nozzle-motion mode of stream perturbation initiation was tested with a single droplet stream and found to produce data similar to those generated with the resonant cavity mode of perturbation. Tests then proceeded to a 26-orifice array; the streams of the array responded to the perturbation satisfactorily, forming uniformly separated drops.

  8. Structure of liquid crystal droplets with chiral propeller texture.

    PubMed

    Yang, Deng-Ke; Jeong, Kwang-Un; Cheng, S Z D

    2008-02-01

    We experimentally studied a nematic liquid crystal whose molecules form twisted head-to-head H-bonded dimers. We observed that when the material transformed from the isotropic to nematic phase, it formed droplets with chiral propeller textures. We carried out a computer simulation to investigate the liquid crystal director configuration inside the droplets and to study the effects of elastic constants and chirality on the droplet texture. Results of our study show it is likely that the material in the droplets had nonzero chirality due to spontaneous chiral phase separation.

  9. Fuel droplet burning rates at high pressures.

    NASA Technical Reports Server (NTRS)

    Canada, G. S.; Faeth, G. M.

    1973-01-01

    Combustion of methanol, ethanol, propanol-1, n-pentane, n-heptane, and n-decane was observed in air under natural convection conditions, at pressures up to 100 atm. The droplets were simulated by porous spheres, with diameters in the range from 0.63 to 1.90 cm. The pressure levels of the tests were high enough so that near-critical combustion was observed for methanol and ethanol. Due to the high pressures, the phase-equilibrium models of the analysis included both the conventional low-pressure approach as well as high-pressure versions, allowing for real gas effects and the solubility of combustion-product gases in the liquid phase. The burning-rate predictions of the various theories were similar, and in fair agreement with the data. The high-pressure theory gave the best prediction for the liquid-surface temperatures of ethanol and propanol-1 at high pressure. The experiments indicated the approach of critical burning conditions for methanol and ethanol at pressures on the order of 80 to 100 atm, which was in good agreement with the predictions of both the low- and high-pressure analysis.

  10. Liquid droplet radiator program at the NASA Lewis Research Center

    NASA Technical Reports Server (NTRS)

    Presler, A. F.; Coles, C. E.; Diem-Kirsop, P. S.; White, K. A., III

    1985-01-01

    The NASA Lewis Research Center and the Air Force Rocket Propulsion Laboratory (AFRPL) are jointly engaged in a program for technical assessment of the Liquid Droplet Radiator (LDR) concept as an advanced high performance heat ejection component for future space missions. NASA Lewis has responsibility for the technology needed for the droplet generator, for working fluid qualification, and for investigating the physics of droplets in space; NASA Lewis is also conducting systems/mission analyses for potential LDR applications with candidate space power systems. For the droplet generator technology task, both micro-orifice fabrication techniques and droplet stream formation processes have been experimentally investigated. High quality micro-orifices (to 50 micron diameter) are routinely fabricated with automated equipment. Droplet formation studies have established operating boundaries for the generation of controlled and uniform droplet streams. A test rig is currently being installed for the experimental verification, under simulated space conditions, of droplet radiation heat transfer performance analyses and the determination of the effect radiative emissivity of multiple droplet streams. Initial testing has begun in the NASA Lewis Zero-Gravity Facility for investigating droplet stream behavior in microgravity conditions. This includes the effect of orifice wetting on jet dynamics and droplet formation. Results for both Brayton and Stirling power cycles have identified favorable mass and size comparisons of the LDR with conventional radiator concepts.

  11. The Role of Liquid Properties on Lifetime of Levitated Droplets.

    PubMed

    Davanlou, Ashkan

    2016-09-27

    It is known that the temperature difference between a droplet and a liquid surface can extend the levitation time of that droplet by providing a thin air film between the surface and the droplet. However, the effect of fluid properties, liquid surface velocity, and air film thickness on the lifetime of droplets is still not well understood. Also, there is inconsistency in the literature about the role of vapor pressure in noncoalescence. Here we test a variety of liquids including silicone oil, Fluorinert, and water to understand the effect of surface tension, density ratio, viscosity, and heat capacity on the lifetime of a droplet. Droplets with larger heat capacity and vapor pressure like water remain floating for a longer time compared to oils. Similarly, higher surface velocity, which is seen in low viscous liquids, helps the air to replenish into the interstices beneath droplet and delay the drainage process. We also discuss the air film variation with temperature manipulation, and propose a correlation for the minimum thickness required to balance the droplet weight. PMID:27579853

  12. Experimental analysis and semicontinuous simulation of low-temperature droplet evaporation of multicomponent fuels

    NASA Astrophysics Data System (ADS)

    Lehmann, S.; Lorenz, S.; Rivard, E.; Brüggemann, D.

    2015-01-01

    Low-pollutant and efficient combustion not only in internal combustion engines requires a balanced gaseous mixture of fuel and oxidizer. As fuels may contain several hundred different chemical species with different physicochemical properties as well as defined amounts of biogenic additives, e.g., ethanol, a thorough understanding of liquid fuel droplet evaporation processes is necessary to allow further engine optimization. We have studied the evaporation of fuel droplets at low ambient temperature. A non-uniform temperature distribution inside the droplet was already considered by including a finite thermal conductivity in a one-dimensional radial evaporation model (Rivard and Brüggemann in Chem Eng Sci 65(18):5137-5145, 2010). For a detailed analysis of droplet evaporation, two non-laser-based experimental setups have been developed. They allow a fast and relatively simple but yet precise measurement of diameter decrease and composition change. The first method is based on collecting droplets in a diameter range from 70 to 150 µm by a high-precision scale. A simultaneous evaluation of mass increase is employed for an accurate average diameter value determination. Subsequently, a gas chromatographic analysis of the collected droplets was conducted. In the second experiment, evaporation of even smaller droplets was optically analyzed by a high-speed shadowgraphy/schlieren microscope setup. A detailed analysis of evaporating E85 (ethanol/gasoline in a mass ratio of 85 %/15 %) and surrogate fuel droplets over a wide range of initial droplet diameters and ambient temperatures was conducted. The comparison of experimental and numerical results shows the applicability of the developed model over a large range of diameters and temperatures.

  13. Liquid droplet radiators for heat rejection in space

    NASA Technical Reports Server (NTRS)

    Mattick, A. T.; Hertzberg, A.

    1980-01-01

    A radiator for heat rejection in space is described which utilizes a stream of liquid droplets to radiate waste heat. The large surface area per mass makes the liquid droplet radiator at least an order of magnitude lighter than tube and fin radiators. Generation and collection of the droplets, as well as heat transfer to the liquid, can be achieved with modest extensions of conventional technology. Low vapor pressure liquids are available which cover a radiating temperature range 250-1000 K with negligible evaporation losses. The droplet radiator may be employed for a wide range of heat rejection applications in space. Three applications - heat rejection for a high temperature Rankine cycle, cooling of photovoltaic cells, and low temperature heat rejection for refrigeration in space illustrate the versatility of the radiator.

  14. Experimental Study of Unsupported Nonane fuel Droplet Combustion in Microgravity

    NASA Technical Reports Server (NTRS)

    Callahan, B. J.; Avedisian, C. T.; Hertzog, D. E.; Berkery, J. W.

    1999-01-01

    Soot formation in droplet flames is the basic component of the particulate emission process that occurs in spray combustion. The complexity of soot formation motivates a one-dimensional transport condition which has obvious advantages in modeling. Recent models of spherically symmetric droplet combustion have made this assumption when incorporating such aspects as detailed chemistry and radiation. Interestingly, spherical symmetry does not necessarily restrict the results because it has been observed that the properties of carbon formed in flames are not strongly affected by the nature of the fuel or flaming configuration. What is affected, however, are the forces acting on the soot aggregates and where they are trapped by a balance of drag and thermophoretic forces. The distribution of these forces depends on the transport conditions of the flame. Prior studies of spherical droplet flames have examined the droplet burning history of alkanes, alcohols and aromatics. Data are typically the evolution of droplet, flame, extinction, and soot shell diameters. These data are only now just beginning to find their way into comprehensive numerical models of droplet combustion to test proposed oxidation schemes for fuels such as methanol and heptane. In the present study, we report new measurements on the burning history of unsupported nonane droplets in a convection-free environment to promote spherical symmetry. The far-field gas is atmospheric pressure air at room temperature. The evolution of droplet diameter was measured using high speed cine photography of a spark-ignited, droplet within a confined volume in a drop tower. The initial droplet diameters varied between 0.5 mm and 0.6 mm. The challenge of unsupported droplets is to form, deploy and ignite them with minimal disturbance, and then to keep them in the camera field of view. Because of the difficulty of this undertaking, more sophisticated diagnostics for studying soot than photographic were not used. Supporting

  15. Droplets on liquids and their journey into equilibrium.

    PubMed

    Bommer, Stefan; Cartellier, Florian; Jachalski, Sebastian; Peschka, Dirk; Seemann, Ralf; Wagner, Barbara

    2013-08-01

    The morphological path of droplets on a liquid substrate towards equilibrium is investigated experimentally and theoretically. The droplets emerge in the late stage of a dewetting process of short chained polystyrene (PS) dewetting from liquid polymethyl-methacrylate (PMMA). The three-dimensional droplet profiles are obtained experimentally by combining the in situ imaged PS/air interface during equilibration and the ex situ imaged PS/PMMA interface after removal of the PS by a selective solvent. Numerically the transient drop shapes are calculated by solving the thin-film equation in lubrication approximation using the experimentally determined input parameter like viscosity, film thickness and surface tensions. The numerically obtained droplet morphologies and time scales agree very well with the experimental drop shapes. An unexpected observation is that droplets with identical volumes synchronise their motion and become independent of the initial geometry long time before equilibrium is reached. PMID:23933987

  16. The internal caustic structure of illuminated liquid droplets

    NASA Technical Reports Server (NTRS)

    Lock, James A.; Hovenac, Edward A.

    1991-01-01

    The internal electric field of an illuminated liquid droplet is studied in detail using both wave theory and ray theory. The internal field obtains its maximum values on the caustics within the droplet. Ray theory is used to determine the equations of these caustics and the density of rays on them. The Debye series expansion of the interior field Mie amplitudes is used to calculate the wave theory version of these caustics. The physical interpretation of the sources of stimulated Raman scattering and fluorescence emission within a liquid droplet is then given.

  17. Liquid fuel cells.

    PubMed

    Soloveichik, Grigorii L

    2014-01-01

    The advantages of liquid fuel cells (LFCs) over conventional hydrogen-oxygen fuel cells include a higher theoretical energy density and efficiency, a more convenient handling of the streams, and enhanced safety. This review focuses on the use of different types of organic fuels as an anode material for LFCs. An overview of the current state of the art and recent trends in the development of LFC and the challenges of their practical implementation are presented.

  18. Liquid fuel cells

    PubMed Central

    2014-01-01

    Summary The advantages of liquid fuel cells (LFCs) over conventional hydrogen–oxygen fuel cells include a higher theoretical energy density and efficiency, a more convenient handling of the streams, and enhanced safety. This review focuses on the use of different types of organic fuels as an anode material for LFCs. An overview of the current state of the art and recent trends in the development of LFC and the challenges of their practical implementation are presented. PMID:25247123

  19. Fabrication of hemispherical liquid encapsulated structures based on droplet molding

    NASA Astrophysics Data System (ADS)

    Ishizuka, Hiroki; Miki, Norihisa

    2015-12-01

    We have developed and demonstrated a method for forming spherical structures of a thin polydimethylsiloxane (PDMS) membrane encapsulating a liquid. Liquid encapsulation can enhance the performance of microelectromechanical systems (MEMS) devices by providing deformability and improved dielectric properties. Parylene deposition and wafer bonding are applied to encapsulate liquid into a MEMS device. In parylene deposition, a parylene membrane is directly formed onto a liquid droplet. However, since the parylene membrane is stiff, the membrane is fragile. Although wafer bonding can encapsulate liquid between two substrates, the surface of the fabricated structure is normally flat. We propose a new liquid encapsulation method by dispensing liquid droplets. At first, a 20 μl PDMS droplet is dispensed on ethylene glycol. A 70 μl glycerin droplet is dispensed into a PDMS casting solution layer. The droplet forms a layer on heated ethylene glycol. Glycerin and ethylene glycol are chosen for their high boiling points. Additionally, a glycerin droplet is dispensed on the layer and surrounded by a thin PDMS casting solution film. The film is baked for 1 h at 75 °C. As the result, a structure encapsulating a liquid in a flexible PDMS membrane is obtained. We investigate the effects of the volume, surface tension, and guide thickness on the shape of the formed structures. We also evaluated the effect of the structure diameter on miniaturization. The structure can be adapted for various functions by changing the encapsulated liquid. We fabricated a stiffness-tunable structure by dispensing a magnetorheoligical fluid droplet with a stiffness that can be changed by an external magnetic field. We also confirmed that the proposed structure can produce stiffness differences that are distinguishable by humans.

  20. Liquid Droplet Dynamics in Gravity Compensating High Magnetic Field

    NASA Technical Reports Server (NTRS)

    Bojarevics, V.; Easter, S.; Pericleous, K.

    2012-01-01

    Numerical models are used to investigate behavior of liquid droplets suspended in high DC magnetic fields of various configurations providing microgravity-like conditions. Using a DC field it is possible to create conditions with laminar viscosity and heat transfer to measure viscosity, surface tension, electrical and thermal conductivities, and heat capacity of a liquid sample. The oscillations in a high DC magnetic field are quite different for an electrically conducting droplet, like liquid silicon or metal. The droplet behavior in a high magnetic field is the subject of investigation in this paper. At the high values of magnetic field some oscillation modes are damped quickly, while others are modified with a considerable shift of the oscillating droplet frequencies and the damping constants from the non-magnetic case.

  1. Retreating behavior of a charged ionic liquid droplet in a dielectric liquid under electric field

    NASA Astrophysics Data System (ADS)

    Ahn, Myung Mo; Im, Do Jin; Kang, In Seok

    2013-11-01

    Ionic liquids show great promise as excellent solvents or catalysts in energy and biological fields due to their unique chemical and physical properties. The ionic liquid droplets in microfluidic systems can also be used as a potential platform for chemical biological reactions. In order to control electrically the ionic liquid droplets in a microfluidic device, the charging characteristics of ionic liquid droplets need to be understood. In this work, the charging characteristics of various ionic liquids are investigated by using the parallel plate electrodes system. Under normal situation, a charged droplet shows bouncing motion between electrodes continuously. However, for some special ionic liquids, interesting retreating behavior of charged ionic liquid droplet has been observed. This retreating behavior of ionic liquid droplet has been analyzed experimentally by the image analysis and the electrometer signal analysis. Based on the hypothesis of charge leakage of the retreating ionic liquid droplets, FT-IR spectroscopy analysis has also been performed. The retreating behavior of ionic liquid droplet is discussed from the intermolecular point of view according to the species of ionic liquids. This research was supported by grant No. 2013R1A1A2011956 funded by the Ministry of Science, ICT and Future Planning (MSIP) and by grant No. 2013R1A1A2010483 funded by the Ministry of Education, Science and Technology (MEST) through the NRF.

  2. Active Mesogenic Droplets: Impact of Liquid Crystallinity and Collective Behavior

    NASA Astrophysics Data System (ADS)

    Bahr, Christian

    Droplets of common mesogenic compounds show a self-propelled motion when immersed in aqueous solutions containing ionic surfactants at concentrations well above the critical micelle concentration. After introducing some general properties of this type of artificial microswimmer, we focus on two topics: the influence of liquid crystallinity on the swimming behavior and the collective behavior of ensembles of a larger number of droplets. The mesogenic properties are not essential for the basic mechanism of self-propulsion, nevertheless they considerably influence the swimming behavior of the droplets. For instance, the shape of the trajectories strongly depends on whether the droplets are in the nematic or isotropic state. The droplet swimmers are also ideally suited for the study of collective behavior: Microfluidics enables the generation of large numbers of identical swimmers and we can tune their buoyancy. We report on the collective behavior in three-dimensional environments. Supported by the Deutsche Forschungsgemeinschaft (SPP 1726 ``Microswimmers'').

  3. Nano Liquid Crystal Droplet Impact on Solid Surfaces

    NASA Astrophysics Data System (ADS)

    Zhang, Rui; de Pablo, Juan; dePablo Team

    2015-03-01

    Liquid droplet impaction on solid surfaces is an important problem with a wide range of applications in everyday life. Liquid crystals (LCs) are anisotropic liquids whose internal structure gives rise to rich optical and morphological phenomena. In this work we study the liquid crystal droplet impaction on solid surfaces by molecular dynamics simulations. We employ a widely used Gay-Berne model to describe the elongated liquid crystal molecules and their interactions. Our work shows that, in contrast to isotropic liquids, drop deformation is symmetric unless an instability kicks in, in which case a nano scale liquid crystal droplet exhibits distinct anisotropic spreading modes that do not occur in simple liquids. The drop prefers spreading along the low viscosity direction, but inertia can in some cases overcome that bias. The effects of the director field of the droplet, preferred anchoring direction and the anchoring strength of the wall are investigated. Large scale (0.1 micron) simulations are performed to connect our nano scale results to the experiments. Our studies indicate that LCs could provide an interesting alternative for development of next-generation printing inks.

  4. Droplet impact on highly viscous liquid: from experiments to numerics

    NASA Astrophysics Data System (ADS)

    Jian, Zhen; Michon, Guy-Jean; Josserand, Christophe; Zaleski, Stephane; Ray, Pascal; Li, Zengyao; Tao, Wenquan

    2014-11-01

    A numerical model is proposed to deal with the triple-phase impacting dynamics, of which a droplet of normal liquid impacts on a highly viscous liquid basin. Viscous effect is dominant during the dynamics as compared to the inertia and the surface tension. A liquid viscosity ratio ml is introduced to measure the viscosity deviation from a normal liquid as ml =μbasin /μdrople normal . Direct numerical simulations were executed with a code called Gerris. By increasing the liquid viscosity ratio ml, a continuous transition from L / L impact to L / S impact can be achieved. Two regimes are identified: wave-like regime and solidification regime. Experiments of droplet impacting on highly viscous liquid were also executed. Droplets of ethanol impact on a liquid basin of honey in a vacuum chamber where the gas pressure could be varied. A similarity to the impact on solid was observed, liquid basin performed as a solid and the complete suppression of splash was also observed by decreasing the gas pressure as reported for impacts on solid. Droplet shapes predicted by our simulations agree well with those observed in experiments.

  5. Optical Fluctuation of Texture in Nematic Liquid Crystal Droplets

    NASA Astrophysics Data System (ADS)

    Kim, Sung-Jo; Back, Sang-In; Lev, Bohdan; Kim, Jong-Hyun

    2016-07-01

    We report the observation of texture of a nematic liquid crystal droplet using a high-speed camera mounted on a polarizing optical microscope. The dark crossed texture obtained by the polarizing optical microscope of a nematic liquid crystal droplet has texture wobbles, which are related to the director field fluctuation excited by thermal energy. We confirm relaxation and oscillation modes. An exact solution of the director fluctuation modes with one-constant approximation and an external electric field is proposed. The theoretical predictions of the relaxation time match with our experimental results when varying the temperature, droplet size, and electric field. Relaxation time was insensitive to the temperature, increased with radius of droplet and slightly decreased with electric field. Several oscillation modes, which have no specific trend, were also found. The external electric field freezes the oscillation modes.

  6. Impact of droplets on inclined flowing liquid films

    NASA Astrophysics Data System (ADS)

    Che, Zhizhao; Deygas, Amandine; Matar, Omar K.

    2015-08-01

    The impact of droplets on an inclined falling liquid film is studied experimentally using high-speed imaging. The falling film is created on a flat substrate with controllable thicknesses and flow rates. Droplets with different sizes and speeds are used to study the impact process under various Ohnesorge and Weber numbers, and film Reynolds numbers. A number of phenomena associated with droplet impact are identified and analyzed, such as bouncing, partial coalescence, total coalescence, and splashing. The effects of droplet size, speed, as well the film flow rate are studied culminating in the generation of an impact regime map. The analysis of the lubrication force acted on the droplet via the gas layer shows that a higher flow rate in the liquid film produces a larger lubrication force, slows down the drainage process, and increases the probability of droplet bouncing. Our results demonstrate that the flowing film has a profound effect on the droplet impact process and associated phenomena, which are markedly more complex than those accompanying impact on initially quiescent films.

  7. Status of liquid droplet radiator systems analysis techniques

    SciTech Connect

    Brandell, B.; Feig, J.R.; Francis, R.; Matlock, R.S.; Taussig, R.T.

    1984-08-01

    This paper presents the status of several efforts aimed at developing analysis and design tests for liquid droplet radiators (LDRs). A variable metric optimizer, which is being developed to merge with the model, increases the versatility of the LDR system analysis code and allows the determination of maximum power per unit mass. A developmental thermal radiation model that will be incorporated into the systems analysis. The model provides temperature histories and distributions within the sheet as the droplets travel from generator to collector.

  8. A realistic model of evaporation for a liquid droplet

    NASA Technical Reports Server (NTRS)

    Chai, An-Ti; Arpaci, V. S.

    1994-01-01

    An intuitive delineation along with dimensional considerations and experimental evidences are presented to show that in a general case, the evaporation of a liquid droplet undergoes three regimes through the process. Initially, the heat transfer inside the evaporating droplets is conduction controlled; then, in the second stage, convective heat transfer may take over; finally, the convections subside, and the process returns to conduction controlled mode.

  9. Nontoxic Ionic Liquid Fuels for Exploration Applications

    NASA Technical Reports Server (NTRS)

    Coil, Millicent

    2015-01-01

    The toxicity of propellants used in conventional propulsion systems increases not only safety risks to personnel but also costs, due to special handling required during the entire lifetime of the propellants. Orbital Technologies Corporation (ORBITEC) has developed and tested novel nontoxic ionic liquid fuels for propulsion applications. In Phase I of the project, the company demonstrated the feasibility of several ionic liquid formulations that equaled the performance of conventional rocket propellant monomethylhydrazine (MMH) and also provided low volatility and low toxicity. In Phase II, ORBITEC refined the formulations, conducted material property tests, and investigated combustion behavior in droplet and microreactor experiments. The company also explored the effect of injector design on performance and demonstrated the fuels in a small-scale thruster. The ultimate goal is to replace propellants such as MMH with fuels that are simultaneously high-performance and nontoxic. The fuels will have uses in NASA's propulsion applications and also in a range of military and commercial functions.

  10. Secondary atomization of single coal-water fuel droplets

    SciTech Connect

    Hassel, G.R.; Scaroni, A.W.

    1989-03-01

    The evaporative behavior of single, well characterized droplets of a lignite coal-water slurry fuel (CWSF) and a carbon black in water slurry was studied as a function of heating rate and droplet composition. Induced droplet heating rates were varied from 0 to 10{sup 5} K/s. Droplets studied were between 97 and 170 {mu}m in diameter, with compositions ranging from 25 to 60% solids by weight. The effect of a commercially available surfactant additive package on droplet evaporation rate, explosive boiling energy requirements, and agglomerate formation was assessed. Surfactant concentrations were varied from none to 2 and 4% by weight solution (1.7 and 3.6% by weight of active species on a dry coal basis). The experimental system incorporated an electrodynamic balance to hold single, free droplets, a counterpropagating pulsed laser heating arrangement, and both video and high speed cinematographic recording systems. Data were obtained for ambient droplet evaporation by monitoring the temporal size, weight, and solids concentration changes. 49 refs., 31 figs.

  11. Conceptual design of liquid droplet radiator shuttle-attached experiment

    NASA Technical Reports Server (NTRS)

    Pfeiffer, Shlomo L.

    1989-01-01

    The conceptual design of a shuttle-attached liquid droplet radiator (LDR) experiment is discussed. The LDR is an advanced, lightweight heat rejection concept that can be used to reject heat from future high-powered space platforms. In the LDR concept, submillimeter-sized droplets are generated, pass through space, radiate heat before they are collected, and recirculated back to the heat source. The LDR experiment is designed to be attached to the shuttle longeron and integrated into the shuttle bay using standard shuttle/experiment interfaces. Overall power, weight, and data requirements of the experiment are detailed. The conceptual designs of the droplet radiator, droplet collector, and the optical diagnostic system are discussed in detail. Shuttle integration and safety design issues are also discussed.

  12. Investigation of water droplet dynamics in PEM fuel cell gas channels

    NASA Astrophysics Data System (ADS)

    Gopalan, Preethi

    Water management in Proton Exchange Membrane Fuel Cell (PEMFC) has remained one of the most important issues that need to be addressed before its commercialization in automotive applications. Accumulation of water on the gas diffusion layer (GDL) surface in a PEMFC introduces a barrier for transport of reactant gases through the GDL to the catalyst layer. Despite the fact that the channel geometry is one of the key design parameters of a fluidic system, very limited research is available to study the effect of microchannel geometry on the two-phase flow structure. In this study, the droplet-wall dynamics and two-phase pressure drop across the water droplet present in a typical PEMFC channel, were examined in auto-competitive gas channel designs (0.4 x 0.7 mm channel cross section). The liquid water flow pattern inside the gas channel was analyzed for different air velocities. Experimental data was analyzed using the Concus-Finn condition to determine the wettability characteristics in the corner region. It was confirmed that the channel angle along with the air velocity and the channel material influences the water distribution and holdup within the channel. Dynamic contact angle emerged as an important parameter in controlling the droplet-wall interaction. Experiments were also performed to understand how the inlet location of the liquid droplet on the GDL surface affects the droplet dynamic behavior in the system. It was found that droplets emerging near the channel wall or under the land lead to corner filling of the channel. Improvements in the channel design has been proposed based on the artificial channel roughness created to act as capillary grooves to transport the liquid water away from the land area. For droplets emerging near the center of the channel, beside the filling and no-filling behavior reported in the literature, a new droplet jumping behavior was observed. As droplets grew and touched the sidewalls, they jumped off to the sidewall leaving the

  13. Multiscale Simulation of Gas Film Lubrication During Liquid Droplet Collision

    NASA Astrophysics Data System (ADS)

    Chen, Xiaodong; Khare, Prashant; Ma, Dongjun; Yang, Vigor

    2012-02-01

    Droplet collision plays an elementary role in dense spray combustion process. When two droplets approach each other, a gas film forms in between. The pressure generated within the film prevents motion of approaching droplets. This fluid mechanics is fluid film lubrication that occurs when opposing bearing surfaces are completely separated by fluid film. The lubrication flow in gas film decides the collision outcome, coalescence or bouncing. Present study focuses on gas film drainage process over a wide range of Weber numbers during equal- and unequal-sized droplet collision. The formulation is based on complete set of conservation equations for both liquid and surrounding gas phases. An improved volume-of-fluid technique, augmented by an adaptive mesh refinement algorithm, is used to track liquid/gas interfaces. A unique thickness-based refinement algorithm based on topology of interfacial flow is developed and implemented to efficiently resolve the multiscale problem. The grid size on interface is up O(10-4) of droplet size with a max resolution of 0.015 μm. An advanced visualization technique using the Ray-tracing methodology is used to gain direct insights to detailed physics. Theories are established by analyzing the characteristics of shape changing and flow evolution.

  14. Evaporation and burning of a spherical fuel droplet in a uniform convective flowfield

    SciTech Connect

    Madooglu, K.

    1992-01-01

    An analytical/numerical model is developed for the evaporation and burning of a spherical fuel droplet in a subsonic crossflow. The external gaseous flowfield is represented using an approximate compressible potential-flow solution, while the internal flowfield of the droplet is represented by the classical Hill's spherical vortex. This allows a numerical solution for the external boundary layer, from which the droplet's effective drag coefficent, rate of mass loss, size, and the shape of the diffusion flame with infinitely fast chemical reaction kinetics are determined. Subsequently, the quasi-steady model with uniform liquid temperature is extended to examine the effects of the transient heating of the droplet interior. Time-dependent calculations are performed with updated droplet Reynolds numbers and updated surface temperatures. Comparisons of model predictions with experimental data are made. To examine the effects of finite-rate chemical reaction kinetics, a one-step formulation of the combustion mechanism is integrated into the gaseous boundary layer equations. Simplifying assumptions for the variation of gas properties commonly used in combustion calculations, are subjected to an examination as to their degree of accuracy. For this purpose, the droplet model is extended to account for the variation of gas properties with temperature and gas composition within the boundary layer. Comparisons are made between the predictions obtained from the different models developed in this study, as well as with existing experimental data.

  15. Intrusion of a Liquid Droplet into a Powder under Gravity.

    PubMed

    Boyce, C M; Ozel, A; Sundaresan, S

    2016-08-30

    Intrusion of a liquid droplet into a hexagonal close-packed array of spheres under gravity is investigated using analytical methods and volume-of-fluid simulations. Four regimes of ultimate fluid behavior are identified: (A) no liquid imbibition into the bed, (B) trapping of liquid high in the bed, (C) liquid descending to the bottom of the bed, and (D) liquid spreading around the surface of all particles. These regimes are mapped based on the contact angle and Bond number of the system. Many aspects of the dynamics and ultimate liquid behavior are captured using a simplified model of a mass of liquid moving under gravity in a vertical capillary of undulating cross-sectional area. This simplified model is used to form momentum transport equations with four forms of nondimensional time, which are shown to collapse the simulation data with different fluid parameters in different regimes. PMID:27487358

  16. Isolated Liquid Droplet Combustion: Inhibition and Extinction Studies

    NASA Technical Reports Server (NTRS)

    Dryer, F. L.; Kroenlein, K. G.; Kazakov, A.; Williams, F. A.; Nayagam, V.

    2004-01-01

    Introduction of fire suppressants to the ambient environment surrounding a heterogeneous diffusion flame may be an inefficient technique for fire safety in systems without buoyant flows. Carbon dioxide substitution for nitrogen diluent leads to significant modifications of the sphero-symmetric burning behavior of isolated n-heptane droplets, partly through increased heat capacity within the gaseous diffusion flame, but mostly because of modifications in spectral radiative coupling in the gas phase. Effects of longer time scale phenomena such as sooting and slow gas-phase/droplet convection remain to be determined. Similar methodologies can be applied to evaluate the effects and efficacy of chemical inhibitors in the liquid and gas phases.

  17. Micromachined ultrasonic droplet generator based on a liquid horn structure

    NASA Astrophysics Data System (ADS)

    Meacham, J. M.; Ejimofor, C.; Kumar, S.; Degertekin, F. L.; Fedorov, A. G.

    2004-05-01

    A micromachined ultrasonic droplet generator is developed and demonstrated for drop-on-demand fluid atomization. The droplet generator comprises a bulk ceramic piezoelectric transducer for ultrasound generation, a reservoir for the ejection fluid, and a silicon micromachined liquid horn structure as the nozzle. The nozzles are formed using a simple batch microfabrication process that involves wet etching of (100) silicon in potassium hydroxide solution. Device operation is demonstrated by droplet ejection of water through 30 μm orifices at 1.49 and 2.30 MHz. The finite-element simulations of the acoustic fields in the cavity and electrical impedance of the device are in agreement with the measurements and indicate that the device utilizes cavity resonances in the 1-5 MHz range in conjunction with acoustic wave focusing by the pyramidally shaped nozzles to achieve low power operation.

  18. Glucose sensor using liquid-crystal droplets made by microfluidics.

    PubMed

    Kim, Jiyeon; Khan, Mashooq; Park, Soo-Young

    2013-12-26

    Micrometer-sized, 4-cyno-4-pentylbiphenyl (5CB) droplets were developed for glucose detection in an aqueous medium by coating with poly(acrylicacid-b-4-cynobiphenyl-4-oxyundecylacrylate) (PAA-b-LCP) at the 5CB/water interface and covalently immobilizing glucose oxidase (GOx) to the PAA chains. This functionalized liquid-crystal (LC) droplet detected glucose from a radial to bipolar configurational change by polarized optical microscopy under crossed polarizers at concentrations as low as 0.03 mM and response times of ~3 min and showed the selective detection of glucose against galactose. This new and sensitive LC-droplet-based glucose biosensor has the merits of low production cost and easy detection by the naked eye and might be useful for prescreening the glucose level in the human body. PMID:24251831

  19. Endotoxin-Induced Structural Transformations in Liquid Crystalline Droplets

    NASA Astrophysics Data System (ADS)

    Lin, I.-Hsin; Miller, Daniel S.; Bertics, Paul J.; Murphy, Christopher J.; de Pablo, Juan J.; Abbott, Nicholas L.

    2011-06-01

    The ordering of liquid crystals (LCs) is known to be influenced by surfaces and contaminants. Here, we report that picogram per milliliter concentrations of endotoxin in water trigger ordering transitions in micrometer-size LC droplets. The ordering transitions, which occur at surface concentrations of endotoxin that are less than 10-5 Langmuir, are not due to adsorbate-induced changes in the interfacial energy of the LC. The sensitivity of the LC to endotoxin was measured to change by six orders of magnitude with the geometry of the LC (droplet versus slab), supporting the hypothesis that interactions of endotoxin with topological defects in the LC mediate the response of the droplets. The LC ordering transitions depend strongly on glycophospholipid structure and provide new designs for responsive soft matter.

  20. Dielectrophoresis-driven spreading of immersed liquid droplets.

    PubMed

    Brown, Carl V; McHale, Glen; Trabi, Christophe L

    2015-01-27

    In recent years electrowetting-on-dielectric (EWOD) has become an effective tool to control partial wetting. EWOD uses the liquid-solid interface as part of a capacitive structure that allows capacitive and interfacial energies to adjust by changes in wetting when the liquid-solid interface is charged due to an applied voltage. An important aspect of EWOD has been its applications in microfluidics in chemistry and biology and in optical devices and displays in physics and engineering. Many of these rely on the use of a liquid droplet immersed in a second liquid due to the need either for neutral buoyancy to overcome gravity and shield against impact shocks or to encapsulate the droplet for other reasons, such as in microfluidic-based DNA analyses. Recently, it has been shown that nonwetting oleophobic surfaces can be forcibly wetted by nonconducting oils using nonuniform electric fields and an interface-localized form of liquid dielectrophoresis (dielectrowetting). Here we show that this effect can be used to create films of oil immersed in a second immiscible fluid of lower permittivity. We predict that the square of the thickness of the film should obey a simple law dependent on the square of the applied voltage and with strength dependent on the ratio of difference in permittivity to the liquid-fluid interfacial tension, Δε/γ(LF). This relationship is experimentally confirmed for 11 liquid-air and liquid-liquid combinations with Δε/γ(LF) having a span of more than two orders of magnitude. We therefore provide fundamental understanding of dielectrowetting for liquid-in-liquid systems and also open up a new method to determine liquid-liquid interfacial tensions. PMID:25519875

  1. Dielectrophoresis-driven spreading of immersed liquid droplets.

    PubMed

    Brown, Carl V; McHale, Glen; Trabi, Christophe L

    2015-01-27

    In recent years electrowetting-on-dielectric (EWOD) has become an effective tool to control partial wetting. EWOD uses the liquid-solid interface as part of a capacitive structure that allows capacitive and interfacial energies to adjust by changes in wetting when the liquid-solid interface is charged due to an applied voltage. An important aspect of EWOD has been its applications in microfluidics in chemistry and biology and in optical devices and displays in physics and engineering. Many of these rely on the use of a liquid droplet immersed in a second liquid due to the need either for neutral buoyancy to overcome gravity and shield against impact shocks or to encapsulate the droplet for other reasons, such as in microfluidic-based DNA analyses. Recently, it has been shown that nonwetting oleophobic surfaces can be forcibly wetted by nonconducting oils using nonuniform electric fields and an interface-localized form of liquid dielectrophoresis (dielectrowetting). Here we show that this effect can be used to create films of oil immersed in a second immiscible fluid of lower permittivity. We predict that the square of the thickness of the film should obey a simple law dependent on the square of the applied voltage and with strength dependent on the ratio of difference in permittivity to the liquid-fluid interfacial tension, Δε/γ(LF). This relationship is experimentally confirmed for 11 liquid-air and liquid-liquid combinations with Δε/γ(LF) having a span of more than two orders of magnitude. We therefore provide fundamental understanding of dielectrowetting for liquid-in-liquid systems and also open up a new method to determine liquid-liquid interfacial tensions.

  2. Liquid Droplet Detachment and Entrainment in Microscale Flows

    NASA Astrophysics Data System (ADS)

    Hidrovo, Carlos

    2005-11-01

    In this talk we will present a first order study of liquid water detachment and entrainment into air flows in hydrophobic microchannels. Silicon based microstructures consisting of 23 mm long U-shaped channels of different geometry were used for this purpose. The structures are treated with a Molecular Vapor Deposition (MVD) process that renders them hydrophobic. Liquid water is injected through a side slot located 2/3 of the way downstream from the air channel inlet. The water entering the air channel beads up into slugs or droplets that grow in size at this injection location until they fill and flood the channel or are carried away by the air flow. The slugs/droplets dimensions at detachment are correlated against superficial gas velocity and proper dimensionless parameters are postulated and examined to compare hydrodynamic forces against surface tension. It is found that slug/droplet detachment is dominated by two main forces: pressure gradient drag, arising from confinement of a viscous flow in the channel, and inertial drag, arising from the stagnation of the air due to obstruction by the slugs/droplets. A detachment regime map is postulated based on the relative importance of these forces under different flow conditions.

  3. Autoignition and burning rates of fuel droplets under microgravity

    SciTech Connect

    Cuoci, A.; Mehl, M.; Buzzi-Ferraris, G.; Faravelli, T.; Manca, D.; Ranzi, E.

    2005-11-01

    This paper presents a mathematical model for the unsteady evaporation, ignition, and combustion of isolated fuel droplets under microgravity. The model consists of a large structured system of differential algebraic equations, where the numerical complexity is due both to the stiff nature of the kinetic mechanism and to the flame structure around the droplet. A very general, detailed kinetic scheme, consisting of {approx}200 species and over 5000 reactions, is used to describe the gas-phase combustion of different fuels. Several comparisons with experimental measurements, carried out under various operating conditions, confirm that the proposed model is a useful tool for characterizing low-temperature and high-temperature ignition delay times. The predicted explosion diagrams of n-alkanes, as well as their ignition delay times, agree with the experimental measurements; the various oxidation regions are closely reproduced, too. In addition to this, recent experimental results, relating to the influence of the initial diameter on droplet burning rates in cold and hot environments, are also presented and discussed. Lastly, an analysis of the extinction diameters for the combustion of n-heptane droplets allows a discussion of the role of radiative heat transfer, as well as further emphasizing the importance of the low-temperature oxidation mechanisms.

  4. Nanoparticle interfacial assembly in liquid crystal droplets

    NASA Astrophysics Data System (ADS)

    Rahimi, Mohammad; Roberts, Tyler; Armas-Perez, Julio; Wang, Xiaoguang; Bukusoglu, Emre; Abbott, Nicholas L.; de Pablo, Juan J.

    2015-03-01

    Controlled assembly of nanoparticles at liquid crystal interfaces could lead to easily manufacturable building blocks for assembly of materials with tunable mechanical, optical, and electronic properties. Past work has examined nanoparticle assembly at planar liquid crystal interfaces. In this work we show that nanoparticle assembly on curved interfaces is drastically different, and arises for conditions under which assembly is too weak to occur on planar interfaces. We also demonstrate that LC-mediated nanoparticle interactions are strong, are remarkably sensitive to surface anchoring, and lead to hexagonal arrangements that do not arise in bulk systems. All these elements form the basis for a highly tunable, predictable, and versatile platform for hierarchical materials assembly. National Science Foundation through the UW MRSEC.

  5. Development of comprehensive numerical schemes for predicting evaporating gas-droplets flow processes of a liquid-fueled combustor. Semiannual report, 15 June 1988-30 November 1988

    SciTech Connect

    Chen, C.P.

    1990-01-01

    An existing Computational Fluid Dynamics code for simulating complex turbulent flows inside a liquid rocket combustion chamber was validated and further developed. The Advanced Rocket Injector/Combustor Code (ARICC) is simplified and validated against benchmark flow situations for laminar and turbulent flows. The numerical method used in ARICC Code is re-examined for incompressible flow calculations. For turbulent flows, both the subgrid and the two equation k-epsilon turbulence models are studied. Cases tested include idealized Burger's equation in complex geometries and boundaries, a laminar pipe flow, a high Reynolds number turbulent flow, and a confined coaxial jet with recirculations. The accuracy of the algorithm is examined by comparing the numerical results with the analytical solutions as well as experimented data with different grid sizes.

  6. Direct numerical simulation of ignition in turbulent n-heptane liquid-fuel spray jets

    SciTech Connect

    Wang, Y.; Rutland, C.J.

    2007-06-15

    Direct numerical simulation was used for fundamental studies of the ignition of turbulent n-heptane liquid-fuel spray jets. A chemistry mechanism with 33 species and 64 reactions was adopted to describe the chemical reactions. The Eulerian method is employed to solve the carrier-gas flow field and the Lagrangian method is used to track the liquid-fuel droplets. Two-way coupling interaction is considered through the exchange of mass, momentum, and energy between the carrier-gas fluid and the liquid-fuel spray. The initial carrier-gas temperature was 1500 K. Six cases were simulated with different droplet radii (from 10 to 30 {mu}m) and two initial velocities (100 and 150 m/s). From the simulations, it was found that evaporative cooling and turbulence mixing play important roles in the ignition of liquid-fuel spray jets. Ignition first occurs at the edges of the jets where the fuel mixture is lean, and the scalar dissipation rate and the vorticity magnitude are very low. For smaller droplets, ignition occurs later than for larger droplets due to increased evaporative cooling. Higher initial droplet velocity enhances turbulence mixing and evaporative cooling. For smaller droplets, higher initial droplet velocity causes the ignition to occur earlier, whereas for larger droplets, higher initial droplet velocity delays the ignition time. (author)

  7. Study of orifice fabrication technologies for the liquid droplet radiator

    NASA Technical Reports Server (NTRS)

    Wallace, David B.; Hayes, Donald J.; Bush, J. Michael

    1991-01-01

    Eleven orifice fabrication technologies potentially applicable for a liquid droplet radiator are discussed. The evaluation is focused on technologies capable of yielding 25-150 microns diameter orifices with trajectory accuracies below 5 milliradians, ultimately in arrays of up to 4000 orifices. An initial analytical screening considering factors such as trajectory accuracy, manufacturability, and hydrodynamics of orifice flow is presented. Based on this screening, four technologies were selected for experimental evaluation. A jet straightness system used to test 50-orifice arrays made by electro-discharge machining (EDM), Fotoceram, and mechanical drilling is discussed. Measurements on orifice diameter control and jet trajectory accuracy are presented and discussed. Trajectory standard deviations are in the 4.6-10.0 milliradian range. Electroforming and EDM appear to have the greatest potential for Liquid Droplet Radiator applications. The direction of a future development effort is discussed.

  8. Droplet impact on deep liquid pools: Rayleigh jet to formation of secondary droplets

    NASA Astrophysics Data System (ADS)

    Castillo-Orozco, Eduardo; Davanlou, Ashkan; Choudhury, Pretam K.; Kumar, Ranganathan

    2015-11-01

    The impact of droplets on a deep pool has applications in cleaning up oil spills, spray cooling, painting, inkjet printing, and forensic analysis, relying on the changes in properties such as viscosity, interfacial tension, and density. Despite the exhaustive research on different aspects of droplet impact, it is not clear how liquid properties can affect the instabilities leading to Rayleigh jet breakup and number of daughter drops formed after its pinch-off. In this article, through systematic experiments we investigate the droplet impact phenomena by varying viscosity and surface tension of liquids as well as impact speeds. Further, using numerical simulations, we show that Rayleigh-Plateau instability is influenced by these parameters, and capillary time scale is the appropriate scale to normalize the breakup time. Based on Ohnesorge number (Oh) and impact Weber number (We), a regime map for no breakup, Rayleigh jet breakup, and crown splash is suggested. Interestingly, crown splash is observed to occur at all Ohnesorge numbers; however, at high Oh, a large portion of kinetic energy is dissipated, and thus the Rayleigh jet is suppressed regardless of high impact velocity. The normalized required time for the Rayleigh jet to reach its peak varies linearly with the critical height of the jet.

  9. Droplet impact on deep liquid pools: Rayleigh jet to formation of secondary droplets.

    PubMed

    Castillo-Orozco, Eduardo; Davanlou, Ashkan; Choudhury, Pretam K; Kumar, Ranganathan

    2015-11-01

    The impact of droplets on a deep pool has applications in cleaning up oil spills, spray cooling, painting, inkjet printing, and forensic analysis, relying on the changes in properties such as viscosity, interfacial tension, and density. Despite the exhaustive research on different aspects of droplet impact, it is not clear how liquid properties can affect the instabilities leading to Rayleigh jet breakup and number of daughter drops formed after its pinch-off. In this article, through systematic experiments we investigate the droplet impact phenomena by varying viscosity and surface tension of liquids as well as impact speeds. Further, using numerical simulations, we show that Rayleigh-Plateau instability is influenced by these parameters, and capillary time scale is the appropriate scale to normalize the breakup time. Based on Ohnesorge number (Oh) and impact Weber number (We), a regime map for no breakup, Rayleigh jet breakup, and crown splash is suggested. Interestingly, crown splash is observed to occur at all Ohnesorge numbers; however, at high Oh, a large portion of kinetic energy is dissipated, and thus the Rayleigh jet is suppressed regardless of high impact velocity. The normalized required time for the Rayleigh jet to reach its peak varies linearly with the critical height of the jet. PMID:26651794

  10. Oscillating Droplets and Incompressible Liquids: Slow-Motion Visualization of Experiments with Fluids

    ERIC Educational Resources Information Center

    Vollmer, Michael; Mollmann, Klaus-Peter

    2012-01-01

    We present fascinating simple demonstration experiments recorded with high-speed cameras in the field of fluid dynamics. Examples include oscillations of falling droplets, effects happening upon impact of a liquid droplet into a liquid, the disintegration of extremely large droplets in free fall and the consequences of incompressibility. (Contains…

  11. The Study of a Liquid Droplet Falling Through Two Immiscible Layers of Liquids

    NASA Astrophysics Data System (ADS)

    Mesa, Bianca

    2013-11-01

    In an exploratory experiment, we noticed the unusual behaviors of liquid droplets falling through layers of oil and water. A rectangular container was filled with an aqueous solution and a layer of oil. A dropper was used to control the size of the droplet. Water was mixed with Bromothymol Blue dye, a chemical indicator, to visualize the flow processes. Surface tension and the buoyancy of the oil layer between the liquid droplet and the water below caused the liquid droplet to be stopped at the interface. Over time, the support weakened and the droplet would fall quickly through the water. The first of two cases was a salt water solution with NaOH, and the second consisted of balsamic vinegar and NaOH. Once the salt water droplet touched the aqueous solution, it collapsed, sank and spread rapidly at the interface. The sinking motion dragged the spreading fluid back to its center and then down. For the second case, a trace amount of the droplet spread rapidly at the interface while the main portion of the droplet sank and then spontaneously exploded. The difference in behavior is mainly due to the surface tension of the droplet in water. The underlying mechanisms of the droplet's flow instability are from the effects of diffusion weakening the surface tension. Bianca Mesa is an undergraduate student in the Ocean and Mechanical Engineering Department at Florida Atlantic University. She is pursuing a B.S. degree in Ocean Engineering. In addition to her academic interests, she is also an avid sailor.

  12. The effect of pressure oscillations on fuel droplet ignition

    NASA Astrophysics Data System (ADS)

    Eigenbrod, Christian; Klinkov, Konstantin; Fachini, Fernando F.

    Combustion-driven instabilities have an important influence on the performance and noise char-acteristics of gas turbines. Thermo-acoustic oscillations can increase not only emissions of noise or pollutants such as unburnt hydrocarbons or nitric oxides, but can also lead to very high levels of pressure pulsations, resulting in structural damage of the machine. Identified mechanisms capable of driving combustion instabilities include complex flow and flame interactions: fuel feed line -acoustic coupling, equivalence-ratio oscillations, oscillatory vaporization and mix-ing, oscillatory flame-area variation, vortex shedding. In order to clarify different aspects of acoustics -combustion interference it is necessary to study the simplified models. At ZARM, Bremen the effect of acoustic oscillation on single droplet ignition was studied experimentally and numerically. The experimental facility allows to investigate the ignition of a single droplet under spherical conditions (absence of natural convection) and variable pressure and temperature of the ambient gas. The suspended fuel droplet with initial diameter of 0.7 mm is placed in a furnace, two opposite walls of which are motor-driven pistons. The scale of the oscillation of gas parameters in the furnace corresponds to that in real gas-turbines under condition of a thermo-acoustic resonance. In the present work parameters of the ignition of a single n-heptane droplet under mean pressure (p0) up to 5 bar and temperature 700 K was examined. The computational model is 1-dimensional and includes processes of vaporization, multi-component diffusion and extended chemical reactions including the low-temperature branch. The model was firstly validated through the single droplet experiments achieving good agreement. Then the physical parameters were varied in order to match conditions of real gas-turbines. In this case droplet diameter was about 0.04-0.1 mm, initial pressure of the gas up to 20 bar and temperature up to 700 K

  13. Pulsating-gliding transition in the dynamics of levitating liquid nitorgen droplets.

    SciTech Connect

    Snezhko, A.; Jacob, E. B.; Aranson, I. S.; Materials Science Division; Tel-Aviv Univ.

    2008-04-21

    Hot surfaces can cause levitation of small liquid droplets if the temperature is kept above the Leidenfrost point (220 C for water) due to the pressure formed because of rapid evaporation. Here, we demonstrate a new class of pulsating-gliding dynamic transitions in a special setting of the Leidenfrost effect at room temperatures and above a viscous fluid for droplets of liquid nitrogen. A whole range of highly dynamic patterns unfolds when droplets of liquid nitrogen are poured on the surface of another, more viscous liquid at room temperature. We also discovered that the levitating droplets induce vortex motion in the supporting viscous liquid. Depending on the viscosity of the supporting liquid, the nitrogen droplets either adopt an oscillating (pulsating) star-like shape with different azimuthal symmetries (from 2-9 petals) or glide on the surface with random trajectories. Thus, by varying the viscosity of the supporting liquid, we achieve controlled morphology and dynamics of Leidenfrost droplets.

  14. Kinetics of diffusional droplet growth in a liquid/liquid two-phase system

    NASA Technical Reports Server (NTRS)

    Glickman, M. E.; Fradkov, V. E.

    1995-01-01

    A new powerful experimental technique based on holographic observations, developed at the NASA Marshall Space Flight Center, now permits observation of small liquid droplets coarsening. This technique was developed and used for mixed-dimensional coarsening studies. Experiments were conducted on an isopycnic two-phase alloy of succinonitrile and water, annealed isothermally over a four-month period. The succinonitrile-rich droplets precipitate from a water-rich liquid matrix having a density very close to that of the droplets. The matrix and droplets, however, have different optical indices. The results of these experiments, along with the results of computer simulation based on the quasi-static diffusion approximation developed at Rensselaer are reported. These results were published recently. Copies of these papers are attached to this report.

  15. Transient direct-contact condensation on liquid droplets

    SciTech Connect

    Pasamehmetoglu, K.O.; Nelson, R.A.

    1987-01-01

    In this paper, direct-contact condensation on subcooled liquid droplets is studied in two parts. In the first part, simple design correlations for the condensation in a steady environment are developed based upon a conduction model. These correlations include the convective heat-transfer coefficient, condensation rate, total condensation, and the droplet-thermalization time. In the second part of the paper, the effect of a time-dependent saturation temperature on the condensation process is investigated. A rapid decrease in saturation temperature is typical of condensation environments in which the steam-supply rate is limited and condensation-induced depressurization becomes important. Design correlations are developed for condensation in an environment in which the saturation temperature decreases linearly with time. These correlations are graphically compared to the design correlations of the first part through a quasi-steady approach. The error associated with this approach is quantified as a function of the rate of change of the saturation temperature.

  16. Transient direct-contact condensation on liquid droplets

    NASA Astrophysics Data System (ADS)

    Pasamehmetoglu, K. O.; Nelson, R. A.

    1987-06-01

    In this paper, direct-contact condensation on subcooled liquid droplets is studied in two parts. In the first part, simple design correlations for the condensation in a steady environment are developed based upon a conduction model. These correlations include the convective heat-transfer coefficient, condensation rate, total condensation, and the droplet-thermalization time. In the second part of the paper, the effect of a time-dependent saturation temperature on the condensation process is investigated. A rapid decrease in saturation temperature is typical of condensation environments in which the steam-supply rate is limited and condensation-induced depressurization becomes important. Design correlations are developed for condensation in an environment in which the saturation temperature decreases linearly with time. These correlations are graphically compared to the design correlations of the first part through a quasi-steady approach. The error associated with this approach is quantified as a function of the rate of change of the saturation temperature.

  17. An Integrated Liquid Cooling System Based on Galinstan Liquid Metal Droplets.

    PubMed

    Zhu, Jiu Yang; Tang, Shi-Yang; Khoshmanesh, Khashayar; Ghorbani, Kamran

    2016-01-27

    The continued miniaturization of electronic components demands integrated liquid cooling systems with minimized external connections and fabrication costs that can be implanted very close to localized hot spots. This might be challenging for existing liquid cooling systems because most of them rely on external pumps, connecting tubes, and microfabricated heat sinks. Here, we demonstrate an integrated liquid cooling system by utilizing a small droplet of liquid metal Galinstan, which is placed over the hot spot. Energizing the liquid metal droplet with a square wave signal creates a surface tension gradient across the droplet, which induces Marangoni flow over the surface of droplet. This produces a high flow rate of coolant medium through the cooling channel, enabling a "soft" pump. At the same time, the high thermal conductivity of liquid metal extends the heat transfer surface and facilitates the dissipation of heat, enabling a "soft" heat sink. This facilitates the rapid cooling of localized hot spots, as demonstrated in our experiments. Our technology facilitates customized liquid cooling systems with simple fabrication and assembling processes, with no moving parts that can achieve high flow rates with low power consumption. PMID:26716607

  18. An Integrated Liquid Cooling System Based on Galinstan Liquid Metal Droplets.

    PubMed

    Zhu, Jiu Yang; Tang, Shi-Yang; Khoshmanesh, Khashayar; Ghorbani, Kamran

    2016-01-27

    The continued miniaturization of electronic components demands integrated liquid cooling systems with minimized external connections and fabrication costs that can be implanted very close to localized hot spots. This might be challenging for existing liquid cooling systems because most of them rely on external pumps, connecting tubes, and microfabricated heat sinks. Here, we demonstrate an integrated liquid cooling system by utilizing a small droplet of liquid metal Galinstan, which is placed over the hot spot. Energizing the liquid metal droplet with a square wave signal creates a surface tension gradient across the droplet, which induces Marangoni flow over the surface of droplet. This produces a high flow rate of coolant medium through the cooling channel, enabling a "soft" pump. At the same time, the high thermal conductivity of liquid metal extends the heat transfer surface and facilitates the dissipation of heat, enabling a "soft" heat sink. This facilitates the rapid cooling of localized hot spots, as demonstrated in our experiments. Our technology facilitates customized liquid cooling systems with simple fabrication and assembling processes, with no moving parts that can achieve high flow rates with low power consumption.

  19. Simulation of water vapor condensation on LOX droplet surface using liquid nitrogen

    NASA Technical Reports Server (NTRS)

    Powell, Eugene A.

    1988-01-01

    The formation of ice or water layers on liquid oxygen (LOX) droplets in the Space Shuttle Main Engine (SSME) environment was investigated. Formulation of such ice/water layers is indicated by phase-equilibrium considerations under conditions of high partial pressure of water vapor (steam) and low LOX droplet temperature prevailing in the SSME preburner or main chamber. An experimental investigation was begun using liquid nitrogen as a LOX simulant. A monodisperse liquid nitrogen droplet generator was developed which uses an acoustic driver to force the stream of liquid emerging from a capillary tube to break up into a stream of regularly space uniformly sized spherical droplets. The atmospheric pressure liquid nitrogen in the droplet generator reservoir was cooled below its boiling point to prevent two phase flow from occurring in the capillary tube. An existing steam chamber was modified for injection of liquid nitrogen droplets into atmospheric pressure superheated steam. The droplets were imaged using a stroboscopic video system and a laser shadowgraphy system. Several tests were conducted in which liquid nitrogen droplets were injected into the steam chamber. Under conditions of periodic droplet formation, images of 600 micron diameter liquid nitrogen droplets were obtained with the stroboscopic video systems.

  20. Implementation of droplet-membrane-droplet liquid-phase microextraction under stagnant conditions for lab-on-a-chip applications.

    PubMed

    Sikanen, Tiina; Pedersen-Bjergaard, Stig; Jensen, Henrik; Kostiainen, Risto; Rasmussen, Knut Einar; Kotiaho, Tapio

    2010-01-25

    In the current work, droplet-membrane-droplet liquid-phase microextraction (LPME) under totally stagnant conditions was presented for the first time. Subsequently, implementation of this concept on a microchip was demonstrated as a miniaturized, on-line sample preparation method. The performance level of the lab-on-a-chip system with integrated microextraction, capillary electrophoresis (CE) and laser-induced fluorescence (LIF) detection in a single miniaturized device was preliminarily investigated and characterized. Extractions under stagnant conditions were performed from 3.5 to 15 microL sample droplets, through a supported liquid membrane (SLM) sustained in the pores of a small piece of a flat polypropylene membrane, and into 3.5-15 microL of acceptor droplet. The basic model analytes pethidine, nortriptyline, methadone, haloperidol, and loperamide were extracted from alkaline sample droplets (pH 12), through 1-octanol as SLM, and into acidified acceptor droplets (pH 2) with recoveries ranging between 13 and 66% after 5 min of operation. For the acidic model analytes Bodipy FL C(5) and Oregon Green 488, the pH conditions were reversed, utilizing an acidic sample droplet and an alkaline acceptor droplet, and 1-octanol as SLM. As a result, recoveries for Bodipy FL C(5) and Oregon Green 488 from human urine were 15 and 25%, respectively.

  1. Effects of fuel properties on the burning characteristics of collision-merged alkane/water droplets

    SciTech Connect

    Wang, C.H.; Pan, K.L.; Huang, W.C.; Wen, H.C.; Yang, J.Y.; Law, C.K.

    2008-04-15

    The combustion characteristics of freely falling droplets, individually generated by the merging of colliding alkane and water droplets, were experimentally investigated. The outcome of the collision droplets was first studied and then the subsequent burning processes such as the flame appearance, ignition and burning behaviors were recorded, through either visual observation or microphotography with the aid of stroboscopic lighting. If the merged droplets were exhibited in an insertive manner, while the water droplet inserted into the alkane droplet, these yield the burning behaviors prior to the end of flame were very much similar to that of pure alkane. The burning was ended with droplet extinction for lower-C alkane, and with either droplet ''flash vaporization'' or extinction for hexadecane. And if the merged droplets were in adhesive manner, for hexadecane with large water content, they either could not be ignited for the large merged droplets, or be ignited with a much prolonged ignition delay, followed by a soot-reducing flame and an ending of droplet extinction for the small merged droplets. ''Homogeneous'' explosion was not observed in any of the tests, and ''heterogeneous'' explosion, induced by trapped air bubbles, occasionally occurred for merged droplets with C-atom in alkane is higher than dodecane. And the sudden disappearance of droplet definitely decreased the burning time and thus enhanced the burning intensity. Besides, the fuel mass consumption rates were increased, even in the cases that having droplet extinction, because of the enlargement of the surface area due to the stuffing of water droplet. (author)

  2. Ecodesign of Liquid Fuel Tanks

    NASA Astrophysics Data System (ADS)

    Gicevska, Jana; Bazbauers, Gatis; Repele, Mara

    2011-01-01

    The subject of the study is a 10 litre liquid fuel tank made of metal and used for fuel storage and transportation. The study dealt with separate life cycle stages of this product, compared environmental impacts of similar fuel tanks made of metal and plastic, as well as analysed the product's end-of-life cycle stage, studying the waste treatment and disposal scenarios. The aim of this study was to find opportunities for improvement and to develop proposals for the ecodesign of 10 litre liquid fuel tank.

  3. Partial Extinction and the Rayleigh Index in Acoustically Driven Fuel Droplet Combustion

    NASA Astrophysics Data System (ADS)

    Valentini, Dario; Tran, Phuoc Hai; Lopez, Brett; Ekmekji, Ari; Smith, Owen; Karagozian, Ann

    2014-11-01

    This experimental study examines burning liquid fuel droplets exposed to standing acoustic waves created within an atmospheric pressure waveguide. Building on prior studies which study relatively low-level excitation conditions in which the droplet is situated in the vicinity of a pressure node (PN), the present experiments focus on higher amplitude excitation which can lead to periodic flame extinction. Phase-locked OH* chemiluminescence imaging reveals temporal oscillations in flame standoff distance from the droplet as well as chemiluminescent intensity in response to the applied acoustic perturbations. Temporal variation in the chemiluminescent intensity as well as pressure in the vicinity of the burning droplet enable quantification of combustion-acoustic coupling via the Rayleigh index. While the sign of the Rayleigh index is consistent with oscillatory combustion during low-level acoustic excitation, when periodic partial extinction occurs at higher amplitude excitation, the Rayleigh index is insufficient to fully represent such coupling. Alternative metrics and methods are explored to enable a more robust study under such conditions. Supported by the University of Pisa and the UC CARE and MSD Scholars programs.

  4. Study on the ignition of a fuel droplet in high temperature stagnant gas

    SciTech Connect

    Yoshizawa, Y.; Tomita, M.; Kawada, H.

    1981-07-01

    This study aimed to clarify the effects of the fuel vapor, which had evaporated in advance and formed combustible mixture around the condensed phase, on the ignition of a fuel droplet under the gas dynamic compression. A soap bubble was utilized to make a heterogeneously distributed fuel vapor pocket in oxidizer gas which offered a model of the vapor cloud around the fuel droplet. Induction periods for the onset of strong emission were measured for fuel droplets, and the models and their ignition processes were examined precisely by means of the interferometric measurement of the fuel concentration field.

  5. Controlling the Localization of Liquid Droplets in Polymer Matrices by Evaporative Lithography.

    PubMed

    Zhao, Huaixia; Xu, Jiajia; Jing, Guangyin; Prieto-López, Lizbeth Ofelia; Deng, Xu; Cui, Jiaxi

    2016-08-26

    Localized inclusions of liquids provide solid materials with many functions, such as self-healing, secretion, and tunable mechanical properties, in a spatially controlled mode. However, a strategy to control the distribution of liquid droplets in solid matrices directly obtained from a homogeneous solution has not been reported thus far. Herein, we describe an approach to selectively localize liquid droplets in a supramolecular gel directly obtained from its solution by using evaporative lithography. In this process, the formation of droplet-embedded domains occurs in regions of free evaporation where the non-volatile liquid is concentrated and undergoes a phase separation to create liquid droplets prior to gelation, while a homogeneous gel matrix is formed in the regions of hindered evaporation. The different regions of a coating with droplet embedment patterns display different secretion abilities, enabling the control of the directional movement of water droplets. PMID:27460600

  6. Effect of droplet shape on ring stains from dried liquid

    NASA Astrophysics Data System (ADS)

    Santiago, Melvin; Brown, Katherine; Mathur, Harsh

    A landmark experimental paper on coffee stains by Deegan et al included a simple theoretical analysis of circular droplets. The analysis was based on a model informally called the Maxwell House equations. It describes the evolving height profile of the droplet, the evaporation of the solvent and the outflow of solute to the rim of the droplet. Since typical droplets are not circles, here we extend the analysis to more general shapes. We find that for thin droplets the height profile may be determined by solving Poisson's equation in a domain corresponding to the footprint of the droplet. Evaporation is treated in a simple approximation via an electrostatic analogy and is dominated by the sharp edges of the droplet. Assuming zero vorticity allows us to analyze the solvent flow in droplets of arbitrary shape. We compare circular droplets to other shapes including long linear droplets, ring shaped droplets and droplets with an elliptical footprint

  7. Liquid crystal droplet array for non-contact electro-optic inspections

    NASA Astrophysics Data System (ADS)

    Ren, Hongwen; Xianyu, Haiqing; Wu, Shin-Tson

    2010-09-01

    We report a high density liquid crystal (LC) droplet array for non-contact inspection. The incident light is modulated by changing the shape of each droplet using a dielectric force even though the electrode and droplet array are separated by a fairly large air gap. The reshaped LC droplets cause colour change which is easily inspected by the human eye. In a sample with 30 µm thick polymer cavity and 130 µm air gap, LC droplet surface reshaping is clearly observed as the applied voltage exceeds 40 Vrms. Potential application of such a LC droplet array for inspecting the defected thin-film-transistor pixels is emphasized.

  8. The effect of initial diameter in sperically symmetric droplet combustion of sooting fuels

    NASA Technical Reports Server (NTRS)

    Jackson, G. S.; Avedisian, C. T.

    1994-01-01

    The effect of initial droplet diameter on the burning rate of sooting fuels - n-heptane and 1-chloro-octane - was examined experimentally at low gravity. A 1.2s drop tower provided a low gravity environment to minimize buoyancy and achieve spherically symmetric flames for stationary droplets. Free-floating and fiber-supported droplets were burned, and both techniques gave matching results for droplets of similar initial diameter. Burning rate constants for both fuels were measured for a large number of droplets ranging from 0.4 to 1.1mm in initial diameter.

  9. Experiments on the effect of initial diameter in spherically symmetric droplet combustion of sooting fuels

    NASA Technical Reports Server (NTRS)

    Jackson, G. S.; Avedisian, C. T.

    1993-01-01

    The effect of initial droplet diameter on the burning rate of sooting fuels (n-heptane and 1-chloro-octane) is studied experimentally at low gravity. A 1.2 s drop tower provided a low gravity environment to minimize buoyancy and achieve spherically symmetric flames for stationary droplets. Free-floating and fiber supported droplets were burned, and both methods gave matching results for droplets of similar initial diameter.

  10. Liquid plasticine: controlled deformation and recovery of droplets with interfacial nanoparticle jamming.

    PubMed

    Li, Xiaoguang; Xue, Yahui; Lv, Pengyu; Lin, Hao; Du, Feng; Hu, Yueyun; Shen, Jun; Duan, Huiling

    2016-02-14

    Air-exposed droplet systems are widely applied in material preparation and experimental design. Recently, a droplet system with unusual properties featured by a liquid-like appearance and solid-like deformability was produced. However, it was then just an interesting and perplexing phenomenon in the absence of basic understandings and clear perspectives for applications. Here we reveal that stable droplet deformation is attributed to monolayer nanoparticle jamming at the water/vapor interface, and that the normal shape can be recovered by jamming relieving. The degree of jamming affects the droplet shape and transparency and can be tuned by the squeezing force and droplet volume. Using these properties and control methods, we develop the deformed droplet into "liquid plasticine" with predesigned shapes, super-high transparency, and arbitrarily large volume. We demonstrate that liquid plasticine could be used as liquid lenses, channel-like containers, and miniature reactors. PMID:26742837

  11. Influence of droplet size, pH and ionic strength on endotoxin-triggered ordering transitions in liquid crystalline droplets

    PubMed Central

    Miller, Daniel S.; Abbott, Nicholas L.

    2012-01-01

    We report an investigation of ordering transitions that are induced in water-dispersed, micrometer-sized droplets of a thermotropic liquid crystal (LC) by the bacterial lipopolysaccharide endotoxin. We reveal that the ordering transitions induced by endotoxin – from a bipolar state of the droplets to a radial state – are strongly dependent on the size of the LC droplets. Specifically, as the diameters of the LC droplets increase from 2 μm to above 10 μm (in phosphate buffered saline with an ionic strength of 90 mM and a pH of 7.2), we measured the percentage of droplets exhibiting a radial configuration in the presence of 100 pg/mL endotoxin to decrease from 98 ± 1 % to 3 ± 2 %. In addition, we measured a decrease in either the ionic strength or pH of the aqueous phase to reduce the percentage of droplets exhibiting a radial configuration in the presence of endotoxin. These results, when interpreted within the context of a simple thermodynamic model that incorporates the contributions of elasticity and surface anchoring to the free energies of the LC droplets, lead us to conclude that (i) the elastic constant K24 plays a central role in determining the size-dependent response of the LC droplets to endotoxin, and (ii) endotoxin-triggered ordering transitions occur only under solution conditions (pH, ionic strength) where the combined contributions of elasticity and surface anchoring to the free energies of the bipolar and radial configurations of the LC droplets are similar in magnitude. Our analysis also suggests that the presence of endotoxin perturbs the free energies of the LC droplets by ~10−17 J/droplet, which is comparable to the standard free energy of self-association of ~103 endotoxin molecules. These results, when combined with prior reports of localization of endotoxin at the center of LC droplets, are consistent with the hypothesis that self-assembly of endotoxin within micrometer-sized LC droplets provides the driving force for the ordering

  12. Combined thermocapillary and buoyancy-driven convection within short-duration pulse-heated liquid droplets

    SciTech Connect

    Shen, F.; Khodadadi, J.M.

    1999-12-01

    Containerless processing of advanced materials and thermophysical property determination techniques for high-temperature materials almost exclusively manipulate spherical droplets. Spherical droplets are also observed in other industrial applications and naturally occurring phenomena, such as spray forming, fuel droplet vaporization, thermal storage technology, powder metallurgy, and environmental transport. In addition to the heat diffusion mode of thermal transport, the possible mechanisms of convection that may be encountered within droplets are surface-tension-driven and buoyancy-driven convection. Here, buoyancy-driven convection and its interaction with thermocapillary flow within short-duration-heated liquid droplets was studied computationally. A parametric study was conducted to investigate the effect of the Grashof number Gr and the surface-tension Reynolds number Re for fluids with different Prandtl numbers Pr having both negative and positive surface-tension temperature coefficients ({partial{underscore}derivative}{sigma}/{partial{underscore}derivative}T). Both the additive and impeding effects of buoyancy-driven convection on the thermocapillary flow was observed. The numerical analysis indicated that the buoyancy-driven convection has a weak effect on low-Pr fluids during the short-pulse-heating condition. For mid-Pr fluids the buoyancy effect is more prominent. In monitoring the history of the surface temperature rise, it was found that the buoyancy-driven convection has a weak effect for low-Pr fluids at the side and bottom observation points, whereas buoyancy-driven convection has substantial influence at the bottom observation point for mid-Pr fluids with a positive surface-tension temperature coefficient. It was concluded that the presence of additive or impeding modes depends not only on the sign of the surface-tension temperature coefficient of fluids as proposed by other researchers, but also on Pr, geometry, and boundary conditions. The

  13. Droplet turbulence interactions under subcritical and supercritical conditions

    NASA Astrophysics Data System (ADS)

    Coy, E. B.; Greenfield, S. C.; Ondas, M. S.; Song, Y.-H.; Spegar, T. D.; Santavicca, D. A.

    1993-11-01

    The goal of this research is to experimentally characterize the behavior of droplets in vaporizing liquid sprays under conditions typical of those encountered in high pressure combustion systems such as liquid fueled rocket engines. Of particular interest are measurements of droplet drag, droplet heating, droplet vaporization, droplet distortion, and secondary droplet breakup, under both subcritical and supercritical conditions. The paper presents a brief description of the specific accomplishments which have been made over the past year.

  14. Droplet turbulence interactions under subcritical and supercritical conditions

    NASA Technical Reports Server (NTRS)

    Coy, E. B.; Greenfield, S. C.; Ondas, M. S.; Song, Y.-H.; Spegar, T. D.; Santavicca, D. A.

    1993-01-01

    The goal of this research is to experimentally characterize the behavior of droplets in vaporizing liquid sprays under conditions typical of those encountered in high pressure combustion systems such as liquid fueled rocket engines. Of particular interest are measurements of droplet drag, droplet heating, droplet vaporization, droplet distortion, and secondary droplet breakup, under both subcritical and supercritical conditions. The paper presents a brief description of the specific accomplishments which have been made over the past year.

  15. Evaporation of liquid droplets from a surface of anodized aluminum

    NASA Astrophysics Data System (ADS)

    Kuznetsov, G. V.; Feoktistov, D. V.; Orlova, E. G.

    2016-01-01

    The results of study of evaporation of water droplets and NaCl salt solution from a solid substrate made of anodized aluminum are presented in this paper. The experiment provides the parameters describing the droplet profile: contact spot diameter, contact angle, and droplet height. The specific rate of evaporation was calculated from the experimental data. The water droplets or brine droplets with concentration up to 9.1 % demonstrate evaporation with the pinning mode for the contact line. When the salt concentration in the brine is taken up to 16.7 %, the droplet spreading mode was observed. Two stages of droplet evaporation are distinguished as a function of phase transition rate.

  16. Single fiber optical trapping of a liquid droplet and its application in microresonator

    NASA Astrophysics Data System (ADS)

    Liu, Zhihai; Chen, Yunhao; Zhao, Li; Zhang, Yu; Wei, Yong; Zhu, Zongda; Yang, Jun; Yuan, Libo

    2016-12-01

    We propose and demonstrate an optical trapping of a liquid droplet and its application based on an annular core microstructured optical fiber. We grind and polish the annular core fiber tip to be a special frustum cone shape to make sure the optical force large enough to trap the liquid droplet non-intrusively. The axial and transverse optical trapping forces are simulated. In addition, we investigate the whispering gallery modes resonance characteristic of the trapped liquid droplet as the example of applications. The whispering gallery modes spectrum is sensitive to the size of the micro liquid droplet. Due to the simple construction and flexible manipulation, the fiber-based optical trapping technology for micro liquid droplets trapping, manipulating, and controlling has great application penitential in many fields, such as physics, biology, and interdisciplinary studies.

  17. EXPERIMENTAL LIQUID METAL FUEL REACTOR

    DOEpatents

    Happell, J.J.; Thomas, G.R.; Denise, R.P.; Bunts, J.L. Jr.

    1962-01-23

    A liquid metal fuel nuclear fission reactor is designed in which the fissionable material is dissolved or suspended in a liquid metal moderator and coolant. The liquid suspension flows into a chamber in which a critical amount of fissionable material is obtained. The fluid leaves the chamber and the heat of fission is extracted for power or other utilization. The improvement is in the support arrangement for a segrnented graphite core to permit dif ferential thermal expansion, effective sealing between main and blanket liquid metal flows, and avoidance of excessive stress development in the graphite segments. (AEC)

  18. Stationary shapes of confined rotating magnetic liquid droplets.

    PubMed

    Lira, Sérgio A; Miranda, José A; Oliveira, Rafael M

    2010-09-01

    We study the family of steady shapes which arise when a magnetic liquid droplet is confined in a rotating Hele-Shaw cell and subjected to an azimuthal magnetic field. Two different scenarios are considered: first, the magnetic fluid is assumed to be a Newtonian ferrofluid, and then it is taken as a viscoelastic magnetorheological fluid. The influence of the distinct material properties of the fluids on the ultimate morphology of the emerging stationary patterns is investigated by using a vortex-sheet formalism. Some of these exact steady structures are similar to the advanced time patterns obtained by existing time-evolving numerical simulations of the problem. A weakly nonlinear approach is employed to examine this fact and to gain analytical insight about relevant aspects related to the stability of such exact stationary solutions. PMID:21230182

  19. Liquid trampolines: droplets and spheres bouncing off soap films

    NASA Astrophysics Data System (ADS)

    Courbin, Laurent; Dubail, Jerome; Crotiere, Suzie; Quere, David

    2005-11-01

    We report on the impact of rigid spheres and liquid droplets on soap films. These systems exhibit a rich variety of dynamics including bouncing and adhesion. In the case of drop impact, at low speeds the drops bounce, while for intermediate speeds the drops can pass through the film without the film breaking. The bouncing can be analyzed using mechanical models. In the case of the impact of rigid spheres, by tuning the physical property of the surface of the impacting sphere, which may or may not be surrounded by a skin of oil, we experimentally observe two distinct regimes: the solid sphere can bounce off of the fluid film or get entrapped. In all cases the film can be considered an absorber of kinetic energy. Finally, the possibility of tuning the bounce of an object will be presented.

  20. Rebound of continuous droplet streams from an immiscible liquid pool

    NASA Astrophysics Data System (ADS)

    Doak, William J.; Laiacona, Danielle M.; German, Guy K.; Chiarot, Paul R.

    2016-05-01

    We report on the rebound of high velocity continuous water droplet streams from the surface of an immiscible oil pool. The droplets have diameters and velocities of less than 90 μm and 15 m/s, respectively, and were created at frequencies up to 60 kHz. The impact and rebound of continuous droplet streams at this scale and velocity have been largely unexplored. This regime bridges the gap between single drop and jet impacts. The impinging droplets create a divot at the surface of the oil pool that had a common characteristic shape across a wide-range of droplet and oil properties. After impact, the reflected droplets maintain the same uniformity and periodicity of the incoming droplets but have significantly lower velocity and kinetic energy. This was solely attributed to the generation of a flow induced in the viscous oil pool by the impacting droplets. Unlike normally directed impact of millimeter-scale droplets with a solid surface, our results show that an air film does not appear to be maintained beneath the droplets during impact. This suggests direct contact between the droplets and the surface of the oil pool. A ballistic failure limit, correlated with the Weber number, was identified where the rebound was suppressed and the droplets were driven through the oil surface. A secondary failure mode was identified for aperiodic incoming streams. Startup effects and early time dynamics of the rebounding droplet stream were also investigated.

  1. Non-equilibrium diffusion combustion of a fuel droplet

    NASA Astrophysics Data System (ADS)

    Tyurenkova, Veronika V.

    2012-06-01

    A mathematical model for the non-equilibrium combustion of droplets in rocket engines is developed. This model allows to determine the divergence of combustion rate for the equilibrium and non-equilibrium model. Criterion for droplet combustion deviation from equilibrium is introduced. It grows decreasing droplet radius, accommodation coefficient, temperature and decreases on decreasing diffusion coefficient. Also divergence from equilibrium increases on reduction of droplet radius. Droplet burning time essentially increases under non-equilibrium conditions. Comparison of theoretical and experimental data shows that to have adequate solution for small droplets it is necessary to use the non-equilibrium model.

  2. Liquid-propellant droplet vaporization and combustion in high pressure environments

    NASA Technical Reports Server (NTRS)

    Yang, Vigor

    1991-01-01

    In order to correct the deficiencies of existing models for high-pressure droplet vaporization and combustion, a fundamental investigation into this matter is essential. The objective of this research are: (1) to acquire basic understanding of physical and chemical mechanisms involved in the vaporization and combustion of isolated liquid-propellant droplets in both stagnant and forced-convective environments; (2) to establish droplet vaporization and combustion correlations for the study of liquid-propellant spray combustion and two-phase flowfields in rocket motors; and (3) to investigate the dynamic responses of multicomponent droplet vaporization and combustion to ambient flow oscillations.

  3. Aerosol feed direct methanol fuel cell

    NASA Technical Reports Server (NTRS)

    Kindler, Andrew (Inventor); Narayanan, Sekharipuram R. (Inventor); Valdez, Thomas I. (Inventor)

    2002-01-01

    Improvements to fuel cells include introduction of the fuel as an aerosol of liquid fuel droplets suspended in a gas. The particle size of the liquid fuel droplets may be controlled for optimal fuel cell performance by selection of different aerosol generators or by separating droplets based upon size using a particle size conditioner.

  4. Liquid Fuels from Microalgae

    SciTech Connect

    Johnson, D. A.; Sprague, S.

    1987-08-01

    The goal of the DOE/SERI Aquatic Species Program is to develop the technology to produce gasoline and diesel fuels from microalgae. Microalgae can accumulate large quantities of lipids and can thrive in high salinity water, which currently has no other use.

  5. Generation of Monodisperse Liquid Droplets in a Microfluidic Chip Using a High-Speed Gaseous Microflow

    NASA Astrophysics Data System (ADS)

    Tirandazi, Pooyan; Hidrovo, Carlos

    2015-11-01

    Over the last few years, microfluidic systems known as Lab-on-a-Chip (LOC) and micro total analysis systems (μTAS) have been increasingly developed as essential components for numerous biochemical applications. Droplet microfluidics, however, provides a distinctive attribute for delivering and processing discrete as well as ultrasmall volumes of fluid, which make droplet-based systems more beneficial over their continuous-phase counterparts. Droplet generation in its conventional scheme usually incorporates the injection of a liquid (water) into a continuous immiscible liquid (oil) medium. In this study we demonstrate a novel scheme for controlled generation of monodisperse droplets in confined gas-liquid microflows. We experimentally investigate the manipulation of water droplets in flow-focusing configurations using a high inertial air stream. Different flow regimes are observed by varying the gas and liquid flow rates, among which, the ``dripping regime'' where monodisperse droplets are generated is of great importance. The controlled size and generation rate of droplets in this region provide the capability for precise and contaminant-free delivery of microliter to nanoliter volumes of fluid. Furthermore, the high speed droplets generated in this method represent the basis for a new approach based on droplet pair collisions for fast efficient micromixing which provides a significant development in modern LOC and μTAS devices. This project is currently being supported by an NSF CAREER Award grant CBET-1151091.

  6. Experimental Study of the Hydrodynamic Resistance of Liquid Droplets in Polycarbonate Microchannels

    NASA Astrophysics Data System (ADS)

    Almutairi, Zeyad; Ren, Carolyn; Johnson, David

    2014-03-01

    The presence of liquid droplets in a microchannel adds excess hydrodynamic resistance to the flow compared to single phase flow. The hydrodynamic resistance of liquid droplets is a function of fluid properties (viscosity ratios μd/μc, interfacial tension γ), geometrical properties of the droplet and the confining channel (droplet length Ld, microchannel width and height), and flow condition (Ca, Re). This work presents the results of an experimental examination of the transport properties of liquid droplets in a microchannel. Focus was given to the hydrodynamic resistance of droplets with lengths comparable or greater than the channel width (LdWch . Experiments were performed in surface modified polycarbonate microchannels since they will reduce measurement uncertainties associated with channel swelling in soft materials such as PDMS. For the droplets sizes that were examined results confirm the relation between the hydrodynamic resistance of liquid droplets and the Capillary number (Ca). It was also observed that droplet slip (β =ud/uc , avg) is less than 1 in all the experiments performed. Funds for microchannel fabrication from CMC Microsystems, and NSERC - Natural Sciences and Engineering Research Council of Canada.

  7. Fuel Injector With Shear Atomizer

    NASA Technical Reports Server (NTRS)

    Beal, George W.; Mills, Virgil L.; Smith, Durward B., II; Beacom, William F.

    1995-01-01

    Atomizer for injecting liquid fuel into combustion chamber uses impact and swirl to break incoming stream of fuel into small, more combustible droplets. Slanted holes direct flow of liquid fuel to stepped cylindrical wall. Impact on wall atomizes liquid. Air flowing past vanes entrains droplets of liquid in swirling flow. Fuel injected at pressure lower than customarily needed.

  8. Droplet Combustion Experiment (DCE)

    NASA Technical Reports Server (NTRS)

    Haggard, John B., Jr.; Nayagan, Vedha; Dryer, Frederick L.; Williams, Forman A.

    1998-01-01

    The first space-based experiments were performed on the combustion of free, individual liquid fuel droplets in oxidizing atmospheres. The fuel was heptane, with initial droplet diameters ranging about from 1 mm to 4 mm. The atmospheres were mixtures of helium and oxygen, at pressures of 1.00, 0.50 and 0.25 bar, with oxygen mole fractions between 20% and 40%, as well as normal Spacelab cabin air. The temperatures of the atmospheres and of the initial liquid fuel were nominally 300 K. A total of 44 droplets were burned successfully on the two flights, 8 on the shortened STS-83 mission and 36 on STS-94. The results spanned the full range of heptane droplet combustion behavior, from radiative flame extinction at larger droplet diameters in the more dilute atmospheres to diffusive extinction in the less dilute atmospheres, with the droplet disappearing prior to flame extinction at the highest oxygen concentrations. Quasisteady histories of droplet diameters were observed along with unsteady histories of flame diameters. New and detailed information was obtained on burning rates, flame characteristics and soot behavior. The results have motivated new computational and theoretical investigations of droplet combustion, improving knowledge of the chemical kinetics, fluid mechanics and heat and mass transfer processes involved in burning liquid fuels.

  9. Droplet condensation and growth on nanotextured surfaces impregnated with an immiscible liquid

    NASA Astrophysics Data System (ADS)

    Anand, Sushant; Paxson, Adam; Smith, Jonathan; Dhiman, Rajeev; Varanasi, Kripa

    2012-02-01

    For effective dropwise condensation, a surface that sheds droplets easily is desirable due to the enhancement in accompanying heat transfer. Incorporating nano-textures on the surface can enhance the droplet shedding or spreading. We demonstrate that droplet shedding can be further influenced by impregnating the nano-textured surface with a liquid which is immiscible with respect to the droplet. In this study, the dynamics of dropwise condensation on such immiscible liquid impregnated nano-textured surfaces have been investigated in pure quiescent water vapor conditions. Condensation experiments were conducted using an Environmental Scanning Electron Microscope by controlling the chamber water vapor pressure and substrate temperature. We show preferential sites for condensation and different modes under which droplets grow, depending upon the surface chemistry, surface texture, and the impregnating liquid properties. Concurrently, we show an evolution of apparent contact angles during the condensation process on the impregnated surfaces.

  10. Design of Functional Materials based on Liquid Crystalline Droplets

    PubMed Central

    Miller, Daniel S.; Wang, Xiaoguang; Abbott, Nicholas L.

    2014-01-01

    This brief perspective focuses on recent advances in the design of functional soft materials that are based on confinement of low molecular weight liquid crystals (LCs) within micrometer-sized droplets. While the ordering of LCs within micrometer-sized domains has been explored extensively in polymer-dispersed LC materials, recent studies performed with LC domains with precisely defined size and interfacial chemistry have unmasked observations of confinement-induced ordering of LCs that do not follow previously reported theoretical predictions. These new findings, which are enabled in part by advances in the preparation of LCs encapsulated in polymeric shells, are opening up new opportunities for the design of soft responsive materials based on surface-induced ordering transitions. These materials are also providing new insights into the self-assembly of biomolecular and colloidal species at defects formed by LCs confined to micrometer-sized domains. The studies presented in this perspective serve additionally to highlight gaps in knowledge regarding the ordering of LCs in confined systems. PMID:24882944

  11. Burning of a spherical fuel droplet in a uniform subsonic flowfield

    SciTech Connect

    Madooglu, K.; Karagozian, A.R.

    1989-12-31

    An analytical/numerical model is described for the evaporation and burning of a spherical fuel droplet in a subsonic crossflow. The external gaseous flowfield is represented using an approximate compressible potential solution, while the internal flowfield of the droplet is represented by the classical Hill`s spherical vortex. This allows numerical solution for the external boundary layer and diffusion flame characteristics to be made, from which the droplet`s effective drag coefficient, rate of mass loss, size, and flame shape are determined. Comparison with experimental data indicate good agreement, and thus the potential for such simplified models in performing parametric studies.

  12. Thermocapillary Migration of Liquid Droplets Induced by a Unidirectional Thermal Gradient.

    PubMed

    Dai, Qingwen; Khonsari, M M; Shen, Cong; Huang, Wei; Wang, Xiaolei

    2016-08-01

    A liquid droplet placed on a nonuniformly heated solid surface will migrate from a high-temperature region to a low-temperature region. This study reports the development of a theoretical model and experimental investigation on the migration behavior of paraffin oil droplets induced by the unidirectional thermal gradient. Thin-film lubrication theory is employed to determine the migration velocity of droplets, and temperature dependence of viscosity is taken into account. Comparisons between experimental and numerical results are presented. An effective approach for estimating the thermocapillary migration velocity of droplets on lubrication is proposed. PMID:27400229

  13. Finite-difference time-domain analysis of light propagation in cholesteric liquid crystalline droplet array

    NASA Astrophysics Data System (ADS)

    Yamamoto, Kaho; Iwai, Yosuke; Uchida, Yoshiaki; Nishiyama, Norikazu

    2016-08-01

    We numerically analyzed the light propagation in cholesteric liquid crystalline (CLC) droplet array by the finite-difference time-domain (FDTD) method. The FDTD method successfully reproduced the experimental light path observed in the complicated photonic structure of the CLC droplet array more accurately than the analysis of CLC droplets by geometric optics with Bragg condition, and this method help us understand the polarization of the propagating light waves. The FDTD method holds great promise for the design of various photonic devices composed of curved photonic materials like CLC droplets and microcapsules.

  14. Coal-to-Liquid Fuels

    SciTech Connect

    Parker, Graham B.

    2006-01-18

    This book chapter describes a chemical process that is the key for turning coal into liquid fuels. This process, known as the Fischer-Tropsch (FT) process, has the potential for producing hundreds of thousands of barrels per day of hydrocarbon liquids and other byproducts, including electricity. The FT process, which was invented in Germany in the 1920s, is used today in full-scale production plants in South Africa and is planned for use in plants in many other parts of the world, including the United States.

  15. Marangoni Convection in Evaporating Organic Liquid Droplets on a Nonwetting Substrate.

    PubMed

    Chandramohan, Aditya; Dash, Susmita; Weibel, Justin A; Chen, Xuemei; Garimella, Suresh V

    2016-05-17

    We quantitatively characterize the flow field inside organic liquid droplets evaporating on a nonwetting substrate. A mushroom-structured surface yields the desired nonwetting behavior with methanol droplets, while use of a cooled substrate (5-15 °C) slows the rate of evaporation to allow quasi-static particle image velocimetry. Visualization reveals a toroidal vortex within the droplet that is characteristic of surface tension-driven flow; we demonstrate by means of a scaling analysis that this recirculating flow is Marangoni convection. The velocities in the droplet are on the order of 10-45 mm/s. Thus, unlike in the case of evaporation on wetting substrates where Marangoni convection can be ignored for the purpose of estimating the evaporation rate, advection due to the surface tension-driven flow plays a dominant role in the heat transfer within an evaporating droplet on a nonwetting substrate because of the large height-to-radius aspect ratio of the droplet. We formulate a reduced-order model that includes advective transport within the droplet for prediction of organic liquid droplet evaporation on a nonwetting substrate and confirm that the predicted temperature differential across the height of the droplet matches experiments. PMID:27119436

  16. High pressure combustion of liquid fuels. [alcohol and n-paraffin fuels

    NASA Technical Reports Server (NTRS)

    Canada, G. S.

    1974-01-01

    Measurements were made of the burning rates and liquid surface temperatures for a number of alcohol and n-paraffin fuels under natural and forced convection conditions. Porous spheres ranging in size from 0.64-1.9 cm O.D. were emloyed to simulate the fuel droplets. The natural convection cold gas tests considered the combustion in air of methanol, ethanol, propanol-1, n-pentane, n-heptane, and n-decane droplets at pressures up to 78 atmospheres. The pressure levels of the natural convection tests were high enough so that near critical combustion was observed for methanol and ethanol vaporization rates and liquid surface temperature measurements were made of droplets burning in a simulated combustion chamber environment. Ambient oxygen molar concentrations included 13%, 9.5% and pure evaporation. Fuels used in the forced convection atmospheric tests included those listed above for the natural convection tests. The ambient gas temperature ranged from 600 to 1500 K and the Reynolds number varied from 30 to 300. The high pressure forced convection tests employed ethanol and n-heptane as fuels over a pressure range of one to 40 atmospheres. The ambient gas temperature was 1145 K for the two combustion cases and 1255 K for the evaporation case.

  17. A numerical study of thermocapillary migration of a small liquid droplet on a horizontal solid surface

    NASA Astrophysics Data System (ADS)

    Nguyen, Huy-Bich; Chen, Jyh-Chen

    2010-06-01

    In the present study, the transient thermocapillary migration of a small liquid droplet on a horizontal solid surface is numerically investigated. The droplet has a large static contact angle and a high aspect ratio of the maximum height of the droplet to its footprint. The Navier-Stokes and energy equations for both the droplet and surrounding air are solved through the finite element method. The evolution of the isotherms, the flow fields and the contact angle hysteresis are presented. Two asymmetric thermocapillary vortices appear inside the droplet. The variation of the size of the thermocapillary vortex during the migration process causes the speed of the droplet to first increase significantly, and then decrease gradually to approach a constant value. The higher imposed temperature gradient causes the droplet velocity to reach its maximal value earlier and have a higher final speed. If the static contact angle of the droplet is less than (or higher) than 90°, the droplet speed is lower (or higher) since the net thermocapillary momentum in the horizontal direction is diminished (or enhanced) by the presence of capillary force. The present results for the migration velocity and the contact angle hysteresis for a squalane droplet are also in good agreement with the previous experimental results.

  18. Cloud Liquid Water, Mean Droplet Radius and Number Density Measurements Using a Raman Lidar

    NASA Technical Reports Server (NTRS)

    Whiteman, David N.; Melfi, S. Harvey

    1999-01-01

    A new technique for measuring cloud liquid water, mean droplet radius and droplet number density is outlined. The technique is based on simultaneously measuring Raman and Mie scattering from cloud liquid droplets using a Raman lidar. Laboratory experiments on liquid micro-spheres have shown that the intensity of Raman scattering is proportional to the amount of liquid present in the spheres. This fact is used as a constraint on calculated Mie intensity assuming a gamma function particle size distribution. The resulting retrieval technique is shown to give stable solutions with no false minima. It is tested using Raman lidar data where the liquid water signal was seen as an enhancement to the water vapor signal. The general relationship of retrieved average radius and number density is consistent with traditional cloud physics models. Sensitivity to the assumed maximum cloud liquid water amount and the water vapor mixing ratio calibration are tested. Improvements to the technique are suggested.

  19. Cloud liquid water, mean droplet radius, and number density measurements using a Raman lidar

    SciTech Connect

    Whiteman, David N.; Melfi, S. Harvey

    1999-12-27

    A new technique for measuring cloud liquid water, mean droplet radius, and droplet number density is outlined. The technique is based on simultaneously measuring Raman and Mie scattering from cloud liquid droplets using a Raman lidar. Laboratory experiments on liquid microspheres have shown that the intensity of Raman scattering is proportional to the amount of liquid present in the spheres. This fact is used as a constraint on calculated Mie intensity assuming a gamma function particle size distribution. The resulting retrieval technique is shown to give stable solutions with no false minima. It is tested using Raman lidar data where the liquid water signal was seen as an enhancement to the water vapor signal. The general relationship of retrieved average radius and number density is consistent with traditional cloud physics models. Sensitivity to the assumed maximum cloud liquid water amount and the water vapor mixing ratio calibration are tested. Improvements to the technique are suggested. (c) 1999 American Geophysical Union.

  20. Transient Numerical Modeling of the Combustion of Bi-Component Liquid Droplets: Methanol/Water Mixture

    NASA Technical Reports Server (NTRS)

    Marchese, A. J.; Dryer, F. L.

    1994-01-01

    This study shows that liquid mixtures of methanol and water are attractive candidates for microgravity droplet combustion experiments and associated numerical modeling. The gas phase chemistry for these droplet mixtures is conceptually simple, well understood and substantially validated. In addition, the thermodynamic and transport properties of the liquid mixture have also been well characterized. Furthermore, the results obtained in this study predict that the extinction of these droplets may be observable in ground-based drop to tower experiments. Such experiments will be conducted shortly followed by space-based experiments utilizing the NASA FSDC and DCE experiments.

  1. Reduction in the Vapor Pressure in Condensation on Cold Droplets of a Liquid

    NASA Astrophysics Data System (ADS)

    Bochkareva, E. M.; Nemtsev, V. A.; Sorokin, V. V.; Terekhov, V. V.; Terekhov, V. I.

    2016-05-01

    A physicomathematical model of the process of depressurization in a pure saturated and superheated vapor due to the injection of monodisperse cold droplets of a liquid has been developed. A cellular model has been developed that is based on solving the equation of heat conduction in a liquid phase and on the integral method for a gas phase in a spherically symmetric one-dimensional formulation. Numerical investigation has been carried out of the influence of the size and concentration of the droplets and of the initial parameters of the steam on the dynamics of depressurization during the vapor condensation on the droplets.

  2. Reduced Gravity Studies of Soret Transport Effects in Liquid Fuel Combustion

    NASA Technical Reports Server (NTRS)

    Shaw, Benjamin D.

    2004-01-01

    Soret transport, which is mass transport driven by thermal gradients, can be important in practical flames as well as laboratory flames by influencing transport of low molecular weight species (e.g., monatomic and diatomic hydrogen). In addition, gas-phase Soret transport of high molecular weight fuel species that are present in practical liquid fuels (e.g., octane or methanol) can be significant in practical flames (Rosner et al., 2000; Dakhlia et al., 2002) and in high pressure droplet evaporation (Curtis and Farrell, 1992), and it has also been shown that Soret transport effects can be important in determining oxygen diffusion rates in certain classes of microgravity droplet combustion experiments (Aharon and Shaw, 1998). It is thus useful to obtain information on flames under conditions where Soret effects can be clearly observed. This research is concerned with investigating effects of Soret transport on combustion of liquid fuels, in particular liquid fuel droplets. Reduced-gravity is employed to provide an ideal (spherically-symmetrical) experimental model with which to investigate effects of Soret transport on combustion. The research will involve performing reduced-gravity experiments on combustion of liquid fuel droplets in environments where Soret effects significantly influence transport of fuel and oxygen to flame zones. Experiments will also be performed where Soret effects are not expected to be important. Droplets initially in the 0.5 to 1 mm size range will be burned. Data will be obtained on influences of Soret transport on combustion characteristics (e.g., droplet burning rates, droplet lifetimes, gas-phase extinction, and transient flame behaviors) under simplified geometrical conditions that are most amenable to theoretical modeling (i.e., spherical symmetry). The experiments will be compared with existing theoretical models as well as new models that will be developed. Normal gravity experiments will also be performed.

  3. Micro magnetofluidics: droplet manipulation of double emulsions based on paramagnetic ionic liquids.

    PubMed

    Misuk, Viktor; Mai, Andreas; Giannopoulos, Konstantinos; Alobaid, Falah; Epple, Bernd; Loewe, Holger

    2013-12-01

    The ability to control and manipulate discrete fluid droplets by magnetic fields offers new opportunities in microfluidics. A surfactant-free and easy to realize technique for the continuous generation of double emulsion droplets, composed of an organic solvent and a paramagnetic ionic liquid, is applied. The inner phase of the emulsion droplet consists of imidazolium-based ionic liquids with either iron, manganese, nickel or dysprosium containing anions which provide paramagnetic behaviour. The double emulsion droplets are dispersed in a continuous phase of FC-40. All substances - the organic phase, the paramagnetic ionic liquid and the continuous phase -are immiscible. The magnetic properties of ionic liquids allow, through the influence of external magnetic fields, the manipulation of individual emulsion droplets such as capture and release, rotation and distortion. Arrays of magnets allow a coalescence of emulsion droplets and their subsequent mixing by flowing through an alternating permanent magnetic field. In addition, the double emulsion droplets can be split and reunified, or continuously separated into their original phases. PMID:24108233

  4. Rapid Analysis of the Internal Configurations of Droplets of Liquid Crystal using Flow Cytometry

    PubMed Central

    Miller, Daniel S.; Wang, Xiaoguang; Buchen, James; Lavrentovich, Oleg D.; Abbott, Nicholas L.

    2014-01-01

    We report the use of flow cytometry to identify the internal ordering (director configurations) of micrometer-sized droplets of thermotropic liquid crystals (LCs) dispersed in aqueous solutions of adsorbates (surfactants and phospholipids). We reveal that changes in the configurations of the LC droplets induced by the adsorbates generate distinct changes in light scattering plots (side versus forward scattering). Specifically, when compared to bipolar droplets, radial droplets generate a narrower distribution of side scattering intensities (SSC, large angle light scattering) for a given intensity of forward scattering (FSC, small angle light scattering). This difference is shown to arise from the rotational symmetry of a radial LC droplet which is absent for the bipolar configuration of the LC droplet. In addition, the scatter plots for radial droplets possess a characteristic “S-shape”, with two or more SSC intensities observed for each intensity of FSC. The origin of the experimentally observed S-shape is investigated via calculation of form factors and established to be due to size-dependent interference effects that differ for the forward and side scattered light. Finally, by analyzing emulsions comprised of mixtures of bipolar and radial droplets at rates of up to 10,000 droplets per second, we demonstrate that flow cytometry permits precise determination of the percentage of radial droplets within the mixture with a coefficient of determination of 0.98 (as validated by optical microscopy). Overall, the results presented in this paper demonstrate that flow cytometry provides a promising approach for high throughput quantification of the internal configurations of LC emulsion microdroplets. Because large numbers of droplets can be characterized, it enables statistically robust analyses of LC droplets. The methodology also appears promising for quantification of chemical and biological assays based on adsorbate-induced ordering transitions within LC droplets

  5. Excitation and dynamics of liquid tin micrometer droplet generation

    NASA Astrophysics Data System (ADS)

    Rollinger, B.; Abhari, R. S.

    2016-07-01

    The dynamics of capillary breakup-based droplet generation are studied for an excitation system based on a tunable piezoelectrically actuated oscillating piston, which generates acoustic pressure waves at the dispenser nozzle. First, the non-ideal pressure boundary conditions of droplet breakup are measured using a fast response pressure probe. A structural analysis shows that the axial modes of the excitation system are the main reasons for the resonance peaks in the pressure response. Second, a correlation between the nozzle inlet pressure and the droplet timing jitter is established with the help of experiments and a droplet formation model. With decreasing wave number, the growth rate of the main excitation decreases, while noise contributions with wave numbers with higher growth rates lead to a non-deterministic structure of the droplet train. A highly coherent and monodisperse droplet stream is obtained when the excitation system is tuned to generate high acoustic pressures at the desired operation frequency and when the noise level on the jet is limited. The jet velocity, hence droplet spacing for a set frequency is then adjusted by varying the reservoir pressure, according to the trade-off between lowest wave number and acceptable timing jitter.

  6. Evaporation of Liquid Droplet in Nano and Micro Scales from Statistical Rate Theory.

    PubMed

    Duan, Fei; He, Bin; Wei, Tao

    2015-04-01

    The statistical rate theory (SRT) is applied to predict the average evaporation flux of liquid droplet after the approach is validated in the sessile droplet experiments of the water and heavy water. The steady-state experiments show a temperature discontinuity at the evaporating interface. The average evaporation flux is evaluated by individually changing the measurement at a liquid-vapor interface, including the interfacial liquid temperature, the interfacial vapor temperature, the vapor-phase pressure, and the droplet size. The parameter study shows that a higher temperature jump would reduce the average evaporation flux. The average evaporation flux can significantly be influenced by the interfacial liquid temperature and the vapor-phase pressure. The variation can switch the evaporation into condensation. The evaporation flux is found to remain relative constant if the droplet is larger than a micro scale, while the smaller diameters in nano scale can produce a much higher evaporation flux. In addition, a smaller diameter of droplets with the same liquid volume has a larger surface area. It is suggested that the evaporation rate increases dramatically as the droplet shrinks into nano size.

  7. Experimental Study of Nonane and Nonane/Hexanol Fuel Droplet Combustion in Microgravity

    NASA Technical Reports Server (NTRS)

    Avedisian, C. T.; Callahan, B. J.

    1999-01-01

    In this presentation we review experiments carried out on nonane droplets, and a nonane/hexanol droplet, burning in microgravity to promote spherical symmetry. The nonane/hexanol combination was selected for the following reasons: 1) the spherically symmetric burning history of nonane and nonane/hexanol mixtures has not been previously studied; 2) measurements of the burning history of pure nonane droplets in air extend the existing data base of spherical droplet flames of soot-producing fuels which are useful for testing detailed chemical kinetic models of the spherically symmetric droplet burning process; 3) nonane and hexanol have almost identical boiling points so heterogeneous nucleation on a support fiber is unlikely; 4) hexanol does not have a strong propensity for water vapor absorption; 5) hexanol produces less soot than nonane so that mixtures of nonane and hexanol should show an effect of composition on soot formation. The far-field gas was atmospheric pressure air at room temperature. The evolution of droplet diameter was measured using high speed cine photography of spark-ignited droplets within a confined volume in a drop tower. The importance of soot formation during droplet combustion is derived from the fact that soot is the basic component of the particulate emission process that occurs in spray combustion. The complexity of soot formation motivates a one-dimensional transport condition which is advantageous for modeling. Recent numerical studies of droplet combustion have assumed spherical symmetry when incorporating such aspects as detailed chemistry and radiation, though soot formation itself has not yet been included in any droplet combustion modeling effort. If radiation is not important as would be the case for'small' droplets (i.e., droplets with initial diameters less than about ]mm), soot formation can lead to a nonlinear burning process and a time-varying burning rate, (non-linear burning of a non-sooting fuel like methanol is due to

  8. Effect of a Surrounding Liquid Environment on the Electrical Disruption of Pendant Droplets.

    PubMed

    Mohamed, A Said; Lopez-Herrera, Jose M; Herrada, Miguel A; Modesto-Lopez, Luis B; Gañán-Calvo, Alfonso M

    2016-07-12

    The effect of a surrounding, dielectric, liquid environment on the dynamics of a suddenly electrified liquid drop is investigated both numerically and experimentally. The onset of stability of the droplet is naturally dictated by a threshold value of the applied electric field. While below that threshold the droplet retains its integrity, reaching to a new equilibrium state through damped oscillations (subcritical regime), above it electrical disruption takes place (supercritical regime). In contrast to the oscillation regime, the dynamics of the electric droplet disruption in the supercritical regime reveals a variety of modes. Depending on the operating parameters and fluid properties, a drop in the supercritical regime may result in the well-known tip streaming mode (with and without whipping instability), in droplet splitting (splitting mode), or in the development of a steep shoulder at the elongating front of the droplet that expands radially in a sort of "splashing" (splashing mode). In both splitting and splashing modes, the sizes of the progeny droplets, generated after the breakup of the mother droplet, are comparable to that of the mother droplet. Furthermore, the development in the emission process of the shoulder leading to the splashing mode is described as a parametrical bifurcation, and the parameter governing that bifurcation has been identified. Physical analysis confirms the unexpected experimental finding that the viscosity of the dynamically active environment is absent in the governing parameter. However, the appearance of the splitting mode is determined by the viscosity of the outer environment, when that viscosity overcomes a certain large value. These facts point to the highly nonlinear character of the drop fission process as a function of the droplet volume, inner and outer liquid viscosities, and applied electric field. These observations may have direct implications in systems where precise control of the droplet size is critical, such

  9. Effect of a Surrounding Liquid Environment on the Electrical Disruption of Pendant Droplets.

    PubMed

    Mohamed, A Said; Lopez-Herrera, Jose M; Herrada, Miguel A; Modesto-Lopez, Luis B; Gañán-Calvo, Alfonso M

    2016-07-12

    The effect of a surrounding, dielectric, liquid environment on the dynamics of a suddenly electrified liquid drop is investigated both numerically and experimentally. The onset of stability of the droplet is naturally dictated by a threshold value of the applied electric field. While below that threshold the droplet retains its integrity, reaching to a new equilibrium state through damped oscillations (subcritical regime), above it electrical disruption takes place (supercritical regime). In contrast to the oscillation regime, the dynamics of the electric droplet disruption in the supercritical regime reveals a variety of modes. Depending on the operating parameters and fluid properties, a drop in the supercritical regime may result in the well-known tip streaming mode (with and without whipping instability), in droplet splitting (splitting mode), or in the development of a steep shoulder at the elongating front of the droplet that expands radially in a sort of "splashing" (splashing mode). In both splitting and splashing modes, the sizes of the progeny droplets, generated after the breakup of the mother droplet, are comparable to that of the mother droplet. Furthermore, the development in the emission process of the shoulder leading to the splashing mode is described as a parametrical bifurcation, and the parameter governing that bifurcation has been identified. Physical analysis confirms the unexpected experimental finding that the viscosity of the dynamically active environment is absent in the governing parameter. However, the appearance of the splitting mode is determined by the viscosity of the outer environment, when that viscosity overcomes a certain large value. These facts point to the highly nonlinear character of the drop fission process as a function of the droplet volume, inner and outer liquid viscosities, and applied electric field. These observations may have direct implications in systems where precise control of the droplet size is critical, such

  10. The liquid droplet radiator - An ultralightweight heat rejection system for efficient energy conversion in space

    NASA Technical Reports Server (NTRS)

    Mattick, A. T.; Hertzberg, A.

    1981-01-01

    A heat rejection system for space is described which uses a recirculating free stream of liquid droplets in place of a solid surface to radiate waste heat. By using sufficiently small droplets (less than about 100 micron diameter) of low vapor pressure liquids (tin, tin-lead-bismuth eutectics, vacuum oils) the radiating droplet sheet can be made many times lighter than the lightest solid surface radiators (heat pipes). The liquid droplet radiator (LDR) is less vulnerable to damage by micrometeoroids than solid surface radiators, and may be transported into space far more efficiently. Analyses are presented of LDR applications in thermal and photovoltaic energy conversion which indicate that fluid handling components (droplet generator, droplet collector, heat exchanger, and pump) may comprise most of the radiator system mass. Even the unoptimized models employed yield LDR system masses less than heat pipe radiator system masses, and significant improvement is expected using design approaches that incorporate fluid handling components more efficiently. Technical problems (e.g., spacecraft contamination and electrostatic deflection of droplets) unique to this method of heat rejection are discussed and solutions are suggested.

  11. The Liquid Droplet Radiator - an Ultralightweight Heat Rejection System for Efficient Energy Conversion in Space

    NASA Technical Reports Server (NTRS)

    Mattick, A. T.; Hertzberg, A.

    1984-01-01

    A heat rejection system for space is described which uses a recirculating free stream of liquid droplets in place of a solid surface to radiate waste heat. By using sufficiently small droplets ( 100 micron diameter) of low vapor pressure liquids the radiating droplet sheet can be made many times lighter than the lightest solid surface radiators (heat pipes). The liquid droplet radiator (LDR) is less vulnerable to damage by micrometeoroids than solid surface radiators, and may be transported into space far more efficiently. Analyses are presented of LDR applications in thermal and photovoltaic energy conversion which indicate that fluid handling components (droplet generator, droplet collector, heat exchanger, and pump) may comprise most of the radiator system mass. Even the unoptimized models employed yield LDR system masses less than heat pipe radiator system masses, and significant improvement is expected using design approaches that incorporate fluid handling components more efficiently. Technical problems (e.g., spacecraft contamination and electrostatic deflection of droplets) unique to this method of heat rejectioon are discussed and solutions are suggested.

  12. Stationary Liquid Fuel Fast Reactor

    SciTech Connect

    Yang, Won Sik; Grandy, Andrew; Boroski, Andrew; Krajtl, Lubomir; Johnson, Terry

    2015-09-30

    For effective burning of hazardous transuranic (TRU) elements of used nuclear fuel, a transformational advanced reactor concept named SLFFR (Stationary Liquid Fuel Fast Reactor) was proposed based on stationary molten metallic fuel. The fuel enters the reactor vessel in a solid form, and then it is heated to molten temperature in a small melting heater. The fuel is contained within a closed, thick container with penetrating coolant channels, and thus it is not mixed with coolant nor flow through the primary heat transfer circuit. The makeup fuel is semi- continuously added to the system, and thus a very small excess reactivity is required. Gaseous fission products are also removed continuously, and a fraction of the fuel is periodically drawn off from the fuel container to a processing facility where non-gaseous mixed fission products and other impurities are removed and then the cleaned fuel is recycled into the fuel container. A reference core design and a preliminary plant system design of a 1000 MWt TRU- burning SLFFR concept were developed using TRU-Ce-Co fuel, Ta-10W fuel container, and sodium coolant. Conservative design approaches were adopted to stay within the current material performance database. Detailed neutronics and thermal-fluidic analyses were performed to develop a reference core design. Region-dependent 33-group cross sections were generated based on the ENDF/B-VII.0 data using the MC2-3 code. Core and fuel cycle analyses were performed in theta-r-z geometries using the DIF3D and REBUS-3 codes. Reactivity coefficients and kinetics parameters were calculated using the VARI3D perturbation theory code. Thermo-fluidic analyses were performed using the ANSYS FLUENT computational fluid dynamics (CFD) code. Figure 0.1 shows a schematic radial layout of the reference 1000 MWt SLFFR core, and Table 0.1 summarizes the main design parameters of SLFFR-1000 loop plant. The fuel container is a 2.5 cm thick cylinder with an inner radius of 87.5 cm. The fuel

  13. Immobilization of Polymer-Decorated Liquid Crystal Droplets on Chemically Tailored Surfaces

    PubMed Central

    Kinsinger, Michael I.; Buck, Maren E.; Abbott, Nicholas L.; Lynn, David M.

    2010-01-01

    We demonstrate that the assembly of an amphiphilic polyamine on the interfaces of micrometer-sized droplets of a thermotropic liquid crystal (LC) dispersed in aqueous solutions can be used to facilitate the immobilization of LC droplets on chemically functionalized surfaces. Polymer 1 was designed to contain both hydrophobic (alkyl-functionalized) and hydrophilic (primary and tertiary amine-functionalized) side chain functionality. The assembly of this polymer at the interfaces of aqueous dispersions of LC droplets was achieved by spontaneous adsorption of polymer from aqueous solution. Polymer adsorption triggered transitions in the orientational ordering of the LCs, as observed by polarized light and bright-field microscopy. We demonstrate that the presence of polymer 1 on the interfaces of these droplets can be exploited to immobilize LC droplets on planar solid surfaces through covalent bond formation (e.g., for surfaces coated with polymer multilayers containing reactive azlactone functionality) or through electrostatic interactions (e.g., for surfaces coated with multilayers containing hydrolyzed azlactone functionality). Characterization of immobilized LC droplets by polarized, fluorescence, and laser scanning confocal microscopy revealed the general spherical shape of the polymer-coated LC droplets to be maintained after immobilization, and that immobilization led to additional ordering transitions within the droplets that was dependent on the nature of the surfaces with which they were in contact. Polymer 1-functionalized LC droplets were not immobilized on polymer multilayers treated with poly(ethylene imine) (PEI). We demonstrate that the ability to design surfaces that promote or prevent the immobilization of polymer-functionalized LC droplets can exploited to pattern the immobilization of LC droplets on surfaces. The results of this investigation provide the basis of an approach that could be used to tailor the properties of dispersed LC emulsions and

  14. Modelling of automotive fuel droplet heating and evaporation: mathematical tools and approximations

    NASA Astrophysics Data System (ADS)

    Sazhin, Sergei S.; Qubeissi, Mansour Al

    2016-06-01

    New mathematical tools and approximations developed for the analysis of automotive fuel droplet heating and evaporation are summarised. The approach to modelling biodiesel fuel droplets is based on the application of the Discrete Component Model (DCM), while the approach to modelling Diesel fuel droplets is based on the application of the recently developed multi-dimensional quasi-discrete model. In both cases, the models are applied in combination with the Effective Thermal Conductivity/Effective Diffusivity model and the implementation in the numerical code of the analytical solutions to heat transfer and species diffusion equations inside droplets. It is shown that the approximation of biodiesel fuel by a single component leads to under-prediction of droplet evaporation time by up to 13% which can be acceptable as a crude approximation in some applications. The composition of Diesel fuel was simplified and reduced to only 98 components. The approximation of 98 components of Diesel fuel with 15 quasi-components/components leads to under-prediction of droplet evaporation time by about 3% which is acceptable in most engineering applications. At the same time, the approximation of Diesel fuel by a single component and 20 alkane components leads to a decrease in the evaporation time by about 19%, compared with the case of approximation of Diesel fuel with 98 components. The approximation of Diesel fuel with a single alkane quasi-component (C14.763H31.526) leads to under-prediction of the evaporation time by about 35% which is not acceptable even for qualitative analysis of the process. In the case when n-dodecane is chosen as the single alkane component, the above-mentioned under-prediction increases to about 44%.

  15. Validated Numerical Models for the Convective Extinction of Fuel Droplets (CEFD)

    NASA Technical Reports Server (NTRS)

    Gogos, George; Bowen, Brent; Nickerson, Jocelyn S.

    2002-01-01

    The NASA Nebraska Space Grant (NSGC) & EPSCoR programs have continued their effort to support outstanding research endeavors by funding the Numerical Simulation of the Combustion of Fuel Droplets study at the University of Nebraska at Lincoln (UNL). This team of researchers has developed a transient numerical model to study the combustion of suspended and moving droplets. The engines that propel missiles, jets, and many other devices are dependent upon combustion. Therefore, data concerning the combustion of fuel droplets is of immediate relevance to aviation and aeronautical personnel, especially those involved in flight operations. The experiments being conducted by Dr. Gogos and Dr. Nayagam s research teams, allow investigators to gather data for comparison with theoretical predictions of burning rates, flame structures, and extinction conditions. The consequent improved fundamental understanding of droplet combustion may contribute to the clean and safe utilization of fossil fuels (Williams, Dryer, Haggard & Nayagam, 1997, f 2). The present state of knowledge on convective extinction of fuel droplets derives from experiments conducted under normal gravity conditions. However, any data obtained with suspended droplets under normal gravity are grossly affected by gravity. The need to obtain experimental data under microgravity conditions is therefore well justified and addresses one of the goals of NASA's Human Exploration and Development of Space (HEDS) microgravity combustion experiment.

  16. On the Shape of Liquid Metal Droplets in Electromagnetic Levitation Experiments

    NASA Technical Reports Server (NTRS)

    Schwartz, E.; Sauerland, S.; Szekely, J.; Egry, I.

    1993-01-01

    We present calculations and measurements on the shape of liquid metal droplets in electromagnetic levitation experiments. A normal stress balance model was developed to predict the shapes of liquid metal droplets that will be obtained in a microgravity experiment to measure the viscosity and surface tension of undercooled metals. This model was tested by calculating the droplet shapes in containerless experiments conducted to determine the surface tension of liquid metals. Inconsistencies associated with the results of a previous paper are elucidated. The computational results of the mathematical model are compared with the results of ground-based experiments for two different metals. The importance of the ratio of electromagnetic skin depth-to-droplet radius to the accuracy of the mathematical model is discussed. A planned alternate approach to modeling the shape by consideration of the entire droplet rather than only the surface is presented. As an example of an application. the influence of the shape on the splitting of the surface oscillation modes of levitated liquid metal droplets is discussed.

  17. Hydrodynamic directional control of liquid metal droplets within a microfluidic flow focusing system

    NASA Astrophysics Data System (ADS)

    Gol, Berrak; Kurdzinski, Michael E.; Tovar-Lopez, Francisco J.; Petersen, Phred; Mitchell, Arnan; Khoshmanesh, Khashayar

    2016-04-01

    Here, we investigate the directional control of Galinstan liquid metal droplets when transferring from the high-viscosity glycerol core into the parallel low-viscosity NaOH sheath streams within a flow focusing microfluidic system. In the presence of sufficient flow mismatch between the sheath streams, the droplets are driven toward the higher velocity interface and cross the interface under the influence of surface tension gradient. A minimum flow mismatch of 125 μl/min is required to enable the continuous transfer of droplets toward the desired sheath stream. The response time of droplets, the time required to change the direction of droplet transfer, is governed by the response time of the syringe pump driven microfluidic system and is found to be 3.3 and 8.8 s when increasing and decreasing the flow rate of sheath stream, respectively.

  18. Droplet impact on a liquid pool and bubble entrainment for low Bond numbers

    NASA Astrophysics Data System (ADS)

    Sleutel, Pascal; Tsai, Pei Hsun; Bouwhuis, Wilco; Thoraval, Marie-Jean; Visser, Claas-Willem; Wang, An-Bang; Versluis, Michel; Lohse, Detlef

    2015-11-01

    Droplets impacting on a pool of liquid and the subsequent bubble entrainment has been well studied for high Bond numbers where the droplets size is large and velocities are low. Here we study for the first time the droplet impact and bubble entrainment in an entirely new parameter regime (Bo ~ 10-2 -10-3 , U ~ 6-20 m/s, D ~ 0.08-0.4 mm). We follow up on the pioneering work of Oguz & Prosperetti, now in the surface tension dominated regime. We predict the bubble entrainment zone by balancing movement of the cavity bottom and droplet inertia with capillary waves enclosing the bubble. Both high-speed imaging experiments and numerical simulations in Gerris validate the model and show the importance of air for smaller droplet sizes.

  19. Growth Kinetics of Intracellular RNA/Protein Droplets: Signature of a Liquid-Liquid Phase Transition?

    NASA Astrophysics Data System (ADS)

    Berry, Joel; Weber, Stephanie C.; Vaidya, Nilesh; Zhu, Lian; Haataja, Mikko; Brangwynne, Clifford P.

    2015-03-01

    Nonmembrane-bound organelles are functional, dynamic assemblies of RNA and/or protein that can self-assemble and disassemble within the cytoplasm or nucleoplasm. The possibility that underlying intracellular phase transitions may drive and mediate the morphological evolution of some membrane-less organelles has been supported by several recent studies. In this talk, results from a collaborative experimental-theoretical study of the growth and dissolution kinetics of nucleoli and extranucleolar droplets (ENDs) in C. elegans embryos will be presented. We have employed Flory-Huggins solution theory, reaction-diffusion kinetics, and quantitative statistical dynamic scaling analysis to characterize the specific growth mechanisms at work. Our findings indicate that both in vivo and in vitro droplet scaling and growth kinetics are consistent with those resulting from an equilibrium liquid-liquid phase transition mediated by passive nonequilibrium growth mechanisms - simultaneous Brownian coalescence and Ostwald ripening. This supports a view in which cells can employ phase transitions to drive structural organization, while utilizing active processes, such as local transcriptional activity, to fine tune the kinetics of these phase transitions in response to given conditions.

  20. Numerical study of droplet dynamics in a polymer electrolyte fuel cell gas channel using an embedded Eulerian-Lagrangian approach

    NASA Astrophysics Data System (ADS)

    Jarauta, Alex; Ryzhakov, Pavel; Secanell, Marc; Waghmare, Prashant R.; Pons-Prats, Jordi

    2016-08-01

    An embedded Eulerian-Lagrangian formulation for the simulation of droplet dynamics within a polymer electrolyte fuel cell (PEFC) channel is presented. Air is modeled using an Eulerian formulation, whereas water is described with a Lagrangian framework. Using this framework, the gas-liquid interface can be accurately identified. The surface tension force is computed using the curvature defined by the boundary of the Lagrangian mesh. The method naturally accounts for material property changes across the interface and accurately represents the pressure discontinuity. A sessile drop in a horizontal surface, a sessile drop in an inclined plane and droplets in a PEFC channel are solved for as numerical examples and compared to experimental data. Numerical results are in excellent agreement with experimental data. Numerical results are also compared to results obtained with the semi-analytical model previously developed by the authors in order to discuss the limitations of the semi-analytical approach.

  1. High effectiveness liquid droplet/gas heat exchanger for space power applications

    NASA Technical Reports Server (NTRS)

    Bruckner, A. P.; Mattick, A. T.

    1983-01-01

    A high-effectiveness liquid droplet/gas heat exchanger (LDHX) concept for thermal management in space is described. Heat is transferred by direct contact between fine droplets (approx. 100 to 300 micron diameter) of a suitable low vapor pressure liquid and an inert working gas. Complete separation of the droplet and gas media in the zero-g environment is accomplished by configuring the LDHX as a vortex chamber. The large heat transfer area presented by the small droplets permits heat exchanger effectiveness of 0.9 to 0.95 in a compact, lightweight geometry which avoids many of the limitations of conventional plate and fin or tube and shell heat exchangers, such as their tendency toward single point failure. The application of the LDHX in a high temperature Bryaton cycle is discussed to illustrate the performance and operational characteristics of this heat exchanger concept.

  2. High effectiveness liquid droplet/gas heat exchanger for space power applications

    NASA Technical Reports Server (NTRS)

    Bruckner, A. P.; Mattick, A. T.

    1983-01-01

    A high-effectiveness liquid droplet/gas heat exchanger (LDHX) concept for thermal management in space is described. Heat is transferred by direct contact between fine droplets (approximately 100-300 microns in diameter) of a suitable low vapor pressure liquid and an inert working gas. Complete separation of the droplet and gas media in the zero-g environment is accomplished by configuring the LDHX as a vortex chamber.The large heat transfer area presented by the small droplets permits heat exchanger effectiveness of 0.9-0.95 in a compact, lightweight geometry which avoids many of the limitations of conventional plate and fin or tube and shell heat exchangers, such as their tendency toward single point failure. The application of the LDHX in a high temperature Brayton cycle is discussed to illustrate the performance and operational characteristics of this new heat exchanger concept.

  3. Liquid jet breakup and subsequent droplet dynamics under normal gravity and in microgravity conditions

    NASA Astrophysics Data System (ADS)

    Suñol, Francesc; González-Cinca, Ricard

    2015-07-01

    We present an experimental study on the characteristics of liquid jets in different configurations. We consider jets injected perpendicular to gravity, jets injected parallel to gravity, and jets injected in a microgravity environment. We study the role played by gravity in the jet breakup length and in the dynamics of the droplets generated after breakup. We analyze droplets obtained in the dripping and jetting regimes, focusing the study on their size, trajectory, oscillation, and rotation. The particularities of the considered injection configurations are analyzed. In normal gravity conditions, in the dripping and jetting regimes, the breakup length increases with the Weber number. The transition between these regimes occurs at Wecr ≈ 3.2. Droplets are notably larger in the dripping regime than in the jetting one. In the latter case, droplet mean size decreases as the liquid flow rate is increased. In microgravity conditions, droplet trajectories form a conical shape due to droplet bouncing after collision. When a collision takes place, coalescence tends to occur at low modified Weber numbers (Wem < 2) while bouncing is observed at higher values (Wem > 2). The surface of a droplet oscillates after bouncing or coalescence events, following a damped oscillator behavior. The observed oscillation frequency agrees with theoretical predictions.

  4. Burning of a spherical fuel droplet in a uniform subsonic flowfield

    SciTech Connect

    Madooglu, K.; Karagozian, A.R.

    1989-01-01

    An analytical/numerical model is described for the evaporation and burning of a spherical fuel droplet in a subsonic crossflow. The external gaseous flowfield is represented using an approximate compressible potential solution, while the internal flowfield of the droplet is represented by the classical Hill's spherical vortex. This allows numerical solution for the external boundary layer and diffusion flame characteristics to be made, from which the droplet's effective drag coefficient, rate of mass loss, size, and flame shape are determined. Comparison with experimental data indicate good agreement, and thus the potential for such simplified models in performing parametric studies.

  5. Nano-sized fine droplets of liquid crystals for optical application

    SciTech Connect

    Matsumoto, Shiro; Houlbert, M.; Hayashi, Takayoshi; Kubodera, Kenichi

    1997-09-01

    Nano-sized fine droplets of liquid crystal (LC) were obtained by phase separation of nematic LC in UV curing polymer. The polymer composite had a high transparency in the infrared region. The fine droplets responded to an electric field causing a change in birefringence. Output power change was brought about by the generated retardation between two polarizations, parallel and perpendicular to the applied electric field. This differs from the composite containing much larger droplets, where output depends on the degree of scattering. The birefringence changed by 0.001 at the applied voltage of 7.5 V/{micro}m.

  6. Liquid droplet radiator development status. [waste heat rejection devices for future space vehicles

    NASA Technical Reports Server (NTRS)

    White, K. Alan, III

    1987-01-01

    Development of the Liquid Droplet Radiator (LDR) is described. Significant published results of previous investigators are presented, and work currently in progress is discussed. Several proposed LDR configurations are described, and the rectangular and triangular configurations currently of most interest are examined. Development of the droplet generator, collector, and auxiliary components are discussed. Radiative performance of a droplet sheet is considered, and experimental results are seen to be in very good agreement with analytical predictions. The collision of droplets in the droplet sheet, the charging of droplets by the space plasma, and the effect of atmospheric drag on the droplet sheet are shown to be of little consequence, or can be minimized by proper design. The LDR is seen to be less susceptible than conventional technology to the effects of micrometeoroids or hostile threats. The identification of working fluids which are stable in the orbital environments of interest is also made. Methods for reducing spacecraft contamination from an LDR to an acceptable level are discussed. Preliminary results of microgravity testing of the droplet generator are presented. Possible future NASA and Air Force missions enhanced or enabled by a LDR are also discussed. System studies indicate that the LDR is potentially less massive than heat pipe radiators. Planned microgravity testing aboard the Shuttle or space station is seen to be a logical next step in LDR development.

  7. Spray Characterization of Gas-to-Liquid Synthetic Jet Fuels

    NASA Astrophysics Data System (ADS)

    Kannaiyan, Kumaran; Sadr, Reza

    2011-11-01

    In the recent years, development of alternative jet fuels is gaining importance owing to the demand for cleaner combustion. In addition to having energy density that matches those of conventional fuels, alternate jet fuels need to possess vital qualities such as rapid atomization and vaporization, quick re-ignition at high altitude, less emission, and poses ease of handling. The fuel preparatory steps (atomization and vaporization) and mixing in a combustion chamber play a crucial role on the subsequent combustion and emission characteristics. Gas-to-Liquid (GTL) synthetic jet fuel obtained from Fischer-Tropsch synthesis has grabbed the global attention due to its cleaner combustion characteristics as a result of the absence of aromatics and sulphur. As a part of an on-going joint effort between Texas A&M at Qatar (TAMUQ), Rolls-Royce (UK), and German Aerospace Laboratory (DLR), a spray characterization experimental facility is set up at TAMUQ to study the spray characteristics of GTL fuel and highlights the influence of change in fuel composition on the spray characteristics. In this work, spray characteristics such as droplet size, velocity, and distribution of different GTL fuel blends is investigated and compared with the spray characteristics of conventional JetA1 fuel. Supported by Qatar Science and Technology Park, QSTP.

  8. Gas and liquid fuel injection into an enclosed swirling flow

    NASA Astrophysics Data System (ADS)

    Ahmad, N. T.; Andrews, G. E.

    1984-06-01

    The use of swirler air for atomization has been tested with direct central propane injection and with direct central kerosene and gas oil injection, and its results have been compared with those for nonswirling flow systems under the same conditions. Direct propane injection results in a major extension of stability limits, by comparison to results for premixing, while with liquid fuel injection the stability limits are generally worse than for premixed fuel and air. This may be due to the action of the centrifugal forces on the liquid droplets in the swirl flow, which results in outer swirl flow vaporization and weaker mixtures in the core recirculation region than would be the case for propane injection. A comparison with nonswirling system performance indicated that all emission levels were higher with swirl for propane.

  9. Process for vaporizing a liquid hydrocarbon fuel

    DOEpatents

    Szydlowski, Donald F.; Kuzminskas, Vaidotas; Bittner, Joseph E.

    1981-01-01

    The object of the invention is to provide a process for vaporizing liquid hydrocarbon fuels efficiently and without the formation of carbon residue on the apparatus used. The process includes simultaneously passing the liquid fuel and an inert hot gas downwardly through a plurality of vertically spaed apart regions of high surface area packing material. The liquid thinly coats the packing surface, and the sensible heat of the hot gas vaporizes this coating of liquid. Unvaporized liquid passing through one region of packing is uniformly redistributed over the top surface of the next region until all fuel has been vaporized using only the sensible heat of the hot gas stream.

  10. Method and system for low-NO.sub.x dual-fuel combustion of liquid and/or gaseous fuels

    SciTech Connect

    Gard, Vincent; Chojnacki, Dennis A; Rabovitser, Ioseph K

    2014-12-02

    A method and apparatus for combustion in which a pressurized preheated liquid fuel is atomized and a portion thereof flash vaporized, creating a mixture of fuel vapor and liquid droplets. The mixture is mixed with primary combustion oxidant, producing a fuel/primary oxidant mixture which is then injected into a primary combustion chamber in which the fuel/primary oxidant mixture is partially combusted, producing a secondary gaseous fuel containing hydrogen and carbon oxides. The secondary gaseous fuel is mixed with a secondary combustion oxidant and injected into the second combustion chamber wherein complete combustion of the secondary gaseous fuel is carried out. The resulting second stage flue gas containing very low amounts of NO.sub.x is then vented from the second combustion chamber.

  11. Low-temperature ignition of droplets of suspension organic water-carbon fuels

    NASA Astrophysics Data System (ADS)

    Nakoryakov, V. E.; Glushkov, D. O.; Kuznetsov, G. V.; Strizhak, P. A.

    2016-07-01

    The conditions and integral characteristics of stable low-temperature ignition of droplets of suspension organic water-coal fuels are established by using the means of high-speed video-detection. The oxidizer temperature for these conditions varies in the range of 600-900 K (much below the temperatures in furnace chambers of modern power installations exceeding 1200 K). The velocity of the oxidizer-flow motion varies from 0.5 to 5 m/s, and the sizes (conditional radii) of droplets vary from 0.5 to 1.5 mm. The times of initiation of burning under conditions of low-temperature heating and the duration of the complete combustion of droplets of the corresponding compositions of organic water-coal fuels are determined. The necessary and sufficient conditions of stable ignition are singled out for promising organic water-coal fuels.

  12. Spreading of Thin Droplets of Perfect and Leaky Dielectric Liquids on Inclined Surfaces.

    PubMed

    Corbett, Andrew; Kumar, Satish

    2016-07-01

    The spreading of droplets may be influenced by electric fields, a situation that is relevant to applications such as coating, printing, and microfluidics. In this work we study the effects of an electric field on the gravity-driven spreading of two-dimensional droplets down an inclined plane. We consider both perfect and leaky dielectric liquids, as well as perfectly and partially wetting systems. In addition to the effects of electric fields, we examine the use of thermocapillary forces to suppress the growth of the capillary ridge near the droplet front. Lubrication theory is applied to generate a set of coupled partial differential equations for interfacial height and charge, which are then solved numerically with a finite-difference method. Electric fields increase the height of the capillary ridge in both perfect and leaky dielectric droplets due to electrostatic pressure gradients that drive liquid into the ridge. In leaky dielectrics, large interfacial charge gradients in the contact-line region create shear stresses that also enhance ridge growth and the formation of trailing minor ridges. The coalescence of these ridges can significantly affect the long-time thinning rate of leaky dielectric droplets. In partially wetting liquids, electric fields promote the splitting of smaller droplets from the primary droplet near the receding contact line due to the interplay between electrostatic forces and disjoining pressure. Cooling from below and heating from above generates thermocapillary forces that counteract the effects of electric fields and suppress the growth of the capillary ridge. The results of this work have important implications for manipulating the spreading of droplets down inclined surfaces. PMID:27247998

  13. Spreading of Thin Droplets of Perfect and Leaky Dielectric Liquids on Inclined Surfaces.

    PubMed

    Corbett, Andrew; Kumar, Satish

    2016-07-01

    The spreading of droplets may be influenced by electric fields, a situation that is relevant to applications such as coating, printing, and microfluidics. In this work we study the effects of an electric field on the gravity-driven spreading of two-dimensional droplets down an inclined plane. We consider both perfect and leaky dielectric liquids, as well as perfectly and partially wetting systems. In addition to the effects of electric fields, we examine the use of thermocapillary forces to suppress the growth of the capillary ridge near the droplet front. Lubrication theory is applied to generate a set of coupled partial differential equations for interfacial height and charge, which are then solved numerically with a finite-difference method. Electric fields increase the height of the capillary ridge in both perfect and leaky dielectric droplets due to electrostatic pressure gradients that drive liquid into the ridge. In leaky dielectrics, large interfacial charge gradients in the contact-line region create shear stresses that also enhance ridge growth and the formation of trailing minor ridges. The coalescence of these ridges can significantly affect the long-time thinning rate of leaky dielectric droplets. In partially wetting liquids, electric fields promote the splitting of smaller droplets from the primary droplet near the receding contact line due to the interplay between electrostatic forces and disjoining pressure. Cooling from below and heating from above generates thermocapillary forces that counteract the effects of electric fields and suppress the growth of the capillary ridge. The results of this work have important implications for manipulating the spreading of droplets down inclined surfaces.

  14. Skylab near-infrared observations of clouds indicating supercooled liquid water droplets

    NASA Technical Reports Server (NTRS)

    Curran, R. J.; Wu, M.-L. C.

    1982-01-01

    Orographically-induced lee-wave clouds were observed over New Mexico by a multichannel scanning radiometer on Skylab during December 1973. Channels centered at 0.83, 1.61 and 2.125 microns were used to determine the cloud optical thickness, thermodynamic phase and effective particle size. An additional channel centered at 11.4 microns was used to determine cloud-top temperature, which was corroborated through comparison with the stereographically determined cloud top altitudes and conventional temperature soundings. Analysis of the measured near-infrared reflection functions at 1.61 and 2.125 microns are most easily interpreted as indicating the presence of liquid-phase water droplets. This interpretation is not conclusive even after considerable effort to understand possible sources for misinterpretation. However, if accepted the resulting phase determination is considered anomalous due to the inferred cloud-top temperatures being in the -32 to -47 C range. Theory for the homogeneous nucleation of pure supercooled liquid water droplets predicts very short lifetimes for the liquid phase at these cold temperatures. A possible explanation for the observations is that the wave-clouds are composed of solution droplets. Impurities in the cloud droplets could decrease the homogeneous freezing rate for these droplets, permitting them to exist for a longer time in the liquid phase, at the cold temperatures found.

  15. Droplet charging regimes for ultrasonic atomization of a liquid electrolyte in an external electric field

    PubMed Central

    Forbes, Thomas P.; Degertekin, F. Levent; Fedorov, Andrei G.

    2011-01-01

    Distinct regimes of droplet charging, determined by the dominant charge transport process, are identified for an ultrasonic droplet ejector using electrohydrodynamic computational simulations, a fundamental scale analysis, and experimental measurements. The regimes of droplet charging are determined by the relative magnitudes of the dimensionless Strouhal and electric Reynolds numbers, which are a function of the process (pressure forcing), advection, and charge relaxation time scales for charge transport. Optimal (net maximum) droplet charging has been identified to exist for conditions in which the electric Reynolds number is of the order of the inverse Strouhal number, i.e., the charge relaxation time is on the order of the pressure forcing (droplet formation) time scale. The conditions necessary for optimal droplet charging have been identified as a function of the dimensionless Debye number (i.e., liquid conductivity), external electric field (magnitude and duration), and atomization drive signal (frequency and amplitude). The specific regime of droplet charging also determines the functional relationship between droplet charge and charging electric field strength. The commonly expected linear relationship between droplet charge and external electric field strength is only found when either the inverse of the Strouhal number is less than the electric Reynolds number, i.e., the charge relaxation is slower than both the advection and external pressure forcing, or in the electrostatic limit, i.e., when charge relaxation is much faster than all other processes. The analysis provides a basic understanding of the dominant physics of droplet charging with implications to many important applications, such as electrospray mass spectrometry, ink jet printing, and drop-on-demand manufacturing. PMID:21301636

  16. Spray Characterization of Gas-to-Liquid Synthetic Jet Fuels

    NASA Astrophysics Data System (ADS)

    Kannaiyan, Kumaran; Sadr, Reza; GTL jet fuel Consortium Team

    2012-11-01

    Gas-to-Liquid (GTL) Synthetic Paraffinic Kerosene (SPK) fuel obtained from Fischer-Tropsch synthesis has grabbed the global attention due to its cleaner combustion characteristics. GTL fuels are expected to meet the vital qualities such as atomization, combustion and emission characteristics of conventional jet fuels. It is imperative to understand fuel atomization in order to gain insights on the combustion and emission aspects of an alternative fuel. In this work spray characteristics of GTL-SPK, which could be used as a drop-in fuel in aircraft gas turbine engines, is studied. This work outlines the spray experimental facility, the methodology used and the results obtained using two SPK's with different chemical compositions. The spray characteristics, such as droplet size and distribution, are presented at three differential pressures across a simplex nozzle and compared with that of the conventional Jet A-1 fuel. Experimental results clearly show that although the chemical composition is significantly different between SPK's, the spray characteristics are not very different. This could be attributed to the minimal difference in fluid properties between the SPK's. Also, the spray characteristics of SPK's show close resemblance to the spray characteristics of Jet A-1 fuel.

  17. Collision Dynamics and Internal Mixing of Droplets of Non-Newtonian Liquids

    NASA Astrophysics Data System (ADS)

    Sun, Kai; Zhang, Peng; Law, Chung K.; Wang, Tianyou

    2015-11-01

    The efficient internal mixing of colliding droplets upon coalescence is critical to various technological processes such as color manipulation in ink-jet printing and the initiation of the liquid-phase reaction of gelled hypergolic propellants in rocket engines. Recognizing that such processes can be optimized by varying the impact inertia as well as employing fluids of non-Newtonian rheology, the head-on collision, coalescence, and internal mixing pattern between two impacting equal-sized droplets of non-Newtonian fluids is computationally investigated by using the lattice Boltzmann method. Results show that, with increasing non-Newtonian effects, droplet deformation and separation following coalescence is promoted for shear-thinning fluids, while permanent coalescence allowing an extended duration for mixing is promoted for shear-thickening fluids. Furthermore, large-scale internal mixing is promoted for the colliding droplets with larger shear-thinning disparity, while coalescence and mixing is synergistically facilitated for the collision between a shear-thinning droplet and a shear-thickening droplet. The individual and coupled influences of viscosity on the droplet deformation and impact inertia, internal motion, viscous loss, and merging of the colliding interfaces leading to the observed outcomes are mechanistically identified and described.

  18. Low contaminant formic acid fuel for direct liquid fuel cell

    DOEpatents

    Masel, Richard I.; Zhu, Yimin; Kahn, Zakia; Man, Malcolm

    2009-11-17

    A low contaminant formic acid fuel is especially suited toward use in a direct organic liquid fuel cell. A fuel of the invention provides high power output that is maintained for a substantial time and the fuel is substantially non-flammable. Specific contaminants and contaminant levels have been identified as being deleterious to the performance of a formic acid fuel in a fuel cell, and embodiments of the invention provide low contaminant fuels that have improved performance compared to known commercial bulk grade and commercial purified grade formic acid fuels. Preferred embodiment fuels (and fuel cells containing such fuels) including low levels of a combination of key contaminants, including acetic acid, methyl formate, and methanol.

  19. Nanoparticle self-assembly at the interface of liquid crystal droplets

    PubMed Central

    Rahimi, Mohammad; Roberts, Tyler F.; Armas-Pérez, Julio C.; Wang, Xiaoguang; Bukusoglu, Emre; Abbott, Nicholas L.; de Pablo, Juan J.

    2015-01-01

    Nanoparticles adsorbed at the interface of nematic liquid crystals are known to form ordered structures whose morphology depends on the orientation of the underlying nematic field. The origin of such structures is believed to result from an interplay between the liquid crystal orientation at the particles’ surface, the orientation at the liquid crystal’s air interface, and the bulk elasticity of the underlying liquid crystal. In this work, we consider nanoparticle assembly at the interface of nematic droplets. We present a systematic study of the free energy of nanoparticle-laden droplets in terms of experiments and a Landau–de Gennes formalism. The results of that study indicate that, even for conditions under which particles interact only weakly at flat interfaces, particles aggregate at the poles of bipolar droplets and assemble into robust, quantized arrangements that can be mapped onto hexagonal lattices. The contributions of elasticity and interfacial energy corresponding to different arrangements are used to explain the resulting morphologies, and the predictions of the model are shown to be consistent with experimental observations. The findings presented here suggest that particle-laden liquid crystal droplets could provide a unique and versatile route toward building blocks for hierarchical materials assembly. PMID:25870304

  20. Physical understanding of gas-liquid annular flow and its transition to dispersed droplets

    NASA Astrophysics Data System (ADS)

    Kumar, Parmod; Das, Arup Kumar; Mitra, Sushanta K.

    2016-07-01

    Transformation from annular to droplet flow is investigated for co-current, upward gas-liquid flow through a cylindrical tube using grid based volume of fluid framework. Three transitional routes, namely, orificing, rolling, and undercutting are observed for flow transformation at different range of relative velocities between the fluids. Physics behind these three exclusive phenomena is described using circulation patterns of gaseous phase in the vicinity of a liquid film which subsequently sheds drop leading towards transition. Orifice amplitude is found to grow exponentially towards the core whereas it propagates in axial direction in a parabolic path. Efforts have been made to fit the sinusoidal profile of wave structure with the numerical interface contour at early stages of orificing. Domination of gas inertia over liquid flow has been studied in detail at the later stages to understand the asymmetric shape of orifice, leading towards lamella formation and droplet generation. Away from comparative velocities, circulations in the dominant phase dislodge the drop by forming either a ligament (rolling) or a bag (undercut) like protrusion in liquid. Study of velocity patterns in the plane of droplet dislodge reveals the underlying physics behind the disintegration and its dynamics at the later stages. Using numerical phase distributions, rejoining of dislodged droplet with liquid film as post-rolling consequences has been also proposed. A flow pattern map showing the transitional boundaries based on the physical mechanism is constructed for air-water combination.

  1. Continuous Rotation of Achiral Nematic Liquid Crystal Droplets Driven by Heat Flux.

    PubMed

    Ignés-Mullol, Jordi; Poy, Guilhem; Oswald, Patrick

    2016-07-29

    Suspended droplets of cholesteric (chiral nematic) liquid crystals spontaneously rotate in the presence of a heat flux due to a temperature gradient, a phenomenon known as the Lehmann effect. So far, it is not clear whether this effect is due to the chirality of the phase and the molecules or only to the chirality of the director field. Here, we report the continuous rotation in a temperature gradient of nematic droplets of a lyotropic chromonic liquid crystal featuring a twisted bipolar configuration. The achiral nature of the molecular components leads to a random handedness of the spontaneous twist, resulting in the coexistence of droplets rotating in the two senses, with speeds proportional to the temperature gradient and inversely proportional to the droplet radius. This result shows that a macroscopic twist of the director field is sufficient to induce a rotation of the droplets, and that the phase and the molecules do not need to be chiral. This suggests that one can also explain the Lehmann rotation in cholesteric liquid crystals without introducing the Leslie thermomechanical coupling-only present in chiral mesophases. An explanation based on the Akopyan and Zeldovich theory of thermomechanical effects in nematics is proposed and discussed. PMID:27517793

  2. Experimental Investigation Evaporation of Liquid Mixture Droplets during Depressurization into Air Stream

    NASA Astrophysics Data System (ADS)

    Liu, L.; Bi, Q. C.; Terekhov, Victor I.; Shishkin, Nikolay E.

    2010-03-01

    The objective of this study is to develop experimental method to study the evaporation process of liquid mixture droplets during depressurization and into air stream. During the experiment, a droplet was suspended on a thermocouple; an infrared thermal imager was used to measure the droplet surface temperature transition. Saltwater droplets were used to investigate the evaporation process during depressurization, and volatile liquid mixtures of ethanol, methanol and acetone in water were applied to experimentally research the evaporation into air stream. According to the results, the composition and concentration has a complex influence on the evaporation rate and the temperature transition. With an increase in the share of more volatile component, the evaporation rate increases. While, a higher salt concentration in water results in a lower evaporation rate. The shape variation of saltwater droplet also depends on the mass concentration in solution, whether it is higher or lower than the eutectic point (22.4%). The results provide important insight into the complex heat and mass transfer of liquid mixture during evaporation.

  3. Continuous Rotation of Achiral Nematic Liquid Crystal Droplets Driven by Heat Flux

    NASA Astrophysics Data System (ADS)

    Ignés-Mullol, Jordi; Poy, Guilhem; Oswald, Patrick

    2016-07-01

    Suspended droplets of cholesteric (chiral nematic) liquid crystals spontaneously rotate in the presence of a heat flux due to a temperature gradient, a phenomenon known as the Lehmann effect. So far, it is not clear whether this effect is due to the chirality of the phase and the molecules or only to the chirality of the director field. Here, we report the continuous rotation in a temperature gradient of nematic droplets of a lyotropic chromonic liquid crystal featuring a twisted bipolar configuration. The achiral nature of the molecular components leads to a random handedness of the spontaneous twist, resulting in the coexistence of droplets rotating in the two senses, with speeds proportional to the temperature gradient and inversely proportional to the droplet radius. This result shows that a macroscopic twist of the director field is sufficient to induce a rotation of the droplets, and that the phase and the molecules do not need to be chiral. This suggests that one can also explain the Lehmann rotation in cholesteric liquid crystals without introducing the Leslie thermomechanical coupling—only present in chiral mesophases. An explanation based on the Akopyan and Zeldovich theory of thermomechanical effects in nematics is proposed and discussed.

  4. Combustion characteristics of fuel droplets with addition of nano and micron-sized aluminum particles

    SciTech Connect

    Gan, Yanan; Qiao, Li

    2011-02-15

    The burning characteristics of fuel droplets containing nano and micron-sized aluminum particles were investigated. Particle size, surfactant concentration, and the type of base fluid were varied. In general, nanosuspensions can last much longer than micron suspensions, and ethanol-based fuels were found to achieve much better suspension than n-decane-based fuels. Five distinctive stages (preheating and ignition, classical combustion, microexplosion, surfactant flame, and aluminum droplet flame) were identified for an n-decane/nano-Al droplet, while only the first three stages occurred for an n-decane/micron-Al droplet. For the same solid loading rate and surfactant concentration, the disruption and microexplosion behavior of the micron suspension occurred later with much stronger intensity. The intense droplet fragmentation was accompanied by shell rupture, which caused a massive explosion of particles, and most of them were burned during this event. On the contrary, for the nanosuspension, combustion of the large agglomerate at the later stage requires a longer time and is less complete because of formation of an oxide shell on the surface. This difference is mainly due to the different structure and characteristics of particle agglomerates formed during the early stage, which is a spherical, porous, and more-uniformly distributed aggregate for the nanosuspension, but it is a densely packed and impermeable shell for the micron suspension. A theoretical analysis was then conducted to understand the effect of particle size on particle collision mechanism and aggregation rate. The results show that for nanosuspensions, particle collision and aggregation are dominated by the random Brownian motion. For micron suspensions, however, they are dominated by fluid motion such as droplet surface regression, droplet expansion resulting from bubble formation, and internal circulation. And the Brownian motion is the least important. This theoretical analysis explains the

  5. Combustion of liquid fuels in a flowing combustion gas environment at high pressures

    NASA Technical Reports Server (NTRS)

    Canada, G. S.; Faeth, G. M.

    1975-01-01

    The combustion of fuel droplets in gases which simulate combustion chamber conditions was considered both experimentally and theoretically. The fuel droplets were simulated by porous spheres and allowed to gasify in combustion gases produced by a burner. Tests were conducted for pressures of 1-40 atm, temperatures of 600-1500 K, oxygen concentrations of 0-13% (molar) and approach Reynolds numbers of 40-680. The fuels considered in the tests included methanol, ethanol, propanol-1, n-pentane, n-heptane and n-decane. Measurements were made of both the rate of gasification of the droplet and the liquid surface temperature. Measurements were compared with theory, involving various models of gas phase transport properties with a multiplicative correction for the effect of forced convection.

  6. Liquid water content and droplet size calibration of the NASA Lewis Icing Research Tunnel

    NASA Technical Reports Server (NTRS)

    Ide, Robert F.

    1990-01-01

    The icing research tunnel at the NASA Lewis Research Center underwent a major rehabilitation in 1986 to 1987, necessitating recalibration of the icing cloud. The methods used in the recalibration, including the procedure used to establish a uniform icing cloud and the use of a standard icing blade technique for measurement of liquid water content are described. PMS Forward Scattering Spectrometer and Optical Array probes were used for measurement of droplet size. Examples of droplet size distributions are shown for several median volumetric diameters. Finally, the liquid water content/droplet size operating envelopes of the icing tunnel are shown for a range of airspeeds and are compared to the FAA icing certification criteria.

  7. Heat transfer and flow studies of the liquid droplet heat exchanger

    NASA Technical Reports Server (NTRS)

    Bruckner, A. P.; Shariatmadar, A.

    1987-01-01

    This paper describes a lightweight, highly effective liquid droplet heat exchanger (LDHX) concept for thermal management in space. Heat is transferred by direct contact between fine droplets (100 to 300 micron diameter) of a low vapor pressure liquid and an inert working gas. Complete separation of the droplet and gas media in the microgravity environment is accomplished by configuring the LDHX as a vortex chamber. A quasi-one-dimensional, two-phase heat transfer model of the LDHX is developed and used to investigate the potential use of the LDHX for both heating and cooling the working gas in a 100-k W(e) Braytoan cycle. Experimental studies on a small scale LDHX chamber, using air and water as the two media, show excellent agreement with the theoretical model.

  8. Liquid water content and droplet size calibration of the NASA Lewis Icing Research Tunnel

    NASA Technical Reports Server (NTRS)

    Ide, Robert F.

    1989-01-01

    The icing research tunnel at the NASA Lewis Research Center underwent a major rehabilitation in 1986 to 1987, necessitating recalibration of the icing cloud. The methods used in the recalibration, including the procedure used to establish a uniform icing cloud and the use of a standard icing blade technique for measurement of liquid water content are described. PMS Forward Scattering Spectrometer and Optical Array probes were used for measurement of droplet size. Examples of droplet size distributions are shown for several median volumetric diameters. Finally, the liquid water content/droplet size operating envelopes of the icing tunnel are shown for a range of airspeeds and are compared to the FAA icing certification criteria.

  9. Significance of droplet-droplet interactions in droplet streams: Atmospheric to supercritical conditions

    NASA Astrophysics Data System (ADS)

    Connon, Corinne Shirley

    In an effort to optimize liquid fuel combustion a considerable amount of research has been directed towards the atomization of large liquid masses into small droplets to increase the surface area available for vaporization. The current work uses a single linear array of moving droplets of uniform size and spacing to investigate the behavior of interacting droplets. A series of experiments, over a range of ambient conditions, demonstrate how a lead droplet alters the environment experienced by its trailing neighbor. This behavior is of particular interest for droplet groups under high pressure and temperature, where experimental data has been limited. Gas phase velocity and vapor concentration measurements show that as the space between adjacent droplets decreases entrainment of fluid towards the axis of motion is reduced. Trapped gases create a gaseous cylinder, composed of ambient gas and fuel vapor, which surrounds and moves with the droplet stream. As ambient pressure increase, the oscillatory behavior of the lead droplet wake begins to interfere with its trailing neighbor. Loss of stream stability and enhanced droplet stripping in part result from these oscillating wakes. However, acceleration of droplet stripping is mainly produced by liquid and gas density similarity, which increases the centrifugal stress and the growth rate of capillary waves. Further, injection of subcritical droplets into an ambient environment at temperatures and pressures above the liquid droplet critical point shows behavior not greatly different from the results obtained at high ambient pressures. The similarity results from thermal heatup times exceeding the breakup times generated from the severe aerodynamics encountered at high ambient density and high liquid-gas relative velocities.

  10. Thermocapillary migration of droplets in a transparent liquid mixture and a monotectic alloy melt

    NASA Astrophysics Data System (ADS)

    Klein, H.; Neumann, H.

    2003-08-01

    Experimental evidence of thermocapillary migration of droplets is reported in two different systems, a binary liquid mixture with miscibility gap and a monotectic alloy belt. Thermocapillary migration is monitored by video microscopy in the first and by using electrical resistance measurements in the second system.

  11. Liquid water transport in fuel cell gas diffusion layers

    NASA Astrophysics Data System (ADS)

    Bazylak, Aimy Ming Jii

    Liquid water management has a major impact on the performance and durability of the polymer electrolyte membrane fuel cell (PEMFC). The gas diffusion layer (GDL) of a PEMFC provides pathways for mass, heat, and electronic transport to and from the catalyst layers and bipolar plates. When the GDL becomes flooded with liquid water, the PEMFC undergoes mass transport losses that can lead to decreased performance and durability. The work presented in this thesis includes contributions that provide insight into liquid water transport behaviour in and on the surface of the GDL, as well as insight into how future GDLs could be designed to enhance water management. The effects of compression on liquid water transport in the GDL and on the microstructure of the GDL are presented. It was found that compressed regions of the GDL provided preferential locations for water breakthrough, while scanning electron microscopy (SEM) imaging revealed irreversible damage to the GDL due to compression at typical fuel cell assembly pressures. The dynamic behaviour of droplet emergence and detachment in a simulated gas flow channel are also presented. It was found that on an initially dry and hydrophobic GDL, small droplets emerged and detached quickly from the GDL surface. However, over time, this water transport regime transitioned into that of slug formation and channel flooding. It was observed that after being exposed to a saturated environment, the GDL surface became increasingly prone to droplet pinning, which ultimately hindered droplet detachment and encouraged slug formation. A pore network model featuring invasion percolation with trapping was employed to evaluate the breakthrough pattern predictions of designed porous media. These designed pore networks consisted of randomized porous media with applied diagonal and radial gradients. Experimental microfluidic pore networks provided validation for the designed networks. Diagonal biasing provided a means of directing water

  12. Near-global survey of effective droplet radii in liquid water clouds using ISCCP data

    NASA Technical Reports Server (NTRS)

    Han, Qingyan; Rossow, William B.; Lacis, Andrew B.

    1994-01-01

    A global survey of cloud particle size variations can provide crucial constraints on how cloud processes determine cloud liquid water contents and their variation with temperature, and further, may indicate the magnitude of aerosol effects on clouds. A method, based on a complete radiative transfer model for Advanced Very High Resolution Radiometer (AVHRR)-measured radiances, is described for retrieving cloud particle radii in liquid water clouds from satellite data currently available from the International Satellite Cloud Climatology Project. Results of sensitivity tests and validation studies provide error estimates. AVHRR data from NOAA-9 and NOAA-10 have been analyzed for January, April, July and October in 1987 and 1988. The results of this first survey reveal systematic continental and maritime differences and hemispheric contrasts that are indicative of the effects of associated aerosol concentration differences: cloud droplet radii in continental water clouds are about 2-3 micrometers smaller than in marine clouds, and droplet radii are about 1 micrometer smaller in marine clouds of the Northern Hemisphere than in the Southern Hemisphere. The height dependencies of cloud droplet radii in continental and marine clouds are also consistent with differences in the vertical profiles of aerosol concentration. Significant seasonal and diurnal variations of effective droplet radii are also observed, particularly at lower latitudes. Variations of the relationship between cloud optical thickness and droplet radii may indicate variations in cloud microphysical regimes.

  13. Diazido alkanes and diazido alkanols as combustion modifiers for liquid hydrocarbon ramjet fuels

    SciTech Connect

    Miller, R.S.

    1986-07-03

    This invention relates to liquid-hydrocarbon jet fuels and more particularly to azido additives to liquid-hydrocarbon ramjet fuels. In most liquid-fueled combustors such as the ramjet, the fuel is directly introduced into the upstream flow section of the combustion chamber in the form of sprays of droplets. These droplets subsequently mix with the external gas, heat up, gasify, combust, and thereby release heat to provide the propulsion energy. It is therefore obvious that the rates of gasification and mixing would closely affect the chemical heat release rate and, consequently, such important performance parameters as combustion efficiency and the tendency to exhibit combustion instability. Accordingly, and object of this invention is to provide a new, improved jet fuel and provide new additives for jet fuels. A further object of this invention is to provide a more-efficient jet fuel and reduce the ignition time for jet fuels. Still, a further object of this invention is to improve the mixing characteristics of the jet-fuel spray.

  14. Droplet impact dynamics for two liquids impinging on anisotropic superhydrophobic surfaces

    NASA Astrophysics Data System (ADS)

    Pearson, John T.; Maynes, Daniel; Webb, Brent W.

    2012-09-01

    Droplet impingement experiments were performed on grooved hydrophobic surfaces with cavity fractions of 0, 80, and 93 % using droplets of water and a 50 %/50 % water/glycerol mixture. The influence of liquid viscosity, cavity fraction, and spreading direction, relative to the surface grooves, is explored qualitatively and quantitatively. The maximum droplet spread diameter, velocity of the rebounding jet, and the time delay between droplet impact and jet emission were characterized for Weber numbers, We, based on droplet impact speed and diameter, up to 500. The unequal shear stresses and contact angles influence the maximum spread diameters in the two primary spread directions. At We > 100, the ratio of the spread diameter along the direction of the grooves to the spread diameter perpendicular to the grooves increases above unity with increasing We. The maximum droplet spread diameter is compared to recent predictive models, and the data reveal differing behavior for the two fluids considered. The results also reveal the existence of very high relative jet velocities in the range 5 ≤ We ≤ 15 for water droplets, while such jets were not observed for the more viscous mixture. Further, in the range 115 ≤ We ≤ 265, the water/glycerol jet formation dynamics are radically different from the water behavior. Most evident is the existence of two-pronged jets, which arise from the anisotropy of the surface and the unequal shear stresses and contact angles that prevail on the surfaces. It is these influences that give rise to differences in the maximum spread diameters in the two primary spread directions. Similar two-pronged jet emission was observed for water over the very narrow range of We from 91 to 96. The issuing jet velocities were also observed to increase with increasing cavity fraction for both fluids and over the entire range of We explored. Lastly, the elapsed time between droplet impact and jet emission decreased with increasing cavity fraction.

  15. Combustion characteristics in the transition region of liquid fuel sprays

    NASA Technical Reports Server (NTRS)

    Cernansky, N. P.; Namer, I.; Tidona, R. J.

    1986-01-01

    A number of important effects have been observed in the droplet size transition region in spray combustion systems. In this region, where the mechanism of flame propagation is transformed from diffusive to premixed dominated combustion, the following effects have been observed: (1) maxima in burning velocity; (2) extension of flammability limits; (3) minima in ignition energy; and (4) minima in NOx formation. A monodisperse aerosol generator has been used to form and deliver a well controlled liquid fuel spray to the combustion test section where measurements of ignition energy have been made. The ignition studies were performed on monodisperse n-heptane sprays at atmospheric pressure over a range of equivalence ratios and droplet diameters. A capacitive discharge spark ignition system was used as the ignition source, providing independent control of spark energy and duration. Preliminary measurements were made to optimize spark duration and spark gap, optimum conditions being those at which the maximum frequency or probability of ignition was observed. Using the optimum electrode spacing and spark duration, the frequency of ignition was determined as a function of spark energy for three overall equivalence ratios (0.6, 0.8, and 1.0) and for initial droplet diameters of 25, 40, 50, 60, and 70 micro m.

  16. Uranium droplet core nuclear rocket

    NASA Technical Reports Server (NTRS)

    Anghaie, Samim

    1991-01-01

    Uranium droplet nuclear rocket is conceptually designed to utilize the broad temperature range ofthe liquid phase of metallic uranium in droplet configuration which maximizes the energy transfer area per unit fuel volume. In a baseline system dissociated hydrogen at 100 bar is heated to 6000 K, providing 2000 second of Isp. Fission fragments and intense radian field enhance the dissociation of molecular hydrogen beyond the equilibrium thermodynamic level. Uranium droplets in the core are confined and separated by an axisymmetric vortex flow generated by high velocity tangential injection of hydrogen in the mid-core regions. Droplet uranium flow to the core is controlled and adjusted by a twin flow nozzle injection system.

  17. A New Finite-Conductivity Droplet Evaporation Model Including Liquid Turbulence Effect

    NASA Technical Reports Server (NTRS)

    Balasubramanyam, M. S.; Chen, C. P.; Trinh, H. P.

    2006-01-01

    A new approach to account for finite thermal conductivity and turbulence effects within atomizing droplets of an evaporating spray is presented in this paper. The model is an extension of the T-blob and T-TAB atomization/spray model of Trinh and Chen [9]. This finite conductivity model is based on the two-temperature film theory in which the turbulence characteristics of the droplet are used to estimate the effective thermal diffusivity for the liquid-side film thickness. Both one-way and two-way coupled calculations were performed to investigate the performance cf this model against the published experimental data.

  18. Response of two-phase droplets to intense electromagnetic radiation

    NASA Technical Reports Server (NTRS)

    Spann, James F.; Maloney, Daniel J.; Lawson, William F.; Casleton, Kent H.

    1993-01-01

    The behavior of two-phase droplets subjected to high intensity radiation pulses is studied. Droplets are highly absorbing solids in weakly absorbing liquid medium. The objective of the study was to define heating thresholds required for causing explosive boiling and secondary atomization of the fuel droplet. The results point to mechanisms for energy storage and transport in two-phase systems.

  19. Ignition of a floating droplet of organic coal-water fuel

    NASA Astrophysics Data System (ADS)

    Nakoryakov, V. E.; Kuznetsov, G. V.; Strizhak, P. A.

    2016-06-01

    The results of experimental investigations are presented for the ignition of droplets (particles) of organic coal-water fuels (OCWFs) floating in a flow of an oxidizer using a special combustion chamber from high-temperature quartz glass. The temperature and the velocity of motion of the oxidizer vary in the ranges of 500-900 K and 0.5-3 m/s. The initial sizes (radii) of fuel droplets amounted to 0.3-1.5 mm. As the basic OCWF components, particles (of 80-100 µm in size) of brown coal "B2," water, mazut, and waste castor and compressor oils are used. With use of the system of high-velocity video registration, the conditions providing for floating of OCWF particles without initiation of burning and with the subsequent steady ignition are established. Four modes of OCWF-droplet ignition with different trajectories of their motion in the combustion chamber are singled out. The times of the OCWF-ignition delay in dependence on the size of fuel particles and oxidizer temperatures are determined. The deviations of the OCWF-ignition-delay times obtained under conditions of suspension of a droplet on the thermocouple junction and while floating in the oxidizer flow are established.

  20. Liquid Fuels Market Module - NEMS Documentation

    EIA Publications

    2014-01-01

    Defines the objectives of the Liquid Fuels Market Model (LFMM), describes its basic approach, and provides detail on how it works. This report is intended as a reference document for model analysts, users, and the public.

  1. Study on secondary atomization of liquid fuel at the lip of the flameholder

    NASA Astrophysics Data System (ADS)

    Yang, Maolin; Huang, Yong; Gu, Shanjiang; Zhang, Yingnian

    1992-01-01

    An experimental investigation of secondary atomization of liquid fuel at the lip of the flameholder has been completed by means of the Malvern Particle-Sizer. This secondary atomization has several features: fine droplets occur in the high speed air flow side, while gross droplets occur in the recirculation zone side; the velocity of air flow has a predominant influence on the mean drop size of the spray which may be expressed quantitatively. The mechanism of the secondary atomization may be described as follows: some of the liquid drops in the spray are gathered by the flameholder and form a fuel film in its surface, the air flow forces the wavy film to move forward to the lip of the flameholder, and the fuel film breaks up at flameholder lip under a pincer attack of high speed turbulent flow and low speed recirculation flow.

  2. Process for preparing a liquid fuel composition

    DOEpatents

    Singerman, Gary M.

    1982-03-16

    A process for preparing a liquid fuel composition which comprises liquefying coal, separating a mixture of phenols from said liquefied coal, converting said phenols to the corresponding mixture of anisoles, subjecting at least a portion of the remainder of said liquefied coal to hydrotreatment, subjecting at least a portion of said hydrotreated liquefied coal to reforming to obtain reformate and then combining at least a portion of said anisoles and at least a portion of said reformate to obtain said liquid fuel composition.

  3. How faceted liquid droplets grow tails: from surface topology to active motion

    NASA Astrophysics Data System (ADS)

    Sloutskin, Eli

    Among all possible shapes of a volume V, a sphere has the smallest surface area A. Therefore, liquid droplets are spherical, minimizing their interfacial energy γA for a given interfacial tension γ > 0 . This talk will demonstrate that liquid oil (alkane) droplets in water, stabilized by a common surfactant can be temperature-tuned to adopt icosahedral and other faceted shapes, above the bulk melting temperature of the oil. Although emulsions have been studied for centuries no faceted liquid droplets have ever been reported. The formation of an icosahedral shape is attributed to the interplay between γ and the elastic properties of the interfacial monomolecular layer, which crystallizes here 10-15K above bulk melting, leaving the droplet's bulk liquid. The icosahedral symmetry is dictated by twelve five-fold topological defects, forming within the hexagonally-packed interfacial crystalline monolayer. Moreover, we demonstrate that upon further cooling this `interfacial freezing' effect makes γ transiently switch its sign, leading to a spontaneous splitting of droplets and an active growth of their surface area, reminiscent of the classical spontaneous emulsification, yet driven by completely different physics. The observed phenomena allow deeper insights to be gained into the fundamentals of molecular elasticity and open new vitas for a wide range of novel nanotechnological applications, from self-assembly of complex shapes to new delivery strategies in bio-medicine. Acknowledgment is made to the Donors of the American Chemical Society Petroleum Research Fund for support of this research and to the Kahn Foundation for the purchase of equipment.

  4. Experimental investigation on the effect of liquid injection by multiple orifices in the formation of droplets in a Venturi scrubber.

    PubMed

    Guerra, V G; Gonçalves, J A S; Coury, J R

    2009-01-15

    Venturi scrubbers are widely utilized in gas cleaning. The cleansing elements in these scrubbers are droplets formed from the atomization of a liquid into a dust-laden gas. In industrial scrubbers, this liquid is injected through several orifices so that the cloud of droplets can be evenly distributed throughout the duct. The interaction between droplets when injected through many orifices, where opposite clouds of atomized liquid can reach each other, is to be expected. This work presents experimental measurements of droplet size measured in situ and the evidence of cloud interaction within a Venturi scrubber operating with multi-orifice jet injection. The influence of gas velocity, liquid flow rate and droplet size variation in the axial position after the point of the injection of the liquid were also evaluated for the different injection configurations. The experimental results showed that an increase in the liquid flow rate generated greater interaction between jets. The number of orifices had a significant influence on droplet size. In general, the increase in the velocity of the liquid jet and in the gas velocity favored the atomization process by reducing the size of the droplets.

  5. Average size and size distribution of large droplets produced in a free-jet expansion of a liquid

    NASA Astrophysics Data System (ADS)

    Knuth, E. L.; Henne, U.

    1999-02-01

    The experimental parameters and fluid properties affecting the average size N¯ and the size distribution P(N) of droplets formed by fragmentation of a liquid after expansion into a vacuum are investigated. The mean droplet size is found to be a function of the surface tension of the liquid, the nozzle diameter, and a characteristic flow speed. The size distribution is found to be a linear exponential distribution; measurements deviate from this distribution at small sizes if a factor which is a function of the cluster size is included in the measuring process. Good agreement with measured distributions of both positive and negative droplet ions formed from neutral 4He droplets by electron impact is found. The strong dependence of mean droplet size on source-orifice diameter found in the present analysis indicates that earlier correlations of droplet size with specific entropy in the source were useful at best only for a fixed nozzle size.

  6. Experimental elaboration of liquid droplet cooler-radiator models under microgravity and deep vacuum conditions

    NASA Astrophysics Data System (ADS)

    Koroteev, A. A.; Nagel, Yu. A.; Filatov, N. I.

    2015-12-01

    The basic results of space tests of liquid droplet cooler-radiator models as the main elements of frameless systems for low-grade heat rejection are considered. The studies carried out have been analyzed and intermediate elaboration's results are summarized, which concern (1) the development of generators of droplet propellant flows, (2) revealing an operational behavior of fluid collectors of various types and analysis of unsolved problems associated with droplet collection upon the open trajectory's section passage, and (3) provision of the coolant circulation contour's closing. The necessity is substantiated for the activization of works directed to carrying out space experiments with improved radiator models and new promising propellants in order to provide a possibility of creating new space power plants characterized by megawatt power levels.

  7. THE LIQUID AND GASEOUS FUEL DISTRIBUTION SYSTEM

    EPA Science Inventory

    The report describes the national liquid and gaseous fuel distribution system. he study leading to the report was performed as part of an effort to better understand emissions of volatile organic compounds from the fuel distribution system. he primary, secondary, and tertiary seg...

  8. Combustion of liquid fuels in diesel engine

    NASA Technical Reports Server (NTRS)

    Alt, Otto

    1924-01-01

    Hitherto, definite specifications have always been made for fuel oils and they have been classified as more or less good or non-utilizable. The present aim, however, is to build Diesel engines capable of using even the poorest liquid fuels and especially the waste products of the oil industry, without special chemical or physical preparation.

  9. Revisiting kinetic boundary conditions at the surface of fuel droplet hydrocarbons: An atomistic computational fluid dynamics simulation.

    PubMed

    Nasiri, Rasoul

    2016-01-01

    The role of boundary conditions at the interface for both Boltzmann equation and the set of Navier-Stokes equations have been suggested to be important for studying of multiphase flows such as evaporation/condensation process which doesn't always obey the equilibrium conditions. Here we present aspects of transition-state theory (TST) alongside with kinetic gas theory (KGT) relevant to the study of quasi-equilibrium interfacial phenomena and the equilibrium gas phase processes, respectively. A two-state mathematical model for long-chain hydrocarbons which have multi-structural specifications is introduced to clarify how kinetics and thermodynamics affect evaporation/condensation process at the surface of fuel droplet, liquid and gas phases and then show how experimental observations for a number of n-alkane may be reproduced using a hybrid framework TST and KGT with physically reasonable parameters controlling the interface, gas and liquid phases. The importance of internal activation dynamics at the surface of n-alkane droplets is established during the evaporation/condensation process. PMID:27215897

  10. Revisiting kinetic boundary conditions at the surface of fuel droplet hydrocarbons: An atomistic computational fluid dynamics simulation

    PubMed Central

    Nasiri, Rasoul

    2016-01-01

    The role of boundary conditions at the interface for both Boltzmann equation and the set of Navier-Stokes equations have been suggested to be important for studying of multiphase flows such as evaporation/condensation process which doesn’t always obey the equilibrium conditions. Here we present aspects of transition-state theory (TST) alongside with kinetic gas theory (KGT) relevant to the study of quasi-equilibrium interfacial phenomena and the equilibrium gas phase processes, respectively. A two-state mathematical model for long-chain hydrocarbons which have multi-structural specifications is introduced to clarify how kinetics and thermodynamics affect evaporation/condensation process at the surface of fuel droplet, liquid and gas phases and then show how experimental observations for a number of n-alkane may be reproduced using a hybrid framework TST and KGT with physically reasonable parameters controlling the interface, gas and liquid phases. The importance of internal activation dynamics at the surface of n-alkane droplets is established during the evaporation/condensation process. PMID:27215897

  11. Revisiting kinetic boundary conditions at the surface of fuel droplet hydrocarbons: An atomistic computational fluid dynamics simulation

    NASA Astrophysics Data System (ADS)

    Nasiri, Rasoul

    2016-05-01

    The role of boundary conditions at the interface for both Boltzmann equation and the set of Navier-Stokes equations have been suggested to be important for studying of multiphase flows such as evaporation/condensation process which doesn’t always obey the equilibrium conditions. Here we present aspects of transition-state theory (TST) alongside with kinetic gas theory (KGT) relevant to the study of quasi-equilibrium interfacial phenomena and the equilibrium gas phase processes, respectively. A two-state mathematical model for long-chain hydrocarbons which have multi-structural specifications is introduced to clarify how kinetics and thermodynamics affect evaporation/condensation process at the surface of fuel droplet, liquid and gas phases and then show how experimental observations for a number of n-alkane may be reproduced using a hybrid framework TST and KGT with physically reasonable parameters controlling the interface, gas and liquid phases. The importance of internal activation dynamics at the surface of n-alkane droplets is established during the evaporation/condensation process.

  12. Probing Ion Transfer across Liquid-Liquid Interfaces by Monitoring Collisions of Single Femtoliter Oil Droplets on Ultramicroelectrodes.

    PubMed

    Deng, Haiqiang; Dick, Jeffrey E; Kummer, Sina; Kragl, Udo; Strauss, Steven H; Bard, Allen J

    2016-08-01

    We describe a method of observing collisions of single femtoliter (fL) oil (i.e., toluene) droplets that are dispersed in water on an ultramicroelectrode (UME) to probe the ion transfer across the oil/water interface. The oil-in-water emulsion was stabilized by an ionic liquid, in which the oil droplet trapped a highly hydrophobic redox probe, rubrene. The ionic liquid also functions as the supporting electrolyte in toluene. When the potential of the UME was biased such that rubrene oxidation would be possible when a droplet collided with the electrode, no current spikes were observed. This implies that the rubrene radical cation is not hydrophilic enough to transfer into the aqueous phase. We show that current spikes are observed when tetrabutylammonium trifluoromethanesulfonate or tetrahexylammonium hexafluorophosphate are introduced into the toluene phase and when tetrabutylammonium perchlorate is introduced into the water phase, implying that the ion transfer facilitates electron transfer in the droplet collisions. The current (i)-time (t) behavior was evaluated quantitatively, which indicated the ion transfer is fast and reversible. Furthermore, the size of these emulsion droplets can also be calculated from the electrochemical collision. We further investigated the potential dependence on the electrochemical collision response in the presence of tetrabutylammonium trifluoromethanesulfonate in toluene to obtain the formal ion transfer potential of tetrabutylammonium across the toluene/water interface, which was determined to be 0.754 V in the inner potential scale. The results yield new physical insights into the charge balance mechanism in emulsion droplet collisions and indicate that the electrochemical collision technique can be used to probe formal ion transfer potentials between water and solvents with very low (ε < 5) dielectric constants. PMID:27387789

  13. Supersaturation and diffusional droplet growth in liquid clouds: Polydisperse spectra

    NASA Astrophysics Data System (ADS)

    Pinsky, M.; Mazin, I. P.; Korolev, A.; Khain, A.

    2014-11-01

    Evolution of droplet size distribution (DSD) due to the water vapor diffusion in a vertically moving adiabatic parcels is investigated. Analytical expressions for height dependences of the main DSD parameters and DSD moments are obtained. The asymptotic behavior of the DSD parameters at large heights above cloud base is determined. It is shown that during diffusion growth, the width and the relative dispersion of the DSD decrease with height as z- 1/3 and z- 2/3, respectively. The paper presents examples of DSD evolution in cases DSD forms on aerosols with a three-mode lognormal distribution. The aerosol distribution parameters used in the study correspond to four aerosol types: "Marine," "Clean continental," "Background," and extremely polluted "Urban." The vertical profiles of DSD parameters are compared with the asymptotic profiles. It is shown that in case of polydisperse DSD evolution, the vertical profile of supersaturation within several hundred meters above the cloud base can be approximated by a supersaturation profile corresponding to the "equivalent" monodisperse DSD. The initial radius of this equivalent DSD is equal to the mean radius of polydisperse DSD (haze size distribution) at cloud base, which is estimated using the Kohler theory. This result of the relation between the polydisperse and monodisperse solutions is universal. A new equation for estimation of supersaturation maximum for polydisperse case is obtained. The obtained analytical expressions and numerical results are useful for understanding the mechanisms of DSD formation in clouds and for parameterization of warm microphysical processes in cloud models.

  14. Testing of detector papers with CW liquid-agent droplets of known diameter. Droplets generator, calibration, and procedures. Technical note

    SciTech Connect

    Thoraval, D.; Bovenkamp, J.W.; Bets, R.W.; Preston, J.M.; Hart, L.G.

    1986-01-01

    The droplet generator used at DREO to test the color-producing ability of detector papers with CW-agent droplets of known diameter is described. The calibration of the equipment, the droplet size consistency and the procedure used to test the CW-agent-detector papers are discussed.

  15. Shapes of a liquid droplet in a periodic box

    NASA Astrophysics Data System (ADS)

    Prestipino, Santi; Caccamo, Carlo; Costa, Dino; Malescio, Gianpietro; Munaò, Gianmarco

    2015-08-01

    Within the coexistence region between liquid and vapor the equilibrium pressure of a simulated fluid exhibits characteristic jumps and plateaus when plotted as a function of density at constant temperature. These features exclusively pertain to a finite-size sample in a periodic box, as they are washed out in the bulk limit. Below the critical density, at each pressure jump the shape of the liquid drop undergoes a morphological transition, changing from spherical to cylindrical to slablike as the density is increased. We formulate a simple theory of these shape transitions, which is adapted from a calculation originally developed by Binder and coworkers [L. G. MacDowell, P. Virnau, M. Muller, and K. Binder, J. Chem. Phys. 120, 5293 (2004), 10.1063/1.1645784]. Our focus is on the pressure equation of state (rather than on the chemical potential, as in the original work) and includes an extension to elongated boxes. Predictions based on this theory well agree with extensive Monte Carlo data for the cut-and-shifted Lennard-Jones fluid. We further discuss the thermodynamic stability of liquid drops with shapes other than the three mentioned above, like those found deep inside the liquid-vapor region in simulations starting from scratch. Our theory classifies these more elaborate shapes as metastable.

  16. Novel cryogenic sources for liquid droplet and solid filament beams

    NASA Astrophysics Data System (ADS)

    Grams, Michael P.

    Two novel atomic and molecular beam sources have been created and tested consisting first of a superfluid helium liquid jet, and secondly a solid filament of argon. The superfluid helium apparatus is the second of its kind in the world and uses a modified liquid helium cryostat to inject a cylindrical stream of superfluid helium into vacuum through glass capillary nozzles with diameters on the order of one micron created on-site at Arizona State University. The superfluid beam is an entirely new way to study superfluid behavior, and has many new applications such as superfluid beam-surface scattering, beam-beam scattering, and boundary-free study of superfluidity. The solid beam of argon is another novel beam source created by flowing argon gas through a capillary 50 microns in diameter which is clamped by a small copper plate to a copper block kept at liquid nitrogen temperature. The gas subsequently cools and solidifies plugging the capillary. Upon heating, the solid plug melts and liquid argon exits the capillary and immediately freezes by evaporative cooling. The solid filaments may find application as wall-less cryogenic matrices, or targets for laser plasma sources of extreme UV and soft x-ray sources.

  17. Shapes of a liquid droplet in a periodic box.

    PubMed

    Prestipino, Santi; Caccamo, Carlo; Costa, Dino; Malescio, Gianpietro; Munaò, Gianmarco

    2015-08-01

    Within the coexistence region between liquid and vapor the equilibrium pressure of a simulated fluid exhibits characteristic jumps and plateaus when plotted as a function of density at constant temperature. These features exclusively pertain to a finite-size sample in a periodic box, as they are washed out in the bulk limit. Below the critical density, at each pressure jump the shape of the liquid drop undergoes a morphological transition, changing from spherical to cylindrical to slablike as the density is increased. We formulate a simple theory of these shape transitions, which is adapted from a calculation originally developed by Binder and coworkers [L. G. MacDowell, P. Virnau, M. Muller, and K. Binder, J. Chem. Phys. 120, 5293 (2004)]. Our focus is on the pressure equation of state (rather than on the chemical potential, as in the original work) and includes an extension to elongated boxes. Predictions based on this theory well agree with extensive Monte Carlo data for the cut-and-shifted Lennard-Jones fluid. We further discuss the thermodynamic stability of liquid drops with shapes other than the three mentioned above, like those found deep inside the liquid-vapor region in simulations starting from scratch. Our theory classifies these more elaborate shapes as metastable. PMID:26382377

  18. Studying gas-sheared liquid film in horizontal rectangular duct with LIF technique: droplets deposition and bubbles entrapment

    NASA Astrophysics Data System (ADS)

    Cherdantsev, Andrey; Hann, David; Azzopardi, Barry

    2014-11-01

    High-speed laser-induced fluorescence technique is applied to study gas-sheared liquid film in horizontal rectangular duct (width 161 mm). Instantaneous distributions of film thickness over an area of 50*20 mm are obtained with frequency 10 kHz and spatial resolution 40 μm. The technique is also able to detect droplets entrained from film surface and gas bubbles entrapped by the liquid film. We focus on deposition of droplets onto film surface and dynamics of bubbles. Three scenarios of droplet impact are observed: 1) formation of a cavern, which is similar to well-known process of normal droplet impact onto still liquid surface; 2) ``ploughing,'' when droplet is sinking over long distance; 3) ``bouncing,'' when droplet survives the impact. The first scenario is often accompanied by entrainment of secondary droplets; the second by entrapment of air bubbles. Numerous impact events are quantitatively analyzed. Parameters of the impacting droplet, the film surface before the impact, the evolution of surface perturbation due to impact and the outcome of the impact (droplets or bubbles) are measured. Space-time trajectories of individual bubbles have also been obtained, including velocity, size and concentration inside the disturbance waves and in the base film region. EPSRC Programme Grant, MEMPHIS, EP/K0039761/1.

  19. On droplet combustion of biodiesel fuel mixed with diesel/alkanes in microgravity condition

    SciTech Connect

    Pan, Kuo-Long; Li, Je-Wei; Chen, Chien-Pei; Wang, Ching-Hua

    2009-10-15

    The burning characteristics of a biodiesel droplet mixed with diesel or alkanes such as dodecane and hexadecane were experimentally studied in a reduced-gravity environment so as to create a spherically symmetrical flame without the influence of natural convection due to buoyancy. Small droplets on the order of 500 {mu}m in diameter were initially injected via a piezoelectric technique onto the cross point intersected by two thin carbon fibers; these were prepared inside a combustion chamber that was housed in a drag shield, which was freely dropped onto a foam cushion. It was found that, for single component droplets, the tendency to form a rigid soot shell was relatively small for biodiesel fuel as compared to that exhibited by the other tested fuels. The soot created drifted away readily, showing a puffing phenomenon; this could be related to the distinct molecular structure of biodiesel leading to unique soot layers that were more vulnerable to oxidative reactivity as compared to the soot generated by diesel or alkanes. The addition of biodiesel to these more traditional fuels also presented better performance with respect to annihilating the soot shell, particularly for diesel. The burning rate generally follows that of multi-component fuels, by some means in terms of a lever rule, whereas the mixture of biodiesel and dodecane exhibits a somewhat nonlinear relation with the added fraction of dodecane. This might be related to the formation of a soot shell. (author)

  20. An Oil-Stream Photomicrographic Aeroscope for Obtaining Cloud Liquid-Water Content and Droplet Size Distributions in Flight

    NASA Technical Reports Server (NTRS)

    Hacker, Paul T.

    1956-01-01

    An airborne cloud aeroscope by which droplet size, size distribution, and liquid-water content of clouds can be determined has been developed and tested in flight and in wind tunnels with water sprays. In this aeroscope the cloud droplets are continuously captured in a stream of oil, which Is then photographed by a photomicrographic camera. The droplet size and size distribution can be determined directly from the photographs. With the droplet size distribution known, the liquid-water content of the cloud can be computed from the geometry of the aeroscope, the airspeed, and the oil-flow rate. The aeroscope has the following features: Data are obtained semi-automatically, and permanent data are taken in the form of photographs. A single picture usually contains a sufficient number of droplets to establish the droplet size distribution. Cloud droplets are continuously captured in the stream of oil, but pictures are taken at Intervals. The aeroscope can be operated in icing and non-icing conditions. Because of mixing of oil in the instrument, the droplet-distribution patterns and liquid-water content values from a single picture are exponentially weighted average values over a path length of about 3/4 mile at 150 miles per hour. The liquid-water contents, volume-median diameters, and distribution patterns obtained on test flights and in the Lewis icing tunnel are similar to previously published data.

  1. Global survey of the relationships of cloud albedo and liquid water path with droplet size using ISCCP

    SciTech Connect

    Han, Q.; Chou, J.; Welch, R.M.; Rossow, W.B.

    1998-07-01

    The most common approach used to model the aerosol indirect effect on clouds holds the cloud liquid water path constant. In this case, increasing aerosol concentration increases cloud droplet concentration, decreases cloud droplet size, and increases cloud albedo. The expected decrease in cloud droplet size associated with larger aerosol concentrations has been found to be larger over land than over water and larger in the Northern that in the Southern Hemisphere, but the corresponding cloud albedo increase has not been found. Many previous studies have shown that cloud liquid water path varies with changing cloud droplet size, which may alter the behavior of clouds when aerosols change. This study examines the relationship between geographic and seasonal variations of cloud effective droplet size and cloud albedo, as well as cloud liquid water path, in low-level clouds using International Satellite Cloud Climatology Project data. The results show that cloud albedo increases with decreasing droplet size for most clouds over continental areas and for all optically thicker clouds, but that cloud albedo decreases with decreasing droplet size for optically thinner clouds over most oceans and the tropical rain forest regions. For almost all clouds, the liquid water path increases with increasing cloud droplet size.

  2. Shape evolution of a single liquid-crystal droplet immersed in an isotropic matrix under transient and steady flow

    NASA Astrophysics Data System (ADS)

    Wu, Youjun; Yu, Wei; Zhou, Chixing; Xu, Yuanze

    2007-04-01

    The morphology evolution of immiscible polymer-liquid crystal systems is quite different from flexible polymer-polymer mixtures due to the anisotropic properties of liquid crystals. The deformation and retraction of a single low molar mass liquid crystal 4' -pentyl-4-biphenylcarbonitrile (5CB) droplet and 4' -octyl-4-biphenylcarbonitrile (8CB) dispersed in polydimethyl-siloxane under two-dimensional linear flow was investigated by a computer-controlled four-roll mill, which is equipped with an optical microscope and a digital camera. The deformation parameter and orientation angle during deformation versus capillary number was obtained and compared with calculations using the Maffettone-Minale (MM) model and the Yu-Zhou liquid-crystal (YZ-LC) model. The MM model can describe the behavior of a Newtonian droplet in another Newtonian matrix whereas the YZ-LC model can describe the behavior of a LC droplet in a Newtonian matrix. The results showed that the deformation and rotation of a LC droplet is more difficult than viscoelastic droplets, possibly because of the resistance of the nematic elastic energy induced by the nematic mesogens deformation and orientation under flow field. Furthermore, the different behavior between flow-aligning 5CB and flow-tumbling 8CB droplets and the influence of droplet size of LC on deformation and retraction were discussed by experiment and calculation; the results reveal that the different size LC droplets show different evolution curves.

  3. High-Voltage Droplet Dispenser

    NASA Technical Reports Server (NTRS)

    Eichenberg, Dennis J.

    2003-01-01

    An apparatus that is extremely effective in dispensing a wide range of droplets has been developed. This droplet dispenser is unique in that it utilizes a droplet bias voltage, as well as an ionization pulse, to release a droplet. Apparatuses that deploy individual droplets have been used in many applications, including, notably, study of combustion of liquid fuels. Experiments on isolated droplets are useful in that they enable the study of droplet phenomena under well-controlled and simplified conditions. In this apparatus, a syringe dispenses a known value of liquid, which emerges from, and hangs onto, the outer end of a flat-tipped, stainless steel needle. Somewhat below the needle tip and droplet is a ring electrode. A bias high voltage, followed by a high-voltage pulse, is applied so as to attract the droplet sufficiently to pull it off the needle. The voltages are such that the droplet and needle are negatively charged and the ring electrode is positively charged.

  4. Droplet vaporization in supercritical pressure environments

    NASA Astrophysics Data System (ADS)

    Farrell, Patrick V.; Peters, Bruce D.

    For most liquid-fueled combustion systems the behavior of the fuel as it is introduced to the combustion zone, often by spray injection, will have a significant impact on combustion. The subsequent combustion may be affected to a considerable degree by the initial spread of the liquid, break-up of larger fuel sheets and droplets into droplets of various sizes, droplet vaporization, and diffusion of gaseous fuel. Among the many factors which affect spray break-up and droplet vaporization are the environmental conditions into which the spray is introduced. For both diesel engines and rockets the environment pressure and temperature may be above the critical pressure and temperature of the injected fuel. In a compression-ignition internal combustion engine, the environment consists primarily of air, at pressures from 20 to 100 atmospheres and temperatures ranging from 900 to 1500 K. Even higher pressures are encountered in turbocharged diesels. A typical diesel reference fuel, dodecane, has a thermodynamic critical pressure of about 17 atmospheres, and a critical temperature of 600 K. Fuel is injected into a diesel engine environment in which ambient pressures exceed the critical pressure. While droplet temperatures are subcritical at first, they may rise to the critical temperature or higher. This paper will survey current understanding of supercritical pressure droplet vaporization. Specifically, the topics covered will include: liquid phase behavior; vapor phase behavior; thermodynamic and transport properties; droplet distribution and break-up; micro-explosions; and effects of microgravity.

  5. Combustion performance of bipropellant liquid rocket engine combustors with fuel-impingement cooling

    SciTech Connect

    Jiang, T.L.; Chiang, W.; Jang, S.

    1995-05-01

    In order to obtain an accurate combustion analyses which are important in the thruster design of modern advanced liquid rocket engine, flow analysis should be conducted from the injector phase down to the propulsive nozzle throat. Thus, in the present study, flow analysis for the axisymmetric thrust chamber of an OMV(exp 3) installed with a pintle-type ring-shaped injector and a conical convergent nozzle is conducted. Liquid monomethyl hydrazine (MMH) and nitrogen tetroxide (NTO) storable bipropellants are used as fuel and oxidizer sources. An optimum injected fuel and oxidizer droplet-size combination is proposed. Finally, the results obtained are presented. 4 refs.

  6. Combustion performance of bipropellant liquid rocket engine combustors with fuel-impingement cooling

    NASA Astrophysics Data System (ADS)

    Jiang, Tsung Leo; Chiang, Wei-Tang; Jang, Shyh-Dihng

    1995-05-01

    In order to obtain an accurate combustion analyses which are important in the thruster design of modern advanced liquid rocket engine, flow analysis should be conducted from the injector phase down to the propulsive nozzle throat. Thus, in the present study, flow analysis for the axisymmetric thrust chamber of an OMV(exp 3) installed with a pintle-type ring-shaped injector and a conical convergent nozzle is conducted. Liquid monomethyl hydrazine (MMH) and nitrogen tetroxide (NTO) storable bipropellants are used as fuel and oxidizer sources. An optimum injected fuel and oxidizer droplet-size combination is proposed. Finally, the results obtained are presented.

  7. Superheated fuel injection for combustion of liquid-solid slurries

    DOEpatents

    Robben, F.A.

    1984-10-19

    A method and device are claimed for obtaining, upon injection, flash evaporation of a liquid in a slurry fuel to aid in ignition and combustion. The device is particularly beneficial for use of coal-water slurry fuels in internal combustion engines such as diesel engines and gas turbines, and in external combustion devices such as boilers and furnaces. The slurry fuel is heated under pressure to near critical temperature in an injector accumulator, where the pressure is sufficiently high to prevent boiling. After injection into a combustion chamber, the water temperature will be well above boiling point at a reduced pressure in the combustion chamber, and flash boiling will preferentially take place at solid-liquid surfaces, resulting in the shattering of water droplets and the subsequent separation of the water from coal particles. This prevents the agglomeration of the coal particles during the subsequent ignition and combustion process, and reduces the energy required to evaporate the water and to heat the coal particles to ignition temperature. The overall effect will be to accelerate the ignition and combustion rates, and to reduce the size of the ash particles formed from the coal. 2 figs., 2 tabs.

  8. Superheated fuel injection for combustion of liquid-solid slurries

    DOEpatents

    Robben, Franklin A.

    1985-01-01

    A method and device for obtaining, upon injection, flash evaporation of a liquid in a slurry fuel to aid in ignition and combustion. The device is particularly beneficial for use of coal-water slurry fuels in internal combustion engines such as diesel engines and gas turbines, and in external combustion devices such as boilers and furnaces. The slurry fuel is heated under pressure to near critical temperature in an injector accumulator, where the pressure is sufficiently high to prevent boiling. After injection into a combustion chamber, the water temperature will be well above boiling point at a reduced pressure in the combustion chamber, and flash boiling will preferentially take place at solid-liquid surfaces, resulting in the shattering of water droplets and the subsequent separation of the water from coal particles. This prevents the agglomeration of the coal particles during the subsequent ignition and combustion process, and reduces the energy required to evaporate the water and to heat the coal particles to ignition temperature. The overall effect will be to accelerate the ignition and combustion rates, and to reduce the size of the ash particles formed from the coal.

  9. Supercritical microgravity droplet vaporization

    NASA Technical Reports Server (NTRS)

    Hartfield, J.; Curtis, E.; Farrell, P.

    1990-01-01

    Supercritical droplet vaporization is an important issue in many combustion systems, such as liquid fueled rockets and compression-ignition (diesel) engines. In order to study the details of droplet behavior at these conditions, an experiment was designed to provide a gas phase environment which is above the critical pressure and critical temperature of a single liquid droplet. In general, the droplet begins as a cold droplet in the hot, high pressure environment. In order to eliminate disruptions to the droplet by convective motion in the gas, forced and natural convection gas motion are required to be small. Implementation of this requirement for forced convection is straightforward, while reduction of natural convection is achieved by reduction in the g-level for the experiment. The resulting experiment consists of a rig which can stably position a droplet without restraint in a high-pressure, high temperature gas field in microgravity. The microgravity field is currently achieved by dropping the device in the NASA Lewis 2.2 second drop tower. The performance of the experimental device and results to date are presented.

  10. Direct-contact condensation on liquid droplets during rapid depressurization part 1

    SciTech Connect

    Pasamehmetoglu, K.O.; Nelson, R.A.

    1987-01-01

    In this paper, direct-contact condensation on liquid droplets during a rapid depressurization, which yields a sudden decrease in the saturation temperature, is investigated. The decrease in the saturation temperature may stem either from direct-contact condensation, which is referred to as condensation-induced depressurization, or from an accidental leakage from the system, which is referred to as system depressurization. The governing equations of the direct-contact condensation on liquid droplets injected into a steam chamber are obtained based upon some simplifying assumptions. Because of the induced nature of the depressurization, the condensation rates and the depressurization rates form a coupled set of equations that must be solved simultaneously. A forward-marching finite-difference scheme is used to obtain the simultaneous solution. Only sample results for the quasi-steady solution are reported within this paper. The limitations and the errors associated with such a solution are also discussed.

  11. Determination of droplet contours in liquid-liquid flows within microchannels

    NASA Astrophysics Data System (ADS)

    Pulvirenti, B.; Rostami, B.; Puccetti, G.; Morini, G. L.

    2015-11-01

    An experimental analysis of the droplet regime with a silicone oil-water two-phase flow within a micro cross-junction, varying the average velocity of the fluids, has been carried out. The micro cross-junction is made as intersection of two glass microchannels with a stadium-shaped cross-section with height H=190 μm and width Wj=195 μm within the junction and W=390 μm before and after the junction. The water flow rate is broken in droplets having spherical shape with dimensions and velocity that depend on the average velocity ratio imposed. Different kinds of intermittent droplets have been observed, in the ranges of average velocity (0.0105-0.042) m/s and (0.0004-0.0050) m/s for oil and water, respectively. The droplet velocity has been calculated starting from the detection of the shape of the droplets and then by the evaluation of the displacement of the droplets in the unit of time. The images of the droplets have been obtained from a high-speed camera, connected to an inverted microscope. The procedure of water phase contour detection is based on Matlab Image Toolbox scripts.

  12. Final optics protection in laser inertial fusion with cryogenic liquid droplets

    SciTech Connect

    Moir, R W

    2000-08-31

    A burst of x rays and vaporized debris from high yield targets can damage the final optics in laser inertial fusion energy (IFE) power plants and in laboratory experimental facilities such as the National Ignition Facility (NIF) or Laser MegaJoule (LMJ). Noble gases such as Xe or Kr have been proposed to protect final optics from target-produced x rays and debris. Some problems with the use of such ambient gas fills are the large amount of gas involved, heat transfer to a cryogenic target, potential resonant reradiation of x rays absorbed, and a nonuniform index of refraction due to turbulence interfering with the focusing of laser light. Also the fast igniter laser intensity may be too great for propagation through an ambient gas. We propose to provide the gas in the form of many small closely spaced liquid droplets injected in front of the optics. In the case of NIF, the droplets would be injected only when needed just before a high yield shot. The laser light that is absorbed will cause evaporation of the liquid and spreading of this gas. The liquid droplets intercept only {approx}5% of the laser light allowing {approx}95% to pass through to the target. The light absorbed in the NIF example (assumed to be 50% of the intercepted light, whose intensity is 3.6 x 10{sup 9} W/cm{sup 2}) would cause the xenon droplets to evaporate and spread uniformly such that the x rays from 10 eV to 2 keV are appreciably attenuated when they arrive 40 to 70 ns later at the optical surface. X rays above 3 keV and below 10 eV are not attenuated very much but their intensities are rapidly falling off in this range anyway. Typical droplet sizes are {approx}10 {micro}m radius with a spacing of {approx}0.4 mm. The gas would also protect vaporized target debris from condensing on the optics due to the 0.2 mg/cm{sup 2} of xenon (5 x 10{sup 17} cm{sup -2} or 8 Torr-cm for l-e-folding of 1 keV x-rays). These droplets might be produced with technology similar to ink jet technology and photo

  13. Injector for liquid fueled rocket engine

    NASA Technical Reports Server (NTRS)

    Cornelius, Charles S. (Inventor); Myers, W. Neill (Inventor); Shadoan, Michael David (Inventor); Sparks, David L. (Inventor)

    2000-01-01

    An injector for liquid fueled rocket engines wherein a generally flat core having a frustoconical dome attached to one side of the core to serve as a manifold for a first liquid, with the core having a generally circular configuration having an axis. The other side of the core has a plurality of concentric annular first slots and a plurality of annular concentric second slots alternating with the first slots, the second slots having a greater depth than said first slots. A bore extends through the core for inletting a second liquid into said core, the bore intersecting the second slots to feed the second liquid into the second slots. The core also has a plurality of first passageways leading from the manifold to the first annular slots for feeding the first liquid into said first slots. A faceplate brazed to said other side of the core is provided with apertures extending from the first and second slots through said face plate, these apertures being positioned to direct fuel and liquid oxygen into contact with each other in the combustion chamber. The first liquid may be liquid oxygen and the second liquid may be kerosene or liquid hydrogen.

  14. Size determination of mixed liquid and frozen water droplets using interferometric out-of-focus imaging

    NASA Astrophysics Data System (ADS)

    Jacquot Kielar, Justin; Wu, Yingchun; Coëtmellec, Sébastien; Lebrun, Denis; Gréhan, Gérard; Brunel, Marc

    2016-07-01

    We record simultaneously interferometric out-of-focus images and digital in-line holograms of liquid and frozen water droplets. We show that the analysis of speckle-like out-of-focus images allows a quantitative estimation of the size of the particles which is corroborated by numerical reconstruction of holograms recorded simultaneously. Interferometric out-of-focus imaging could be extended to the characterization of ice in clouds in the atmosphere.

  15. Droplet Burns in the Fiber-Supported Droplet Combustion Experiment

    NASA Technical Reports Server (NTRS)

    2003-01-01

    A fuel droplet burns in the Fiber-Supported Droplet Combustion (FSDC) Experiment on STS-94, July 4 1997, MET:02/19:20 (approximate). This experiment, performed in the Middeck Glovebox, allows us to study the burning of fuels such as n-heptane, n-decane, methanol, ethanol, methanol/water mixtures, and heptane/hexadecane mixtures in droplets as large as 6 mm (nearly 1/4 inch). In this sequence, you see the burn of a 5mm droplet of n-heptane, in a 30% O2/He environment at 1 atmosphere pressure. The droplet (looking bright pink because of reflected light) hangs suspended from the supporting fiber. FSDC-2 studied fundamental phenomena related to liquid fuel droplet combustion in air. Pure fuels and mixtures of fuels were burned as isolated single and dual droplets with and without forced air convection. The FSDC guest investigator was Forman Williams, University of California, San Diego. The experiment was part of the space research investigations conducted during the Microgravity Science Laboratory-1R mission (STS-94, July 1-17 1997). Advanced combustion experiments will be a part of investigations plarned for the International Space Station. (279KB JPEG, 1350 x 2026 pixels; downlinked video, higher quality not available) The MPG from which this composite was made is available at http://mix.msfc.nasa.gov/ABSTRACTS/MSFC-0300175.html.

  16. Acoustic levitator for structure measurements on low temperature liquid droplets.

    PubMed

    Weber, J K R; Rey, C A; Neuefeind, J; Benmore, C J

    2009-08-01

    A single-axis acoustic levitator was constructed and used to levitate liquid and solid drops of 1-3 mm in diameter at temperatures in the range -40 to +40 degrees C. The levitator comprised (i) two acoustic transducers mounted on a rigid vertical support that was bolted to an optical breadboard, (ii) an acoustic power supply that controlled acoustic intensity, relative phase of the drive to the transducers, and could modulate the acoustic forces at frequencies up to 1 kHz, (iii) a video camera, and (iv) a system for providing a stream of controlled temperature gas flow over the sample. The acoustic transducers were operated at their resonant frequency of approximately 22 kHz and could produce sound pressure levels of up to 160 dB. The force applied by the acoustic field could be modulated to excite oscillations in the sample. Sample temperature was controlled using a modified Cryostream Plus and measured using thermocouples and an infrared thermal imager. The levitator was installed at x-ray beamline 11 ID-C at the Advanced Photon Source and used to investigate the structure of supercooled liquids.

  17. Acoustic levitator for structure measurements on low temperature liquid droplets.

    PubMed

    Weber, J K R; Rey, C A; Neuefeind, J; Benmore, C J

    2009-08-01

    A single-axis acoustic levitator was constructed and used to levitate liquid and solid drops of 1-3 mm in diameter at temperatures in the range -40 to +40 degrees C. The levitator comprised (i) two acoustic transducers mounted on a rigid vertical support that was bolted to an optical breadboard, (ii) an acoustic power supply that controlled acoustic intensity, relative phase of the drive to the transducers, and could modulate the acoustic forces at frequencies up to 1 kHz, (iii) a video camera, and (iv) a system for providing a stream of controlled temperature gas flow over the sample. The acoustic transducers were operated at their resonant frequency of approximately 22 kHz and could produce sound pressure levels of up to 160 dB. The force applied by the acoustic field could be modulated to excite oscillations in the sample. Sample temperature was controlled using a modified Cryostream Plus and measured using thermocouples and an infrared thermal imager. The levitator was installed at x-ray beamline 11 ID-C at the Advanced Photon Source and used to investigate the structure of supercooled liquids. PMID:19725664

  18. Organized Assemblies of Colloids Formed at the Poles of Micrometer-Sized Droplets of Liquid Crystal

    PubMed Central

    Wang, Xiaoguang; Miller, Daniel S.; de Pablo, Juan J.

    2014-01-01

    We report on the formation of organized assemblies of 1 μm-in-diameter colloids (polystyrene (PS)) at the poles of water-dispersed droplets (diameters 7 - 20 μm) of nematic liquid crystal (LC). For 4-cyano-4′-pentylbiphenyl droplets decorated with two to five PS colloids, we found 32 distinct arrangements of the colloids to form at the boojums of bipolar droplet configurations. Significantly, all but one of these configurations (a ring comprised of five PS colloids) could be mapped onto a local (non-close packed) hexagonal lattice. To provide insight into the origin of the hexagonal lattice, we investigated planar aqueous—LC interfaces, and found that organized assemblies of PS colloids did not form at these interfaces. Experiments involving the addition of salts revealed that a repulsive interaction of electrostatic origin prevented formation of assemblies at planar interfaces, and that regions of high splay near the poles of the LC droplets generated cohesive interactions between colloids that could overcome the repulsion. Support for this interpretation was obtained from a model that included (i) a long-range attraction between adsorbed colloids and the boojum due to the increasing rate of strain (splay) of LC near the boojum (splay attraction), (ii) an attractive inter-colloid interaction that reflects the quadrupolar symmetry of the strain in the LC around the colloids, and (iii) electrostatic repulsion between colloids. The model predicts that electrostatic repulsion between colloids can lead to a ∼1,000 kBT energy barrier at planar interfaces of LC films, and that the repulsive interaction can be overcome by splay attraction of the colloids to the boojums of the LC droplets. Overall, the results reported in this paper advance our understanding of the directed assembly of colloids at interfaces of LC droplets. PMID:25284139

  19. Organosiloxane working fluids for the liquid droplet radiator

    NASA Technical Reports Server (NTRS)

    Buch, R. R.; Huntress, A. R.

    1985-01-01

    Siloxane-based working fluids for advanced space radiators requiring direct fluid exposure to the space environment are evaluated. Isolation of five candidate fluids by vacuum distillation from existing siloxane polymers is discussed. The five fluids recovered include a polydimethylsiloxane, three phenyl-containing siloxanes, and a methylhexylsiloxane. Vapor pressures and viscosities for the five fluids are reported over the temperature range of 250 to 400 K. Use of thermal-gravimetric analysis to reliably estimate vapor pressures of 10 to the -8 power Pascals is described. Polydimethylsiloxane (PDMS) and polymethylphenylsiloxane (PMPS) are selected from the five candidate fluids based on favorable vapor pressure and viscosity, as well as perceived stability in low-Earth orbit environments. Characterization of these fluids by infrared spectroscopy, Si-29 NMR, gel-permeation chromatography, and liquid chromatography is presented. Both fluids consist of narrow molecular weight distributions, with average molecular weights of about 2500 for PDMS and 1300 for PMPS.

  20. Three-dimensional analysis of thermo-mechanically rotating cholesteric liquid crystal droplets under a temperature gradient

    NASA Astrophysics Data System (ADS)

    Yamamoto, T.; Kuroda, M.; Sano, M.

    2015-02-01

    We studied the rotational motion of cholesteric liquid crystal droplets under a temperature gradient (the Lehmann effect). We found that different surface treatments, planar and homeotropic anchoring, provided three types of droplets with different textures and geometries. The rotational velocity of these droplets depends differently on their size. Determining the three-dimensional structures of these droplets by the fluorescence confocal polarizing microscopy, we propose a phenomenological equation to explain the rotational behavior of these droplets. This result shows that the description by the Ericksen-Leslie theory should be valid in the bulk of the droplet, but we need to take into account the surface torque induced by temperature gradient to fully understand the Lehmann effect.

  1. Packaging a liquid metal ESD with micro-scale Mercury droplet.

    SciTech Connect

    Barnard, Casey Anderson

    2011-08-01

    A liquid metal ESD is being developed to provide electrical switching at different acceleration levels. The metal will act as both proof mass and electric contact. Mercury is chosen to comply with operation parameters. There are many challenges surrounding the deposition and containment of micro scale mercury droplets. Novel methods of micro liquid transfer are developed to deliver controllable amounts of mercury to the appropriate channels in volumes under 1 uL. Issues of hermetic sealing and avoidance of mercury contamination are also addressed.

  2. POWER GENERATION FROM LIQUID METAL NUCLEAR FUEL

    DOEpatents

    Dwyer, O.E.

    1958-12-23

    A nuclear reactor system is described wherein the reactor is the type using a liquid metal fuel, such as a dispersion of fissile material in bismuth. The reactor is designed ln the form of a closed loop having a core sectlon and heat exchanger sections. The liquid fuel is clrculated through the loop undergoing flssion in the core section to produce heat energy and transferrlng this heat energy to secondary fluids in the heat exchanger sections. The fission in the core may be produced by a separate neutron source or by a selfsustained chain reaction of the liquid fuel present in the core section. Additional auxiliary heat exchangers are used in the system to convert water into steam which drives a turbine.

  3. Coupled Mechanisms of Precipitation and Atomization in Burning Nanofluid Fuel Droplets

    PubMed Central

    Miglani, Ankur; Basu, Saptarshi

    2015-01-01

    Understanding the combustion characteristics of fuel droplets laden with energetic nanoparticles (NP) is pivotal for lowering ignition delay, reducing pollutant emissions and increasing the combustion efficiency in next generation combustors. In this study, first we elucidate the feedback coupling between two key interacting mechanisms, namely, secondary atomization and particle agglomeration; that govern the effective mass fraction of NPs within the droplet. Second, we show how the initial NP concentration modulates their relative dominance leading to a master-slave configuration. Secondary atomization of novel nanofuels is a crucial process since it enables an effective transport of dispersed NPs to the flame (a pre-requisite condition for NPs to burn). Contrarily, NP agglomeration at the droplet surface leads to shell formation thereby retaining NPs inside the droplet. In particular, we show that at dense concentrations shell formation (master process) dominates over secondary atomization (slave) while at dilute particle loading it is the high frequency bubble ejections (master) that disrupt shell formation (slave) through its rupture and continuous outflux of NPs. This results in distinct combustion residues at dilute and dense concentrations, thereby providing a method of manufacturing flame synthesized microstructures with distinct morphologies. PMID:26446366

  4. Coupled Mechanisms of Precipitation and Atomization in Burning Nanofluid Fuel Droplets.

    PubMed

    Miglani, Ankur; Basu, Saptarshi

    2015-01-01

    Understanding the combustion characteristics of fuel droplets laden with energetic nanoparticles (NP) is pivotal for lowering ignition delay, reducing pollutant emissions and increasing the combustion efficiency in next generation combustors. In this study, first we elucidate the feedback coupling between two key interacting mechanisms, namely, secondary atomization and particle agglomeration; that govern the effective mass fraction of NPs within the droplet. Second, we show how the initial NP concentration modulates their relative dominance leading to a master-slave configuration. Secondary atomization of novel nanofuels is a crucial process since it enables an effective transport of dispersed NPs to the flame (a pre-requisite condition for NPs to burn). Contrarily, NP agglomeration at the droplet surface leads to shell formation thereby retaining NPs inside the droplet. In particular, we show that at dense concentrations shell formation (master process) dominates over secondary atomization (slave) while at dilute particle loading it is the high frequency bubble ejections (master) that disrupt shell formation (slave) through its rupture and continuous outflux of NPs. This results in distinct combustion residues at dilute and dense concentrations, thereby providing a method of manufacturing flame synthesized microstructures with distinct morphologies. PMID:26446366

  5. IR spectra of water droplets in no man's land and the location of the liquid-liquid critical point

    NASA Astrophysics Data System (ADS)

    Ni, Yicun; Skinner, J. L.

    2016-09-01

    No man's land is the region in the metastable phase diagram of water where it is very difficult to do experiments on liquid water because of homogeneous nucleation to the crystal. There are a number of estimates of the location in no man's land of the liquid-liquid critical point, if it exists. We suggest that published IR absorption experiments on water droplets in no man's land can provide information about the correct location. To this end, we calculate theoretical IR spectra for liquid water over a wide range of temperatures and pressures, using our E3B3 model, and use the results to argue that the temperature dependence of the experimental spectra is inconsistent with several of the estimated critical point locations, but consistent with others.

  6. Nuclear Energy and Synthetic Liquid Transportation Fuels

    NASA Astrophysics Data System (ADS)

    McDonald, Richard

    2012-10-01

    This talk will propose a plan to combine nuclear reactors with the Fischer-Tropsch (F-T) process to produce synthetic carbon-neutral liquid transportation fuels from sea water. These fuels can be formed from the hydrogen and carbon dioxide in sea water and will burn to water and carbon dioxide in a cycle powered by nuclear reactors. The F-T process was developed nearly 100 years ago as a method of synthesizing liquid fuels from coal. This process presently provides commercial liquid fuels in South Africa, Malaysia, and Qatar, mainly using natural gas as a feedstock. Nuclear energy can be used to separate water into hydrogen and oxygen as well as to extract carbon dioxide from sea water using ion exchange technology. The carbon dioxide and hydrogen react to form synthesis gas, the mixture needed at the beginning of the F-T process. Following further refining, the products, typically diesel and Jet-A, can use existing infrastructure and can power conventional engines with little or no modification. We can then use these carbon-neutral liquid fuels conveniently long into the future with few adverse environmental impacts.

  7. Liquid fuels production from biomass. Final report

    SciTech Connect

    Levy, P. F.; Sanderson, J. E.; Ashare, E.; Wise, D. L.; Molyneaux, M. S.

    1980-06-30

    The current program to convert biomass into liquid hydrocarbon fuels is an extension of a previous program to ferment marine algae to acetic acid. In that study it was found that marine algae could be converted to higher aliphatic organic acids and that these acids could be readily removed from the fermentation broth by membrane or liquid-liquid extraction. It was then proposed to convert these higher organic acids via Kolbe electrolysis to aliphatic hydrocarbons, which may be used as a diesel fuel. The specific goals for the current porgram are: (1) establish conditions under which substrates other than marine algae may be converted in good yield to organic acids, here the primary task is methane suppression; (2) modify the current 300-liter fixed packed bed batch fermenter to operate in a continuous mode; (3) change from membrane extraction of organic acids to liquid-liquid extraction; (4) optimize the energy balance of the electrolytic oxidation process, the primary task is to reduce the working potential required for the electrolysis while maintaining an adequate current density; (5) scale the entire process up to match the output of the 300 liter fermenter; and (6) design pilot plant and commercial size plant (1000 tons/day) processes for converting biomass to liquid hydrocarbon fuels and perform an economic analysis for the 1000 ton/day design.

  8. Chiral symmetry breaking and surface faceting in chromonic liquid crystal droplets with giant elastic anisotropy

    PubMed Central

    Jeong, Joonwoo; Davidson, Zoey S.; Collings, Peter J.; Lubensky, Tom C.; Yodh, A. G.

    2014-01-01

    Confined liquid crystals (LC) provide a unique platform for technological applications and for the study of LC properties, such as bulk elasticity, surface anchoring, and topological defects. In this work, lyotropic chromonic liquid crystals (LCLCs) are confined in spherical droplets, and their director configurations are investigated as a function of mesogen concentration using bright-field and polarized optical microscopy. Because of the unusually small twist elastic modulus of the nematic phase of LCLCs, droplets of this phase exhibit a twisted bipolar configuration with remarkably large chiral symmetry breaking. Further, the hexagonal ordering of columns and the resultant strong suppression of twist and splay but not bend deformation in the columnar phase, cause droplets of this phase to adopt a concentric director configuration around a central bend disclination line and, at sufficiently high mesogen concentration, to exhibit surface faceting. Observations of director configurations are consistent with Jones matrix calculations and are understood theoretically to be a result of the giant elastic anisotropy of LCLCs. PMID:24449880

  9. Coloring Rate of Phenolphthalein by Reaction with Alkaline Solution Observed by Liquid-Droplet Collision.

    PubMed

    Takano, Yuuka; Kikkawa, Shigenori; Suzuki, Tomoko; Kohno, Jun-ya

    2015-06-11

    Many important chemical reactions are induced by mixing two solutions. This paper presents a new way to measure rates of rapid chemical reactions induced by mixing two reactant solutions using a liquid-droplet collision. The coloring reaction of phenolphthalein (H2PP) by a reaction with NaOH is investigated kinetically. Liquid droplets of H2PP/ethanol and NaOH/H2O solutions are made to collide, which induces a reaction that transforms H2PP into a deprotonated form (PP(2-)). The concentration of PP(2-) is evaluated from the RGB values of pixels in the colored droplet images, and is measured as a function of the elapsed time from the collision. The obtained rate constant is (2.2 ± 0.7) × 10(3) M(-1) s(-1), which is the rate constant for the rate-determining step of the coloring reaction of H2PP. This method was shown to be applicable to determine rate constants of rapid chemical reactions between two solutions.

  10. Thermocapillary migration of liquid droplets in a temperature gradient in a density matched system

    NASA Astrophysics Data System (ADS)

    Rashidnia, N.; Balasubramaniam, R.

    1991-05-01

    An experimental investigation of thermocapillary flow in droplets of a vegetable oil (partially hydrogenated soybean oil) immersed in silicone oil was conducted in a test cell with a heated top wall and a cooled bottom wall. The liquids are nearly immiscible and have equal densities at a temperature below the room temperature, thus providing a simulation of low-gravity conditions by reducing the buoyancy forces. The interfacial tension between the two oils was measured in the temperature range 20 to 50 C using a capillary tube and (d sigma)/(d T) was determined to be negative. Droplets ranging in sizes from 3 mm to 1 cm diameter were injected into the silicone oil. The vertical temperature profile in the bulk liquid (silicone oil) produces temperature variations along the interface which induce variations in the interfacial tension. The flow inside the droplet driven by the resulting interfacial shear stresses was observed using a laser light-sheet flow visualization technique. The flow direction is consistent with the sign of (d sigma)/(d T). The observed maximum surface velocities are compared to the theoretical predictions of Young et al. (1959).

  11. Thermocapillary migration of liquid droplets in a temperature gradient in a density matched system

    NASA Astrophysics Data System (ADS)

    Rashidnia, N.; Balasubramaniam, R.

    1989-12-01

    An experimental investigation of thermocapillary flow in droplets of a vegetable oil (partially hydrogenated soybean oil) immersed in silicone oil was conducted in a test cell with a heated top wall and a cooled bottom wall. The liquids are nearly immiscible and have equal densities at a temperature below the room temperature, thus providing a simulation of low-gravity conditions by reducing the buoyancy forces. The interfacial tension between the two oils was measured in the temperature range 20 to 50 C using a capillary tube and (d sigma)/(d T) was determined to be negative. Droplets ranging in sizes from 3 mm to 1 cm diameter were injected into the silicone oil. The vertical temperature profile in the bulk liquid (silicone oil) produces temperature variations along the interface which induce variations in the interfacial tension. The flow inside the droplet driven by the resulting interfacial shear stresses was observed using a laser light-sheet flow visualization technique. The flow direction is consistent with the sign of (d sigma)/(d T). The observed maximum surface velocities are compared to the theoretical predictions of Young et al. (1959).

  12. Thermocapillary migration of liquid droplets in a temperature gradient in a density matched system

    NASA Technical Reports Server (NTRS)

    Rashidnia, N.; Balasubramaniam, R.

    1989-01-01

    An experimental investigation of thermocapillary flow in droplets of a vegetable oil (partially hydrogenated soybean oil) immersed in silicone oil was conducted in a test cell with a heated top wall and a cooled bottom wall. The liquids are nearly immiscible and have equal densities at a temperature below the room temperature, thus providing a simulation of low-gravity conditions by reducing the buoyancy forces. The interfacial tension between the two oils was measured in the temperature range 20 to 50 C using a capillary tube and (d sigma)/(d T) was determined to be negative. Droplets ranging in sizes from 3 mm to 1 cm diameter were injected into the silicone oil. The vertical temperature profile in the bulk liquid (silicone oil) produces temperature variations along the interface which induce variations in the interfacial tension. The flow inside the droplet driven by the resulting interfacial shear stresses was observed using a laser light-sheet flow visualization technique. The flow direction is consistent with the sign of (d sigma)/(d T). The observed maximum surface velocities are compared to the theoretical predictions of Young et al. (1959).

  13. Formation and Maturation of Phase-Separated Liquid Droplets by RNA-Binding Proteins.

    PubMed

    Lin, Yuan; Protter, David S W; Rosen, Michael K; Parker, Roy

    2015-10-15

    Eukaryotic cells possess numerous dynamic membrane-less organelles, RNP granules, enriched in RNA and RNA-binding proteins containing disordered regions. We demonstrate that the disordered regions of key RNP granule components and the full-length granule protein hnRNPA1 can phase separate in vitro, producing dynamic liquid droplets. Phase separation is promoted by low salt concentrations or RNA. Over time, the droplets mature to more stable states, as assessed by slowed fluorescence recovery after photobleaching and resistance to salt. Maturation often coincides with formation of fibrous structures. Different disordered domains can co-assemble into phase-separated droplets. These biophysical properties demonstrate a plausible mechanism by which interactions between disordered regions, coupled with RNA binding, could contribute to RNP granule assembly in vivo through promoting phase separation. Progression from dynamic liquids to stable fibers may be regulated to produce cellular structures with diverse physiochemical properties and functions. Misregulation could contribute to diseases involving aberrant RNA granules. PMID:26412307

  14. Spreading of liquid droplets on cylindrical surfaces: Accurate determination of contact angle

    NASA Astrophysics Data System (ADS)

    Wagner, H. D.

    1990-02-01

    The characterization of the physicochemical nature of interfaces is a key problem in the field of advanced fibrous composites. The macroscopic regime contact angle, which reflects the energetics of wetting at the solid-liquid interface, is difficult to measure by usual methods in the case of very thin cylindrical fibers, but it may be calculated from the shape of a liquid droplet spread onto a cylindrical monofilament using a method developed by Yamaki and Katayama [J. Appl. Polym. Sci. 19, 2897 (1975)], and B. J. Carroll [J. Coll. Interf. Sci. 57, 488 (1976)]. Unfortunately, measurements of the contact angle based on this method are, so far, unable to provide an accuracy of better than about 5°. In the present article two simple extensions of the method of Yamaki and Katayama and Carroll, are presented, from which highly accurate values of the contact angle may be obtained. This is demonstrated experimentally from the spreading of glycerol droplets on carbon fibers and epoxy droplets on aramid fibers.

  15. Thermocapillary migration of liquid droplets in a temperature gradient in a density matched system

    NASA Technical Reports Server (NTRS)

    Rashidnia, N.; Balasubramaniam, R.

    1991-01-01

    An experimental investigation of thermocapillary flow in droplets of a vegetable oil (partially hydrogenated soybean oil) immersed in silicone oil was conducted in a test cell with a heated top wall and a cooled bottom wall. The liquids are nearly immiscible and have equal densities at a temperature below the room temperature, thus providing a simulation of low-gravity conditions by reducing the buoyancy forces. The interfacial tension between the two oils was measured in the temperature range 20 to 50 C using a capillary tube and (d sigma)/(d T) was determined to be negative. Droplets ranging in sizes from 3 mm to 1 cm diameter were injected into the silicone oil. The vertical temperature profile in the bulk liquid (silicone oil) produces temperature variations along the interface which induce variations in the interfacial tension. The flow inside the droplet driven by the resulting interfacial shear stresses was observed using a laser light-sheet flow visualization technique. The flow direction is consistent with the sign of (d sigma)/(d T). The observed maximum surface velocities are compared to the theoretical predictions of Young et al. (1959).

  16. Emissions Prediction and Measurement for Liquid-Fueled TVC Combustor with and without Water Injection

    NASA Technical Reports Server (NTRS)

    Brankovic, A.; Ryder, R. C., Jr.; Hendricks, R. C.; Liu, N.-S.; Shouse, D. T.; Roquemore, W. M.

    2005-01-01

    An investigation is performed to evaluate the performance of a computational fluid dynamics (CFD) tool for the prediction of the reacting flow in a liquid-fueled combustor that uses water injection for control of pollutant emissions. The experiment consists of a multisector, liquid-fueled combustor rig operated at different inlet pressures and temperatures, and over a range of fuel/air and water/fuel ratios. Fuel can be injected directly into the main combustion airstream and into the cavities. Test rig performance is characterized by combustor exit quantities such as temperature and emissions measurements using rakes and overall pressure drop from upstream plenum to combustor exit. Visualization of the flame is performed using gray scale and color still photographs and high-frame-rate videos. CFD simulations are performed utilizing a methodology that includes computer-aided design (CAD) solid modeling of the geometry, parallel processing over networked computers, and graphical and quantitative post-processing. Physical models include liquid fuel droplet dynamics and evaporation, with combustion modeled using a hybrid finite-rate chemistry model developed for Jet-A fuel. CFD and experimental results are compared for cases with cavity-only fueling, while numerical studies of cavity and main fueling was also performed. Predicted and measured trends in combustor exit temperature, CO and NOx are in general agreement at the different water/fuel loading rates, although quantitative differences exist between the predictions and measurements.

  17. Experimental investigation of water droplet-air flow interaction in a non-reacting PEM fuel cell channel

    NASA Astrophysics Data System (ADS)

    Esposito, Angelo; Montello, Aaron D.; Guezennec, Yann G.; Pianese, Cesare

    It has been well documented that water production in PEM fuel cells occurs in discrete locations, resulting in the formation and growth of discrete droplets on the gas diffusion layer (GDL) surface within the gas flow channels (GFCs). This research uses a simulated fuel cell GFC with three transparent walls in conjunction with a high speed fluorescence photometry system to capture videos of dynamically deforming droplets. Such videos clearly show that the droplets undergo oscillatory deformation patterns. Although many authors have previously investigated the air flow induced droplet detachment, none of them have studied these oscillatory modes. The novelty of this work is to process and analyze the recorded videos to gather information on the droplets induced oscillation. Plots are formulated to indicate the dominant horizontal and vertical deformation frequency components over the range of sizes of droplets from formation to detachment. The system is also used to characterize droplet detachment size at a variety of channel air velocities. A simplified model to explain the droplet oscillation mechanism is provided as well.

  18. Droplet Combustion and Soot Formation in Microgravity

    NASA Technical Reports Server (NTRS)

    Avedisian, C. Thomas

    1994-01-01

    One of the most complex processes involved in the combustion ot liquid fuels is the formation of soot. A well characterized flow field and simplified flame structure can improve considerably the understanding of soot formation processes. The simplest flame shape to analyze for a droplet is spherical with its associated one-dimensional flow field. It is a fundamental limit and the oldest and most often analyzed configuration of droplet combustion. Spherical symmetry in the droplet burning process will arise when there is no relative motion between the droplet and ambience or uneven heating around the droplet periphery, and buoyancy effects are negligible. The flame and droplet are then concentric with each other and there is no liquid circulation within the droplet. An understanding of the effect of soot on droplet combustion should therefore benefit from this simplified configuration. Soot formed during spherically symmetric droplet combustion, however, has only recently drawn attention and it appears to be one of the few aspects associated with droplet combustion which have not yet been thoroughly investigated. For this review, the broad subject of droplet combustion is narrowed considerably by restricting attention specifically to soot combined with spherically symmetric droplet burning processes that are promoted.

  19. Nucleation of liquid droplets and voids in a stretched Lennard-Jones fcc crystal

    SciTech Connect

    Baidakov, Vladimir G. Tipeev, Azat O.

    2015-09-28

    The method of molecular dynamics simulation has been used to investigate the phase decay of a metastable Lennard-Jones face-centered cubic crystal at positive and negative pressures. It is shown that at high degrees of metastability, crystal decay proceeds through the spontaneous formation and growth of new-phase nuclei. It has been found that there exists a certain boundary temperature. Below this temperature, the crystal phase disintegrates as the result of formation of voids, and above, as a result of formation of liquid droplets. The boundary temperature corresponds to the temperature of cessation of a crystal–liquid phase equilibrium when the melting line comes in contact with the spinodal of the stretched liquid. The results of the simulations are interpreted in the framework of classical nucleation theory. The thermodynamics of phase transitions in solids has been examined with allowance for the elastic energy of stresses arising owing to the difference in the densities of the initial and the forming phases. As a result of the action of elastic forces, at negative pressures, the boundary of the limiting superheating (stretching) of a crystal approaches the spinodal, on which the isothermal bulk modulus of dilatation becomes equal to zero. At the boundary of the limiting superheating (stretching), the shape of liquid droplets and voids is close to the spherical one.

  20. Nucleation of liquid droplets and voids in a stretched Lennard-Jones fcc crystal.

    PubMed

    Baidakov, Vladimir G; Tipeev, Azat O

    2015-09-28

    The method of molecular dynamics simulation has been used to investigate the phase decay of a metastable Lennard-Jones face-centered cubic crystal at positive and negative pressures. It is shown that at high degrees of metastability, crystal decay proceeds through the spontaneous formation and growth of new-phase nuclei. It has been found that there exists a certain boundary temperature. Below this temperature, the crystal phase disintegrates as the result of formation of voids, and above, as a result of formation of liquid droplets. The boundary temperature corresponds to the temperature of cessation of a crystal-liquid phase equilibrium when the melting line comes in contact with the spinodal of the stretched liquid. The results of the simulations are interpreted in the framework of classical nucleation theory. The thermodynamics of phase transitions in solids has been examined with allowance for the elastic energy of stresses arising owing to the difference in the densities of the initial and the forming phases. As a result of the action of elastic forces, at negative pressures, the boundary of the limiting superheating (stretching) of a crystal approaches the spinodal, on which the isothermal bulk modulus of dilatation becomes equal to zero. At the boundary of the limiting superheating (stretching), the shape of liquid droplets and voids is close to the spherical one.

  1. Instabilities and boundary effects in a droplet of active polar liquid crystal

    NASA Astrophysics Data System (ADS)

    Whitfield, Carl; Hawkins, Rhoda

    2015-03-01

    Using the active gel theoretical framework, we have performed analytical calculations and numerical simulations of a droplet of active polar liquid crystal at low Reynolds number. This system is a simplified model of a cytoskeletal network that generates internal stresses by converting chemical energy (in the form of ATP) into mechanical work via molecular motors. A physical understanding of these systems can give an insight into the complex and varied dynamics of eukaryotic cell migration and division. We perform a linear stability analysis on the system by separating the behaviour into two limits. One where the internal polarisation is dominated by the shape of the boundary and one where it is deformed by the activity. We find that the two regimes show different instability thresholds for the activity parameter suggesting interesting behaviour both in and between these limits. We also simulate the system numerically and find the resulting steady state of the droplet for a range of parameters between these two limits.

  2. Investigation of Liquid Surface Rheology of Surfactant Solutions by Droplet Shape Oscillations: Experiments

    PubMed

    Tian; Holt; Apfel

    1997-03-01

    The experimental results of droplet shape oscillations are reported and applied to the analysis of surface rheological properties of surfactant solutions. An acoustic levitation technique is used to suspend the test drop in air and excite it into quadrupole shape oscillations. The equilibrium surface tension, Gibbs elasticity, and surface dilatational viscosity are determined from the measurements of droplet static shape under different levitation sound pressure, oscillation frequency, and free damping constant. Aqueous solutions of sodium dodecyl sulfate, dodecyltrimethylammonium bromide, and n-octyl beta-d-glucopyranoside are tested with this system. The concentrations of the solutions are below the critical micelle concentration. For these solutions it is found that the surface Gibbs elasticity approaches a maximum at a moderate concentration, and its value is less than that directly calculated from the state equation of a static liquid surface. The surface dilatational viscosity is found to be in a range around 0.1 cps. PMID:9245310

  3. Infrared thermography-based visualization of droplet transport in liquid sprays

    NASA Astrophysics Data System (ADS)

    Akafuah, Nelson K.; Salazar, Abraham J.; Saito, Kozo

    2010-05-01

    An infrared thermography-based technique for the characterization and visualization of liquid sprays was developed. The technique was tested on two atomizers: a high-speed rotary bell atomizer and a high volume low pressure air-assisted atomizer. The technique uses an infrared thermography-based measurement in which a uniformly heated background acts as a thermal radiation source, and an infrared camera as the receiver. The infrared energy emitted by the radiation source in traveling through the spray is attenuated by the presence of the droplets inside the spray. The infrared intensity is captured by the receiver showing the attenuation in the image as a result of the presence of the spray. The captured thermal image is used to study detailed macroscopic features of the spray flow field and the evolution of the paint droplets as they are transferred from the applicator to the target surface.

  4. Liquid-Water Uptake and Removal in PEM Fuel-Cell Components

    SciTech Connect

    Das, Prodip K.; Gunterman, Haluna P.; Kwong, Anthony; Weber, Adam Z.

    2011-09-23

    Management of liquid water is critical for optimal fuel-cell operation, especially at low temperatures. It is therefore important to understand the wetting properties and water holdup of the various fuel-cell layers. While the gas-diffusion layer is relatively hydrophobic and exhibits a strong intermediate wettability, the catalyst layer is predominantly hydrophilic. In addition, the water content of the ionomer in the catalyst layer is lower than that of the bulk membrane, and is affected by platinum surfaces. Liquid-water removal occurs through droplets on the surface of the gas-diffusion layer. In order to predict droplet instability and detachment, a force balance is used. While the pressure or drag force on the droplet can be derived, the adhesion or surface-tension force requires measurement using a sliding-angle approach. It is shown that droplets produced by forcing water through the gas-diffusion layer rather than placing them on top of it show much stronger adhesion forces owing to the contact to the subsurface water.

  5. Coal and Biomass to Liquid Fuels

    EPA Science Inventory

    For Frank Princiotta’s book, Global Climate Change—The Technology Challenge Demand for liquid transportation fuels has been increasing by over 2%/yr over the last two decades and is accelerating in the emerging economies which are moving to automobile ownership. Almost all liq...

  6. Liquid Fuels from Lignins: Annual Report

    SciTech Connect

    Chum, H. L.; Johnson, D. K.

    1986-01-01

    This task was initiated to assess the conversion of lignins into liquid fuels, primarily of lignins relevant to biomass-to-ethanol conversion processes. The task was composed of a literature review of this area and an experimental part to obtain pertinent data on the conversion of lignins germane to biomass-to-ethanol conversion processes.

  7. Milking liquid nano-droplets by an IR laser: a new modality for the visualization of electric field lines

    NASA Astrophysics Data System (ADS)

    Vespini, Veronica; Coppola, Sara; Grilli, Simonetta; Paturzo, Melania; Ferraro, Pietro

    2013-04-01

    Liquid handling at micron- and nano-scale is of paramount importance in many fields of application such as biotechnology and biochemistry. In fact, the microfluidics technologies play an important role in lab-on-a-chip devices and, in particular, the dispensing of liquid droplets is a required functionality. Different approaches have been developed for manipulating, dispensing and controlling nano-droplets under a wide variety of configurations. Here we demonstrate that nano-droplets can be drawn from liquid drop or film reservoirs through a sort of milking effect achieved by the absorption of IR laser radiation into a pyroelectric crystal. The generation of the pyroelectric field induced by the IR laser is calculated numerically and a specific experiment has been designed to visualize the electric field stream lines that are responsible for the liquid milking effect. The experiments performed are expected to open a new route for the visualization, measure and characterization procedures in the case of electrohydrodynamic applications.

  8. Swimming Droplets

    NASA Astrophysics Data System (ADS)

    Maass, Corinna C.; Krüger, Carsten; Herminghaus, Stephan; Bahr, Christian

    2016-03-01

    Swimming droplets are artificial microswimmers based on liquid droplets that show self-propelled motion when immersed in a second liquid. These systems are of tremendous interest as experimental models for the study of collective dynamics far from thermal equilibrium. For biological systems, such as bacterial colonies, plankton, or fish swarms, swimming droplets can provide a vital link between simulations and real life. We review the experimental systems and discuss the mechanisms of self-propulsion. Most systems are based on surfactant-stabilized droplets, the surfactant layer of which is modified in a way that leads to a steady Marangoni stress resulting in an autonomous motion of the droplet. The modification of the surfactant layer is caused either by the advection of a chemical reactant or by a solubilization process. Some types of swimming droplets possess a very simple design and long active periods, rendering them promising model systems for future studies of collective behavior.

  9. Effect of oil droplets and their solid/liquid composition on the phase separation of protein-polysaccharide mixtures.

    PubMed

    Hanazawa, Tomohito; Murray, Brent S

    2013-08-01

    The phase separation of a model system consisting of sodium caseinate + xanthan ± a low fraction (up to 3 wt %) of an oil-in-water emulsion was studied at room temperature (20-25 °C). The composition of the oil phase was either 100 wt % n-tetradecane (TD); 50% TD + 50% eicosane (EC) or 100% EC. The droplets in these three "emulsions" were therefore totally liquid, partially solid, and totally solid, respectively. In the presence of 22 mM CaCl2, the mixed TD+EC droplets were most effective at inhibiting phase separation, while the EC emulsions could not prevent phase separation at all. At 32 mM CaCl2 the emulsions tended to promote phase separation, possibly due to enhanced calcium ion-induced droplet aggregation. The apparent interfacial viscosity (ηi) between two macroscopically separated phases was also measured. In the presence of the semisolid mixed droplets ηi = 25 mN s m(-1), significantly higher than ηi with the pure (liquid) TD droplets (15 mN s m(-1)) or with the pure solid EC droplets (12 mN s m(-1)) or in the absence of droplets (<3 mN s m(-1)). Confocal microscopy showed that the microstructure of the phase separating regions also depended upon the composition of the oil droplets, and it is tentatively suggested that the more marked effects of the mixed emulsion droplets were due to them forming a stronger network at the interface via partial coalescence. Control of the extent of interfacial aggregation of droplets is therefore possibly one way to influence the course of phase separation in biopolymer mixtures. PMID:23805874

  10. Investigation of the Extinguishing Features for Liquid Fuels and Organic Flammable Liquids Atomized by a Water Flow

    NASA Astrophysics Data System (ADS)

    Voytkov, Ivan V.; Zabelin, Maksim V.; Vysokomornaya, Olga V.

    2016-02-01

    The processes of heat and mass transfer were investigated experimentally while moving and evaporating the atomized water flow in high-temperature combustion products of typical liquid fuels and organic flammable liquids: gasoline, kerosene, acetone, crude oil, industrial alcohol. We determined typical periods of liquid extinguishing by an atomized water flow of various dispersability. Data of the discharge of extinguishing medium corresponding to various parameters of atomization and duration of using the atomization devices was presented. It is shown that Um≈3.5 m/s is a minimal outflow velocity of droplets during moving while passing the distance of 1m in the high-temperature gas medium to stop the combustion of organic liquids.

  11. Fiber-Supported Droplet Combustion Experiment-2

    NASA Technical Reports Server (NTRS)

    Colantonio, Renato O.

    1998-01-01

    A major portion of the energy produced in the world today comes from the burning of liquid hydrocarbon fuels in the form of droplets. Understanding the fundamental physical processes involved in droplet combustion is not only important in energy production but also in propulsion, in the mitigation of combustion-generated pollution, and in the control of the fire hazards associated with handling liquid combustibles. Microgravity makes spherically symmetric combustion possible, allowing investigators to easily validate their droplet models without the complicating effects of gravity. The Fiber-Supported Droplet Combustion (FSDC-2) investigation was conducted in the Microgravity Glovebox facility of the shuttles' Spacelab during the reflight of the Microgravity Science Laboratory (MSL- 1R) on STS-94 in July 1997. FSDC-2 studied fundamental phenomena related to liquid fuel droplet combustion in air. Pure fuels and mixtures of fuels were burned as isolated single and duo droplets with and without forced air convection. FSDC-2 is sponsored by the NASA Lewis Research Center, whose researchers are working in cooperation with several investigators from industry and academia. The rate at which a droplet burns is important in many commercial applications. The classical theory of droplet burning assumes that, for an isolated, spherically symmetric, single-fuel droplet, the gas-phase combustion processes are much faster than the droplet surface regression rate and that the liquid phase is at a uniform temperature equal to the boiling point. Recent, more advanced models predict that both the liquid and gas phases are unsteady during a substantial portion of the droplet's burning history, thus affecting the instantaneous and average burning rates, and that flame radiation is a dominant mechanism that can extinguish flames in a microgravity environment. FSDC-2 has provided well-defined, symmetric droplet burning data including radiative emissions to validate these theoretical

  12. Tunable liquid crystal microlenses with crater polymer prepared by droplet evaporation.

    PubMed

    Hwang, Shug-June; Liu, Yi-Xiang; Porter, Glen Andrew

    2013-12-16

    A simple and low-cost technique is proposed to construct a tunable liquid crystal (LC) microlens with a crater polymer structure, which is prepared using micro-drop technology and 2-step UV polymerization. The dimensions and the geometric profile of the restructured polymer surface significantly depend on the volume of the micro droplet, and the UV irradiation dose. In this work, the focal length of the LC microlens is controlled electrically from infinity to 7.8 cm. Such a microlens has prospective applications in optical communications, image processing, and switchable 2D/3D displays.

  13. Characteristics of droplets ejected from liquid glycerol doped with carbon in laser ablation propulsion

    NASA Astrophysics Data System (ADS)

    Zhi-Yuan, Zheng; Si-Qi, Zhang; Tian, Liang; Lu, Gao; Hua, Gao; Zi-Li, Zhang

    2016-04-01

    The characteristics of droplets ejected from liquid glycerol doped with carbon are investigated in laser ablation propulsion. Results show that carbon content has an effect on both the coupling coefficient and the specific impulse. The doped-carbon moves the laser focal position from the glycerol interior to the surface. This results in a less consumed glycerol and a high specific impulse. An optimal propulsion can be realized by varying carbon content in glycerol. Project supported by the National Natural Science Foundation of China (Grant No. 10905049) and the Fundamental Research Funds for the Central Universities, China (Grant Nos. 53200859165 and 2562010050).

  14. Negative pressures and melting point depression in oxide-coated liquid metal droplets

    NASA Technical Reports Server (NTRS)

    Spaepen, F.; Turnbull, D.

    1979-01-01

    Negative pressures and melting point depression in oxide-coated liquid metal droplets are studied. The calculation presented show the existence of large negative pressures when the oxide coating is thick enough. The change in the melting point caused by these negative pressures should be considered in studies of homogeneous crystal nucleation. Furthermore, since the negative pressure raises the entropy of the melt, it increases the entropy loss at the crystal-melt interface; the resulting increase of the surface tension could have a large effect on the homogeneous nucleation frequency.

  15. Simulation and experimental validation of droplet dynamics in microchannels of PEM fuel cells

    NASA Astrophysics Data System (ADS)

    Ashrafi, Moosa; Shams, Mehrzad; Bozorgnezhad, Ali; Ahmadi, Goodarz

    2016-02-01

    In this study, dynamics of droplets in the channels of proton exchange membrane fuel cells with straight and serpentine flow-fields was investigated. Tapered and filleted channels were suggested for the straight and serpentine flow-fields respectively in order to improve water removal in channels. Surface tension and wall adhesion forces were applied by using the volume of fluid method. The hydrophilic walls and hydrophobic gas diffusion layer were considered. The mechanism of droplets movement with different diameters was studied by using the Weber and capillary numbers in simple and tapered straight channels. It was illustrated that the flooding was reduced in tapered channel due to increase of water removal rate, and available reaction sites improved subsequently. In addition, film flow was formed in the tapered channel more than the simple channel, so pressure fluctuation was decreased in the tapered channel. Moreover, the water coverage ratio of hydrophilic tapered surface was more than the simple channel, which enhanced water removal from the channel. The filleted serpentine channel was introduced to improve water removal from the simple serpentine channel. It was shown by observation of the unsteady and time-averaged two-phase pressure drop that in the filleted serpentine channels, the two-phase pressure drop was far less than the simple serpentine channel, and also the accumulation of water droplets in the elbows was less leading to lower pressure fluctuation. The numerical simulation results were validated by experiments.

  16. Wetted Foam Liquid Fuel ICF Target Experiments

    NASA Astrophysics Data System (ADS)

    Olson, R.; Leeper, R.; Yi, A.; Zylstra, A.; Kline, J.; Peterson, R.; Braun, T.; Biener, J.; Biener, M.; Kozioziemski, B.; Sater, J.; Hamza, A.; Nikroo, A.; Berzak Hopkins, L.; Lepape, S.; MacKinnon, A.; Meezan, N.

    2015-11-01

    We are developing a new NIF experimental platform that employs wetted foam liquid fuel layer ICF capsules. We plan to use the liquid fuel layer capsules in a NIF experimental campaign to explore the relationship between hot spot convergence ratio (CR) and the robustness of hot spot formation. DT or D2 Liquid Layer ICF capsules allow for flexibility in hot spot convergence ratio via the adjustment of the initial cryogenic capsule temperature and, hence, DT vapor density. Our hypothesis is that the predictive capability of hot spot formation is robust and 1D-like for a relatively low CR hot spot (CR =15), but will become less reliable as hot spot CR is increased to CR>20. Simulations indicate that backing off on hot spot CR is an excellent way to reduce capsule instability growth and to improve robustness to low-mode x-ray flux asymmetries. In these initial experiments, we are testing our hypothesis by measuring hot spot size, neutron yield, ion temperature, and burn width to infer hot spot pressure and compare to predictions for implosions with hot spot CR's in the range of 12 to 25. Larger scale experiments are also being designed, with the longer-term objective of developing a liquid fuel layer ICF capsule platform with robust thermonuclear burn, modest CR, and significant α-heating with burn propagation.

  17. A combined droplet train and ambient pressure photoemission spectrometer for the investigation of liquid/vapor interfaces

    SciTech Connect

    Starr, David E.; Wong, Ed K.; Worsnop, Douglas R.; Wilson, Kevin R.; Bluhm, Hendrik

    2008-05-01

    We describe a combined ambient pressure photoelectron spectroscopy/droplet train apparatus for investigating the nature and heterogeneous chemistry of liquid/vapor interfaces. In this instrument a liquid droplet train with typical droplet diameters from 50...150 {micro}m is produced by a vibrating orifice aerosol generator (VOAG). The droplets are irradiated by soft X-rays (100...1500 eV) in front of the entrance aperture of a differentially pumped electrostatic lens system that transfers the emitted electrons into a conventional hemispherical electron analyzer. The photoemission experiments are performed at background pressures of up to several Torr, which allows the study of environmentally important liquid/vapor interfaces, in particular aqueous solutions, under equilibrium conditions. The exposure time of the droplet surface to the background gases prior to the XPS measurement can be varied, which will allow future kinetic measurements of gas uptake on liquid surfaces. As an example, a measurement of the surface composition of a {chi} = 0.21 aqueous methanol solution is presented. The concentration of methanol at the vapor/liquid interface is enhanced by a factor of about 3 over the bulk value, while the expected bulk value is recovered at depths larger than about 1.5 nm.

  18. A combined droplet train and ambient pressure photoemission spectrometer for the investigation of liquid/vapor interfaces.

    PubMed

    Starr, David E; Wong, Ed K; Worsnop, Douglas R; Wilson, Kevin R; Bluhm, Hendrik

    2008-06-01

    We describe a combined ambient pressure photoelectron spectroscopy/droplet train apparatus for investigating the nature and heterogeneous chemistry of liquid/vapor interfaces. In this instrument a liquid droplet train with typical droplet diameters from 50-150 mum is produced by a vibrating orifice aerosol generator (VOAG). The droplets are irradiated by soft X-rays (100-1500 eV) in front of the entrance aperture of a differentially pumped electrostatic lens system that transfers the emitted electrons into a conventional hemispherical electron analyzer. The photoemission experiments are performed at background pressures of up to several Torr, which allows the study of environmentally important liquid/vapor interfaces, in particular aqueous solutions, under equilibrium conditions. The exposure time of the droplet surface to the background gases prior to the XPS measurement can be varied, which will allow future kinetic measurements of gas uptake on liquid surfaces. As an example, a measurement of the surface composition of a chi = 0.21 aqueous methanol solution is presented. The concentration of methanol at the vapor/liquid interface is enhanced by a factor of about 3 over the bulk value, while the expected bulk value is recovered at depths larger than about 1.5 nm.

  19. Non-spill liquid fuel tanks

    SciTech Connect

    Chinn, B. P.; Armour, J. S.; Donne, G. L.; Watson, P. M. F.

    1985-01-08

    A liquid fuel tank for a vehicle is provided with a fuel outlet duct in a circuit about the base of the tank and fuel outlet duct vents connected to the outlet duct and extending above the highest part of the tank. During normal operation of the tank, a non-return air vent allows the flow of fuel from the outlet duct. In the event of an accident, or some other occurrence which results in the tank being tilted, further fuel flow from the outlet duct is cut off by air drawn into the fuel outlet duct from the outlet duct vents. The angle through which the tank must be tilted to allow air from the outlet duct vents to be drawn into the outlet duct may be predetermined by the extent of the circuit about the base of the tank of the outlet duct. Such a non-spill fuel tank, which is self contained in operation, is suitable for use in on-road and off-road wheeled and tracked vehicles, hover-craft and aircraft which are in danger of being blown over when on the ground.

  20. Simulation of vapor-liquid coexistence in finite volumes: a method to compute the surface free energy of droplets.

    PubMed

    Schrader, Manuel; Virnau, Peter; Binder, Kurt

    2009-06-01

    When a fluid at a constant density rho in between the densities of coexisting vapor (rhov) and liquid (rhol) at temperatures below criticality is studied in a (cubic) box of finite linear dimension L , phase separation occurs in this finite volume, provided L is large enough. For a range of densities, one can observe a liquid droplet (at density rhol' slightly exceeding rhol) coexisting in stable thermal equilibrium with surrounding vapor (with density rhov'>rhov, so in the thermodynamic limit such a vapor would be supersaturated). We show, via Monte Carlo simulations of a Lennard-Jones model of a fluid and based on a phenomenological thermodynamic analysis, that via recording the chemical potential micro as function of rho, one can obtain precise estimates of the droplet surface free energy for a wide range of droplet radii. We also show that the deviations of this surface free energy from the prediction based on the "capillarity approximation" of classical nucleation theory (i.e., using the interfacial free energy of a flat liquid-vapor interface for the surface free energy of a droplet irrespective of its radius) are rather small. We also study carefully the limitation of the present method due to the "droplet evaporation/condensation transition" occurring for small volumes and demonstrate that very good equilibrium is achieved in our study, by showing that the radial profile of the local chemical potential from the droplet center to the outside is perfectly flat.

  1. Laser-induced fluorescence for the non-intrusive diagnostics of a fuel droplet burning under microgravity in a drop shaft

    NASA Astrophysics Data System (ADS)

    Matsumoto, Kiyoshi; Fujii, Tomohiro; Suzuki, Katsumasa; Segawa, Daisuke; Kadota, Toshikazu

    1999-10-01

    The laser-induced-fluorescence method has been employed for remote, non-intrusive and instantaneous measurements of a fuel droplet burning under microgravity. A fuel droplet was doped with naphthalene and TMPD. The fluorescence emission spectra from a droplet subjected to the incident nitrogen laser beam were measured with an image-intensifying optical multichannel analyser. The microgravity was generated in a capsule of a 100 m drop shaft. The results showed that the newly developed diagnostic system could be applied successfully for the simultaneous measurements of droplet temperature and diameters of the droplet, flame and soot shell under microgravity. The droplet temperature was determined from the measured ratio of fluorescence emission intensities at two different wavelengths. The soot shell was located in the vicinity of the droplet surface deep inside the flame during the early stage of the burning and moved away from the droplet with the elapse of time.

  2. Combustion characteristics in the transition region of liquid fuel sprays

    NASA Technical Reports Server (NTRS)

    Cernansky, N. P.; Namer, I.; Tidona, R. J.; Sarv, H.

    1984-01-01

    A monodisperse aerosol generator was modified to study ignition requirements, flammability limits, and flame speeds in the transition region. An ignition system was developed and tested. The fabrication of an optical drop sizing system is nearly complete. Preliminary measurements of droplet size effects on the minimum ignition energy for n-heptane sprays performed. Parameteric studies of droplet size effects on minimum ignition energies of various fuels including alcohols are in progress.

  3. Combustion engine for solid and liquid fuels

    NASA Technical Reports Server (NTRS)

    Pabst, W.

    1986-01-01

    A combustion engine having no piston, a single cylinder, and a dual-action, that is applicable for solid and liquid fuels and propellants, and that functions according to the principle of annealing point ignition is presented. The invention uses environmentally benign amounts of fuel and propellants to produce gas and steam pressure, and to use a simple assembly with the lowest possible consumption and constant readiness for mixing and burning. The advantage over conventional combustion engines lies in lower consumption of high quality igniting fluid in the most cost effective manner.

  4. Computational simulation of liquid fuel rocket injectors

    NASA Technical Reports Server (NTRS)

    Landrum, D. Brian

    1994-01-01

    A major component of any liquid propellant rocket is the propellant injection system. Issues of interest include the degree of liquid vaporization and its impact on the combustion process, the pressure and temperature fields in the combustion chamber, and the cooling of the injector face and chamber walls. The Finite Difference Navier-Stokes (FDNS) code is a primary computational tool used in the MSFC Computational Fluid Dynamics Branch. The branch has dedicated a significant amount of resources to development of this code for prediction of both liquid and solid fuel rocket performance. The FDNS code is currently being upgraded to include the capability to model liquid/gas multi-phase flows for fuel injection simulation. An important aspect of this effort is benchmarking the code capabilities to predict existing experimental injection data. The objective of this MSFC/ASEE Summer Faculty Fellowship term was to evaluate the capabilities of the modified FDNS code to predict flow fields with liquid injection. Comparisons were made between code predictions and existing experimental data. A significant portion of the effort included a search for appropriate validation data. Also, code simulation deficiencies were identified.

  5. Coupled modeling of water transport and air-droplet interaction in the electrode of a proton exchange membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Esposito, Angelo; Pianese, Cesare; Guezennec, Yann G.

    In this work, an accurate and computationally fast model for liquid water transport within a proton exchange membrane fuel cell (PEMFC) electrode is developed by lumping the space-dependence of the relevant variables. Capillarity is considered as the main transport mechanism within the gas diffusion layer (GDL). The novelty of the model lies in the coupled simulation of the water transport at the interface between gas diffusion layer and gas flow channel (GFC). This is achieved with a phenomenological description of the process that allows its simulation with relative simplicity. Moreover, a detailed two-dimensional visualization of such interface is achieved via geometric simulation of water droplets formation, growth, coalescence and detachment on the surface of the GDL. The model is useful for optimization analysis oriented to both PEMFC design and balance of plant. Furthermore, the accomplishment of reduced computational time and good accuracy makes the model suitable for control strategy implementation to ensure PEM fuel cells operation within optimal electrode water content.

  6. Chemistry in the Venus clouds: Sulfuric acid reactions and freezing behavior of aqueous liquid droplets

    NASA Astrophysics Data System (ADS)

    Delitsky, M. L.; Baines, K. H.

    2015-11-01

    Venus has a thick cloud deck at 40-70 km altitude consisting of liquid droplets and solid particles surrounded by atmospheric gases. The liquid droplets are highly concentrated aqueous solutions of sulfuric acid ranging in concentration from 70-99 wt%. Weight percent drops off with altitude (Imamura and Hashimoto 2001). There will be uptake of atmospheric gases into the droplet solutions and the ratios of gas-phase to liquid-phase species will depend on the Henry’s Law constant for those solutions. Reactions of sulfuric acid with these gases will form products with differing solubilities. For example, uptake of HCl by H2SO4/H2O droplets yields chlorosulfonic acid, ClSO3H (Robinson et al 1998) in solution. This may eventually decompose to thionyl- or sulfuryl chlorides, which have UV absorbances. HF will also uptake, creating fluorosulfonic acid, FSO3H, which has a greater solubility than the chloro- acid. As uptake continues, there will be many dissolved species in the cloudwaters. Baines and Delitsky (2013) showed that uptake will have a maximum at ~62 km and this is very close to the reported altitude for the mystery UV absorber in the Venus atmosphere. In addition, at very strong concentrations in lower altitude clouds, sulfuric acid will form hydrates such as H2SO4.H2O and H2SO4.4H2O which will have very different freezing behavior than sulfuric acid, with much higher freezing temperatures (Carslaw et al, 1997). Using temperature data from Venus Express from Tellmann et al (2009), and changes in H2SO4 concentrations as a function of altitude (James et al 1997), we calculate that freezing out of sulfuric acid hydrates can be significant down to as low as 56 km altitude. As a result, balloons, aircraft or other probes in the Venus atmosphere may be limited to flying below certain altitudes. Any craft flying at altitudes above ~55 km may suffer icing on the wings, propellers, balloons and instruments which could cause possible detrimental effects (thermal

  7. Temperature dependence of droplet breakup in 8CB and 5CB liquid crystals

    NASA Astrophysics Data System (ADS)

    Porter, Daniel; Savage, John R.; Cohen, Itai; Spicer, Patrick; Caggioni, Marco

    2012-04-01

    Droplet breakup of many Newtonian fluids is well described by current experiments, theory, and simulations. Breakup in complex fluids where interactions between mesoscopic structural features can affect the flows remains poorly understood and a burgeoning area of research. Here, we report on our investigations of droplet breakup in thermotropic liquid crystals. We investigate breakup in the smectic, nematic, and isotropic phases of 4-cyano 4-octylbiphenyl (8CB) and the nematic and isotropic phases of 4-cyano 4-pentylbiphenyl (5CB). The experiment consists of varying the ambient temperature to control liquid crystalline phase and imaging breakup using a fast video camera at up to 110000 frames/s. We expand on previous work [John R. Savage , Soft Matter1744-683X10.1039/b923069f 6, 892 (2010)] that shows breakup in the smectic phase is symmetric, producing no satellite droplets, and is well described by a similarity solution for a shear-thinning power-law fluid. We show that in the nematic phase the breakup occurs in two stages. In the first stage, the breakup is symmetric and the power-law exponent for the minimum radius dependence on the time left to breakup is 1.2

  8. Mechanically Stretchable and Electrically Insulating Thermal Elastomer Composite by Liquid Alloy Droplet Embedment.

    PubMed

    Jeong, Seung Hee; Chen, Si; Huo, Jinxing; Gamstedt, Erik Kristofer; Liu, Johan; Zhang, Shi-Li; Zhang, Zhi-Bin; Hjort, Klas; Wu, Zhigang

    2015-12-16

    Stretchable electronics and soft robotics have shown unsurpassed features, inheriting remarkable functions from stretchable and soft materials. Electrically conductive and mechanically stretchable materials based on composites have been widely studied for stretchable electronics as electrical conductors using various combinations of materials. However, thermally tunable and stretchable materials, which have high potential in soft and stretchable thermal devices as interface or packaging materials, have not been sufficiently studied. Here, a mechanically stretchable and electrically insulating thermal elastomer composite is demonstrated, which can be easily processed for device fabrication. A liquid alloy is embedded as liquid droplet fillers in an elastomer matrix to achieve softness and stretchability. This new elastomer composite is expected useful to enhance thermal response or efficiency of soft and stretchable thermal devices or systems. The thermal elastomer composites demonstrate advantages such as thermal interface and packaging layers with thermal shrink films in transient and steady-state cases and a stretchable temperature sensor.

  9. Instability of nano- and microscale liquid metal filaments: Transition from single droplet collapse to multidroplet breakup

    SciTech Connect

    Hartnett, Chris A.; Mahady, Kyle; Fowlkes, Jason Davidson; Afkhami, Shahriar; Rack, P. D.; Kondic, L.

    2015-11-23

    We carry out experimental and numerical studies to investigate the collapse and breakup of finite size, nano- and microscale, liquid metal filaments supported on a substrate. We find the critical dimensions below which filaments do not break up but rather collapse to a single droplet. The transition from collapse to breakup can be described as a competition between two fluid dynamic phenomena: the capillary driven end retraction and the Rayleigh–Plateau type instability mechanism that drives the breakup. We focus on the unique spatial and temporal transition region between these two phenomena using patterned metallic thin film strips and pulsed-laser-induced dewetting. The experimental results are compared to an analytical model proposed by Driessen et al. and modified to include substrate interactions. Additionally, we report the results of numerical simulations based on a volume-of-fluid method to provide additional insight and highlight the importance of liquid metal resolidification, which reduces inertial effects.

  10. Mechanically Stretchable and Electrically Insulating Thermal Elastomer Composite by Liquid Alloy Droplet Embedment.

    PubMed

    Jeong, Seung Hee; Chen, Si; Huo, Jinxing; Gamstedt, Erik Kristofer; Liu, Johan; Zhang, Shi-Li; Zhang, Zhi-Bin; Hjort, Klas; Wu, Zhigang

    2015-01-01

    Stretchable electronics and soft robotics have shown unsurpassed features, inheriting remarkable functions from stretchable and soft materials. Electrically conductive and mechanically stretchable materials based on composites have been widely studied for stretchable electronics as electrical conductors using various combinations of materials. However, thermally tunable and stretchable materials, which have high potential in soft and stretchable thermal devices as interface or packaging materials, have not been sufficiently studied. Here, a mechanically stretchable and electrically insulating thermal elastomer composite is demonstrated, which can be easily processed for device fabrication. A liquid alloy is embedded as liquid droplet fillers in an elastomer matrix to achieve softness and stretchability. This new elastomer composite is expected useful to enhance thermal response or efficiency of soft and stretchable thermal devices or systems. The thermal elastomer composites demonstrate advantages such as thermal interface and packaging layers with thermal shrink films in transient and steady-state cases and a stretchable temperature sensor. PMID:26671673

  11. Mechanically Stretchable and Electrically Insulating Thermal Elastomer Composite by Liquid Alloy Droplet Embedment

    NASA Astrophysics Data System (ADS)

    Jeong, Seung Hee; Chen, Si; Huo, Jinxing; Gamstedt, Erik Kristofer; Liu, Johan; Zhang, Shi-Li; Zhang, Zhi-Bin; Hjort, Klas; Wu, Zhigang

    2015-12-01

    Stretchable electronics and soft robotics have shown unsurpassed features, inheriting remarkable functions from stretchable and soft materials. Electrically conductive and mechanically stretchable materials based on composites have been widely studied for stretchable electronics as electrical conductors using various combinations of materials. However, thermally tunable and stretchable materials, which have high potential in soft and stretchable thermal devices as interface or packaging materials, have not been sufficiently studied. Here, a mechanically stretchable and electrically insulating thermal elastomer composite is demonstrated, which can be easily processed for device fabrication. A liquid alloy is embedded as liquid droplet fillers in an elastomer matrix to achieve softness and stretchability. This new elastomer composite is expected useful to enhance thermal response or efficiency of soft and stretchable thermal devices or systems. The thermal elastomer composites demonstrate advantages such as thermal interface and packaging layers with thermal shrink films in transient and steady-state cases and a stretchable temperature sensor.

  12. Mechanically Stretchable and Electrically Insulating Thermal Elastomer Composite by Liquid Alloy Droplet Embedment

    PubMed Central

    Jeong, Seung Hee; Chen, Si; Huo, Jinxing; Gamstedt, Erik Kristofer; Liu, Johan; Zhang, Shi-Li; Zhang, Zhi-Bin; Hjort, Klas; Wu, Zhigang

    2015-01-01

    Stretchable electronics and soft robotics have shown unsurpassed features, inheriting remarkable functions from stretchable and soft materials. Electrically conductive and mechanically stretchable materials based on composites have been widely studied for stretchable electronics as electrical conductors using various combinations of materials. However, thermally tunable and stretchable materials, which have high potential in soft and stretchable thermal devices as interface or packaging materials, have not been sufficiently studied. Here, a mechanically stretchable and electrically insulating thermal elastomer composite is demonstrated, which can be easily processed for device fabrication. A liquid alloy is embedded as liquid droplet fillers in an elastomer matrix to achieve softness and stretchability. This new elastomer composite is expected useful to enhance thermal response or efficiency of soft and stretchable thermal devices or systems. The thermal elastomer composites demonstrate advantages such as thermal interface and packaging layers with thermal shrink films in transient and steady-state cases and a stretchable temperature sensor. PMID:26671673

  13. Active suppression of vortex-driven combustion instability using controlled liquid-fuel injection

    NASA Astrophysics Data System (ADS)

    Pang, Bin

    Combustion instabilities remain one of the most challenging problems encountered in developing propulsion and power systems. Large amplitude pressure oscillations, driven by unsteady heat release, can produce numerous detrimental effects. Most previous active control studies utilized gaseous fuels to suppress combustion instabilities. However, using liquid fuel to suppress combustion instabilities is more realistic for propulsion applications. Active instability suppression in vortex-driven combustors using a direct liquid fuel injection strategy was theoretically established and experimentally demonstrated in this dissertation work. Droplet size measurements revealed that with pulsed fuel injection management, fuel droplet size could be modulated periodically. Consequently, desired heat release fluctuation could be created. If this oscillatory heat release is coupled with the natural pressure oscillation in an out of phase manner, combustion instabilities can be suppressed. To identify proper locations of supplying additional liquid fuel for the purpose of achieving control, the natural heat release pattern in a vortex-driven combustor was characterized in this study. It was found that at high Damkohler number oscillatory heat release pattern closely followed the evolving vortex front. However, when Damkohler number became close to unity, heat release fluctuation wave no longer coincided with the coherent structures. A heat release deficit area was found near the dump plane when combustor was operated in lean premixed conditions. Active combustion instability suppression experiments were performed in a dump combustor using a controlled liquid fuel injection strategy. High-speed Schlieren results illustrated that vortex shedding plays an important role in maintaining self-sustained combustion instabilities. Complete combustion instability control requires total suppression of these large-scale coherent structures. The sound pressure level at the excited dominant

  14. Silicon Wafer Cleaning Using New Liquid Aerosol with Controlled Droplet Velocity and Size by Rotary Atomizer Method

    NASA Astrophysics Data System (ADS)

    Seike, Yoshiyuki; Miyachi, Keiji; Shibata, Tatsuo; Kobayashi, Yoshinori; Kurokawa, Syuhei; Doi, Toshiro

    2010-06-01

    A liquid aerosol, which sprays cleaning liquid with a carrier gas, is widely used for cleaning semiconductor devices. The liquid aerosol using a conventional two-fluid nozzle may cause pattern damage on the wafer. To resolve this problem, we have made a prototype new rotary atomizing two-fluid cleaning nozzle (RAC nozzle), which can control the velocity distribution and size distribution of flying liquid droplets separately. It was confirmed by measuring flying liquid droplets using a shadow Doppler particle analyzer system that the mean volumetric diameter of the droplets could be atomized to 20 µm or less at a rotational speed of the air turbine of 50,000 min-1 and that the mean velocity of the flying liquid droplets could be controlled in the range under 65 m/s independently. It was confirmed in a cleaning experiment using polystyrene latex (PSL) particles on a wafer that particle removal efficiency increased when shaping air pressure increased. Also, the particle removal efficiency was improved with the finer atomization promoted by a higher rotational speed of the air turbine.

  15. Silicon Wafer Cleaning Using New Liquid Aerosol with Controlled Droplet Velocity and Size by Rotary Atomizer Method

    NASA Astrophysics Data System (ADS)

    Yoshiyuki Seike,; Keiji Miyachi,; Tatsuo Shibata,; Yoshinori Kobayashi,; Syuhei Kurokawa,; Toshiro Doi,

    2010-06-01

    A liquid aerosol, which sprays cleaning liquid with a carrier gas, is widely used for cleaning semiconductor devices. The liquid aerosol using a conventional two-fluid nozzle may cause pattern damage on the wafer. To resolve this problem, we have made a prototype new rotary atomizing two-fluid cleaning nozzle (RAC nozzle), which can control the velocity distribution and size distribution of flying liquid droplets separately. It was confirmed by measuring flying liquid droplets using a shadow Doppler particle analyzer system that the mean volumetric diameter of the droplets could be atomized to 20 μm or less at a rotational speed of the air turbine of 50,000 min-1 and that the mean velocity of the flying liquid droplets could be controlled in the range under 65 m/s independently. It was confirmed in a cleaning experiment using polystyrene latex (PSL) particles on a wafer that particle removal efficiency increased when shaping air pressure increased. Also, the particle removal efficiency was improved with the finer atomization promoted by a higher rotational speed of the air turbine.

  16. Reimagining liquid transportation fuels : sunshine to petrol.

    SciTech Connect

    Johnson, Terry Alan; Hogan, Roy E., Jr.; McDaniel, Anthony H.; Siegel, Nathan Phillip; Dedrick, Daniel E.; Stechel, Ellen Beth; Diver, Richard B., Jr.; Miller, James Edward; Allendorf, Mark D.; Ambrosini, Andrea; Coker, Eric Nicholas; Staiger, Chad Lynn; Chen, Ken Shuang; Ermanoski, Ivan; Kellog, Gary L.

    2012-01-01

    Two of the most daunting problems facing humankind in the twenty-first century are energy security and climate change. This report summarizes work accomplished towards addressing these problems through the execution of a Grand Challenge LDRD project (FY09-11). The vision of Sunshine to Petrol is captured in one deceptively simple chemical equation: Solar Energy + xCO{sub 2} + (x+1)H{sub 2}O {yields} C{sub x}H{sub 2x+2}(liquid fuel) + (1.5x+.5)O{sub 2} Practical implementation of this equation may seem far-fetched, since it effectively describes the use of solar energy to reverse combustion. However, it is also representative of the photosynthetic processes responsible for much of life on earth and, as such, summarizes the biomass approach to fuels production. It is our contention that an alternative approach, one that is not limited by efficiency of photosynthesis and more directly leads to a liquid fuel, is desirable. The development of a process that efficiently, cost effectively, and sustainably reenergizes thermodynamically spent feedstocks to create reactive fuel intermediates would be an unparalleled achievement and is the key challenge that must be surmounted to solve the intertwined problems of accelerating energy demand and climate change. We proposed that the direct thermochemical conversion of CO{sub 2} and H{sub 2}O to CO and H{sub 2}, which are the universal building blocks for synthetic fuels, serve as the basis for this revolutionary process. To realize this concept, we addressed complex chemical, materials science, and engineering problems associated with thermochemical heat engines and the crucial metal-oxide working-materials deployed therein. By project's end, we had demonstrated solar-driven conversion of CO{sub 2} to CO, a key energetic synthetic fuel intermediate, at 1.7% efficiency.

  17. Numerical Simulation of the Combustion of Fuel Droplets: Finite Rate Kinetics and Flame Zone Grid Adaptation (CEFD)

    NASA Technical Reports Server (NTRS)

    Gogos, George; Bowen, Brent D.; Nickerson, Jocelyn S.

    2002-01-01

    The NASA Nebraska Space Grant (NSGC) & EPSCoR programs have continued their effort to support outstanding research endeavors by funding the Numerical Simulation of the Combustion of Fuel Droplets study at the University of Nebraska at Lincoln (UNL). This team of researchers has developed a transient numerical model to study the combustion of suspended and moving droplets. The engines that propel missiles, jets, and many other devices are dependent upon combustion. Therefore, data concerning the combustion of fuel droplets is of immediate relevance to aviation and aeronautical personnel, especially those involved in flight operations. The experiments being conducted by Dr. Gogos and Dr. Nayagam s research teams, allow investigators to gather data for comparison with theoretical predictions of burning rates, flame structures, and extinction conditions. The consequent improved hndamental understanding droplet combustion may contribute to the clean and safe utilization of fossil hels (Williams, Dryer, Haggard & Nayagam, 1997, 72). The present state of knowledge on convective extinction of he1 droplets derives fiom experiments conducted under normal gravity conditions. However, any data obtained with suspended droplets under normal gravity are grossly affected by gravity. The need to obtain experimental data under microgravity conditions is therefore well justified and addresses one of the goals of NASA s Human Exploration and Development of Space (HEDS) microgravity combustion experiment.

  18. Electronic absorption spectroscopy of PAHs in supersonic jets and ultracold liquid helium droplets

    NASA Astrophysics Data System (ADS)

    Huisken, Friedrich; Staicu, Angela; Krasnokutski, Serge; Henning, Thomas

    Neutral and cationic polycyclic aromatic hydrocarbons (PAHs) are discussed as possible carriers of the diffuse interstellar bands (DIBs), still unassigned astrophysical absorption features observed in the spectra of reddened stars (Salama et al. 1999). Despite the importance of this class of molecules for astrophysics and nanophysics (PAHs can be regarded as nanoscale fragments of a sheet of graphite), the spectroscopic characterization of PAHs under well-defined conditions (low temperature and collision-free environment) has remained a challenge. Recently we have set up a cavity ring-down spectrometer combined with a pulsed supersonic jet expansion to study neutral and cationic PAHs under astrophysical conditions. PAHs studied so far include the neutral molecules anthracene (Staicu et al. 2004) and pyrene (Rouillé et al. 2004) as well as the cationic species naphthalene+ and anthracene+ (Sukhorukov et al. 2004). Employing another molecular beam apparatus, the same molecules (except of the cationic species) were also studied in liquid helium droplets (Krasnokutski et al. 2005, Rouillé et al. 2004). This novel technique combines several advantages of conventional matrix spectroscopy with those of gas phase spectroscopy. Notable advantages are the possibility to study molecules with low vapor pressure and to use a mass spectrometer facilitating spectral assignments. The most recent studies were devoted to phenanthrene and the more complicated (2,3)-benzofluorene. These molecules were investigated in the gas phase by cavity ring-down spectroscopy and in liquid helium droplets using depletion spectroscopy. For benzofluorene the present studies constitute the first reported measurements both in the gas phase and in helium droplets. The origin of the S1 ← S0 gas phase transition could be located at 29 894.3 cm-1, and a series of vibronic bands was recorded below 31 500 cm-1. In contrast to previously studied PAHs, the shift induced by the helium droplets was very

  19. Stable water isotopologue ratios in fog and cloud droplets of liquid clouds are not size-dependent

    USGS Publications Warehouse

    Spiegel, J.K.; Aemisegger, F.; Scholl, M.; Wienhold, F.G.; Collett, J.L.; Lee, T.; van Pinxteren, D.; Mertes, S.; Tilgner, A.; Herrmann, H.; Werner, Roland A.; Buchmann, N.; Eugster, W.

    2012-01-01

    In this work, we present the first observations of stable water isotopologue ratios in cloud droplets of different sizes collected simultaneously. We address the question whether the isotope ratio of droplets in a liquid cloud varies as a function of droplet size. Samples were collected from a ground intercepted cloud (= fog) during the Hill Cap Cloud Thuringia 2010 campaign (HCCT-2010) using a three-stage Caltech Active Strand Cloud water Collector (CASCC). An instrument test revealed that no artificial isotopic fractionation occurs during sample collection with the CASCC. Furthermore, we could experimentally confirm the hypothesis that the δ values of cloud droplets of the relevant droplet sizes (μm-range) were not significantly different and thus can be assumed to be in isotopic equilibrium immediately with the surrounding water vapor. However, during the dissolution period of the cloud, when the supersaturation inside the cloud decreased and the cloud began to clear, differences in isotope ratios of the different droplet sizes tended to be larger. This is likely to result from the cloud's heterogeneity, implying that larger and smaller cloud droplets have been collected at different moments in time, delivering isotope ratios from different collection times.

  20. Gradient polymer-disposed liquid crystal single layer of large nematic droplets for modulation of laser light.

    PubMed

    Hadjichristov, Georgi B; Marinov, Yordan G; Petrov, Alexander G

    2011-06-01

    The light modulating ability of gradient polymer-disposed liquid crystal (PDLC) single layer of large droplets formed by nematic E7 in UV-cured polymer NOA65 is studied. Operating at relatively low voltages, such PDLC film with a of thickness 10-25 μm and droplet size up to 50 μm exhibits a good contrast ratio and is capable of producing a large phase shift for the propagating coherent light. For a linearly polarized He-Ne laser (λ=633 nm), an electrically commanded phase shift as large as π/2 can be obtained by the large-droplet region of the film. The electrically produced phase shift and its spatial profile controlled by the thickness of the gradient PDLC single layers of large nematic droplets can be useful for tunable spatial light modulators and other devices for active control of laser light. PMID:21629309

  1. Wetted foam liquid fuel ICF target experiments

    DOE PAGESBeta

    Olson, R. E.; Leeper, R. J.; Yi, S. A.; Kline, J. L.; Zylstra, A. B.; Peterson, R. R.; Shah, R.; Braun, T.; Biener, J.; Kozioziemski, B. J.; et al

    2016-05-01

    We are developing a new NIF experimental platform that employs wetted foam liquid fuel layer ICF capsules. We will use the liquid fuel layer capsules in a NIF sub-scale experimental campaign to explore the relationship between hot spot convergence ratio (CR) and the predictability of hot spot formation. DT liquid layer ICF capsules allow for flexibility in hot spot CR via the adjustment of the initial cryogenic capsule temperature and, hence, DT vapor density. Our hypothesis is that the predictive capability of hot spot formation is robust and 1D-like for a relatively low CR hot spot (CR~15), but will becomemore » less reliable as hot spot CR is increased to CR>20. Simulations indicate that backing off on hot spot CR is an excellent way to reduce capsule instability growth and to improve robustness to low-mode x-ray flux asymmetries. In the initial experiments, we will test our hypothesis by measuring hot spot size, neutron yield, ion temperature, and burn width to infer hot spot pressure and compare to predictions for implosions with hot spot CR's in the range of 12 to 25. Larger scale experiments are also being designed, and we will advance from sub-scale to full-scale NIF experiments to determine if 1D-like behavior at low CR is retained as the scale-size is increased. The long-term objective is to develop a liquid fuel layer ICF capsule platform with robust thermonuclear burn, modest CR, and significant α-heating with burn propagation.« less

  2. Wetted foam liquid fuel ICF target experiments

    NASA Astrophysics Data System (ADS)

    Olson, R. E.; Leeper, R. J.; Yi, S. A.; Kline, J. L.; Zylstra, A. B.; Peterson, R. R.; Shah, R.; Braun, T.; Biener, J.; Kozioziemski, B. J.; Sater, J. D.; Biener, M. M.; Hamza, A. V.; Nikroo, A.; Berzak Hopkins, L.; Ho, D.; LePape, S.; Meezan, N. B.

    2016-05-01

    We are developing a new NIF experimental platform that employs wetted foam liquid fuel layer ICF capsules. We will use the liquid fuel layer capsules in a NIF sub-scale experimental campaign to explore the relationship between hot spot convergence ratio (CR) and the predictability of hot spot formation. DT liquid layer ICF capsules allow for flexibility in hot spot CR via the adjustment of the initial cryogenic capsule temperature and, hence, DT vapor density. Our hypothesis is that the predictive capability of hot spot formation is robust and 1D-like for a relatively low CR hot spot (CR∼15), but will become less reliable as hot spot CR is increased to CR>20. Simulations indicate that backing off on hot spot CR is an excellent way to reduce capsule instability growth and to improve robustness to low-mode x-ray flux asymmetries. In the initial experiments, we will test our hypothesis by measuring hot spot size, neutron yield, ion temperature, and burn width to infer hot spot pressure and compare to predictions for implosions with hot spot CR's in the range of 12 to 25. Larger scale experiments are also being designed, and we will advance from sub-scale to full-scale NIF experiments to determine if 1D-like behavior at low CR is retained as the scale-size is increased. The long-term objective is to develop a liquid fuel layer ICF capsule platform with robust thermonuclear burn, modest CR, and significant α-heating with burn propagation.

  3. Modeling Droplet Motion on Liquid-Infused Surface Using Lattice Boltzmann Method

    NASA Astrophysics Data System (ADS)

    Zhao, Mingfei; Yong, Xin

    2015-11-01

    Understanding self-assembly of nanoparticles driven by the evaporation of the particle-covered sacrificial liquid mass dispensed on a solid substrate is of technological important for various printing and deposition techniques. Although the convective deposition of suspended nanoparticles (known as the coffee ring effect) has been studied extensively, the self-assembly of nanoparticles directly delivered to the liquid-gas interface remains unexplored. In this work, we develop a hybrid model that combines free-energy multiphase LBM with Lagrangian particle tracking method to reveal the complex interplay between nanoparticles, convective flow in liquid, and the dynamics of three-phase contact line on the substrate. We first verify our computational model using existing computational and experimental results. We then investigate the evaporation phenomena of a particle-covered droplet with specified nanoparticle distributions and wetting properties. By controlling the boundary conditions, we can implement desired contact angle hysteresis on the substrate that matches experiment observations. This study provides a theoretical framework to explore the dynamics of nanoparticle self-assembly at evaporating liquid-vapor interfaces.

  4. Flow-focusing generation of monodisperse water droplets wrapped by ionic liquid on microfluidic chips: from plug to sphere.

    PubMed

    Wang, Wei-Han; Zhang, Zhi-Ling; Xie, Ya-Ni; Wang, Li; Yi, Song; Liu, Kan; Liu, Jia; Pang, Dai-Wen; Zhao, Xing-Zhong

    2007-11-01

    Generating droplets via microfluidic chips is a promising technology in microanalysis and microsynthesis. To realize room-temperature ionic liquid (IL)-water two-phase studies in microscale, a water-immiscible IL was employed as the continuous phase for the first time to wrap water droplets (either plugs or spheres) on flow-focusing microfluidic chips. The IL, 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]), could wet both hydrophilic and hydrophobic channel surfaces because of its dual role of hydrophilicity/hydrophobicity and extremely high viscosity, thus offering the possibility of wrapping water droplets in totally hydrophilic (THI), moderately hydrophilic (MHI), and hydrophobic (HO) channels. The droplet shape could be tuned from plug to sphere, with the volume from 6.3 nL to 65 pL, by adding an orifice in the focusing region, rendering the hydrophilic channel surface hydrophobic, and suppressing the Uw/UIL ratio below 1.0. Three different breakup processes were defined and clarified, in which the sub-steady breakup and steady breakup were essential for the formation of plugs and spheric droplets, respectively. The influences of channel hydrophilicity/hydrophobicity on droplet formation were carefully studied by evaluating the wetting abilities of water and IL on different surfaces. The superiority of IL over water in wetting hydrophobic surface led to the tendency of forming small, spheric aqueous droplets in the hydrophobic channel. This IL-favored droplet-based system represented a high efficiency in water/IL extraction, in which rhodamine 6G was extracted from aqueous droplets to [BMIM][PF6] in the hydrophobic orifice-included (HO-OI) channel in 0.51 s. PMID:17918864

  5. Drying, phase separation, and deposition in droplets of sunset yellow chromonic liquid crystal

    NASA Astrophysics Data System (ADS)

    Gross, Adam; Davidson, Zoey S.; Huang, Yongyang; Still, Tim; Zhou, Chao; Yodh, A. G.

    We investigate the drying process and the final deposition patterns of multi-phase sessile droplets containing aqueous lyotropic chromonic liquid crystal (LC). The experiments employ a variety of optical techniques including profilometry, polarization optical microscopy and optical coherence microscopy. An unusual hierarchical LC assembly is observed during drying; in particular, LC mesogens are first formed at the start of drying and then compartments of isotropic, nematic and columnar phases arise. Nonuniform evaporation creates concentration gradients in droplets such that LC phases emerge from the outer edge of the drop and advance to the center over the course of drying. Distinct outward flows associated with the ``coffee-ring effect'' are seen initially, but the assembly of the mesogens creates viscosity, density, and surface tension gradients that effectively introduce new convective flows and complex LC phase boundaries within the drop. Finally, we show that the final deposit shape of chromonic materials changes with rate of evaporation. We gratefully acknowledge financial support through NSF DMR12-05463, MRSEC DMR11-20901, NASA NNX08AO0G, and NSF DBI-1455613.

  6. Effect of liquid droplets on turbulence in a round gaseous jet

    NASA Technical Reports Server (NTRS)

    Mostafa, A. A.; Elghobashi, S. E.

    1986-01-01

    The main objective of this investigation is to develop a two-equation turbulence model for dilute vaporizing sprays or in general for dispersed two-phase flows including the effects of phase changes. The model that accounts for the interaction between the two phases is based on rigorously derived equations for turbulence kinetic energy (K) and its dissipation rate epsilon of the carrier phase using the momentum equation of that phase. Closure is achieved by modeling the turbulent correlations, up to third order, in the equations of the mean motion, concentration of the vapor in the carrier phase, and the kinetic energy of turbulence and its dissipation rate for the carrier phase. The governing equations are presented in both the exact and the modeled formes. The governing equations are solved numerically using a finite-difference procedure to test the presented model for the flow of a turbulent axisymmetric gaseous jet laden with either evaporating liquid droplets or solid particles. The predictions include the distribution of the mean velocity, volume fractions of the different phases, concentration of the evaporated material in the carrier phase, turbulence intensity and shear stress of the carrier phase, droplet diameter distribution, and the jet spreading rate. The predictions are in good agreement with the experimental data.

  7. Periodic emission of droplets from an oscillating electrified meniscus of a low-viscosity, highly conductive liquid

    NASA Astrophysics Data System (ADS)

    Hijano, A. J.; Loscertales, I. G.; Ibáñez, S. E.; Higuera, F. J.

    2015-01-01

    The generation of identical droplets of controllable size in the micrometer range is a problem of much interest owing to the numerous technological applications of such droplets. This work reports an investigation of the regime of periodic emission of droplets from an electrified oscillating meniscus of a liquid of low viscosity and high electrical conductivity attached to the end of a capillary tube, which may be used to produce droplets more than ten times smaller than the diameter of the tube. To attain this periodic microdripping regime, termed axial spray mode II by Juraschek and Röllgen [R. Juraschek and F. W. Röllgen, Int. J. Mass Spectrom. 177, 1 (1998), 10.1016/S1387-3806(98)14025-3], liquid is continuously supplied through the tube at a given constant flow rate, while a dc voltage is applied between the tube and a nearby counter electrode. The resulting electric field induces a stress at the surface of the liquid that stretches the meniscus until, in certain ranges of voltage and flow rate, it develops a ligament that eventually detaches, forming a single droplet, in a process that repeats itself periodically. While it is being stretched, the ligament develops a conical tip that emits ultrafine droplets, but the total mass emitted is practically contained in the main droplet. In the parametrical domain studied, we find that the process depends on two main dimensionless parameters, the flow rate nondimensionalized with the diameter of the tube and the capillary time, q , and the electric Bond number BE, which is a nondimensional measure of the square of the applied voltage. The meniscus oscillation frequency made nondimensional with the capillary time, f , is of order unity for very small flow rates and tends to decrease as the inverse of the square root of q for larger values of this parameter. The product of the meniscus mean volume times the oscillation frequency is nearly constant. The characteristic length and width of the liquid ligament

  8. Jumping liquid metal droplet in electrolyte triggered by solid metal particles

    NASA Astrophysics Data System (ADS)

    Tang, Jianbo; Wang, Junjie; Liu, Jing; Zhou, Yuan

    2016-05-01

    We report the electron discharge effect due to point contact between liquid metal and solid metal particles in electrolyte. Adding nickel particles induces drastic hydrogen generating and intermittent jumping of a sub-millimeter EGaIn droplet in NaOH solution. Observations from different orientations disclose that such jumping behavior is triggered by pressurized bubbles under the assistance of interfacial interactions. Hydrogen evolution around particles provides clear evidence that such electric instability originates from the varied electric potential and morphology between the two metallic materials. The point-contact-induced charge concentration significantly enhances the near-surface electric field intensity at the particle tips and thus causes electric breakdown of the electrolyte.

  9. Simulation of a liquid droplet ejection device using multi-actuator

    NASA Astrophysics Data System (ADS)

    Ono, Yoshihiro; Yoshino, Michitaka; Yasuda, Akira; Tanuma, Chiaki

    2016-07-01

    An equivalent circuit model for a liquid droplet ejection device using a multiactuator has been developed. The equivalent circuit was simplified using a gyrator in the synthesis of the outputs of many elements. The simulation was performed for an inkjet head having three piezoelectric elements using MATLAB/Simulink. In this model, the pressure chamber is filled with a Newtonian fluid. For this reason, the model assumed only the resistance component of the pressure chamber and the nozzle as a load. Furthermore, since the resistance component of the inlet is much larger than that of the nozzle, it is not considered in this model. As a result, by providing a time difference between the driving signals of the piezoelectric elements, we found that the pressure of the ink chamber could be arbitrarily controlled. By this model, it becomes possible to control the pressure in the ink chamber of the inkjet head required for the ejection of various inks.

  10. USC/AIAA student get away special project liquid droplet collector experiment

    NASA Technical Reports Server (NTRS)

    Levesque, Raymond J., II

    1987-01-01

    This experimental payload was developed in order to observe, in a micro-gravity vacuum environment, the characteristics and stability of a thin fluid film flowing across a slightly curved surface. The test apparatus was designed based upon various ground-based thin film investigations, combined with the constraints imposed by the rigors of launch and the space environment. Testing of the fluid test article at atmospheric pressure and in vacuum verified the design provisions employed concerning ultra-low inlet pressure pump construction, as well as confirming expected pressure losses in the system. During the course of hardware development and construction modifications were required; however, the overall payload configuration remained largely unchanged. This will allow for modification and reflight of the apparatus based upon the findings of the initial flight. The specific applications of this experiment include Liquid Droplet Radiator development and various forms of material transport in vacuum.

  11. Electrowetting on liquid-infused film (EWOLF): Complete reversibility and controlled droplet oscillation suppression for fast optical imaging

    PubMed Central

    Hao, Chonglei; Liu, Yahua; Chen, Xuemei; He, Yuncheng; Li, Qiusheng; Li, K. Y.; Wang, Zuankai

    2014-01-01

    Electrowetting on dielectric (EWOD) has emerged as a powerful tool to electrically manipulate tiny individual droplets in a controlled manner. Despite tremendous progress over the past two decades, current EWOD operating in ambient conditions has limited functionalities posing challenges for its applications, including electronic display, energy generation, and microfluidic systems. Here, we demonstrate a new paradigm of electrowetting on liquid-infused film (EWOLF) that allows for complete reversibility and tunable transient response simultaneously. We determine that these functionalities in EWOLF are attributed to its novel configuration, which allows for the formation of viscous liquid-liquid interfaces as well as additional wetting ridges, thereby suppressing the contact line pinning and severe droplet oscillation encountered in the conventional EWOD. Finally, by harnessing these functionalities demonstrated in EWOLF, we also explore its application as liquid lens for fast optical focusing. PMID:25355005

  12. Two Droplets on Wire Approaching Ignition

    NASA Technical Reports Server (NTRS)

    2003-01-01

    The Fiber-Supported Droplet Combustion (FSDC) uses two droplets positioned on the fiber wire, instead of the usual one. Two droplets more closely simulates the environment in engines, which ignite many fuel droplets at once. The behavior of the burning was also unexpected -- the droplets moved together after ignition, generating quite a bit of data for understanding the interaction of fuel droplets while they burn. This MPEG movie (1.3 MB) shows a time-lapse of this burn (3x speed). Because FSDC is backlit (the bright glow behind the drops), you carnot see the glow of the droplets while they burn -- instead, you see them shrink! The small blobs left on the wire after the burn are the beads used to center the fuel droplet on the wire. This image was taken on STS-94, July 12, 1997, MET:10/19:13 (approximate). FSDC-2 studied fundamental phenomena related to liquid fuel droplet combustion in air. Pure fuels and mixtures of fuels were burned as isolated single and dual droplets with and without forced air convection. The FSDC guest investigator was Forman Williams, University of California, San Diego. The experiment was part of the space research investigations conducted during the Microgravity Science Laboratory-1R mission (STS-94, July 1-17 1997). Advanced combustion experiments will be a part of investigations planned for the International Space Station. (1.3MB, 12-second MPEG, screen 320 x 240 pixels; downlinked video, higher quality not available) A still JPG composite of this movie is available at http://mix.msfc.nasa.gov/ABSTRACTS/MSFC-0300178.html.

  13. Analysis of small droplets with a new detector for liquid chromatography based on laser-induced breakdown spectroscopy

    NASA Astrophysics Data System (ADS)

    Janzen, Christoph; Fleige, Rüdiger; Noll, Reinhard; Schwenke, Heinrich; Lahmann, Wilhelm; Knoth, Joachim; Beaven, Peter; Jantzen, Eckard; Oest, Andreas; Koke, Peter

    2005-08-01

    The miniaturization of analytical techniques is a general trend in speciation analytics. We have developed a new analytical technique combining high pressure liquid chromatography (HPLC) with laser-induced breakdown spectroscopy (LIBS). This enables a molecule-specific separation followed by an element-specific analysis of smallest amounts of complex samples. The liquid flow coming from a HPLC pump is transformed into a continuous stream of small droplets (diameter 50-100 μm, volume 65-500 pl) using a piezoelectric pulsed nozzle. After the detection of single droplets with a droplet detector, a Q-switched Nd:YAG Laser is triggered to emit a synchronized laser pulse that irradiates a single droplet. The droplets are evaporated and transformed to the plasma state. The spectrum emitted from the plasma is collected by a spherical mirror and directed through the entrance slit of a Paschen-Runge spectrometer equipped with channel photomultipliers. The spectrometer detects 31 elements simultaneously covering a spectral range from 120 to 589 nm. Purging the measurement chamber with argon enables the detection of vacuum-UV lines. Since the sample is transferred to the plasma state without dilution, very low flow rates in the sub-μl/min range can be realised.

  14. Distillation of liquid fuels by thermogravimetry

    SciTech Connect

    Huang, He; Wang, Keyu; Wang, Shaojie; Klein, M.T.; Calkins, W.H.

    1996-12-31

    In this paper, design and operation of a custom-built thermogravimetric apparatus for the distillation of liquid fuels are reported. Using a sensitive balance with scale of 0.001 g and ASTM distillation glassware, several petroleum and petroleum-derived samples have been analyzed by the thermogravimetric distillation method. When the ASTM distillation glassware is replaced by a micro-scale unit, sample size could be reduced from 100 g to 5-10 g. A computer program has been developed to transfer the data into a distillation plot, e.g. Weight Percent Distilled vs. Boiling Point. It also generates a report on the characteristic distillation parameters, such as, IBP (Initial Boiling Point), FBP (Final Boiling Point), and boiling point at 50 wt% distilled. Comparison of the boiling point distributions determined by TG (thermogravimetry) with those by SimDis GC (Simulated-Distillation Gas Chromatography) on two liquid fuel samples (i.e. a decanted oil and a filtered crude oil) are also discussed in this paper.

  15. Silver halide fiber-based evanescent-wave liquid droplet sensing with room temperature mid-infrared quantum cascade lasers.

    PubMed

    Chen, J; Liu, Z; Gmachl, C; Sivco, D

    2005-08-01

    Quantum cascade lasers and unclad silver halide fibers were used to assemble mid-infrared fiber-optics evanescent-wave sensors suitable to measure the chemical composition of liquid droplets. The laser wavelengths were chosen to be in the regions which offer the largest absorption contrast between constituents inside the mixture droplets. A pseudo-Beer-Lambert law fits well with the experimental data. Using a 300microm diameter fiber with a 25 mm immersion length, the signal to noise ratios correspond to 1 vol.% for alpha-tocophenol in squalane and 2 vol.% for acetone in aqueous solution for laser wavenumbers of 1208 cm-1 and 1363 cm-1, respectively.

  16. Liquid-vapor isotherm in a closed single-component system with droplets or bubbles in smooth crevices.

    PubMed

    Lago, Marcelo; Martin, Rafael; Araujo, Mariela

    2003-11-15

    A thermodynamic model in order to study a single-component system where droplets or bubbles are inside smooth crevices is presented. Liquid-vapor interface curvature radius can change its sign as the droplet or bubble volume change. The results suggest that there is always dispersed phase inside smooth crevices of microscopic dimensions, even in the expected single-phase region. Thus, the occurrence of an anti-ripening phenomenon is predicted from a microscopic point of view; meanwhile the occurrence of a ripening phenomenon is energetically favorable at a macroscopic scale. The relevance of these results on the heterogeneous nucleation process is analyzed. PMID:14583222

  17. Determination of parabens in beverage samples by dispersive liquid-liquid microextraction based on solidification of floating organic droplet.

    PubMed

    Hou, Fang; Deng, Xiaoying; Jiang, Xinyu; Yu, Jingang

    2014-01-01

    A simple and efficient method for dispersive liquid-liquid microextraction of methylparaben, ethylparaben, propylparaben and butylparaben in real beverage samples was developed. It is making use of solidified floating organic droplets of 1-dodecanol which has low density and a proper melting point. Parameters influencing the extraction efficiency, such as the type of extraction and dispersive solvent, the volume of extraction and dispersive solvent, salt effect, pH, extraction time, were optimized and resulted in enrichment factors (EFs) of 84 for methylparaben, 103 for ethylparaben, 115 for propylparaben and 126 for butylparaben. The limits of detection for parabens were 1.52, 1.06, 0.32 and 0.17 ng/mL, respectively. Excellent linearity with coefficients of correlation from 0.9970 to 0.9997 was observed in the concentration range of 5-1,000 ng/mL. The repeatability of the proposed method expressed as relative standard deviations (RSDs) ranged from 2.54 to 3.89% (n = 5). The relative recoveries for parabens in beverage samples were good and in the ranges of 89.8-109.9, 90.2-107.3, 90.9-101.7 and 92.3-118.1%, respectively. Thus, the proposed method has excellent potential for the determination of parabens in beverage samples.

  18. Instability of nano- and microscale liquid metal filaments: Transition from single droplet collapse to multidroplet breakup

    DOE PAGESBeta

    Hartnett, Chris A.; Mahady, Kyle; Fowlkes, Jason Davidson; Afkhami, Shahriar; Rack, P. D.; Kondic, L.

    2015-11-23

    We carry out experimental and numerical studies to investigate the collapse and breakup of finite size, nano- and microscale, liquid metal filaments supported on a substrate. We find the critical dimensions below which filaments do not break up but rather collapse to a single droplet. The transition from collapse to breakup can be described as a competition between two fluid dynamic phenomena: the capillary driven end retraction and the Rayleigh–Plateau type instability mechanism that drives the breakup. We focus on the unique spatial and temporal transition region between these two phenomena using patterned metallic thin film strips and pulsed-laser-induced dewetting.more » The experimental results are compared to an analytical model proposed by Driessen et al. and modified to include substrate interactions. Additionally, we report the results of numerical simulations based on a volume-of-fluid method to provide additional insight and highlight the importance of liquid metal resolidification, which reduces inertial effects.« less

  19. The wall shear force on a liquid droplet adhering to a solid surface under an imposed shear

    NASA Astrophysics Data System (ADS)

    Shabtay, Royi; Frankel, Itzchak

    2011-11-01

    We focus on large droplet viscosities typical of those appearing in the upper respiratory tract of CF or chronically ventilated patients. To further simplify the problem we assume vanishingly small capillary numbers and consider (non-deformable) hemispherical droplets. Under these assumptions the problem decouples into (i) the external problem of imposed shear flow over a planar solid wall with a hemispherical protuberance which is simulated by means of a commercially available finite - volume code and (ii) the inner Stokes flow animated by the now prescribed shear stress distribution over the liquid surface. The latter problem is addressed through use of series expansions in spherical harmonics. The interaction between the caterpillar inner - fluid motion and the solid substrate results in a shear force adding to the external - flow drag force acting in the downstream direction. Throughout the range of outer - flow Reynolds numbers considered (0.05-50) this interaction contributes over 35% of the total hydrodynamic force acting to dislodge the droplet.

  20. Uranium droplet nuclear reactor core with MHD generator

    NASA Astrophysics Data System (ADS)

    Anghaie, Samim; Kumar, Ratan

    An innovative concept employing liquid uranium droplets as fuel in an ultrahigh-temperature vapor core reactor (UTVR) magnetohydrodynamic (MHD) generator power system for space power generation has been studied. Metallic vapor in superheated form acts as a working fluid for a closed-Rankine-type thermodynamic cycle. Usage of fuel and working fluid in this form assures certain advantages. The major technical issues emerging as a result involve a method for droplet generation, droplet transport in the reactor core, heat generation in the fuel and transport to the metallic vapor, and materials compatibility. A qualitative and quantitative attempt to resolve these issues has indicated the promise and tentative feasibility of the system.

  1. Conceptual design for a kerosene fuel-rich gas-generator of a turbopump-fed liquid rocket engine

    NASA Astrophysics Data System (ADS)

    Son, Min; Koo, Jaye; Cho, Won Kook; Lee, Eun Seok

    2012-10-01

    A design method for a kerosene fuel-rich gas-generator of a liquid rocket engine using turbopumps to supply propellant was performed at a conceptual level. The gas-generator creates hot gases, enabling the turbine to operate the turbopumps. A chemical non-equilibrium analysis and a droplet vaporization model were used for the estimation of the burnt gas properties and characteristic chamber length. A premixed counter-flow flame analysis was performed for the prediction of the burnt gas properties, namely the temperature, the specific heat ratio and heat capacity, and the chemical reaction time. To predict the vaporization time, the Spalding model, using a single droplet in convective condition, was used. The minimum residence time in the chamber and the characteristic length were calculated by adding the reaction time and the vaporization time. Using the characteristic length, the design methods for the fuel-rich gas-generator were established. Finally, a parametric study was achieved for the effects of the O/F ratio, mass flow rate, chamber pressure, initial droplet temperature, initial droplet diameter and initial droplet velocity.

  2. Liquid Metal Droplet and Micro Corrugated Diaphragm RF-MEMS for reconfigurable RF filters

    NASA Astrophysics Data System (ADS)

    Irshad, Wasim

    detail and have proved pivotal to this work. The second part of the dissertation focuses on the Liquid Metal Droplet RF-MEMS. A novel tunable RF MEMS resonator that is based upon electrostatic control over the morphology of a liquid metal droplet (LMD) is conceived. We demonstrate an LMD evanescent-mode cavity resonator that simultaneously achieves wide analog tuning from 12 to 18 GHz with a measured quality factor of 1400-1840. A droplet of 250-mum diameter is utilized and the applied bias is limited to 100 V. This device operates on a principle called Electro-Wetting On Dielectric (EWOD). The liquid metal employed is a non-toxic eutectic alloy of Gallium, Indium and Tin known as Galinstan. This device also exploits interfacial surface energy and viscous body forces that dominate at nanoliter scale. We then apply our Liquid Metal Droplet (LMD) RF-MEMS architecture to demonstrate a continuously tunable electrostatic Ku-Band Filter. A 2-pole bandpass filter with measured insertion loss of less than 0.4dB and 3dB FBW of 3.4% is achieved using a Galinstan droplet of 250mum diameter and bias limited to 100V. We demonstrate that the LMD is insensitive to gravity by performing inversion and tilt experiments. In addition, we study its thermal tolerance by subjecting the LMD up to 150° C. The third part of the dissertation is dedicated to the Micro-Corrugated Diaphragm (MCD) RF-MEMS. We present an evanescent-mode cavity bandpass filter with state-of-the-art RF performance metrics like 4:1 tuning ratio from 5 to 20 GHz with less than 2dB insertion loss and 2-6% 3dB bandwidth. Micro-Corrugated Diaphragm (MCD) is a novel electrostatic MEMS design specifically engineered to provide large-scale analog deflections necessary for such continuous and wide tunable filtering with very high quality factor. We demonstrate a 1.25mm radius and 2mum thick Gold MCD which provides 30mum total deflection with nearly 60% analog range. We also present a detailed and systematic MCD design

  3. Liquid Fuels and Natural Gas in the Americas

    EIA Publications

    2014-01-01

    The Energy Information Administration's (EIA) Liquid Fuels and Natural Gas in the Americas report, published today, is a Congressionally-requested study examining the energy trends and developments in the Americas over the past decade. The report focuses on liquid fuels and natural gas—particularly reserves and resources, production, consumption, trade, and investment—given their scale and significance to the region.

  4. Low Emissions Burner Technology for Metal Processing Industry using Byproducts and Biomass Derived Liquid Fuels

    SciTech Connect

    Agrawal, Ajay; Taylor, Robert

    2013-09-30

    This research and development efforts produced low-emission burner technology capable of operating on natural gas as well as crude glycerin and/or fatty acids generated in biodiesel plants. The research was conducted in three stages (1) Concept definition leading to the design and development of a small laboratory scale burner, (2) Scale-up to prototype burner design and development, and (3) Technology demonstration with field vefiication. The burner design relies upon the Flow Blurring (FB) fuel injection based on aerodynamically creating two-phase flow near the injector exit. The fuel tube and discharge orifice both of inside diameter D are separated by gap H. For H < 0.25D, the atomizing air bubbles into liquid fuel to create a two-phase flow near the tip of the fuel tube. Pressurized two-phase fuel-air mixture exits through the discharge orifice, which results in expansion and breakup of air bubbles yielding a spray with fine droplets. First, low-emission combustion of diesel, biodiesel and straight VO (soybean oil) was achieved by utilizing FB injector to yield fine sprays for these fuels with significantly different physical properties. Visual images for these baseline experiments conducted with heat release rate (HRR) of about 8 kW illustrate clean blue flames indicating premixed combustion for all three fuels. Radial profiles of the product gas temperature at the combustor exit overlap each other signifying that the combustion efficiency is independent of the fuel. At the combustor exit, the NOx emissions are within the measurement uncertainties, while CO emissions are slightly higher for straight VO as compared to diesel and biodiesel. Considering the large variations in physical and chemical properties of fuels considered, the small differences observed in CO and NOx emissions show promise for fuel-flexible, clean combustion systems. FB injector has proven to be very effective in atomizing fuels with very different physical properties, and it offers a

  5. Conversion of olefins to liquid motor fuels

    DOEpatents

    Rabo, Jule A.; Coughlin, Peter K.

    1988-01-01

    Linear and/or branched claim C.sub.2 to C.sub.12 olefins are converted to hydrocarbon mixtures suitable for use as liquid motor fuels by contact with a catalyst capable of ensuring the production of desirable products with only a relatively minor amount of heavy products boiling beyond the diesel oil range. The catalyst having desirable stability during continuous production operations, comprises a steam stabilized zeolite Y catalyst of hydrophobic character, desirably in aluminum-extracted form. The olefins such as propylene, may be diluted with inerts, such as paraffins or with water, the latter serving to moderate the acidity of the catalyst, or to further moderate the activity of the aluminum-extracted catalyst, so as to increase the effective life of the catalyst.

  6. Biomass gasification for liquid fuel production

    SciTech Connect

    Najser, Jan E-mail: vaclav.peer@vsb.cz; Peer, Václav E-mail: vaclav.peer@vsb.cz

    2014-08-06

    In our old fix-bed autothermal gasifier we tested wood chips and wood pellets. We make experiments for Czech company producing agro pellets - pellets made from agricultural waste and fastrenewable natural resources. We tested pellets from wheat and rice straw and hay. These materials can be very perspective, because they dońt compete with food production, they were formed in sufficient quantity and in the place of their treatment. New installation is composed of allothermal biomass fixed bed gasifier with conditioning and using produced syngas for Fischer - Tropsch synthesis. As a gasifying agent will be used steam. Gas purification will have two parts - separation of dust particles using a hot filter and dolomite reactor for decomposition of tars. In next steps, gas will be cooled, compressed and removed of sulphur and chlorine compounds and carbon dioxide. This syngas will be used for liquid fuel synthesis.

  7. Biological production of liquid fuels from biomass

    SciTech Connect

    1982-01-01

    A scheme for the production of liquid fuels from renewable resources such as poplar wood and lignocellulosic wastes from a refuse hydropulper was investigated. The particular scheme being studied involves the conversion of a cellulosic residue, resulting from a solvent delignified lignocellulosic feed, into either high concentration sugar syrups or into ethyl and/or butyl alcohol. The construction of a pilot apparatus for solvent delignifying 150 g samples of lignocellulosic feeds was completed. Also, an analysis method for characterizing the delignified product has been selected and tested. This is a method recommended in the Forage Fiber Handbook. Delignified samples are now being prepared and tested for their extent of delignification and susceptibility to enzyme hydrolysis. Work is continuing on characterizing the cellulase and cellobiase enzyme systems derived from the YX strain of Thermomonospora.

  8. Biomass gasification for liquid fuel production

    NASA Astrophysics Data System (ADS)

    Najser, Jan; Peer, Václav; Vantuch, Martin

    2014-08-01

    In our old fix-bed autothermal gasifier we tested wood chips and wood pellets. We make experiments for Czech company producing agro pellets - pellets made from agricultural waste and fastrenewable natural resources. We tested pellets from wheat and rice straw and hay. These materials can be very perspective, because they dońt compete with food production, they were formed in sufficient quantity and in the place of their treatment. New installation is composed of allothermal biomass fixed bed gasifier with conditioning and using produced syngas for Fischer - Tropsch synthesis. As a gasifying agent will be used steam. Gas purification will have two parts - separation of dust particles using a hot filter and dolomite reactor for decomposition of tars. In next steps, gas will be cooled, compressed and removed of sulphur and chlorine compounds and carbon dioxide. This syngas will be used for liquid fuel synthesis.

  9. Droplet transport system and methods

    NASA Technical Reports Server (NTRS)

    Neitzel, G. Paul (Inventor)

    2010-01-01

    Embodiments of droplet transport systems and methods are disclosed for levitating and transporting single or encapsulated droplets using thermocapillary convection. One method embodiment, among others comprises providing a droplet of a first liquid; and applying thermocapillary convection to the droplet to levitate and move the droplet.

  10. Fuel gas production by microwave plasma in liquid

    SciTech Connect

    Nomura, Shinfuku; Toyota, Hiromichi; Tawara, Michinaga; Yamashita, Hiroshi; Matsumoto, Kenya

    2006-06-05

    We propose to apply plasma in liquid to replace gas-phase plasma because we expect much higher reaction rates for the chemical deposition of plasma in liquid than for chemical vapor deposition. A reactor for producing microwave plasma in a liquid could produce plasma in hydrocarbon liquids and waste oils. Generated gases consist of up to 81% hydrogen by volume. We confirmed that fuel gases such as methane and ethylene can be produced by microwave plasma in liquid.

  11. Moving Liquids with Sound: The Physics of Acoustic Droplet Ejection for Robust Laboratory Automation in Life Sciences.

    PubMed

    Hadimioglu, Babur; Stearns, Richard; Ellson, Richard

    2016-02-01

    Liquid handling instruments for life science applications based on droplet formation with focused acoustic energy or acoustic droplet ejection (ADE) were introduced commercially more than a decade ago. While the idea of "moving liquids with sound" was known in the 20th century, the development of precise methods for acoustic dispensing to aliquot life science materials in the laboratory began in earnest in the 21st century with the adaptation of the controlled "drop on demand" acoustic transfer of droplets from high-density microplates for high-throughput screening (HTS) applications. Robust ADE implementations for life science applications achieve excellent accuracy and precision by using acoustics first to sense the liquid characteristics relevant for its transfer, and then to actuate transfer of the liquid with customized application of sound energy to the given well and well fluid in the microplate. This article provides an overview of the physics behind ADE and its central role in both acoustical and rheological aspects of robust implementation of ADE in the life science laboratory and its broad range of ejectable materials.

  12. Modelling of the process of fragmentation and vaporization of non-reacting liquid droplets in high-enthalpy gas flows

    NASA Astrophysics Data System (ADS)

    Arefyev, K. Yu.; Voronetsky, A. V.

    2015-09-01

    The intensification of the fragmentation and vaporization of liquid droplets in two-phase flows with the gas stagnation temperature Tg = 800-2500 K is an important scientific and technological problem. One should note that despite a high practical importance the mechanism of the vaporization of droplets with their preliminary gas-dynamic fragmentation in high-enthalpy flows has been studied insufficiently completely and requires additional research. The paper presents a mathematical model and the results of the computations of the fragmentation and vaporization of liquid droplets in subsonic and supersonic flows with a high stagnation temperature. A comparison of the obtained data with the experiments of other authors has been done. The extension of the regions of the gas-dynamic fragmentation and droplet vaporization in flow ducts with a variable distribution of parameters has been estimated. The found peculiarities may be used at the design of energy installations of the promising samples of the aerospace technology and gas-dynamic pipes.

  13. Analysis of the effects of evaporative cooling on the evaporation of liquid droplets using a combined field approach

    PubMed Central

    Xu, Xuefeng; Ma, Liran

    2015-01-01

    During liquid evaporation, the equations for the vapor concentration in the atmosphere and for the temperature in the liquid are coupled and must be solved in an iterative manner. In the present paper, a combined field approach which unifies the coupled fields into one single hybrid field and thus makes the iteration unnecessary is proposed. By using this approach, the influences of the evaporative cooling on the evaporation of pinned sessile droplets are investigated, and its predictions are found in good agreement with the previous theoretical and experimental results. A dimensionless number Ec which can evaluate the strength of the evaporative cooling is then introduced, and the results show that both the evaporation flux along the droplet surface and the total evaporation rate of the droplet decrease as the evaporative cooling number Ec increases. For drying droplets, there exists a critical value EcCrit below which the evaporative cooling effect can be neglected and above which the significance of the effect increases dramatically. The present work may also have more general applications to coupled field problems in which all the fields have the same governing equation. PMID:25721987

  14. Liquid transportation fuels from algal oils

    NASA Astrophysics Data System (ADS)

    Chen, Daichuan

    Liquid transportation fuels from renewable sources are becoming more prominent and important in modem society. Processing of hydrocarbon oils from algae has not been studied in detail in the past, so components which have been proposed for incorporation in algal oils via genetic engineering, such as cuparene, farnesene, phytol and squalene, have been subjected to processing via catalytic cracking in a pulse reactor at different temperatures. The cracking results showed that liquid products contained numerous high octane molecules which make it feasible for use in automobiles. Additionally, canola oil, chosen as an algal oil model compound, was studied as a feed for catalytic cracking in a fixed-bed reactor at atmospheric pressure over different types of zeolites. The results showed that MFI catalysts gave the highest yield of gasoline range products and lowest coke formation. Gallium loaded MFI zeolites increased the total aromatics yield for the canola oil cracking relative to the acid form of the zeolite. Finally, algal oils were cracked on several selected zeolites, and the results showed the same trend as canola oil cracking. MFI gave the highest gasoline yield (43.8 wt%) and lowest coke (4.7 wt%). The total aromatics yield from algae oil cracking is improved 7.8 wt% when MFI is loaded with gallium.

  15. Formulating liquid hydrocarbon fuels for SOFCs

    NASA Astrophysics Data System (ADS)

    Saunders, G. J.; Preece, J.; Kendall, K.

    The injection of liquid hydrocarbons directly into an SOFC system is considered for application to hybrid vehicles. The main problem is carbon deposition on the nickel anode when molecules such as ethanol or iso-octane are injected directly. Such carbon deposition has been studied using a microtubular SOFC with a mass spectrometer analysing the product gases to investigate the reaction sequence and also to investigate the deposited carbon by temperature programmed oxidation (TPO). The results show that only two liquids could be injected directly onto nickel cermet anodes without serious carbon blockage, methanol and methanoic acid. Even then, TPO experiments revealed deposition of small amounts of carbon which could be prevented by small additions of air or water to the fuel. Gasoline type molecules like iso-octane killed the SOFC in about 30 min operation, with about 90% of the molecular carbon being deposited on the nickel cermet anode. However, certain mixtures of iso-octane, water, alcohol and surfactant were found to produce beneficial results with remarkably low carbon deposition, less than 1% of the molecular carbon appearing on the anode. Such formulations had octane numbers appropriate to internal combustion engine operation.

  16. Soot formation during combustion of unsupported methanol/toluene mixture droplets in microgravity

    NASA Technical Reports Server (NTRS)

    Jackson, G. S.; Avedisian, C. T.; Yang, J. C.

    1991-01-01

    Results are reported of an experimental study tracing the influence of liquid composition on soot formation and the burning rate of a droplet composed of a binary miscible mixture of liquids. The mixture components represented a highly sooting fuel, toluene, and a nonsooting fuel, methanol. The toluene concentration in methanol was shown to dramatically influence flame luminosity and soot production. Neither burning rates nor a propensity for flame extinction appeared to be significantly affected by toluene mixture fractions. Five-percent toluene mixture droplets behaved like pure methanol droplets in terms of burning rate, lack of flame luminosity, and extinction. Increasing the toluene concentration in the droplets to 25 percent increased flame luminosity, yet no visible soot agglomerates were observed. The 50-percent-mixture droplets burned with highly luminous flames and large amounts of soot agglomerates collecting inside the flame. All the mixture droplets showed burning rates similar to those of pure methanol and likewise exhibited flame extinction before complete droplet vaporization.

  17. Droplet Suspended on a Wire Begins Ignition

    NASA Technical Reports Server (NTRS)

    2003-01-01

    The Fiber Supported Droplet Combustion Experiment completing a number of successful burns on STS-94, July 11, 1997, MET:9/17:40 (approximate). The photo shows a droplet of 95% heptane and 5% hexadecane, suspended and positioned by the fiber wire, just as it is being ignited by the glowing coil beneath. Study of the physical properties of burning fuel from this experiment is expected to contribute to more efficient use of fossil fuels and reduction of combustion by-products on Earth. The sequence is from a time-lapse movie (34 seconds condensed to 12 seconds), and clearly shows particles emanating from the droplet during the burn. The droplet shrank to nothing as it was consumed. FSDC-2 studied fundamental phenomena related to liquid fuel droplet combustion in air. Pure fuels and mixtures of fuels were burned as isolated single and dual droplets with and without forced air convection. The FSDC guest investigator was Forman Williams, University of California, San Diego. The experiment was part of the space research investigations conducted during the Microgravity Science Laboratory-1R mission (STS-94, July 1-17 1997). Advanced combustion experiments will be a part of investigations plarned for the International Space Station. (1.2 MB, 11-second MPEG, screen 320 x 240 pixels; downlinked video, higher quality not available) A still JPG composite of this movie is available at http://mix.msfc.nasa.gov/ABSTRACTS/MSFC-0300180.html.

  18. Colloidal spheres confined by liquid droplets: Geometry, physics, and physical chemistry

    NASA Astrophysics Data System (ADS)

    Manoharan, Vinothan N.

    2006-09-01

    I discuss how colloidal particles organize when they are confined by emulsion droplets. In these systems, the interplay between surface tension and interparticle repulsion drives the formation of complex, non-crystalline 3D arrangements. These can be classified into three groups: colloidosomes, or Pickering emulsions, structures that form when particles are bound to the interface of a spherical droplet; colloidal clusters, small polyhedral configurations of colloids formed by capillary forces generated in an evaporating emulsion droplet; and supraparticles, ball-shaped crystallites formed in the interior of emulsion droplets. I discuss the preparation, properties, and structure of each of these systems, using relevant results from geometry to describe how the particles organize.

  19. Tactic, reactive, and functional droplets outside of equilibrium.

    PubMed

    Lach, Sławomir; Yoon, Seok Min; Grzybowski, Bartosz A

    2016-08-22

    Under non-equilibrium conditions, liquid droplets coupled to their environment by sustained flows of matter and/or energy can become "active" systems capable of various life-like functions. When "fueled" by even simple chemical reactions, such droplets can become tactic and can perform "intelligent" tasks such as maze solving. With more complex chemistries, droplets can support basic forms of metabolism, grow, self-replicate, and exhibit evolutionary changes akin to biological cells. There are also first exciting examples of active droplets connected into larger, tissue-like systems supporting droplet-to-droplet communication, and giving rise to collective material properties. As practical applications of droplets also begin to appear (e.g., in single-cell diagnostics, new methods of electricity generation, optofluidics, or sensors), it appears timely to review and systematize progress in this highly interdisciplinary area of chemical research, and also think about the avenues (and the roadblocks) for future work.

  20. 26 CFR 48.4041-7 - Dual use of taxable liquid fuel.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 26 Internal Revenue 16 2010-04-01 2010-04-01 true Dual use of taxable liquid fuel. 48.4041-7... taxable liquid fuel. Tax applies to all taxable liquid fuel sold for use or used as a fuel in the motor... liquid fuel sold for this use or so used, whether or not the special equipment is mounted on the...

  1. 26 CFR 48.4041-7 - Dual use of taxable liquid fuel.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 26 Internal Revenue 16 2011-04-01 2011-04-01 false Dual use of taxable liquid fuel. 48.4041-7... taxable liquid fuel. Tax applies to all taxable liquid fuel sold for use or used as a fuel in the motor... liquid fuel sold for this use or so used, whether or not the special equipment is mounted on the...

  2. 26 CFR 48.4041-7 - Dual use of taxable liquid fuel.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 26 Internal Revenue 16 2013-04-01 2013-04-01 false Dual use of taxable liquid fuel. 48.4041-7... taxable liquid fuel. Tax applies to all taxable liquid fuel sold for use or used as a fuel in the motor... liquid fuel sold for this use or so used, whether or not the special equipment is mounted on the...

  3. 26 CFR 48.4041-7 - Dual use of taxable liquid fuel.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 26 Internal Revenue 16 2012-04-01 2012-04-01 false Dual use of taxable liquid fuel. 48.4041-7... taxable liquid fuel. Tax applies to all taxable liquid fuel sold for use or used as a fuel in the motor... liquid fuel sold for this use or so used, whether or not the special equipment is mounted on the...

  4. Classification of the ejection mechanisms of charged macromolecules from liquid droplets

    NASA Astrophysics Data System (ADS)

    Consta, Styliani; Malevanets, Anatoly

    2013-01-01

    The relation between the charge state of a macromolecule and its ejection mechanism from droplets is one of the important questions in electrospray ionization methods. In this article, effects of solvent-solute interaction on the manifestation of the charge induced instability in a droplet are examined. We studied the instabilities in a prototype system of a droplet comprised of charged poly(ethylene glycol) and methanol, acetonitrile, and water solvents. We observed instances of three, previously only conjectured, [S. Consta, J. Phys. Chem. B 114, 5263 (2010), 10.1021/jp912119v] mechanisms of macroion ejection. The mechanism of ejection of charged macroion in methanol is reminiscent of "pearl" model in polymer physics. In acetonitrile droplets, the instability manifests through formation of solvent spines around the solvated macroion. In water, we find that the macroion is ejected from the droplet through contiguous extrusion of a part of the chain. The difference in the morphology of the instabilities is attributed to the interplay between forces arising from the macroion solvation energy and the surface energy of the droplet interface. For the contiguous extrusion of a charged macromolecule from a droplet, we demonstrate that the proposed mechanism leads to ejection of the macromolecule from droplets with sizes well below the Rayleigh limit. The ejected macromolecule may hold charge significantly higher than that suggested by prevailing theories. The simulations reveal new mechanisms of macroion evaporation that differ from conventional charge residue model and ion evaporation mechanisms.

  5. Direct liquid-feed fuel cells: Thermodynamic and environmental concerns

    NASA Astrophysics Data System (ADS)

    Demirci, Umit B.

    The present paper briefly reviews the different direct liquid-feed fuel cells that have been regarded through the open literature. It especially focuses on thermodynamic-energetic data and toxicological-ecological hazards of the chemicals used as liquid fuels. The analysis of those two databases shows that borohydride, ethanol and 2-propanol would be the most adequate liquid fuels for the polymer electrolyte membrane fuel cell-type systems, even if they are inferior to hydrogen. All the fuels and also all the by-products stem from their decomposition are more or less harmful towards health and environment. More particularly, hydrazine should be avoided because it and its by-product are very dangerous. It is to note that the present paper does not intend to review and to compare the performances of those fuel cells because of great differences in the efforts devoted to each of them.

  6. High energy-density liquid rocket fuel performance

    NASA Technical Reports Server (NTRS)

    Rapp, Douglas C.

    1990-01-01

    A fuel performance database of liquid hydrocarbons and aluminum-hydrocarbon fuels was compiled using engine parametrics from the Space Transportation Engine Program as a baseline. Propellant performance parameters are introduced. General hydrocarbon fuel performance trends are discussed with respect to hydrogen-to-carbon ratio and heat of formation. Aluminum-hydrocarbon fuel performance is discussed with respect to aluminum metal loading. Hydrocarbon and aluminum-hydrocarbon fuel performance is presented with respect to fuel density, specific impulse, and propellant density specific impulse.

  7. Numerical study of liquid-hydrogen droplet generation from a vibrating orifice

    NASA Astrophysics Data System (ADS)

    Xu, J.; Celik, D.; Hussaini, M. Y.; Van Sciver, S. W.

    2005-08-01

    Atomic hydrogen propellant feed systems for far-future spacecraft may utilize solid-hydrogen particle carriers for atomic species that undergo recombination to create hot rocket exhaust. Such technology will require the development of particle generation techniques. One such technique could involve the production of hydrogen droplets from a vibrating orifice that would then freeze in cryogenic helium vapor. Among other quantities, the shape and size of the droplet are of particular interest. The present paper addresses this problem within the framework of the incompressible Navier-Stokes equations for multiphase flows, in order to unravel the basic mechanisms of droplet formation with a view to control them. Surface tension, one of the most important mechanisms to determine droplet shape, is modeled as the source term in the momentum equation. Droplet shape is tracked using a volume-of-fluid approach. A dynamic meshing technique is employed to accommodate the vibration of the generator orifice. Numerically predicted droplet shapes show satisfactory agreement with photographs of droplets generated in experiments. A parametric study is carried out to understand the influence of injection velocity, nozzle vibrational frequency, and amplitude on the droplet shape and size. The computational model provides a definitive qualitative picture of the evolution of droplet shape as a function of the operating parameters. It is observed that, primarily, the orifice vibrational frequency affects the shape, the vibrational amplitude affects the time until droplet detachment from the orifice, and the injection velocity affects the size. However, it does not mean that, for example, there is no secondary effect of amplitude on shape or size.

  8. Characterization of Liquid Fuel Evaporation of a Lifted Methanol Spray Flame in a Vitiated Coflow Burner

    NASA Technical Reports Server (NTRS)

    Cabra, Ricardo; Dibble, Robert W.; Chen, Jyh-Yuan

    2002-01-01

    An experimental investigation of lifted spray flames in a coflow of hot, vitiated gases is presented. The vitiated coflow burner is a spray flame that issues into a coaxial flow of hot combustion products from a lean, premixed H2/Air flame. The spray flame in a vitiated coflow emulates the combustion that occurs in many advanced combustors without the detailed fluid mechanics. Two commercially available laser diagnostic systems are used to characterize the spray flame and to demonstrate the vitiated coflow burner's amenability to optical investigation. The Ensemble Particle Concentration and Size (EPCS) system is used to measure the path-average droplet size distribution and liquid volume fraction at several axial locations while an extractive probe instrument named the Real-time Fuel-air Analyzer (RFA) is used to measure the air to fuel ratio downstream of the spray nozzle with high temporal and spatial resolution. The effect of coflow conditions (stoichiometry) and dilution of the fuel with water was studied with the EPCS optical system. As expected, results show that water retards the evaporation and combustion of fuels. Measurements obtained by the RFA extractive probe show that while the Delavan manufactured nozzle does distribute the fuel over the manufacturer specified spray angle, it unfortunately does not distribute the fuel uniformly, providing conditions that may result in the production of unwanted NOx. Despite some limitations due to the inherent nature of the experimental techniques, the two diagnostics can be readily applied to spray flames in the vitiated coflow environment.

  9. Variation of Local Liquid-Water Concentration About and Ellipsoid of Fineness Ratio 5 Moving in a Droplet Field

    NASA Technical Reports Server (NTRS)

    Dorsch, Robert G.; Brun, Rinaldo J.

    1954-01-01

    Trajectories of water droplets about an ellipsoid of revolution with a fineness ratio of 5 (which often approximates the shape of an aircraft fuselage or missile) were computed with the aid of a differential analyzer. Analyses of these trajectories indicate that the local concentration of liquid water at various points about an ellipsoid in flight through a droplet field varies considerably and under some conditions may be several times the free-stream concentration. Curves of the local concentration factor as a function of spatial position were obtained and are presented in terms of dimensionless parameters Re(sub 0) (free-stream Reynolds number) and K (inertia), which contain flight and atmospheric conditions. These curves show that the local concentration factor at any point is very sensitive to change in the dimensionless parameters Re(sub 0) and K. These data indicate that the expected local concentration factors should be considered when choosing the location of, or when determining antiicing heat requirements for, water- or ice-sensitive devices that protrude into the stream from an aircraft fuselage or missile. Similarly, the concentration factor should be considered when choosing the location on an aircraft of instruments that measure liquid-water content or droplet-size distribution in the atmosphere.

  10. The influence of design concept and liquid properties on fuel injector performance

    NASA Astrophysics Data System (ADS)

    Custer, J. R.; Rizk, N. K.

    1986-01-01

    An experimental investigation of the influence of design concept and liquid properties on fuel injector performances of airblast atomizers is carried out. Three injectors with distinctly different fuel filming concepts were employed in this program. The first nozzle is a dual-circuit atomizer with pressure swirl tip in the primary and a short prefilming secondary circuit. The second nozzle design is based on a single circuit prefilming concept. The last atomizer tested was a spray-prefilming concept in which the spray from a large pressure atomizer is directed onto an outer shroud. In the three designs the liquid sheet is exposed to high velocity airstreams on both sides once it leaves the filming surface. In the experiments designed in the present study the nozzle operating conditions, namely air/liquid ratio and nondimensional air pressure drop, and liquid properties were varied. Mean drop size and drop size distributions were measured with a laser-diffraction instrument and a photographic technique was employed for cone angle measurement. The results indicate that the method of spreading the liquid into a film has a significant effect on atomization quality. Also, for the practical range of properties of gas turbine fuels, surface tension has the most dominant effect on mean drop size for the three nozzle designs. The measurements indicate that the spray cone angle is governed by air velocity and liquid properties. The drop size distribution data followed the modified Rosin-Rammler type of distribution closely under almost all conditions. Equations to correlate mean drop sizes to the distribution parameters were derived to facilitate the prediction of the range of droplets in the spray.

  11. Nematic-field-driven positioning of particles in liquid crystal droplets.

    PubMed

    Whitmer, Jonathan K; Wang, Xiaoguang; Mondiot, Frederic; Miller, Daniel S; Abbott, Nicholas L; de Pablo, Juan J

    2013-11-27

    Common nematic oils, such as 5CB, experience planar anchoring at aqueous interfaces. When these oils are emulsified, this anchoring preference and the resulting topological constraints lead to the formation of droplets that exhibit one or two point defects within the nematic phase. Here, we explore the interactions of adsorbed particles at the aqueous interface through a combination of experiments and coarse-grained modeling, and demonstrate that surface-active particles, driven by elastic forces in the droplet, readily localize to these defect regions in a programmable manner. When droplets include two nanoparticles, these preferentially segregate to the two poles, thereby forming highly regular dipolar structures that could serve for hierarchical assembly of functional structures. Addition of sufficient concentrations of surfactant changes the interior morphology of the droplet, but pins defects to the interface, resulting in aggregation of the two particles.

  12. Nematic-Field Driven Positioning of Particles in Liquid Crystal Droplets

    PubMed Central

    Whitmer, Jonathan K.; Wang, Xiaoguang; Mondiot, Frederic; Miller, Daniel S.; Abbott, Nicholas L.; de Pablo, Juan J.

    2015-01-01

    Common nematic oils, such as 5CB, experience planar anchoring at aqueous interfaces. When these oils are emulsified, this anchoring preference and the resulting topological constraints lead to formation of droplets that exhibit one or two point defects within the nematic phase. Here, we explore the interactions of adsorbed particles at the aqueous interface through a combination of experiments and coarse-grained modeling, and demonstrate that surface-active particles, driven by elastic forces in the droplet, readily localize to these defect regions in a programmable manner. When droplets include two nanoparticles, these preferentially segregate to the two poles, thereby forming highly regular dipolar structures that could serve for hierarchical assembly of functional structures. Addition of sufficient concentrations of surfactant changes the interior morphology of the droplet, but pins defects to the interface, resulting in aggregation of the two particles. PMID:24329470

  13. Silver halide fiber-based evanescent-wave liquid droplet sensing with room temperature mid-infrared quantum cascade lasers

    NASA Astrophysics Data System (ADS)

    Chen, J. Z.; Liu, Z.; Gmachl, C. F.; Sivco, D. L.

    2005-08-01

    Quantum cascade lasers and unclad silver halide fibers were used to assemble mid-infrared fiber-optics evanescent-wave sensors suitable to measure the chemical composition of liquid droplets. The laser wavelengths were chosen to be in the regions which offer the largest absorption contrast between constituents inside the mixture droplets. A pseudo-Beer-Lambert law fits well with the experimental data. Using a 300μm diameter fiber with a 25 mm immersion length, the signal to noise ratios correspond to 1 vol.% for α-tocophenol in squalane and 2 vol.% for acetone in aqueous solution for laser wavenumbers of 1208 cm-1 and 1363 cm-1, respectively.

  14. In-situ Observation of Surface Graphitization of Gallium Droplet and Concentration of Carbon in Liquid Gallium

    NASA Astrophysics Data System (ADS)

    Ueki, Ryuichi; Nishijima, Takuya; Hikata, Takeshi; Ookubo, Soichiro; Utsunomiya, Risa; Matsuba, Teruaki; Fujita, Jun-ichi

    2012-06-01

    Although carbon has been recognized to be insoluble in gallium, we found that the outermost surface of gallium has unexpectedly high carbon solubility, particularly the limited region of about a few nanometers in depth. Our in-situ transmission electron microscope observations revealed that a graphene layer was precipitated at the surface of a gallium droplet simultaneously with gallium evaporation, and some of the droplets created an internal graphitic layer. On the basis of these experimental data, we evaluated a substantial carbon solubility that seemed to exceed about 50 at. %, but was realized in a very thin surface region of about 4 nm in depth. We believe that this high carbon solubility at the gallium surface is the key mechanism for the catalytic ability of gallium that was observed at the interface between liquid gallium and solid amorphous carbon.

  15. Atomization of liquid fuels. Part II

    NASA Technical Reports Server (NTRS)

    Kuehn, R

    1925-01-01

    This report describes the design and operation of a nozzle to inject fuel into an engine. The design of the nozzle is open, without any compulsory or automatic stop-valve. The fuel injection is regulated simply by the pressure and the adjustment of the fuel pump.

  16. High brightness EUV sources based on laser plasma at using droplet liquid metal target

    NASA Astrophysics Data System (ADS)

    Vinokhodov, A. Yu; Krivokorytov, M. S.; Sidelnikov, Yu V.; Krivtsun, V. M.; Medvedev, V. V.; Koshelev, K. N.

    2016-05-01

    We present the study of a source of extreme ultraviolet (EUV) radiation based on laser plasma generated due to the interaction of radiation from a nanosecond Nd : YAG laser with a liquidmetal droplet target consisting of a low-temperature eutectic indium–tin alloy. The generator of droplets is constructed using a commercial nozzle and operates on the principle of forced capillary jet decomposition. Long-term spatial stability of the centre-of-mass position of the droplet with the root-mean-square deviation of ~0.5 μm is demonstrated. The use of a low-temperature working substance instead of pure tin increases the reliability and lifetime of the droplet generator. For the time- and space-averaged power density of laser radiation on the droplet target 4 × 1011 W cm-2 and the diameter of radiating plasma ~80 μm, the mean efficiency of conversion of laser energy into the energy of EUV radiation at 13.5 +/- 0.135 nm equal to 2.3% (2π sr)-1 is achieved. Using the doublepulse method, we have modelled the repetitively pulsed regime of the source operation and demonstrated the possibility of its stable functioning with the repetition rate up to 8 kHz for the droplet generation repetition rate of more than 32 kHz, which will allow the source brightness to be as large as ~0.96 kW (mm2 sr)-1.

  17. High brightness EUV sources based on laser plasma at using droplet liquid metal target

    NASA Astrophysics Data System (ADS)

    Vinokhodov, A. Yu; Krivokorytov, M. S.; Sidelnikov, Yu V.; Krivtsun, V. M.; Medvedev, V. V.; Koshelev, K. N.

    2016-05-01

    We present the study of a source of extreme ultraviolet (EUV) radiation based on laser plasma generated due to the interaction of radiation from a nanosecond Nd : YAG laser with a liquidmetal droplet target consisting of a low-temperature eutectic indium-tin alloy. The generator of droplets is constructed using a commercial nozzle and operates on the principle of forced capillary jet decomposition. Long-term spatial stability of the centre-of-mass position of the droplet with the root-mean-square deviation of ~0.5 μm is demonstrated. The use of a low-temperature working substance instead of pure tin increases the reliability and lifetime of the droplet generator. For the time- and space-averaged power density of laser radiation on the droplet target 4 × 1011 W cm-2 and the diameter of radiating plasma ~80 μm, the mean efficiency of conversion of laser energy into the energy of EUV radiation at 13.5 +/- 0.135 nm equal to 2.3% (2π sr)-1 is achieved. Using the doublepulse method, we have modelled the repetitively pulsed regime of the source operation and demonstrated the possibility of its stable functioning with the repetition rate up to 8 kHz for the droplet generation repetition rate of more than 32 kHz, which will allow the source brightness to be as large as ~0.96 kW (mm2 sr)-1.

  18. Combined effects of underlying substrate and evaporative cooling on the evaporation of sessile liquid droplets.

    PubMed

    Wang, Yilin; Ma, Liran; Xu, Xuefeng; Luo, Jianbin

    2015-07-28

    The evaporation of pinned, sessile droplets resting on finite thickness substrates was investigated numerically by extending the combined field approach to include the thermal properties of the substrate. By this approach, the combined effects of the underlying substrate and the evaporative cooling were characterized. The results show that the influence of the substrate on the droplet evaporation depends largely on the strength of the evaporative cooling. When the evaporative cooling is weak, the influence of substrate is also weak. As the strength of evaporative cooling increases, the influence of the substrate becomes more and more pronounced. Further analyses indicated that it is the cooling at the droplet surface and the temperature dependence of the saturation vapor concentration that relate the droplet evaporation to the underlying substrate. This indicates that the evaporative cooling number, Ec, can be used to identify the influence of the substrate on the droplet evaporation. The theoretical predictions by the present model are compared and found to be in good agreement with the experimental measurements. The present work may contribute to the body of knowledge concerning droplet evaporation and may have applications in a wide range of industrial and scientific processes.

  19. A tunable microflow focusing device utilizing controllable moving walls and its applications for formation of micro-droplets in liquids

    NASA Astrophysics Data System (ADS)

    Lee, Chun-Hong; Hsiung, Suz-Kai; Lee, Gwo-Bin

    2007-06-01

    This study reports a new microfluidic device capable of fine-tuned sample-flow focusing and generation of micro-droplets in liquids by controlling moving wall structures. Two microfluidic components including an 'active microchannel width controller' and a 'micro chopper' can be used to fine-tune the width of the hydrodynamically pre-focused stream and subsequently generate micro-droplets. In this study, a basic concept of a 'controllable moving wall' structure was addressed and applied as the active microchannel width controller and the micro chopper to generate the proposed function. Pneumatic side chambers were placed next to a main flow channel to construct the controllable moving wall structures. The deformation of the controllable moving wall structure can be generated by the pressurized air injected into the pneumatic side chambers. The proposed chip device was fabricated utilizing polymer material such as PDMS (polydimethylsiloxane) to provide the flexibility of the controllable moving wall deformation. The microfluidic chip device with dimensions of 2.5 cm in width and 3.0 cm in length can be fabricated using a simple fabrication process. Experimental data showed that the deformation of the controllable moving wall structure can be adjusted by applying different air pressures, so that the width of the main flow channel can be controlled accordingly. By utilizing the proposed mechanism, the pre-focused dispersed phase stream could be actively focused into a narrower stream, and well-controlled micro-droplets with smaller diameters could be generated. The stream width can be reduced from 30 µm to 9 µm and micro-droplets with a diameter of 76 µm could be generated by utilizing the proposed device. In addition, to generate micro-droplets within smaller diameters, uniform size distribution of the micro-droplets can be obtained. According to the experimental results, development of the microfluidic device could be promising for a variety of applications such

  20. Development of a droplet breakup model considering aerodynamic and droplet collision effects

    NASA Technical Reports Server (NTRS)

    Wert, K. L.; Jacobs, H. R.

    1993-01-01

    A model is currently under development to predict the occurrence and outcome of spray droplet breakup induced by aerodynamic forces and droplet collisions. It is speculated that these phenomena may be significant in determining the droplet size distribution in a spray subjected to acoustic velocity fluctuations. The goal is to integrate this breakup model into a larger spray model in order to examine the effects of combustion instabilities on liquid rocket motor fuel sprays. The model is composed of three fundamental components: a dynamic equation governing the deformation of the droplet, a criterion for breakage based on the amount of deformation energy stored in the droplet and an energy balance based equation to predict the Sauter mean diameter of the fragments resulting from breakup. Comparison with published data for aerodynamic breakup indicates good agreement in terms of predicting the occurrence of breakup. However, the model significantly over predicts the size of the resulting fragments. This portion of the model is still under development.

  1. Experimental investigation of interaction processes between droplets and hot walls

    NASA Astrophysics Data System (ADS)

    Karl, A.; Frohn, A.

    2000-04-01

    A detailed experimental investigation of interaction processes of small liquid droplets with hot walls well above the Leidenfrost temperature has been carried out. The experimental method which uses monodisperse droplet streams in combination with a standard video camera allows very detailed observations and measurements with very high time resolution. The main intent of this paper is to study the mechanical behavior of liquid droplets impacting on hot walls well above the Leidenfrost temperature. A better understanding of this process may lead to a better modeling of two-phase flows, especially for applications in fuel preparation processes, combustion processes, and spray cooling. The loss of momentum of the droplets, the droplet deformation, and the onset of droplet disintegration have been investigated. For all experimental results correlations have been developed, which can be used to improve the numerical modeling of two-phase flows. Using the correlation for the loss of momentum a theoretical approximation for the maximum droplet deformation has been deduced, which yields a very good agreement with our own measurements as well as with results reported in the literature. A minimum impinging angle for droplet disintegration has been discovered for small impinging angles. Below this impinging angle no droplet disintegration is observed. This phenomenon is directly related to the energy dissipation at the wall during the interaction process. With the presented work the understanding of basic interaction processes between droplets and hot walls may be improved.

  2. Droplet-turbulence interactions in sprays exposed to supercritical environmental conditions

    NASA Technical Reports Server (NTRS)

    Santavicca, Domenic A.

    1993-01-01

    The goal of this research was to experimentally characterize the behavior of droplets in vaporizing sprays under conditions typical of those encountered in high pressure combustion systems such as liquid fueled rocket engines. Of particular interest are measurements of droplet drag and lift, droplet dispersion, droplet heating, and droplet vaporization under both subcritical and supercritical conditions. A summary of the major accomplishments achieved during the period from June 1990 through June 1993, a brief description and status report on five research areas, which were directly or indirectly supported by this grant, and a list of publications and personnel associated with this research is included.

  3. Combustion of alternate liquid fuels in high efficiency boilers

    SciTech Connect

    Murphy, E.T.

    1983-06-01

    Alternate Liquid Fuel (ALF) is a ''non-critical'' fuel oil substitute formulated by selectively blending feedstocks of recycled solvents, alcohols, mineral spirits and other combustible liquids with substandard conventional fuel oils obtained from government surplus or purchased on the spot market. Typical feedstocks are listed on Table I. These combustible liquids, reclaimed from waste streams, are generated by petro-chemical, cosmetic, pharmaceutical, electronic, environmental recovery and other industries and government (mostly military) sources. The raw waste feedstocks collected from these sources are carefully segregated, cleaned up (of suspended solids and non-combustibles) and monitored by BNL and vendors to preclude feedstocks containing halogenated hydrocarbons, PCB's, heavy metals and other toxics in excess of prescribed levels. The resulting combustible feedstocks are purchased by BNL as a boiler fuel at prices 25 to 50 percent or more below conventional fuel oil market prices. Brookhaven National Laboratory (BNL) began testing ALF on an experimental basis in 1973, in an effort to reduce the Laboratory's rapidly escalating fuel oil bills. Based on accrued experience from the tests, a 40,000 gallon per day pilot processing system was constructed in 1976. Successful operation and full scale firing of ALF prompted to BNL to build a 700,000 gallon per day processing system in 1978, and to modify the existing Central Steam Facility fuel train to accommodate a wider range of liquid fuels in 1982.

  4. Liquid-Feed Methanol Fuel Cell With Membrane Electrolyte

    NASA Technical Reports Server (NTRS)

    Surampudi, Subbarao; Narayanan, S. R.; Halpert, Gerald; Frank, Harvey; Vamos, Eugene

    1995-01-01

    Fuel cell generates electricity from direct liquid feed stream of methanol/water solution circulated in contact with anode, plus direct gaseous feed stream of air or oxygen in contact with cathode. Advantages include relative simplicity and elimination of corrosive electrolytic solutions. Offers potential for reductions in size, weight, and complexity, and for increases in safety of fuel-cell systems.

  5. Enhanced conversion of syngas to liquid motor fuels

    DOEpatents

    Coughlin, Peter K.; Rabo, Jule A.

    1986-01-01

    Synthesis gas comprising carbon monoxide and hydrogen is converted to C.sub.5.sup.+ hydrocarbons suitable for use as liquid motor fuels by contact with a dual catalyst system capable of enhancing the selectivity of said conversion to motor fuel range hydrocarbons and the quality of the resulting motor fuel product. The catalyst composition employs a Fischer-Tropsch catalyst, together with a co-catalyst/support component comprising SAPO silicoaluminophosphate, non-zeolitic molecular sieve catalyst.

  6. Enhanced catalyst for conversion of syngas to liquid motor fuels

    DOEpatents

    Coughlin, P.K.; Rabo, J.A.

    1985-12-03

    Synthesis gas comprising carbon monoxide and hydrogen is converted to C[sub 5][sup +] hydrocarbons suitable for use as liquid motor fuels by contact with a dual catalyst system capable of enhancing the selectivity of said conversion to motor fuel range hydrocarbons and the quality of the resulting motor fuel product. The catalyst composition employs a Fischer-Tropsch catalyst, together with a co-catalyst/support component comprising a SAPO silicoaluminophosphate, non-zeolitic molecular sieve catalyst.

  7. Enhanced catalyst for conversion of syngas to liquid motor fuels

    DOEpatents

    Coughlin, Peter K.; Rabo, Jule A.

    1985-01-01

    Synthesis gas comprising carbon monoxide and hydrogen is converted to C.sub.5.sup.+ hydrocarbons suitable for use as liquid motor fuels by contact with a dual catalyst system capable of enhancing the selectivity of said conversion to motor fuel range hydrocarbons and the quality of the resulting motor fuel product. The catalyst composition employs a Fischer-Tropsch catalyst, together with a co-catalyst/support component comprising SAPO silicoaluminophosphate, non-zeolitic molecular sieve catalyst.

  8. Liquid-fueled SOFC power sources for transportation

    NASA Astrophysics Data System (ADS)

    Myles, K. M.; Doshi, R.; Kumar, R.; Krumpelt, M.

    Traditionally, fuel cells have been developed for space or stationary terrestrial applications. As the first commercial 200-kW systems were being introduced by ONSI and Fuji Electric, the potentially much larger, but also more challenging, application in transportation was beginning to be addressed. As a result, fuel cell-powered buses have been designed and built, and R&D programs for fuel cell-powered passenger cars have been initiated. The engineering challenge of eventually replacing the internal combustion engine in buses, trucks, and passenger cars with fuel cell systems is to achieve much higher power densities and much lower costs than obtainable in systems designed for stationary applications. At present, the leading fuel cell candidate for transportation applications is, without question, the polymer electrolyte fuel cell (PEFC). Offering ambient temperature start-up and the potential for a relatively high power density, the polymer technology has attracted the interest of automotive manufacturers worldwide. But the difficulties of fuel handling for the PEFC have led to a growing interest in exploring the prospects for solid oxide fuel cells (SOFCs) operating on liquid fuels for transportation applications. Solid oxide fuel cells are much more compatible with liquid fuels (methanol or other hydrocarbons) and are potentially capable of power densities high enough for vehicular use. Two SOFC options for such use are discussed in this report.

  9. Liquid-fueled SOFC power sources for transportation

    SciTech Connect

    Myles, K.M.; Doshi, R.; Kumar, R.; Krumpelt, M.

    1994-11-01

    Traditionally, fuel cells have been developed for space or stationary terrestrial applications. As the first commercial 200-kW systems were being introduced by ONSI and Fuji Electric, the potentially much larger, but also more challenging, application in transportation was beginning to be addressed. As a result, fuel cell-powered buses have been designed and built, and R&D programs for fuel cell-powered passenger cars have been initiated. The engineering challenge of eventually replacing the internal combustion engine in buses, trucks, and passenger cars with fuel cell systems is to achieve much higher power densities and much lower costs than obtainable in systems designed for stationary applications. At present, the leading fuel cell candidate for transportation applications is, without question, the polymer electrolyte fuel cell (PEFC). Offering ambient temperature start-up and the potential for a relatively high power density, the polymer technology has attracted the interest of automotive manufacturers worldwide. But the difficulties of fuel handling for the PEFC have led to a growing interest in exploring the prospects for solid oxide fuel cells (SOFCs) operating on liquid fuels for transportation applications. Solid oxide fuel cells are much more compatible with liquid fuels (methanol or other hydrocarbons) and are potentially capable of power densities high enough for vehicular use. Two SOFC options for such use are discussed in this report.

  10. Active droplet generation in microfluidics.

    PubMed

    Chong, Zhuang Zhi; Tan, Say Hwa; Gañán-Calvo, Alfonso M; Tor, Shu Beng; Loh, Ngiap Hiang; Nguyen, Nam-Trung

    2016-01-01

    The reliable generation of micron-sized droplets is an important process for various applications in droplet-based microfluidics. The generated droplets work as a self-contained reaction platform in droplet-based lab-on-a-chip systems. With the maturity of this platform technology, sophisticated and delicate control of the droplet generation process is needed to address increasingly complex applications. This review presents the state of the art of active droplet generation concepts, which are categorized according to the nature of the induced energy. At the liquid/liquid interface, an energy imbalance leads to instability and droplet breakup.

  11. Active droplet generation in microfluidics.

    PubMed

    Chong, Zhuang Zhi; Tan, Say Hwa; Gañán-Calvo, Alfonso M; Tor, Shu Beng; Loh, Ngiap Hiang; Nguyen, Nam-Trung

    2016-01-01

    The reliable generation of micron-sized droplets is an important process for various applications in droplet-based microfluidics. The generated droplets work as a self-contained reaction platform in droplet-based lab-on-a-chip systems. With the maturity of this platform technology, sophisticated and delicate control of the droplet generation process is needed to address increasingly complex applications. This review presents the state of the art of active droplet generation concepts, which are categorized according to the nature of the induced energy. At the liquid/liquid interface, an energy imbalance leads to instability and droplet breakup. PMID:26555381

  12. Development of a three-dimensional correction method for optical distortion of flow field inside a liquid droplet.

    PubMed

    Gim, Yeonghyeon; Ko, Han Seo

    2016-04-15

    In this Letter, a three-dimensional (3D) optical correction method, which was verified by simulation, was developed to reconstruct droplet-based flow fields. In the simulation, a synthetic phantom was reconstructed using a simultaneous multiplicative algebraic reconstruction technique with three detectors positioned at the synthetic object (represented by the phantom), with offset angles of 30° relative to each other. Additionally, a projection matrix was developed using the ray tracing method. If the phantom is in liquid, the image of the phantom can be distorted since the light passes through a convex liquid-vapor interface. Because of the optical distortion effect, the projection matrix used to reconstruct a 3D field should be supplemented by the revision ray, instead of the original projection ray. The revision ray can be obtained from the refraction ray occurring on the surface of the liquid. As a result, the error on the reconstruction field of the phantom could be reduced using the developed optical correction method. In addition, the developed optical method was applied to a Taylor cone which was caused by the high voltage between the droplet and the substrate. PMID:27082349

  13. The Fisher Droplet Model and Physical Clusters at Liquid-Vapor Phase Coexistence with Implications for the Nuclear Phase Diagram

    NASA Astrophysics Data System (ADS)

    Lake, Peter Theodore, Jr.

    The nuclear strong force, which binds the nucleons within an atomic nucleus, is a van der Waals force. A consequence of this is that the phenomenon of liquid-vapor phase coexistence occurs in the nuclear system. The experimental means of constructing the nuclear phase diagrams rely heavily on the thermodynamics of cluster theories, theories that historically have not served in many practical applications. In this thesis I explore the validity of the ideal cluster law and the Fisher droplet model in systems where the phase diagrams are known from traditional means. For molecular fluids, I show that the phase coexistence of a wide variety of systems can be described using the Fisher theory. This study is closely related to the study of an extended principle of corresponding states. These considerations demonstrates the utility of the Fisher droplet model in describing liquid-vapor phase coexistence of van der Waals fluids. For model systems, I show that the physical clusters of the Lennard-Jones model at coexistence can be used to construct the phase diagrams of the fluid. The connection between the physical clusters and the thermodynamic properties of the vapor are established using the ideal cluster law. Furthermore, the cluster concentrations are well described by the Fisher droplet model. These considerations lead to an alternative construction of the phase diagrams for the Lennard-Jones system. The success of cluster theories to describe properties of liquid-vapor coexistence that are already well established demonstrates the validity of applying these concepts to construct the nuclear phase diagrams.

  14. Alternative Liquid Fuels Simulation Model (AltSim).

    SciTech Connect

    Baker, Arnold Barry; Williams, Ryan; Drennen, Thomas E.; Klotz, Richard

    2007-10-01

    The Alternative Liquid Fuels Simulation Model (AltSim) is a high-level dynamic simulation model which calculates and compares the production costs, carbon dioxide emissions, and energy balances of several alternative liquid transportation fuels. These fuels include: corn ethanol, cellulosic ethanol, biodiesel, and diesels derived from natural gas (gas to liquid, or GTL) and coal (coal to liquid, or CTL). AltSim allows for comprehensive sensitivity analyses on capital costs, operation and maintenance costs, renewable and fossil fuel feedstock costs, feedstock conversion efficiency, financial assumptions, tax credits, CO{sub 2} taxes, and plant capacity factor. This paper summarizes the preliminary results from the model. For the base cases, CTL and cellulosic ethanol are the least cost fuel options, at $1.60 and $1.71 per gallon, respectively. Base case assumptions do not include tax or other credits. This compares to a $2.35/gallon production cost of gasoline at September, 2007 crude oil prices ($80.57/barrel). On an energy content basis, the CTL is the low cost alternative, at $12.90/MMBtu, compared to $22.47/MMBtu for cellulosic ethanol. In terms of carbon dioxide emissions, a typical vehicle fueled with cellulosic ethanol will release 0.48 tons CO{sub 2} per year, compared to 13.23 tons per year for coal to liquid.

  15. Impact of plasma induced liquid chemistry and charge on bacteria loaded aerosol droplets

    NASA Astrophysics Data System (ADS)

    Rutherford, David; McDowell, David; Mariotti, Davide; Mahony, Charles; Diver, Declan; Potts, Hugh; Bennet, Euan; Maguire, Paul

    2014-10-01

    The introduction of living organisms, such as bacteria, into atmospheric pressure microplasmas offers a unique opportunity to study the local chemical and electrical effects on cell structure and viability. Individual bacteria, each encapsulated in an aerosol droplet, were successfully transmitted through a non-thermal equilibrium RF coaxial plasma, using a custom-design concentric double gas shroud interface and via adjustment of transit times and plasma parameters, we can control cell viability. Plasma electrical characteristics (ne ~ 1013 cm-3), droplet velocity profiles and aspects of plasma-induced droplet chemistry were determined in order to establish the nature of the bacteria in droplet environment. Plasma-exposed viable E coli cells were subsequently cultured and the growth rate curves (lag and exponential phase gradient) used to explore the effect of radical chemistry and electron bombardment on cell stress. The extent and nature of membrane disruption in viable and non-viable cells were investigated through genomic and protein/membrane lipid content estimation. We will also compare our results with simulations of the effect of bacterial presence on plasma induced droplet charging and evaporation. Funding from EPSRC acknowledged (Grants EP/K006088/1 and EP/K006142/1).

  16. Yeast Droplets

    NASA Astrophysics Data System (ADS)

    Nguyen, Baochi; Upadhyaya, Arpita; van Oudenaarden, Alexander; Brenner, Michael

    2002-11-01

    It is well known that the Young's law and surface tension govern the shape of liquid droplets on solid surfaces. Here we address through experiments and theory the shape of growing aggregates of yeast on agar substrates, and assess whether these ideas still hold. Experiments are carried out on Baker's yeast, with different levels of expressions of an adhesive protein governing cell-cell and cell-substrate adhesion. Changing either the agar concentration or the expression of this protein modifies the local contact angle of a yeast droplet. When the colony is small, the shape is a spherical cap with the contact angle obeying Young's law. However, above a critical volume this structure is unstable, and the droplet becomes nonspherical. We present a theoretical model where this instability is caused by bulk elastic effects. The model predicts that the transition depends on both volume and contact angle, in a manner quantitatively consistent with our experiments.

  17. Wettability effects on droplet coalescence

    NASA Astrophysics Data System (ADS)

    Graham, Percival; de Pauw, Dennis; Dolatabadi, Ali

    2012-11-01

    Droplet impingement has been studied since 1895, with the works of A.M. Worthington. Throughout the past century, a variety of interesting phenomena have been uncovered. These include the bouncing of droplets off of each other or liquid pools, intricate droplet splashing mechanics, and droplets bouncing off of superhydrophobic surfaces; to name a few. In addition to intricate phenomena, droplet dynamics are relevant to many engineering applications, such as painting, spray coating ink-jet printing, and ice accumulation. These fields all involve interactions between droplets; therefore, studying droplet coalescence would benefit them greatly. The works presented include the coalescence of droplets with different impact conditions, various offsets, and at different wettabilities. Surface wettabilities studied are hydrophilic, hydrophobic and superhydrophobic. Fascinating phenomena observed include, bouncing of the impinging droplet off of the sessile droplet, sliding of the impinging droplet along the sessile droplet, and induced detachment on the sessile droplet on superhydrophobic surfaces. In order to capture the maximum spreading of the merged droplets, models related to coalescence of droplets in air and maximum spreading of a single droplet are combined to yield a new model to predict the maximum spreading of head-on droplet impact. Based on the free surface, and accuracy of the analytical model, droplet impact could be viewed as a mix of droplet coalescence in a gaseous media and droplet impact on a dry surface. Funding from NSERC.

  18. Fiber-Supported Droplet Combustion Experiment on STS-94

    NASA Technical Reports Server (NTRS)

    2003-01-01

    A fuel droplet burns in the Fiber-Supported Droplet Combustion (FSDC) Experiment on STS-94, July 4 1997, MET:02/19:20 (approximate). This experiment, performed in the Middeck Glovebox, allows us to study the burning of fuels such as n-heptane, n-decane, methanol, ethanol, methanol/water mixtures, and heptane/hexadecane mixtures in droplets as large as 6 mm (nearly 1/4 inch). In this sequence, you see the burn of a 5mm droplet of n-heptane, in a 30% O2/He environment at 1 atmosphere pressure. The droplet (looking bright pink because of reflected light) hangs suspended from the supporting fiber. FSDC-2 studied fundamental phenomena related to liquid fuel droplet combustion in air. Pure fuels and mixtures of fuels were burned as isolated single and dual droplets with and without forced air convection. The FSDC guest investigator was Forman Williams, University of California, San Diego. The experiment was part of the space research investigations conducted during the Microgravity Science Laboratory-1R mission (STS-94, July 1-17 1997). Advanced combustion experiments will be a part of investigations plarned for the International Space Station.(467KB, 18-second MPEG, screen 160 x 120 pixels; downlinked video, higher quality not available) A still JPG composite of this movie is available at http://mix.msfc.nasa.gov/ABSTRACTS/MSFC-0300174.html.

  19. Liquid fuels of high octane values

    SciTech Connect

    Jessup, P.J.

    1989-03-14

    This patent describes an unleaded fuel composition having an octane rating of about 100 or more, the fuel comprising toluene and alkylate and at least two further components selected from the group consisting of methyl tertiary-butyl ether, isopentane, and n-butane. It also describes a specific composition consisting of toluene, isopentane, alkylate, and MTBE.

  20. Droplet Growth

    NASA Astrophysics Data System (ADS)

    Marder, Michael Paolo

    When a mixture of two materials, such as aluminum and tin, or alcohol and water, is cooled below a certain temperature, the two components begin to separate. If one component is dilute in the other, it may separate out in the form of small spheres, and these will begin to enlarge, depleting the supersaturated material around them. If the dynamics is sufficiently slow, thermodynamics gives one considerable information about how the droplets grow. Two types of experiment have explored this behavior and given puzzling results. Nucleation experiments measure the rate at which droplets initially appear from a seemingly homogeneous mixture. Near the critical point in binary liquids, experiments conducted in the 1960's and early 1970's showed that nucleation was vastly slower than theory seemed to predict. The resolution of this problem arises by considering in detail the dynamics of growing droplets and comparing it with what experiments actually measure. Here will be presented a more detailed comparison of theory and experiment than has before been completed, obtaining satisfactory agreement with no free parameters needed. A second type of experiment measures droplet size distributions after long times. In the late stage, droplets compete with each other for material, a few growing at the expense of others. A theory first proposed by Lifshitz and Slyozov claims that this distribution, properly scaled, should be universal, and independent of properties of materials. Yet experimental measurements consistently find distributions that are more broad and squat than the theory would predict. Satisfactory agreement with experiment can be achieved by considering two points. First, one must study the complete time development of droplet size distributions, to understand when the asymptotic regime obtains. Second, droplet size distributions are spread by correlations between droplets. If one finds a small droplet, it is small because large droplets nearby are competing with it

  1. Sealed canister liquid sampling for fuel characterization shipments

    SciTech Connect

    Trimble, D.J.

    1995-01-12

    N-Reactor spent fuel elements will be removed from the sealed fuel storage canisters in the KW Basin and shipped to the 300 Area hot cells for characterization studies. Some of the canisters contain broken fuel elements exposing metallic uranium to the canister water. The exposed uranium surfaces have reacted with the water releasing fission product nuclides to the canister water. The extent of this release is unknown, but large radionuclide inventories could cause significant releases to the basin water. To avoid this, a method is needed to evaluate the magnitude of the canister water radioactivity to help make decisions about which canisters should not be opened for fuel sampling. The objective of this document is to provide a conceptual description of the process for obtaining and evaluating gas and liquid samples from KW fuel canisters in support of fuel characterization shipments. Also described are the decisions regarding the acceptability of a sample, the actions to be taken to obtain an acceptable sample, and the logical leading to decisions about opening canisters for fuel characterization sampling. This document will help guide a safety analysis of the liquid sampling process and the development of detailed procedures for the process. Outside the scope of this document are the processes for opening canisters, selecting fuel samples from opened canisters, shipping fuel samples, and closing canisters.

  2. Multiuser Droplet Combustion Apparatus Developed to Conduct Combustion Experiments

    NASA Technical Reports Server (NTRS)

    Myhre, Craig A.

    2001-01-01

    A major portion of the energy produced in the world today comes from the combustion or burning of liquid hydrocarbon fuels in the form of droplets. However, despite vigorous scientific examinations for over a century, researchers still lack a full understanding of many fundamental combustion processes of liquid fuels. Understanding how these fuel droplets ignite, spread, and extinguish themselves will help us develop more efficient ways of energy production and propulsion, as well as help us deal better with the problems of combustion-generated pollution and fire hazards associated with liquid combustibles. The ability to conduct more controlled experiments in space, without the complication of gravity, provides scientists with an opportunity to examine these complicated processes closely. The Multiuser Droplet Combustion Apparatus (MDCA) supports this continued research under microgravity conditions. The objectives are to improve understanding of fundamental droplet phenomena affected by gravity, to use research results to advance droplet combustion science and technology on Earth, and to address issues of fire hazards associated with liquid combustibles on Earth and in space. MDCA is a multiuser facility designed to accommodate different combustion science experiments. The modular approach permits the on-orbit replacement of droplet combustion principal investigator experiments such as different fuels, droplet-dispensing needles, and droplet-tethering mechanisms. Large components such as the avionics, diagnostics, and base-plate remain on the International Space Station to reduce the launch mass of new experiments. MDCA is also designed to operate in concert with ground systems on Earth to minimize the involvement of the crew during orbit.

  3. Electrically tunable microlens arrays based on polarization-independent optical phase of nano liquid crystal droplets dispersed in polymer matrix.

    PubMed

    Yu, Ji Hoon; Chen, Hung-Shan; Chen, Po-Ju; Song, Ki Hoon; Noh, Seong Cheol; Lee, Jae Myeong; Ren, Hongwen; Lin, Yi-Hsin; Lee, Seung Hee

    2015-06-29

    Electrically tunable focusing microlens arrays based on polarization independent optical phase of nano liquid crystal droplets dispersed in polymer matrix are demonstrated. Such an optical medium is optically isotropic which is so-called an optically isotropic liquid crystals (OILC). We not only discuss the optical theory of OILC, but also demonstrate polarization independent optical phase modulation based on the OILC. The experimental results and analytical discussion show that the optical phase of OILC microlens arrays results from mainly orientational birefringence which is much larger than the electric-field-induced birefringence (or Kerr effect). The response time of OILC microlens arrays is fast~5.3ms and the tunable focal length ranges from 3.4 mm to 3.8 mm. The potential applications are light field imaging systems, 3D integrating imaging systems and devices for augment reality.

  4. Measuring cloud droplet effective radius and liquid water content using changes in degree of linear polarization along cloud depth.

    PubMed

    Kim, Dukhyeon; Lee, Jeongsoon

    2014-06-15

    Two important parameters of liquid clouds are the cloud effective size (CES) and liquid water content (LWC). To measure these parameters, we have used two multiple scattering depolarization effects: (1) the slope of the degree of linear polarization (SLDLP) at the cloud base, and (2) the saturated degree of linear polarization (SADLP) at infinite altitude. We used Monte Carlo simulation to validate this method, with the assumption that the water cloud droplet size follows a Gamma distribution. From our calculation, we find that although the SADLP varies with both extinction coefficient (or LWC) and the CES, the SLDLP varies only with the extinction coefficient. After extracting the extinction coefficient using the SLDLP, we can easily obtain the CES using the SADLP. As a result, we found that the CES and the LWC can be extracted from the experimental parameters of SLDLP and SADLP, which can be easily measured using a single wavelength depolarization LIDAR.

  5. Electrically tunable microlens arrays based on polarization-independent optical phase of nano liquid crystal droplets dispersed in polymer matrix.

    PubMed

    Yu, Ji Hoon; Chen, Hung-Shan; Chen, Po-Ju; Song, Ki Hoon; Noh, Seong Cheol; Lee, Jae Myeong; Ren, Hongwen; Lin, Yi-Hsin; Lee, Seung Hee

    2015-06-29

    Electrically tunable focusing microlens arrays based on polarization independent optical phase of nano liquid crystal droplets dispersed in polymer matrix are demonstrated. Such an optical medium is optically isotropic which is so-called an optically isotropic liquid crystals (OILC). We not only discuss the optical theory of OILC, but also demonstrate polarization independent optical phase modulation based on the OILC. The experimental results and analytical discussion show that the optical phase of OILC microlens arrays results from mainly orientational birefringence which is much larger than the electric-field-induced birefringence (or Kerr effect). The response time of OILC microlens arrays is fast~5.3ms and the tunable focal length ranges from 3.4 mm to 3.8 mm. The potential applications are light field imaging systems, 3D integrating imaging systems and devices for augment reality. PMID:26191743

  6. Self-organization in phase separation of a lyotropic liquid crystal into cellular, network and droplet morphologies.

    PubMed

    Iwashita, Yasutaka; Tanaka, Hajime

    2006-02-01

    Phase separation is one of the most fundamental physical phenomena that controls the morphology of heterogeneous structures. Phase separation of a binary mixture of simple liquids produces only two morphologies: a bicontinuous or a droplet structure in the case of a symmetric or an asymmetric composition, respectively. For complex fluids, there is a possibility to produce other interesting morphologies. We found that a network structure of the minority phase can also be induced transiently on phase separation if the dynamics of the minority phase are much slower than those of the majority phase. Here we induce a cellular structure of the minority phase intentionally with the help of its smectic ordering, using phase separation of a lyotropic liquid crystal into the isotropic and smectic phase. We can control the three morphologies, cellular, network and droplet structures, solely by changing the heating rate. We demonstrate that the kinetic interplay between phase separation and smectic ordering is a key to the morphological selection. This may provide a new route to the formation of network and cellular morphologies in soft materials.

  7. Dependence of Morphology of SiOx Nanowires on the Supersaturation of Au-Si Alloy Liquid Droplets Formed on the Au-Coated Si Substrate

    NASA Astrophysics Data System (ADS)

    Zhang, Han; Li, Ji-Xue; Jin, Ai-Zi; Zhang, Ze

    2001-11-01

    A thermodynamic theory about the dependence of morphology of SiOx nanowires on the super-saturation of alloy liquid droplets has been proposed on the basis of the vapour-liquid-solid growth mechanism and has been supported experimentally. By changing the Si concentration in the Au-Si liquid droplets formed on the Au-coated Si substrate, firework-, tulip- and bud-shaped SiOx nanowires were synthesized by a thermal evaporation method and distributed concentrically around some void defects in the Si substrate. Voids were formed underneath the surface of the Si substrate during the thermal evaporation at 850°C and resulted in the Si-concentration deficient thus different saturation of Au-Si droplets. Electron microscopy analysis showed that the nanowires had an amorphous structure and were terminated by Au-Si particles.

  8. Microgravity experiments on flame spread along fuel-droplet arrays at high temperatures

    SciTech Connect

    Mikami, Masato; Oyagi, Hiroshi; Kojima, Naoya; Wakashima, Yuichiro; Kikuchi, Masao; Yoda, Shinichi

    2006-08-15

    Microgravity experiments on droplet-array combustion were conducted under high-ambient-temperature conditions. n-Decane droplet arrays suspended on SiC fibers were inserted into a high-temperature combustion chamber and were ignited at one end to initiate the flame spread in high-temperature air. Flame-spread modes, burning behavior after the flame spread, and flame-spread rate were examined at different ambient temperatures. Experimental results showed that the appearance of flame-spread modes and the flame-spread rate were affected by the ambient temperature. The flame-spread rate increased with the ambient temperature. These facts are discussed based on the temperature effects on the droplet heating and the development of a flammable-mixture layer around the next droplet. A simple model was introduced to analyze these effects. The effects of the ambient temperature on the appearance of group combustion of the array after the flame spread and the scale effect in the flame spread are also discussed. (author)

  9. Droplet organelles?

    PubMed

    Courchaine, Edward M; Lu, Alice; Neugebauer, Karla M

    2016-08-01

    Cells contain numerous, molecularly distinct cellular compartments that are not enclosed by lipid bilayers. These compartments are implicated in a wide range of cellular activities, and they have been variously described as bodies, granules, or organelles. Recent evidence suggests that a liquid-liquid phase separation (LLPS) process may drive their formation, possibly justifying the unifying term "droplet organelle". A veritable deluge of recent publications points to the importance of low-complexity proteins and RNA in determining the physical properties of phase-separated structures. Many of the proteins linked to such structures are implicated in human diseases, such as amyotrophic lateral sclerosis (ALS). We provide an overview of the organizational principles that characterize putative "droplet organelles" in healthy and diseased cells, connecting protein biochemistry with cell physiology.

  10. Droplet organelles?

    PubMed

    Courchaine, Edward M; Lu, Alice; Neugebauer, Karla M

    2016-08-01

    Cells contain numerous, molecularly distinct cellular compartments that are not enclosed by lipid bilayers. These compartments are implicated in a wide range of cellular activities, and they have been variously described as bodies, granules, or organelles. Recent evidence suggests that a liquid-liquid phase separation (LLPS) process may drive their formation, possibly justifying the unifying term "droplet organelle". A veritable deluge of recent publications points to the importance of low-complexity proteins and RNA in determining the physical properties of phase-separated structures. Many of the proteins linked to such structures are implicated in human diseases, such as amyotrophic lateral sclerosis (ALS). We provide an overview of the organizational principles that characterize putative "droplet organelles" in healthy and diseased cells, connecting protein biochemistry with cell physiology. PMID:27357569

  11. Simulating Impacts of Disruptions to Liquid Fuels Infrastructure

    SciTech Connect

    Wilson, Michael; Corbet, Thomas F.; Baker, Arnold B.; O'Rourke, Julia M.

    2015-04-01

    This report presents a methodology for estimating the impacts of events that damage or disrupt liquid fuels infrastructure. The impact of a disruption depends on which components of the infrastructure are damaged, the time required for repairs, and the position of the disrupted components in the fuels supply network. Impacts are estimated for seven stressing events in regions of the United States, which were selected to represent a range of disruption types. For most of these events the analysis is carried out using the National Transportation Fuels Model (NTFM) to simulate the system-level liquid fuels sector response. Results are presented for each event, and a brief cross comparison of event simulation results is provided.

  12. METHOD OF LIQUID-LIQUID EXTRACTION OF BLOOD SURROGATES FOR ASSESSING HUMAN EXPOSURE TO JET FUEL

    EPA Science Inventory

    A baseline method of liquid?liquid extraction for assessing human exposure to JP-8 jet fuel was established by extracting several representative compounds ranging from very volatile to semi-volatile organic compounds, including benzene, toluene, nonane, decane, undecane, tridec...

  13. Mass spectrometric sampling of a liquid surface by nanoliter droplet generation from bursting bubbles and focused acoustic pulses: application to studies of interfacial chemistry.

    PubMed

    Thomas, Daniel A; Wang, Lingtao; Goh, Byoungsook; Kim, Eun Sok; Beauchamp, J L

    2015-03-17

    The complex chemistry occurring at the interface between liquid and vapor phases contributes significantly to the dynamics and evolution of numerous chemical systems of interest, ranging from damage to the human lung surfactant layer to the aging of atmospheric aerosols. This work presents two methodologies to eject droplets from a liquid water surface and analyze them via mass spectrometry. In bursting bubble ionization (BBI), droplet ejection is achieved via the formation of a jet following bubble rupture at the surface of a liquid to yield 250 μm diameter droplets (10 nL volume). In interfacial sampling by an acoustic transducer (ISAT), droplets are produced by focusing pulsed piezoelectric transducer-generated acoustic waves at the surface of a liquid, resulting in the ejection of droplets of 100 μm in diameter (500 pL volume). In both experimental methodologies, ejected droplets are aspirated into the inlet of the mass spectrometer, resulting in the facile formation of gas-phase ions. We demonstrate the ability of this technique to readily generate spectra of surface-active analytes, and we compare the spectra to those obtained by electrospray ionization. Charge measurements indicate that the ejected droplets are near-neutral (<0.1% of the Rayleigh limit), suggesting that gas-phase ion generation occurs in the heated transfer capillary of the instrument in a mechanism similar to thermospray or sonic spray ionization. Finally, we present the oxidation of oleic acid by ozone as an initial demonstration of the ability of ISAT-MS to monitor heterogeneous chemistry occurring at a planar water/air interface. PMID:25699657

  14. Mass spectrometric sampling of a liquid surface by nanoliter droplet generation from bursting bubbles and focused acoustic pulses: application to studies of interfacial chemistry.

    PubMed

    Thomas, Daniel A; Wang, Lingtao; Goh, Byoungsook; Kim, Eun Sok; Beauchamp, J L

    2015-03-17

    The complex chemistry occurring at the interface between liquid and vapor phases contributes significantly to the dynamics and evolution of numerous chemical systems of interest, ranging from damage to the human lung surfactant layer to the aging of atmospheric aerosols. This work presents two methodologies to eject droplets from a liquid water surface and analyze them via mass spectrometry. In bursting bubble ionization (BBI), droplet ejection is achieved via the formation of a jet following bubble rupture at the surface of a liquid to yield 250 μm diameter droplets (10 nL volume). In interfacial sampling by an acoustic transducer (ISAT), droplets are produced by focusing pulsed piezoelectric transducer-generated acoustic waves at the surface of a liquid, resulting in the ejection of droplets of 100 μm in diameter (500 pL volume). In both experimental methodologies, ejected droplets are aspirated into the inlet of the mass spectrometer, resulting in the facile formation of gas-phase ions. We demonstrate the ability of this technique to readily generate spectra of surface-active analytes, and we compare the spectra to those obtained by electrospray ionization. Charge measurements indicate that the ejected droplets are near-neutral (<0.1% of the Rayleigh limit), suggesting that gas-phase ion generation occurs in the heated transfer capillary of the instrument in a mechanism similar to thermospray or sonic spray ionization. Finally, we present the oxidation of oleic acid by ozone as an initial demonstration of the ability of ISAT-MS to monitor heterogeneous chemistry occurring at a planar water/air interface.

  15. Assessment of technology for production of liquid fuels from biomass

    SciTech Connect

    Sheppard, A.P.; Spurlock, J.M.; Birchfield, J.L.

    1981-01-01

    Technologies for liquid fuel production from biomass vary widely in states of development and extent of need for government action. Ethanol produced from grain (principally corn), for use in gasohol blends, is the most widely used and accepted biomass-based energy source in the U.S. at present. Several practical factors strongly point to needed government emphasis on research and development to advance ethanol-production technology. Liquid fuels produced from soybeans, sunflowers, Euphorbia and similar crops, or from aquatic plants, remain as longer-term potential requiring further assessment. 6 refs.

  16. The problem of liquid fuels (for aircraft engines)

    NASA Technical Reports Server (NTRS)

    Gallo, Gino

    1924-01-01

    The crisis which troubles the world market for liquid fuel in general and for carburants in particular is doubtless one of the most serious ever experienced by modern industry. It is a national crisis of economic and political independence for countries like Italy and France. The solutions suggested for meeting the lack of liquid fuel may be summed up under two general headings: the economical use of the petroleum now available; creation of petroleum substitutes from natural sources within the country. The process of cracking is described at length.

  17. The determination of water in biomass-derived liquid fuels

    SciTech Connect

    Roy, C.; De Caumia, B.

    1986-01-01

    The Dean and Stark distillation is an appropriate method for the determination of water in coal tar, bitumen and petroleum-like products. This article shows, however, that a direct application of the Dean and Stark method for the determination of water in biomass-derived liquid fuels results in incorrect estimates. Inaccuracies are due to the presence of soluble organics in the aqueous phase, which apparently form azeotropic mixtures with water and xylene and which condense and are trapped as distillate in the graduated cylinder. Instead, a Karl Fischer determination of water is recommended in the case of biomass-derived liquid fuels.

  18. An update in the 'development of alternate liquid fuels'

    NASA Astrophysics Data System (ADS)

    Rose, M. J.

    The Brookhaven National Laboratory has formulated a series of Alternate Liquid Fuels (AIF), compounded from combustible fluids such as alcohols, mineral oils and solvents, found in the waste streams of the cosmetic, petrochemical, electronics and other industries. These fuels are now being processed by a pilot plant with a productive capacity of 40,000 gallons in 8 hours, at direct costs ranging from $0.26 to $0.29 a gallon depending on selected feedstocks and blend ratios

  19. Drying grain using a hydrothermally treated liquid lignite fuel

    SciTech Connect

    Bukurov, Z.; Cvijanovic, P.; Bukurov, M.; Ljubicic, B.R.

    1995-12-01

    A shortage of domestic oil and natural gas resources in Yugoslavia, particularly for agricultural and industrial purposes, has motivated the authors to explore the possibility of using liquid lignite as an alternate fuel for drying grain. This paper presents a technical and economic assessment of the possibility of retrofitting grain-drying plants currently fueled by oil or natural gas to liquid lignite fuel. All estimates are based on lignite taken from the Kovin deposit. Proposed technology includes underwater mining techniques, aqueous ash removal, hydrothermal processing, solids concentration, pipeline transport up to 120 km, and liquid lignite direct combustion. For the characterization of Kovin lignite, standard ASTM procedures were used: proximate, ultimate, ash, heating value, and Theological analyses were performed. Results from an extensive economic analysis indicate a delivered cost of US$20/ton for the liquid lignite. For the 70 of the grain-drying plants in the province of Vojvodina, this would mean a total yearly saving of about US $2,500,000. The advantages of this concept are obvious: easy to transport and store, nonflammable, nonexplosive, nontoxic, 30%-40% cheaper than imported oil and gas, domestic fuel is at hand. The authors believe that liquid lignite, rather than an alternative, is becoming more and more an imperative.

  20. Nonlinear light scattering and spectroscopy of particles and droplets in liquids.

    PubMed

    Roke, Sylvie; Gonella, Grazia

    2012-01-01

    Nano- and microparticles have optical, structural, and chemical properties that differ from both their building blocks and the bulk materials themselves. These different physical and chemical properties are induced by the high surface-to-volume ratio. As a logical consequence, to understand the properties of nano- and microparticles, it is of fundamental importance to characterize the particle surfaces and their interactions with the surrounding medium. Recent developments of nonlinear light scattering techniques have resulted in a deeper insight of the underlying light-matter interactions. They have shed new light on the molecular mechanism of surface kinetics in solution, properties of interfacial water in contact with hydrophilic and hydrophobic particles and droplets, molecular orientation distribution of molecules at particle surfaces in solution, interfacial structure of surfactants at droplet interfaces, acid-base chemistry on particles in solution, and vesicle structure and transport properties.

  1. Oxidation Protection of Uranium Nitride Fuel using Liquid Phase Sintering

    SciTech Connect

    Dr. Paul A. Lessing

    2012-03-01

    Two methods are proposed to increase the oxidation resistance of uranium nitride (UN) nuclear fuel. These paths are: (1) Addition of USi{sub x} (e.g. U3Si2) to UN nitride powder, followed by liquid phase sintering, and (2) 'alloying' UN nitride with various compounds (followed by densification via Spark Plasma Sintering or Liquid Phase Sintering) that will greatly increase oxidation resistance. The advantages (high thermal conductivity, very high melting point, and high density) of nitride fuel have long been recognized. The sodium cooled BR-10 reactor in Russia operated for 18 years on uranium nitride fuel (UN was used as the driver fuel for two core loads). However, the potential advantages (large power up-grade, increased cycle lengths, possible high burn-ups) as a Light Water Reactor (LWR) fuel are offset by uranium nitride's extremely low oxidation resistance (UN powders oxidize in air and UN pellets decompose in hot water). Innovative research is proposed to solve this problem and thereby provide an accident tolerant LWR fuel that would resist water leaks and high temperature steam oxidation/spalling during an accident. It is proposed that we investigate two methods to increase the oxidation resistance of UN: (1) Addition of USi{sub x} (e.g. U{sub 3}Si{sub 2}) to UN nitride powder, followed by liquid phase sintering, and (2) 'alloying' UN nitride with compounds (followed by densification via Spark Plasma Sintering) that will greatly increase oxidation resistance.

  2. Precision charging of microparticles in plasma via the Rayleigh instability for evaporating charged liquid droplets

    NASA Astrophysics Data System (ADS)

    Bennet, Euan; Mahony, Charles M. O.; Potts, Hugh E.; Everest, Paul; Rutherford, David; Askari, Sadegh; Kelsey, Colin; Perez-Martin, Fatima; Hamilton, Neil; McDowell, David A.; Mariotti, Davide; Maguire, Paul; Diver, Declan A.

    2015-09-01

    In this paper we describe a novel method for delivering a precise, known amount of electric charge to a micron-sized solid target. Aerosolised microparticles passed through a plasma discharge will acquire significant electric charge. The fluid stability under evaporative stress is a key aspect that is core to the research. Initially stable charged aerosols subject to evaporation (i.e. a continually changing radius) may encounter the Rayleigh stability limit. This limit arises from the electrostatic and surface tension forces and determines the maximum charge a stable droplet can retain, as a function of radius. We demonstrate that even if the droplet charge is initially much less than the Rayleigh limit, the stability limit will be encountered as the droplet evaporates. The instability emission mechanism is strongly linked to the final charge deposited on the target, providing a mechanism that can be used to ensure a predictable charge deposit on a known encapsulated microparticle. The authors gratefully acknowledge support from EPSRC via Grant Numbers EP/K006142/1 and EP/K006088/1.

  3. Process of producing liquid hydrocarbon fuels from biomass

    DOEpatents

    Kuester, J.L.

    1987-07-07

    A continuous thermochemical indirect liquefaction process is described to convert various biomass materials into diesel-type transportation fuels which fuels are compatible with current engine designs and distribution systems comprising feeding said biomass into a circulating solid fluidized bed gasification system to produce a synthesis gas containing olefins, hydrogen and carbon monoxide and thereafter introducing the synthesis gas into a catalytic liquefaction system to convert the synthesis gas into liquid hydrocarbon fuel consisting essentially of C[sub 7]-C[sub 17] paraffinic hydrocarbons having cetane indices of 50+. 1 fig.

  4. Process of producing liquid hydrocarbon fuels from biomass

    DOEpatents

    Kuester, James L.

    1987-07-07

    A continuous thermochemical indirect liquefaction process to convert various biomass materials into diesel-type transportation fuels which fuels are compatible with current engine designs and distribution systems comprising feeding said biomass into a circulating solid fluidized bed gasification system to produce a synthesis gas containing olefins, hydrogen and carbon monoxide and thereafter introducing the synthesis gas into a catalytic liquefaction system to convert the synthesis gas into liquid hydrocarbon fuel consisting essentially of C.sub.7 -C.sub.17 paraffinic hydrocarbons having cetane indices of 50+.

  5. Droplet Core Nuclear Rocket (DCNR)

    NASA Technical Reports Server (NTRS)

    Anghaie, Samim

    1991-01-01

    The most basic design feature of the droplet core nuclear reactor is to spray liquid uranium into the core in the form of droplets on the order of five to ten microns in size, to bring the reactor to critical conditions. The liquid uranium fuel ejector is driven by hydrogen, and more hydrogen is injected from the side of the reactor to about one and a half meters from the top. High temperature hydrogen is expanded through a nozzle to produce thrust. The hydrogen pressure in the system can be somewhere between 50 and 500 atmospheres; the higher pressure is more desirable. In the lower core region, hydrogen is tangentially injected to serve two purposes: (1) to provide a swirling flow to protect the wall from impingement of hot uranium droplets: (2) to generate a vortex flow that can be used for fuel separation. The reactor is designed to maximize the energy generation in the upper region of the core. The system can result in and Isp of 2000 per second, and a thrust-to-weight ratio of 1.6 for the shielded reactor. The nuclear engine system can reduce the Mars mission duration to less than 200 days. It can reduce the hydrogen consumption by a factor of 2 to 3, which reduces the hydrogen load by about 130 to 150 metric tons.

  6. Oxides of Nitrogen Emissions from the Combustion of Monodisperse Liquid Fuel Sprays. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Sarv, H.

    1985-01-01

    A study of NO sub x formation in a one dimensional monodisperse spray combustion system, which allowed independent droplet size variation, was conducted. Temperature, NO and NO sub x concentrations were measured in the transition region, encompassing a 26 to 74 micron droplet size range. Emission measurements of hydrocarbons, carbon monoxide, carbon dioxide and oxygen were also made. The equivalence ratio was varied between 0.8 and 1.2 for the fuels used, including methanol, isopropanaol, n-heptane and n-octane. Pyridine and pyrrole were added to n-heptane as nitrogen-containing additives in order to simulate synthetic fuels. Results obtained from the postflame regions using the pure fuels indicate an optimum droplet size in the range of 43 to 58 microns for minimizing NO sub x production. For the fuels examined, the maximum NO sub x reductions relative to the small droplet size limit were about 10 to 20% for lean and 20 to 30% for stoichiometric and rich mixtures. This behavior is attributed to droplet interactions and the transition from diffusive to premixed type of burning. Preflame vaporization controls the gas phase stoichiometry which has a significant effect on the volume of the hot gases surrounding a fuel droplet, where NO sub x is formed.

  7. Cyanoborohydride-based ionic liquids as green aerospace bipropellant fuels.

    PubMed

    Zhang, Qinghua; Yin, Ping; Zhang, Jiaheng; Shreeve, Jean'ne M

    2014-06-01

    In propellant systems, the most common bipropellants are composed of two chemicals, a fuel (or reducer) and an oxidizer. Currently, the choices for propellant fuels rely mainly on hydrazine and its methylated derivatives, even though they are extremely toxic, highly volatile, sensitive to adiabatic compression (risk of detonation), and, therefore, difficult to handle. With this background, the search for alternative green propellant fuels has been an urgent goal of space science. In this study, a new family of cyanoborohydride-based ionic liquids (ILs) with properties and performances comparable to hydrazine derivatives were designed and synthesized. These new ILs as bipropellant fuels, have some unique advantages including negligible vapor pressure, ultra-short ignition delay (ID) time, and reduced synthetic and storage costs, thereby showing great application potential as environmentally friendly fuels in bipropellant formulations. PMID:24737218

  8. Cyanoborohydride-based ionic liquids as green aerospace bipropellant fuels.

    PubMed

    Zhang, Qinghua; Yin, Ping; Zhang, Jiaheng; Shreeve, Jean'ne M

    2014-06-01

    In propellant systems, the most common bipropellants are composed of two chemicals, a fuel (or reducer) and an oxidizer. Currently, the choices for propellant fuels rely mainly on hydrazine and its methylated derivatives, even though they are extremely toxic, highly volatile, sensitive to adiabatic compression (risk of detonation), and, therefore, difficult to handle. With this background, the search for alternative green propellant fuels has been an urgent goal of space science. In this study, a new family of cyanoborohydride-based ionic liquids (ILs) with properties and performances comparable to hydrazine derivatives were designed and synthesized. These new ILs as bipropellant fuels, have some unique advantages including negligible vapor pressure, ultra-short ignition delay (ID) time, and reduced synthetic and storage costs, thereby showing great application potential as environmentally friendly fuels in bipropellant formulations.

  9. Thermally induced secondary atomization of droplet in an acoustic field

    NASA Astrophysics Data System (ADS)

    Basu, Saptarshi; Saha, Abhishek; Kumar, Ranganathan

    2012-01-01

    We study the thermal effects that lead to instability and break up in acoustically levitated vaporizing fuel droplets. For selective liquids, atomization occurs at the droplet equator under external heating. Short wavelength [Kelvin-Helmholtz (KH)] instability for diesel and bio-diesel droplets triggers this secondary atomization. Vapor pressure, latent heat, and specific heat govern the vaporization rate and temperature history, which affect the surface tension gradient and gas phase density, ultimately dictating the onset of KH instability. We develop a criterion based on Weber number to define a condition for the inception of secondary atomization.

  10. HIGH ENERGY LIQUID FUELS FROM PLANTS

    SciTech Connect

    Nemethy, E. K.; Otvos, J. W.; Calvin, M.

    1980-10-01

    The heptane extract of Euphorbia lathyris has a low oxygen content and a heat valve of 42 MJ/kg which is comparable to that of crude oil (44 MJ/kg). These qualities indicate a potential for use as fuel or chemical feedstock material. Therefore we have investigated the chemical composition of this fraction in some detail. Since the amoun of the methanol fraction is quite substantial we have also identified the major components of this fraction.

  11. Liquid-fuel valve with precise throttling control

    NASA Technical Reports Server (NTRS)

    Mcdougal, A. R.; Porter, R. N.; Riebling, R. W.

    1971-01-01

    Prototype liquid-fuel valve performs on-off and throttling functions in vacuum without component cold-welding or excessive leakage. Valve design enables simple and rapid disassembly and parts replacement and operates with short working stroke, providing maximum throttling sensitivity commensurate with good control.

  12. Liquid hydrogen as a propulsion fuel, 1945-1959

    NASA Technical Reports Server (NTRS)

    Sloop, J. L.

    1978-01-01

    A historical review is presented on the research and development of liquid hydrogen for use as a propulsion fuel. The document is divided into three parts: Part 1 (1945-1950); Part 2 (1950-1957); and Part 3 (1957-1958), encompassing eleven topics. Two appendixes are included. Hydrogen Technology Through World War 2; and Propulsion Primer, Performance Parameters and Units.

  13. 40 CFR 1066.970 - Refueling test for liquid fuels.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... in § 1066.975, test vehicles for refueling emissions as described in 40 CFR 86.150-98, 86.151-98, 86.152-98, and 86.154-98. Keep records as described in 40 CFR 86.155-98. ... 40 Protection of Environment 33 2014-07-01 2014-07-01 false Refueling test for liquid fuels....

  14. 142. STANDBY PRESSURE CONTROL UNIT FOR FUEL AND LIQUID OXYGEN ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    142. STANDBY PRESSURE CONTROL UNIT FOR FUEL AND LIQUID OXYGEN IN SOUTHWEST PORTION OF CONTROL ROOM (214), LSB (BLDG. 751), FACING WEST - Vandenberg Air Force Base, Space Launch Complex 3, Launch Pad 3 East, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

  15. An impulse-driven liquid-droplet deposition interface for combining LC with MALDI MS and MS/MS.

    PubMed

    Young, J Bryce; Li, Liang

    2006-03-01

    A simple and robust impulse-driven droplet deposition system was developed for off-line liquid chromatography matrix-assisted laser desorption ionization mass spectrometry (LC-MALDI MS). The system uses a solenoid operated with a pulsed voltage power supply to generate impulses that dislodge the hanging droplets from the LC outlet directly to a MALDI plate via a momentum transfer process. There is no contact between the LC outlet and the collection surface. The system is compatible with solvents of varying polarity and viscosity, and accommodates the use of hydrophobic and hydrophilic MALDI matrices. MALDI spots are produced on-line with the separation, and do not require further processing before MS analysis. It is shown that high quality MALDI spectra from 5 fmol of pyro-Glu-fibrinopeptide deposition after LC separation could be obtained using the device, indicating that there was no sample loss in the interface. To demonstrate the analytical performance of the system as a proteome analysis tool, a range of BSA digest concentrations covering about 3 orders of magnitude, from 5 fmol to 1 pmol, were analyzed by LC-MALDI quadrupole time-of-flight MS, yielding 6 and 57% amino acid sequence coverage, respectively. In addition, a complex protein mixture of an E. coli cell extract was tryptically digested and analyzed by LC-MALDI MS, resulting in the detection of a total of 409 unique peptides from 100 fractions of 15-s intervals.

  16. Three-dimensional numerical analysis on transient Marangoni convection in a liquid droplet using spherical harmonic spectral method

    SciTech Connect

    Kuroda, Akiyoshi; Totani, Tsuyoshi; Kudo, Kazuhiko

    1999-07-01

    A method is developed to analyze the three-dimensional transient Marangoni convection in a liquid droplet heated from a concentric warm rigid sphere set in the center and cooled uniformly from its surroundings. As the field is unstable and is very sensitive to the temperature gradients along the surface, it is required for the numerical scheme to be highly accurate and be free from the effects of the polar singularities. For the purpose, a spherical harmonic spectral method is developed to analyze the flow and temperature fields in the droplet on the spherical coordinates. To check the validity of the newly developed numerical method, two calculations were carried out with two initial conditions; a warm spot was set initially around a point on the equatorial line in one case, and around the north point in the other case. These initial conditions are physically similar to each other but treated mathematically or numerically in different manner on the spherical coordinates. If an inadequate numerical scheme is used, the calculated results in these two cases may become physically different from each other. The transient behaviors of the velocity and the temperature fields calculated by the present method are observed carefully. And it is found that the results of the two cases show a good agreement with each other. It indicates that the present method is free from the effects of the direction of the coordinates.

  17. Evaporation and ignition of droplets in combustion chambers modeling and simulation

    NASA Astrophysics Data System (ADS)

    Betelin, V. B.; Smirnov, N. N.; Nikitin, V. F.; Dushin, V. R.; Kushnirenko, A. G.; Nerchenko, V. A.

    2012-01-01

    Computer simulation of liquid fuel jet injection into heated atmosphere of combustion chamber, mixture formation, ignition and combustion need adequate modeling of evaporation, which is extremely important for the curved surfaces in the presence of strong heat and mass diffusion fluxes. Combustion of most widely spread hydrocarbon fuels takes place in a gas-phase regime. Thus, evaporation of fuel from the surface of droplets turns to be one of the limiting factors of the process as well. The problems of fuel droplets atomization, evaporation being the key factors for heterogeneous reacting mixtures, the non-equilibrium effects in droplets atomization and phase transitions will be taken into account in describing thermal and mechanical interaction of droplets with streaming flows. In the present paper processes of non-equilibrium evaporation of small droplets will be discussed. As it was shown before, accounting for non-equilibrium effects in evaporation for many types of widely used liquids is crucial for droplet diameters less than 100 μm, while the surface tension effects essentially manifest only for droplets below 0.1 μm. Investigating the behavior of individual droplets in a heated air flow allowed to distinguish two scenarios for droplet heating and evaporation. Small droplets undergo successively heating, then cooling due to heat losses for evaporation, and then rapid heating till the end of their lifetime. Larger droplets could directly be heated up to a critical temperature and then evaporate rapidly. Droplet atomization interferes the heating, evaporation and combustion scenario. The scenario of fuel spray injection and self-ignition in a heated air inside combustion chamber has three characteristic stages. At first stage of jet injection droplets evaporate very rapidly thus cooling the gas at injection point, the liquid jet is very short and changes for a vapor jet. At second stage liquid jet is becoming longer, because evaporation rate decreases due

  18. A fresh look at coal-derived liquid fuels

    SciTech Connect

    Paul, A.D.

    2009-01-15

    35% of the world's energy comes from oil, and 96% of that oil is used for transportation. The current number of vehicles globally is estimated to be 700 million; that number is expected to double overall by 2030, and to triple in developing countries. Now consider that the US has 27% of the world's supply of coal yet only 2% of the oil. Coal-to-liquids technologies could bridge the gap between US fuel supply and demand. The advantages of coal-derived liquid fuels are discussed in this article compared to the challenges of alternative feedstocks of oil sands, oil shale and renewable sources. It is argued that pollutant emissions from coal-to-liquid facilities could be minimal because sulfur compounds will be removed, contaminants need to be removed for the FT process, and technologies are available for removing solid wastes and nitrogen oxides. If CO{sub 2} emissions for coal-derived liquid plants are captured and sequestered, overall emissions of CO{sub 2} would be equal or less than those from petroleum. Although coal liquefaction requires large volumes of water, most water used can be recycled. Converting coal to liquid fuels could, at least in the near term, bring a higher level of stability to world oil prices and the global economy and could serve as insurance for the US against price hikes from oil-producing countries. 7 figs.

  19. Electrolyte creepage barrier for liquid electrolyte fuel cells

    DOEpatents

    Li, Jian; Farooque, Mohammad; Yuh, Chao-Yi

    2008-01-22

    A dielectric assembly for electrically insulating a manifold or other component from a liquid electrolyte fuel cell stack wherein the dielectric assembly includes a substantially impermeable dielectric member over which electrolyte is able to flow and a barrier adjacent the dielectric member and having a porosity of less than 50% and greater than 10% so that the barrier is able to measurably absorb and chemically react with the liquid electrolyte flowing on the dielectric member to form solid products which are stable in the liquid electrolyte. In this way, the barrier inhibits flow or creepage of electrolyte from the dielectric member to the manifold or component to be electrically insulated from the fuel cell stack by the dielectric assembly.

  20. Atomization of liquid fuels. Part I

    NASA Technical Reports Server (NTRS)

    Kuehn,

    1925-01-01

    In the present treatise we will consider chiefly the problem of solid injection in comparison with air injection. On leaving the valve or nozzle through one or more small openings, the fuel is split up into innumerable fine drops, which penetrate the combustion chamber in divergent directions in the form of a conical jet. The efficiency of this jet is judged from the following three viewpoints: 1) with respect to the fineness of atomization; 2) with respect to the direction or distribution of sprayed particles; 3) with respect to the penetration of the particles.

  1. Determination of Flow Rates in Capillary Liquid Chromatography Coupled to a Nanoelectrospray Source using Droplet Image Analysis Software.

    PubMed

    Cohen, Alejandro M; Soto, Axel J; Fawcett, James P

    2016-08-01

    Liquid chromatography coupled to electrospray tandem mass spectrometry (LC-ESI-MS/MS) is widely used in proteomic and metabolomic workflows. Considerable analytical improvements have been observed when the components of LC systems are scaled down. Currently, nano-ESI is typically done at capillary LC flow rates ranging from 200 to 300 nL/min. At these flow rates, trouble shooting and leak detection of LC systems has become increasingly challenging. In this paper we present a novel proof-of-concept approach to measure flow rates at the tip of electrospray emitters when the ionization voltage is turned off. This was achieved by estimating the changes in the droplet volume over time using digital image analysis. The results are comparable with the traditional methods of measuring flow rates, with the potential advantages of being fully automatable and nondisruptive. PMID:27351615

  2. Surfactant-Induced Ordering and Wetting Transitions of Droplets of Thermotropic Liquid Crystals “Caged” Inside Partially Filled Polymeric Capsules

    PubMed Central

    2015-01-01

    We report a study of the wetting and ordering of thermotropic liquid crystal (LC) droplets that are trapped (or “caged”) within micrometer-sized cationic polymeric microcapsules dispersed in aqueous solutions of surfactants. When they were initially dispersed in water, we observed caged, nearly spherical droplets of E7, a nematic LC mixture, to occupy ∼40% of the interior volume of the polymeric capsules [diameter of 6.7 ± 0.3 μm, formed via covalent layer-by-layer assembly of branched polyethylenimine and poly(2-vinyl-4,4-dimethylazlactone)] and to contact the interior surface of the capsule wall at an angle of ∼157 ± 11°. The internal ordering of LC within the droplets corresponded to the so-called bipolar configuration (distorted by contact with the capsule walls). While the effects of dodecyltrimethylammonium bromide (DTAB) and sodium dodecyl sulfate (SDS) on the internal ordering of “free” LC droplets are similar, we observed the two surfactants to trigger strikingly different wetting and configurational transitions when LC droplets were caged within polymeric capsules. Specifically, upon addition of SDS to the aqueous phase, we observed the contact angles (θ) of caged LC on the interior surface of the capsule to decrease, resulting in a progression of complex droplet shapes, including lenses (θ ≈ 130 ± 10°), hemispheres (θ ≈ 89 ± 5°), and concave hemispheres (θ < 85°). The wetting transitions induced by SDS also resulted in changes in the internal ordering of the LC to yield states topologically equivalent to axial and radial configurations. Although topologically equivalent to free droplets, the contributions that surface anchoring, LC elasticity, and topological defects make to the free energy of caged LC droplets differ from those of free droplets. Overall, these results and others reported herein lead us to conclude that caged LC droplets offer a platform for new designs of LC-droplet-based responsive soft matter that cannot

  3. 40 CFR 270.235 - Options for incinerators, cement kilns, lightweight aggregate kilns, solid fuel boilers, liquid...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ..., lightweight aggregate kilns, solid fuel boilers, liquid fuel boilers and hydrochloric acid production furnaces... Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES (CONTINUED) EPA..., solid fuel boilers, liquid fuel boilers and hydrochloric acid production furnaces to minimize...

  4. Atomized spraying of liquid metal droplets on desired substrate surfaces as a generalized way for ubiquitous printed electronics

    NASA Astrophysics Data System (ADS)

    Zhang, Qin; Gao, Yunxia; Liu, Jing

    2014-09-01

    A direct electronics printing technique through atomized spraying for patterning room-temperature liquid metal droplets on desired substrate surfaces is proposed and experimentally demonstrated for the first time. This method is highly flexible and capable of fabricating electronic components on various target objects, with either flat or rough surfaces, made of different materials, or having different orientations from 2D to 3D geometrical configurations. With a pre-designed mask, the liquid metal ink can be directly deposited on the substrate to form various specific patterns which lead to the rapid prototyping of electronic devices. Further, extended printing strategies were also suggested to illustrate the adaptability of the method. For example, it can be used for making transparent conductive film with an optical transmittance of 47 % and a sheet resistance of 5.167Ω/□ due to natural porous structure. Different from the former direct writing technology where large surface tension and poor adhesion between the liquid metal and the substrate often impede the flexible printing process, the liquid metal here no longer needs to be pre-oxidized to guarantee its applicability on target substrates. One critical mechanism was that the atomized liquid metal microdroplets can be quickly oxidized in the air due to its large specific surface area, resulting in a significant increase of the adhesion capacity and thus firm deposition of the ink to the substrate. This study paved a generalized way for pervasively and directly printing electronics on various substrates which are expected to be significant in a wide spectrum of electrical engineering areas.

  5. Two Droplets Burning Side by Side

    NASA Technical Reports Server (NTRS)

    2003-01-01

    The Fiber-Supported Droplet Combustion (FSDC) experiment team got more than twice as many burns have been completed as were originally scheduled for STS-95. This image was taken July 12, 1997, MET:10/08:13 (approximate). As shown here, scientists were able to burn two droplets side by side, more closely mimicking behavior of burning fuel in an engine. This shows ignition of a single drop that subsequently burned while a fan blew through the chamber, giving the scientists data on burning with convection, but no buoyancy -- an important distinction when you're trying to solve a problem by breaking it into parts. FSDC-2 studied fundamental phenomena related to liquid fuel droplet combustion in air. Pure fuels and mixtures of fuels were burned as isolated single and dual droplets with and without forced air convection. The FSDC guest investigator was Forman Williams, University of California, San Diego. The experiment was part of the space research investigations conducted during the Microgravity Science Laboratory-1R mission (STS-94, July 1-17 1997). Advanced combustion experiments will be a part of investigations plarned for the International Space Station. (1.1 MB, 11-second MPEG, screen 320 x 240 pixels; downlinked video, higher quality not available) A still JPG composite of this movie is available at http://mix.msfc.nasa.gov/ABSTRACTS/MSFC-0300176.html.

  6. Silver halide fiber-based evanescent-wave liquid droplet sensing with thermoelectrically cooled room temperature mid-infrared quantum cascade lasers

    NASA Astrophysics Data System (ADS)

    Chen, Jian Z.; Liu, Zhijun; Gmachl, Claire F.; Sivco, Deborah L.

    2005-11-01

    Quantum cascade lasers coupled directly to unclad silver halide fibers were used to assemble mid-infrared fiber-optics evanescent-wave sensors suitable to measure the chemical composition of simple liquid droplets. Quantum cascade lasers can be designed to emit across a wide range of mid-infrared wavelengths by tailoring the quantum-well structure, and the wavelength can be fine tuned by a thermoelectric cooler. Here, laser wavelengths were chosen which offer the largest absorption contrast between two constituents of a droplet. The laser was coupled to an unclad silver halide fiber, which penetrates through the droplet resting on a hydrophobic surface. For the same liquid composition and droplet size, the transmitted intensity is weaker for a droplet on a 1H,1H,2H,2H-perfluoro-octyltrichlorosilane coated glass slide than for one on a hexadecanethiol (HDT) coated Au-covered glass slide because of the high reflectivity of the HDT/Au surface at mid-infrared wavelengths. The absorption coefficients of water, glycerol, α-tocophenol acetate, and squalane were measured by varying the immersion length of the fiber; i.e. the droplet size. A pseudo-Beer-Lambert law fits well with the experimental data. We tested both aqueous liquid mixtures (acetone/water and ethanol/water) and oil-base solutions (n-dodecane/squalane and α-tocophenol acetate/squalane); α-tocophenol acetate and squalane are common ingredients of cosmetics, either as active ingredients or for chemical stabilization. Using a 300μm diameter silver halide fiber with a 25mm immersion length, the detection limits are 1 vol.% for α-tocophenol in squalane and 2 vol.% for acetone in water for laser wavenumbers of 1208 cm -1 and 1363 cm -1, respectively. This work was previously been reported in J. Z. Chen et al. Optics Express 13, 5953 (2005).

  7. 40 CFR 270.235 - Options for incinerators, cement kilns, lightweight aggregate kilns, solid fuel boilers, liquid...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ..., lightweight aggregate kilns, solid fuel boilers, liquid fuel boilers and hydrochloric acid production furnaces..., solid fuel boilers, liquid fuel boilers and hydrochloric acid production furnaces to minimize emissions... incinerator, cement kiln, lightweight aggregate kiln, solid fuel boiler, liquid fuel boiler, or...

  8. 40 CFR 270.235 - Options for incinerators, cement kilns, lightweight aggregate kilns, solid fuel boilers, liquid...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ..., lightweight aggregate kilns, solid fuel boilers, liquid fuel boilers and hydrochloric acid production furnaces..., solid fuel boilers, liquid fuel boilers and hydrochloric acid production furnaces to minimize emissions... incinerator, cement kiln, lightweight aggregate kiln, solid fuel boiler, liquid fuel boiler, or...

  9. 40 CFR 270.235 - Options for incinerators, cement kilns, lightweight aggregate kilns, solid fuel boilers, liquid...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ..., lightweight aggregate kilns, solid fuel boilers, liquid fuel boilers and hydrochloric acid production furnaces..., solid fuel boilers, liquid fuel boilers and hydrochloric acid production furnaces to minimize emissions... incinerator, cement kiln, lightweight aggregate kiln, solid fuel boiler, liquid fuel boiler, or...

  10. 40 CFR 270.235 - Options for incinerators, cement kilns, lightweight aggregate kilns, solid fuel boilers, liquid...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ..., lightweight aggregate kilns, solid fuel boilers, liquid fuel boilers and hydrochloric acid production furnaces..., solid fuel boilers, liquid fuel boilers and hydrochloric acid production furnaces to minimize emissions... incinerator, cement kiln, lightweight aggregate kiln, solid fuel boiler, liquid fuel boiler, or...

  11. Enzymantic Conversion of Coal to Liquid Fuels

    SciTech Connect

    Richard Troiano

    2011-01-31

    The work in this project focused on the conversion of bituminous coal to liquid hydrocarbons. The major steps in this process include mechanical pretreatment, chemical pretreatment, and finally solubilization and conversion of coal to liquid hydrocarbons. Two different types of mechanical pretreatment were considered for the process: hammer mill grinding and jet mill grinding. After research and experimentation, it was decided to use jet mill grinding, which allows for coal to be ground down to particle sizes of 5 {mu}m or less. A Fluid Energy Model 0101 JET-O-MIZER-630 size reduction mill was purchased for this purpose. This machine was completed and final testing was performed on the machine at the Fluid Energy facilities in Telford, PA. The test results from the machine show that it can indeed perform to the required specifications and is able to grind coal down to a mean particle size that is ideal for experimentation. Solubilization and conversion experiments were performed on various pretreated coal samples using 3 different approaches: (1) enzymatic - using extracellular Laccase and Manganese Peroxidase (MnP), (2) chemical - using Ammonium Tartrate and Manganese Peroxidase, and (3) enzymatic - using the live organisms Phanerochaete chrysosporium. Spectral analysis was used to determine how effective each of these methods were in decomposing bituminous coal. After analysis of the results and other considerations, such as cost and environmental impacts, it was determined that the enzymatic approaches, as opposed to the chemical approaches using chelators, were more effective in decomposing coal. The results from the laccase/MnP experiments and Phanerochaete chrysosporium experiments are presented and compared in this final report. Spectra from both enzymatic methods show absorption peaks in the 240nm to 300nm region. These peaks correspond to aromatic intermediates formed when breaking down the coal structure. The peaks then decrease in absorbance over time

  12. Recent Advances In Science Support For Isolated Droplet Combustion Experiments

    NASA Technical Reports Server (NTRS)

    Dryer, F. L.; Kazakov, A.; Urban, B. D.; Kroenlein, K.

    2003-01-01

    In a joint program involving Prof. F.A. Williams of the University of California, San Diego and Dr. V. Nayagam of the National Center for Microgravity Research, the combustion characteristics of isolated liquid fuel droplets of n-heptane, n-decane, methanol, methanol-water, ethanol and ethanol-water having initial diameters between about 1 mm and 6 mm continues to be investigated. The objectives of the work are to improve fundamental knowledge of droplet combustion dynamics for pure fuels and fuel-water mixtures through microgravity experiments and theoretical analyses. The Princeton contributions support the engineering design, data analysis, and data interpretation requirements for the study of initially single component, spherically symmetric, isolated droplet combustion studies through experiments and numerical modeling. UCSD contributions are described in a companion communication in this conference. The Princeton effort also addresses the analyses of Fiber Supported Droplet Combustion (FSDC) experiments conducted with the above fuels and collaborative work with others who are investigating droplet combustion in the presence of steady convection. A thorough interpretation of droplet burning behavior for n-heptane and n-decane over a relatively wide range of conditions also involves the influences of sooting on the combustion behavior, and this particular aspect on isolated burning of droplets is under consideration in a collaborative program underway with Drexel University. This collaboration is addressed in another communication at this conference. The one-dimensional, time-dependent, numerical modeling approach that we have continued to evolve for analyzing isolated, quiescent droplet combustion data has been further applied to investigate several facets of isolated droplet burning of simple alcohols, n-heptane, and n-decane. Some of the new results are described below.

  13. Dispersive liquid-liquid microextraction based on solidification of floating organic droplet for the determination of triazine and triazoles in mineral water samples.

    PubMed

    Bolzan, Cátia M; Caldas, Sergiane S; Guimarães, Bruno S; Primel, Ednei G

    2016-09-01

    A simple, rapid, and sensitive method for the determination of atrazine, simazine, cyproconazole, tebuconazole, and epoxiconazole in mineral water employing the dispersive liquid-liquid microextraction with solidification of a floating organic drop with determination by liquid chromatography tandem mass spectrometry has been developed. A mixed solution of 250 μL 1-dodecanol and 1250 μL methanol was injected rapidly into 10 mL aqueous solution (pH 7.0) with 2% w/v NaCl. After centrifugation for 5 min at 2000 rpm, the organic solvent droplets floated on the surface of the aqueous solution and the floating solvent solidified. The method limits of detection were between 3.75 and 37.5 ng/L and limits of quantification were between 12.5 and 125 ng/L. The recoveries ranged from 70 to 118% for repeatability and between 76 and 95% for intermediate precision with a relative standard deviation from 2 to 18% for all compounds. Low matrix effect was observed. The proposed method can be successfully applied in routine analysis for determination of pesticide residues in mineral water samples, allowing for monitoring of triazine and triazoles at levels below the regulatory limits set by international and national legislations. PMID:27391582

  14. Dispersive liquid-liquid microextraction based on solidification of floating organic droplet for the determination of triazine and triazoles in mineral water samples.

    PubMed

    Bolzan, Cátia M; Caldas, Sergiane S; Guimarães, Bruno S; Primel, Ednei G

    2016-09-01

    A simple, rapid, and sensitive method for the determination of atrazine, simazine, cyproconazole, tebuconazole, and epoxiconazole in mineral water employing the dispersive liquid-liquid microextraction with solidification of a floating organic drop with determination by liquid chromatography tandem mass spectrometry has been developed. A mixed solution of 250 μL 1-dodecanol and 1250 μL methanol was injected rapidly into 10 mL aqueous solution (pH 7.0) with 2% w/v NaCl. After centrifugation for 5 min at 2000 rpm, the organic solvent droplets floated on the surface of the aqueous solution and the floating solvent solidified. The method limits of detection were between 3.75 and 37.5 ng/L and limits of quantification were between 12.5 and 125 ng/L. The recoveries ranged from 70 to 118% for repeatability and between 76 and 95% for intermediate precision with a relative standard deviation from 2 to 18% for all compounds. Low matrix effect was observed. The proposed method can be successfully applied in routine analysis for determination of pesticide residues in mineral water samples, allowing for monitoring of triazine and triazoles at levels below the regulatory limits set by international and national legislations.

  15. Hydrogen engines based on liquid fuels, a review

    NASA Technical Reports Server (NTRS)

    Houseman, J.; Voecks, G. E.

    1981-01-01

    The concept of storing hydrogen as part of a liquid fuel, such as gasoline or methanol, and subsequent onboard generation of the hydrogen from such liquids, is reviewed. Hydrogen generation processes, such as steam reforming, partial oxidation, and thermal decomposition are evaluated in terms of theoretical potential and practical limitations, and a summary is presented on the major experimental work on conversion of gasoline and methanol. Results of experiments indicate that onboard hydrogen generation from methanol is technically feasible and will yield substantial improvements in fuel economy and emissions, especially if methanol decomposition is brought about by the use of engine exhaust heat; e.g., a methanol decomposition reactor of 3.8 provides hydrogen-rich gas for a 4 cylinder engine (1.952), and 80% of the methanol is converted, engine exhaust gas being the only heat supply. A preliminary outline of the development of a methanol-based hydrogen engine and a straight hydrogen engine is presented.

  16. Catalyst for converting synthesis gas to liquid motor fuels

    DOEpatents

    Coughlin, Peter K.

    1986-01-01

    The addition of an inert metal component, such as gold, silver or copper, to a Fischer-Tropsch catalyst comprising cobalt enables said catalyst to convert synthesis gas to liquid motor fuels at about 240.degree.-370.degree. C. with advantageously reduced selectivity of said cobalt for methane in said conversion. The catalyst composition can advantageously include a support component, such as a molecular sieve, co-catalyst/support component or a combination of such support components.

  17. Vacuum plasma spray applications on liquid fuel rocket engines

    NASA Astrophysics Data System (ADS)

    McKechnie, T. N.; Zimmerman, F. R.; Bryant, M. A.

    1992-07-01

    The vacuum plasma spray process (VPS) has been developed by NASA and Rocketdyne for a variety of applications on liquid fuel rocket engines, including the Space Shuttle Main Engine. These applications encompass thermal barrier coatings which are thermal shock resistant for turbopump blades and nozzles; bond coatings for cryogenic titanium components; wear resistant coatings and materials; high conductivity copper, NaRloy-Z, combustion chamber liners, and structural nickel base material, Inconel 718, for nozzle and combustion chamber support jackets.

  18. Enhanced catalyst for converting synthesis gas to liquid motor fuels

    DOEpatents

    Coughlin, Peter K.

    1986-01-01

    The conversion of synthesis gas to liquid molar fuels by means of a cobalt Fischer-Tropsch catalyst composition is enhanced by the addition of molybdenum, tungsten or a combination thereof as an additional component of said composition. The presence of the additive component increases the olefinic content of the hydrocarbon products produced. The catalyst composition can advantageously include a support component, such as a molecular sieve, co-catalyst/support component or a combination of such support components.

  19. Sensitive detection of trypsin using liquid-crystal droplet patterns modulated by interactions between poly-L-lysine and a phospholipid monolayer.

    PubMed

    Zhang, Minmin; Jang, Chang-Hyun

    2014-08-25

    Liquid-crystal (LC) droplet patterns are formed on a glass slide by evaporating a solution of nematic LC dissolved in heptane. In the presence of an anionic phospholipid, 1,2-dioleoyl-sn-glycero-3-phospho-rac-(1-glycerol) (DOPG), the LCs display a dark cross pattern, indicating a homeotropic orientation. When LC patterns are incubated with an aqueous mixture of DOPG and poly-L-lysine (PLL), there is a transition in the LC pattern from a dark cross to a bright fan shape due to the electrostatic interaction between DOPG and PLL. Known to catalyze the hydrolysis of PLL into oligopeptide fragments, trypsin is preincubated with PLL, significantly decreasing the interactions between PLL and DOPG. LCs adopt a perpendicular orientation at the water-LC droplet interface, which gives rise to a dark cross pattern. This optical response of LC droplets is the basis for a quick and sensitive biosensor for trypsin. PMID:24850496

  20. Droplet impact on a thin liquid film: anatomy of the splash

    NASA Astrophysics Data System (ADS)

    Josserand, Christophe; Ray, Pascal; Zaleski, Stéphane

    2016-09-01

    We investigate the dynamics of drop impact on a thin liquid film at short times in order to identify the mechanisms of splashing formation. Using numerical simulations and scaling analysis, we show that the splashing formation depends both on the inertial dynamics of the liquid and the cushioning of the gas. Two asymptotic regimes are identified, characterized by a new dimensionless number $J$: when the gas cushioning is weak, the jet is formed after a sequence of bubbles are entrapped and the jet speed is mostly selected by the Reynolds number of the impact. On the other hand, when the air cushioning is important, the lubrication of the gas beneath the drop and the liquid film controls the dynamics, leading to a single bubble entrapment and a weaker jet velocity.

  1. Droplets Generated from a new OGEE shaped, liquid, air-shear, electrostatic nozzle

    NASA Technical Reports Server (NTRS)

    Inculet, I. I.; Base, T. E.; Castle, G. S. P.

    1982-01-01

    A series of experimental tests was carried out on an 'OGEE' shaped planform, liquid air-shear electrostatic nozzle. Liquid was ejected from the upper surface of the nozzle and was then dispersed and atomized efficiently by a high speed air flow passing over the nozzle and by the effect of two very strong coherent air vortices generated by the 'OGEE' shaped nozzle surface. Initial test results which are presented show the nozzle to perform far superior to a similar delta wing shaped design which is used extensively in various industries applications.

  2. Transient behaviour of deposition of liquid metal droplets on a solid substrate

    NASA Astrophysics Data System (ADS)

    Chapuis, J.; Romero, E.; Soulié, F.; Bordreuil, C.; Fras, G.

    2016-10-01

    This paper investigates the mechanisms that contribute to the spreading of liquid metal macro-drop deposited during Stationary Pulsed Gas Metal Arc Welding on an initially cold solid workpiece. Surface tension and inertial effects take an important part in the behaviour of the liquid metal macro-drop, but in this configuration the influence of energetic effects can also be significant. The experimental results are discussed in the light of dimensional analysis in order to appreciate the influence of the process parameters and the physical mechanisms involved on the spreading of a macro-drop. A law is established to model forced non-isothermal spreading.

  3. NREL Research on Converting Biomass to Liquid Fuels

    ScienceCinema

    None

    2016-07-12

    Unlike other renewable energy sources, biomass can be converted directly into liquid fuels, called "biofuels," to help meet transportation fuel needs. The two most common types of biofuels are ethanol and biodiesel. Today, ethanol is made from starches and sugars, but at the National Renewable Energy Laboratory (NREL) scientists are developing technology to allow it to be made from cellulose and hemicellulose, the fibrous material that makes up the bulk of most plant matter. Biodiesel is made by combining alcohol (usually methanol) with vegetable oil, animal fat, or recycled cooking grease. It can be used as an additive (typically 20%) to reduce vehicle emissions or in its pure form as a renewable alternative fuel for diesel engines. For a text version of this video visit http://www.nrel.gov/learning/re_biofuels.html

  4. NREL Research on Converting Biomass to Liquid Fuels

    SciTech Connect

    2010-01-01

    Unlike other renewable energy sources, biomass can be converted directly into liquid fuels, called "biofuels," to help meet transportation fuel needs. The two most common types of biofuels are ethanol and biodiesel. Today, ethanol is made from starches and sugars, but at the National Renewable Energy Laboratory (NREL) scientists are developing technology to allow it to be made from cellulose and hemicellulose, the fibrous material that makes up the bulk of most plant matter. Biodiesel is made by combining alcohol (usually methanol) with vegetable oil, animal fat, or recycled cooking grease. It can be used as an additive (typically 20%) to reduce vehicle emissions or in its pure form as a renewable alternative fuel for diesel engines. For a text version of this video visit http://www.nrel.gov/learning/re_biofuels.html

  5. Reactive Leidenfrost droplets

    NASA Astrophysics Data System (ADS)

    Raufaste, C.; Bouret, Y.; Celestini, F.

    2016-05-01

    We experimentally investigate the reactivity of Leidenfrost droplets with their supporting substrates. Several organic liquids are put into contact with a copper substrate heated above their Leidenfrost temperature. As the liquid evaporates, the gaseous flow cleans the superficial copper oxide formed at the substrate surface and the reaction maintains a native copper spot below the evaporating droplet. The copper spot can reach several times the droplet size for the most reactive organic compounds. This study shows an interesting coupling between the physics of the Leidenfrost effect and the mechanics of reactive flows. Different applications are proposed such as drop motion tracking and vapor flow monitoring.

  6. Producing liquid fuels from coal: prospects and policy issues

    SciTech Connect

    James T. Bartis; Frank Camm; David S. Ortiz

    2008-07-01

    The increase in world oil prices since 2003 has prompted renewed interest in producing and using liquid fuels from unconventional resources, such as biomass, oil shale, and coal. This book focuses on issues and options associated with establishing a commercial coal-to-liquids (CTL) industry within the United States. It describes the technical status, costs, and performance of methods that are available for producing liquids from coal; the key energy and environmental policy issues associated with CTL development; the impediments to early commercial experience; and the efficacy of alternative federal incentives in promoting early commercial experience. Because coal is not the only near-term option for meeting liquid-fuel needs, this book also briefly reviews the benefits and limitations of other approaches, including the development of oil shale resources, the further development of biomass resources, and increasing dependence on imported petroleum. A companion document provides a detailed description of incentive packages that the federal government could offer to encourage private-sector investors to pursue early CTL production experience while reducing the probability of bad outcomes and limiting the costs that might be required to motivate those investors. (See Rand Technical Report TR586, Camm, Bartis, and Bushman, 2008.) 114 refs., 2 figs., 16 tabs., 3 apps.

  7. Ionic Liquids and New Proton Exchange Membranes for Fuel Cells

    NASA Technical Reports Server (NTRS)

    Belieres, Jean-Philippe

    2004-01-01

    There is currently a great surge of activity in fuel cell research as laboratories across the world seek to take advantage of the high energy capacity provided by &el cells relative to those of other portable electrochemical power systems. Much of this activity is aimed at high temperature fie1 cells, and a vital component of such &el cells must be the availability of a high temperature stable proton-permeable membrane. NASA Glenn Research Center is greatly involved in developing this technology. Other approaches to the high temperature fuel cell involve the use of single- component or almost-single-component electrolytes that provide a path for protons through the cell. A heavily researched case is the phosphoric acid fuel cell, in which the electrolyte is almost pure phosphoric acid and the cathode reaction produces water directly. The phosphoric acid fie1 cell delivers an open circuit voltage of 0.9 V falling to about 0.7 V under operating conditions at 170 C. The proton transport mechanism is mainly vehicular in character according to the viscosity/conductance relation. Here we describe some Proton Transfer Ionic Liquids (PTILs) with low vapor pressure and high temperature stability that have conductivities of unprecedented magnitude for non-aqueous systems. The first requirement of an ionic liquid is that, contrary to experience with most liquids consisting of ions, it must have a melting point that is not much above room temperature. The limit commonly suggested is 100 C. PTILs constitute an interesting class of non-corrosive proton-exchange electrolyte, which can serve well in high temperature (T = 100 - 250 C) fuel cell applications. We will present cell performance data showing that the open circuit voltage output, and the performance of a simple H2(g)Pt/PTIL/Pt/O2(g) fuel cell may be superior to those of the equivalent phosphoric acid electrolyte fuel cell both at ambient temperature and temperatures up to and above 200 C. My work at NASA Glenn Research

  8. Liquid fuel molten salt reactors for thorium utilization

    DOE PAGESBeta

    Gehin, Jess C.; Powers, Jeffrey J.

    2016-04-08

    Molten salt reactors (MSRs) represent a class of reactors that use liquid salt, usually fluoride- or chloride-based, as either a coolant with a solid fuel (such as fluoride salt-cooled high temperature reactors) or as a combined coolant and fuel with fuel dissolved in a carrier salt. For liquid-fuelled MSRs, the salt can be processed online or in a batch mode to allow for removal of fission products as well as introduction of fissile fuel and fertile materials during reactor operation. The MSR is most commonly associated with the 233U/thorium fuel cycle, as the nuclear properties of 233U combined with themore » online removal of parasitic absorbers allow for the ability to design a thermal-spectrum breeder reactor; however, MSR concepts have been developed using all neutron energy spectra (thermal, intermediate, fast, and mixed-spectrum zoned concepts) and with a variety of fuels including uranium, thorium, plutonium, and minor actinides. Early MSR work was supported by a significant research and development (R&D) program that resulted in two experimental systems operating at ORNL in the 1960s, the Aircraft Reactor Experiment and the Molten Salt Reactor Experiment. Subsequent design studies in the 1970s focusing on thermal-spectrum thorium-fueled systems established reference concepts for two major design variants: (1) a molten salt breeder reactor (MSBR), with multiple configurations that could breed additional fissile material or maintain self-sustaining operation; and (2) a denatured molten salt reactor (DMSR) with enhanced proliferation-resistance. T MSRs has been selected as one of six most promising Generation IV systems and development activities have been seen in fast-spectrum MSRs, waste-burning MSRs, MSRs fueled with low-enriched uranium (LEU), as well as more traditional thorium fuel cycle-based MSRs. This study provides an historical background of MSR R&D efforts, surveys and summarizes many of the recent development, and provides analysis comparing

  9. Gas-to-liquids synthetic fuels for use in fuel cells : reformability, energy density, and infrastructure compatibility.

    SciTech Connect

    Ahmed, S.; Kopasz, J. P.; Russell, B. J.; Tomlinson, H. L.

    1999-09-08

    The fuel cell has many potential applications, from power sources for electric hybrid vehicles to small power plants for commercial buildings. The choice of fuel will be critical to the pace of its commercialization. This paper reviews the various liquid fuels being considered as an alternative to direct hydrogen gas for the fuel cell application, presents calculations of the hydrogen and carbon dioxide yields from autothermal reforming of candidate liquid fuels, and reports the product gas composition measured from the autothermal reforming of a synthetic fuel in a micro-reactor. The hydrogen yield for a synthetic paraffin fuel produced by a cobalt-based Fischer-Tropsch process was found to be similar to that of retail gasoline. The advantages of the synthetic fuel are that it contains no contaminants that would poison the fuel cell catalyst, is relatively benign to the environment, and could be transported in the existing fuel distribution system.

  10. Investigation on cone jetting regimes of liquid droplets subjected to pyroelectric fields induced by laser blasts

    NASA Astrophysics Data System (ADS)

    Gennari, Oriella; Battista, Luigi; Silva, Benjamin; Grilli, Simonetta; Miccio, Lisa; Vespini, Veronica; Coppola, Sara; Orlando, Pierangelo; Aprin, Laurent; Slangen, Pierre; Ferraro, Pietro

    2015-02-01

    Electrical conductivity and viscosity play a major role in the tip jetting behaviour of liquids subjected to electrohydrodynamic (EHD) forces, thus influencing significantly the printing performance. Recently, we developed a nozzle- and electrode-free pyro-EHD system as a versatile alternative to conventional EHD configurations and we demonstrated different applications, including inkjet printing and three-dimensional lithography. However, only dielectric fluids have been used in all of those applications. Here, we present an experimental characterization of the pyro-EHD jetting regimes, induced by laser blasts, of sessile drops in case of dielectric and conductive liquids in order to extend the applicability of the system to a wider variety of fields including biochemistry and biotechnology where conductive aqueous solutions are typically used.

  11. A Microfluidic Platform for the Rapid Determination of Distribution Coefficients by Gravity-Assisted Droplet-Based Liquid-Liquid Extraction.

    PubMed

    Poulsen, Carl Esben; Wootton, Robert C R; Wolff, Anders; deMello, Andrew J; Elvira, Katherine S

    2015-06-16

    The determination of pharmacokinetic properties of drugs, such as the distribution coefficient (D) is a crucial measurement in pharmaceutical research. Surprisingly, the conventional (gold standard) technique used for D measurements, the shake-flask method, is antiquated and unsuitable for the testing of valuable and scarce drug candidates. Herein, we present a simple microfluidic platform for the determination of distribution coefficients using droplet-based liquid-liquid extraction. For simplicity, this platform makes use of gravity to enable phase separation for analysis and is 48 times faster and uses 99% less reagents than performing an equivalent measurement using the shake-flask method. Furthermore, the D measurements achieved in our platform are in good agreement with literature values measured using traditional shake-flask techniques. Since D is affected by volume ratios, we use the apparent acid dissociation constant, pK', as a proxy for intersystem comparison. Our platform determines a pK' value of 7.24 ± 0.15, compared to 7.25 ± 0.58 for the shake-flask method in our hands and 7.21 for the shake-flask method in the literature. Devices are fabricated using injection molding, the batchwise fabrication time is <2 min per device (at a cost of $1 U.S. per device), and the interdevice reproducibility is high.

  12. A Microfluidic Platform for the Rapid Determination of Distribution Coefficients by Gravity-Assisted Droplet-Based Liquid-Liquid Extraction.

    PubMed

    Poulsen, Carl Esben; Wootton, Robert C R; Wolff, Anders; deMello, Andrew J; Elvira, Katherine S

    2015-06-16

    The determination of pharmacokinetic properties of drugs, such as the distribution coefficient (D) is a crucial measurement in pharmaceutical research. Surprisingly, the conventional (gold standard) technique used for D measurements, the shake-flask method, is antiquated and unsuitable for the testing of valuable and scarce drug candidates. Herein, we present a simple microfluidic platform for the determination of distribution coefficients using droplet-based liquid-liquid extraction. For simplicity, this platform makes use of gravity to enable phase separation for analysis and is 48 times faster and uses 99% less reagents than performing an equivalent measurement using the shake-flask method. Furthermore, the D measurements achieved in our platform are in good agreement with literature values measured using traditional shake-flask techniques. Since D is affected by volume ratios, we use the apparent acid dissociation constant, pK', as a proxy for intersystem comparison. Our platform determines a pK' value of 7.24 ± 0.15, compared to 7.25 ± 0.58 for the shake-flask method in our hands and 7.21 for the shake-flask method in the literature. Devices are fabricated using injection molding, the batchwise fabrication time is <2 min per device (at a cost of $1 U.S. per device), and the interdevice reproducibility is high. PMID:25984969

  13. Fragment structure from vapor explosions during the impact of molten metal droplets into a liquid pool

    NASA Astrophysics Data System (ADS)

    Kouraytem, Nadia; Li, Er Qiang; Vakarelski, Ivan Uriev; Thoroddsen, Sigurdur

    2015-11-01

    High-speed video imaging is used in order to look at the impact of a molten metal drop falling into a liquid pool. The interaction regimes are three: film boiling, nucleate boiling or vapor explosion. Following the vapor explosion, the metal fragments and different textures are observed. It was seen that, using a tin alloy, a porous structure results whereas using a distinctive eutectic metal, Field's metal, micro beads are formed. Different parameters such as the metal type, molten metal temperature, pool surface tension and pool boiling temperature have been altered in order to assess the role they play on the explosion dynamics and the molten metal's by product.

  14. Effect of an oxygen plasma on the physical and chemical properties of several fluids for the liquid droplet radiator

    NASA Technical Reports Server (NTRS)

    Gulino, D. A.; Coles, C. E.

    1986-01-01

    The Liquid Droplet Radiator is one of several radiator systems currently under investigation by NASA Lewis Research Center. It involves the direct exposure of the radiator working fluid to the space environment. An area of concern is the potential harmful effects of the low-Earth-orbit atomic oxygen environment on the radiator working fluid. To address this issue, seven candidate fluids were exposed to an oxygen plasma environment in a laboratory plasma asher. The fluids studied included Dow Corning 705 Diffusion Pump Fluid, polymethylphenylsiloxane and polydimethlsiloxane, both of which are experimental fluids made by Dow Corning, Fomblin Z25, made by Montedison, and three fluids from the Krytox family of fluids, Krytox 143AB, 1502, and 16256, which are made by DuPont. The fluids were characterized by noting changes in visual appearance, physical state, mass, and infrared spectra. Of the fluids tested, the Fomblin and the three Krytoxes were the least affected by the oxygen plasma. The only effect noted was a change in mass, which was most likely due to an oxygen-catalyzed deploymerization of the fluid molecule.

  15. Effect of an oxygen plasma on the physical and chemical properties of several fluids for the Liquid Droplet Radiator

    NASA Technical Reports Server (NTRS)

    Gulino, Daniel A.; Coles, Carolyn E.

    1987-01-01

    The Liquid Droplet Radiator is one of several radiator systems currently under investigation by NASA Lewis Research Center. It involves the direct exposure of the radiator working fluid to the space environment. An area of concern is the potential harmful effects of the low-Earth-orbit atomic oxygen environment on the radiator working fluid. To address this issue, seven candidate fluids were exposed to an oxygen plasma environment in a laboratory plasma asher. The fluids studied included Dow Corning 705 Diffusion Pump Fluid, polymethylphenylsiloxane and polydimethylsiloxane, both of which are experimental fluids made by Dow Corning, Fomblin Z25, made by Montedison, and three fluids from the Krytox family of fluids, Krytox 143AB, 1502, and 16256, which are made by DuPont. The fluids were characterized by noting changes in visual appearance, physical state, mass, and infrared spectra. Of the fluids tested, the Fomblin and the three Krytoxes were the least affected by the oxygen plasma. The only effect noted was a change in mass, which was most likely due to an oxygen-catalyzed depolymerization of the fluid molecule.

  16. Preliminary Investigation of Performance and Starting Characteristics of Liquid Fluorine : Liquid Oxygen Mixtures with Jet Fuel

    NASA Technical Reports Server (NTRS)

    Rothenberg, Edward A; Ordin, Paul M

    1954-01-01

    The performance of jet fuel with an oxidant mixture containing 70 percent liquid fluorine and 30 percent liquid oxygen by weight was investigated in a 500-pound-thrust engine operating at a chamber pressure of 300 pounds per square inch absolute. A one-oxidant-on-one-fuel skewed-hole impinging-jet injector was evaluated in a chamber of characteristic length equal to 50 inches. A maximum experimental specific impulse of 268 pound-seconds per pound was obtained at 25 percent fuel, which corresponds to 96 percent of the maximum theoretical specific impulse based on frozen composition expansion. The maximum characteristic velocity obtained was 6050 feet per second at 23 percent fuel, or 94 percent of the theoretical maximum. The average thrust coefficient was 1.38 for the 500-pound thrust combustion-chamber nozzle used, which was 99 percent of the theoretical (frozen) maximum. Mixtures of fluorine and oxygen were found to be self-igniting with jet fuel with fluorine concentrations as low as 4 percent, when low starting propellant flow rated were used.

  17. Water droplets also swim!

    NASA Astrophysics Data System (ADS)

    van der Linden, Marjolein; Izri, Ziane; Michelin, Sébastien; Dauchot, Olivier

    2015-03-01

    Recently there has been a surge of interest in producing artificial swimmers. One possible path is to produce self-propelling droplets in a liquid phase. The self-propulsion often relies on complex mechanisms at the droplet interface, involving chemical reactions and the adsorption-desorption kinetics of the surfactant. Here, we report the spontaneous swimming of droplets in a very simple system: water droplets immersed in an oil-surfactant medium. The swimmers consist of pure water, with no additional chemical species inside: water droplets also swim! The swimming is very robust: the droplets are able to transport cargo such as large colloids, salt crystals, and even cells. In this talk we discuss the origin of the spontaneous motion. Water from the droplet is solubilized by the reverse micellar solution, creating a concentration gradient of swollen reverse micelles around each droplet. By generalizing a recently proposed instability mechanism, we explain how spontaneous motion emerges in this system at sufficiently large Péclet number. Our water droplets in an oil-surfactant medium constitute the first experimental realization of spontaneous motion of isotropic particles driven by this instability mechanism.

  18. The effect of turbulence on the stability of liquid jets and the resulting droplet size distributions. Third quarterly technical report, July 1, 1993--September 30, 1993

    SciTech Connect

    Mansour, A.; Chigier, N.

    1993-12-01

    Laminar and turbulent columns of liquids issuing from capillary tubes were studied in order to determine the effects of turbulence on the stability of liquid jets and to establish the influence of liquid turbulence on droplet size distributions after breakup. Two capillary tubes were chosen with diameters D{sub 1}=3.0mm and D{sub 2}=1.2mm; jet Reynolds numbers were 1000--30000, and 400--7200. For water injection into stagnant air, stability curve is bounded by a laminar portion, where a jet radius and {delta}{sub o} initial disturbance amplitude, and a fully developed turbulent portion characterized by high initial disturbance amplitude (ln(a/{delta}{sub o,T}) {approximately} 4.85). In the transition region, ln(a/{delta}{sub o}) is not single valued; it decreases with increasing Reynolds number. In absence of aerodynamic effects, turbulent jets are as stable as laminar jets. For this breakup mode turbulence propagates initial disturbances with amplitudes orders of magnitude larger than laminar jets ({delta}{sub o,T}=28{times}10{sup 6} {delta}{sub o,L}). Growth rates of initial disturbances are same for both laminar and turbulent columns with theoretical Weber values. Droplet size distribution is bi-modal; the number ratio of large (> D/2), to small (< D/2) droplets is 3 and independent of Reynolds number. For laminar flow optimum wavelength ({lambda}{sub opt}) corresponding to fastest growing disturbance is equal to 4.45D, exactly the theoretical Weber value. For turbulent flow conditions, the turbulent column segments. Typically, segments with lengths of one to several wavelengths, detach from the liquid jet. The long ligaments contract under the action of surface tension, resulting in droplet sizes larger than predicted by Rayleigh and Weber. For turbulent flow conditions, {lambda}{sub opt} = 9.2D, about 2 times the optimum Weber wavelength.

  19. Correlation between the liquid fuel properties: Density, viscosity and surface tension and the drop sizes produced by an SI engine pintle-type port fuel injector

    SciTech Connect

    Williams, P.; Beckwith, P.

    1994-10-01

    Droplet size measurements were performed on the spray from a pintle-type gasoline injector. These quantified the influence of the fuel properties, relative fuel/air velocity and manifold air density upon the droplet sizes. Dimensional analysis and knowledge of the atomization process were used to derive equations predicting mean droplet diameters. Constants and exponents used in these equations were evaluated by correlation with the measured data. The equations were used to predict the individual or combined influence of the above variables. It is concluded that the influence of variations in properties between production gasolines on atomization is likely to be small. 13 refs., 13 figs., 10 tabs.

  20. Vaporization of droplets in premixing chambers

    NASA Technical Reports Server (NTRS)

    Yule, A. J.; Chigier, N. A.

    1980-01-01

    Detailed measurements were made of the structures of turbulent fuel sprays vaporizing in heated airstreams. The measurements show the size dependent vaporization and dispersion of the droplets and the important influence of the large eddies in the turbulence. The measurements form a data base for the development of models of fuel spray vaporization. Two laser techniques were specially developed for the investigation. A laser tomography technique converts line-of-sight light scattering measurements into time averaged 'point' measurements of droplet size distribution and volume concentration. A laser anemometer particle sizing technique was further developed to permit accurate measurements of individual particle sizes and velocities, with backscatter collection of light. The experiments are combined with heat transfer models to analyze the performance of miniature thermocouples in liquid sprays.

  1. Combustion Of Moving Droplets And Of Droplets Suspended Within A Convective Environment: Transient Numerical Results

    NASA Technical Reports Server (NTRS)

    Gogos, George; Pope, Daniel N.

    2003-01-01

    The problem considered is that of a single-component liquid fuel (n-heptane) droplet undergoing evaporation and combustion in a hot, convective, low pressure, zero-gravity environment of infinite expanse. For a moving droplet, the relative velocity (U(sub infinity)) between the droplet and freestream is subject to change due to the influence of the drag force on the droplet. For a suspended droplet, the relative velocity is kept constant. The governing equations for the gas-phase and the liquid-phase consist of the unsteady, axisymmetric equations of mass, momentum, species (gas-phase only) and energy conservation. Interfacial conservation equations are employed to couple the two phases. Variable properties are used in the gas- and liquid-phase. Multicomponent diffusion in the gas-phase is accounted for by solving the Stefan-Maxwell equations for the species diffusion velocities. A one-step overall reaction is used to model the combustion. The governing equations are discretized using the finite volume and SIMPLEC methods. A colocated grid is adopted. Hyperbolic tangent stretching functions are used to concentrate grid points near the fore and aft lines of symmetry and at the droplet surface in both the gas- and liquid-phase. The discretization equations are solved using the ADI method with the TDMA used on each line of the two alternating directions. Iterations are performed within each time-step until convergence is achieved. The grid spacing, size of the computational domain and time-step were tested to ensure that all solutions are independent of these parameters. A detailed discussion of the numerical model is given.

  2. Catalysts for conversion of syngas to liquid motor fuels

    DOEpatents

    Rabo, Jule A.; Coughlin, Peter K.

    1987-01-01

    Synthesis gas comprising carbon monoxide and hydrogen is converted to C.sub.5.sup.+ hydrocarbons suitable for use as liquid motor fuels by contact with a dual catalyst composition capable of ensuring the production of only relatively minor amounts of heavy products boiling beyond the diesel oil range. The catalyst composition, having desirable stability during continuous production operation, employs a Fischer-Tropsch catalyst, together with a co-catalyst/support component. The latter component is a steam-stabilized zeolite Y catalyst of hydrophobic character, desirably in acid-extracted form.

  3. Direct conversion of light hydrocarbon gases to liquid fuel

    SciTech Connect

    Foral, M.J.

    1990-01-01

    The objective of this program is to investigate the direct conversion of light gaseous hydrocarbons, such as those produced during Fischer-Tropsch synthesis or as a product of gasification, to liquid transportation fuels via a partial oxidation process. The process will be tested in an existing pilot plant to obtain credible mass balances. Specific objectives to be met include determination of optimal process conditions, investigation of various processing options (e.g. feed injection, product quench, and recycle systems), and evaluation of the various options will be performed as experimental data become available.

  4. Visualization of Gas-to-Liquid (GTL) Fuel Liquid Length and Soot Formation in the Constant Volume Combustion Chamber

    NASA Astrophysics Data System (ADS)

    Azimov, Ulugbek; Kim, Ki-Seong

    In this research, GTL spray combustion was visualized in an optically accessible quiescent constant-volume combustion chamber. The results were compared with the spray combustion of diesel fuel. Fast-speed photography with direct laser sheet illumination was used to determine the fuel liquid-phase length, and shadowgraph photography was used to determine the distribution of the sooting area in the fuel jet. The results showed that the fuel liquid-phase length of GTL fuel jets stabilized at about 20-22mm from the injector orifice and mainly depended on the ambient gas temperature and fuel volatility. GTL had a slightly shorter liquid length than that of the diesel fuel. This tendency was also maintained when multiple injection strategy was applied. The penetration of the tip of the liquid-phase fuel during pilot injection was a little shorter than the penetration during main injection. The liquid lengths during single and main injections were identical. In the case of soot formation, the results showed that soot formation was mainly affected by air-fuel mixing, and had very weak dependence on fuel volatility.

  5. Single Droplet Combustion of Decane in Microgravity: Experiments and Numerical Modeling

    NASA Technical Reports Server (NTRS)

    Dietrich, D. L.; Struk, P. M.; Ikegam, M.; Xu, G.

    2004-01-01

    This paper presents experimental data on single droplet combustion of decane in microgravity and compares the results to a numerical model. The primary independent experiment variables are the ambient pressure and oxygen mole fraction, pressure, droplet size (over a relatively small range) and ignition energy. The droplet history (D(sup 2) history) is non-linear with the burning rate constant increasing throughout the test. The average burning rate constant, consistent with classical theory, increased with increasing ambient oxygen mole fraction and was nearly independent of pressure, initial droplet size and ignition energy. The flame typically increased in size initially, and then decreased in size, in response to the shrinking droplet. The flame standoff increased linearly for the majority of the droplet lifetime. The flame surrounding the droplet extinguished at a finite droplet size at lower ambient pressures and an oxygen mole fraction of 0.15. The extinction droplet size increased with decreasing pressure. The model is transient and assumes spherical symmetry, constant thermo-physical properties (specific heat, thermal conductivity and species Lewis number) and single step chemistry. The model includes gas-phase radiative loss and a spherically symmetric, transient liquid phase. The model accurately predicts the droplet and flame histories of the experiments. Good agreement requires that the ignition in the experiment be reasonably approximated in the model and that the model accurately predict the pre-ignition vaporization of the droplet. The model does not accurately predict the dependence of extinction droplet diameter on pressure, a result of the simplified chemistry in the model. The transient flame behavior suggests the potential importance of fuel vapor accumulation. The model results, however, show that the fractional mass consumption rate of fuel in the flame relative to fuel vaporized is close to 1.0 for all but the lowest ambient oxygen mole

  6. Ionic liquid-assisted liquid-phase microextraction based on the solidification of floating organic droplets combined with high performance liquid chromatography for the determination of benzoylurea insecticide in fruit juice.

    PubMed

    Yang, Miyi; Zhang, Panjie; Hu, Lu; Lu, Runhua; Zhou, Wenfeng; Zhang, Sanbing; Gao, Haixiang

    2014-09-19

    A green, simple, and efficient method, ionic liquid-assisted liquid-liquid microextraction based on the solidification of floating organic droplets (ILSFOD-LLME) collected via a bell-shaped collection device (BSCD) coupled to high performance liquid chromatography with a variable-wavelength detector, was developed for the preconcentration and analysis of seven benzoylurea insecticides (BUs) in fruit juice. In the proposed method, the low-density solvent 1-dodecanol and the ionic liquid trihexyl(tetradecyl)phosphonium hexafluorophosphate ([P14, 6, 6, 6]PF6) were used as extractant. The extraction solvent droplet was easily collected and separated by the BSCD without centrifugation. The experimental parameters were optimized by the one-factor-at-a-time approach and were followed using an orthogonal array design. The results indicated the different effects of each parameter for extraction efficiency. Under the optimal conditions in the water model, the limits of detection for the analytes varied from 0.03 to 0.28μgL(-1). The enrichment factors ranged from 160 to 246. Linearities were achieved for hexaflumuron and flufenoxuron in the range of 0.5-500μgL(-1), for triflumuron, lufenuron and diafenthiuron in the range of 1-500μgL(-1), and for diflubenzuron and chlorfluazuron in the range of 5-500μgL(-1); the correlation coefficients for the BUs ranged from 0.9960 to 0.9990 with recoveries of 75.6-113.9%. Finally, the developed technique was successfully applied to real fruit juice with acceptable results. The relative standard deviations (RSDs) of the seven BUs at two spiked levels (50 and 200μgL(-1)) varied between 0.1% and 7.3%. PMID:25124227

  7. Ionic liquid-assisted liquid-phase microextraction based on the solidification of floating organic droplets combined with high performance liquid chromatography for the determination of benzoylurea insecticide in fruit juice.

    PubMed

    Yang, Miyi; Zhang, Panjie; Hu, Lu; Lu, Runhua; Zhou, Wenfeng; Zhang, Sanbing; Gao, Haixiang

    2014-09-19

    A green, simple, and efficient method, ionic liquid-assisted liquid-liquid microextraction based on the solidification of floating organic droplets (ILSFOD-LLME) collected via a bell-shaped collection device (BSCD) coupled to high performance liquid chromatography with a variable-wavelength detector, was developed for the preconcentration and analysis of seven benzoylurea insecticides (BUs) in fruit juice. In the proposed method, the low-density solvent 1-dodecanol and the ionic liquid trihexyl(tetradecyl)phosphonium hexafluorophosphate ([P14, 6, 6, 6]PF6) were used as extractant. The extraction solvent droplet was easily collected and separated by the BSCD without centrifugation. The experimental parameters were optimized by the one-factor-at-a-time approach and were followed using an orthogonal array design. The results indicated the different effects of each parameter for extraction efficiency. Under the optimal conditions in the water model, the limits of detection for the analytes varied from 0.03 to 0.28μgL(-1). The enrichment factors ranged from 160 to 246. Linearities were achieved for hexaflumuron and flufenoxuron in the range of 0.5-500μgL(-1), for triflumuron, lufenuron and diafenthiuron in the range of 1-500μgL(-1), and for diflubenzuron and chlorfluazuron in the range of 5-500μgL(-1); the correlation coefficients for the BUs ranged from 0.9960 to 0.9990 with recoveries of 75.6-113.9%. Finally, the developed technique was successfully applied to real fruit juice with acceptable results. The relative standard deviations (RSDs) of the seven BUs at two spiked levels (50 and 200μgL(-1)) varied between 0.1% and 7.3%.

  8. Direct liquid-feed fuel cell with membrane electrolyte and manufacturing thereof

    NASA Technical Reports Server (NTRS)

    Narayanan, Sekharipuram (Inventor); Surampudi, Subbarao (Inventor); Halpert, Gerald (Inventor)

    1999-01-01

    An improved direct liquid-feed fuel cell having a solid membrane electrolyte for electrochemical reactions of an organic fuel. Improvements in interfacing of the catalyst layer and the membrane and activating catalyst materials are disclosed.

  9. Study of Hydrogen Recovery Systems for Gas Vented While Refueling Liquid-Hydrogen Fueled Aircraft

    NASA Technical Reports Server (NTRS)

    Baker, C. R.

    1979-01-01

    Methods of capturing and reliquefying the cold hydrogen vapor produced during the fueling of aircraft designed to utilize liquid hydrogen fuel were investigated. An assessment of the most practical, economic, and energy efficient of the hydrogen recovery methods is provided.

  10. Estimation of Droplet Size and Liquid Water Content Using Radar and Lidar: Marine Cumulus Clouds

    NASA Astrophysics Data System (ADS)

    Vivekanandan, J. Vivek; Jensen, Jorgen; Ellis, Scott; Morley, Bruce; Tsai, Peisang; Spuler, Scott; Ghate, Virendra; Schwartz, Christian

    2016-04-01

    During the Cloud Systems Evolution in the Trades (CSET) field campaign airborne measurements from the High-Performance Instrumented Airborne Platform for Environmental Research (HIAPER) Cloud Radar (HCR) and the High Spectral Resolution Lidar (HSRL) were made in the North Pacific. In addition, in situ observations of cloud and aerosols size distributions and radiation were also collected. The HCR operated at a frequency of 94 GHz (3 mm wavelength) and collected observations at high temporal (0.5 sec) and range (30 m) resolution. The capability of HCR is enhanced by the coordination with the HSRL that made high temporal and range resolution observations of calibrated backscatter and extinction. The lidar, designed and built by the University of Wisconsin. The radar and lidar are designed to fly on the NCAR Gulfstream V HIAPER aircraft. The remote and in situ measurements collected during CSET offer opportunities for evaluating the engineering performance of the instruments and developing cloud microphysical scientific products. The coincident HCR and HSRL measurements are analyzed for assess their utility to characterize cloud boundaries, estimate liquid water content (LWC) and mean particle size. Retrievals of LWC and mean particle sizes from remote radar and lidar measurements will be compared with those from the in situ instruments.

  11. Symbiotic Nuclear—Coal Systems for Production of Liquid Fuels

    NASA Astrophysics Data System (ADS)

    Taczanowski, S.

    The notion of safety is not confined to the technological or non-proliferation aspects. It covers also the elements of energy policy: irrational reactions of societies, emotions, egoistic interests of more or less powerful pressure of economical and external political factors. One should be conscious that the country's privilege of being equipped by the Nature with rich resources of oil or gas is not solely economical, but even more a political one. Simultaneously, the gradual depletion of world hydrocarbons that draws behind irrevocable price increase has to be expected within the time scale of exploitation of power plants (now amounted to ~60 years). Therefore consequences of energy policy last much longer than the perspectives the political or economical decision makers are planning and acting within and the public is expecting successes and finally evaluating them. The world oil and gas resources are geopolitically very non-uniformly distributed, in contrast to coal and uranium. Since the level of energy self-sufficiency of the EU is highest for coal, the old idea of synfuels production from coal is recalled. Yet, in view of limits to the CO2 emissions in the EU another method has to be used here than the conventional coal liquefaction just applied in China. Simultaneously, an interesting evolution of energy prices was be observed, namely an increase in that of motor fuels in contrast to that of electricity remaining well stable. This fact suggests that the use of electricity (mainly the off-peak load), generated without emissions of CO2 for production of liquid fuels can prove reasonable. Thus, the essence of the presented idea of coal-nuclear symbiosis lies in the supply of energy in the form of H2, necessary for this process, from a nuclear reactor. Particularly, in the present option H2 is obtained by electrolytic water splitting supplying also O2 as a precious by-product in well mature and commercially available already since decades, Light Water Reactors

  12. 26 CFR 48.4041-6 - Application of tax on use of taxable liquid fuel.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... Application of tax on use of taxable liquid fuel. (a) In general—(1) Diesel fuel. (i) If, before April 1, 1983, a person acquires any diesel fuel by any means other than through a transaction subject to tax under section 4041(a)(1) and uses it as a fuel in a diesel powered highway vehicle, the person is liable for...

  13. Fuel sensor-less control of a liquid feed fuel cell under dynamic loading conditions for portable power sources (II)

    NASA Astrophysics Data System (ADS)

    Chang, C. L.; Chen, C. Y.; Sung, C. C.; Liou, D. H.; Chang, C. Y.; Cha, H. C.

    This work presents a new fuel sensor-less control scheme for liquid feed fuel cells that is able to control the supply to a fuel cell system for operation under dynamic loading conditions. The control scheme uses cell-operating characteristics, such as potential, current, and power, to regulate the fuel concentration of a liquid feed fuel cell without the need for a fuel concentration sensor. A current integral technique has been developed to calculate the quantity of fuel required at each monitoring cycle, which can be combined with the concentration regulating process to control the fuel supply for stable operation. As verified by systematic experiments, this scheme can effectively control the fuel supply of a liquid feed fuel cell with reduced response time, even under conditions where the membrane electrolyte assembly (MEA) deteriorates gradually. This advance will aid the commercialization of liquid feed fuel cells and make them more adaptable for use in portable and automotive power units such as laptops, e-bikes, and handicap cars.

  14. TRAJECTORY AND INCINERATION OF ROGUE DROPLETS IN A TURBULENT DIFFUSION FLAME

    EPA Science Inventory

    The trajectory and incineration efficiency of individual droplet streams of a fuel mixture injected into a swirling gas turbulent diffusion flame were measured as a function of droplet size, droplet velocity, interdroplet spacing, and droplet injection angle. Additional experimen...

  15. Vortex-assisted surfactant-enhanced-emulsification liquid-liquid microextraction with solidification of floating organic droplet combined with HPLC for the determination of neonicotinoid pesticides.

    PubMed

    Vichapong, Jitlada; Burakham, Rodjana; Srijaranai, Supalax

    2013-12-15

    A microextraction procedure based on vortex-assisted surfactant-enhanced-emulsification liquid-liquid microextraction with solidification of floating organic droplet (VSLLME-SFO) for preconcentration of neonicotinoid pesticides, including acetamiprid, clotianidin, nitenpyram, imidacloprid, and thiamethoxam, has been developed. In VSLLME-SFO process, the addition of surfactant (as an emulsifier), could be enhance the mass-transfer from the aqueous solution into the extraction solvent. The extraction solvent could be dispersed into the aqueous by vortex process. Other experimental parameters affected the extraction efficiency, including the kind and concentration of salt, concentration and volume of HCl, kind and concentration of surfactant and its volume, kind and volume of extraction solvent, vortex time and the centrifugation extraction time, were also optimized. The optimum extraction conditions of VSLLME-SFO were 10.00 mL of sample, 0.3% (w/v) Na2SO4, 50 µL of 0.050 mol L(-1) SDS, 1.0 mol L(-1) HCl (400 µL), 150 µL of octanol, vortex time 1 min and centrifugation time 10 min. The sediment phase was analyzed by subjecting it to HPLC using a mobile phase of 25% acetonitrile in water, at a flow rate of 1.0 mL min(-1), and photodiode array detection at 254 nm. Under the optimum extraction conditions, high enrichment factors (20-100 fold) and low limit of detection (0.1-0.5 μg L(-1)) could be obtained. This method provided high sensitivity, low toxic organic solvents used, and simplicity of the extraction processes. The proposed method was successfully applied in the analysis of neonicotinoids in fruit juice and water samples. PMID:24209333

  16. 46 CFR 35.30-40 - Flammable liquid and gas fuels as ship's stores-TB/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Flammable liquid and gas fuels as ship's stores-TB/ALL... OPERATIONS General Safety Rules § 35.30-40 Flammable liquid and gas fuels as ship's stores—TB/ALL. Flammable liquids and gases other than diesel fuel, to be used as fuel for approved equipment must satisfy...

  17. Triaxial Swirl Injector Element for Liquid-Fueled Engines

    NASA Technical Reports Server (NTRS)

    Muss, Jeff

    2010-01-01

    A triaxial injector is a single bi-propellant injection element located at the center of the injector body. The injector element consists of three nested, hydraulic swirl injectors. A small portion of the total fuel is injected through the central hydraulic injector, all of the oxidizer is injected through the middle concentric hydraulic swirl injector, and the balance of the fuel is injected through an outer concentric injection system. The configuration has been shown to provide good flame stabilization and the desired fuel-rich wall boundary condition. The injector design is well suited for preburner applications. Preburner injectors operate at extreme oxygen-to-fuel mass ratios, either very rich or very lean. The goal of a preburner is to create a uniform drive gas for the turbomachinery, while carefully controlling the temperature so as not to stress or damage turbine blades. The triaxial injector concept permits the lean propellant to be sandwiched between two layers of the rich propellant, while the hydraulic atomization characteristics of the swirl injectors promote interpropellant mixing and, ultimately, good combustion efficiency. This innovation is suited to a wide range of liquid oxidizer and liquid fuels, including hydrogen, methane, and kerosene. Prototype testing with the triaxial swirl injector demonstrated excellent injector and combustion chamber thermal compatibility and good combustion performance, both at levels far superior to a pintle injector. Initial testing with the prototype injector demonstrated over 96-percent combustion efficiency. The design showed excellent high -frequency combustion stability characteristics with oxygen and kerosene propellants. Unlike the more conventional pintle injector, there is not a large bluff body that must be cooled. The absence of a protruding center body enhances the thermal durability of the triaxial swirl injector. The hydraulic atomization characteristics of the innovation allow the design to be

  18. Alternative Liquid Fuels Simulation Model (AltSim).

    SciTech Connect

    Williams, Ryan; Baker, Arnold Barry; Drennen, Thomas E.

    2009-12-01

    The Alternative Liquid Fuels Simulation Model (AltSim) is a high-level dynamic simulation model which calculates and compares the production and end use costs, greenhouse gas emissions, and energy balances of several alternative liquid transportation fuels. These fuels include: corn ethanol, cellulosic ethanol from various feedstocks (switchgrass, corn stover, forest residue, and farmed trees), biodiesel, and diesels derived from natural gas (gas to liquid, or GTL), coal (coal to liquid, or CTL), and coal with biomass (CBTL). AltSim allows for comprehensive sensitivity analyses on capital costs, operation and maintenance costs, renewable and fossil fuel feedstock costs, feedstock conversion ratio, financial assumptions, tax credits, CO{sub 2} taxes, and plant capacity factor. This paper summarizes the structure and methodology of AltSim, presents results, and provides a detailed sensitivity analysis. The Energy Independence and Security Act (EISA) of 2007 sets a goal for the increased use of biofuels in the U.S., ultimately reaching 36 billion gallons by 2022. AltSim's base case assumes EPA projected feedstock costs in 2022 (EPA, 2009). For the base case assumptions, AltSim estimates per gallon production costs for the five ethanol feedstocks (corn, switchgrass, corn stover, forest residue, and farmed trees) of $1.86, $2.32, $2.45, $1.52, and $1.91, respectively. The projected production cost of biodiesel is $1.81/gallon. The estimates for CTL without biomass range from $1.36 to $2.22. With biomass, the estimated costs increase, ranging from $2.19 per gallon for the CTL option with 8% biomass to $2.79 per gallon for the CTL option with 30% biomass and carbon capture and sequestration. AltSim compares the greenhouse gas emissions (GHG) associated with both the production and consumption of the various fuels. EISA allows fuels emitting 20% less greenhouse gases (GHG) than conventional gasoline and diesels to qualify as renewable fuels. This allows several of the CBTL

  19. Bioconversion of Natural Gas to Liquid Fuel. Opportunities and Challenges

    SciTech Connect

    Fei, Qiang; Guarnieri, Michael T.; Tao, Ling; Laurens, Lieve M. L.; Dowe, Nancy; Pienkos, Philip T.

    2014-05-01

    Natural gas is a mixture of low molecular weight hydrocarbon gases that can be generated from either fossil or anthropogenic resources. Although natural gas is used as a transportation fuel, constraints in storage, relatively low energy content (MJ/L), and delivery have limited widespread adoption. Advanced utilization of natural gas has been explored for biofuel production by microorganisms. In recent years, the aerobic bioconversion of natural gas (or primarily the methane content of natural gas) into liquid fuels (Bio-GTL) by biocatalysts (methanotrophs) has gained increasing attention as a promising alternative for drop-in biofuel production. Moreover, methanotrophic bacteria are capable of converting methane into microbial lipids, which can in turn be converted into renewable diesel via a hydrotreating process. In this paper, biodiversity, catalytic properties and key enzymes and pathways of these microbes are summarized. Bioprocess technologies are discussed based upon existing literature, including cultivation conditions, fermentation modes, bioreactor design, and lipid extraction and upgrading. Our review also outlines the potential of Bio-GTL using methane as an alternative carbon source as well as the major challenges and future research needs of microbial lipid accumulation derived from methane, key performance index, and techno-economic analysis. An analysis of raw material costs suggests that methane-derived diesel fuel has the potential to be competitive with petroleum-derived diesel.

  20. Bioconversion of natural gas to liquid fuel: Opportunities and challenges

    SciTech Connect

    Fei, Q; Guarnieri, MT; Tao, L; Laurens, LML; Dowe, N; Pienkos, PT

    2014-05-01

    Natural gas is a mixture of low molecular weight hydrocarbon gases that can be generated from either fossil or anthropogenic resources. Although natural gas is used as a transportation fuel, constraints in storage, relatively low energy content (MJ/L), and delivery have limited widespread adoption. Advanced utilization of natural gas has been explored for biofuel production by microorganisms. In recent years, the aerobic bioconversion of natural gas (or primarily the methane content of natural gas) into liquid fuels (Bio-GTL) by biocatalysts (methanotrophs) has gained increasing attention as a promising alternative for drop-in biofuel production. Methanotrophic bacteria are capable of converting methane into microbial lipids, which can in turn be converted into renewable diesel via a hydrotreating process. In this paper, biodiversity, catalytic properties and key enzymes and pathways of these microbes are summarized. Bioprocess technologies are discussed based upon existing literature, including cultivation conditions, fermentation modes, bioreactor design, and lipid extraction and upgrading. This review also outlines the potential of Bio-GTL using methane as an alternative carbon source as well as the major challenges and future research needs of microbial lipid accumulation derived from methane, key performance index, and techno-economic analysis. An analysis of raw material costs suggests that methane-derived diesel fuel has the potential to be competitive with petroleum-derived diesel. (C) 2014 The Authors. Published by Elsevier Inc.

  1. Bioconversion of natural gas to liquid fuel: opportunities and challenges.

    PubMed

    Fei, Qiang; Guarnieri, Michael T; Tao, Ling; Laurens, Lieve M L; Dowe, Nancy; Pienkos, Philip T

    2014-01-01

    Natural gas is a mixture of low molecular weight hydrocarbon gases that can be generated from either fossil or anthropogenic resources. Although natural gas is used as a transportation fuel, constraints in storage, relatively low energy content (MJ/L), and delivery have limited widespread adoption. Advanced utilization of natural gas has been explored for biofuel production by microorganisms. In recent years, the aerobic bioconversion of natural gas (or primarily the methane content of natural gas) into liquid fuels (Bio-GTL) by biocatalysts (methanotrophs) has gained increasing attention as a promising alternative for drop-in biofuel production. Methanotrophic bacteria are capable of converting methane into microbial lipids, which can in turn be converted into renewable diesel via a hydrotreating process. In this paper, biodiversity, catalytic properties and key enzymes and pathways of these microbes are summarized. Bioprocess technologies are discussed based upon existing literature, including cultivation conditions, fermentation modes, bioreactor design, and lipid extraction and upgrading. This review also outlines the potential of Bio-GTL using methane as an alternative carbon source as well as the major challenges and future research needs of microbial lipid accumulation derived from methane, key performance index, and techno-economic analysis. An analysis of raw material costs suggests that methane-derived diesel fuel has the potential to be competitive with petroleum-derived diesel.

  2. High pressure droplet burning experiments in reduced gravity

    NASA Technical Reports Server (NTRS)

    Chauveau, Christian; Goekalp, Iskender

    1995-01-01

    A parametric investigation of single droplet gasification regimes is helpful in providing the necessary physical ideas for sub-grid models used in spray combustion numerical prediction codes. A research program has been initiated at the LCSR to explore the vaporization regimes of single and interacting hydrocarbon and liquid oxygen droplets under high pressure conditions. This paper summarizes the status of the LCSR program on the high pressure burning of single fuel droplets; recent results obtained under normal and reduced gravity conditions with suspended droplets are presented. In the work described here, parabolic flights of the CNES Caravelle is used to create a reduced gravity environment of the order of 10(exp -2) g(sub O). For all the droplet burning experiments reported here, the suspended droplet initial diameters are scattered around 1.5 mm; and the ambient air temperature is 300 K. The ambient pressure is varied between 0.1 MPa and 12 MPa. Four fuels are investigated: methanol (Pc = 7.9 MPa), n-heptane (Pc = 2.74 MPa), n-hexane (Pc = 3.01 MPa) and n-octane (Pc = 2.48 MPa).

  3. An enhanced droplet-based liquid microjunction surface sampling system coupled with HPLC-ESI-MS/MS for spatially resolved analysis

    DOE PAGESBeta

    Van Berkel, Gary J.; Weiskittel, Taylor M.; Kertesz, Vilmos

    2014-11-07

    Droplet-based liquid microjunction surface sampling coupled with high-performance liquid chromatography (HPLC)-electrospray ionization (ESI)-tandem mass spectrometry (MS/MS) for spatially resolved analysis provides the possibility of effective analysis of complex matrix samples and can provide a greater degree of chemical information from a single spot sample than is typically possible with a direct analysis of an extract. Described here is the setup and enhanced capabilities of a discrete droplet liquid microjunction surface sampling system employing a commercially available CTC PAL autosampler. The system enhancements include incorporation of a laser distance sensor enabling unattended analysis of samples and sample locations of dramatically disparatemore » height as well as reliably dispensing just 0.5 μL of extraction solvent to make the liquid junction to the surface, wherein the extraction spot size was confined to an area about 0.7 mm in diameter; software modifications improving the spatial resolution of sampling spot selection from 1.0 to 0.1 mm; use of an open bed tray system to accommodate samples as large as whole-body rat thin tissue sections; and custom sample/solvent holders that shorten sampling time to approximately 1 min per sample. Lastly, the merit of these new features was demonstrated by spatially resolved sampling, HPLC separation, and mass spectral detection of pharmaceuticals and metabolites from whole-body rat thin tissue sections and razor blade (“crude”) cut mouse tissue.« less

  4. An enhanced droplet-based liquid microjunction surface sampling system coupled with HPLC-ESI-MS/MS for spatially resolved analysis

    SciTech Connect

    Van Berkel, Gary J.; Weiskittel, Taylor M.; Kertesz, Vilmos

    2014-11-07

    Droplet-based liquid microjunction surface sampling coupled with high-performance liquid chromatography (HPLC)-electrospray ionization (ESI)-tandem mass spectrometry (MS/MS) for spatially resolved analysis provides the possibility of effective analysis of complex matrix samples and can provide a greater degree of chemical information from a single spot sample than is typically possible with a direct analysis of an extract. Described here is the setup and enhanced capabilities of a discrete droplet liquid microjunction surface sampling system employing a commercially available CTC PAL autosampler. The system enhancements include incorporation of a laser distance sensor enabling unattended analysis of samples and sample locations of dramatically disparate height as well as reliably dispensing just 0.5 μL of extraction solvent to make the liquid junction to the surface, wherein the extraction spot size was confined to an area about 0.7 mm in diameter; software modifications improving the spatial resolution of sampling spot selection from 1.0 to 0.1 mm; use of an open bed tray system to accommodate samples as large as whole-body rat thin tissue sections; and custom sample/solvent holders that shorten sampling time to approximately 1 min per sample. Lastly, the merit of these new features was demonstrated by spatially resolved sampling, HPLC separation, and mass spectral detection of pharmaceuticals and metabolites from whole-body rat thin tissue sections and razor blade (“crude”) cut mouse tissue.

  5. Detection of heavy-metal ions using liquid crystal droplet patterns modulated by interaction between negatively charged carboxylate and heavy-metal cations.

    PubMed

    Han, Gyeo-Re; Jang, Chang-Hyun

    2014-10-01

    Herein, we demonstrated a simple, sensitive, and rapid label-free detection method for heavy-metal (HM) ions using liquid crystal (LC) droplet patterns on a solid surface. Stearic-acid-doped LC droplet patterns were spontaneously generated on an n-octyltrichlorosilane (OTS)-treated glass substrate by evaporating a solution of the nematic LC, 4-cyano-4'-pentylbiphenyl (5CB), dissolved in heptane. The optical appearance of the droplet patterns was a dark crossed texture when in contact with air, which represents the homeotropic orientation of the LC. This was caused by the steric interaction between the LC molecules and the alkyl chains of the OTS-treated surface. The dark crossed appearance of the acid-doped LC patterns was maintained after the addition of phosphate buffered saline (PBS) solution (pH 8.1 at 25°C). The deprotonated stearic-acid molecules self-assembled through the LC/aqueous interface, thereby supporting the homeotropic anchoring of 5CB. However, the optical image of the acid-doped LC droplet patterns incubated with PBS containing HM ions appeared bright, indicating a planar orientation of 5CB at the aqueous/LC droplet interface. This dark to bright transition of the LC patterns was caused by HM ions attached to the deprotonated carboxylate moiety, followed by the sequential interruption of the self-assembly of the stearic acid at the LC/aqueous interface. The results showed that the acid-doped LC pattern system not only enabled the highly sensitive detection of HM ions at a sub-nanomolar concentration but it also facilitated rapid detection (<10 min) with simple procedures. PMID:25059128

  6. Detection of heavy-metal ions using liquid crystal droplet patterns modulated by interaction between negatively charged carboxylate and heavy-metal cations.

    PubMed

    Han, Gyeo-Re; Jang, Chang-Hyun

    2014-10-01

    Herein, we demonstrated a simple, sensitive, and rapid label-free detection method for heavy-metal (HM) ions using liquid crystal (LC) droplet patterns on a solid surface. Stearic-acid-doped LC droplet patterns were spontaneously generated on an n-octyltrichlorosilane (OTS)-treated glass substrate by evaporating a solution of the nematic LC, 4-cyano-4'-pentylbiphenyl (5CB), dissolved in heptane. The optical appearance of the droplet patterns was a dark crossed texture when in contact with air, which represents the homeotropic orientation of the LC. This was caused by the steric interaction between the LC molecules and the alkyl chains of the OTS-treated surface. The dark crossed appearance of the acid-doped LC patterns was maintained after the addition of phosphate buffered saline (PBS) solution (pH 8.1 at 25°C). The deprotonated stearic-acid molecules self-assembled through the LC/aqueous interface, thereby supporting the homeotropic anchoring of 5CB. However, the optical image of the acid-doped LC droplet patterns incubated with PBS containing HM ions appeared bright, indicating a planar orientation of 5CB at the aqueous/LC droplet interface. This dark to bright transition of the LC patterns was caused by HM ions attached to the deprotonated carboxylate moiety, followed by the sequential interruption of the self-assembly of the stearic acid at the LC/aqueous interface. The results showed that the acid-doped LC pattern system not only enabled the highly sensitive detection of HM ions at a sub-nanomolar concentration but it also facilitated rapid detection (<10 min) with simple procedures.

  7. Experiments on the dynamics of droplet collisions in a vacuum

    NASA Astrophysics Data System (ADS)

    Willis, K. D.; Orme, M. E.

    Highly controlled experiments of binary droplet collisions in a vacuum environment are performed in order to study the collision dynamics devoid of aerodynamic effects that could otherwise obstruct the experimental observations by causing distortion or even disintegration of the coalesced mass. Pre-collision droplets are generated from capillary stream break-up at wavelengths much larger than those generated with the typical Rayleigh droplet formation in order to reduce the interactions among the collision products. Experimental results show that the range of droplet Weber number necessary to describe the boundaries between permanent coalescence and coalescence followed by separation is several orders of magnitude higher than has been reported in experiments conducted at standard atmospheric pressures with lower viscosity liquids (i.e. hydrocarbon fuels and water). Additionally, the time periods of both the oblate and prolate portions of the coalesced droplet oscillation have been measured and it is reported for the first time that the time period for the prolate portion of the oscillation grows exponentially with the Weber number. Finally, new pictorial results are presented for droplet collisions between non-spherical droplets.

  8. The Transformation of Solid Atmospheric Particles into Liquid Droplets Through Heterogeneous Chemistry: Laboratory Insights into the Processing of Calcium Containing Mineral Dust Aerosol in the Troposphere

    SciTech Connect

    Krueger, Brenda J.; Grassian, Vicki H.; Laskin, Alexander; Cowin, James P.

    2003-02-15

    [1] Individual calcium carbonate particles reacted with gas- phase nitric acid at 293 K have been followed using Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray (EDX) analysis as a function of time and relative humidity (RH). The rate of calcium carbonate to calcium nitrate conversion is significantly enhanced in the presence of water vapor. The SEM images clearly show that solid CaCO3 particles are converted to spherical droplets as the reaction proceeds. The process occurs through a two-step mechanism involving the conversion of calcium carbonate into calcium nitrate followed by the deliquescence of the calcium nitrate product. The change in phase of the particles and the significant reactivity of nitric acid and CaCO3 at low RH are a direct result of the deliquescence of the product at low RH. This is the first laboratory study to show the phase transformation of solid particles into liquid droplets through heterogeneous chemistry.

  9. Evaporation of a sessile liquid droplet from the shear or flexural surfaces of a quartz tuning fork

    NASA Astrophysics Data System (ADS)

    Jung, Namchul; Yun, Minhyuk; Jeon, Sangmin

    2013-08-01

    A piezoelectric quartz tuning fork (QTF) has been used to investigate the evaporation of a sessile water droplet with nanogram sensitivity. A water droplet is placed on one facet of a QTF tine and the changes in the resonance frequency and dissipation factor, which are related to the changes in mass and viscous damping, respectively, are measured in situ during the evaporation. Depending on the facet of the QTF tine on which the water droplet is placed, the changes in the frequency and dissipation factor arise in different vibration modes: the flexural or shear modes. The shear mode measurement is affected by the penetration depth, so changes in the frequency and dissipation factor are observed only when the water droplet is sufficiently thin, whereas the changes in the flexural mode measurements are observed during the entire evaporation process. When a droplet of polystyrene nanoparticle suspension is evaporated from the flexural surface, the concentration of the nanoparticle suspension can be determined from the difference in mass between the initial droplet and the dry nanoparticles. In contrast, changes in the physical properties of the suspension are obtained in situ from the evaporation from the shear surface. These results demonstrate that QTFs are useful tools for the investigation of the evaporation of suspensions from solid surfaces.

  10. Low-Emissions Burner Technology using Biomass-Derived Liquid Fuels

    SciTech Connect

    2010-07-01

    The University of Alabama will develop fuel-flexible, low-emissions burner technology for the metal processing industry that is capable of using biomass-derived liquid fuels, such as glycerin or fatty acids, as a substitute for natural gas. By replacing a fossil fuel with biomass fuels, this new burner will enable a reduction in energy consumption and greenhouse gas emissions and an increase in fuel flexibility.

  11. Serial biological conversion of coal into liquid fuels

    SciTech Connect

    Liu, R.Q.; Johnson, N.L.; Magruder, G.C.; Ackerson, M.D.; Vega, J.L.; Clausen, E.C.; Gaddy, J.L.

    1988-01-01

    Recently, several microorganisms have been shown to be capable of directly solubilizing low rank coals. This bioextract has a high molecular weight and is water soluble, but is not useful as a liquid fuel. This paper presents the results of studies to biologically convert the solubilized coal into more useful compounds. Preliminary experiments have been conducted to isolate cultures for the serial biological conversion of coal into alcohols. Coal particles have been solubilized employing an isolate from the surface of Arkansas lignite. Natural inocula, such as sheep rumen and sewage sludge, are then employed in developing cultures for converting the bioextract into alcohols. This paper presents preliminary results of experiments in coal solubilization and bioextract conversion.

  12. Nonlinear longitudinal oscillations of fuel in rockets feed lines with gas-liquid damper

    NASA Astrophysics Data System (ADS)

    Avramov, K. V.; Filipkovsky, S.; Tonkonogenko, A. M.; Klimenko, D. V.

    2016-03-01

    The mathematical model of the fuel oscillations in the rockets feed lines with gas-liquid dampers is derived. The nonlinear model of the gas-liquid damper is suggested. The vibrations of fuel in the feed lines with the gas-liquid dampers are considered nonlinear. The weighted residual method is applied to obtain the finite degrees of freedom nonlinear model of the fuel oscillations. Shaw-Pierre nonlinear normal modes are applied to analyze free vibrations. The forced oscillations of the fuel at the principle resonances are analyzed. The stability of the forced oscillations is investigated. The results of the forced vibrations analysis are shown on the frequency responses.

  13. Control of initiation, rate, and routing of spontaneous capillary-driven flow of liquid droplets through microfluidic channels on SlipChip.

    PubMed

    Pompano, Rebecca R; Platt, Carol E; Karymov, Mikhail A; Ismagilov, Rustem F

    2012-01-24

    This Article describes the use of capillary pressure to initiate and control the rate of spontaneous liquid-liquid flow through microfluidic channels. In contrast to flow driven by external pressure, flow driven by capillary pressure is dominated by interfacial phenomena and is exquisitely sensitive to the chemical composition and geometry of the fluids and channels. A stepwise change in capillary force was initiated on a hydrophobic SlipChip by slipping a shallow channel containing an aqueous droplet into contact with a slightly deeper channel filled with immiscible oil. This action induced spontaneous flow of the droplet into the deeper channel. A model predicting the rate of spontaneous flow was developed on the basis of the balance of net capillary force with viscous flow resistance, using as inputs the liquid-liquid surface tension, the advancing and receding contact angles at the three-phase aqueous-oil-surface contact line, and the geometry of the devices. The impact of contact angle hysteresis, the presence or absence of a lubricating oil layer, and adsorption of surface-active compounds at liquid-liquid or liquid-solid interfaces were quantified. Two regimes of flow spanning a 10(4)-fold range of flow rates were obtained and modeled quantitatively, with faster (mm/s) flow obtained when oil could escape through connected channels as it was displaced by flowing aqueous solution, and slower (micrometer/s) flow obtained when oil escape was mostly restricted to a micrometer-scale gap between the plates of the SlipChip ("dead-end flow"). Rupture of the lubricating oil layer (reminiscent of a Cassie-Wenzel transition) was proposed as a cause of discrepancy between the model and the experiment. Both dilute salt solutions and complex biological solutions such as human blood plasma could be flowed using this approach. We anticipate that flow driven by capillary pressure will be useful for the design and operation of flow in microfluidic applications that do not

  14. Molecular dynamics analysis of multiphase interfaces based on in situ extraction of the pressure distribution of a liquid droplet on a solid surface.

    PubMed

    Nishida, S; Surblys, D; Yamaguchi, Y; Kuroda, K; Kagawa, M; Nakajima, T; Fujimura, H

    2014-02-21

    Molecular dynamics simulations of a nanoscale liquid droplet on a solid surface are carried out in order to examine the pressure tensor field around the multiphase interfaces, and to explore the validity of Young's equation. By applying the virial theorem to a hemicylindrical droplet consisting of argon molecules on a solid surface, two-dimensional distribution of the pressure tensor is obtained. Tensile principal pressure tangential to the interface is observed around the liquid-vapor transition layer, while both tensile and compressive principal pressure tangential to the interface exists around the solid-liquid transition layer due to the inhomogeneous density distribution. The two features intermix inside the overlap region between the transition layers at the contact line. The contact angle is evaluated by using a contour line of the maximum principal pressure difference. The interfacial tensions are calculated by using Bakker's equation and Young-Laplace equation to the pressure tensor distribution. The relation between measured contact angle and calculated interfacial tensions turns out to be consistent with Young's equation, which is known as the description of the force balance at the three-phase interface.

  15. Molecular dynamics analysis of multiphase interfaces based on in situ extraction of the pressure distribution of a liquid droplet on a solid surface.

    PubMed

    Nishida, S; Surblys, D; Yamaguchi, Y; Kuroda, K; Kagawa, M; Nakajima, T; Fujimura, H

    2014-02-21

    Molecular dynamics simulations of a nanoscale liquid droplet on a solid surface are carried out in order to examine the pressure tensor field around the multiphase interfaces, and to explore the validity of Young's equation. By applying the virial theorem to a hemicylindrical droplet consisting of argon molecules on a solid surface, two-dimensional distribution of the pressure tensor is obtained. Tensile principal pressure tangential to the interface is observed around the liquid-vapor transition layer, while both tensile and compressive principal pressure tangential to the interface exists around the solid-liquid transition layer due to the inhomogeneous density distribution. The two features intermix inside the overlap region between the transition layers at the contact line. The contact angle is evaluated by using a contour line of the maximum principal pressure difference. The interfacial tensions are calculated by using Bakker's equation and Young-Laplace equation to the pressure tensor distribution. The relation between measured contact angle and calculated interfacial tensions turns out to be consistent with Young's equation, which is known as the description of the force balance at the three-phase interface. PMID:24559360

  16. Analytical modeling of operating characteristics of premixing-prevaporizing fuel-air mixing passages. Volume 1: Analysis and results

    NASA Technical Reports Server (NTRS)

    Anderson, O. L.; Chiappetta, L. M.; Edwards, D. E.; Mcvey, J. B.

    1982-01-01

    A model for predicting the distribution of liquid fuel droplets and fuel vapor in premixing-prevaporizing fuel-air mixing passages of the direct injection type is reported. This model consists of three computer programs; a calculation of the two dimensional or axisymmetric air flow field neglecting the effects of fuel; a calculation of the three dimensional fuel droplet trajectories and evaporation rates in a known, moving air flow; a calculation of fuel vapor diffusing into a moving three dimensional air flow with source terms dependent on the droplet evaporation rates. The fuel droplets are treated as individual particle classes each satisfying Newton's law, a heat transfer, and a mass transfer equation. This fuel droplet model treats multicomponent fuels and incorporates the physics required for the treatment of elastic droplet collisions, droplet shattering, droplet coalescence and droplet wall interactions. The vapor diffusion calculation treats three dimensional, gas phase, turbulent diffusion processes. The analysis includes a model for the autoignition of the fuel air mixture based upon the rate of formation of an important intermediate chemical species during the preignition period.

  17. Cloud Droplet Size and Liquid Water Path Retrievals From Zenith Radiance Measurements: Examples From the Atmospheric Radiation Measurement Program and the Aerosol Robotic Network

    NASA Technical Reports Server (NTRS)

    Chiu, J. C.; Marshak, A.; Huang, C.-H.; Varnai, T.; Hogan, R. J.; Giles, D. M.; Holben, B. N.; Knyazikhin, Y.; O'Connor, E. J.; Wiscombe, W. J.

    2012-01-01

    The ground-based Atmospheric Radiation Measurement Program (ARM) and NASA Aerosol Robotic Network (AERONET) routinely monitor clouds using zenith radiances at visible and near-infrared wavelengths. Using the transmittance calculated from such measurements, we have developed a new retrieval method for cloud effective droplet size and conducted extensive tests for non-precipitating liquid water clouds. The underlying principle is to combine a water-absorbing wavelength (i.e. 1640 nm) with a nonwater-absorbing wavelength for acquiring information on cloud droplet size and optical depth. For simulated stratocumulus clouds with liquid water path less than 300 g/sq m and horizontal resolution of 201m, the retrieval method underestimates the mean effective radius by 0.8 m, with a root-mean-squared error of 1.7 m and a relative deviation of 13 %. For actual observations with a liquid water path less than 450 gm.2 at the ARM Oklahoma site during 2007-2008, our 1.5 min-averaged retrievals are generally larger by around 1 m than those from combined ground-based cloud radar and microwave radiometer at a 5min temporal resolution. We also compared our retrievals to those from combined shortwave flux and microwave observations for relatively homogeneous clouds, showing that the bias between these two retrieval sets is negligible, but the error of 2.6 m and the relative deviation of 22% are larger than those found in our simulation case. Finally, the transmittance-based cloud effective droplet radii agree to better than 11% with satellite observations and have a negative bias of 1 m. Overall, the retrieval method provides reasonable cloud effective radius estimates, which can enhance the cloud products of both ARM and AERONET.

  18. LIQUID NATURAL GAS (LNG): AN ALTERNATIVE FUEL FROM LANDFILL GAS (LFG) AND WASTEWATER DIGESTER GAS

    SciTech Connect

    VANDOR,D.

    1999-03-01

    This Research and Development Subcontract sought to find economic, technical and policy links between methane recovery at landfill and wastewater treatment sites in New York and Maryland, and ways to use that methane as an alternative fuel--compressed natural gas (CNG) or liquid natural gas (LNG) -- in centrally fueled Alternative Fueled Vehicles (AFVs).

  19. Combustion experiments in reduced gravity with two-component miscible droplets

    NASA Technical Reports Server (NTRS)

    Shaw, Benjamin D.; Aharon, Israel

    1993-01-01

    The combustion of liquid fuels is a topic worthy of scientific attention on practical and fundamental grounds. Most practical applications of liquid-fuel combustion involve the formation of spray diffusion flames, where droplets frequently burn in groups rather than individually. The combustion is typically complex, with interactions occurring between various physical mechanisms. Many efforts to understand liquid sprays have focused upon studying isolated droplets. Information gained from these studies is often not directly transferable to spray situations. However, isolated-droplet studies are useful in that they allow certain phenomena (e.g., extinction) to be studied under well-controlled and simplified conditions. When theory and experiment agree for simplified situations, predictions for more complex cases (where accurate experimental data may not exist) may be made with more confidence. The simplest droplet combustion scenario is that of an isolated droplet undergoing spherically-symmetric combustion in an environment of infinite extent. The idealization is approached only when forced and buoyant convection are negligible, the droplet is unsupported, and all foreign objects are far-removed from the combustion zone. Appreciable gravity levels compromise spherical symmetry by inducing buoyant convection.

  20. Dispersive solid-phase extraction followed by vortex-assisted dispersive liquid-liquid microextraction based on the solidification of a floating organic droplet for the determination of benzoylurea insecticides in soil and sewage sludge.

    PubMed

    Peng, Guilong; He, Qiang; Mmereki, Daniel; Lu, Ying; Zhong, Zhihui; Liu, Hanyang; Pan, Weiliang; Zhou, Guangming; Chen, Junhua

    2016-04-01

    A novel dispersive solid-phase extraction combined with vortex-assisted dispersive liquid-liquid microextraction based on solidification of floating organic droplet was developed for the determination of eight benzoylurea insecticides in soil and sewage sludge samples before high-performance liquid chromatography with ultraviolet detection. The analytes were first extracted from the soil and sludge samples into acetone under optimized pretreatment conditions. Clean-up of the extract was conducted by dispersive solid-phase extraction using activated carbon as the sorbent. The vortex-assisted dispersive liquid-liquid microextraction based on solidification of floating organic droplet procedure was performed by using 1-undecanol with lower density than water as the extraction solvent, and the acetone contained in the solution also acted as dispersive solvent. Under the optimum conditions, the linearity of the method was in the range 2-500 ng/g with correlation coefficients (r) of 0.9993-0.9999. The limits of detection were in the range of 0.08-0.56 ng/g. The relative standard deviations varied from 2.16 to 6.26% (n = 5). The enrichment factors ranged from 104 to 118. The extraction recoveries ranged from 81.05 to 97.82% for all of the analytes. The good performance has demonstrated that the proposed methodology has a strong potential for application in the multiresidue analysis of complex matrices. PMID:26888089