Modeling of zero gravity venting: Studies of two-phase heat transfer under reduced gravity

NASA Technical Reports Server (NTRS)

Merte, H., Jr.

1986-01-01

The objective is to predict the pressure response of a saturated liquid-vapor system when undergoing a venting or depressurization process in zero gravity at low vent rates. An experimental investigation of the venting of cylindrical containers partially filled with initially saturated liquids was previously conducted under zero-gravity conditions and compared with an analytical model which incorporated the effect of interfacial mass transfer on the ullage pressure response during venting. A new model is presented to improve the estimation of the interfacial mass transfer. Duhammel's superposition integral is incorporated to approximate the transient temperature response of the interface, treating the liquid as a semi-infinite solid with conduction heat transfer. Account is also taken of the condensation taking place within the bulk of a saturated vapor as isentropic expansion takes place. Computational results are presented for the venting of R-11 from a given vessel and initial state for five different venting rates over a period of three seconds, and compared to prior NASA experiments. An improvement in the prediction of the final pressure takes place, but is still considerably below the measurements.

Numerical modelling and experimental study of liquid evaporation during gel formation

NASA Astrophysics Data System (ADS)

Pokusaev, B. G.; Khramtsov, D. P.

2017-11-01

Gels are promising materials in biotechnology and medicine as a medium for storing cells for bioprinting applications. Gel is a two-phase system consisting of solid medium and liquid phase. Understanding of a gel structure evolution and gel aging during liquid evaporation is a crucial step in developing new additive bioprinting technologies. A numerical and experimental study of liquid evaporation was performed. In experimental study an evaporation process of an agarose gel layer located on Petri dish was observed and mass difference was detected using electronic scales. Numerical model was based on a smoothed particle hydrodynamics method. Gel in a model was represented as a solid-liquid system and liquid evaporation was modelled due to capillary forces and heat transfer. Comparison of experimental data and numerical results demonstrated that model can adequately represent evaporation process in agarose gel.

Scrap melting model for steel converter founded on interfacial solid/liquid phenomena

NASA Astrophysics Data System (ADS)

Kruskopf, Ari; Holappa, Lauri

2017-12-01

The primary goal in steel converter operation is the removal of carbon from the hot metal. This is achieved by blowing oxygen into the melt. The oxidation of carbon produces a lot of heat. To avoid too high temperatures in the melt cold scrap (recycled steel) is charged into the converter. The melting rate is affected by heat and carbon mass transfer. A process model for steel converter is in development. This model is divided into several modules, which are fluid dynamics, heat- and mass-transfer, scrap melting and chemical reactions. This article focuses on the development of the scrap melting module. A numerical model for calculating temperature and carbon concentration in the melt is presented. The melt model is connected with the solid scrap model via solid/liquid interface. The interface model can take into account solidification of iron melt, melting of solidified layer, a situation without such phase changes, and scrap melting. The aim is to predict the melting rate of the scrap including the properties of the hot metal. The model is tested by calculating the melting rates for different scrap thicknesses. All of the stages in the interface model were taking place in the test calculations.

Analysis of pressure spectra measurements in a ducted combustion system. Ph.D. Thesis - Toledo Univ.

NASA Technical Reports Server (NTRS)

Miles, J. H.

1980-01-01

Combustion noise propagation in an operating ducted liquid fuel combustion system is studied in relation to the development of combustion noise prediction and suppression techniques. The presence of combustor emissions in the duct is proposed as the primary mechanism producing the attenuation and dispersion of combustion noise propagating in an operating liquid fuel combustion system. First, a complex mathematical model for calculating attenuation and dispersion taking into account mass transfer, heat transfer, and viscosity effects due to the presence of liquid fuel droplets or solid soot particles is discussed. Next, a simpler single parameter model for calculating pressure auto-spectra and cross-spectra which takes into account dispersion and attenuation due to heat transfer between solid soot particles and air is developed. Then, auto-spectra and cross-spectra obtained from internal pressure measurements in a combustion system consisting of a J-47 combustor can, a spool piece, and a long duct are presented. Last, analytical results obtained with the single parameter model are compared with the experimental measurements. The single parameter model results are shown to be in excellent agreement with the measurements.

Analysis of pressure spectra measurements in a ducted combustion system

NASA Astrophysics Data System (ADS)

Miles, J. H.

1980-11-01

Combustion noise propagation in an operating ducted liquid fuel combustion system is studied in relation to the development of combustion noise prediction and suppression techniques. The presence of combustor emissions in the duct is proposed as the primary mechanism producing the attenuation and dispersion of combustion noise propagating in an operating liquid fuel combustion system. First, a complex mathematical model for calculating attenuation and dispersion taking into account mass transfer, heat transfer, and viscosity effects due to the presence of liquid fuel droplets or solid soot particles is discussed. Next, a simpler single parameter model for calculating pressure auto-spectra and cross-spectra which takes into account dispersion and attenuation due to heat transfer between solid soot particles and air is developed. Then, auto-spectra and cross-spectra obtained from internal pressure measurements in a combustion system consisting of a J-47 combustor can, a spool piece, and a long duct are presented. Last, analytical results obtained with the single parameter model are compared with the experimental measurements. The single parameter model results are shown to be in excellent agreement with the measurements.

Characterization of simultaneous heat and mass transfer phenomena for water vapour condensation on a solid surface in an abiotic environment--application to bioprocesses.

PubMed

Tiwari, Akhilesh; Kondjoyan, Alain; Fontaine, Jean-Pierre

2012-07-01

The phenomenon of heat and mass transfer by condensation of water vapour from humid air involves several key concepts in aerobic bioreactors. The high performance of bioreactors results from optimised interactions between biological processes and multiphase heat and mass transfer. Indeed in various processes such as submerged fermenters and solid-state fermenters, gas/liquid transfer need to be well controlled, as it is involved at the microorganism interface and for the control of the global process. For the theoretical prediction of such phenomena, mathematical models require heat and mass transfer coefficients. To date, very few data have been validated concerning mass transfer coefficients from humid air inflows relevant to those bioprocesses. Our study focussed on the condensation process of water vapour and developed an experimental set-up and protocol to study the velocity profiles and the mass flux on a small size horizontal flat plate in controlled environmental conditions. A closed circuit wind tunnel facility was used to control the temperature, hygrometry and hydrodynamics of the flow. The temperature of the active surface was controlled and kept isothermal below the dew point to induce condensation, by the use of thermoelectricity. The experiments were performed at ambient temperature for a relative humidity between 35-65% and for a velocity of 1.0 ms⁻¹. The obtained data are analysed and compared to available theoretical calculations on condensation mass flux.

Mucous solids and liquid secretion by airways: studies with normal pig, cystic fibrosis human, and non-cystic fibrosis human bronchi

PubMed Central

Martens, Chelsea J.; Inglis, Sarah K.; Valentine, Vincent G.; Garrison, Jennifer; Conner, Gregory E.

2011-01-01

To better understand how airways produce thick airway mucus, nonvolatile solids were measured in liquid secreted by bronchi from normal pig, cystic fibrosis (CF) human, and non-CF human lungs. Bronchi were exposed to various secretagogues and anion secretion inhibitors to induce a range of liquid volume secretion rates. In all three groups, the relationship of solids concentration (percent nonvolatile solids) to liquid volume secretion rate was curvilinear, with higher solids concentration associated with lower rates of liquid volume secretion. In contrast, the secretion rates of solids mass and water mass as functions of liquid volume secretion rates exhibited positive linear correlations. The y-intercepts of the solids mass-liquid volume secretion relationships for all three groups were positive, thus accounting for the higher solids concentrations in airway liquid at low rates of secretion. Predictive models derived from the solids mass and water mass linear equations fit the experimental percent solids data for the three groups. The ratio of solids mass secretion to liquid volume secretion was 5.2 and 2.4 times higher for CF bronchi than for pig and non-CF bronchi, respectively. These results indicate that normal pig, non-CF human, and CF human bronchi produce a high-percent-solids mucus (>8%) at low rates of liquid volume secretion (≤1.0 μl·cm−2·h−1). However, CF bronchi produce mucus with twice the percent solids (∼8%) of pig or non-CF human bronchi at liquid volume secretion rates ≥4.0 μl·cm−2·h−1. PMID:21622844

Hydrogen slush density reference system

NASA Technical Reports Server (NTRS)

Weitzel, D. H.; Lowe, L. T.; Ellerbruch, D. A.; Cruz, J. E.; Sindt, C. F.

1971-01-01

A hydrogen slush density reference system was designed for calibration of field-type instruments and/or transfer standards. The device is based on the buoyancy principle of Archimedes. The solids are weighed in a low-mass container so arranged that solids and container are buoyed by triple-point liquid hydrogen during the weighing process. Several types of hydrogen slush density transducers were developed and tested for possible use as transfer standards. The most successful transducers found were those which depend on change in dielectric constant, after which the Clausius-Mossotti function is used to relate dielectric constant and density.

Enhancing heat capacity of colloidal suspension using nanoscale encapsulated phase-change materials for heat transfer.

PubMed

Hong, Yan; Ding, Shujiang; Wu, Wei; Hu, Jianjun; Voevodin, Andrey A; Gschwender, Lois; Snyder, Ed; Chow, Louis; Su, Ming

2010-06-01

This paper describes a new method to enhance the heat-transfer property of a single-phase liquid by adding encapsulated phase-change nanoparticles (nano-PCMs), which absorb thermal energy during solid-liquid phase changes. Silica-encapsulated indium nanoparticles and polymer-encapsulated paraffin (wax) nanoparticles have been made using colloid method, and suspended into poly-alpha-olefin (PAO) and water for potential high- and low-temperature applications, respectively. The shells prevent leakage and agglomeration of molten phase-change materials, and enhance the dielectric properties of indium nanoparticles. The heat-transfer coefficients of PAO containing indium nanoparticles (30% by mass) and water containing paraffin nanoparticles (10% by mass) are 1.6 and 1.75 times higher than those of corresponding single-phase fluids. The structural integrity of encapsulation allows repeated use of such nanoparticles for many cycles in high heat generating devices.

Development of a fully integrated falling film microreactor for gas-liquid-solid biotransformation with surface immobilized O2 -dependent enzyme.

PubMed

Bolivar, Juan M; Krämer, Christina E M; Ungerböck, Birgit; Mayr, Torsten; Nidetzky, Bernd

2016-09-01

Microstructured flow reactors are powerful tools for the development of multiphase biocatalytic transformations. To expand their current application also to O2 -dependent enzymatic conversions, we have implemented a fully integrated falling film microreactor that provides controllable countercurrent gas-liquid phase contacting in a multi-channel microstructured reaction plate. Advanced non-invasive optical sensing is applied to measure liquid-phase oxygen concentrations in both in- and out-flow as well as directly in the microchannels (width: 600 μm; depth: 200 μm). Protein-surface interactions are designed for direct immobilization of catalyst on microchannel walls. Target enzyme (here: d-amino acid oxidase) is fused to the positively charged mini-protein Zbasic2 and the channel surface contains a negatively charged γ-Al2 O3 wash-coat layer. Non-covalent wall attachment of the chimeric Zbasic2 _oxidase resulted in fully reversible enzyme immobilization with fairly uniform surface coverage and near complete retention of biological activity. The falling film at different gas and liquid flow rates as well as reactor inclination angles was shown to be mostly wavy laminar. The calculated film thickness was in the range 0.5-1.3 × 10(-4)  m. Direct O2 concentration measurements at the channel surface demonstrated that the liquid side mass transfer coefficient (KL ) for O2 governed the overall gas/liquid/solid mass transfer and that the O2 transfer rate (≥0.75 mM · s(-1) ) vastly exceeded the maximum enzymatic reaction rate in a wide range of conditions. A value of 7.5 (±0.5) s(-1) was determined for the overall mass transfer coefficient KL a, comprising a KL of about 7 × 10(-5)  m · s(-1) and a specific surface area of up to 10(5)  m(-1) . Biotechnol. Bioeng. 2016;113: 1862-1872. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

SOLID-LIQUID PHASE TRANSFER CATALYZED SYNTHESIS OF CINNAMYL ACETATE-KINETICS AND ANALYSIS OF FACTORS AFFECTING THE REACTION IN A BATCH REACTOR

EPA Science Inventory

The use of solid-liquid phase transfer catalysis has an advantage of carrying out reaction between two immiscible substrates, one in solid phase and the other in liquid phase, with high selectivity and at relatively low temperatures. In this study we investigated the synthesis ci...

Modeling Gas-Particle Partitioning of SOA: Effects of Aerosol Physical State and RH

NASA Astrophysics Data System (ADS)

Zuend, A.; Seinfeld, J.

2011-12-01

Aged tropospheric aerosol particles contain mixtures of inorganic salts, acids, water, and a large variety of organic compounds. In liquid aerosol particles non-ideal mixing of all species determines whether the condensed phase undergoes liquid-liquid phase separation or whether it is stable in a single mixed phase, and whether it contains solid salts in equilibrium with their saturated solution. The extended thermodynamic model AIOMFAC is able to predict such phase states by representing the variety of organic components using functional groups within a group-contribution concept. The number and composition of different condensed phases impacts the diversity of reaction media for multiphase chemistry and the gas-particle partitioning of semivolatile species. Recent studies show that under certain conditions biogenic and other organic-rich particles can be present in a highly viscous, semisolid or amorphous solid physical state, with consequences regarding reaction kinetics and mass transfer limitations. We present results of new gas-particle partitioning computations for aerosol chamber data using a model based on AIOMFAC activity coefficients and state-of-the-art vapor pressure estimation methods. Different environmental conditions in terms of temperature, relative humidity (RH), salt content, amount of precursor VOCs, and physical state of the particles are considered. We show how modifications of absorptive and adsorptive gas-particle mass transfer affects the total aerosol mass in the calculations and how the results of these modeling approaches compare to data of aerosol chamber experiments, such as alpha-pinene oxidation SOA. For a condensed phase in a mixed liquid state containing ammonium sulfate, the model predicts liquid-liquid phase separation up to high RH in case of, on average, moderately hydrophilic organic compounds, such as first generation oxidation products of alpha-pinene. The computations also reveal that treating liquid phases as ideal mixtures substantially overestimates the SOA mass, especially at high relative humidity.

Transfer behavior of odorous pollutants in wastewater sludge system under typical chemical conditioning processes for dewaterability enhancement.

PubMed

Gao, Hongyu; Zhang, Weijun; Song, Zhenzhen; Yang, Xiaofang; Yang, Lian; Cao, Mengdi; Wang, Dongsheng; Liao, Guiying

2017-06-13

Chemical conditioning has been used for enhancing wastewater sludge dewaterability for many years, but the characteristics of odorous pollutants emission in sludge conditioning were still unclear. In this work, the transfer behavior of different odorous pollutants between air, liquid and solid phases under typical chemical conditioning processes for high-pressure dewatering was systematically investigated. The results indicated that that besides hydrogen sulfide (H 2 S) and ammonia (NH 3 ), 21 kinds of volatile organic contaminants (VOCs) were identified and quantified by gas chromatography-mass spectrometry (GC-MS), while the concentrations and composition of odorous pollutants varied greatly for different conditioning processes. VOCs were composed by three main constituents including benzenes, halogeno benzene and hydrocarbons. According to mass balance analysis, about 50% of VOCs adsorbed within sludge extracellular polymeric substances (EPS) fraction. Since EPS was damaged and/or flocculation in different chemical conditioning processes, VOCs distributed in solid phase transformed into liquid phase and then released into air. The discrepancies in mass of odorous pollutants before and after chemical conditioning were likely to be related to chemical conversion under acidification, oxidation and precipitation in the presence of ferric ions.

Bio-inspired Murray materials for mass transfer and activity

NASA Astrophysics Data System (ADS)

Zheng, Xianfeng; Shen, Guofang; Wang, Chao; Li, Yu; Dunphy, Darren; Hasan, Tawfique; Brinker, C. Jeffrey; Su, Bao-Lian

2017-04-01

Both plants and animals possess analogous tissues containing hierarchical networks of pores, with pore size ratios that have evolved to maximize mass transport and rates of reactions. The underlying physical principles of this optimized hierarchical design are embodied in Murray's law. However, we are yet to realize the benefit of mimicking nature's Murray networks in synthetic materials due to the challenges in fabricating vascularized structures. Here we emulate optimum natural systems following Murray's law using a bottom-up approach. Such bio-inspired materials, whose pore sizes decrease across multiple scales and finally terminate in size-invariant units like plant stems, leaf veins and vascular and respiratory systems provide hierarchical branching and precise diameter ratios for connecting multi-scale pores from macro to micro levels. Our Murray material mimics enable highly enhanced mass exchange and transfer in liquid-solid, gas-solid and electrochemical reactions and exhibit enhanced performance in photocatalysis, gas sensing and as Li-ion battery electrodes.

ON-SITE SOLID-PHASE EXTRACTION AND LABORATORY ...

EPA Pesticide Factsheets

Fragrance materials such as synthetic musks in aqueous samples, are normally determined by gas chromatography/mass spectrometry in the selected ion monitoring (SIM) mode to provide maximum sensitivity after liquid-liquid extraction of I -L samples. Full-scan mass spectra are required to verify that a target analyte has been found by comparison with the mass spectra of fragrance compounds in the NIST mass spectral library. A I -L sample usually provides insufficient analyte for full scan data acquisition. This paper describes an on-site extraction method developed at the U.S. Environmental Protection Agency (USEPA)- Las Vegas Nevada - for synthetic musks from 60 L of wastewater effluent. Such a large sample volume permits high-quality, full-scan mass spectra to be obtained for a wide array of synthetic musks. Quantification of these compounds was achieved from the full-scan data directly, without the need to acquire SIM data. The detection limits obtained with this method are an order of magnitude lower than those obtained from liquid-liquid and other solid phase extraction methods. This method is highly reproducible, and recoveries ranged from 80 to 97% in spiked sewage treatment plant effluent. The high rate of sorbent-sample mass transfer eliminated the need for a methanolic activation step, which reduced extraction time, labor, and solvent use, More samples could be extracted in the field at lower cost. After swnple extraction, the light- weight cartridges ar

Apparatus for leaching core material from clad nuclear fuel pin segments

DOEpatents

Yarbro, Orlan O.

1980-01-01

This invention relates to improved apparatus for counter-currently contacting liquids and solids to dissolve, or leach, a selected component of the solids while minimizing back-mixing of the liquid phase. The apparatus includes an elongated drum which is rotatable about its longitudinal axis in either direction and is partitioned radially into a solids-inlet/liquid-outlet compartment at one end, a solids-outlet/liquid-inlet compartment at its other end, and leaching compartments therebetween. The drum is designed to operate with its acid-inlet end elevated and with the longitudinal axis of the drum at an angle in the range of from about 3.degree. to 14.degree. to the horizontal. Each leaching compartment contains a chute assembly for advancing solids into the next compartment in the direction of solids flow when the drum is rotated in a selected direction. The chute assembly includes a solids-transfer baffle and a chute in the form of a slotted, skewed, conical frustum portion. When the drum is rotated in the direction opposite to that effecting solids transfer, the solids-transfer baffles continually separate and re-mix the solids and liquids in their respective compartments. The partitions defining the leaching compartments are formed with corresponding outer, annular, imperforate regions, each region extending inwardly from the partition rim to an annular array of perforations concentric with the rim. In each leaching compartment, the spacing between the rim and the perforations determines the depth of liquid at the liquid-outlet end of the compartment. The liquid input to the drum assembly flows continuously through the compartments, preventing back-mixing due to density differences, whereas backflow due to waves generated by the solids-transfer baffles is virtually eliminated because of the tilted orientation of the drum assembly.

Mass balance evaluation of polybrominated diphenyl ethers in landfill leachate and potential for transfer from e-waste.

PubMed

Danon-Schaffer, Monica N; Mahecha-Botero, Andrés; Grace, John R; Ikonomou, Michael

2013-09-01

Previous research on brominated flame retardants (BFRs), including polybrominated diphenyl ethers (PBDEs) has largely focussed on their concentrations in the environment and their adverse effects on human health. This paper explores their transfer from waste streams to water and soil. A comprehensive mass balance model is developed to track polybrominated diphenyl ethers (PBDEs), originating from e-waste and non-e-waste solids leaching from a landfill. Stepwise debromination is assumed to occur in three sub-systems (e-waste, aqueous leachate phase, and non-e-waste solids). Analysis of landfill samples and laboratory results from a solid-liquid contacting chamber are used to estimate model parameters to simulate an urban landfill system, for past and future scenarios. Sensitivity tests to key model parameters were conducted. Lower BDEs require more time to disappear than high-molecular weight PBDEs, since debromination takes place in a stepwise manner, according to the simplified reaction scheme. Interphase mass transfer causes the decay pattern to be similar in all three sub-systems. The aqueous phase is predicted to be the first sub-system to eliminate PBDEs if their input to the landfill were to be stopped. The non-e-waste solids would be next, followed by the e-waste sub-system. The model shows that mass transfer is not rate-limiting, but the evolution over time depends on the kinetic degradation parameters. Experimental scatter makes model testing difficult. Nevertheless, the model provides qualitative understanding of the influence of key variables. Copyright © 2013 Elsevier B.V. All rights reserved.

Comparison of Ultrasound-Assisted and Regular Leaching of Vanadium and Chromium from Roasted High Chromium Vanadium Slag

NASA Astrophysics Data System (ADS)

Wen, Jing; Jiang, Tao; Gao, Huiyang; Liu, Yajing; Zheng, Xiaole; Xue, Xiangxin

2018-02-01

Ultrasound-assisted leaching (UAL) was used for vanadium and chromium leaching from roasted material obtained by the calcification roasting of high-chromium-vanadium slag. UAL was compared with regular leaching. The effect of the leaching time and temperature, acid concentration, and liquid-solid ratio on the vanadium and chromium leaching behaviors was investigated. The UAL mechanism was determined from particle-size-distribution and microstructure analyses. UAL decreased the reaction time and leaching temperature significantly. Furthermore, 96.67% vanadium and less than 1% chromium were leached at 60°C for 60 min with 20% H2SO4 at a liquid-solid ratio of 8, which was higher than the maximum vanadium leaching rate of 90.89% obtained using regular leaching at 80°C for 120 min. Ultrasonic waves broke and dispersed the solid sample because of ultrasonic cavitation, which increased the contact area of the roasted sample and the leaching medium, the solid-liquid mass transfer, and the vanadium leaching rate.

Parametric study of rock pile thermal storage for solar heating and cooling phase 1

NASA Technical Reports Server (NTRS)

Saha, H.

1977-01-01

The test data and an analysis were presented, of heat transfer characteristics of a solar thermal energy storage bed utilizing water filled cans as the energy storage medium. An attempt was made to optimize can size, can arrangement, and bed flow rates by experimental and analytical means. Liquid filled cans, as storage media, utilize benefits of both solids like rocks, and liquids like water. It was found that this combination of solid and liquid media shows unique heat transfer and heat content characteristics and is well suited for use with solar air systems for space and hot water heating. An extensive parametric study was made of heat transfer characteristics of rocks, of other solids, and of solid containers filled with liquids.

Microgravity Boiling Enhancement Using Vibration-Based Fluidic Technologies

NASA Astrophysics Data System (ADS)

Smith, Marc K.; Glezer, Ari; Heffington, Samuel N.

2002-11-01

Thermal management is an important subsystem in many devices and technologies used in a microgravity environment. The increased power requirements of new Space technologies and missions mean that the capacity and efficiency of thermal management systems must be improved. The current work addresses this need through the investigation and development of a direct liquid immersion heat transfer cell for microgravity applications. The device is based on boiling heat transfer enhanced by two fluidic technologies developed at Georgia Tech. The first of these fluidic technologies, called vibration-induced bubble ejection, is shown in Fig. 1. Here, an air bubble in water is held against a vibrating diaphragm by buoyancy. The vibrations at 440 Hz induce violent oscillations of the air/water interface that can result in small bubbles being ejected from the larger air bubble (Fig. 1a) and, simultaneously, the collapse of the air/water interface against the solid surface (Fig. 1b). Both effects would be useful during a heat transfer process. Bubble ejection would force vapor bubbles back into the cooler liquid so that they can condense. Interfacial collapse would tend to keep the hot surface wet thereby increasing liquid evaporation and heat transfer to the bulk liquid. Figure 2 shows the effect of vibrating the solid surface at 7.6 kHz. Here, small-scale capillary waves appear on the surface of the bubble near the attachment point on the solid surface (the grainy region). The vibration produces a net force on the bubble that pushes it away from the solid surface. As a result, the bubble detaches from the solid and is propelled into the bulk liquid. This force works against buoyancy and so it would be even more effective in a microgravity environment. The benefit of the force in a boiling process would be to push vapor bubbles off the solid surface, thus helping to keep the solid surface wet and increasing the heat transfer. The second fluidic technology to be employed in this work is a synthetic jet, shown schematically in Fig. 3. The jet is produced using a small, sealed cavity with a sharp-edged orifice on one side and a vibrating diaphragm on the opposite side. The jet is formed when fluid is alternately sucked into and then expelled from the cavity by the motion of the diaphragm. This alternating motion means that there is no net mass addition to the system. Thus, there is no need for input piping or complex fluidic packaging.

On the role of heat and mass transfer into laser processability during selective laser melting AlSi12 alloy based on a randomly packed powder-bed

NASA Astrophysics Data System (ADS)

Wang, Lianfeng; Yan, Biao; Guo, Lijie; Gu, Dongdong

2018-04-01

A newly transient mesoscopic model with a randomly packed powder-bed has been proposed to investigate the heat and mass transfer and laser process quality between neighboring tracks during selective laser melting (SLM) AlSi12 alloy by finite volume method (FVM), considering the solid/liquid phase transition, variable temperature-dependent properties and interfacial force. The results apparently revealed that both the operating temperature and resultant cooling rate were obviously elevated by increasing the laser power. Accordingly, the resultant viscosity of liquid significantly reduced under a large laser power and was characterized with a large velocity, which was prone to result in a more intensive convection within pool. In this case, the sufficient heat and mass transfer occurred at the interface between the previously fabricated tracks and currently building track, revealing a strongly sufficient spreading between the neighboring tracks and a resultant high-quality surface without obvious porosity. By contrast, the surface quality of SLM-processed components with a relatively low laser power notably weakened due to the limited and insufficient heat and mass transfer at the interface of neighboring tracks. Furthermore, the experimental surface morphologies of the top surface were correspondingly acquired and were in full accordance to the calculated results via simulation.

Experimental investigations of interaction of an air-droplet-crystal flow with a solid body in the problem of a flyer icing

NASA Astrophysics Data System (ADS)

Kashevarov, Alexey V.; Miller, Alexey B.; Potapov, Yuriy F.; Stasenko, Albert L.; Zhbanov, Vladimir A.

2018-05-01

An experimental facility for modeling of icing processes in various conditions (supercooled droplets, ice crystals and mixed-phase) is described and experimental results are presented. Some methods of icing processes characterization with non-dimensional coefficients are suggested. Theoretical model of a liquid film dynamics, mass and heat transfer during its movement on the model surface is presented. The numerical calculations of liquid film freezing and run-back ice evolution on the surface are performed.

Methanol Steam Reforming Promoted by Molten Salt-Modified Platinum on Alumina Catalysts

PubMed Central

Kusche, Matthias; Agel, Friederike; Ní Bhriain, Nollaig; Kaftan, Andre; Laurin, Mathias; Libuda, Jörg; Wasserscheid, Peter

2014-01-01

We herein describe a straight forward procedure to increase the performance of platinum-on-alumina catalysts in methanol steam reforming by applying an alkali hydroxide coating according to the “solid catalyst with ionic liquid layer” (SCILL) approach. We demonstrate by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and temperature-programmed desorption (TPD) studies that potassium doping plays an important role in the catalyst activation. Moreover, the hygroscopic nature and the basicity of the salt modification contribute to the considerable enhancement in catalytic performance. During reaction, a partly liquid film of alkali hydroxides/carbonates forms on the catalyst/alumina surface, thus significantly enhancing the availability of water at the catalytically active sites. Too high catalyst pore fillings with salt introduce a considerable mass transfer barrier into the system as indicated by kinetic studies. Thus, the optimum interplay between beneficial catalyst modification and detrimental mass transfer effects had to be identified and was found on the applied platinum-on-alumina catalyst at KOH loadings around 7.5 mass %. PMID:25124120

Effect of Schmidt number on mass transfer across a sheared gas-liquid interface in a wind-driven turbulence.

PubMed

Takagaki, Naohisa; Kurose, Ryoichi; Kimura, Atsushi; Komori, Satoru

2016-11-14

The mass transfer across a sheared gas-liquid interface strongly depends on the Schmidt number. Here we investigate the relationship between mass transfer coefficient on the liquid side, k L , and Schmidt number, Sc, in the wide range of 0.7 ≤ Sc ≤ 1000. We apply a three-dimensional semi direct numerical simulation (SEMI-DNS), in which the mass transfer is solved based on an approximated deconvolution model (ADM) scheme, to wind-driven turbulence with mass transfer across a sheared wind-driven wavy gas-liquid interface. In order to capture the deforming gas-liquid interface, an arbitrary Lagrangian-Eulerian (ALE) method is employed. Our results show that similar to the case for flat gas-liquid interfaces, k L for the wind-driven wavy gas-liquid interface is generally proportional to Sc -0.5 , and can be roughly estimated by the surface divergence model. This trend is endorsed by the fact that the mass transfer across the gas-liquid interface is controlled mainly by streamwise vortices on the liquid side even for the wind-driven turbulence under the conditions of low wind velocities without wave breaking.

Effect of Schmidt number on mass transfer across a sheared gas-liquid interface in a wind-driven turbulence

PubMed Central

Takagaki, Naohisa; Kurose, Ryoichi; Kimura, Atsushi; Komori, Satoru

2016-01-01

The mass transfer across a sheared gas-liquid interface strongly depends on the Schmidt number. Here we investigate the relationship between mass transfer coefficient on the liquid side, kL, and Schmidt number, Sc, in the wide range of 0.7 ≤ Sc ≤ 1000. We apply a three-dimensional semi direct numerical simulation (SEMI-DNS), in which the mass transfer is solved based on an approximated deconvolution model (ADM) scheme, to wind-driven turbulence with mass transfer across a sheared wind-driven wavy gas-liquid interface. In order to capture the deforming gas-liquid interface, an arbitrary Lagrangian-Eulerian (ALE) method is employed. Our results show that similar to the case for flat gas-liquid interfaces, kL for the wind-driven wavy gas-liquid interface is generally proportional to Sc−0.5, and can be roughly estimated by the surface divergence model. This trend is endorsed by the fact that the mass transfer across the gas-liquid interface is controlled mainly by streamwise vortices on the liquid side even for the wind-driven turbulence under the conditions of low wind velocities without wave breaking. PMID:27841325

How changing the particle structure can speed up protein mass transfer kinetics in liquid chromatography.

PubMed

Gritti, Fabrice; Horvath, Krisztian; Guiochon, Georges

2012-11-09

The mass transfer kinetics of a few compounds (uracil, 112 Da), insulin (5.5 kDa), lysozyme (13.4 kDa), and bovine serum albumin (BSA, 67 kDa) in columns packed with several types of spherical particles was investigated under non-retained conditions, in order to eliminate the poorly known contribution of surface diffusion to overall sample diffusivity across the porous particles in RPLC. Diffusivity across particles is then minimum. Based on the porosity of the particles accessible to analytes, it was accurately estimated from the elution times, the internal obstruction factor (using Pismen correlation), and the hindrance diffusion factor (using Renkin correlation). The columns used were packed with fully porous particles 2.5 μm Luna-C(18) 100 Å, core-shell particles 2.6 μm Kinetex-C(18) 100 Å, 3.6 μm Aeris Widepore-C(18) 200 Å, and prototype 2.7 μm core-shell particles (made of two concentric porous shells with 100 and 300 Å average pore size, respectively), and with 3.3 μm non-porous silica particles. The results demonstrate that the porous particle structure and the solid-liquid mass transfer resistance have practically no effect on the column efficiency for small molecules. For them, the column performance depends principally on eddy dispersion (packing homogeneity), to a lesser degree on longitudinal diffusion (effective sample diffusivity along the packed bed), and only slightly on the solid-liquid mass transfer resistance (sample diffusivity across the particle). In contrast, for proteins, this third HETP contribution, hence the porous particle structure, together with eddy dispersion govern the kinetic performance of columns. Mass transfer kinetics of proteins was observed to be fastest for columns packed with core-shell particles having either a large core-to-particle ratio or having a second, external, shell made of a thin porous layer with large mesopores (200-300 Å) and a high porosity (~/=0.5-0.7). The structure of this external shell seems to speed up the penetration of proteins into the particles. A stochastic model of the penetration of bulky proteins driven by a concentration gradient across an infinitely thin membrane of known porosity and pore size is suggested to explain this mechanism. Yet, under retained conditions, surface diffusion speeds up the mass transfer into the mesopores and levels the kinetic performance of particles built with either one or two porous shells. Copyright © 2012 Elsevier B.V. All rights reserved.

Numerical Analysis of Coolant Flow and Heat Transfer in ITER Diagnostic First Wall

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khodak, A.; Loesser, G.; Zhai, Y.

2015-07-24

We performed numerical simulations of the ITER Diagnostic First Wall (DFW) using ANSYS workbench. During operation DFW will include solid main body as well as liquid coolant. Thus thermal and hydraulic analysis of the DFW was performed using conjugated heat transfer approach, in which heat transfer was resolved in both solid and liquid parts, and simultaneously fluid dynamics analysis was performed only in the liquid part. This approach includes interface between solid and liquid part of the systemAnalysis was performed using ANSYS CFX software. CFX software allows solution of heat transfer equations in solid and liquid part, and solution ofmore » the flow equations in the liquid part. Coolant flow in the DFW was assumed turbulent and was resolved using Reynolds averaged Navier-Stokes equations with Shear Stress Transport turbulence model. Meshing was performed using CFX method available within ANSYS. The data cloud for thermal loading consisting of volumetric heating and surface heating was imported into CFX Volumetric heating source was generated using Attila software. Surface heating was obtained using radiation heat transfer analysis. Our results allowed us to identify areas of excessive heating. Proposals for cooling channel relocation were made. Additional suggestions were made to improve hydraulic performance of the cooling system.« less

Liquid droplet radiator performance studies

NASA Astrophysics Data System (ADS)

Mattick, A. T.; Hertzberg, A.

By making use of droplets rather than solid surfaces to radiate waste heat in space, the liquid droplet radiator (LDR) achieves a radiating area/mass much larger than that of conventional radiators which use fins or heat pipes. The lightweight potential of the LDR is shown to be limited primarily by the radiative properties of the droplets. The requirement that the LDR heat transfer fluid have a very low vapor pressure limits the choice of fluids to relatively few—several liquid metals and Dow 705 silicone fluid are the only suitable candidates so far identified. An experimental determination of the emittance of submillimeter droplets of Dow 705 fluid indicates than an LDR using this fluid at temperatures of 275-335 K would be ⋍ 10 times lighter than the lightest solid surface radiators. Although several liquid metals appear to offer excellent performance in LDR applications at temperatures between 200 K and 975 K, experimental determination of liquid metal emissivities is needed for a conclusive assessment.

Liquid droplet radiator performance studies

NASA Technical Reports Server (NTRS)

Mattick, A. T.; Hertzberg, A.

1984-01-01

By making use of droplets rather than solid surfaces to radiate waste heat in space, the liquid-droplet radiator (LDR) achieves a radiating area/mass much larger than that of conventional radiators which use fins or heat pipes. The light-weight potential of the LDR is shown to be limited primarily by the radiative properties of the droplets. The requirement that the LDR heat-transfer fluid have a very low vapor pressure limits the choice of fluids to relatively few several liquid metals and a silicone fluid are the only suitable candidates so far identified. An experimental determination of the emittance of submillimeter droplets of the silicon fluid indicates that an LDR using this fluid at temperatures of 275-335 K would be about 10 times lighter than the lightest solid-surface radiators. Although several liquid metals appear to offer excellent performance in LDR applications at temperatures between 200 and 975 K, experimental determination of liquid-metal emissivities is needed for a conclusive assessment.

Liquid droplet radiator performance studies

NASA Astrophysics Data System (ADS)

Mattick, A. T.; Hertzberg, A.

1984-10-01

By making use of droplets rather than solid surfaces to radiate waste heat in space, the liquid-droplet radiator (LDR) achieves a radiating area/mass much larger than that of conventional radiators which use fins or heat pipes. The light-weight potential of the LDR is shown to be limited primarily by the radiative properties of the droplets. The requirement that the LDR heat-transfer fluid have a very low vapor pressure limits the choice of fluids to relatively few several liquid metals and a silicone fluid are the only suitable candidates so far identified. An experimental determination of the emittance of submillimeter droplets of the silicon fluid indicates that an LDR using this fluid at temperatures of 275-335 K would be about 10 times lighter than the lightest solid-surface radiators. Although several liquid metals appear to offer excellent performance in LDR applications at temperatures between 200 and 975 K, experimental determination of liquid-metal emissivities is needed for a conclusive assessment.

Simulation of Hanford Tank 241-C-106 Waste Release into Tank 241-Y-102

DOE Office of Scientific and Technical Information (OSTI.GOV)

KP Recknagle; Y Onishi

Waste stored in Hdord single-shell Tank 241-C-106 will be sluiced with a supernatant liquid from doubIe-shell Tank 241 -AY- 102 (AY-1 02) at the U.S. Department of Energy's Har@ord Site in Eastern Washington. The resulting slurry, containing up to 30 wtYo solids, will then be transferred to Tank AY-102. During the sluicing process, it is important to know the mass of the solids being transferred into AY- 102. One of the primary instruments used to measure solids transfer is an E+ densitometer located near the periphery of the tank at riser 15S. This study was undert.dcen to assess how wellmore » a densitometer measurement could represent the total mass of soiids transferred if a uniform lateral distribution was assumed. The study evaluated the C-1 06 slurry mixing and accumulation in Tank AY- 102 for the following five cases: Case 1: 3 wt'%0 slurry in 6.4-m AY-102 waste Case 2: 3 w-t% slurry in 4.3-m AY-102 waste Case 3: 30 wtYo slurry in 6.4-m AY-102 waste Case 4: 30 wt% slurry in 4.3-m AY-102 waste Case 5: 30 wt% slurry in 5. O-m AY-102 waste. The tirne-dependent, three-dimensional, TEMPEST computer code was used to simulate solid deposition and accumulation during the injection of the C-106 slurry into AY-102 through four injection nozzles. The TEMPEST computer code was applied previously to other Hanford tanks, AP-102, SY-102, AZ-101, SY-101, AY-102, and C-106, to model tank waste mixing with rotating pump jets, gas rollover events, waste transfer from one tank to another, and pump-out retrieval of the sluiced waste. The model results indicate that the solid depth accumulated at the densitometer is within 5% of the average depth accumulation. Thus the reading of the densitometer is expected to represent the total mass of the transferred solids reasonably well.« less

Analytical solutions for combined close-contact and natural convection melting in horizontal cylindrical heat storage capsule

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saitoh, T.S.; Hoshi, A.

1998-07-01

Melting and solidification of a phase change material (PCM) in a capsule is of practical importance in latent heat thermal energy storage (LHTES) systems which are considered to be very promising to reduce a peak demand of electricity in the summer season and carbon dioxide (CO{sub 2}) emissions. Two melting modes are involved in melting of capsules. One is close-contact melting between the solid bulk and the capsule wall, and another is natural convection melting in the liquid region. Close-contact melting processes for a single enclosure have been solved using several numerical methods (e.g., Saitoh and Kato (1994)). In additionmore » close-contact melting heat transfer characteristics including melt flow in the liquid film under inner wall temperature distribution were analyzed and simple approximate equations were already presented by Saitoh and Hoshi (1997). The effects of Stefan number and variable temperature profile etc. were clarified in detail. And the melting velocity of the solid bulk under various conditions was also studied theoretically. In addition the effects of variable inner wall temperature on molten mass fraction were investigated. The present paper reports analytical solutions for combined close-contact and natural convection melting in horizontal cylindrical capsule. Moreover, natural convection melting in the liquid region were analyzed in this report. The upper interface shape of the solid bulk is approximated by a circular arc throughout the melting process. For the sake of verification, close-contact melting heat-transfer characteristics including natural convection in the liquid region were studied experimentally. Apparent shift of upper solid-liquid interface is good agreement with the experiment. The present simple approximate solutions will be useful to facilitate designing of the practical capsule bed LHTES systems.« less

Kinetic modelling of a diesel-polluted clayey soil bioremediation process.

PubMed

Fernández, Engracia Lacasa; Merlo, Elena Moliterni; Mayor, Lourdes Rodríguez; Camacho, José Villaseñor

2016-07-01

A mathematical model is proposed to describe a diesel-polluted clayey soil bioremediation process. The reaction system under study was considered a completely mixed closed batch reactor, which initially contacted a soil matrix polluted with diesel hydrocarbons, an aqueous liquid-specific culture medium and a microbial inoculation. The model coupled the mass transfer phenomena and the distribution of hydrocarbons among four phases (solid, S; water, A; non-aqueous liquid, NAPL; and air, V) with Monod kinetics. In the first step, the model simulating abiotic conditions was used to estimate only the mass transfer coefficients. In the second step, the model including both mass transfer and biodegradation phenomena was used to estimate the biological kinetic and stoichiometric parameters. In both situations, the model predictions were validated with experimental data that corresponded to previous research by the same authors. A correct fit between the model predictions and the experimental data was observed because the modelling curves captured the major trends for the diesel distribution in each phase. The model parameters were compared to different previously reported values found in the literature. Pearson correlation coefficients were used to show the reproducibility level of the model. Copyright © 2016. Published by Elsevier B.V.

Three-dimensional three-phase model for simulation of hydrodynamics, oxygen mass transfer, carbon oxidation, nitrification and denitrification in an oxidation ditch.

PubMed

Lei, Li; Ni, Jinren

2014-04-15

A three-dimensional three-phase fluid model, supplemented by laboratory data, was developed to simulate the hydrodynamics, oxygen mass transfer, carbon oxidation, nitrification and denitrification processes in an oxidation ditch. The model provided detailed phase information on the liquid flow field, gas hold-up distribution and sludge sedimentation. The three-phase model described water-gas, water-sludge and gas-sludge interactions. Activated sludge was taken to be in a pseudo-solid phase, comprising an initially separated solid phase that was transported and later underwent biological reactions with the surrounding liquidmedia. Floc parameters were modified to improve the sludge viscosity, sludge density, oxygen mass transfer rate, and carbon substrate uptake due to adsorption onto the activated sludge. The validation test results were in very satisfactory agreement with laboratory data on the behavior of activated sludge in an oxidation ditch. By coupling species transport and biological process models, reasonable predictions are made of: (1) the biochemical kinetics of dissolved oxygen, chemical oxygen demand (COD) and nitrogen variation, and (2) the physical kinematics of sludge sedimentation. Copyright © 2014 Elsevier Ltd. All rights reserved.

Ionic-liquid-based dispersive liquid-liquid microextraction combined with magnetic solid-phase extraction for the determination of aflatoxins B1 , B2 , G1 , and G2 in animal feeds by high-performance liquid chromatography with fluorescence detection.

PubMed

Zhao, Jiao; Zhu, Yan; Jiao, Yang; Ning, Jinyan; Yang, Yaling

2016-10-01

A novel two-step extraction technique combining ionic-liquid-based dispersive liquid-liquid microextraction with magnetic solid-phase extraction was developed for the preconcentration and separation of aflatoxins in animal feedstuffs before high-performance liquid chromatography coupled with fluorescence detection. In this work, ionic liquid 1-octyl-3-methylimidazolium hexafluorophosphate was used as the extractant in dispersive liquid-liquid microextraction, and hydrophobic pelargonic acid modified Fe 3 O 4 magnetic nanoparticles as an efficient adsorbent were applied to retrieve the aflatoxins-containing ionic liquid. Notably, the target of magnetic nanoparticles was the ionic liquid rather than the aflatoxins. Because of the rapid mass transfer associated with the dispersive liquid-liquid microextraction and magnetic solid phase steps, fast extraction could be achieved. The main parameters affecting the extraction recoveries of aflatoxins were investigated and optimized. Under the optimum conditions, vortexing at 2500 rpm for 1 min in the dispersive liquid-liquid microextraction and magnetic solid-phase extraction and then desorption by sonication for 2 min with acetonitrile as eluent. The recoveries were 90.3-103.7% with relative standard deviations of 3.2-6.4%. Good linearity was observed with correlation coefficients ranged from 0.9986 to 0.9995. The detection limits were 0.632, 0.087, 0.422 and 0.146 ng/mL for aflatoxins B 1 , B2, G1, and G2, respectively. The results were also compared with the pretreatment method carried out by conventional immunoaffinity columns. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mathematical modeling heat and mass transfer processes in porous media

NASA Astrophysics Data System (ADS)

Akhmed-Zaki, Darkhan

2013-11-01

On late development stages of oil-fields appears a complex problem of oil-recovery reduction. One of solution approaches is injecting of surfactant together with water in the form of active impurities into the productive layer - for decreasing oil viscosity and capillary forces between ``oil-water'' phases system. In fluids flow the surfactant can be in three states: dissolved in water, dissolved in oil and adsorbed on pore channels' walls. The surfactant's invasion into the reservoir is tracked by its diffusion with reservoir liquid and mass-exchange with two phase (liquid and solid) components of porous structure. Additionally, in this case heat exchange between fluids (injected, residual) and framework of porous medium has practical importance for evaluating of temperature influences on enhancing oil recovery. Now, the problem of designing an adequate mathematical model for describing a simultaneous flowing heat and mass transfer processes in anisotropic heterogeneous porous medium -surfactant injection during at various temperature regimes has not been fully researched. In this work is presents a 2D mathematical model of surfactant injections into the oil reservoir. Description of heat- and mass transfer processes in a porous media is done through differential and kinetic equations. For designing a computational algorithm is used modify version of IMPES method. The sequential and parallel computational algorithms are developed using an adaptive curvilinear meshes which into account heterogeneous porous structures. In this case we can evaluate the boundaries of our process flows - fronts (``invasion'', ``heat'' and ``mass'' transfers), according to the pressure, temperature, and concentration gradient changes.

Charge transfer kinetics at the solid-solid interface in porous electrodes

NASA Astrophysics Data System (ADS)

Bai, Peng; Bazant, Martin Z.

2014-04-01

Interfacial charge transfer is widely assumed to obey the Butler-Volmer kinetics. For certain liquid-solid interfaces, the Marcus-Hush-Chidsey theory is more accurate and predictive, but it has not been applied to porous electrodes. Here we report a simple method to extract the charge transfer rates in carbon-coated LiFePO4 porous electrodes from chronoamperometry experiments, obtaining curved Tafel plots that contradict the Butler-Volmer equation but fit the Marcus-Hush-Chidsey prediction over a range of temperatures. The fitted reorganization energy matches the Born solvation energy for electron transfer from carbon to the iron redox site. The kinetics are thus limited by electron transfer at the solid-solid (carbon-LixFePO4) interface rather than by ion transfer at the liquid-solid interface, as previously assumed. The proposed experimental method generalizes Chidsey’s method for phase-transforming particles and porous electrodes, and the results show the need to incorporate Marcus kinetics in modelling batteries and other electrochemical systems.

Quantification of bulk solution limits for liquid and interfacial transport in nanoconfinements.

PubMed

Kelly, Shaina; Balhoff, Matthew T; Torres-Verdín, Carlos

2015-02-24

Liquid imbibition, the capillary-pressure-driven flow of a liquid into a gas, provides a mechanism for studying the effects of solid-liquid and solid-liquid-gas interfaces on nanoscale transport. Deviations from the classic Washburn equation for imbibition are generally observed for nanoscale imbibition, but the identification of the origin of these irregularities in terms of transport variables varies greatly among investigators. We present an experimental method and corresponding image and data analysis scheme that enable the determination of independent effective values of nanoscale capillary pressure, liquid viscosity, and interfacial gas partitioning coefficients, all critical transport variables, from imbibition within nanochannels. Experiments documented herein are performed within two-dimensional siliceous nanochannels of varying size and as small as 30 nm × 60 nm in cross section. The wetting fluid used is the organic solvent isopropanol and the nonwetting fluid is air, but investigations are not limited to these fluids. Optical data of dynamic flow are rare in geometries that are nanoscale in two dimensions due to the limited resolution of optical microscopy. We are able to capture tracer-free liquid imbibition with reflected differential interference contrast microscopy. Results with isopropanol show a significant departure from bulk transport values in the nanochannels: reduced capillary pressures, increased liquid viscosity, and nonconstant interfacial mass-transfer coefficients. The findings equate to the nucleation of structured, quasi-crystalline boundary layers consistently ∼10-25 nm in extent. This length is far thicker than the boundary layer range prescribed by long-range intermolecular force interactions. Slower but linear imbibition in some experimental cases suggests that structured boundary layers may inhibit viscous drag at confinement walls for critical nanochannel dimensions. Probing the effects of nanoconfinement on the definitions of capillary pressure, viscosity, and interfacial mass transfer is critical in determining and improving the functionality and fluid transport efficacy of geological, biological, and synthetic nanoporous media and materials.

An investigation on near wall transport characteristics in an adiabatic upward gas-liquid two-phase slug flow

NASA Astrophysics Data System (ADS)

Zheng, Donghong; Che, Defu

2007-08-01

The near-wall transport characteristics, inclusive of mass transfer coefficient and wall shear stress, which have a great effect on gas-liquid two-phase flow induced internal corrosion of low alloy pipelines in vertical upward oil and gas mixing transport, have been both mechanistically and experimentally investigated in this paper. Based on the analyses on the hydrodynamic characteristics of an upward slug unit, the mass transfer in the near wall can be divided into four zones, Taylor bubble nose zone, falling liquid film zone, Taylor bubble wake zone and the remaining liquid slug zone; the wall shear stress can be divided into two zones, the positive wall shear stress zone associated with the falling liquid film and the negative wall shear stress zone associated with the liquid slug. Based on the conventional mass transfer and wall shear stress characteristics formulas of single phase liquid full-pipe turbulent flow, corrected normalized mass transfer coefficient formula and wall shear stress formula are proposed. The calculated results are in good agreement with the experimental data. The shear stress and the mass transfer coefficient in the near wall zone are increased with the increase of superficial gas velocity and decreased with the increase of superficial liquid velocity. The mass transfer coefficients in the falling liquid film zone and the wake zone of leading Taylor bubble are lager than those in the Taylor bubble nose zone and the remaining liquid slug zone, and the wall shear stress associated falling liquid film is larger than that associated the liquid slug. The mass transfer coefficient is within 10-3 m/s, and the wall shear stress below 103 Pa. It can be concluded that the alternate wall shear stress due to upward gas-liquid slug flow is considered to be the major cause of the corrosion production film fatigue cracking.

The quantitative impact of the mesopore size on the mass transfer mechanism of the new 1.9μm fully porous Titan-C18 particles. I: analysis of small molecules.

PubMed

Gritti, Fabrice; Guiochon, Georges

2015-03-06

Previous data have shown that could deliver a minimum reduced plate height as small as 1.7. Additionally, the reduction of the mesopore size after C18 derivatization and the subsequent restriction for sample diffusivity across the Titan-C18 particles were found responsible for the unusually small value of the experimental optimum reduced velocity (5 versus 10 for conventional particles) and for the large values of the average reduced solid-liquid mass transfer resistance coefficients (0.032 versus 0.016) measured for a series of seven n-alkanophenones. The improvements in column efficiency made by increasing the average mesopore size of the Titan silica from 80 to 120Å are investigated from a quantitative viewpoint based on the accurate measurements of the reduced coefficients (longitudinal diffusion, trans-particle mass transfer resistance, and eddy diffusion) and of the intra-particle diffusivity, pore, and surface diffusion for the same series of n-alkanophenone compounds. The experimental results reveal an increase (from 0% to 30%) of the longitudinal diffusion coefficients for the same sample concentration distribution (from 0.25 to 4) between the particle volume and the external volume of the column, a 40% increase of the intra-particle diffusivity for the same sample distribution (from 1 to 7) between the particle skeleton volume and the bulk phase, and a 15-30% decrease of the solid-liquid mass transfer coefficient for the n-alkanophenone compounds. Pore and surface diffusion are increased by 60% and 20%, respectively. The eddy dispersion term and the maximum column efficiency (295000plates/m) remain virtually unchanged. The rate of increase of the total plate height with increasing the chromatographic speed is reduced by 20% and it is mostly controlled (75% and 70% for 80 and 120Å pore size) by the flow rate dependence of the eddy dispersion term. Copyright © 2015 Elsevier B.V. All rights reserved.

Effect of operating temperature on styrene mass transfer characteristics in a biotrickling filter.

PubMed

Parnian, Parham; Zamir, Seyed Morteza; Shojaosadati, Seyed Abbas

2017-05-01

To study the effect of operating temperature on styrene mass transfer from gas to liquid phase in biotrickling filters (BTFs), overall mass transfer coefficient (K L a) was calculated through fitting test data to a general mass balance model under abiotic conditions. Styrene was used as the volatile organic compound and the BTF was packed with a mixture of pall rings and pumice. Operating temperature was set at 30°C and 50°C for mesophilic and thermophilic conditions, respectively. K L a values increased from 54 to 70 h -1 at 30°C and from 60 to 90 h -1 at 50°C, respectively, depending on the countercurrent gas to liquid flow ratio that varied in the range of 7.5-32. Evaluation of styrene mass transfer capacity (MTC) showed that liquid-phase mass transfer resistance decreased as the flow ratio increased at constant temperature. MTC also decreased with an increase in operating temperature. Both gas-liquid partition coefficient and K L a increased with increasing temperature; however the effect on gas-liquid partition coefficient was more significant and served to increase mass transfer limitations. Thermophilic biofiltration on the one hand increases mass transfer limitations, but on the other hand may enhance the biodegradation rate in favor of enhancing BTFs' performance.

Effect of acoustic streaming on the mass transfer from a sublimating sphere

NASA Astrophysics Data System (ADS)

Kawahara, N.; Yarin, A. L.; Brenn, G.; Kastner, O.; Durst, F.

2000-04-01

The effect of the acoustic streaming on the mass transfer from the surface of a sphere positioned in an ultrasonic acoustic levitator is studied both experimentally and theoretically. Acoustic levitation using standing ultrasonic waves is an experimental tool for studying the heat and mass transfer from small solid or liquid samples, because it allows an almost steady positioning of a sample at a fixed location in space. However, the levitator introduces some difficulties. One of the main problems with acoustic levitation is that an acoustic streaming is induced near the sample surface, which affects the heat and mass transfer rates, as characterized by increased Nusselt and Sherwood numbers. The transfer rates are not uniform along the sample surface, and the aim of the present study is to quantify the spatial Sherwood number distribution over the surface of a sphere. The experiments are based on the measurement of the surface shape of a sphere layered with a solid substance as a function of time using a charge-coupled device (CCD) camera with backlighting. The sphere used in this research is a glass sphere layered with a volatile solid substance (naphthalene or camphor). The local mass transfer from the surface both with and without an ultrasonic acoustic field is investigated in order to evaluate the effect of the acoustic streaming. The experimental results are compared with predictions following from the theory outlined [A. L. Yarin, M. Pfaffenlehner, and C. Tropea, J. Fluid Mech. 356, 65 (1998); A. L. Yarin, G. Brenn, O. Kastner, D. Rensink, and C. Tropea, ibid. 399, 151 (1999)] which describes the acoustic field and the resulting acoustic streaming, and the mass transfer at the surface of particles and droplets located in an acoustic levitator. The results are also compared with the experimental data and with the theoretical predictions of Burdukov and Nakoryakov [J. Appl. Mech. Tech. Phys. 6, 51 (1965)], which are valid only in the case of spherical particles much smaller than the sound wavelength. Good agreement between experiment and the theory of Yarin et al. is demonstrated. The time-averaged heat and mass transfer rates over a sphere surface are greatest at the sphere's equator and least at its poles in the experiment as predicted by the theory (the ultrasonic standing wave spans the vertical axis passing through the poles). The measured distribution of the mass transfer rate over the sphere surface also agrees with the theoretical predictions, which shows that in strong acoustic fields sublimation (or evaporation) results from the acoustic streaming.

Methanol steam reforming promoted by molten salt-modified platinum on alumina catalysts.

PubMed

Kusche, Matthias; Agel, Friederike; Ní Bhriain, Nollaig; Kaftan, Andre; Laurin, Mathias; Libuda, Jörg; Wasserscheid, Peter

2014-09-01

We herein describe a straight forward procedure to increase the performance of platinum-on-alumina catalysts in methanol steam reforming by applying an alkali hydroxide coating according to the "solid catalyst with ionic liquid layer" (SCILL) approach. We demonstrate by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and temperature-programmed desorption (TPD) studies that potassium doping plays an important role in the catalyst activation. Moreover, the hygroscopic nature and the basicity of the salt modification contribute to the considerable enhancement in catalytic performance. During reaction, a partly liquid film of alkali hydroxides/carbonates forms on the catalyst/alumina surface, thus significantly enhancing the availability of water at the catalytically active sites. Too high catalyst pore fillings with salt introduce a considerable mass transfer barrier into the system as indicated by kinetic studies. Thus, the optimum interplay between beneficial catalyst modification and detrimental mass transfer effects had to be identified and was found on the applied platinum-on-alumina catalyst at KOH loadings around 7.5 mass%. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Thermal Transport at Solid-Liquid Interfaces: High Pressure Facilitates Heat Flow through Nonlocal Liquid Structuring.

PubMed

Han, Haoxue; Mérabia, Samy; Müller-Plathe, Florian

2017-05-04

The integration of three-dimensional microelectronics is hampered by overheating issues inherent to state-of-the-art integrated circuits. Fundamental understanding of heat transfer across soft-solid interfaces is important for developing efficient heat dissipation capabilities. At the microscopic scale, the formation of a dense liquid layer at the solid-liquid interface decreases the interfacial heat resistance. We show through molecular dynamics simulations of n-perfluorohexane on a generic wettable surface that enhancement of the liquid structure beyond a single adsorbed layer drastically enhances interfacial heat conductance. Pressure is used to control the extent of the liquid layer structure. The interfacial thermal conductance increases with pressure values up to 16.2 MPa at room temperature. Furthermore, it is shown that liquid structuring enhances the heat-transfer rate of high-energy lattice waves by broadening the transmission peaks in the heat flux spectrum. Our results show that pressure is an important external parameter that may be used to control interfacial heat conductance at solid-soft interfaces.

A new approach to determine the density of liquids and solids without measuring mass and volume: introducing the solidensimeter

NASA Astrophysics Data System (ADS)

Kiriktaş, Halit; Şahin, Mehmet; Eslek, Sinan; Kiriktaş, İrem

2018-05-01

This study aims to design a mechanism with which the density of any solid or liquid can be determined without measuring its mass and volume in order to help students comprehend the concept of density more easily. The solidensimeter comprises of two scaled and nested glass containers (graduated cylinder or beaker) and sufficient water. In this method, the density measurement was made using the Archimedes’ principle stating that an object fully submerged in a liquid displaces the same amount of liquid as its volume, while an object partially submerged or floating displaces the same amount of liquid as its mass. Using this method, the density of any solids or liquids can be determined using a simple mathematical ratio. At the end of the process a mechanism that helps students to comprehend the density topic more easily was designed. The system is easy-to-design, uses low-cost equipment and enables one to determine the density of any solid or liquid without measuring its mass and volume.

Identifying and overcoming the effect of mass transfer limitation on decreased yield in enzymatic hydrolysis of lignocellulose at high solid concentrations.

PubMed

Du, Jian; Cao, Yuan; Liu, Guodong; Zhao, Jian; Li, Xuezhi; Qu, Yinbo

2017-04-01

Cellulose conversion decreases significantly with increasing solid concentrations during enzymatic hydrolysis of insoluble lignocellulosic materials. Here, mass transfer limitation was identified as a significant determining factor of this decrease by studying the hydrolysis of delignified corncob residue in shake flask, the most used reaction vessel in bench scale. Two mass transfer efficiency-related factors, mixing speed and flask filling, were shown to correlate closely with cellulose conversion at solid loadings higher than 15% DM. The role of substrate characteristics in mass transfer performance was also significant, which was revealed by the saccharification of two corn stover substrates with different pretreatment methods at the same solid loading. Several approaches including premix, fed-batch operation, and particularly the use of horizontal rotating reactor were shown to be valid in facilitating cellulose conversion via improving mass transfer efficiency at solid concentrations higher than 15% DM. Copyright © 2017 Elsevier Ltd. All rights reserved.

ELECTRON TRANSFER MECHANISM AT THE SOLID-LIQUID INTERFACE OF PHYLLOSILICATES

EPA Science Inventory

Interfacial electron transfer processes on clay minerals have significant impact in natural environments and geochemical systems. Nitrobenzene was used as molecular probes to study the electron transfer mechanism at the solid-water interfaces of Fe-containing phyllosicates. For...

Effect of the Thermocouple on Measuring the Temperature Discontinuity at a Liquid-Vapor Interface.

PubMed

Kazemi, Mohammad Amin; Nobes, David S; Elliott, Janet A W

2017-07-18

The coupled heat and mass transfer that occurs in evaporation is of interest in a large number of fields such as evaporative cooling, distillation, drying, coating, printing, crystallization, welding, atmospheric processes, and pool fires. The temperature jump that occurs at an evaporating interface is of central importance to understanding this complex process. Over the past three decades, thermocouples have been widely used to measure the interfacial temperature jumps at a liquid-vapor interface during evaporation. However, the reliability of these measurements has not been investigated so far. In this study, a numerical simulation of a thermocouple when it measures the interfacial temperatures at a liquid-vapor interface is conducted to understand the possible effects of the thermocouple on the measured temperature and features in the temperature profile. The differential equations of heat transfer in the solid and fluids as well as the momentum transfer in the fluids are coupled together and solved numerically subject to appropriate boundary conditions between the solid and fluids. The results of the numerical simulation showed that while thermocouples can measure the interfacial temperatures in the liquid correctly, they fail to read the actual interfacial temperatures in the vapor. As the results of our numerical study suggest, the temperature jumps at a liquid-vapor interface measured experimentally by using a thermocouple are larger than what really exists at the interface. For a typical experimental study of evaporation of water at low pressure, it was found that the temperature jumps measured by a thermocouple are overestimated by almost 50%. However, the revised temperature jumps are still in agreement with the statistical rate theory of interfacial transport. As well as addressing the specific application of the liquid-vapor temperature jump, this paper provides significant insight into the role that heat transfer plays in the operation of thermocouples in general.

Heat and Mass Transfer of Ammonia Gas Absorption into Falling Liquid Film on a Horizontal Tube

NASA Astrophysics Data System (ADS)

Inoue, Norihiro; Yabuuchi, Hironori; Goto, Masao; Koyama, Shigeru

Heat and mass transfer coefficients during ammonia gas absorption into a falling liquid film formed by distilled water on a horizontal tube were obtained experimentally. The test absorber consists of 200 mm i.d., 600 mm long stainless steel shell, a 1 7.3 mm o.d., 14.9 mm i.d. stainless steel test tube with 600 mm working length mounted along the axis of shell, and a 12.7 mm o.d. pipe manifold of supplying the absorbent. In this paper, it was clear that heat and mass transfer coefficient could be enhanced by increasing the flow rate of absorbent and temperature difference between inlet absorbent and ammonia gas, also heat driven by the temperature difference have an effect on heat transfer of the fa1ling liquid film and mass transfer of vapor side. And the new correlation of heat transfer in dimensionless form was proposed by the temperature difference which was considered heat driven of vapor and liquid film side using a interface temperature of vapor and liquid phase. The new correlations of mass transfer on a interface of vapor and liquid phase in dimensionless form were proposed by using effect factors could be suppose from absorption phenomena.

Quantitative ionspray liquid chromatographic/tandem mass spectrometric determination of reserpine in equine plasma.

PubMed

Anderson, M A; Wachs, T; Henion, J D

1997-02-01

A method based on ionspray liquid chromatography/tandem mass spectrometry (LC/MS/MS) was developed for the determination of reserpine in equine plasma. A comparison was made of the isolation of reserpine from plasma by liquid-liquid extraction and by solid-phase extraction. A structural analog, rescinnamine, was used as the internal standard. The reconstituted extracts were analyzed by ionspray LC/MS/MS in the selected reaction monitoring (SRM) mode. The calibration graph for reserpine extracted from equine plasma obtained using liquid-liquid extraction was linear from 10 to 5000 pg ml-1 and that using solid-phase extraction from 100 to 5000 pg ml-1. The lower level of quantitation (LLQ) using liquid-liquid and solid-phase extraction was 50 and 200 pg ml-1, respectively. The lower level of detection for reserpine by LC/MS/MS was 10 pg ml-1. The intra-assay accuracy did not exceed 13% for liquid-liquid and 12% for solid-phase extraction. The recoveries for the LLQ were 68% for liquid-liquid and 58% for solid-phase extraction.

Snap evaporation of droplets on smooth topographies.

PubMed

Wells, Gary G; Ruiz-Gutiérrez, Élfego; Le Lirzin, Youen; Nourry, Anthony; Orme, Bethany V; Pradas, Marc; Ledesma-Aguilar, Rodrigo

2018-04-11

Droplet evaporation on solid surfaces is important in many applications including printing, micro-patterning and cooling. While seemingly simple, the configuration of evaporating droplets on solids is difficult to predict and control. This is because evaporation typically proceeds as a "stick-slip" sequence-a combination of pinning and de-pinning events dominated by static friction or "pinning", caused by microscopic surface roughness. Here we show how smooth, pinning-free, solid surfaces of non-planar topography promote a different process called snap evaporation. During snap evaporation a droplet follows a reproducible sequence of configurations, consisting of a quasi-static phase-change controlled by mass diffusion interrupted by out-of-equilibrium snaps. Snaps are triggered by bifurcations of the equilibrium droplet shape mediated by the underlying non-planar solid. Because the evolution of droplets during snap evaporation is controlled by a smooth topography, and not by surface roughness, our ideas can inspire programmable surfaces that manage liquids in heat- and mass-transfer applications.

Extraction of anthocyanins from red cabbage using high pressure CO2.

PubMed

Xu, Zhenzhen; Wu, Jihong; Zhang, Yan; Hu, Xiaosong; Liao, Xiaojun; Wang, Zhengfu

2010-09-01

The extraction kinetics of anthocyanins from red cabbage using high pressure CO(2) (HPCD) against conventional acidified water (CAW) was investigated. The HPCD time, temperature, pressure and volume ratio of solid-liquid mixture vs. pressurized CO(2) (R((S+L)/G)) exhibited important roles on the extraction kinetics of anthocyanins. The extraction kinetics showed two phases, the yield increased with increasing the time in the first phase, the yield defined as steady-state yield (y(*)) was constant in the second phase. The y(*) of anthocyanins using HPCD increased with higher temperature, higher pressure and lower R((S+L)/G). The general mass transfer model with higher regression coefficients (R(2)>0.97) fitted the kinetic data better than the Fick's second law diffusion model. As compared with CAW, the time (t(*)) to reach the y(*) of anthocyanins using HPCD was reduced by half while its corresponding overall volumetric mass transfer coefficients k(L)xa from the general mass transfer model increased by two folds. Copyright 2010 Elsevier Ltd. All rights reserved.

Competing forces in liquid metal electrodes and batteries

NASA Astrophysics Data System (ADS)

Ashour, Rakan F.; Kelley, Douglas H.; Salas, Alejandro; Starace, Marco; Weber, Norbert; Weier, Tom

2018-02-01

Liquid metal batteries are proposed for low-cost grid scale energy storage. During their operation, solid intermetallic phases often form in the cathode and are known to limit the capacity of the cell. Fluid flow in the liquid electrodes can enhance mass transfer and reduce the formation of localized intermetallics, and fluid flow can be promoted by careful choice of the locations and topology of a battery's electrical connections. In this context we study four phenomena that drive flow: Rayleigh-Bénard convection, internally heated convection, electro-vortex flow, and swirl flow, in both experiment and simulation. In experiments, we use ultrasound Doppler velocimetry (UDV) to measure the flow in a eutectic PbBi electrode at 160 °C and subject to all four phenomena. In numerical simulations, we isolate the phenomena and simulate each separately using OpenFOAM. Comparing simulated velocities to experiments via a UDV beam model, we find that all four phenomena can enhance mass transfer in LMBs. We explain the flow direction, describe how the phenomena interact, and propose dimensionless numbers for estimating their mutual relevance. A brief discussion of electrical connections summarizes the engineering implications of our work.

Transfer of Materials from Water to Solid Surfaces Using Liquid Marbles.

PubMed

Kawashima, Hisato; Paven, Maxime; Mayama, Hiroyuki; Butt, Hans-Jürgen; Nakamura, Yoshinobu; Fujii, Syuji

2017-09-27

Remotely controlling the movement of small objects is desirable, especially for the transportation and selection of materials. Transfer of objects between liquid and solid surfaces and triggering their release would allow for development of novel material transportation technology. Here, we describe the remote transport of a material from a water film surface to a solid surface using quasispherical liquid marbles (LMs). A light-induced Marangoni flow or an air stream is used to propel the LMs on water. As the LMs approach the rim of the water film, gravity forces them to slide down the water rim and roll onto the solid surface. Through this method, LMs can be efficiently moved on water and placed on a solid surface. The materials encapsulated within LMs can be released at a specific time by an external stimulus. We analyzed the velocity, acceleration, and force of the LMs on the liquid and solid surfaces. On water, the sliding friction due to the drag force resists the movement of the LMs. On a solid surface, the rolling distance is affected by the surface roughness of the LMs.

Simulation of Patterned Glass Film Formation in the Evaporating Colloidal Liquid under IR Heating

NASA Astrophysics Data System (ADS)

Kolegov, K. S.

2018-02-01

The paper theoretically studies the method of evaporative lithography in combination with external infrared heating. This method makes it possible to form solid microstructures of the required relief shape as a result of evaporation of the liquid film of the colloidal solution under the mask. The heated particles are sintered easier, so there are no cracks in the obtained structure, unlike the structure obtained employing the standard method of evaporative lithography. The paper puts forward a modification of the mathematical model which allows to describe not only heat and mass transfer at the initial stage of the process, but also the phase transition of colloidal solution into glass. Aqueous latex is taken as an example. The resulting final form of solid film is in good agreement with the experimental data of other authors.

Magneto-Hydrodynamic Damping of Convection During Vertical Bridgman-Stockbarger Growth of HgCdTe

NASA Technical Reports Server (NTRS)

Watring, D. A.; Lehoczky, S. L.

1996-01-01

In order to quantify the effects of convection on segregation, Hg(0.8)Cd(0.2)Te crystals were grown by the vertical Bridgman-Stockbarger method in the presence of an applied axial magnetic field of 50 kG. The influence of convection, by magneto-hydrodynamic damping, on mass transfer in the melt and segregation at the solid-liquid interface was investigated by measuring the axial and radial compositional variations in the grown samples. The reduction of convective mixing in the melt through the application of the magnetic field is found to decrease radial segregation to the diffusion-limited regime. It was also found that the suppression of the convective cell near the solid-liquid interface results in an increase in the slope of the diffusion-controlled solute boundary layer, which can lead to constitutional supercooling.

Thermal power transfer system using applied potential difference to sustain operating pressure difference

NASA Technical Reports Server (NTRS)

Bhandari, Pradeep (Inventor); Fujita, Toshio (Inventor)

1991-01-01

A thermal power transfer system using a phase change liquid gas fluid in a closed loop configuration has a heat exchanger member connected to a gas conduit for inputting thermal energy into the fluid. The pressure in the gas conduit is higher than a liquid conduit that is connected to a heat exchanger member for outputting thermal energy. A solid electrolyte member acts as a barrier between the gas conduit and the liquid conduit adjacent to a solid electrolyte member. The solid electrolyte member has the capacity of transmitting ions of a fluid through the electrolyte member. The ions can be recombined with electrons with the assistance of a porous electrode. An electrical field is applied across the solid electrolyte member to force the ions of the fluid from a lower pressure liquid conduit to the higher pressure gas conduit.

Numerical modelling of heat transfer in a cavity due to liquid jet impingement for liquid supported stretch blow moulding

NASA Astrophysics Data System (ADS)

Smyth, Trevor; Menary, Gary; Geron, Marco

2018-05-01

Impingement of a liquid jet in a polymer cavity has been modelled numerically in this study. Liquid supported stretch blow moulding is a nascent polymer forming process using liquid as the forming medium to produce plastic bottles. The process derives from the conventional stretch blow moulding process which uses compressed air to deform the preform. Heat transfer away from the preform greatly increases when a liquid instead of a gas is flowing over a solid; in the blow moulding process the temperature of the preform is tightly controlled to achieve optimum forming conditions. A model was developed with Computational Fluid Dynamics code ANSYS Fluent which allows the extent of heat transfer between the incoming liquid and the solid preform to be determined in the initial transient stage, where a liquid jet enters an air filled preform. With this data, an approximation of the extent of cooling through the preform wall can be determined.

Numerical analysis of fluid flow and heat transfer during melting inside a cylindrical container for thermal energy storage system

NASA Astrophysics Data System (ADS)

Bellan, Selvan; Cheok, Cho Hyun; Gokon, Nobuyuki; Matsubara, Koji; Kodama, Tatsuya

2017-06-01

This paper presents a numerical analysis of unconstrained melting of high temperature(>1000K) phase change material (PCM) inside a cylindrical container. Sodium chloride and Silicon carbide have been used as phase change material and shell of the capsule respectively. The control volume discretization approach has been used to solve the conservation equations of mass, momentum and energy. The enthalpy-porosity method has been used to track the solid-liquid interface of the PCM during melting process. Transient numerical simulations have been performed in order to study the influence of radius of the capsule and the Stefan number on the heat transfer rate. The simulation results show that the counter-clockwise Buoyancy driven convection over the top part of the solid PCM enhances the melting rate quite faster than the bottom part.

Dependency of the apparent contact angle on nonisothermal conditions

NASA Astrophysics Data System (ADS)

Krahl, Rolf; Gerstmann, Jens; Behruzi, Philipp; Bänsch, Eberhard; Dreyer, Michael E.

2008-04-01

The dynamic behavior of liquids in partly filled containers is influenced to a large extend by the angle between the gas-liquid phase boundary and the solid container wall at the contact line. This contact angle in turn is influenced by nonisothermal conditions. In the case of a cold liquid meniscus spreading over a hot solid wall, the contact angle apparently becomes significantly larger. In this paper we want to establish a quantitative equation for this enlargement, both from experimental and numerical data. Our findings can be used to build a subgrid model for computations, where the resolution is not sufficient to resolve the boundary layers. This might be the case for large containers which are exposed to low accelerations and where the contact angle boundary condition determines the position of the free surface. These types of computation are performed, for example, to solve propellant management problems in launcher and satellite tanks. In this application, the knowledge of the position of the free surface is very important for the withdrawal of liquid and the calculation of heat and mass transfer.

Atomistic modelling of evaporation and explosive boiling of thin film liquid argon over internally recessed nanostructured surface

NASA Astrophysics Data System (ADS)

Hasan, Mohammad Nasim; Shavik, Sheikh Mohammad; Rabbi, Kazi Fazle; Haque, Mominul

2016-07-01

Molecular dynamics (MD) simulations have been carried out to investigate evaporation and explosive boiling phenomena of thin film liquid argon on nanostructured solid surface with emphasis on the effect of solid-liquid interfacial wettability. The nanostructured surface considered herein consists of trapezoidal internal recesses of the solid platinum wall. The wetting conditions of the solid surface were assumed such that it covers both the hydrophilic and hydrophobic conditions and hence effect of interfacial wettability on resulting evaporation and boiling phenomena was the main focus of this study. The initial configuration of the simulation domain comprised of a three phase system (solid platinum, liquid argon and vapor argon) on which equilibrium molecular dynamics (EMD) was performed to reach equilibrium state at 90 K. After equilibrium of the three-phase system was established, the wall was set to different temperatures (130 K and 250 K for the case of evaporation and explosive boiling respectively) to perform non-equilibrium molecular dynamics (NEMD). The variation of temperature and density as well as the variation of system pressure with respect to time were closely monitored for each case. The heat flux normal to the solid surface was also calculated to illustrate the effectiveness of heat transfer for hydrophilic and hydrophobic surfaces in cases of both nanostructured surface and flat surface. The results obtained show that both the wetting condition of the surface and the presence of internal recesses have significant effect on normal evaporation and explosive boiling of the thin liquid film. The heat transfer from solid to liquid in cases of surface with recesses are higher compared to flat surface without recesses. Also the surface with higher wettability (hydrophilic) provides more favorable conditions for boiling than the low-wetting surface (hydrophobic) and therefore, liquid argon responds quickly and shifts from liquid to vapor phase faster in case of hydrophilic surface. The heat transfer rate is also much higher in case of hydrophilic surface.

40 CFR 98.166 - Data reporting requirements.

Code of Federal Regulations, 2010 CFR

2010-07-01

... and transferred off site in either gas, liquid, or solid forms (kg), following the requirements of... in either gas, liquid, or solid forms (kg carbon). ... (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Hydrogen Production § 98.166 Data reporting requirements. In...

Bisphenol A, 4-t-octylphenol, and 4-nonylphenol determination in serum by Hybrid Solid Phase Extraction-Precipitation Technology technique tailored to liquid chromatography-tandem mass spectrometry.

PubMed

Asimakopoulos, Alexandros G; Thomaidis, Nikolaos S

2015-04-01

A rapid liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and optimized for the simultaneous determination of bisphenol A, 4-t-octylphenol and 4-nonylphenol in human blood serum. For the first time, the electrospray ionization (ESI) parameters of probe position, voltage potential, sheath gas flow rate, auxiliary gas flow rate, and ion transfer tube temperature were thoroughly studied and optimized for each phenol by a univariate approach. As a consequence, low instrumental limits of detection were reported, demonstrating at 0.2 ng/mL (in solvent matrix) excellent injection repeatability (RSD<14.5%) and a confirmation peak for all target phenols. Extraction and purification of serum was performed by the novel Hybrid Solid Phase Extraction-Precipitation Technology technique (Hybrid SPE-PPT). The limits of detection in human blood serum were 0.80, 1.3 and 1.4 ng/mL for BPA, 4-t-OP and 4-NP, respectively. Copyright © 2015 Elsevier B.V. All rights reserved.

Interaction between Convection and Heat Transfer in Crystal Growth

NASA Technical Reports Server (NTRS)

1998-01-01

Crystals are integral components in some of our most sophisticated and rapidly developing industries. Single crystals are solids with the most uniform structures that can be obtained on an atomic scale. Because of their structural uniformity, crystals can transmit acoustic and electromagnetic waves and charged particles with essentially no scattering or interferences. This transparency, which can be selectively modified by controlled additions of impurities known as dopants, is the foundation of modern electronic industry. It has brought about widespread application of crystals in transistors, lasers, microwave devices, infrared detectors, magnetic memory devices, and many other magnets and electro-optic components. The performance of a crystal depends strongly on its compositional homogeneity. For instance, in modern microcircuitry, compositional variations of a few percent (down to a submicron length scale) can seriously jeopardize predicted yields. Since crystals are grown by carefully controlled phase transformations, the compositional adjustment in the solid is often made during growth from the nutrient. Hence, a detailed understanding of mass transfer in the nutrient is essential. Moreover, since mass transfer is often the slowest process during growth, it is usually the rate limiting mechanism. Crystal growth processes are usually classified according to the nature of the parent phase. Nevertheless, whether the growth occurs by solidification from a melt (melt growth), nucleation from a solution (solution growth), condensation from a vapor (physical vapor transport) or chemical reaction of gases (chemical vapor deposition), the parent phase is a fluid. As is with most non-equilibrium processes involving fluids, liquid or vapor, fluid motion plays an important role, affecting both the concentration and temperature gradients at the soli-liquid interface.

Evaporative Mass Transfer Behavior of a Complex Immiscible Liquid

PubMed Central

McColl, Colleen M.; Johnson, Gwynn R.; Brusseau, Mark L.

2010-01-01

A series of laboratory experiments was conducted with a multiple-component immiscible liquid, collected from the Picillo Farm Superfund Site in Rhode Island, to examine liquid-vapor mass-transfer behavior. The immiscible liquid, which comprises solvents, oils, pesticides, PCBs, paint sludges, explosives, and other compounds, was characterized using gas chromatography and gas chromatography/mass spectrometry to determine mole fractions of selected constituents. Batch experiments were conducted to evaluate equilibrium phase-partitioning behavior. Two sets of air-stripping column studies were conducted to examine the mass-transfer dynamics of five selected target compounds present in the immiscible-liquid mixture. One set of column experiments was designed to represent a system with free-phase immiscible liquid present; the other was designed to represent a system with a residual phase of immiscible liquid. Initial elution behavior of all target components generally appeared to be ideal for both systems, as the initial vapor-phase concentrations were similar to vapor-phase concentrations measured for the batch experiment and those estimated using Raoult’s law (incorporating the immiscible-liquid composition data). Later-stage removal of 1,2-dichlorobenzene appeared to be rate limited for the columns containing free-phase immiscible liquid and no porous medium. Conversely, evaporative mass transfer appeared to be ideal throughout the experiment conducted with immiscible liquid distributed relatively uniformly as a residual phase within a sandy porous medium. PMID:18614196

Evaporative mass transfer behavior of a complex immiscible liquid.

PubMed

McColl, Colleen M; Johnson, Gwynn R; Brusseau, Mark L

2008-09-01

A series of laboratory experiments was conducted with a multiple-component immiscible liquid, collected from the Picillo Farm Superfund Site in Rhode Island, to examine liquid-vapor mass-transfer behavior. The immiscible liquid, which comprises solvents, oils, pesticides, PCBs, paint sludges, explosives, and other compounds, was characterized using gas chromatography and gas chromatography/mass spectrometry to determine mole fractions of selected constituents. Batch experiments were conducted to evaluate equilibrium phase-partitioning behavior. Two sets of air-stripping column studies were conducted to examine the mass-transfer dynamics of five selected target compounds present in the immiscible-liquid mixture. One set of column experiments was designed to represent a system with free-phase immiscible liquid present; the other was designed to represent a system with a residual phase of immiscible liquid. Initial elution behavior of all target components generally appeared to be ideal for both systems, as the initial vapor-phase concentrations were similar to vapor-phase concentrations measured for the batch experiment and those estimated using Raoult's law (incorporating the immiscible-liquid composition data). Later-stage removal of 1,2-dichlorobenzene appeared to be rate limited for the columns containing free-phase immiscible liquid and no porous medium. Conversely, evaporative mass transfer appeared to be ideal throughout the experiment conducted with immiscible liquid distributed relatively uniformly as a residual phase within a sandy porous medium.

Lagrangian formulation and symmetrical description of liquid dynamics.

PubMed

Trachenko, K

2017-12-01

Theoretical description of liquids has been primarily based on the hydrodynamic approach and its generalization to the solid-like regime. We show that the same liquid properties can be derived starting from solid-like equations and generalizing them to account for the hydrodynamic flow. Both approaches predict propagating shear waves with the notable gap in k-space. This gives an important symmetry of liquids regarding their description. We subsequently construct a two-field Lagrangian of liquid dynamics where the dissipative hydrodynamic and solid-like terms are treated on equal footing. The Lagrangian predicts two gapped waves propagating in opposite space-time directions. The dissipative and mass terms compete by promoting gaps in k-space and energy, respectively. When bare mass is close to the field hopping frequency, both gaps close and the dissipative term annihilates the bare mass.

Lagrangian formulation and symmetrical description of liquid dynamics

NASA Astrophysics Data System (ADS)

Trachenko, K.

2017-12-01

Theoretical description of liquids has been primarily based on the hydrodynamic approach and its generalization to the solid-like regime. We show that the same liquid properties can be derived starting from solid-like equations and generalizing them to account for the hydrodynamic flow. Both approaches predict propagating shear waves with the notable gap in k -space. This gives an important symmetry of liquids regarding their description. We subsequently construct a two-field Lagrangian of liquid dynamics where the dissipative hydrodynamic and solid-like terms are treated on equal footing. The Lagrangian predicts two gapped waves propagating in opposite space-time directions. The dissipative and mass terms compete by promoting gaps in k -space and energy, respectively. When bare mass is close to the field hopping frequency, both gaps close and the dissipative term annihilates the bare mass.

Phase Transformation of Droplets into Particles and Nucleation in Atmospheric Pressure Discharges

NASA Astrophysics Data System (ADS)

Iqbal, M. M.; Stallard, C. P.; Dowling, D. P.; Turner, M. M.

2013-09-01

We investigate the mechanism of phase transformation of liquid precursor droplets into nano-particulates in an atmospheric pressure discharge (APD). This phase transformation is possible when the solid to a liquid mass ratio of slurry droplet reaches a threshold value. The behaviour of phase transformation of a single slurry droplet of HMDSO is described by developing a numerical model under the saturation condition of evaporation. It is observed from the temporal evolution of inner radius (Ri) of a single slurry droplet that its value approaches zero before the entire shifting of a liquid phase and which explains with an expansion in the crust thickness (Ro - Ri) . The solid traces of nano-particles are observed experimentally on the surface coating depositions because the time for transferring the slurry droplet of HMDSO into solid state is amplified with an increment in the radii of droplets and the entire phase transition occurs within residence time for the nano-sized liquid droplets. The GDE coupled with discharge plasma is numerically solved to describe the mechanism of nucleation of nano-sized particles in APD plasma under similar conditions of the experiment. The growth of nucleation in APD plasma depends on the type of liquid precursor, such as HMDSO, TEOS and water, which is verified with a sharp peak in the nucleation rate and saturation ratio. Science Foundation Ireland under Grant No. 08/SRC/I1411.

Concept considerations for a small orbital transfer vehicle

NASA Technical Reports Server (NTRS)

Green, M.; Sibila, A. I.

1979-01-01

This paper summarizes a study of small orbital transfer vehicles to place payloads in orbits with altitudes above those of the standard Shuttle operations. The overall objective of the study is to examine the role of the small orbital transfer vehicle (SOTV) in Shuttle operations and to identify typical propulsion concepts for accomplishing the mission. Consideration is given to existing and planned systems and upper stages, along with new propulsion stages. The new propulsion concept development examines tandem and clustered solids, controlled solids, monopropellant and bipropellant liquids, and staged solid/liquid combinations. The paper presents considerations of the mission requirements, tradeoffs of the various configurations, and candidate selections. For the selected candidate concepts the performance, support equipment, operational considerations and program costs were determined. The results show that a new modular liquid stage system is cost effective in handling the majority of the payloads considered. The remainder of the payloads can be accomodated by existing systems.

Mass transfer in thin films under counter-current gas: experiments and numerical study

NASA Astrophysics Data System (ADS)

Lucquiaud, Mathieu; Lavalle, Gianluca; Schmidt, Patrick; Ausner, Ilja; Wehrli, Marc; O Naraigh, Lennon; Valluri, Prashant

2016-11-01

Mass transfer in liquid-gas stratified flows is strongly affected by the waviness of the interface. For reactive flows, the chemical reactions occurring at the liquid-gas interface also influence the mass transfer rate. This is encountered in several technological applications, such as absorption units for carbon capture. We investigate the absorption rate of carbon dioxide in a liquid solution. The experimental set-up consists of a vertical channel where a falling film is sheared by a counter-current gas flow. We measure the absorption occurring at different flow conditions, by changing the liquid solution, the liquid flow rate and the gas composition. With the aim to support the experimental results with numerical simulations, we implement in our level-set flow solver a novel module for mass transfer taking into account a variant of the ghost-fluid formalism. We firstly validate the pure mass transfer case with and without hydrodynamics by comparing the species concentration in the bulk flow to the analytical solution. In a final stage, we analyse the absorption rate in reactive flows, and try to reproduce the experimental results by means of numerical simulations to explore the active role of the waves at the interface.

Time-Resolved and Operando XAS Studies on Heterogeneous Catalysts - From the Gas Phase Towards Reactions in Supercritical Fluids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grunwaldt, Jan-Dierk; Baiker, Alfons

2007-02-02

x-ray absorption spectroscopy is a well-suited technique to uncover the structure of heterogeneous catalysts under reaction conditions. Different aspects of in situ cell design suitable for dynamic and catalytic studies are discussed. In addition, criteria are presented that allow estimating the influence external and internal mass transfer. Starting with studies on gas-solid reactions, including structure-activity relationships, this concept is extended to liquid-solid reactions, reactions at high pressure and in supercritical fluids. The following examples are discussed in more detail: partial oxidation of methane over Pt-Rh/Al2O3, reduction of a Cu/ZnO catalyst, alcohol oxidation over Bi-promoted Pd/Al2O3 in liquid phase and overmore » Pd/Al2O3 in supercritical CO2, and batch reactions (e.g. CO2-fixation over zinc-based catalysts)« less

Ultrasound in gas-liquid systems: effects on solubility and mass transfer.

PubMed

Laugier, F; Andriantsiferana, C; Wilhelm, A M; Delmas, H

2008-09-01

The effect of ultrasound on the pseudo-solubility of nitrogen in water and on gas-liquid mass transfer kinetics has been investigated in an autoclave reactor equipped with a gas induced impeller. In order to use organic liquids and to investigate the effect of pressure, gas-liquid mass transfer coefficient was calculated from the evolution of autoclave pressure during gas absorption to avoid any side-effects of ultrasound on the concentrations measurements. Ultrasound effect on the apparent solubility is very low (below 12%). Conversely ultrasound greatly improves gas-liquid mass transfer, especially below gas induction speed, this improvement being boosted by pressure. In typical conditions of organic synthesis: 323 K, 1100 rpm, 10 bar, k(L).a is multiplied by 11 with ultrasound (20 kHz/62.6 W). The impact of sonication is much higher on gassing out than on gassing in. In the same conditions, this enhancement is at least five times higher for degassing.

Enthalpy-based multiple-relaxation-time lattice Boltzmann method for solid-liquid phase-change heat transfer in metal foams.

PubMed

Liu, Qing; He, Ya-Ling; Li, Qing

2017-08-01

In this paper, an enthalpy-based multiple-relaxation-time (MRT) lattice Boltzmann (LB) method is developed for solid-liquid phase-change heat transfer in metal foams under the local thermal nonequilibrium (LTNE) condition. The enthalpy-based MRT-LB method consists of three different MRT-LB models: one for flow field based on the generalized non-Darcy model, and the other two for phase-change material (PCM) and metal-foam temperature fields described by the LTNE model. The moving solid-liquid phase interface is implicitly tracked through the liquid fraction, which is simultaneously obtained when the energy equations of PCM and metal foam are solved. The present method has several distinctive features. First, as compared with previous studies, the present method avoids the iteration procedure; thus it retains the inherent merits of the standard LB method and is superior to the iteration method in terms of accuracy and computational efficiency. Second, a volumetric LB scheme instead of the bounce-back scheme is employed to realize the no-slip velocity condition in the interface and solid phase regions, which is consistent with the actual situation. Last but not least, the MRT collision model is employed, and with additional degrees of freedom, it has the ability to reduce the numerical diffusion across the phase interface induced by solid-liquid phase change. Numerical tests demonstrate that the present method can serve as an accurate and efficient numerical tool for studying metal-foam enhanced solid-liquid phase-change heat transfer in latent heat storage. Finally, comparisons and discussions are made to offer useful information for practical applications of the present method.

Enthalpy-based multiple-relaxation-time lattice Boltzmann method for solid-liquid phase-change heat transfer in metal foams

NASA Astrophysics Data System (ADS)

Liu, Qing; He, Ya-Ling; Li, Qing

2017-08-01

In this paper, an enthalpy-based multiple-relaxation-time (MRT) lattice Boltzmann (LB) method is developed for solid-liquid phase-change heat transfer in metal foams under the local thermal nonequilibrium (LTNE) condition. The enthalpy-based MRT-LB method consists of three different MRT-LB models: one for flow field based on the generalized non-Darcy model, and the other two for phase-change material (PCM) and metal-foam temperature fields described by the LTNE model. The moving solid-liquid phase interface is implicitly tracked through the liquid fraction, which is simultaneously obtained when the energy equations of PCM and metal foam are solved. The present method has several distinctive features. First, as compared with previous studies, the present method avoids the iteration procedure; thus it retains the inherent merits of the standard LB method and is superior to the iteration method in terms of accuracy and computational efficiency. Second, a volumetric LB scheme instead of the bounce-back scheme is employed to realize the no-slip velocity condition in the interface and solid phase regions, which is consistent with the actual situation. Last but not least, the MRT collision model is employed, and with additional degrees of freedom, it has the ability to reduce the numerical diffusion across the phase interface induced by solid-liquid phase change. Numerical tests demonstrate that the present method can serve as an accurate and efficient numerical tool for studying metal-foam enhanced solid-liquid phase-change heat transfer in latent heat storage. Finally, comparisons and discussions are made to offer useful information for practical applications of the present method.

Mass Transfer with Chemical Reaction.

ERIC Educational Resources Information Center

DeCoursey, W. J.

1987-01-01

Describes the organization of a graduate course dealing with mass transfer, particularly as it relates to chemical reactions. Discusses the course outline, including mathematics models of mass transfer, enhancement of mass transfer rates by homogeneous chemical reaction, and gas-liquid systems with chemical reaction. (TW)

Ozone mass transfer behaviors on physical and chemical absorption for hollow fiber membrane contactors.

PubMed

Zhang, Yong; Li, Kuiling; Wang, Jun; Hou, Deyin; Liu, Huijuan

2017-09-01

To understand the mass transfer behaviors in hollow fiber membrane contactors, ozone fluxes affected by various conditions and membranes were investigated. For physical absorption, mass transfer rate increased with liquid velocity and the ozone concentration in the gas. Gas flow rate was little affected when the velocity was larger than the critical value, which was 6.1 × 10 -3 m/s in this study. For chemical absorption, the flux was determined by the reaction rate between ozone and the absorbent. Therefore, concentration, species, and pH affected the mass transfer process markedly. For different absorbents, the order of mass transfer rate was the same as the reaction rate constant, which was phenol, sodium nitrite, hydrogen peroxide, and oxalate. Five hydrophobic membranes with various properties were employed and the mass transfer behavior can be described by the Graetz-Lévèque equation for the physical absorption process. The results showed the process was controlled by liquid film and the gas phase conditions, and membrane properties did not affect the ozone flux. For the chemical absorption, gas film, membrane and liquid film affected the mass transfer together, and none of them were negligible.

Atomistic modelling of evaporation and explosive boiling of thin film liquid argon over internally recessed nanostructured surface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hasan, Mohammad Nasim, E-mail: nasim@me.buet.ac.bd.com; Shavik, Sheikh Mohammad, E-mail: shavik@me.buet.ac.bd.com; Rabbi, Kazi Fazle, E-mail: rabbi35.me10@gmail.com

2016-07-12

Molecular dynamics (MD) simulations have been carried out to investigate evaporation and explosive boiling phenomena of thin film liquid argon on nanostructured solid surface with emphasis on the effect of solid-liquid interfacial wettability. The nanostructured surface considered herein consists of trapezoidal internal recesses of the solid platinum wall. The wetting conditions of the solid surface were assumed such that it covers both the hydrophilic and hydrophobic conditions and hence effect of interfacial wettability on resulting evaporation and boiling phenomena was the main focus of this study. The initial configuration of the simulation domain comprised of a three phase system (solidmore » platinum, liquid argon and vapor argon) on which equilibrium molecular dynamics (EMD) was performed to reach equilibrium state at 90 K. After equilibrium of the three-phase system was established, the wall was set to different temperatures (130 K and 250 K for the case of evaporation and explosive boiling respectively) to perform non-equilibrium molecular dynamics (NEMD). The variation of temperature and density as well as the variation of system pressure with respect to time were closely monitored for each case. The heat flux normal to the solid surface was also calculated to illustrate the effectiveness of heat transfer for hydrophilic and hydrophobic surfaces in cases of both nanostructured surface and flat surface. The results obtained show that both the wetting condition of the surface and the presence of internal recesses have significant effect on normal evaporation and explosive boiling of the thin liquid film. The heat transfer from solid to liquid in cases of surface with recesses are higher compared to flat surface without recesses. Also the surface with higher wettability (hydrophilic) provides more favorable conditions for boiling than the low-wetting surface (hydrophobic) and therefore, liquid argon responds quickly and shifts from liquid to vapor phase faster in case of hydrophilic surface. The heat transfer rate is also much higher in case of hydrophilic surface.« less

Combined heat and mass transfer device for improving separation process

DOEpatents

Tran, Thanh Nhon

1999-01-01

A two-phase small channel heat exchange matrix simultaneously provides for heat transfer and mass transfer between the liquid and vapor phases of a multi-component mixture at a single, predetermined location within a separation column, significantly improving the thermodynamic efficiency of the separation process. The small channel heat exchange matrix is composed of a series of channels having a hydraulic diameter no greater than 5.0 millimeters for conducting a two-phase coolant. In operation, the matrix provides the liquid-vapor contacting surfaces within the separation column, such that heat and mass are transferred simultaneously between the liquid and vapor phases. The two-phase coolant allows for a uniform heat transfer coefficient to be maintained along the length of the channels and across the surface of the matrix. Preferably, a perforated, concave sheet connects each channel to an adjacent channel to facilitate the flow of the liquid and vapor phases within the column and to increase the liquid-vapor contacting surface area.

Combined heat and mass transfer device for improving separation process

DOEpatents

Tran, T.N.

1999-08-24

A two-phase small channel heat exchange matrix simultaneously provides for heat transfer and mass transfer between the liquid and vapor phases of a multi-component mixture at a single, predetermined location within a separation column, significantly improving the thermodynamic efficiency of the separation process. The small channel heat exchange matrix is composed of a series of channels having a hydraulic diameter no greater than 5.0 millimeters for conducting a two-phase coolant. In operation, the matrix provides the liquid-vapor contacting surfaces within the separation column, such that heat and mass are transferred simultaneously between the liquid and vapor phases. The two-phase coolant allows for a uniform heat transfer coefficient to be maintained along the length of the channels and across the surface of the matrix. Preferably, a perforated, concave sheet connects each channel to an adjacent channel to facilitate the flow of the liquid and vapor phases within the column and to increase the liquid-vapor contacting surface area. 12 figs.

Correlation of chemical evaporation rate with vapor pressure.

PubMed

Mackay, Donald; van Wesenbeeck, Ian

2014-09-02

A new one-parameter correlation is developed for the evaporation rate (ER) of chemicals as a function of molar mass (M) and vapor pressure (P) that is simpler than existing correlations. It applies only to liquid surfaces that are unaffected by the underlying solid substrate as occurs in the standard ASTM evaporation rate test and to quiescent liquid pools. The relationship has a sounder theoretical basis than previous correlations because ER is correctly correlated with PM rather than P alone. The inclusion of M increases the slope of previous log ER versus log P regressions to a value close to 1.0 and yields a simpler one-parameter correlation, namely, ER (μg m(-1) h(-1)) = 1464P (Pa) × M (g mol(-1)). Applications are discussed for the screening level assessment and ranking of chemicals for evaporation rate, such as pesticides, fumigants, and hydrocarbon carrier fluids used in pesticide formulations, liquid consumer products used indoors, and accidental spills of liquids. The mechanistic significance of the single parameter as a mass-transfer coefficient or velocity is discussed.

Associations between added sugar (solid vs. liquid) intakes, diet quality, and adiposity indicators in Canadian children.

PubMed

Wang, JiaWei; Shang, Lei; Light, Kelly; O'Loughlin, Jennifer; Paradis, Gilles; Gray-Donald, Katherine

2015-08-01

Little is known about the influence of different forms of added sugar intake on diet quality or their association with obesity among youth. Dietary intake was assessed by three 24-h recalls in 613 Canadian children (aged 8-10 years). Added sugars (mean of 3-day intakes) were categorized according to source (solid or liquid). Dietary intake and the Canadian Healthy Eating Index (« HEI-C ») were compared across tertiles of solid and liquid added sugars separately as were adiposity indicators (body mass index (BMI), fat mass (dual-energy X-ray absorptiometry), and waist circumference). Cross-sectional associations were examined in linear regression models adjusting for age, sex, energy intake, and physical activity (7-day accelerometer). Added sugar contributed 12% of total energy intake (204 kcal) on average, of which 78% was from solid sources. Higher consumption of added sugars from either solid or liquid source was associated with higher total energy, lower intake of micronutrients, vegetables and fruit, and lower HEI-C score. Additionally liquid sources were associated with lower intake of dairy products. A 10-g higher consumption of added sugars from liquid sources was associated with 0.4 serving/day lower of vegetables and fruit, 0.4-kg/m(2) higher BMI, a 0.5-kg higher fat mass, and a 0.9-cm higher waist circumference whereas the associations of added sugars from solid sources and adiposity indicators tended to be negative. In conclusion, higher consumption of added sugar from either solid or liquid sources was associated with lower overall diet quality. Adiposity indicators were only positively associated with added sugars from liquid sources.

Designs and test results for three new rotational sensors

USGS Publications Warehouse

Jedlicka, P.; Kozak, J.T.; Evans, J.R.; Hutt, C.R.

2012-01-01

We discuss the designs and testing of three rotational seismometer prototypes developed at the Institute of Geophysics, Academy of Sciences (Prague, Czech Republic). Two of these designs consist of a liquid-filled toroidal tube with the liquid as the proof mass and providing damping; we tested the piezoelectric and pressure transduction versions of this torus. The third design is a wheel-shaped solid metal inertial sensor with capacitive sensing and magnetic damping. Our results from testing in Prague and at the Albuquerque Seismological Laboratory of the US Geological Survey of transfer function and cross-axis sensitivities are good enough to justify the refinement and subsequent testing of advanced prototypes. These refinements and new testing are well along.

Designs and test results for three new rotational sensors

NASA Astrophysics Data System (ADS)

Jedlička, P.; Kozák, J. T.; Evans, J. R.; Hutt, C. R.

2012-10-01

We discuss the designs and testing of three rotational seismometer prototypes developed at the Institute of Geophysics, Academy of Sciences (Prague, Czech Republic). Two of these designs consist of a liquid-filled toroidal tube with the liquid as the proof mass and providing damping; we tested the piezoelectric and pressure transduction versions of this torus. The third design is a wheel-shaped solid metal inertial sensor with capacitive sensing and magnetic damping. Our results from testing in Prague and at the Albuquerque Seismological Laboratory of the US Geological Survey of transfer function and cross-axis sensitivities are good enough to justify the refinement and subsequent testing of advanced prototypes. These refinements and new testing are well along.

Numerical analysis of heat and mass transfer for water recovery in an evaporative cooling tower

NASA Astrophysics Data System (ADS)

Lee, Hyunsub; Son, Gihun

2017-11-01

Numerical analysis is performed for water recovery in an evaporative cooling tower using a condensing heat exchanger, which consists of a humid air channel and an ambient dry air channel. The humid air including water vapor produced in an evaporative cooling tower is cooled by the ambient dry air so that the water vapor is condensed and recovered to the liquid water. The conservation equations of mass, momentum, energy and vapor concentration in each fluid region and the energy equation in a solid region are simultaneously solved with the heat and mass transfer boundary conditions coupled to the effect of condensation on the channel surface of humid air. The present computation demonstrates the condensed water film distribution on the humid air channel, which is caused by the vapor mass transfer between the humid air and the colder water film surface, which is coupled to the indirect heat exchange with the ambient air. Computations are carried out to predict water recovery rate in parallel, counter and cross-flow type heat exchangers. The effects of air flow rate and channel interval on the water recovery rate are quantified.

Compatibility of materials with liquid metal targets for SNS

DOE Office of Scientific and Technical Information (OSTI.GOV)

DiStefano, J.R.; Pawel, S.J.; DeVan, J.H.

1996-06-01

Several heavy liquid metals are candidates as the target in a spallation neutron source: Hg, Pb, Bi, and Pb-Bi eutectic. Systems with these liquid metals have been used in the past and a data-base on compatibility already exists. Two major compatibility issues have been identified when selecting a container material for these liquid metals: temperature gradient mass transfer and liquid metal embrittlement or LME. Temperature gradient mass transfer refers to dissolution of material from the high temperature portions of a system and its deposition in the lower temperature areas. Solution and deposition rate constants along with temperature, {Delta}T, and velocitymore » are usually the most important parameters. For most candidate materials mass transfer corrosion has been found to be proportionately worse in Bi compared with Hg and Pb. For temperatures to {approx}550{degrees}C, ferritic/martensitic steels have been satisfactory in Pb or Hg systems and the maximum temperature can be extended to {approx}650{degrees}C with additions of inhibitors to the liquid metal, e.g. Mg, Ti, Zr. Above {approx}600{degrees}C, austenitic stainless steels have been reported to be unsatisfactory, largely because of the mass transfer of nickel. Blockage of flow from deposition of material is usually the life-limiting effect of this type of corrosion. However, mass transfer corrosion at lower temperatures has not been studied. At low temperatures (usually < 150{degrees}C), LME has been reported for some liquid metal/container alloy combinations. Liquid metal embrittlement, like hydrogen embrittlement, results in brittle fracture of a normally ductile material.« less

Pseudo-transient heat transfer in vertical Bridgman crystal growth of semi-transparent materials

NASA Astrophysics Data System (ADS)

Barvinschi, F.; Nicoara, I.; Santailler, J. L.; Duffar, T.

1998-11-01

The temperature distribution and the solid-liquid interface shape during semi-transparent crystal growth have been studied by modelling a vertical Bridgman technique, using a pseudo-transient approximation in an ideal configuration. The heat transfer equation and the boundary conditions have been solved by the finite-element method. It has been pointed out that the optical absorption coefficients of the liquid and solid phases have a major effect on the thermal field, especially on the shape and location of the crystallization interface.

Comparison of heat transfer in liquid and slush nitrogen by numerical simulation of cooling rates for French straws used for sperm cryopreservation.

PubMed

Sansinena, M; Santos, M V; Zaritzky, N; Chirife, J

2012-05-01

Slush nitrogen (SN(2)) is a mixture of solid nitrogen and liquid nitrogen, with an average temperature of -207 °C. To investigate whether plunging a French plastic straw (commonly used for sperm cryopreservation) in SN(2) substantially increases cooling rates with respect to liquid nitrogen (LN(2)), a numerical simulation of the heat conduction equation with convective boundary condition was used to predict cooling rates. Calculations performed using heat transfer coefficients in the range of film boiling confirmed the main benefit of plunging a straw in slush over LN(2) did not arise from their temperature difference (-207 vs. -196 °C), but rather from an increase in the external heat transfer coefficient. Numerical simulations using high heat transfer (h) coefficients (assumed to prevail in SN(2)) suggested that plunging in SN(2) would increase cooling rates of French straw. This increase of cooling rates was attributed to a less or null film boiling responsible for low heat transfer coefficients in liquid nitrogen when the straw is placed in the solid-liquid mixture or slush. In addition, predicted cooling rates of French straws in SN(2) tended to level-off for high h values, suggesting heat transfer was dictated by heat conduction within the liquid filled plastic straw. Copyright © 2012 Elsevier Inc. All rights reserved.

Determination of the mass-transfer coefficient in liquid phase in a stream-bubble contact device

NASA Astrophysics Data System (ADS)

Dmitriev, A. V.; Dmitrieva, O. S.; Madyshev, I. N.

2016-09-01

One of the most effective energy saving technologies is the improvement of existing heat and mass exchange units. A stream-bubble contact device is designed to enhance the operation efficiency of heat and mass exchange units. The stages of the stream-bubble units that are proposed by the authors for the decarbonization process comprise contact devices with equivalent sizes, whose number is determined by the required performance of a unit. This approach to the structural design eliminates the problems that arise upon the transition from laboratory samples to industrial facilities and makes it possible to design the units of any required performance without a decrease in the effectiveness of mass exchange. To choose the optimal design that provides the maximum effectiveness of the mass-exchange processes in units and their intensification, the change of the mass-transfer coefficient is analyzed with the assumption of a number of parameters. The results of the study of the effect of various structural parameters of a stream-bubble contact device on the mass-transfer coefficient in the liquid phase are given. It is proven that the mass-transfer coefficient increases in the liquid phase, in the first place, with the growth of the level of liquid in the contact element, because the rate of the liquid run-off grows in this case and, consequently, the time of surface renewal is reduced; in the second place, with an increase in the slot diameter in the downpipe, because the jet diameter and, accordingly, their section perimeter and the area of the surface that is immersed in liquid increase; and, in the third place, with an increase in the number of slots in the downpipe, because the area of the surface that is immersed in the liquid of the contact element increases. Thus, in order to increase the mass-transfer coefficient in the liquid phase, it is necessary to design the contact elements with a minimum width and a large number of slots and their increased diameter; in this case, the filling degree of contact elements by the liquid must be maximum.

40 CFR 98.166 - Data reporting requirements.

Code of Federal Regulations, 2013 CFR

2013-07-01

... CO2 collected and transferred off site in either gas, liquid, or solid forms, following the... off site in either gas, liquid, or solid forms (kg carbon). [74 FR 56374, Oct. 30, 2009, as amended at... (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Hydrogen Production § 98.166 Data reporting requirements. In...

40 CFR 98.166 - Data reporting requirements.

Code of Federal Regulations, 2012 CFR

2012-07-01

... CO2 collected and transferred off site in either gas, liquid, or solid forms, following the... off site in either gas, liquid, or solid forms (kg carbon). [74 FR 56374, Oct. 30, 2009, as amended at... (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Hydrogen Production § 98.166 Data reporting requirements. In...

40 CFR 98.166 - Data reporting requirements.

Code of Federal Regulations, 2011 CFR

2011-07-01

... CO2 collected and transferred off site in either gas, liquid, or solid forms, following the... off site in either gas, liquid, or solid forms (kg carbon). [74 FR 56374, Oct. 30, 2009, as amended at... (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Hydrogen Production § 98.166 Data reporting requirements. In...

Transport of viruses through saturated and unsaturated columns packed with sand

USGS Publications Warehouse

Anders, R.; Chrysikopoulos, C.V.

2009-01-01

Laboratory-scale virus transport experiments were conducted in columns packed with sand under saturated and unsaturated conditions. The viruses employed were the male-specific RNA coliphage, MS2, and the Salmonella typhimurium phage, PRD1. The mathematical model developed by Sim and Chrysikopoulos (Water Resour Res 36:173-179, 2000) that accounts for processes responsible for removal of viruses during vertical transport in one-dimensional, unsaturated porous media was used to fit the data collected from the laboratory experiments. The liquid to liquid-solid and liquid to air-liquid interface mass transfer rate coefficients were shown to increase for both bacteriophage as saturation levels were reduced. The experimental results indicate that even for unfavorable attachment conditions within a sand column (e.g., phosphate-buffered saline solution; pH = 7.5; ionic strength = 2 mM), saturation levels can affect virus transport through porous media. ?? Springer Science+Business Media B.V. 2008.

Ultrapressure liquid chromatography-tandem mass spectrometry assay using atmospheric pressure photoionization (UPLC-APPI-MS/MS) for quantification of 4-methoxydiphenylmethane in pharmacokinetic evaluation.

PubMed

Farhan, Nashid; Fitzpatrick, Sean; Shim, Yun M; Paige, Mikell; Chow, Diana Shu-Lian

2016-09-05

4-Methoxydiphenylmethane (4-MDM), a selective augmenter of Leukotriene A4 Hydrolase (LTA4H), is a new anti-inflammatory compound for potential treatment of chronic obstructive pulmonary disease (COPD). Currently, there is no liquid chromatography tandem mass spectrometric (LC-MS/MS) method for the quantification of 4-MDM. A major barrier for developing the LC-MS/MS method is the inability of electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) to ionize 4-MDM due to its hydrophobicity and lack of any functional group for ionization. With the advent of atmospheric pressure photoionization (APPI) technique, many hydrophobic compounds have been demonstrated to ionize by charge transfer reactions. In this study, a highly sensitive ultrapressure liquid chromatography tandem mass spectrometry assay using atmospheric pressure photoionization (UPLC-APPI-MS/MS) for the quantifications of 4-MDM in rat plasma has been developed and validated. 4-MDM was extracted from the plasma by solid phase extraction (SPE) and separated chromatographically using a reverse phase C8 column. The photoionization (PI) was achieved by introducing anisole as a dopant to promote the reaction of charge transfer. The assay with a linear range of 5 (LLOQ)-400ngmL(-1) met the regulatory requirements for accuracy, precision and stability. The validated assay was employed to quantify the plasma concentrations of 4-MDM after an oral dosing in Sprague Dawley (SD) rats. Copyright © 2016 Elsevier B.V. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lobo, R.; Revah, S.; Viveros-Garcia, T.

An analysis of the local processes occurring in a trickle-bed bioreactor (TBB) with a first-order bioreaction shows that the identification of the TBB operating regime requires knowledge of the substrate concentration in the liquid phase. If the substrate liquid concentration is close to 0, the rate-controlling step is mass transfer at the gas-liquid interface; when it is close to the value in equilibrium with the gas phase, the controlling step is the phenomena occurring in the biofilm, CS{sub 2} removal rate data obtained in a TBB with a Thiobacilii consortia biofilm are analyzed to obtain the mass transfer and kineticmore » parameters, and to show that the bioreactor operates in a regime mainly controlled by mass transfer. A TBB model with two experimentally determined parameters is developed and used to show how the bioreactor size depends on the rate-limiting step, the absorption factor, the substrate fractional conversion, and on the gas and liquid contact pattern. Under certain conditions, the TBB size is independent of the flowing phases` contact pattern. The model effectively describes substrate gas and liquid concentration data for mass transfer and biodegradation rate controlled processes.« less

Intrinsic kinetic parameters of substrate utilization by immobilized anaerobic sludge.

PubMed

Zaiat, M; Vieira, L G; Foresti, E

1997-01-20

This article presents a method for evaluating the intrinsic kinetic parameters of the specific substrate utilization rate (r) equation and discusses the results obtained for anaerobic sludge-bed samples taken from a horizontal-flow anaerobic immobilized sludge (HAIS) reactor. This method utilizes a differential reactor filled with polyurethane foam matrices containing immobilized anaerobic sludge which is subjected to a range of feeding substrate flow rates. The range of liquid superficial velocities thus obtained are used for generating data of observed specific substrate utilization rates (r(obs)) under a diversity of external mass transfer resistance conditions. The r(obs) curves are then adjusted to permit their extrapolation for the condition of no external mass transfer resistance, and the values determined are used as a test for the condition of absence of limitation of internal mass transfer. The intrinsic parameters r(max), the maximum specific substrate utilization rate, and K(s), the half-velocity coefficient, are evaluated from the r values under no external mass transfer resistance and no internal mass transfer limitation. The application of such a method for anaerobic sludge immobilized in polyurethane foam particles treating a glucose substrate at 30 degrees C resulted in intrinsic r(max) and K(s), respectively, of 0.330 mg chemical oxygen demand (COD) . mg(-1) volatile suspended solids (VSS) . h(-1) and 72 mg COD . L(-1). In comparison with the values found in the literature, intrinsic r(max) is significantly high and intrinsic K(s) is relatively low. (c) 1997 John Wiley & Sons, Inc.

Theoretical models for supercritical fluid extraction.

PubMed

Huang, Zhen; Shi, Xiao-Han; Jiang, Wei-Juan

2012-08-10

For the proper design of supercritical fluid extraction processes, it is essential to have a sound knowledge of the mass transfer mechanism of the extraction process and the appropriate mathematical representation. In this paper, the advances and applications of kinetic models for describing supercritical fluid extraction from various solid matrices have been presented. The theoretical models overviewed here include the hot ball diffusion, broken and intact cell, shrinking core and some relatively simple models. Mathematical representations of these models have been in detail interpreted as well as their assumptions, parameter identifications and application examples. Extraction process of the analyte solute from the solid matrix by means of supercritical fluid includes the dissolution of the analyte from the solid, the analyte diffusion in the matrix and its transport to the bulk supercritical fluid. Mechanisms involved in a mass transfer model are discussed in terms of external mass transfer resistance, internal mass transfer resistance, solute-solid interactions and axial dispersion. The correlations of the external mass transfer coefficient and axial dispersion coefficient with certain dimensionless numbers are also discussed. Among these models, the broken and intact cell model seems to be the most relevant mathematical model as it is able to provide realistic description of the plant material structure for better understanding the mass-transfer kinetics and thus it has been widely employed for modeling supercritical fluid extraction of natural matters. Copyright © 2012 Elsevier B.V. All rights reserved.

[Heat transfer analysis of liquid cooling garment used for extravehicular activity].

PubMed

Qiu, Y F; Yuan, X G; Mei, Z G; Jia, S G; Ouyang, H; Ren, Z S

2001-10-01

Brief description was given about the construction and function of the LCG (liquid cooling garment) used for EVA (extravehicular activity). The heat convection was analyzed between ventilating gas and LCG, the heat and mass transfer process was analyzed too, then a heat and mass transfer mathematical model of LCG was developed. Thermal physiological experimental study with human body wearing LVCG (liquid cooling and ventilation garment) used for EVA was carried out to verify this mathematical model. This study provided a basis for the design of liquid-cooling and ventilation system for the space suit.

Note on heat conduction in liquid metals. A comparison of laminar and turbulent flow effects

NASA Astrophysics Data System (ADS)

Talmage, G.

1994-05-01

The difference between heat transfer in liquid metals with electric currents and magnetic fields on the one hand and heat transfer in electrically insulating fluids and in conducting solids on the other is pointed out. Laminar and turbulent flow effects in liquid metal sliding electric contacts for homopolar machines are considered. Large temperature gradients can develop within a small region of liquid metal. A model of a liquid-metal sliding electrical contact is developed and analyzed.

Solid/liquid extraction equilibria of phenolic compounds with trioctylphosphine oxide impregnated in polymeric membranes.

PubMed

Praveen, Prashant; Loh, Kai-Chee

2016-06-01

Trioctylphosphine oxide based extractant impregnated membranes (EIM) were used for extraction of phenol and its methyl, hydroxyl and chloride substituted derivatives. The distribution coefficients of the phenols varied from 2 to 234, in the order of 1-napthol > p-chlorophenol > m-cresol > p-cresol > o-cresol > phenol > catechol > pyrogallol > hydroquinone, when initial phenols loadings was varied in 100-2000 mg/L. An extraction model, based on the law of mass action, was formulated to predict the equilibrium distribution of the phenols. The model was in excellent agreement (R(2) > 0.97) with the experimental results at low phenols concentrations (<800 mg/L). At higher phenols loadings though, Langmuir isotherm was better suited for equilibrium prediction (R(2) > 0.95), which signified high mass transfer resistance in the EIMs. Examination of the effects of ring substitution on equilibrium, and bivariate statistical analysis between the amounts of phenols extracted into the EIMs and factors affecting phenols interaction with TOPO, indicated the dominant role of hydrophobicity in equilibrium determination. These results improve understanding of the solid/liquid equilibrium process between phenols and the EIMs, and these will be useful in designing phenol recovery process from wastewater. Copyright © 2016 Elsevier Ltd. All rights reserved.

Electrochemical ion transfer across liquid/liquid interfaces confined within solid-state micropore arrays--simulations and experiments.

PubMed

Strutwolf, Jörg; Scanlon, Micheál D; Arrigan, Damien W M

2009-01-01

Miniaturised liquid/liquid interfaces provide benefits for bioanalytical detection with electrochemical methods. In this work, microporous silicon membranes which can be used for interface miniaturisation were characterized by simulations and experiments. The microporous membranes possessed hexagonal arrays of pores with radii between 10 and 25 microm, a pore depth of 100 microm and pore centre-to-centre separations between 99 and 986 microm. Cyclic voltammetry was used to monitor ion transfer across arrays of micro-interfaces between two immiscible electrolyte solutions (microITIES) formed at these membranes, with the organic phase present as an organogel. The results were compared to computational simulations taking into account mass transport by diffusion and encompassing diffusion to recessed interfaces and overlapped diffusion zones. The simulation and experimental data were both consistent with the situation where the location of the liquid/liquid (l/l) interface was on the aqueous side of the silicon membrane and the pores were filled with the organic phase. While the current for the forward potential scan (transfer of the ion from the aqueous phase to the organic phase) was strongly dependent on the location of the l/l interface, the current peak during the reverse scan (transfer of the ion from the organic phase to the aqueous phase) was influenced by the ratio of the transferring ion's diffusion coefficients in both phases. The diffusion coefficient of the transferring ion in the gelified organic phase was ca. nine times smaller than in the aqueous phase. Asymmetric cyclic voltammogram shapes were caused by the combined effect of non-symmetrical diffusion (spherical and linear) and by the inequality of the diffusion coefficient in both phases. Overlapping diffusion zones were responsible for the observation of current peaks instead of steady-state currents during the forward scan. The characterisation of the diffusion behaviour is an important requirement for application of these silicon membranes in electroanalytical chemistry.

Investigation of mass transfer intensification under power ultrasound irradiation using 3D computational simulation: A comparative analysis.

PubMed

Sajjadi, Baharak; Asgharzadehahmadi, Seyedali; Asaithambi, Perumal; Raman, Abdul Aziz Abdul; Parthasarathy, Rajarathinam

2017-01-01

This paper aims at investigating the influence of acoustic streaming induced by low-frequency (24kHz) ultrasound irradiation on mass transfer in a two-phase system. The main objective is to discuss the possible mass transfer improvements under ultrasound irradiation. Three analyses were conducted: i) experimental analysis of mass transfer under ultrasound irradiation; ii) comparative analysis between the results of the ultrasound assisted mass transfer with that obtained from mechanically stirring; and iii) computational analysis of the systems using 3D CFD simulation. In the experimental part, the interactive effects of liquid rheological properties, ultrasound power and superficial gas velocity on mass transfer were investigated in two different sonicators. The results were then compared with that of mechanical stirring. In the computational part, the results were illustrated as a function of acoustic streaming behaviour, fluid flow pattern, gas/liquid volume fraction and turbulence in the two-phase system and finally the mass transfer coefficient was specified. It was found that additional turbulence created by ultrasound played the most important role on intensifying the mass transfer phenomena compared to that in stirred vessel. Furthermore, long residence time which depends on geometrical parameters is another key for mass transfer. The results obtained in the present study would help researchers understand the role of ultrasound as an energy source and acoustic streaming as one of the most important of ultrasound waves on intensifying gas-liquid mass transfer in a two-phase system and can be a breakthrough in the design procedure as no similar studies were found in the existing literature. Copyright © 2016. Published by Elsevier B.V.

METHOD 544. DETERMINATION OF MICROCYSTINS AND NODULARIN IN DRINKING WATER BY SOLID PHASE EXTRACTION AND LIQUID CHROMATOGRAPHY/TANDEM MASS SPECTROMETRY (LC/MS/MS)

EPA Science Inventory

Method 544 is an accurate and precise analytical method to determine six microcystins (including MC-LR) and nodularin in drinking water using solid phase extraction and liquid chromatography tandem mass spectrometry (SPE-LC/MS/MS). The advantage of this SPE-LC/MS/MS is its sensi...

Trends in long-period seismicity related to magmatic fluid compositions

USGS Publications Warehouse

Morrissey, M.M.; Chouet, B.A.

2001-01-01

Sound speeds and densities are calculated for three different types of fluids: gas-gas mixture; ash-gas mixture; and bubbly liquid. These fluid properties are used to calculate the impedance contrast (Z) and crack stiffness (C) in the fluid-driven crack model (Chouet: J. Geophys. Res., 91 (1986) 13,967; 101 (1988) 4375; A seismic model for the source of long-period events and harmonic tremor. In: Gasparini, P., Scarpa, R., Aki, K. (Eds.), Volcanic Seismology, IAVCEI Proceedings in Volcanology, Springer, Berlin, 3133). The fluid-driven crack model describes the far-field spectra of long-period (LP) events as modes of resonance of the crack. Results from our calculations demonstrate that ash-laden gas mixtures have fluid to solid density ratios comparable to, and fluid to solid velocity ratios lower than bubbly liquids (gas-volume fractions 20% gas-volume fraction yields values of Q-1r similar to those for a rectangular crack. As with gas-gas and ash-gas mixtures, an increase in mass fraction narrows the bandwidth of the dominant mode and shifts the spectra to lower frequencies. Including energy losses due to dissipative processes in a bubbly liquid increases attenuation. Attenuation may also be higher in ash-gas mixtures and foams if the effects of momentum and mass transfer between the phases were considered in the calculations. ?? 2001 Elsevier Science B. V. All rights reserved.

Decomposition behavior of hemicellulose and lignin in the step-change flow rate liquid hot water.

PubMed

Zhuang, Xinshu; Yu, Qiang; Wang, Wen; Qi, Wei; Wang, Qiong; Tan, Xuesong; Yuan, Zhenhong

2012-09-01

Hemicellulose and lignin are the main factors limiting accessibility of hydrolytic enzymes besides the crystallinity of cellulose. The decomposition behavior of hemicellulose and lignin in the step-change flow rate hot water system was investigated. Xylan removal increased from 64.53% for batch system (solid concentration 4.25% w/v, 18 min, 184°C) to 83.78% at high flow rates of 30 ml/min for 8 min, and then 10 ml/min for 10 min. Most of them (80-90%) were recovered as oligosaccharide. It was hypothesized that the flowing water could enhance the mass transfer to improve the sugars recovery. In addition, the solubilization mechanism of lignin in the liquid hot water was proposed according to the results of Fourier transform-infrared spectroscopy and scanning electron microscopy of the water-insoluble fraction and gas chromatography-mass spectrometry of the water-soluble fraction. It was proposed that lignin in the liquid hot water first migrated out of the cell wall in the form of molten bodies, and then flushed out of the reactor. A small quantity of them was further degraded into monomeric products such as vanillin, syringe aldehyde, coniferyl aldehyde, ferulic acid, and p-hydroxy-cinnamic acid. All of these observations would provide important information for the downstream processing, such as purification and concentration of sugars and the enzymatic digestion of residual solid.

Stability behaviour of antiretroviral drugs and their combinations. 5: Characterization of novel degradation products of abacavir sulfate by mass and nuclear magnetic resonance spectrometry.

PubMed

Kurmi, Moolchand; Sahu, Archana; Singh, Saranjit

2017-02-05

In the present study, degradation behaviour of abacavir sulfate was evaluated in solution and solid stress conditions. Solution state studies resulted in formation of eleven degradation products; of which two were also formed on solid stress. The same were separated by high performance liquid chromatography. They were characterized using liquid chromatography-high resolution mass spectrometry, liquid chromatography-multistage mass spectrometry and hydrogen/deuterium exchange mass spectrometry data. Additionally, seven degradation products were isolated and subjected to 1D and 2D nuclear magnetic resonance studies for their structural confirmation. Copyright © 2016 Elsevier B.V. All rights reserved.

Moon (Form-Origin)

NASA Astrophysics Data System (ADS)

Tsiapas, Elias

2016-04-01

When the Earth was formed, it was in a state of burning heat. As time went by, temperature on the planet's surface was falling due to radiation and heat transfer, and various components (crusts) began taking solid form at the Earth's poles. The formation of crusts took place at the Earth's poles, because the stirring of burning and fluid masses on the surface of the Earth was significantly slighter there than it was on the equator. Due to centrifugal force and Coriolis Effect, these solid masses headed towards the equator; those originating from the North Pole followed a south-western course, while those originating from the South Pole followed a north-western course and there they rotated from west to east at a lower speed than the underlying burning and liquid earth, because of their lower initial linear velocity, their solid state and inertia. Because inertia is proportional to mass, the initially larger solid body swept all new solid ones, incorporating them to its western side. The density of the new solid masses was higher, because the components on the surface would freeze and solidify first, before the underlying thicker components. As a result, the western side of the initial islet of solid rocks submerged, while the east side elevated. . As a result of the above, this initial islet began to spin in reverse, and after taking on the shape of a sphere, it formed the "heart" of the Moon. The Moon-sphere, rolling on the equator, would sink the solid rocks that continued to descend from the Earth's poles. The sinking rocks partially melted because of higher temperatures in the greater depths that the Moon descended to, while part of the rocks' mass bonded with the Moon and also served as a heat-insulating material, preventing the descended side of the sphere from melting. Combined with the Earth's liquid mass that covered its emerging eastern surface, new sphere-shaped shells were created, with increased density and very powerful structural cohesion. During the above mentioned process, the thick clouds surrounding Earth-Moon were causing heavy storms and on the outer surface of the rolling Moon, wherever small cavities - or pockets - existed, these would fill up with water. Then, due to the Moon's changing tilt, these pockets were sealed by sediments and as a result, small water tanks are scattered on the successive layers of the Moon, from its centre to its surface. . As this sphere (the Moon) continued to grow, the Earth-Moon system was displaying a double-planet image. The Moon's reverse rolling velocity increased according to the increase of its mass and volume. As the temperature on the surface of the Earth continued to fall, a larger number of bigger sized solid masses were descending from the poles towards the equator, and the Moon could no longer aggregate them. The gathering and interference of solid rocks of great mass acted as the catapult on which the Moon bounced off the Earth and was put into orbit around it.

Moon (Form-Origin)

NASA Astrophysics Data System (ADS)

Tsiapas, Elias; Soumelidou, Despina; Tsiapas, Christos

2017-04-01

When the Earth was formed, it was in a state of burning heat. As time went by, temperature on the planet's surface was falling due to radiation and heat transfer, and various components (crusts) began taking solid form at the Earth's poles. The formation of crusts took place at the Earth's poles, because the stirring of burning and fluid masses on the surface of the Earth was significantly slighter there than it was on the equator. Due to centrifugal force and Coriolis Effect, these solid masses headed towards the equator; those originating from the North Pole followed a south-western course, while those originating from the South Pole followed a north-western course and there they rotated from west to east at a lower speed than the underlying burning and liquid earth, because of their lower initial linear velocity, their solid state and inertia. Because inertia is proportional to mass, the initially larger solid body swept all new solid ones, incorporating them to its western side. The density of the new solid masses was higher, because the components on the surface would freeze and solidify first, before the underlying thicker components. As a result, the western side of the initial islet of solid rocks submerged, while the east side elevated. . As a result of the above, this initial islet began to spin in reverse, and after taking on the shape of a sphere, it formed the "heart" of the Moon. The Moon-sphere, rolling on the equator, would sink the solid rocks that continued to descend from the Earth's poles. The sinking rocks partially melted because of higher temperatures in the greater depths that the Moon descended to, while part of the rocks' mass bonded with the Moon and also served as a heat-insulating material, preventing the descended side of the sphere from melting. Combined with the Earth's liquid mass that covered its emerging eastern surface, new sphere-shaped shells were created, with increased density and very powerful structural cohesion. During the above mentioned process, the thick clouds surrounding Earth-Moon were causing heavy storms and on the outer surface of the rolling Moon, wherever small cavities - or pockets - existed, these would fill up with water. Then, due to the Moon's changing tilt, these pockets were sealed by sediments and as a result, small water tanks are scattered on the successive layers of the Moon, from its centre to its surface. . As this sphere (the Moon) continued to grow, the Earth-Moon system was displaying a double-planet image. The Moon's reverse rolling velocity increased according to the increase of its mass and volume. As the temperature on the surface of the Earth continued to fall, a larger number of bigger sized solid masses were descending from the poles towards the equator, and the Moon could no longer aggregate them. The gathering and interference of solid rocks of great mass acted as the catapult on which the Moon bounced off the Earth and was put into orbit around it.

Moon (Form-Origin)

NASA Astrophysics Data System (ADS)

Tsiapas, Elias

2015-04-01

When the Earth was formed, it was in a state of burning heat. As time went by, temperature on the planet's surface was falling due to radiation and heat transfer, and various components (crusts) began taking solid form at the Earth's poles. The formation of crusts took place at the Earth's poles, because the stirring of burning and fluid masses on the surface of the Earth was significantly slighter there than it was on the equator. Due to centrifugal force and Coriolis Effect, these solid masses headed towards the equator; those originating from the North Pole followed a south-western course, while those originating from the South Pole followed a north-western course and there they rotated from west to east at a lower speed than the underlying burning and liquid earth, because of their lower initial linear velocity, their solid state and inertia. Because inertia is proportional to mass, the initially larger solid body swept all new solid ones, incorporating them to its western side. The density of the new solid masses was higher, because the components on the surface would freeze and solidify first, before the underlying thicker components. As a result, the western side of the initial islet of solid rocks submerged, while the east side elevated. . As a result of the above, this initial islet began to spin in reverse, and after taking on the shape of a sphere, it formed the "heart" of the Moon. The Moon-sphere, rolling on the equator, would sink the solid rocks that continued to descend from the Earth's poles. The sinking rocks partially melted because of higher temperatures in the greater depths that the Moon descended to, while part of the rocks' mass bonded with the Moon and also served as a heat-insulating material, preventing the descended side of the sphere from melting. Combined with the Earth's liquid mass that covered its emerging eastern surface, new sphere-shaped shells were created, with increased density and very powerful structural cohesion. During the above mentioned process, the thick clouds surrounding Earth-Moon were causing heavy storms and on the outer surface of the rolling Moon, wherever small cavities - or pockets - existed, these would fill up with water. Then, due to the Moon's changing tilt, these pockets were sealed by sediments and as a result, small water tanks are scattered on the successive layers of the Moon, from its centre to its surface. . As this sphere (the Moon) continued to grow, the Earth-Moon system was displaying a double-planet image. The Moon's reverse rolling velocity increased according to the increase of its mass and volume. As the temperature on the surface of the Earth continued to fall, a larger number of bigger sized solid masses were descending from the poles towards the equator, and the Moon could no longer aggregate them. The gathering and interference of solid rocks of great mass acted as the catapult on which the Moon bounced off the Earth and was put into orbit around it.

Moon (Form-Origin)

NASA Astrophysics Data System (ADS)

Tsiapas, Elias

2014-05-01

When the Earth was formed, it was in a state of burning heat. As time went by, temperature on the planet's surface was falling due to radiation and heat transfer, and various components (crusts) began taking solid form at the Earth's poles. The formation of crusts took place at the Earth's poles, because the stirring of burning and fluid masses on the surface of the Earth was significantly slighter there than it was on the equator. Due to centrifugal force and Coriolis Effect, these solid masses headed towards the equator; those originating from the North Pole followed a south-western course, while those originating from the South Pole followed a north-western course and there they rotated from west to east at a lower speed than the underlying burning and liquid earth, because of their lower initial linear velocity, their solid state and inertia. Because inertia is proportional to mass, the initially larger solid body swept all new solid ones, incorporating them to its western side. The density of the new solid masses was higher, because the components on the surface would freeze and solidify first, before the underlying thicker components. As a result, the western side of the initial islet of solid rocks submerged, while the east side elevated. . As a result of the above, this initial islet began to spin in reverse, and after taking on the shape of a sphere, it formed the "heart" of the Moon. The Moon-sphere, rolling on the equator, would sink the solid rocks that continued to descend from the Earth's poles. The sinking rocks partially melted because of higher temperatures in the greater depths that the Moon descended to, while part of the rocks' mass bonded with the Moon and also served as a heat-insulating material, preventing the descended side of the sphere from melting. Combined with the Earth's liquid mass that covered its emerging eastern surface, new sphere-shaped shells were created, with increased density and very powerful structural cohesion. During the above mentioned process, the thick clouds surrounding Earth-Moon were causing heavy storms and on the outer surface of the rolling Moon, wherever small cavities - or pockets - existed, these would fill up with water. Then, due to the Moon's changing tilt, these pockets were sealed by sediments and as a result, small water tanks are scattered on the successive layers of the Moon, from its centre to its surface. . As this sphere (the Moon) continued to grow, the Earth-Moon system was displaying a double-planet image. The Moon's reverse rolling velocity increased according to the increase of its mass and volume. As the temperature on the surface of the Earth continued to fall, a larger number of bigger sized solid masses were descending from the poles towards the equator, and the Moon could no longer aggregate them. The gathering and interference of solid rocks of great mass acted as the catapult on which the Moon bounced off the Earth and was put into orbit around it..

Effect of Ultrasound Technology on Food and Nutritional Quality.

PubMed

Ojha, Kumari S; Tiwari, Brijesh K; O'Donnell, Colm P

2018-01-01

Ultrasound technology has been successfully demonstrated for several food processing and preservation applications. The majority of food processing applications reported refer to liquid foods. Ultrasound has been applied to solid foods in some niche applications, e.g., tenderization of meat, mass transfer applications, and drying. Similar to any other technology, ultrasound also has some positive and negative effects on food quality depending on the application and processing conditions employed. This chapter outlines various applications of ultrasound to food and its effect on food and nutritional quality. © 2018 Elsevier Inc. All rights reserved.

Estimating Residual Solids Volume In Underground Storage Tanks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Clark, Jason L.; Worthy, S. Jason; Martin, Bruce A.

2014-01-08

The Savannah River Site liquid waste system consists of multiple facilities to safely receive and store legacy radioactive waste, treat, and permanently dispose waste. The large underground storage tanks and associated equipment, known as the 'tank farms', include a complex interconnected transfer system which includes underground transfer pipelines and ancillary equipment to direct the flow of waste. The waste in the tanks is present in three forms: supernatant, sludge, and salt. The supernatant is a multi-component aqueous mixture, while sludge is a gel-like substance which consists of insoluble solids and entrapped supernatant. The waste from these tanks is retrieved andmore » treated as sludge or salt. The high level (radioactive) fraction of the waste is vitrified into a glass waste form, while the low-level waste is immobilized in a cementitious grout waste form called saltstone. Once the waste is retrieved and processed, the tanks are closed via removing the bulk of the waste, chemical cleaning, heel removal, stabilizing remaining residuals with tailored grout formulations and severing/sealing external penetrations. The comprehensive liquid waste disposition system, currently managed by Savannah River Remediation, consists of 1) safe storage and retrieval of the waste as it is prepared for permanent disposition; (2) definition of the waste processing techniques utilized to separate the high-level waste fraction/low-level waste fraction; (3) disposition of LLW in saltstone; (4) disposition of the HLW in glass; and (5) closure state of the facilities, including tanks. This paper focuses on determining the effectiveness of waste removal campaigns through monitoring the volume of residual solids in the waste tanks. Volume estimates of the residual solids are performed by creating a map of the residual solids on the waste tank bottom using video and still digital images. The map is then used to calculate the volume of solids remaining in the waste tank. The ability to accurately determine a volume is a function of the quantity and quality of the waste tank images. Currently, mapping is performed remotely with closed circuit video cameras and still photograph cameras due to the hazardous environment. There are two methods that can be used to create a solids volume map. These methods are: liquid transfer mapping / post transfer mapping and final residual solids mapping. The task is performed during a transfer because the liquid level (which is a known value determined by a level measurement device) is used as a landmark to indicate solids accumulation heights. The post transfer method is primarily utilized after the majority of waste has been removed. This method relies on video and still digital images of the waste tank after the liquid transfer is complete to obtain the relative height of solids across a waste tank in relation to known and usable landmarks within the waste tank (cooling coils, column base plates, etc.). In order to accurately monitor solids over time across various cleaning campaigns, and provide a technical basis to support final waste tank closure, a consistent methodology for volume determination has been developed and implemented at SRS.« less

Preliminary characterization of carbon dioxide transfer in a hollow fiber membrane module as a possible solution for gas-liquid transfer in microgravity conditions

NASA Astrophysics Data System (ADS)

Farges, Bérangère; Duchez, David; Dussap, Claude-Gilles; Cornet, Jean-François

2012-01-01

In microgravity, one of the major challenge encountered in biological life support systems (BLSS) is the gas-liquid transfer with, for instance, the necessity to provide CO2 (carbon source, pH control) and to recover the evolved O2 in photobioreactors used as atmosphere bioregenerative systems.This paper describes first the development of a system enabling the accurate characterization of the mass transfer limiting step for a PTFE membrane module used as a possible efficient solution to the microgravity gas-liquid transfer. This original technical apparatus, together with a technical assessment of membrane permeability to different gases, is associated with a balance model, determining thus completely the CO2 mass transfer problem between phases. First results are given and discussed for the CO2 mass transfer coefficient kLCO obtained in case of absorption experiments at pH 8 using the hollow fiber membrane module. The consistency of the proposed method, based on a gas and liquid phase balances verifying carbon conservation enables a very accurate determination of the kLCO value as a main limiting step of the whole process. Nevertheless, further experiments are still needed to demonstrate that the proposed method could serve in the future as reference method for mass transfer coefficient determination if using membrane modules for BLSS in reduced or microgravity conditions.

Temperature-difference-driven mass transfer through the vapor from a cold to a warm liquid.

PubMed

Struchtrup, Henning; Kjelstrup, Signe; Bedeaux, Dick

2012-06-01

Irreversible thermodynamics provides interface conditions that yield temperature and chemical potential jumps at phase boundaries. The interfacial jumps allow unexpected transport phenomena, such as the inverted temperature profile [Pao, Phys. Fluids 14, 306 (1971)] and mass transfer from a cold to a warm liquid driven by a temperature difference across the vapor phase [Mills and Phillips, Chem. Phys. Lett. 372, 615 (2002)]. Careful evaluation of the thermodynamic laws has shown [Bedeaux et al., Physica A 169, 263 (1990)] that the inverted temperature profile is observed for processes with a high heat of vaporization. In this paper, we show that cold to warm mass transfer through the vapor from a cold to a warm liquid is only possible when the heat of evaporation is sufficiently small. A necessary criterium for the size of the mass transfer coefficient is given.

Theoretical study of strength of elastic-plastic water-saturated interface under constrained shear

NASA Astrophysics Data System (ADS)

Dimaki, Andrey V.; Shilko, Evgeny V.; Psakhie, Sergey G.

2016-11-01

This paper presents a theoretical study of shear strength of an elastic-plastic water-filled interface between elastic permeable blocks under compression. The medium is described within the discrete element method. The relationship between the stress-strain state of the solid skeleton and pore pressure of a liquid is described in the framework of the Biot's model of poroelasticity. The simulation demonstrates that shear strength of an elastic-plastic interface depends non-linearly on the values of permeability and loading to a great extent. We have proposed an empirical relation that approximates the obtained results of the numerical simulation in assumption of the interplay of dilation of the material and mass transfer of the liquid.

The effects of intra-particle concentration gradient on consecutive adsorption-desorption of oryzanol from rice bran oil in packed-column

NASA Astrophysics Data System (ADS)

Susanti, Ari Diana; Sediawan, Wahyudi Budi; Wirawan, Sang Kompiang; Budhijanto

2017-05-01

Utilization of valuable trace components in agriculture by product such as rice bran oil is interesting to be explored. Among the valuables, oryzanol, a healthy nutrition for cardiovascular prevention, is the most promising one. Literature studies suggest that adsorption-desorption is a prospective method for oryzanol isolation. Design of commercial scale adsorption-desorption system for oryzanol needs a quantitative description of the phenomena involved. In this study, quantitative modeling of the consecutive adsorption-desorption in packed column has been proposed and verified through experimental data. The offered model takes into account the intra-particle concentration gradient in the adsorbent particle. In this model, the rate of mass transfer from the bulk of the liquid to the surface of the adsorbent particle or vice versa is expressed by film theory. The mass transfer of oryzanol from the liquid in the pore of the particle to the adjacent pore surface is assumed to be instantaneous, so solid-liquid equilibrium on the surface of the pores is always attained. For simplicity, the adsorption equilibrium model applied was coefficient distribution approach. The values of the parameters implicated in the model were obtained by curve fitting to the experimental data. It verified that the model proposed works well to quantitatively describe the consecutive adsorption-desorption of oryzanol from rice bran oil in packed column.

Impact of Heat and Mass Transfer during the Transport of Nitrogen in Coal Porous Media on Coal Mine Fires

PubMed Central

Zhou, Fubao

2014-01-01

The application of liquid nitrogen injection is an important technique in the field of coal mine fire prevention. However, the mechanism of heat and mass transfer of cryogenic nitrogen in the goaf porous medium has not been well accessed. Hence, the implementation of fire prevention engineering of liquid nitrogen roughly relied on an empirical view. According to the research gap in this respect, an experimental study on the heat and mass transfer of liquid nitrogen in coal porous media was proposed. Overall, the main mechanism of liquid nitrogen fire prevention technology in the coal mine is the creation of an inert and cryogenic atmosphere. Cryogenic nitrogen gas vapor cloud, heavier than the air, would cause the phenomenon of “gravity settling” in porous media firstly. The cryogen could be applicable to diverse types of fires, both in the openings and in the enclosures. Implementation of liquid nitrogen open-injection technique in Yangchangwan colliery achieved the goals of fire prevention and air-cooling. Meanwhile, this study can also provide an essential reference for the research on heat and mass transfer in porous media in the field of thermal physics and engineering. PMID:25054173

Impact of heat and mass transfer during the transport of nitrogen in coal porous media on coal mine fires.

PubMed

Shi, Bobo; Zhou, Fubao

2014-01-01

The application of liquid nitrogen injection is an important technique in the field of coal mine fire prevention. However, the mechanism of heat and mass transfer of cryogenic nitrogen in the goaf porous medium has not been well accessed. Hence, the implementation of fire prevention engineering of liquid nitrogen roughly relied on an empirical view. According to the research gap in this respect, an experimental study on the heat and mass transfer of liquid nitrogen in coal porous media was proposed. Overall, the main mechanism of liquid nitrogen fire prevention technology in the coal mine is the creation of an inert and cryogenic atmosphere. Cryogenic nitrogen gas vapor cloud, heavier than the air, would cause the phenomenon of "gravity settling" in porous media firstly. The cryogen could be applicable to diverse types of fires, both in the openings and in the enclosures. Implementation of liquid nitrogen open-injection technique in Yangchangwan colliery achieved the goals of fire prevention and air-cooling. Meanwhile, this study can also provide an essential reference for the research on heat and mass transfer in porous media in the field of thermal physics and engineering.

A New Approach to Determine the Density of Liquids and Solids without Measuring Mass and Volume: Introducing the "Solidensimeter"

ERIC Educational Resources Information Center

Kiriktas, Halit; Sahin, Mehmet; Eslek, Sinan; Kiriktas, Irem

2018-01-01

This study aims to design a mechanism with which the density of any solid or liquid can be determined without measuring its mass and volume in order to help students comprehend the concept of density more easily. The "solidensimeter" comprises of two scaled and nested glass containers (graduated cylinder or beaker) and sufficient water.…

The measurement of the heat-transfer coefficient between high-temperature liquids and solid surfaces

NASA Astrophysics Data System (ADS)

Utigard, T. A.; Warczok, A.; Desclaux, P.

1994-01-01

Two experimental techniques were developed for the purpose of measuring the heat-transfer coefficient between liquid slags/salts and solid surfaces. This was carried out because the heat-transfer coefficient is important for the design and operation of metallurgical reactors. A “cold-finger” technique was developed for the purpose of carrying out heat-transfer measurements during steady-state conditions simulating heat fluxes through furnace sidewalls. A lump capacitance method was developed and tested for the purpose of simulating transient conditions. To determine the effect of fluid flow on the heat-transfer coefficient, nitrogen gas stirring was used. The two techniques were tested in molten (1) and NaNO3, (2) NaCl, (3) Na3AlF6, and (4) 2FeO·SiO2, giving consistent results. It was found that the heat-transfer coefficient increases with increasing bath superheat and stirring.

Liquid Adsorption of Organic Compounds on Hematite α-Fe2O3 Using ReaxFF.

PubMed

Chia, Chung-Lim; Avendaño, Carlos; Siperstein, Flor R; Filip, Sorin

2017-10-24

ReaxFF-based molecular dynamics simulations are used in this work to study the effect of the polarity of adsorbed molecules in the liquid phase on the structure and polarization of hematite (α-Fe 2 O 3 ). We compared the adsorption of organic molecules with different polarities on a rigid hematite surface and on a flexible and polarizable surface. We show that the displacements of surface atoms and surface polarization in a flexible hematite model are proportional to the adsorbed molecule's polarity. The increase in electrostatic interactions resulting from charge transfer in the outermost solid atoms in a flexible hematite model results in better-defined adsorbed layers that are less ordered than those obtained assuming a rigid solid. These results suggest that care must be taken when parametrizing empirical transferable force fields because the calculated charges on a solid slab in vacuum may not be representative of a real system, especially when the solid is in contact with a polar liquid.

Flexible robust binder-free carbon nanotube membranes for solid state and microcapacitor application

NASA Astrophysics Data System (ADS)

Adu, Kofi; Ma, Danhao; Wang, Yuxiang; Spencer, Michael; Rajagopalan, Ramakrishnan; Wang, C.-Yu; Randall, Clive

2018-01-01

We present a liquid phase post synthesis self-assemble protocol that transforms trillions of carbon nanotubes (CNTs) in powder form into densely packed flexible, robust and binder-free macroscopic membranes with a hierarchical pore structure. We employ charge transfer engineering to spontaneously disperse the CNTs in a liquid medium. The processing protocol has limited or no impact on the intrinsic properties of the CNTs. As the thickness of the CNT membrane is increased, we observed a gradual transition from high flexibility to buckling and brittleness in the flexural properties of the membranes. The binder-free CNT membranes have bulk mass density greater than that of water (1.0 g cm-3). We correlate the mass of the CNTs in the membrane to the thickness of the membrane and obtained a bulk mass density of ˜1.11 g cm-3 ± 0.03 g cm-3. We demonstrate the use of the CNT membranes as electrode in a pristine and oxidized single/stacked solid-state capacitor as well as pristine interdigitated microcapacitor that show time constant of ˜32 ms with no degradation in performance even after 10 000 cycles. The capacitors show very good temperature dependence over a wide range of temperatures with good cycling performance up to 90 °C. The specific capacitance of the pseudocapacitive CNT electrode at room temperature was 72 F g-1 and increased to 100 F g-1 at 70 °C. The leakage current of bipolar stacked solid state capacitor was ˜100 nA cm-2 at 2.5 V when held for 72 h.

Acoustic Streaming and Heat and Mass Transfer Enhancement

NASA Technical Reports Server (NTRS)

Trinh, E. H.; Gopinath, A.

1996-01-01

A second order effect associated with high intensity sound field, acoustic streaming has been historically investigated to gain a fundamental understanding of its controlling mechanisms and to apply it to practical aspects of heat and mass transfer enhancement. The objectives of this new research project are to utilize a unique experimental technique implementing ultrasonic standing waves in closed cavities to study the details of the generation of the steady-state convective streaming flows and of their interaction with the boundary of ultrasonically levitated near-spherical solid objects. The goals are to further extend the existing theoretical studies of streaming flows and sample interactions to higher streaming Reynolds number values, for larger sample size relative to the wavelength, and for a Prandtl and Nusselt numbers parameter range characteristic of both gaseous and liquid host media. Experimental studies will be conducted in support to the theoretical developments, and the crucial impact of microgravity will be to allow the neglect of natural thermal buoyancy. The direct application to heat and mass transfer in the absence of gravity will be emphasized in order to investigate a space-based experiment, but both existing and novel ground-based scientific and technological relevance will also be pursued.

Thermodynamic analysis of Cr(VI) extraction using TOPO impregnated membranes.

PubMed

Praveen, Prashant; Loh, Kai-Chee

2016-08-15

Solid/liquid extraction of Cr(VI) was accomplished using trioctylphosphine oxide impregnated polypropylene hollow fiber membranes. Extraction of 100-500mg/L Cr(VI) by the extractant impregnated membranes (EIM) was characterized by high uptake rate and capacity, and equilibrium was attained within 45min of contact. Extraction equilibrium was pH-dependent (at an optimal pH 2), whereas stripping using 0.2M sodium hydroxide yielded the highest recovery of 98% within 60min. The distribution coefficient was independent of initial Cr(VI) concentration, and the linear distribution equilibrium isotherm could be modeled using Freundlich isotherm. The mass transfer kinetics of Cr(VI) was examined using pseudo-second-order and intraparticle diffusion models and a mass transfer mechanism was deduced. The distribution coefficient increased with temperature, which indicated endothermic nature of the reaction. Enthalpy and entropy change during Cr(VI) extraction were positive and varied in the range of 37-49kJ/mol and 114-155J/mol, respectively. The free energy change was negative, confirming the feasibility and spontaneity of the mass transfer process. Results obtained suggest that EIMs are efficient and sustainable for extraction of Cr(VI) from wastewater. Copyright © 2016 Elsevier B.V. All rights reserved.

Visualisation of gas-liquid mass transfer around a rising bubble in a quiescent liquid using an oxygen sensitive dye

NASA Astrophysics Data System (ADS)

Dietrich, Nicolas; Hebrard, Gilles

2018-02-01

An approach for visualizing and measuring the mass transfer around a single bubble rising in a quiescent liquid is reported. A colorimetric technique, developed by (Dietrich et al. Chem Eng Sci 100:172-182, 2013) using an oxygen sensitive redox dye was implemented. It was based on the reduction of the colorimetric indicator in presence of oxygen, this reduction being catalysed by sodium hydroxide and glucose. In this study, resazurin was selected because it offered various reduced forms with colours ranging from transparent (without oxygen) to pink (in presence of oxygen). These advantages made it possible to visualize the spatio-temporal oxygen mass transfer around rising bubbles. Images were recorded by a CCD camera and, after post-processing, the shape, size, and velocity of the bubbles were measured and the colours around the bubbles mapped. A calibration, linking the level of colour with the dissolved oxygen concentration, enabled colour maps to be converted into oxygen concentration fields. A rheoscopic fluid was used to visualize the wake of the bubbles. A calculation method was also developed to determine the transferred oxygen fluxes around bubbles of two sizes (d = 0.82 mm and d = 2.12 mm) and the associated liquid-side mass transfer coefficients. The results compared satisfactorily with classical global measurements made by oxygen micro-sensors or from the classical models. This study thus constitutes a striking example of how this new colorimetric method could become a remarkable tool for exploring gas-liquid mass transfer in fluids.

Visualisation of gas-liquid mass transfer around a rising bubble in a quiescent liquid using an oxygen sensitive dye

NASA Astrophysics Data System (ADS)

Dietrich, Nicolas; Hebrard, Gilles

2018-07-01

An approach for visualizing and measuring the mass transfer around a single bubble rising in a quiescent liquid is reported. A colorimetric technique, developed by (Dietrich et al. Chem Eng Sci 100:172-182, 2013) using an oxygen sensitive redox dye was implemented. It was based on the reduction of the colorimetric indicator in presence of oxygen, this reduction being catalysed by sodium hydroxide and glucose. In this study, resazurin was selected because it offered various reduced forms with colours ranging from transparent (without oxygen) to pink (in presence of oxygen). These advantages made it possible to visualize the spatio-temporal oxygen mass transfer around rising bubbles. Images were recorded by a CCD camera and, after post-processing, the shape, size, and velocity of the bubbles were measured and the colours around the bubbles mapped. A calibration, linking the level of colour with the dissolved oxygen concentration, enabled colour maps to be converted into oxygen concentration fields. A rheoscopic fluid was used to visualize the wake of the bubbles. A calculation method was also developed to determine the transferred oxygen fluxes around bubbles of two sizes (d = 0.82 mm and d = 2.12 mm) and the associated liquid-side mass transfer coefficients. The results compared satisfactorily with classical global measurements made by oxygen micro-sensors or from the classical models. This study thus constitutes a striking example of how this new colorimetric method could become a remarkable tool for exploring gas-liquid mass transfer in fluids.

[Liquid chromatography-tandem mass spectrometry method for determination of 10 macrolide antibiotics in pork samples using on-line solid phase extraction purification].

PubMed

Zhang, Xiaoguang; Liu, Dong; Liu, Hongran; Li, Qiang; Li, Lili; Wang, Lixia; Zhang, Yan

2017-10-08

A high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method based on-line solid phase extraction (SPE) purification was established to determine 10 macrolide antibiotics in pork samples. The samples were extracted with acetonitrile, and the extracts were dried with rotary evaporator at 40℃, then the analytes were dissolved with 2 mL phosphate buffer. The solutions were purified and concentrated by on-line SPE with HLB cartridges. The analytes were eluted with methanol, and then transferred to XBridge BEH C18 column, separated with the mobile phases of 10 mmol/L ammonium acetate aqueous solution and acetonitrile. Finally, the target analytes were detected by tandem mass spectrometry. The results showed that good linearity was obtained in the range of 0.1-200 μg/L for the 10 macrolide antibiotics with correlation coefficients better than 0.990. The limits of detection were in range of 0.05-0.30 μg/kg and the limits of quantitation were in range of 0.10-1.00 μg/kg. The recoveries of the method were in range of 69.6%-115.2% at the spiked levels of 0.10-10.0 μg/kg for all analytes, with the relative standard deviations less than 10%. The developed method can be used for the determination of the 10 macrolide antibiotics in pork samples.

Influence of the liquid-phase mass transfer on the performance of a packed-bed bioreactor for wastewater treatment.

PubMed

Sarti, A; Vieira, L G; Foresti, E; Zaiat, M

2001-07-01

This paper reports on the influence of the liquid-phase mass transfer on the performance of a horizontal-flow, anaerobic, immobilized-biomass (HAIB) reactor treating low-strength wastewater. The HAIB reactor was subjected to liquid superficial velocities (vs) ranging from 10 to 50 cm h(-1), corresponding to hydraulic detention time (theta h) of 10-2 h. The best performance was achieved at an overall theta h of 3.3 h due to the interdependence of biochemical reactions and mass transfer mechanisms for process optimization. The HAIB reactor was provided with four intermediate sampling ports, and the values of v(s) were fixed to permit sampling at different ports corresponding to thetah of 2 h as vs increased. The chemical oxygen demand removal (COD) efficiencies increased from 68% to 82% with the increase of v(s) from 10 to 50 cm h(-1). It could be concluded that the performance of the HAIB reactor was improved significantly by increasing vs, thus decreasing the liquid-phase mass transfer resistance.

Development of an Alternative Mixed Odor Delivery Device (MODD) for Canine Training

DTIC Science & Technology

2017-05-10

solid phase microextraction (SPME) and analysis by gas chromatography / mass spectrometry (GC/MS). Like the computational modeling, the laboratory...outlet was extracted by solid phase microextraction (SPME) and analyzed by gas chromatography with mass spectrometry (GC/MS). A polydimethylsiloxane...Menning and H. Ostmark, "Detection of liquid and homemade explosives: What do we need to know about their properties?," in Detection of Liquid

Automated processing of whole blood samples for the determination of immunosuppressants by liquid chromatography tandem-mass spectrometry.

PubMed

Vogeser, Michael; Spöhrer, Ute

2006-01-01

Liquid chromatography tandem-mass spectrometry (LC-MS/MS) is an efficient technology for routine determination of immunosuppressants in whole blood; however, time-consuming manual sample preparation remains a significant limitation of this technique. Using a commercially available robotic pipetting system (Tecan Freedom EVO), we developed an automated sample-preparation protocol for quantification of tacrolimus in whole blood by LC-MS/MS. Barcode reading, sample resuspension, transfer of whole blood aliquots into a deep-well plate, addition of internal standard solution, mixing, and protein precipitation by addition of an organic solvent is performed by the robotic system. After centrifugation of the plate, the deproteinized supernatants are submitted to on-line solid phase extraction, using column switching prior to LC-MS/MS analysis. The only manual actions within the entire process are decapping of the tubes, and transfer of the deep-well plate from the robotic system to a centrifuge and finally to the HPLC autosampler. Whole blood pools were used to assess the reproducibility of the entire analytical system for measuring tacrolimus concentrations. A total coefficient of variation of 1.7% was found for the entire automated analytical process (n=40; mean tacrolimus concentration, 5.3 microg/L). Close agreement between tacrolimus results obtained after manual and automated sample preparation was observed. The analytical system described here, comprising automated protein precipitation, on-line solid phase extraction and LC-MS/MS analysis, is convenient and precise, and minimizes hands-on time and the risk of mistakes in the quantification of whole blood immunosuppressant concentrations compared to conventional methods.

EPA Method 8321B (SW-846): Solvent-Extractable Nonvolatile Compounds by High Performance Liquid Chromatography-Thermospray-Mass Spectrometry (HPLC-TS-MS) or Ultraviolet (UV) Detection

EPA Pesticide Factsheets

Method 8321B describes procedures for preparation and analysis of solid, aqueous liquid, drinking water and wipe samples using high performance liquid chromatography and mass spectrometry for extractable non-volatile compounds.

Biogas production from the mechanically pretreated, liquid fraction of sorted organic municipal solid wastes.

PubMed

Alvarado-Lassman, A; Méndez-Contreras, J M; Martínez-Sibaja, A; Rosas-Mendoza, E S; Vallejo-Cantú, N A

2017-06-01

The high liquid content in fruit and vegetable wastes makes it convenient to mechanically separate these wastes into mostly liquid and solid fractions by means of pretreatment. Then, the liquid fraction can be treated using a high-rate anaerobic biofilm reactor to produce biogas, simultaneously reducing the amount of solids that must be landfilled. In this work, the specific composition of municipal solid waste (MSW) in a public market was determined; then, the sorted organic fraction of municipal solid waste was treated mechanically to separate and characterize the mostly liquid and solid fractions. Then, the mesophilic anaerobic digestion for biogas production of the first fraction was evaluated. The anaerobic digestion resulted in a reduced hydraulic retention time of two days with high removal of chemical oxygen demand, that is, 88% on average, with the additional benefit of reducing the mass of the solids that had to be landfilled by about 80%.

Modelling of intermittent microwave convective drying: parameter sensitivity

NASA Astrophysics Data System (ADS)

Zhang, Zhijun; Qin, Wenchao; Shi, Bin; Gao, Jingxin; Zhang, Shiwei

2017-06-01

The reliability of the predictions of a mathematical model is a prerequisite to its utilization. A multiphase porous media model of intermittent microwave convective drying is developed based on the literature. The model considers the liquid water, gas and solid matrix inside of food. The model is simulated by COMSOL software. Its sensitivity parameter is analysed by changing the parameter values by ±20%, with the exception of several parameters. The sensitivity analysis of the process of the microwave power level shows that each parameter: ambient temperature, effective gas diffusivity, and evaporation rate constant, has significant effects on the process. However, the surface mass, heat transfer coefficient, relative and intrinsic permeability of the gas, and capillary diffusivity of water do not have a considerable effect. The evaporation rate constant has minimal parameter sensitivity with a ±20% value change, until it is changed 10-fold. In all results, the temperature and vapour pressure curves show the same trends as the moisture content curve. However, the water saturation at the medium surface and in the centre show different results. Vapour transfer is the major mass transfer phenomenon that affects the drying process.

Effect of particle momentum transfer on an oblique-shock-wave/laminar-boundary-layer interaction

NASA Astrophysics Data System (ADS)

Teh, E.-J.; Johansen, C. T.

2016-11-01

Numerical simulations of solid particles seeded into a supersonic flow containing an oblique shock wave reflection were performed. The momentum transfer mechanism between solid and gas phases in the shock-wave/boundary-layer interaction was studied by varying the particle size and mass loading. It was discovered that solid particles were capable of significant modulation of the flow field, including suppression of flow separation. The particle size controlled the rate of momentum transfer while the particle mass loading controlled the magnitude of momentum transfer. The seeding of micro- and nano-sized particles upstream of a supersonic/hypersonic air-breathing propulsion system is proposed as a flow control concept.

Kinetic Release of Alkalinity from Particle-Containing Oil-in-Water Emulsions

NASA Astrophysics Data System (ADS)

Muller, K.; Chapra, S. C.; Ramsburg, A.

2014-12-01

Oil-in-water emulsions are typically employed during remediation to promote biotic reduction of contaminants. Emulsions, however, hold promise for encapsulated delivery of many types of active ingredients required for successful site remediation or long-term site stewardship. Our research is currently focused on using alkalinity-containing particles held within oil-in-water emulsions to sustain control of subsurface pH. Here we describe results from laboratory experiments and mathematical modeling conducted to quantify the kinetics associated with the emulsion delivery and alkalinity release process. Kinetically stable oil-in-water emulsions containing (~60 nmCaCO3 or ~100 nm MgO particles) were previously developed using soybean oil and Gum Arabic as a stabilizing agent. Batch and column experiments were employed to assess the accessibility and release of the alkalinity from the emulsion. Successive additions of HCl were used in batch systems to produce several pH responses (pH rebounds) that were subsequently modeled to elucidate release mechanisms and rates for varying emulsion compositions and particle types. Initial results suggest that a linear-driving-force model is generally able to capture the release behavior in the batch system when the temporally-constant, lumped mass-transfer coefficient is scaled by the fraction of particle mass remaining within the droplets. This result suggests that the rate limiting step in the release process may be the interphase transfer of reactive species at the oil-water interface. 1-d column experiments were also completed in order to quantify the extent and rate of alkalinity release from emulsion droplets retained in a sandy medium. Alkalinity release from the retained droplets treated a pH 4 influent water for 25-60 pore volumes (the duration depended on particle type and mass loading), and the cessation in treatment corresponded to exhaustion of the particle mass held within the oil. Column experiments were simulated using a transport code containing the linear-driving-force expression evaluated in the batch experiments. In these simulations the lumped mass transfer coefficient was fit and compared with values predicted using existing correlations for liquid-liquid and solid-liquid interfaces in porous media.

Local mass and energy transports in evaporation processes from a vapor-liquid interface in a slit pore based on molecular dynamics

NASA Astrophysics Data System (ADS)

Fujiwara, K.; Shibahara, M.

2018-02-01

Molecular evaporation processes from a vapor-liquid interface formed in a slit-like pore were examined based on the classical molecular dynamics method, in order to elucidate a molecular mechanism of local mass and energy transports in a slit. The calculation system consisted of monatomic molecules and atoms which interact through the 12-6 Lennard-Jones potential. At first, a liquid was situated in a slit with a vapor-liquid interface, and instantaneous amounts of the mass and energy fluxes defined locally in the slit were obtained in two dimensions to reveal local fluctuation properties of the fluid in equilibrium states. Then, imposing a temperature gradient in the calculation system, non-equilibrium evaporation processes in the slit were investigated in details based on the local mass and energy fluxes. In this study, we focused on the fluid which is in the vicinity of the solid surface and in contact with the vapor phase. In the non-equilibrium evaporation processes, the results revealed that the local energy transport mechanism in the vicinity of the solid surface is different from that of the vapor phase, especially in the case of the relatively strong fluid-solid interaction. The results also revealed that the local mass transport in the vicinity of the solid surface can be interpreted based on the mechanism of the local energy transport, and the mechanism provides valuable information about pictures of the evaporation phenomena especially in the vicinity of the hydrophilic surfaces. It suggests that evaluating and changing this mechanism of the local energy transport are necessary to control the local mass flux more precisely in the vicinity of the solid surface.

Modeling of Blast Furnace with Layered Cohesive Zone

NASA Astrophysics Data System (ADS)

Dong, X. F.; Yu, A. B.; Chew, S. J.; Zulli, P.

2010-04-01

An ironmaking blast furnace (BF) is a moving bed reactor involving counter-, co-, and cross-current flows of gas, powder, liquids, and solids, coupled with heat exchange and chemical reactions. The behavior of multiple phases directly affects the stability and productivity of the furnace. In the present study, a mathematical model is proposed to describe the behavior of fluid flow, heat and mass transfer, as well as chemical reactions in a BF, in which gas, solid, and liquid phases affect each other through interaction forces, and their flows are competing for the space available. Process variables that characterize the internal furnace state, such as reduction degree, reducing gas and burden concentrations, as well as gas and condensed phase temperatures, have been described quantitatively. In particular, different treatments of the cohesive zone (CZ), i.e., layered, isotropic, and anisotropic nonlayered, are discussed, and their influence on simulation results is compared. The results show that predicted fluid flow and thermochemical phenomena within and around the CZ and in the lower part of the BF are different for different treatments. The layered CZ treatment corresponds to the layered charging of burden and naturally can predict the CZ as a gas distributor and liquid generator.

TANK 32 EVAPORATOR FEED PUMP TRANSFER ANALYSIS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tamburello, D; Richard Dimenna, R; Si Lee, S

2009-01-27

The transfer of liquid salt solution from Tank 32 to an evaporator is to be accomplished by activating the evaporator feed pump, with the supernate surface at a minimum height of approximately 74.4 inches above the sludge layer, while simultaneously turning on the downcomer with a flow rate of 110 gpm. Previously, activation of the evaporator feed pump was an isolated event without any other components running at the same time. An analysis of the dissolved solution transfer has been performed using computational fluid dynamics (CFD) methods to determine the amount of entrained sludge solids pumped out of the tankmore » toward the evaporator with the downcomer turned on. The analysis results shows that, for the minimum tank liquid level of 105 inches above the tank bottom (which corresponds to a liquid depth of 74.4 inches above the sludge layer), the evaporator feed pump will contain less than 0.1 wt% sludge solids in the discharge stream, which is an order of magnitude less than the 1.0 wt% undissolved solids (UDS) loading criteria to feed the evaporator. Lower liquid levels with respect to the sludge layer will result in higher amounts of sludge entrainment due to the increased plunging jet velocity from the downcomer disturbing the sludge layer.« less

The effect of the liquid-solid system properties on the interline heat transfer coefficient

NASA Technical Reports Server (NTRS)

Wayner, P. C., Jr.

1977-01-01

A theoretical procedure to determine the heat transfer characteristics of the interline region of an evaporating meniscus using the macroscopic optical and thermophysical properties of the system is outlined. The analysis is based on the premise that the interline transport processes are controlled by the London-van der Waals forces between condensed phases (solid and liquid). The procedure is used to compare the relative size of the interline heat sink of various systems using a constant heat flux model. This solution demonstrates the importance of the interline heat flow number which is evaluated for various systems. The heat transfer characteristics of the decane-steel system are numerically compared with those of the carbon tetrachloride-quartz system.

Effect of sludge features and extraction-esterification technology on the synthesis of biodiesel from secondary wastewater treatment sludges.

PubMed

Patiño, Yolanda; Mantecón, Laura G; Polo, Sara; Faba, Laura; Díaz, Eva; Ordóñez, Salvador

2018-01-01

Secondary sludge from municipal wastewater treatment plant is proposed as a promising alternative lipid feedstock for biodiesel production. A deep study combining different type of raw materials (sludge coming from the oxic, anoxic and anaerobic steps of the biological treatment) with different technologies (liquid-liquid and solid-liquid extractions followed by acid catalysed transesterification and in situ extraction-transesterification procedure) allows a complete comparison of available technologies. Different parameters - contact time, catalyst concentration, pretreatments - were considered, obtaining more than 17% FAMEs yield after 50min of sonication with the in situ procedure and 5% of H 2 SO 4 . This result corresponds to an increment of more than 65% respect to the best results reported at typical conditions. Experimental data were used to propose a mathematical model for this process, demonstrating that the mass transfer of lipids from the sludge to the liquid is the limiting step. Copyright © 2017 Elsevier Ltd. All rights reserved.

Solid Hydrogen Experiments for Atomic Propellants: Image Analyses

NASA Technical Reports Server (NTRS)

Palaszewski, Bryan

2002-01-01

This paper presents the results of detailed analyses of the images from experiments that were conducted on the formation of solid hydrogen particles in liquid helium. Solid particles of hydrogen were frozen in liquid helium, and observed with a video camera. The solid hydrogen particle sizes, their agglomerates, and the total mass of hydrogen particles were estimated. Particle sizes of 1.9 to 8 mm (0.075 to 0.315 in.) were measured. The particle agglomerate sizes and areas were measured, and the total mass of solid hydrogen was computed. A total mass of from 0.22 to 7.9 grams of hydrogen was frozen. Compaction and expansion of the agglomerate implied that the particles remain independent particles, and can be separated and controlled. These experiment image analyses are one of the first steps toward visually characterizing these particles, and allow designers to understand what issues must be addressed in atomic propellant feed system designs for future aerospace vehicles.

Quantitative characterization of solid epoxy resins using comprehensive two dimensional liquid chromatography coupled with electrospray ionization-time of flight mass spectrometry.

PubMed

Julka, Samir; Cortes, Hernan; Harfmann, Robert; Bell, Bruce; Schweizer-Theobaldt, Andreas; Pursch, Matthias; Mondello, Luigi; Maynard, Shawn; West, David

2009-06-01

A comprehensive multidimensional liquid chromatography system coupled to Electrospray Ionization-Mass Spectrometry (LCxLC-ESI-MS) was developed for detailed characterization and quantitation of solid epoxy resin components. The two orthogonal modes of separation selected were size exclusion chromatography (SEC) in the first dimension and liquid chromatography at critical conditions (LCCC) in the second dimension. Different components present in the solid epoxy resins were separated and quantitated for the first time based on the functional groups and molecular weight heterogeneity. Coupling LCxLC separations with mass spectrometry enabled the identification of components resolved in the two-dimensional space. Several different functional group families of compounds were separated and identified, including epoxy-epoxy and epoxy-alpha-glycol functional oligomers, and their individual molecular weight ranges were determined. Repeatability obtained ranged from 0.5% for the main product to 21% for oligomers at the 0.4% concentration level.

Simultaneous determination of phenolic compounds in Equisetum palustre L. by ultra high performance liquid chromatography with tandem mass spectrometry combined with matrix solid-phase dispersion extraction.

PubMed

Wei, Zuofu; Pan, Youzhi; Li, Lu; Huang, Yuyang; Qi, Xiaolin; Luo, Meng; Zu, Yuangang; Fu, Yujie

2014-11-01

A method based on matrix solid-phase dispersion extraction followed by ultra high performance liquid chromatography with tandem mass spectrometry is presented for the extraction and determination of phenolic compounds in Equisetum palustre. This method combines the high efficiency of matrix solid-phase dispersion extraction and the rapidity, sensitivity, and accuracy of ultra high performance liquid chromatography with tandem mass spectrometry. The influential parameters of the matrix solid-phase dispersion extraction were investigated and optimized. The optimized conditions were as follows: silica gel was selected as dispersing sorbent, the ratio of silica gel to sample was selected to be 2:1 (400/200 mg), and 8 mL of 80% methanol was used as elution solvent. Furthermore, a fast and sensitive ultra high performance liquid chromatography with tandem mass spectrometry method was developed for the determination of nine phenolic compounds in E. palustre. This method was carried out within <6 min, and exhibited satisfactory linearity, precision, and recovery. Compared with ultrasound-assisted extraction, the proposed matrix solid-phase dispersion procedure possessed higher extraction efficiency, and was more convenient and time saving with reduced requirements on sample and solvent amounts. All these results suggest that the developed method represents an excellent alternative for the extraction and determination of active components in plant matrices. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Global volatile profile of virgin olive oils flavoured by aromatic/medicinal plants.

PubMed

Perestrelo, R; Silva, C; Silva, P; Câmara, J S

2017-07-15

The global volatile profile of commercial virgin olive oils and flavoured olive oils with aromatic/medicinal plants, was established using liquid-liquid microextraction (LLME) and headspace solid-phase microextraction (HS-SPME) combined with gas chromatography-quadrupole mass spectrometry (GC-qMS). More than 60 volatile organic compounds (VOCs belonging to different groups were identified using both methods. Olive oils volatile profile was slightly influenced by maceration process, which occurred at room temperature (20±2°C) for 15days. The predominant differences were observed in terpenoids group, since some of them were only identified in the flavoured olive oils, while others showed an increase with the maceration process. VOCs mass transfer from plants to olive oils could explain the observed results. Principal components analysis (PCA) applied to LLME/GC-qMS data allowed to distinguish the olive oils. The flavoured oils would increase the use of olive oil among consumers as consequence of the improvement of its aromatic profile and healthy properties. Copyright © 2017 Elsevier Ltd. All rights reserved.

On the importance of the heat and mass transfer resistances in internally-cooled liquid desiccant dehumidifiers and regenerators

DOE PAGES

Woods, Jason; Kozubal, Eric

2018-02-06

Liquid desiccant heat and mass exchangers are a promising technology for efficient humidity control in buildings. Many researchers have investigated these exchangers, often using numerical models to predict their performance. However, there is a lack of information in the literature on the magnitude of the heat and mass transfer resistances, both for the dehumidifier (which absorbs moisture from the air) and the regenerator (which heats the liquid desiccant to re-concentrate it). This article focuses on internally-cooled, 3-fluid exchangers in a parallel plate geometry. Water heats or cools a desiccant across a plate, and the desiccant absorbs or releases water intomore » an airstream through a membrane. A sensitivity analysis was used to estimate the importance of each of the heat and mass transfer resistances (air, membrane, desiccant, plate, water), and how it changes with different design geometries. The results show that, for most designs, the latent and sensible heat transfer of the dehumidifier is dominated by the air mass transfer resistance and air heat transfer resistance, respectively. The air mass transfer resistance is also important for the regenerator, but much less so; the change in the desiccant equilibrium humidity ratio due to a change in either temperature or desiccant mass fraction is much higher at the regenerator's higher temperatures. This increases the importance of (1) getting heat from the water to the desiccant/membrane interface, and (2) diffusing salt ions quickly away from the desiccant/membrane interface. The membrane heat transfer and water heat transfer resistances were found to be the least important. These results can help inform decisions about what simplifying assumptions to make in numerical models, and can also help in designing these exchangers by understanding which resistances are most important.« less

On the importance of the heat and mass transfer resistances in internally-cooled liquid desiccant dehumidifiers and regenerators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Woods, Jason; Kozubal, Eric

Liquid desiccant heat and mass exchangers are a promising technology for efficient humidity control in buildings. Many researchers have investigated these exchangers, often using numerical models to predict their performance. However, there is a lack of information in the literature on the magnitude of the heat and mass transfer resistances, both for the dehumidifier (which absorbs moisture from the air) and the regenerator (which heats the liquid desiccant to re-concentrate it). This article focuses on internally-cooled, 3-fluid exchangers in a parallel plate geometry. Water heats or cools a desiccant across a plate, and the desiccant absorbs or releases water intomore » an airstream through a membrane. A sensitivity analysis was used to estimate the importance of each of the heat and mass transfer resistances (air, membrane, desiccant, plate, water), and how it changes with different design geometries. The results show that, for most designs, the latent and sensible heat transfer of the dehumidifier is dominated by the air mass transfer resistance and air heat transfer resistance, respectively. The air mass transfer resistance is also important for the regenerator, but much less so; the change in the desiccant equilibrium humidity ratio due to a change in either temperature or desiccant mass fraction is much higher at the regenerator's higher temperatures. This increases the importance of (1) getting heat from the water to the desiccant/membrane interface, and (2) diffusing salt ions quickly away from the desiccant/membrane interface. The membrane heat transfer and water heat transfer resistances were found to be the least important. These results can help inform decisions about what simplifying assumptions to make in numerical models, and can also help in designing these exchangers by understanding which resistances are most important.« less

Fundamental Researches on the High-speed and High-efficiency Steelmaking Reaction

NASA Astrophysics Data System (ADS)

Kitamura, Shin-ya; Shibata, Hiroyuki; Maruoka, Nobuhiro

2012-06-01

Traditionally, steelmaking reactions have been analyzed by thermodynamics. Recently, software packages that can be used to calculate the equilibrium conditions have improved greatly. In some cases, information obtained in this software is useful for analyzing the steelmaking reaction. On the other hand, in industrial operation, steelmaking reactions, i.e., decarburization, dephosphorization, desulfurization or nitrogen removal, do not reach the equilibrium condition. Therefore, the kinetic model is very important for gaining a theoretical understanding of the steelmaking reaction. In this paper, the following recent research activities were shown; 1) mass transfer of impurities between solid oxide and liquid slag, 2) simulation model of hot metal dephosphorization by multiphase slag, 3) evaluation of reaction rate at bath surface in gas-liquid reaction system and 4) condition for forming of metal emulsion by bottom bubbling.

Miniature Distillation Column for Producing LOX From Air

NASA Technical Reports Server (NTRS)

Rozzi, Jay C.

2006-01-01

The figure shows components of a distillation column intended for use as part of a system that produces high-purity liquid oxygen (LOX) from air by distillation. (The column could be easily modified to produce high-purity liquid nitrogen.) Whereas typical industrial distillation columns for producing high-purity liquid oxygen and/or nitrogen are hundreds of feet tall, this distillation column is less than 3 ft (less than about 0.9 m) tall. This column was developed to trickle-charge a LOX-based emergency oxygen system (EOS) for a large commercial aircraft. A description of the industrial production of liquid oxygen and liquid nitrogen by distillation is prerequisite to a meaningful description of the present miniaturized distillation column. Typically, such industrial production takes place in a chemical processing plant in which large quantities of high-pressure air are expanded in a turboexpander to (1) recover a portion of the electrical power required to compress the air and (2) partially liquefy the air. The resulting two-phase flow of air is sent to the middle of a distillation column. The liquid phase is oxygen-rich, and its oxygen purity increases as it flows down the column. The vapor phase is nitrogen-rich and its nitrogen purity increases as it flows up the column. A heater or heat exchanger, commonly denoted a reboiler, is at the bottom of the column. The reboiler is so named because its role is to reboil some of the liquid oxygen collected at the bottom of the column to provide a flow of oxygen-rich vapor. As the oxygen-rich vapor flows up the column, it absorbs the nitrogen in the down-flowing liquid by mass transfer. Once the vapor leaves the lower portion of the column, it interacts with down-flowing nitrogen liquid that has been condensed in a heat exchanger, commonly denoted a condenser, at the top of the column. Liquid oxygen and liquid nitrogen products are obtained by draining some of the purified product at the bottom and top of the column, respectively. Because distillation is a mass-transfer process, the purity of the product(s) can be increased by increasing the effectiveness of the mass-transfer process (increasing the mass-transfer coefficient) and/or by increasing the available surface area for mass transfer through increased column height. The diameter of a distillation column is fixed by pressure-drop and mass-flow requirements. The approach taken in designing the present distillation column to be short yet capable of yielding a product of acceptably high purity was to pay careful attention to design details that affect mass-transfer processes.

Assessment of external heat transfer coefficient during oocyte vitrification in liquid and slush nitrogen using numerical simulations to determine cooling rates.

PubMed

Santos, M V; Sansinena, M; Zaritzky, N; Chirife, J

2012-01-01

In oocyte vitrification, plunging directly into liquid nitrogen favor film boiling and strong nitrogen vaporization. A survey of literature values of heat transfer coefficients (h) for film boiling of small metal objects with different geometries plunged in liquid nitrogen revealed values between 125 to 1000 W per per square m per K. These h values were used in a numerical simulation of cooling rates of two oocyte vitrification devices (open-pulled straw and Cryotop), plunged in liquid and slush nitrogen conditions. Heat conduction equation with convective boundary condition was considered a linear mathematical problem and was solved using the finite element method applying the variational formulation. COMSOL Multiphysics was used to simulate the cooling process of the systems. Predicted cooling rates for OPS and Cryotop when cooled at -196 degree C (liquid nitrogen) or -207 degree C (average for slush nitrogen) for heat transfer coefficients estimated to be representative of film boiling, indicated lowering the cooling temperature produces only a maximum 10 percent increase in cooling rates; confirming the main benefit of plunging in slush over liquid nitrogen does not arise from their temperature difference. Numerical simulations also demonstrated that a hypothetical four-fold increase in the cooling rate of vitrification devices when plunging in slush nitrogen would be explained by an increase in heat transfer coefficient. This improvement in heat transfer (i.e., high cooling rates) in slush nitrogen is attributed to less or null film boiling when a sample is placed in slush (mixture of liquid and solid nitrogen) because it first melts the solid nitrogen before causing the liquid to boil and form a film.

The simultaneous mass and energy evaporation (SM2E) model.

PubMed

Choudhary, Rehan; Klauda, Jeffery B

2016-01-01

In this article, the Simultaneous Mass and Energy Evaporation (SM2E) model is presented. The SM2E model is based on theoretical models for mass and energy transfer. The theoretical models systematically under or over predicted at various flow conditions: laminar, transition, and turbulent. These models were harmonized with experimental measurements to eliminate systematic under or over predictions; a total of 113 measured evaporation rates were used. The SM2E model can be used to estimate evaporation rates for pure liquids as well as liquid mixtures at laminar, transition, and turbulent flow conditions. However, due to limited availability of evaporation data, the model has so far only been tested against data for pure liquids and binary mixtures. The model can take evaporative cooling into account and when the temperature of the evaporating liquid or liquid mixture is known (e.g., isothermal evaporation), the SM2E model reduces to a mass transfer-only model.

Laboratory evaluation of thermal protective clothing performance upon hot liquid splash.

PubMed

Gholamreza, Farzan; Song, Guowen

2013-07-01

This study provides an understanding of heat and mass transfer through materials exposed to hot liquid splash, a relatively unexplored hazard in the safety clothing industry. Selected fabrics and layered systems were exposed to three hot liquids to study the effects of hot liquids and configuration. To explore the energy transfer mechanisms, a modified apparatus (based on ASTM F 2701-08) was developed to assess the protection performance provided by a fabric when exposed to a hot liquid. The modified test method allows measurement of the energy absorbed by the sensor, and with the use of a skin model, the time required to produce a second-degree burn injury was predicted. The preliminary testing demonstrated that mass transfer of the hot liquid through the fabric is the main factor contributing to burn injury. Key factors that determine the level of protection that a fabric system provides are summarized.

Analysis of lignans in Magnoliae Flos by turbulent flow chromatography with online solid-phase extraction and high-performance liquid chromatography with tandem mass spectrometry.

PubMed

Zhou, Xuan; Chen, Cen; Ye, Xiaolan; Song, Fenyun; Fan, Guorong; Wu, Fuhai

2016-04-01

In this study, a method coupling turbulent flow chromatography with online solid-phase extraction and high-performance liquid chromatography with tandem mass spectrometry was developed for analyzing the lignans in Magnoliae Flos. By the online pretreatment of turbulent flow chromatography solid-phase extraction, the impurities removal and analytes concentration were automatically processed, and the lignans were separated rapidly and well. Seven lignans of Magnoliae Flos including epieudesmin, magnolin, 1-irioresinol-B-dimethyl ether, epi-magnolin, fargesin aschantin, and demethoxyaschantin were identified by comparing their retention behavior, UV spectra, and mass spectra with those of reference substances or literature data. The developed method was validated, and the good results showed that the method was not only automatic and rapid, but also accurate and reliable. The turbulent flow chromatography with online solid-phase extraction and high-performance liquid chromatography with tandem mass spectrometry method holds a high potential to become an effective method for the quality control of lignans in Magnoliae Flos and a useful tool for the analysis of other complex mixtures. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

[Influence of liquid or solid culture conditions on the volatile components of mycelia of Isariacateinannulata].

PubMed

Zhang, Delong; Wang, Xiaodong; Lu, Ruili; Li, Kangle; Hu, Fenglin

2011-12-01

To determine the volatile components of mycelia of Isaria cateinannulata cultured under different culture conditions, and to analyze the relationships between the culture conditions and volatile metabolites. Mycelia were cultured in solid plates with SDAY medium and liquid shake flasks with SDY medium. The culture conditions were at 25 degrees C and 8 days. Volatile components in the mycelia of I. cateinannulata were extracted with simultaneous distillation extraction and analyzed by gas chromatography-mass spectrometry. Alkenes, alkanes, heterocyclic and polycyclic aromatic hydrocarbons (PAH) were existed abundantly both in the mycelia of liquid and solid cultures, but the kinds and relative concentrations of the volatile components in mycelia of liquid and solid cultures were very different. Forty-one compounds were identified from the mycelia of solid culture and 32 compounds were identified from the mycelia of liquid culture. Esters, quinones and oximes were only found in solid cultured mycelia whereas carboxylic acids were only discovered in the mycelia of liquid culture. At the same time, mycelia of liquid culture contained much more phenols. The most abundant compounds in mycelia of liquid and solid cultures were hydrocarbons. The volatile extracts of solid cultured mycelia contained 57.6% alkenes and 9.19% alkanes. The volatile extracts of liquid cultured mycelia contained 7.85% alkenes and 22.4% alkanes. Liquid or solid culture conditions influenced the volatile components of mycelia of I. cateinannulata.

Determination of local values of gas and liquid mass flux in highly loaded two-phase flow

NASA Technical Reports Server (NTRS)

Burick, R. J.; Scheuerman, C. H.; Falk, A. Y.

1974-01-01

A measurement system using a deceleration probe was designed for determining the local values of gas and liquid mass flux in various gas/liquid droplet sprayfields. The system was used to characterize two-phase flowfields generated by gas/liquid rocket-motor injectors. Measurements were made at static pressures up to 500 psia and injected mass flow ratios up to 20. The measurement system can also be used at higher pressures and in gas/solid flowfields.

Engineering: Liquid metal pumped at a record temperature

NASA Astrophysics Data System (ADS)

Lambrinou, Konstantina

2017-10-01

Although liquid metals are effective fluids for heat transfer, pumping them at high temperatures is limited by their corrosiveness to solid metals. A clever pump design addresses this challenge using only ceramics. See Article p.199

Optimization of reaction conditions for the electroleaching of manganese from low-grade pyrolusite

NASA Astrophysics Data System (ADS)

Zhang, Xing-ran; Liu, Zuo-hua; Fan, Xing; Lian, Xin; Tao, Chang-yuan

2015-11-01

In the present study, a response surface methodology was used to optimize the electroleaching of Mn from low-grade pyrolusite. Ferrous sulfate heptahydrate was used in this reaction as a reducing agent in sulfuric acid solutions. The effect of six process variables, including the mass ratio of ferrous sulfate heptahydrate to pyrolusite, mass ratio of sulfuric acid to pyrolusite, liquid-to-solid ratio, current density, leaching temperature, and leaching time, as well as their binary interactions, were modeled. The results revealed that the order of these factors with respect to their effects on the leaching efficiency were mass ratio of ferrous sulfate heptahydrate to pyrolusite > leaching time > mass ratio of sulfuric acid to pyrolusite > liquid-to-solid ratio > leaching temperature > current density. The optimum conditions were as follows: 1.10:1 mass ratio of ferrous sulfate heptahydrate to pyrolusite, 0.9:1 mass ratio of sulfuric acid to pyrolusite, liquid-to-solid ratio of 0.7:1, current density of 947 A/m2, leaching time of 180 min, and leaching temperature of 73°C. Under these conditions, the predicted leaching efficiency for Mn was 94.1%; the obtained experimental result was 95.7%, which confirmed the validity of the model.

Molecular dynamics study of solid-liquid heat transfer and passive liquid flow

NASA Astrophysics Data System (ADS)

Yesudasan Daisy, Sumith

High heat flux removal is a challenging problem in boilers, electronics cooling, concentrated photovoltaic and other power conversion devices. Heat transfer by phase change is one of the most efficient mechanisms for removing heat from a solid surface. Futuristic electronic devices are expected to generate more than 1000 W/cm2 of heat. Despite the advancements in microscale and nanoscale manufacturing, the maximum passive heat flux removal has been 300 W/cm2 in pool boiling. Such limitations can be overcome by developing nanoscale thin-film evaporation based devices, which however require a better understanding of surface interactions and liquid vapor phase change process. Evaporation based passive flow is an inspiration from the transpiration process that happens in trees. If we can mimic this process and develop heat removal devices, then we can develop efficient cooling devices. The existing passive flow based cooling devices still needs improvement to meet the future demands. To improve the efficiency and capacity of these devices, we need to explore and quantify the passive flow happening at nanoscales. Experimental techniques have not advanced enough to study these fundamental phenomena at the nanoscale, an alternative method is to perform theoretical study at nanoscales. Molecular dynamics (MD) simulation is a widely accepted powerful tool for studying a range of fundamental and engineering problems. MD simulations can be utilized to study the passive flow mechanism and heat transfer due to it. To study passive flow using MD, apart from the conventional methods available in MD, we need to have methods to simulate the heat transfer between solid and liquid, local pressure, surface tension, density, temperature calculation methods, realistic boundary conditions, etc. Heat transfer between solid and fluids has been a challenging area in MD simulations, and has only been minimally explored (especially for a practical fluid like water). Conventionally, an equilibrium canonical ensemble (NVT) is simulated using thermostat algorithms. For research in heat transfer involving solid liquid interaction, we need to perform non equilibrium MD (NEMD) simulations. In such NEMD simulations, the methods used for simulating heating from a surface is very important and must capture proper physics and thermodynamic properties. Development of MD simulation techniques to simulate solid-liquid heating and the study of fundamental mechanism of passive flow is the main focus of this thesis. An accurate surface-heating algorithm was developed for water which can now allow the study of a whole new set of fundamental heat transfer problems at the nanoscale like surface heating/cooling of droplets, thin-films, etc. The developed algorithm is implemented in the in-house developed C++ MD code. A direct two dimensional local pressure estimation algorithm is also formulated and implemented in the code. With this algorithm, local pressure of argon and platinum interaction is studied. Also, the surface tension of platinum-argon (solid-liquid) was estimated directly from the MD simulations for the first time. Contact angle estimation studies of water on platinum, and argon on platinum were also performed. A thin film of argon is kept above platinum plate and heated in the middle region, leading to the evaporation and pressure reduction thus creating a strong passive flow in the near surface region. This observed passive liquid flow is characterized by estimating the pressure, density, velocity and surface tension using Eulerian mapping method. Using these simulation, we have demonstrated the fundamental nature and origin of surface-driven passive flow. Heat flux removed from the surface is also estimated from the results, which shows a significant improvement can be achieved in thermal management of electronic devices by taking advantage of surface-driven strong passive liquid flow. Further, the local pressure of water on silicon di-oxide surface is estimated using the LAMMPS atomic to continuum (ATC) package towards the goal of simulating the passive flow in water.

Measurement of the oxygen mass transfer through the air-water interface.

PubMed

Mölder, Erik; Mashirin, Alelxei; Tenno, Toomas

2005-01-01

Gas mass transfer through the liquid-gas interface has enormous importance in various natural and industrial processes. Surfactants or insoluble compounds adsorbed onto an interface will inhibit the gas mass transfer through the liquid-gas surface. This study presents a technique for measuring the oxygen mass transfer through the air-water interface. Experimental data obtained with the measuring device were incorporated into a novel mathematical model, which allowed one to calculate diffusion conduction of liquid surface layer and oxygen mass transfer coefficient in the liquid surface layer. A special measurement cell was constructed. The most important part of the measurement cell is a chamber containing the electrochemical oxygen sensor inside it. Gas exchange between the volume of the chamber and the external environment takes place only through the investigated surface layer. Investigated liquid was deoxygenated, which triggers the oxygen mass transfer from the chamber through the liquid-air interface into the liquid phase. The decrease of oxygen concentration in the cell during time was measured. By using this data it is possible to calculate diffusional parameters of the water surface layer. Diffusion conduction of oxygen through the air-water surface layer of selected wastewaters was measured. The diffusion conduction of different wastewaters was about 3 to 6 times less than in the unpolluted water surface. It was observed that the dilution of wastewater does not have a significant impact on the oxygen diffusion conduction through the wastewater surface layer. This fact can be explained with the presence of the compounds with high surface activity in the wastewater. Surfactants achieved a maximum adsorption and, accordingly, the maximum decrease of oxygen permeability already at a very low concentration of surfactants in the solution. Oxygen mass transfer coefficient of the surface layer of the water is found to be Ds/ls = 0.13 x 10(-3) x cm/s. A simple technique for measuring oxygen diffusion parameters through the air-water solution surface has been developed. Derived equations enable the calculation of diffusion parameters of the surface layer at current conditions. These values of the parameters permit one to compare the resistances of the gas-liquid interface to oxygen mass transfer in the case of adsorption of different substances on the surface layer. This simple technique may be used for a determination of oxygen permeability of different water-solution surface layers. It enables one to measure the resistance to the oxygen permeability of all inflowing wastewater surface layers in the wastewater treatment plant, and to initiate a preliminary cleaning of this wastewater if required. Similarly, we can measure oxygen permeability of natural waterbodies. Especially in the case of pollution, it is important to know to what extent the oxygen permeability of the water surface layer has been decreased. Based on the tehnique presented in this research, fieldwork equipment will be developed.

Smoothed particle hydrodynamics method for evaporating multiphase flows.

PubMed

Yang, Xiufeng; Kong, Song-Charng

2017-09-01

The smoothed particle hydrodynamics (SPH) method has been increasingly used for simulating fluid flows; however, its ability to simulate evaporating flow requires significant improvements. This paper proposes an SPH method for evaporating multiphase flows. The present SPH method can simulate the heat and mass transfers across the liquid-gas interfaces. The conservation equations of mass, momentum, and energy were reformulated based on SPH, then were used to govern the fluid flow and heat transfer in both the liquid and gas phases. The continuity equation of the vapor species was employed to simulate the vapor mass fraction in the gas phase. The vapor mass fraction at the interface was predicted by the Clausius-Clapeyron correlation. An evaporation rate was derived to predict the mass transfer from the liquid phase to the gas phase at the interface. Because of the mass transfer across the liquid-gas interface, the mass of an SPH particle was allowed to change. Alternative particle splitting and merging techniques were developed to avoid large mass difference between SPH particles of the same phase. The proposed method was tested by simulating three problems, including the Stefan problem, evaporation of a static drop, and evaporation of a drop impacting a hot surface. For the Stefan problem, the SPH results of the evaporation rate at the interface agreed well with the analytical solution. For drop evaporation, the SPH result was compared with the result predicted by a level-set method from the literature. In the case of drop impact on a hot surface, the evolution of the shape of the drop, temperature, and vapor mass fraction were predicted.

Microencapsuling aerial conidia of Trichoderma harzianum through spray drying at elevated temperatures

USDA-ARS?s Scientific Manuscript database

Trichoderma conidia are mostly produced by solid fermentation systems. Inoculum is produced by liquid culturing, and then transferred to solid substrate for aerial conidial production. Aerial conidia of T. harzianum are hydrophilic in nature, and it is difficult to separate them from the solid subst...

Isolation and recovery of selected polybrominated diphenyl ethers from human serum and sheep serum: coupling reversed-phase solid-phase disk extraction and liquid-liquid extraction techniques with a capillary gas chromatographic electron capture negative ion mass spectrometric determinative technique.

PubMed

Loconto, Paul R; Isenga, David; O'Keefe, Michael; Knottnerus, Mark

2008-01-01

Polybrominated diphenyl ethers (PBDEs) are isolated and recovered with acceptable percent recoveries from human serum via liquid-liquid extraction and column chromatographic cleanup and fractionation with quantitation using capillary gas chromatography-mass spectrometry with electron capture negative ion and selected ion monitoring. PBDEs are found in unspiked serum. An alternative sample preparation approach is developed using sheep serum that utilizes a formic acid pre-treatment followed by reversed-phase solid-phase disk extraction and normal-phase solid-phase cleanup using acidified silica gel that yields>50% recoveries. When these percent recoveries are combined with a minimized phase ratio for human serum and very low instrument detection limits, method detection limits below 500 parts-per-trillion are realized.

Numerical investigation of influence on heat transfer characteristics to pneumatically conveyed dense phase flow by selecting models and boundary conditions

NASA Astrophysics Data System (ADS)

Zheng, Y.; Liu, Q.; Li, Y.

2012-03-01

Solids moving with a gas stream in a pipeline can be found in many industrial processes, such as power generation, chemical, pharmaceutical, food and commodity transfer processes. A mass flow rate of the solids is important characteristic that is often required to be measured (and controlled) to achieve efficient utilization of energy and raw materials in pneumatic conveying systems. The methods of measuring the mass flow rate of solids in a pneumatic pipeline can be divided into direct and indirect (inferential) measurements. A thermal solids' mass flow-meter, in principle, should ideally provide a direct measurement of solids flow rate, regardless of inhomogeneities in solids' distribution and environmental impacts. One key issue in developing a thermal solids' mass flow-meter is to characterize the heat transfer between the hot pipe wall and the gas-solids dense phase flow. The Eulerian continuum modeling with gas-solid two phases is the most common method for pneumatic transport. To model a gas-solid dense phase flow passing through a heated region, the gas phase is described as a continuous phase and the particles as the second phase. This study aims to describe the heat transfer characteristics between the hot wall and the gas-solids dense phase flow in pneumatic pipelines by modeling a turbulence gas-solid plug passing through the heated region which involves several actual and crucial issues: selections of interphase exchange coefficient, near-wall region functions and different wall surface temperatures. A sensitivity analysis was discussed to identify the influence on the heat transfer characteristics by selecting different interphase exchange coefficient models and different boundary conditions. Simulation results suggest that sensitivity analysis in the choice of models is very significant. The simulation results appear to show that a combination of choosing the Syamlal-O'Brien interphase exchange coefficient model and the standard k-ɛ model along with the standard wall function model might be the best approach, by which, the simulation data seems to be closest to the experimental results.

Determination of chiral pharmaceuticals and illicit drugs in wastewater and sludge using microwave assisted extraction, solid-phase extraction and chiral liquid chromatography coupled with tandem mass spectrometry.

PubMed

Evans, Sian E; Davies, Paul; Lubben, Anneke; Kasprzyk-Hordern, Barbara

2015-07-02

This is the first study presenting a multi-residue method allowing for comprehensive analysis of several chiral pharmacologically active compounds (cPACs) including beta-blockers, antidepressants and amphetamines in wastewater and digested sludge at the enantiomeric level. Analysis of both the liquid and solid matrices within wastewater treatment is crucial to being able to carry out mass balance within these systems. The method developed comprises filtration, microwave assisted extraction and solid phase extraction followed by chiral liquid chromatography coupled with tandem mass spectrometry to analyse the enantiomers of 18 compounds within all three matrices. The method was successfully validated for 10 compounds within all three matrices (amphetamine, methamphetamine, MDMA, MDA, venlafaxine, desmethylvenlafaxine, citalopram, metoprolol, propranolol and sotalol), 7 compounds validated for the liquid matrices only (mirtazapine, salbutamol, fluoxetine, desmethylcitalopram, atenolol, ephedrine and pseudoephedrine) and 1 compound (alprenolol) passing the criteria for solid samples only. The method was then applied to wastewater samples; cPACs were found at concentration ranges in liquid matrices of: 1.7 ng L(-1) (metoprolol) - 1321 ng L(-1) (tramadol) in influent,

[INVITED] Laser-induced forward transfer: A high resolution additive manufacturing technology

NASA Astrophysics Data System (ADS)

Delaporte, Philippe; Alloncle, Anne-Patricia

2016-04-01

Among the additive manufacturing techniques, laser-induced forward transfer addresses the challenges of printing thin films in solid phase or small volume droplets in liquid phase with very high resolution. This paper reviews the physics of this process and explores the pros and cons of this technology versus other digital printing technologies. The main field of applications are printed electronics, organic electronics and tissue engineering, and the most promising short terms ones concern digital laser printing of sensors and conductive tracks. Future directions and emerging areas of interest are discussed such as printing solid from a liquid phase and 3D digital nanomanufacturing.

Material Selection for Microchannel Heatsink: Conjugate Heat Transfer Simulation

NASA Astrophysics Data System (ADS)

Uday Kumar, A.; Javed, Arshad; Dubey, Satish K.

2018-04-01

Heat dissipation during the operation of electronic devices causes rise in temperature, which demands an effective thermal management for their performance, life and reliability. Single phase liquid cooling in microchannels is an effective and proven technology for electronics cooling. However, due to the ongoing trends of miniaturization and developments in the microelectronics technology, the future needs of heat flux dissipation rate are expected to rise to 1 kW/cm2. Air cooled systems are unable to meet this demand. Hence, liquid cooled heatsinks are preferred. This paper presents conjugate heat transfer simulation of single phase flow in microchannels with application to electronic cooling. The numerical model is simulated for different materials: copper, aluminium and silicon as solid and water as liquid coolant. The performances of microchannel heatsink are analysed for mass flow rate range of 20-40 ml/min. The investigation has been carried out on same size of electronic chip and heat flux in order to have comparative study of different materials. This paper is divided into two sections: fabrication techniques and numerical simulation for different materials. In the first part, a brief discussion of fabrication techniques of microchannel heatsink have been presented. The second section presents conjugate heat transfer simulation and parametric investigation for different material microchannel heatsink. The presented study and findings are useful for selection of materials for microchannel heatsink.

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.

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.

Diffusion relaxation times of nonequilibrium isolated small bodies and their solid phase ensembles to equilibrium states

NASA Astrophysics Data System (ADS)

Tovbin, Yu. K.

2017-08-01

The possibility of obtaining analytical estimates in a diffusion approximation of the times needed by nonequilibrium small bodies to relax to their equilibrium states based on knowledge of the mass transfer coefficient is considered. This coefficient is expressed as the product of the self-diffusion coefficient and the thermodynamic factor. A set of equations for the diffusion transport of mixture components is formulated, characteristic scales of the size of microheterogeneous phases are identified, and effective mass transfer coefficients are constructed for them. Allowing for the developed interface of coexisting and immiscible phases along with the porosity of solid phases is discussed. This approach can be applied to the diffusion equalization of concentrations of solid mixture components in many physicochemical systems: the mutual diffusion of components in multicomponent systems (alloys, semiconductors, solid mixtures of inert gases) and the mass transfer of an absorbed mobile component in the voids of a matrix consisting of slow components or a mixed composition of mobile and slow components (e.g., hydrogen in metals, oxygen in oxides, and the transfer of molecules through membranes of different natures, including polymeric).

Self-pressurization of a spherical liquid hydrogen storage tank in a microgravity environment

NASA Technical Reports Server (NTRS)

Lin, C. S.; Hasan, M. M.

1992-01-01

Thermal stratification and self-pressurization of partially filled liquid hydrogen (LH2) storage tanks under microgravity condition is studied theoretically. A spherical tank is subjected to a uniform and constant wall heat flux. It is assumed that a vapor bubble is located in the tank center such that the liquid-vapor interface and tank wall form two concentric spheres. This vapor bubble represents an idealized configuration of a wetting fluid in microgravity conditions. Dimensionless mass and energy conservation equations for both vapor and liquid regions are numerically solved. Coordinate transformation is used to capture the interface location which changes due to liquid thermal expansion, vapor compression, and mass transfer at liquid-vapor interface. The effects of tank size, liquid fill level, and wall heat flux on the pressure rise and thermal stratification are studied. Liquid thermal expansion tends to cause vapor condensation and wall heat flux tends to cause liquid evaporation at the interface. The combined effects determine the direction of mass transfer at the interface. Liquid superheat increases with increasing wall heat flux and liquid fill level and approaches an asymptotic value.

Saponification reaction system: a detailed mass transfer coefficient determination.

PubMed

Pečar, Darja; Goršek, Andreja

2015-01-01

The saponification of an aromatic ester with an aqueous sodium hydroxide was studied within a heterogeneous reaction medium in order to determine the overall kinetics of the selected system. The extended thermo-kinetic model was developed compared to the previously used simple one. The reaction rate within a heterogeneous liquid-liquid system incorporates a chemical kinetics term as well as mass transfer between both phases. Chemical rate constant was obtained from experiments within a homogeneous medium, whilst the mass-transfer coefficient was determined separately. The measured thermal profiles were then the bases for determining the overall reaction-rate. This study presents the development of an extended kinetic model for considering mass transfer regarding the saponification of ethyl benzoate with sodium hydroxide within a heterogeneous reaction medium. The time-dependences are presented for the mass transfer coefficient and the interfacial areas at different heterogeneous stages and temperatures. The results indicated an important role of reliable kinetic model, as significant difference in k(L)a product was obtained with extended and simple approach.

Beyond the standard two-film theory: Computational fluid dynamics simulations for carbon dioxide capture in a wetted wall column

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Chao; Xu, Zhijie; Lai, Canhai

The standard two-film theory (STFT) is a diffusion-based mechanism that can be used to describe gas mass transfer across liquid film. Fundamental assumptions of the STFT impose serious limitations on its ability to predict mass transfer coefficients. To better understand gas absorption across liquid film in practical situations, a multiphase computational fluid dynamics (CFD) model fully equipped with mass transport and chemistry capabilities has been developed for solvent-based carbon dioxide (CO 2) capture to predict the CO 2 mass transfer coefficient in a wetted wall column. The hydrodynamics is modeled using a volume of fluid method, and the diffusive andmore » reactive mass transfer between the two phases is modeled by adopting a one-fluid formulation. We demonstrate that the proposed CFD model can naturally account for the influence of many important factors on the overall mass transfer that cannot be quantitatively explained by the STFT, such as the local variation in fluid velocities and properties, flow instabilities, and complex geometries. The CFD model also can predict the local mass transfer coefficient variation along the column height, which the STFT typically does not consider.« less

Beyond the standard two-film theory: Computational fluid dynamics simulations for carbon dioxide capture in a wetted wall column

DOE PAGES

Wang, Chao; Xu, Zhijie; Lai, Canhai; ...

2018-03-27

The standard two-film theory (STFT) is a diffusion-based mechanism that can be used to describe gas mass transfer across liquid film. Fundamental assumptions of the STFT impose serious limitations on its ability to predict mass transfer coefficients. To better understand gas absorption across liquid film in practical situations, a multiphase computational fluid dynamics (CFD) model fully equipped with mass transport and chemistry capabilities has been developed for solvent-based carbon dioxide (CO 2) capture to predict the CO 2 mass transfer coefficient in a wetted wall column. The hydrodynamics is modeled using a volume of fluid method, and the diffusive andmore » reactive mass transfer between the two phases is modeled by adopting a one-fluid formulation. We demonstrate that the proposed CFD model can naturally account for the influence of many important factors on the overall mass transfer that cannot be quantitatively explained by the STFT, such as the local variation in fluid velocities and properties, flow instabilities, and complex geometries. The CFD model also can predict the local mass transfer coefficient variation along the column height, which the STFT typically does not consider.« less

Characterization of rhamnolipids by liquid chromatography/mass spectrometry after solid-phase extraction.

PubMed

Behrens, Beate; Engelen, Jeannine; Tiso, Till; Blank, Lars Mathias; Hayen, Heiko

2016-04-01

Rhamnolipids are surface-active agents with a broad application potential that are produced in complex mixtures by bacteria of the genus Pseudomonas. Analysis from fermentation broth is often characterized by laborious sample preparation and requires hyphenated analytical techniques like liquid chromatography coupled to mass spectrometry (LC-MS) to obtain detailed information about sample composition. In this study, an analytical procedure based on chromatographic method development and characterization of rhamnolipid sample material by LC-MS as well as a comparison of two sample preparation methods, i.e., liquid-liquid extraction and solid-phase extraction, is presented. Efficient separation was achieved under reversed-phase conditions using a mixed propylphenyl and octadecylsilyl-modified silica gel stationary phase. LC-MS/MS analysis of a supernatant from Pseudomonas putida strain KT2440 pVLT33_rhlABC grown on glucose as sole carbon source and purified by solid-phase extraction revealed a total of 20 congeners of di-rhamnolipids, mono-rhamnolipids, and their biosynthetic precursors 3-(3-hydroxyalkanoyloxy)alkanoic acids (HAAs) with different carbon chain lengths from C8 to C14, including three rhamnolipids with uncommon C9 and C11 fatty acid residues. LC-MS and the orcinol assay were used to evaluate the developed solid-phase extraction method in comparison with the established liquid-liquid extraction. Solid-phase extraction exhibited higher yields and reproducibility as well as lower experimental effort.

An inverse gas chromatographic methodology for studying gas-liquid mass transfer.

PubMed

Paloglou, A; Martakidis, K; Gavril, D

2017-01-13

A novel methodology of reversed flow inverse gas chromatography (RF-IGC) is presented. It permits the simultaneous determination of mass transfer coefficients across the gas liquid interface as well as the respective solubility parameters and thermodynamic functions of dissolution of gases into liquids. The standard deviation of the experimentally determined parameters is estimated for first time, which combined with the successful comparison of the values of the present parameters with other literature ones ascertain the reliability of the methodology. Another novelty of the present work is that the chromatographic sampling of the physicochemical phenomena is done without performing the usual flow reversals procedure. Vinyl chloride monomer's (VCM) interaction with various composition liquid foods: orange juice, milk and olive oil was used as model system. The present transfer rates are controlled by the gas film at lower temperatures, but at higher temperatures the resistances in both films tend to become equal. The found liquid diffusivity values express the total mass transfer from the gas phase into the liquid's bulk and they decrease with rising temperature, as the solubilities of gases in liquids do. Solubility, expressed by Henry's law constant and the mean values of interfacial thickness are of the same order of magnitude to literature ones. From the thermodynamic point of view, VCM dissolution in all liquids is accompanied by significant heat release and it is a slightly non-spontaneous process, near equilibrium, while the entropy change values are negative. Copyright © 2016 Elsevier B.V. All rights reserved.

Consumption of added sugars from liquid but not solid sources predicts impaired glucose homeostasis and insulin resistance among youth at risk of obesity.

PubMed

Wang, Jiawei; Light, Kelly; Henderson, Mélanie; O'Loughlin, Jennifer; Mathieu, Marie-Eve; Paradis, Gilles; Gray-Donald, Katherine

2014-01-01

Little is known about longitudinal associations between added sugar consumption (solid and liquid sources) and glucose-insulin homeostasis among youth. Caucasian children (8-10 y) with at least one obese biological parent were recruited in the QUébec Adipose and Lifestyle InvesTigation in Youth (QUALITY) cohort (n = 630) and followed-up 2 y later (n = 564). Added sugars were assessed by 3 24-h dietary recalls at baseline. Two-year changes were examined in multivariate linear regression models, adjusting for baseline level, age, sex, Tanner stage, energy intake, fat mass (dual-energy X-ray absorptiometry), and physical activity (7 d accelerometer). Added sugar intake in either liquid or solid sources was not related to changes in adiposity measures (fat mass, body mass index, or waist circumference). However, a higher consumption (10 g/d) of added sugars from liquid sources was associated with 0.04 mmol/L higher fasting glucose, 2.3 pmol/L higher fasting insulin, 0.1 unit higher homeostasis model assessment of insulin resistance (HOMA-IR), and 0.4 unit lower Matsuda-insulin sensitivity index (Matsuda-ISI) in all participants (P < 0.01). No associations were observed with consumption of added sugars from solid sources. Overweight/obese children at baseline had greater increases in adiposity indicators, fasting insulin, and HOMA-IR and decreases in Matsuda-ISI during those 2 y than normal-weight children. Consumption of added sugars from liquid or solid sources was not associated with changes in adiposity, but liquid added sugars were a risk factor for the development of impaired glucose homeostasis and insulin resistance over 2 y among youth at risk of obesity.

Performance evaluation of a liquid tin anode solid oxide fuel cell operating under hydrogen, argon and coal

NASA Astrophysics Data System (ADS)

Khurana, Sanchit; LaBarbera, Mark; Fedkin, Mark V.; Lvov, Serguei N.; Abernathy, Harry; Gerdes, Kirk

2015-01-01

A liquid tin anode solid oxide fuel cell is constructed and investigated under different operating conditions. Electrochemical Impedance Spectroscopy (EIS) is used to reflect the effect of fuel feed as the EIS spectra changes significantly on switching the fuel from argon to hydrogen. A cathode symmetric cell is used to separate the impedance from the two electrodes, and the results indicate that a major contribution to the charge-transfer and mass-transfer impedance arises from the anode. The OCP of 0.841 V for the cell operating under argon as a metal-air battery indicates the formation of a SnO2 layer at the electrolyte/anode interface. The increase in the OCP to 1.1 V for the hydrogen fueled cell shows that H2 reduces the SnO2 film effectively. The effective diffusion coefficients are calculated using the Warburg element in the equivalent circuit model for the experimental EIS data, and the values of 1.9 10-3 cm2 s-1 at 700 °C, 2.3 10-3 cm2 s-1 at 800 °C and 3.5 10-3 cm2 s-1 at 900 °C indicate the system was influenced by diffusion of hydrogen in the system. Further, the performance degradation over time is attributed to the irreversible conversion of Sn to SnO2 resulting from galvanic polarization.

Numerical simulation of water evaporation inside vertical circular tubes

NASA Astrophysics Data System (ADS)

Ocłoń, Paweł; Nowak, Marzena; Majewski, Karol

2013-10-01

In this paper the results of simplified numerical analysis of water evaporation in vertical circular tubes are presented. The heat transfer in fluid domain (water or wet steam) and solid domain (tube wall) is analyzed. For the fluid domain the temperature field is calculated solving energy equation using the Control Volume Method and for the solid domain using the Finite Element Method. The heat transfer between fluid and solid domains is conjugated using the value of heat transfer coefficient from evaporating liquid to the tube wall. It is determined using the analytical Steiner-Taborek correlation. The pressure changes in fluid are computed using Friedel model.

ON SITE SOLID-PHASE EXTRACTION AND LABORATORY ANALYSIS OF ULTRA-TRACE SYNTHETIC MUSKS IN MUNICIPAL SEWAGE EFFLUENT USING GAS CHROMATOGRAPHY-MASS SPECTROMETRY. FULL-SCAN MODE

EPA Science Inventory

Fragrance materials such as synthetic musks in aqueous samples, are normally determined by gas chromatography/mass spectrometry in the selected ion monitoring (SIM) mode to provide maximum sensitivity after liquid-liquid extraction of I -L samples. Full-scan mass spectra are requ...

The Heat and Mass Transfer Processes at the Cooling of Strong Heated Sphere in a Cold Liquid

NASA Astrophysics Data System (ADS)

Puzina, Yu Yu

2017-10-01

Some new experimental results of continuum mechanics problems in two-phase systems are described. The processes of heat and mass transfer during cooling of strong heated sphere in the subcooled liquid are studied. Due to high level of heater temperature the stable vapor film is formed on the sphere surface. Calculation of steady-state transport processes at vapor - water interface is carried out using methods of molecular-kinetic theory. Heat transfer in vapor by thermal conductivity and natural convection in liquid are considered. Pressure balance is provided by hydrostatic pressure and non-equilibrium boundary condition. The results of the calculations are analyzed by comparison with previous data and experimental results.

Numerical Simulation of Polysilicon Solid-liquid Interface Transmogrification in Heat Transfer Process

NASA Astrophysics Data System (ADS)

Yang, Xi; Ma, Wenhui; Lv, Guoqiang; Zhang, Mingyu

2018-01-01

The shape of solid-liquid interface during the directional solidification process, which is difficult to be observed and measured in actual processes, controls the grain orientation and grain size of polysilicon ingot. We carried out numerical calculations of the directional solidification progress of polycrystalline silicon and invested the means to deal with the latent heat of solidification in numerical simulation. The distributions of the temperature field of the melt for the crystallization progress as well as the transformation of the solid-liquid interface were obtained. The simulation results are consistent with the experimental outcomes. The results show that the curvature of solid-liquid interface is small and stability, larger grain sized columnar crystal can be grown in the laboratory-scale furnace at a solidification rate of 10 μm•s-1. It shall provide important theoretical basis for metallurgical process and polysilicon production technology.

Oxidation reactions of solid carbonaceous and resinous substances in supercritical water

DOE Office of Scientific and Technical Information (OSTI.GOV)

Koda, S.

Recent kinetic studies, particularly those by means of shadowgraphy and X-ray radiography, for supercritical water oxidation of solid carbonaceous and resinous substances have revealed the importance of the O{sub 2} mass transfer process over the intrinsic surface reaction at higher temperatures. The mass transfer processes, internal and external one, should be incorporated in designing SCWO processes for solid substances and related processes such as catalytic SCWO. Some model calculation efforts of late are briefly described. Finally, fundamental information required for future development is itemed.

Modelling mass transfer during venting/soil vapour extraction: Non-aqueous phase liquid/gas mass transfer coefficient estimation

NASA Astrophysics Data System (ADS)

Esrael, D.; Kacem, M.; Benadda, B.

2017-07-01

We investigate how the simulation of the venting/soil vapour extraction (SVE) process is affected by the mass transfer coefficient, using a model comprising five partial differential equations describing gas flow and mass conservation of phases and including an expression accounting for soil saturation conditions. In doing so, we test five previously reported quations for estimating the non-aqueous phase liquid (NAPL)/gas initial mass transfer coefficient and evaluate an expression that uses a reference NAPL saturation. Four venting/SVE experiments utilizing a sand column are performed with dry and non-saturated sand at low and high flow rates, and the obtained experimental results are subsequently simulated, revealing that hydrodynamic dispersion cannot be neglected in the estimation of the mass transfer coefficient, particularly in the case of low velocities. Among the tested models, only the analytical solution of a convection-dispersion equation and the equation proposed herein are suitable for correctly modelling the experimental results, with the developed model representing the best choice for correctly simulating the experimental results and the tailing part of the extracted gas concentration curve.

Two-Dimensional Nanoporous Networks Formed by Liquid-to-Solid Transfer of Hydrogen-Bonded Macrocycles Built from DNA Bases.

PubMed

Bilbao, Nerea; Destoop, Iris; De Feyter, Steven; González-Rodríguez, David

2016-01-11

We present an approach that makes use of DNA base pairing to produce hydrogen-bonded macrocycles whose supramolecular structure can be transferred from solution to a solid substrate. A hierarchical assembly process ultimately leads to two-dimensional nanostructured porous networks that are able to host size-complementary guests. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

An effect of surface properties on detachment of adhered solid to cooling surface for formation of clathrate hydrate slurry

NASA Astrophysics Data System (ADS)

Daitoku, Tadafumi; Utaka, Yoshio

In air-conditioning systems, it is desirable that the liquid-solid phase change temperature of a cool energy storage material is approximately 10 °C from the perspective of improving coefficient of performance (COP). Moreover, a thermal storage material that forms slurry can realize large heat capacity of working fluids. Since the solid that adheres to the heat transfer surface forms a thermal resistance layer and remarkably reduces the rate of cold storage, it is important to avoid the adhesion of a thick solid layer on the surface so as to realize efficient energy storage. Considering a harvest type cooling unit, the force required for removing the solid phase from the heat transfer surface was studied. Tetra-n-butylammonium Bromide (TBAB) clathrate hydrate was used as a cold storage material. The effect of the heat transfer surface properties on the scraping force for detachment of adhered solid of TBAB hydrate to the heat transfer surface was examined experimentally.

New design for a time-of-flight mass spectrometer with a liquid beam laser desorption ion source for the analysis of biomolecules

NASA Astrophysics Data System (ADS)

Charvat, A.; Lugovoj, E.; Faubel, M.; Abel, B.

2004-05-01

We describe a novel liquid beam mass spectrometer, based on a recently discovered nanosecond laser desorption phenomenon, [W. Kleinekofort, J. Avdiev, and B. Brutschy, Int. J. Mass Ion. Processes 152, 135 (1996)] which allows the liquid-to-vacuum transfer, and subsequent mass analysis of pre-existing ions and ionic associates from liquid microjets of aqueous solutions. The goal of our novel technical approach is to establish a system with good mass resolution that implements improvements on critical components that make the system more reliable and easier to operate. For laser desorption pulsed dye-laser difference frequency mixing is used that provides tunable infrared light near the absorption maximum of liquid water around 3 μm. Different types of liquid beam glass nozzles (convergent capillary and aperture plate nozzles) are investigated and characterized. Starting from theoretical considerations of hydrodynamic drag forces on micrometer size droplets in supersonic rarefied gas flows we succeeded in capturing efficiently the liquid beam in a liquid beam recycling trap operating at the vapor pressure of liquid water. For improving the pollution resistance, the liquid jet high vacuum ion source region is spatially separated from the reflectron time-of-flight mass spectrometer (TOF-MS) working behind a gate valve in an ultrahigh vacuum environment. A simple (simulation optimized) ion optics is employed for the ion transfer from the source to the high vacuum region. This new feature is also mostly responsible for the improved mass resolution. With the present tandem-TOF-MS setup a resolution of m/Δm≈1800 for the low and m/Δm≈700 in the high mass region has been obtained for several biomolecules of different mass and complexity (amino acids, insulin, and cytochrome c).

Design of fluidized-bed fermentors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Andrews, G.F.; Przezdziecki, J.

1986-06-01

Designing a fluidized-bed bioreactor requires choosing the best support particle (if any). Effectiveness factors (proportional to reactor volumetric productivity) are derived for flocs, solid spherical supports, porous supports, and adsorbent supports. The derivation demonstrates a mathematical procedure for reducing the diffusion/uptake equations for many components (substrates and inhibitory products) to a single equation, and for identifying the limiting component. With solid supports there exists a film thickness that maximizes the effectiveness, and the design objective is to keep the film near this optimum throughout the bed. This involves consideration of the effect of support particle density and film growth onmore » bed stratification. Other considerations in packing support particles are obtaining reasonable values for bed height and diameter, minimizing mass transfer resistance between liquid and biomass, and preventing surface shear from stripping off the biomass. 20 references.« less

Liquid-like thermal conduction in intercalated layered crystalline solids

DOE PAGES

Li, B.; Wang, H.; Kawakita, Y.; ...

2018-01-15

As a generic property, all substances transfer heat through microscopic collisions of constituent particles. A solid conducts heat through both transverse and longitudinal acoustic phonons, but a liquid employs only longitudinal vibrations. As a result, a solid is usually thermally more conductive than a liquid. In canonical viewpoints, such a difference also serves as the dynamic signature distinguishing a solid from a liquid. Here in this work, we report liquid-like thermal conduction observed in the crystalline AgCrSe 2. The transverse acoustic phonons are completely suppressed by the ultrafast dynamic disorder while the longitudinal acoustic phonons are strongly scattered but survive,more » and are thus responsible for the intrinsically ultralow thermal conductivity. This scenario is applicable to a wide variety of layered compounds with heavy intercalants in the van der Waals gaps, manifesting a broad implication on suppressing thermal conduction. Finally, these microscopic insights might reshape the fundamental understanding on thermal transport properties of matter and open up a general opportunity to optimize performances of thermoelectrics.« less

Liquid-like thermal conduction in intercalated layered crystalline solids

NASA Astrophysics Data System (ADS)

Li, B.; Wang, H.; Kawakita, Y.; Zhang, Q.; Feygenson, M.; Yu, H. L.; Wu, D.; Ohara, K.; Kikuchi, T.; Shibata, K.; Yamada, T.; Ning, X. K.; Chen, Y.; He, J. Q.; Vaknin, D.; Wu, R. Q.; Nakajima, K.; Kanatzidis, M. G.

2018-03-01

As a generic property, all substances transfer heat through microscopic collisions of constituent particles1. A solid conducts heat through both transverse and longitudinal acoustic phonons, but a liquid employs only longitudinal vibrations2,3. As a result, a solid is usually thermally more conductive than a liquid. In canonical viewpoints, such a difference also serves as the dynamic signature distinguishing a solid from a liquid. Here, we report liquid-like thermal conduction observed in the crystalline AgCrSe2. The transverse acoustic phonons are completely suppressed by the ultrafast dynamic disorder while the longitudinal acoustic phonons are strongly scattered but survive, and are thus responsible for the intrinsically ultralow thermal conductivity. This scenario is applicable to a wide variety of layered compounds with heavy intercalants in the van der Waals gaps, manifesting a broad implication on suppressing thermal conduction. These microscopic insights might reshape the fundamental understanding on thermal transport properties of matter and open up a general opportunity to optimize performances of thermoelectrics.

Liquid-like thermal conduction in intercalated layered crystalline solids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, B.; Wang, H.; Kawakita, Y.

As a generic property, all substances transfer heat through microscopic collisions of constituent particles. A solid conducts heat through both transverse and longitudinal acoustic phonons, but a liquid employs only longitudinal vibrations. As a result, a solid is usually thermally more conductive than a liquid. In canonical viewpoints, such a difference also serves as the dynamic signature distinguishing a solid from a liquid. Here in this work, we report liquid-like thermal conduction observed in the crystalline AgCrSe 2. The transverse acoustic phonons are completely suppressed by the ultrafast dynamic disorder while the longitudinal acoustic phonons are strongly scattered but survive,more » and are thus responsible for the intrinsically ultralow thermal conductivity. This scenario is applicable to a wide variety of layered compounds with heavy intercalants in the van der Waals gaps, manifesting a broad implication on suppressing thermal conduction. Finally, these microscopic insights might reshape the fundamental understanding on thermal transport properties of matter and open up a general opportunity to optimize performances of thermoelectrics.« less

Ambient-Pressure X-ray Photoelectron Spectroscopy to Characterize the Solid/Liquid Interface: Probing the Electrochemical Double Layer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Favaro, Marco; Liu, Zhi; Crumlin, Ethan J.

Ambient-pressure X-ray photoelectron spectroscopy (APXPS) has contributed greatly to a wide range of research fields, including environmental science, catalysis, and electrochemistry, to name a few. The use of this technique at synchrotron facilities primarily focused on probing the solid/gas interface; however, it quickly advanced to the probing of liquid/vapor interfaces and solid/liquid interfaces through an X-ray-transparent window. Most recently, combining APXPS with “Tender” X-rays (~2.5 keV to 8 keV) on beamline 9.3.1 at the Advanced Light Source in Lawrence Berkeley National Laboratory (which can generate photoelectrons with much longer inelastic mean free paths) has enabled us to probe the solid/liquidmore » interface without needing a window. This innovation allows us to probe interfacial chemistries of electrochemically controlled solid/liquid interfaces undergoing charge transfer reactions. Lastly, these advancements have transitioned APXPS from a traditional surface science tool to an essential interface science technique.« less

Development of a household waste treatment subsystem, volume 1. [with water conservation features

NASA Technical Reports Server (NTRS)

Gresko, T. M.; Murray, R. W.

1973-01-01

The domestic waste treatment subsystem was developed to process the daily liquid and non-metallic solid wastes provided by a family of four people. The subsystem was designed to be connected to the sewer line of a household which contained water conservation features. The system consisted of an evaporation technique to separate liquids from solids, an incineration technique for solids reduction, and a catalytic oxidizer for eliminating noxious gases from evaporation and incineration processes. All wastes were passed through a grinder which masticated the solids and deposited them in a settling tank. The liquids were transferred through a cleanable filter into a holding tank. From here the liquids were sprayed into an evaporator and a spray chamber where evaporation occurred. The resulting vapors were processed by catalytic oxidation. Water and latent energy were recovered in a combination evaporator/condenser heat exchanger. The solids were conveyed into an incinerator and reduced to ash while the incineration gases were passed through the catalytic oxidizer along with the processed water vapor.

Ambient-Pressure X-ray Photoelectron Spectroscopy to Characterize the Solid/Liquid Interface: Probing the Electrochemical Double Layer

DOE PAGES

Favaro, Marco; Liu, Zhi; Crumlin, Ethan J.

2017-03-31

Ambient-pressure X-ray photoelectron spectroscopy (APXPS) has contributed greatly to a wide range of research fields, including environmental science, catalysis, and electrochemistry, to name a few. The use of this technique at synchrotron facilities primarily focused on probing the solid/gas interface; however, it quickly advanced to the probing of liquid/vapor interfaces and solid/liquid interfaces through an X-ray-transparent window. Most recently, combining APXPS with “Tender” X-rays (~2.5 keV to 8 keV) on beamline 9.3.1 at the Advanced Light Source in Lawrence Berkeley National Laboratory (which can generate photoelectrons with much longer inelastic mean free paths) has enabled us to probe the solid/liquidmore » interface without needing a window. This innovation allows us to probe interfacial chemistries of electrochemically controlled solid/liquid interfaces undergoing charge transfer reactions. Lastly, these advancements have transitioned APXPS from a traditional surface science tool to an essential interface science technique.« less

Serrating Nozzle Surfaces for Complete Transfer of Droplets

NASA Technical Reports Server (NTRS)

Kim, Chang-Jin " CJ" ; Yi, Uichong

2010-01-01

A method of ensuring the complete transfer of liquid droplets from nozzles in microfluidic devices to nearby surfaces involves relatively simple geometric modification of the nozzle surfaces. The method is especially applicable to nozzles in print heads and similar devices required to dispense liquid droplets having precise volumes. Examples of such devices include heads for soft printing of ink on paper and heads for depositing droplets of deoxyribonucleic acid (DNA) or protein solutions on glass plates to form microarrays of spots for analysis. The main purpose served by the present method is to ensure that droplets transferred from a nozzle have consistent volume, as needed to ensure accuracy in microarray analysis or consistent appearance of printed text and images. In soft printing, droplets having consistent volume are generated inside a print head, but in the absence of the present method, the consistency is lost in printing because after each printing action (in which a drop is ejected from a nozzle), a small residual volume of liquid remains attached to the nozzle. By providing for complete transfer of droplets (and thus eliminating residual liquid attached to the nozzle) the method ensures consistency of volume of transferred droplets. An additional benefit of elimination of residue is prevention of cross-contamination among different liquids printed through the same nozzle a major consideration in DNA microarray analysis. The method also accelerates the printing process by minimizing the need to clean a printing head to prevent cross-contamination. Soft printing involves a hydrophobic nozzle surface and a hydrophilic print surface. When the two surfaces are brought into proximity such that a droplet in the nozzle makes contact with the print surface, a substantial portion of the droplet becomes transferred to the print surface. Then as the nozzle and the print surface are pulled apart, the droplet is pulled apart and most of the droplet remains on the print surface. The basic principle of the present method is to reduce the liquid-solid surface energy of the nozzle to a level sufficiently below the intrinsic solid-liquid surface energy of the nozzle material so that the droplet is not pulled apart and, instead, the entire droplet volume becomes transferred to the print surface. In this method, the liquid-solid surface energy is reduced by introducing artificial surface roughness in the form of micromachined serrations on the inner nozzle surface (see figure). The method was tested in experiments on soft printing of DNA solutions and of deionized water through 0.5-mm-diameter nozzles, of which some were not serrated, some were partially serrated, and some were fully serrated. In the nozzles without serrations, transfer was incomplete; that is, residual liquids remained in the nozzles after printing. However, in every nozzle in which at least half the inner surface was serrated, complete transfer of droplets to the print surface was achieved.

Beyond the standard two-film theory: Computational fluid dynamics simulations for carbon dioxide capture in a wetted wall column

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Chao; Xu, Zhijie; Lai, Canhai

The standard two-film theory (STFT) is a diffusion-based mechanism that can be used to describe gas mass transfer across liquid film. Fundamental assumptions of the STFT impose serious limitations on its ability to predict mass transfer coefficients. To better understand gas absorption across liquid film in practical situations, a multiphase computational fluid dynamics (CFD) model fully equipped with mass transport and chemistry capabilities has been developed for solvent-based carbon dioxide (CO2) capture to predict the CO2 mass transfer coefficient in a wetted wall column. The hydrodynamics is modeled using a volume of fluid method, and the diffusive and reactive massmore » transfer between the two phases is modeled by adopting a one-fluid formulation. We demonstrate that the proposed CFD model can naturally account for the influence of many important factors on the overall mass transfer that cannot be quantitatively explained by the STFT, such as the local variation in fluid velocities and properties, flow instabilities, and complex geometries. The CFD model also can predict the local mass transfer coefficient variation along the column height, which the STFT typically does not consider.« less

The effect of the London-van der Waals dispersion force on interline heat transfer

NASA Technical Reports Server (NTRS)

Wayner, P. C., Jr.

1978-01-01

A theoretical procedure to determine the heat transfer characteristics of the interline region (junction of liquid-solid-vapor) from the macroscopic optical and thermophysical properties of the system is outlined. The analysis is based on the premise that the interline transport processes are controlled by the London-van der Waals dispersion force between condensed phases (solid and liquid). Numerical values of the dispersion constant are presented. The procedure is used to compare the relative size of the interline heat sink of various systems using a constant heat flux mode. This solution demonstrates the importance of the interline heat flow number, which is evaluated for various systems.

Study of Rapid-Regression Liquefying Hybrid Rocket Fuels

NASA Technical Reports Server (NTRS)

Zilliac, Greg; DeZilwa, Shane; Karabeyoglu, M. Arif; Cantwell, Brian J.; Castellucci, Paul

2004-01-01

A report describes experiments directed toward the development of paraffin-based hybrid rocket fuels that burn at regression rates greater than those of conventional hybrid rocket fuels like hydroxyl-terminated butadiene. The basic approach followed in this development is to use materials such that a hydrodynamically unstable liquid layer forms on the melting surface of a burning fuel body. Entrainment of droplets from the liquid/gas interface can substantially increase the rate of fuel mass transfer, leading to surface regression faster than can be achieved using conventional fuels. The higher regression rate eliminates the need for the complex multi-port grain structures of conventional solid rocket fuels, making it possible to obtain acceptable performance from single-port structures. The high-regression-rate fuels contain no toxic or otherwise hazardous components and can be shipped commercially as non-hazardous commodities. Among the experiments performed on these fuels were scale-up tests using gaseous oxygen. The data from these tests were found to agree with data from small-scale, low-pressure and low-mass-flux laboratory tests and to confirm the expectation that these fuels would burn at high regression rates, chamber pressures, and mass fluxes representative of full-scale rocket motors.

Single Laboratory Validated Method for Determination of Microcystins and Nodularin in Ambient Freshwaters by Solid Phase Extraction and Liquid Chromatography/ Tandem Mass Spectrometry (LC/MS/MS)

EPA Pesticide Factsheets

This document is a standardized, single laboratory validated liquid chromatography/tandem mass spectrometry (LC/MS/MS) method for the detection of cyanotoxins—microsystins and nodularin (combined intracellular and extracellular)—in ambient freshwaters.

Simultaneous determination of estrogens and progestogens in honey using high performance liquid chromatography-tandem mass spectrometry

USDA-ARS?s Scientific Manuscript database

This work describes the development and validation of a method for the simultaneous determination of 13 estrogens and progestogens in honey by high performance liquid chromatography-tandem mass spectrometry. The target compounds were preconcentrated by solid phase extraction. Pretreatment variables ...

ON-SITE SOLID-PHASE EXTRACTION AND LABORATORY ANALYSIS OF ULTRA-TRACE SYNTHETIC MUSKS IN MUNICIPAL SEWAGE EFFLUENT USING GAS CHROMATOGRAPHY-MASS SPECTROMETRY IN THE FULL-SCAN MODE

EPA Science Inventory

Fragrance materials such as synthetic musks in aqueous samples, are normally determined by gas chromatography/mass spectrometry in the selected ion monitoring (SIM) mode to provide maximum sensitivity after liquid-liquid extraction of I -L samples. Full-scan mass spectra are requ...

Determination of volumetric gas-liquid mass transfer coefficient of carbon monoxide in a batch cultivation system using kinetic simulations.

PubMed

Jang, Nulee; Yasin, Muhammad; Park, Shinyoung; Lovitt, Robert W; Chang, In Seop

2017-09-01

A mathematical model of microbial kinetics was introduced to predict the overall volumetric gas-liquid mass transfer coefficient (k L a) of carbon monoxide (CO) in a batch cultivation system. The cell concentration (X), acetate concentration (C ace ), headspace gas (N co and [Formula: see text] ), dissolved CO concentration in the fermentation medium (C co ), and mass transfer rate (R) were simulated using a variety of k L a values. The simulated results showed excellent agreement with the experimental data for a k L a of 13/hr. The C co values decreased with increase in cultivation times, whereas the maximum mass transfer rate was achieved at the mid-log phase due to vigorous microbial CO consumption rate higher than R. The model suggested in this study may be applied to a variety of microbial systems involving gaseous substrates. Copyright © 2017 Elsevier Ltd. All rights reserved.

One-dimensional thermohydraulic code THESEUS and its application to chilldown process simulation in two-phase hydrogen flows

NASA Astrophysics Data System (ADS)

Papadimitriou, P.; Skorek, T.

THESUS is a thermohydraulic code for the calculation of steady state and transient processes of two-phase cryogenic flows. The physical model is based on four conservation equations with separate liquid and gas phase mass conservation equations. The thermohydraulic non-equilibrium is calculated by means of evaporation and condensation models. The mechanical non-equilibrium is modeled by a full-range drift-flux model. Also heat conduction in solid structures and heat exchange for the full spectrum of heat transfer regimes can be simulated. Test analyses of two-channel chilldown experiments and comparisons with the measured data have been performed.

Unit operations for gas-liquid mass transfer in reduced gravity environments

NASA Technical Reports Server (NTRS)

Pettit, Donald R.; Allen, David T.

1992-01-01

Basic scaling rules are derived for converting Earth-based designs of mass transfer equipment into designs for a reduced gravity environment. Three types of gas-liquid mass transfer operations are considered: bubble columns, spray towers, and packed columns. Application of the scaling rules reveals that the height of a bubble column in lunar- and Mars-based operations would be lower than terrestrial designs by factors of 0.64 and 0.79 respectively. The reduced gravity columns would have greater cross-sectional areas, however, by factors of 2.4 and 1.6 for lunar and Martian settings. Similar results were obtained for spray towers. In contract, packed column height was found to be nearly independent of gravity.

Flow of a surfactant across a thin liquid film wetting a solid substrate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peng, J.B.; He, S.X.; Dutta, P.

1989-12-15

Transfer of a monolayer (valinomycin) between two Langmuir troughs via an interconnecting glass bridge'' has been observed when there is a difference between the monolayer pressures in the two troughs. Assuming that the transfer occurs over the surface of the thin film of water that wets the bridge,'' the transfer rate can be used to estimate the thickness of the liquid film. The thickness thus determined may be used to determine the retarded van der Waals (Hamaker) constant associated with the interaction of the film with the underlying substrate.

Volatilization of ethylene dibromide from water

USGS Publications Warehouse

Rathbun, R.E.; Tai, D.Y.

1987-01-01

Overall mass-transfer coefficients for the volatilization of ethylene dibromide from water were measured simultaneously with the oxygen absorption coefficient in a laboratory stirred tank. Coefficients were measured as a function of mixing conditions in the water for two windspeeds. The ethylene dibromide mass-transfer coefficient depended on windspeed; the ethylene dibromide liquid-film coefficient did not, in agreement with theory. A constant relation existed between the liquid-film coefficients for ethylene dibromide and oxygen.

Quantification of VX Nerve Agent in Various Food Matrices by Solid-Phase Extraction Ultra-Performance Liquid ChromatographyTime-of-Flight Mass Spectrometry

DTIC Science & Technology

2016-04-01

QUANTIFICATION OF VX NERVE AGENT IN VARIOUS FOOD MATRICES BY SOLID-PHASE EXTRACTION ULTRA-PERFORMANCE...TITLE AND SUBTITLE Quantification of VX Nerve Agent in Various Food Matrices by Solid-Phase Extraction Ultra-Performance Liquid Chromatography... food matrices. The mixed-mode cation exchange (MCX) sorbent and Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) methods were used for

Gas Requirements in Pressurized Transfer of Liquid Hydrogen

NASA Technical Reports Server (NTRS)

Gluck, D. F.; Kline, J. F.

1961-01-01

Of late, liquid hydrogen has become a very popular fuel for space missions. It is being used in such programs as Centaur and Saturn. Furthermore, hydrogen is the ideal working fluid for nuclear powered space vehicles currently under development. In these applications, liquid hydrogen fuel is generally transferred to the combustion chamber by a combination of pumping and pressurization. The pump forces the liquid propellant from the fuel tank to the combustion chamber; gaseous pressurant holds tank pressure sufficiently high to prevent cavitation at the pump inlet and to maintain the structural rigidity of the tank. The pressurizing system, composed of pressurant, tankage, and associated hardware can be a large portion of the total vehicle weight. Pressurant weight can be reduced by introducing the pressurizing gas at temperatures substantially greater than those of liquid hydrogen. Heat and mass transfer processes thereby induced complicate gas requirements during discharge. These requirements must be known to insure proper design of the pressurizing system. The aim of this paper is to develop from basic mass and energy transfer processes a general method to predict helium and hydrogen gas usage for the pressurized transfer of liquid hydrogen. This required an analytical and experimental investigation, the results of which are described in this paper.

Physicochemical properties and solubility of alkyl-(2-hydroxyethyl)-dimethylammonium bromide.

PubMed

Domańska, Urszula; Bogel-Łukasik, Rafał

2005-06-23

Quaternary ammonium salts, which are precursors of ionic liquids, have been prepared from N,N-dimethylethanolamine as a substrate. The paper includes specific basic characterization of synthesized compounds via the following procedures: nuclear magnetic resonance (NMR) and Fourier transform infrared (FTIR) spectra, water content, mass spectroscopy (MS) spectra, temperatures of decompositions, basic thermodynamic properties of pure ionic liquids (the melting point, enthalpy of fusion, enthalpy of solid-solid phase transition, glass transition), and the difference in the solute heat capacity between the liquid and solid at the melting temperature determined by differential scanning calorimetry (DSC). The (solid + liquid) phase equilibria of binary mixtures containing (quaternary ammonium salt + water, or + 1-octanol) has been measured by a dynamic method over wide range of temperatures, from 230 K to 560 K. These data were correlated by means of the UNIQUAC ASM and modified nonrandom two-liquid NRTL1 equations utilizing parameters derived from the (solid + liquid) equilibrium. The partition coefficient of ionic liquid in the 1-octanol/water binary system has been calculated from the solubility results. Experimental partition coefficients (log P) were negative at three temperatures.

Determination of Aroclor 1260 in soil samples by gas chromatography with mass spectrometry and solid-phase microextraction.

PubMed

Zhang, Mengliang; Jackson, Glen P; Kruse, Natalie A; Bowman, Jennifer R; Harrington, Peter de B

2014-10-01

A novel fast screening method was developed for the determination of polychlorinated biphenyls that are constituents of the commercial mixture, Aroclor 1260, in soil matrices by gas chromatography with mass spectrometry combined with solid-phase microextraction. Nonequilibrium headspace solid-phase microextraction with a 100 μm polydimethylsiloxane fiber was used to extract polychlorinated biphenyls from 0.5 g of soil matrix. The use of 2 mL of saturated potassium dichromate in 6 M sulfuric acid solution improved the reproducibility of the extractions and the mass transfer of the polychlorinated biphenyls from the soil matrix to the microextraction fiber via the headspace. The extraction time was 30 min at 100°C. The percent recoveries, which were evaluated using an Aroclor 1260 standard and liquid injection, were within the range of 54.9-65.7%. Two-way extracted ion chromatogram data were used to construct calibration curves. The relative error was <±15% and the relative standard deviation was <15%, which are respective measures of the accuracy and precision. The method was validated with certified soil samples and the predicted concentrations for Aroclor 1260 agreed with the certified values. The method was demonstrated to be linear from 10 to 1000 ng/g for Aroclor 1260 in dry soil. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

On the roles of solid wall in the thermal analysis of micro heat pipes

NASA Astrophysics Data System (ADS)

Hung, Yew Mun

Micro heat pipe is a small-scale passive heat transfer device of very high thermal conductance that uses phase change and circulation of its working fluid to transfer thermal energy. Different from conventional heat pipe, a micro heat pipe does not contain any wick structure. In this thesis, a one-dimensional, steady-state mathematical model of a single triangular micro heat pipe is developed, with the main purpose of establishing a series of analytical studies on the roles of the solid wall of micro heat pipes in conjunction with the characterization of the thermal performance under the effects of various design and operational parameters. The energy equation of the solid wall is solved analytically to obtain the temperature distribution. The liquid phase is coupled with the solid wall through the continuity of heat flux at their interface, and the continuity, momentum and energy equations of the liquid and vapour phases, together with the Young-Laplace equation for capillary pressure, are solve numerically to yield the heat and fluid flow characteristics of the micro heat pipe. By coupling this mathematical model with the phase-change interfacial resistance model, the relationships for the axial temperature distributions of the liquid and vapour phases throughout the longitudinal direction of a micro heat pipe are also formulated. Four major aspects associated with the operational performance of micro heat pipes are discussed. Firstly, the investigation of the effects of axial conduction in the solid wall reveals that the presence of the solid wall induces change in the phase-change heat transport of the working fluid besides facilitating axial heat conduction in the solid wall. The analysis also highlights the effects of the thickness and thermal conductivity of the solid wall on the axial temperature distribution of solid wall, in the wake of the effects of the axial heat conduction induced on the phase-change heat transport of the working fluid. Secondly, analysis on thermal performance and physical phenomena of an overloaded micro heat pipes incorporating the effects of axial conduction in the solid wall is carried out. The thermal effects of the solid material are investigated and it is observed that the behaviour of the solid wall temperature distribution varies drastically as the applied heat load exceeds the heat transport capacity. The abrupt change in the temperature profile of an overloaded micro heat pipe is of considerable practical significance in which the occurrence of dryout can be identified by physically measuring the solid wall temperatures along the axial direction. Thirdly, by taking into account the axial conduction in the solid wall, the effect of gravity on the thermal performance of an inclined micro heat pipe is explored. Attributed to the occurrence of dryout, an abrupt temperature rise is observed at the evaporator end when the micro heat pipe is negatively inclined. Therefore, the orientation of a micro heat pipe can be determined by physically measuring the solid wall temperature. Lastly, by coupling the heat transfer model of phase-change phenomena at the liquid-vapour interface, the model with axial conduction in the solid wall of the micro heat pipe is extended to predict the axial liquid and vapour temperature distributions of the working fluid, which is useful for the verification of certain assumptions made in the derivation of the mathematical model besides for analyzing the heat transfer characteristics of the evaporation process.

Mathematical Analysis of the Solidification Behavior of Plain Steel Based on Solute- and Heat-Transfer Equations in the Liquid-Solid Zone

NASA Astrophysics Data System (ADS)

Fujimura, Toshio; Takeshita, Kunimasa; Suzuki, Ryosuke O.

2018-04-01

An analytical approximate solution to non-linear solute- and heat-transfer equations in the unsteady-state mushy zone of Fe-C plain steel has been obtained, assuming a linear relationship between the solid fraction and the temperature of the mushy zone. The heat transfer equations for both the solid and liquid zone along with the boundary conditions have been linked with the equations to solve the whole equations. The model predictions ( e.g., the solidification constants and the effective partition ratio) agree with the generally accepted values and with a separately performed numerical analysis. The solidus temperature predicted by the model is in the intermediate range of the reported formulas. The model and Neuman's solution are consistent in the low carbon range. A conventional numerical heat analysis ( i.e., an equivalent specific heat method using the solidus temperature predicted by the model) is consistent with the model predictions for Fe-C plain steels. The model presented herein simplifies the computations to solve the solute- and heat-transfer simultaneous equations while searching for a solidus temperature as a part of the solution. Thus, this model can reduce the complexity of analyses considering the heat- and solute-transfer phenomena in the mushy zone.

Numerical investigations on unstable direct contact condensation of cryogenic fluids

NASA Astrophysics Data System (ADS)

Jayachandran, K. N.; Arnab, Roy; Parthasarathi, Ghosh

2017-02-01

A typical problem of Direct Contact Condensation (DCC) occurs at the liquid oxygen (LOX) booster turbopump exit of oxidiser rich staged combustion cycle based semi-cryogenic rocket engines, where the hot gas mixture (predominantly oxygen and small amounts of combustion products) that runs the turbine mixes with LOX from the pump exit. This complex multiphase phenomena leads to the formation of solid CO2 & H2O, which is undesirable for the functioning of the main LOX turbopump. As a starting point for solving this complex problem, in this study, the hot gas mixture is taken as pure oxygen and hence, DCC of pure oxygen vapour jets in subcooled liquid oxygen is simulated using the commercial CFD package ANSYS CFX®. A two fluid model along with the thermal phase change model is employed for capturing the heat and mass transfer effects. The study mainly focuses on the subsonic DCC bubbling regime, which is reported as unstable with bubble formation, elongation, necking and collapsing effects. The heat transfer coefficients over a period of time have been computed and the various stages of bubbling have been analysed with the help of vapour volume fraction and pressure profiles. The results obtained for DCC of oxygen vapour-liquid mixtures is in qualitative agreement with the experimental results on DCC of steam-water mixtures.

Exploring bubble oscillation and mass transfer enhancement in acoustic-assisted liquid-liquid extraction with a microfluidic device

NASA Astrophysics Data System (ADS)

Xie, Yuliang; Chindam, Chandraprakash; Nama, Nitesh; Yang, Shikuan; Lu, Mengqian; Zhao, Yanhui; Mai, John D.; Costanzo, Francesco; Huang, Tony Jun

2015-07-01

We investigated bubble oscillation and its induced enhancement of mass transfer in a liquid-liquid extraction process with an acoustically-driven, bubble-based microfluidic device. The oscillation of individually trapped bubbles, of known sizes, in microchannels was studied at both a fixed frequency, and over a range of frequencies. Resonant frequencies were analytically identified and were found to be in agreement with the experimental observations. The acoustic streaming induced by the bubble oscillation was identified as the cause of this enhanced extraction. Experiments extracting Rhodanmine B from an aqueous phase (DI water) to an organic phase (1-octanol) were performed to determine the relationship between extraction efficiency and applied acoustic power. The enhanced efficiency in mass transport via these acoustic-energy-assisted processes was confirmed by comparisons against a pure diffusion-based process.

Effect of Drag Reducing Polymer and Suspended Solid on the Rate of Diffusion Controlled Corrosion in 90° Copper Elbow

NASA Astrophysics Data System (ADS)

Fouad, Mohamed Ahmed; Zewail, Taghreed Mohamed; Amine, Nieven Kamal Abbes

2017-06-01

Rate of diffusion controlled corrosion in 90° Copper Elbow acidified dichromate has been investigated in relation to the following parameters: effect of solution velocity in the absence and presence of drag- reducing polymer on the rate of diffusion controlled corrosion, and effect of the presence of suspended solids on the rate of diffusion controlled corrosion. It was found that the presence of drag reducing polymer inhibited the rate of mass transfer, while the presence of suspended solid increased significantly the rate of mass transfer.

Convective mass transfer around a dissolving bubble

NASA Astrophysics Data System (ADS)

Duplat, Jerome; Grandemange, Mathieu; Poulain, Cedric

2017-11-01

Heat or mass transfer around an evaporating drop or condensing vapor bubble is a complex issue due to the interplay between the substrate properties, diffusion- and convection-driven mass transfer, and Marangoni effects, to mention but a few. In order to disentangle these mechanisms, we focus here mainly on the convective mass transfer contribution in an isothermal mass transfer problem. For this, we study the case of a millimetric carbon dioxide bubble which is suspended under a substrate and dissolved into pure liquid water. The high solubility of CO2 in water makes the liquid denser and promotes a buoyant-driven flow at a high (solutal) Rayleigh number (Ra˜104 ). The alteration of p H allows the concentration field in the liquid to be imaged by laser fluorescence enabling us to measure both the global mass flux (bubble volume, contact angle) and local mass flux around the bubble along time. After a short period of mass diffusion, where the boundary layer thickens like the square root of time, convection starts and the CO2 is carried by a plume falling at constant velocity. The boundary layer thickness then reaches a plateau which depends on the bubble cross section. Meanwhile the plume velocity scales like (dV /d t )1 /2 with V being the volume of the bubble. As for the rate of volume loss, we recover a constant mass flux in the diffusion-driven regime followed by a decrease in the volume V like V2 /3 after convection has started. We present a model which agrees well with the bubble dynamics and discuss our results in the context of droplet evaporation, as well as high Rayleigh convection.

Amphiphilic phase-transforming catalysts for transesterification of triglycerides

NASA Astrophysics Data System (ADS)

Nawaratna, Gayan Ivantha

Heterogeneous catalytic reactions that involve immiscible liquid-phase reactants are challenging to conduct due to limitations associated with mass transport. Nevertheless, there are numerous reactions such as esterification, transesterification, etherification, and hydrolysis where two immiscible liquid reactants (such as polar and non-polar liquids) need to be brought into contact with a catalyst. With the intention of alleviating mass transport issues associated with such systems but affording the ability to separate the catalyst once the reaction is complete, the overall goal of this study is geared toward developing a catalyst that has emulsification properties as well as the ability to phase-transfer (from liquid-phase to solid-phase) while the reaction is ongoing and evaluating the effectiveness of such a catalytic process in a practical reaction. To elucidate this concept, the transesterification reaction was selected. Metal-alkoxides that possess acidic and basic properties (to catalyze the reaction), amphiphilic properties (to stabilize the alcohol/oil emulsion) and that can undergo condensation polymerization when heated (to separate as a solid subsequent to the completion of the reaction) were used to test the concept. Studies included elucidating the effect of metal sites and alkoxide sites and their concentration effects on transesterification reaction, effect of various metal alkoxide groups on the phase stability of the reactant system, and kinetic effects of the reaction system. The studies revealed that several transition-metal alkoxides, especially, titanium and yttrium based, responded positively to this reaction system. These alkoxides were able to be added to the reaction medium in liquid phase and were able to stabilize the alcohol/oil system. The alkoxides were selective to the transesterification reaction giving a range of ester yields (depending on the catalyst used). It was also observed that transition-metal alkoxides were able to be recovered in the form of their polymerized counterparts as a result of condensation polymerization subsequent to completion of the transesterification reaction.

Interfacial heat transfer in multiphase molten pools with gas injection

NASA Astrophysics Data System (ADS)

Bilbao Y Leon, Rosa Marina

1998-12-01

In the very unlikely event of a severe reactor accident involving core meltdown and pressure vessel failure, it is vital to identify the circumstances that would allow the molten core material to cool down and resolidify, bringing core debris to a safe and stable state. In this type of accident, the molten material which escapes from the reactor pressure vessel will accumulate as a molten pool in the reactor cavity below. To achieve coolability of the corium in this configuration it has been proposed to flood the cavity with water from above forming a layered structure where upward heat loss from the molten pool to the water will cause the core material to quench and solidify. The effectiveness of this procedure depends largely on the rate of upward heat loss as well as on the formation and stability of an upper crust. In this situation the molten pool becomes a three phase mixture: the solid and liquid slurry formed by the molten pool cooled to a temperature below the temperature of liquidus, agitated by the gases formed in the concrete ablation process. The present work quantifies the partition of the heat losses upward and downward considering the influence of the solid fraction in the pool and the viscosity effects, and the rate of heat loss through a solid layer. To complete this task a intermediate scale experimental test section has been designed and built at the University of Wisconsin - Madison, in which simulant materials are used to model the process of heat and mass transfer which involves the molten pool, the solid layer atop and the coolant layer above. The design includes volumetric heating, gas injection from the bottom and solids within the pool. New experimental results showing the heat transfer behavior for pools with different viscosities and various solid fractions are presented. The current results indicate a power split which favors heat transfer upward to the coolant simulant above by a 2:1 or 3:1 ratio. In addition, the power split is unaffected by the viscosity of the pool, the solid fractions in the pool and the superficial velocity.

Chemical-Specific Representation of Air-Soil Exchange and Soil Penetration in Regional Multimedia Models

DOE Office of Scientific and Technical Information (OSTI.GOV)

McKone, T.E.; Bennett, D.H.

2002-08-01

In multimedia mass-balance models, the soil compartment is an important sink as well as a conduit for transfers to vegetation and shallow groundwater. Here a novel approach for constructing soil transport algorithms for multimedia fate models is developed and evaluated. The resulting algorithms account for diffusion in gas and liquid components; advection in gas, liquid, or solid phases; and multiple transformation processes. They also provide an explicit quantification of the characteristic soil penetration depth. We construct a compartment model using three and four soil layers to replicate with high reliability the flux and mass distribution obtained from the exact analyticalmore » solution describing the transient dispersion, advection, and transformation of chemicals in soil with fixed properties and boundary conditions. Unlike the analytical solution, which requires fixed boundary conditions, the soil compartment algorithms can be dynamically linked to other compartments (air, vegetation, ground water, surface water) in multimedia fate models. We demonstrate and evaluate the performance of the algorithms in a model with applications to benzene, benzo(a)pyrene, MTBE, TCDD, and tritium.« less

Effect of internal pressure and gas/liquid interface area on the CO mass transfer coefficient using hollow fibre membranes as a high mass transfer gas diffusing system for microbial syngas fermentation.

PubMed

Yasin, Muhammad; Park, Shinyoung; Jeong, Yeseul; Lee, Eun Yeol; Lee, Jinwon; Chang, In Seop

2014-10-01

This study proposed a submerged hollow fibre membrane bioreactor (HFMBR) system capable of achieving high carbon monoxide (CO) mass transfer for applications in microbial synthesis gas conversion systems. Hydrophobic polyvinylidene fluoride (PVDF) membrane fibres were used to fabricate a membrane module, which was used for pressurising CO in water phase. Pressure through the hollow fibre lumen (P) and membrane surface area per unit working volume of the liquid (A(S)/V(L)) were used as controllable parameters to determine gas-liquid volumetric mass transfer coefficient (k(L)a) values. We found a k(L)a of 135.72 h(-1) when P was 93.76 kPa and AS/VL was fixed at 27.5m(-1). A higher k(L)a of 155.16 h(-1) was achieved by increasing AS/VL to 62.5m(-1) at a lower P of 37.23 kPa. Practicality of HFMBR to support microbial growth and organic product formation was assessed by CO/CO2 fermentation using Eubacterium limosum KIST612. Copyright © 2014 Elsevier Ltd. All rights reserved.

Commercial US transfer vehicle overview

NASA Astrophysics Data System (ADS)

Winchell, J. W.; Huss, R. L.

1986-10-01

A survey is presented of the design and operational status and intended or existing missions for apogee kick motors for launch from the Orbiter bay. Attention is also given to the associated hardware for interfacing and propelling the payloads from the bay. The PAM-D, -DII, and -A upper stage motors are described, with their payload boost capabilities of 1500-4300 lb to GEO. Features of the solid-fueled Transfer Orbit Stage, based on the IUS, and the liquid bipropellant-fueled Apogee and Maneuvering Stage, which can lift from 3000-5600 lb to GEO, respectively, are also delineated. The discussion also covers the liquid-fueled Leasat apogee motor, the solid-fueled GEO injection motor of the Shuttle Compatible Orbit Transfer Subsystem (4100-5900 lb), and the IUS (5000 lb) and Centaur (10,000 lb) systems. Government-industry cooperation to encourage the continued development of the industrial base to continue and expand production and use of upper stage vehicles is noted.

[Rapid identification of micro-constituents in monoammonium glycyrrhizinate raw materials by high-pressure solid phase extraction-high performance liquid chromatography-mass spectrometry].

PubMed

Yang, Xue-Dong; Tang, Xu-Yan; Sang, Lin

2012-11-01

To establish a method for rapid identification of micro-constituents in monoammonium glycyrrhizinate by high-pressure solid phase extraction-high performance liquid chromatography-mass spectrometry. HPLC preparative chromatograph was adopted for determining the optimal method for high-pressure solid phase extraction under optimal conditions. 5C18-MS-II column (20.0 mm x 20.0 mm) was used as the extraction column, with 35% acetonitrile-acetic acid solution (pH 2. 20) as eluent at the speed of 16 mL x min(-1). The sample size was 0.5 mL, and the extraction cycle was 4.5 min. Then, extract liquid was analyzed by high performance liquid chromatography-mass spectrometry (HPLC-MS) after being concentrated by 100 times. Under the optimal condition of high-pressure solid phase extraction-high performance liquid chromatography-mass spectrometry, 10 components were rapidly identified from monoammonium glycyrrhizinate raw materials. Among them, the chemical structures of six micro-constituents were identified as 3-O-[beta-D-glucuronopyranosyl-beta-D-glucuronopyranosyl]-30-0-beta-D-apiopyranosylglycyrrhetic/3-O- [P-D-glucuronopyranosyl-beta-D-glucuronopyranosyl]-30-O-beta-D-arabinopyranosylglycyrrhetic, glycyrrhizic saponin F3, 22-hydroxyglycyrrhizin/18alpha-glycyrrhizic saponin G2, 3-O-[beta-D-rhamnopyranosyl]-24-hydroxyglycyrrhizin, glycyrrhizic saponin J2, and glycyrrhizic saponin B2 by MS(n) spectra analysis and reference to literatures. Four main chemical components were identified as glycyrrhizic saponin G2, 18beta-glycyrrhizic acid, uralglycyrrhizic saponin B and 18alpha-glycyrrhizic acid by liquid chromatography, MS(n) and ultraviolet spectra information and comparison with reference substances. The method can be used to identify chemical constituents in monoammonium glycyrrhizinate quickly and effectively, without any reference substance, which provides basis for quality control and safe application of monoammonium glycyrrhizinate-related products.

GFSSP Training Course Lectures

NASA Technical Reports Server (NTRS)

Majumdar, Alok K.

2008-01-01

GFSSP has been extended to model conjugate heat transfer Fluid Solid Network Elements include: a) Fluid nodes and Flow Branches; b) Solid Nodes and Ambient Nodes; c) Conductors connecting Fluid-Solid, Solid-Solid and Solid-Ambient Nodes. Heat Conduction Equations are solved simultaneously with Fluid Conservation Equations for Mass, Momentum, Energy and Equation of State. The extended code was verified by comparing with analytical solution for simple conduction-convection problem The code was applied to model: a) Pressurization of Cryogenic Tank; b) Freezing and Thawing of Metal; c) Chilldown of Cryogenic Transfer Line; d) Boil-off from Cryogenic Tank.

Dendronization-induced phase-transfer, stabilization and self-assembly of large colloidal Au nanoparticles

NASA Astrophysics Data System (ADS)

Malassis, Ludivine; Jishkariani, Davit; Murray, Christopher B.; Donnio, Bertrand

2016-07-01

The phase-transfer of CTAB-coated aqueous, spherical gold nanoparticles, with metallic core diameters ranging from ca. 27 to 54 nm, into organic solvents by exchanging the primitive polar bilayer with lipophilic, disulfide dendritic ligands is reported. The presence of such a thick nonpolar organic shell around these large nanoparticles enhances their stabilization against aggregation, in addition to enabling their transfer into a variety of solvents such as chloroform, toluene or tetrahydrofuran. Upon the slow evaporation of a chloroform suspension deposited on a solid support, the dendronized hybrids were found to self-assemble into ring structures of various diameters. Moreover, their self-assembly at the liquid-air interface affords the formation of fairly long-range ordered monolayers, over large areas, that can then be entirely transferred onto solid substrates.The phase-transfer of CTAB-coated aqueous, spherical gold nanoparticles, with metallic core diameters ranging from ca. 27 to 54 nm, into organic solvents by exchanging the primitive polar bilayer with lipophilic, disulfide dendritic ligands is reported. The presence of such a thick nonpolar organic shell around these large nanoparticles enhances their stabilization against aggregation, in addition to enabling their transfer into a variety of solvents such as chloroform, toluene or tetrahydrofuran. Upon the slow evaporation of a chloroform suspension deposited on a solid support, the dendronized hybrids were found to self-assemble into ring structures of various diameters. Moreover, their self-assembly at the liquid-air interface affords the formation of fairly long-range ordered monolayers, over large areas, that can then be entirely transferred onto solid substrates. Electronic supplementary information (ESI) available: TEM microscope images. See DOI: 10.1039/c6nr03404g

Ultrasound/microwave-assisted solid-liquid-solid dispersive extraction with high-performance liquid chromatography coupled to tandem mass spectrometry for the determination of neonicotinoid insecticides in Dendrobium officinale.

PubMed

Zheng, Shuilian; Wu, Huizhen; Li, Zuguang; Wang, Jianmei; Zhang, Hu; Qian, Mingrong

2015-01-01

A one-step ultrasound/microwave-assisted solid-liquid-solid dispersive extraction procedure was used for the simultaneous determination of eight neonicotinoids (dinotefuran, nitenpyram, thiamethoxam, clothianidin, imidacloprid, acetamiprid, thiacloprid, imidaclothiz) in dried Dendrobium officinale by liquid chromatography combined with electrospray ionization triple quadrupole tandem mass spectrometry in multiple reaction monitoring mode. The samples were quickly extracted by acetonitrile and cleaned up by the mixed dispersing sorbents including primary secondary amine, C18 , and carbon-GCB. Parameters that could influence the ultrasound/microwave-assisted extraction efficiency such as microwave irradiation power, ultrasound irradiation power, temperature, and solvent were investigated. Recovery studies were performing well (70.4-113.7%) at three examined spiking levels (10, 50, and 100 μg/kg). Meanwhile, the limits of quantification for the neonicotinoids ranged from 0.87 to 1.92 μg/kg. The method showed good linearity in the concentration range of 1-100 μg/L with correlation coefficients >0.99. This quick and useful analytical method could provide a basis for monitoring neonicotinoid insecticide residues in herbs. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Rho-Isp Revisited and Basic Stage Mass Estimating for Launch Vehicle Conceptual Sizing Studies

NASA Technical Reports Server (NTRS)

Kibbey, Timothy P.

2015-01-01

The ideal rocket equation is manipulated to demonstrate the essential link between propellant density and specific impulse as the two primary stage performance drivers for a launch vehicle. This is illustrated by examining volume-limited stages such as first stages and boosters. This proves to be a good approximation for first-order or Phase A vehicle design studies for solid rocket motors and for liquid stages, except when comparing to hydrogen-fueled stages. A next-order mass model is developed that is able to model the mass differences between hydrogen-fueled and other stages. Propellants considered range in density from liquid methane to inhibited red fuming nitric acid. Calculated comparisons are shown for solid rocket boosters, liquid first stages, liquid upper stages, and a balloon-deployed single-stage-to-orbit concept. The derived relationships are ripe for inclusion in a multi-stage design space exploration and optimization algorithm, as well as for single-parameter comparisons such as those shown herein.

Rheology and hydrodynamic properties of Tolypocladium inflatum fermentation broth and its simulation.

PubMed

Benchapattarapong, N; Anderson, W A; Bai, F; Moo-Young, M

2005-07-01

A physico-chemical, two phase simulated pseudoplastic fermentation (SPF) broth was investigated in which Solka Floc cellulose fibre was used to simulate the filamentous biomass, and a mixture of 0.1% (w/v) carboxymethyl cellulose (CMC) and 0.15 M aqueous sodium chloride was used to simulate the liquid fraction of the fermentation broth. An investigation of the rheological behaviour and hydrodynamic properties of the SPF broth was carried out, and compared to both a fungal Tolypocladium inflatum fermentation broth and a CMC solution in a 50 L stirred tank bioreactor equipped with conventional Rushton turbines. The experimental data confirmed the ability of the two phase SPF broth to mimic both the T. inflatum broth bulk rheology as well as the mixing and mass transfer behaviour. In contrast, using a homogeneous CMC solution with a similar bulk rheology to simulate the fermentation resulted in a significant underestimation of the mass transfer and mixing times. The presence of the solid phase and its microstructure in the SPF broth appear to play a significant role in gas holdup and bubble size, thus leading to the different behaviours. The SPF broth seems to be a more accurate simulation fluid that can be used to predict the bioreactor mixing and mass transfer performance in filamentous fermentations, in comparison with CMC solutions used in some previous studies.

MECHANISMS GOVERNING TRANSIENTS FROM THE BATCH INCINERATION OF LIQUID WASTES IN ROTARY KILNS

EPA Science Inventory

When "containerized" liquid wastes, bound on sorbents. are introduced into a rotary kiln in a batch mode, transient phenomena in-volving heat transfer into, and waste mass transfer out of, the sorbent can oromote the raoid release of waste vaoor into the kiln environment. This ra...

Nonstationary heat and mass transfer in the multilayer building construction with ventilation channels

NASA Astrophysics Data System (ADS)

Kharkov, N. S.

2017-11-01

Results of numerical modeling of the coupled nonstationary heat and mass transfer problem under conditions of a convective flow in facade system of a three-layer concrete panel for two different constructions (with ventilation channels and without) are presented. The positive effect of ventilation channels on the energy and humidity regime over a period of 12 months is shown. Used new method of replacement a solid zone (requiring specification of porosity and material structure, what complicates process of convergence of the solution) on quasi-solid in form of a multicomponent mixture (with restrictions on convection and mass fractions).

Photoswitching of glass transition temperatures of azobenzene-containing polymers induces reversible solid-to-liquid transitions.

PubMed

Zhou, Hongwei; Xue, Changguo; Weis, Philipp; Suzuki, Yasuhito; Huang, Shilin; Koynov, Kaloian; Auernhammer, Günter K; Berger, Rüdiger; Butt, Hans-Jürgen; Wu, Si

2017-02-01

The development of polymers with switchable glass transition temperatures (T g ) can address scientific challenges such as the healing of cracks in high-T g polymers and the processing of hard polymers at room temperature without using plasticizing solvents. Here, we demonstrate that light can switch the T g of azobenzene-containing polymers (azopolymers) and induce reversible solid-to-liquid transitions of the polymers. The azobenzene groups in the polymers exhibit reversible cis-trans photoisomerization abilities. Trans azopolymers are solids with T g above room temperature, whereas cis azopolymers are liquids with T g below room temperature. Because of the photoinduced solid-to-liquid transitions of these polymers, light can reduce the surface roughness of azopolymer films by almost 600%, repeatedly heal cracks in azopolymers, and control the adhesion of azopolymers for transfer printing. The photoswitching of T g provides a new strategy for designing healable polymers with high T g and allows for control over the mechanical properties of polymers with high spatiotemporal resolution.

Mass transfer effects in a gasification riser

DOE Office of Scientific and Technical Information (OSTI.GOV)

Breault, Ronald W.; Li, Tingwen; Nicoletti, Phillip

2013-07-01

In the development of multiphase reacting computational fluid dynamics (CFD) codes, a number of simplifications were incorporated into the codes and models. One of these simplifications was the use of a simplistic mass transfer correlation for the faster reactions and omission of mass transfer effects completely on the moderate speed and slow speed reactions such as those in a fluidized bed gasifier. Another problem that has propagated is that the mass transfer correlation used in the codes is not universal and is being used far from its developed bubbling fluidized bed regime when applied to circulating fluidized bed (CFB) risermore » reactors. These problems are true for the major CFD codes. To alleviate this problem, a mechanistic based mass transfer coefficient algorithm has been developed based upon an earlier work by Breault et al. This fundamental approach uses the local hydrodynamics to predict a local, time varying mass transfer coefficient. The predicted mass transfer coefficients and the corresponding Sherwood numbers agree well with literature data and are typically about an order of magnitude lower than the correlation noted above. The incorporation of the new mass transfer model gives the expected behavior for all the gasification reactions evaluated in the paper. At the expected and typical design values for the solid flow rate in a CFB riser gasifier an ANOVA analysis has shown the predictions from the new code to be significantly different from the original code predictions. The new algorithm should be used such that the conversions are not over predicted. Additionally, its behaviors with changes in solid flow rate are consistent with the changes in the hydrodynamics.« less

40 CFR 98.166 - Data reporting requirements.

Code of Federal Regulations, 2014 CFR

2014-07-01

... transferred off site in either gas, liquid, or solid forms, following the requirements of subpart PP of this... (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Hydrogen Production § 98.166 Data reporting requirements. In... production and its type (scf or kg of gaseous fuels and feedstocks, gallons or kg of liquid fuels and...

Three Questions about the Enceladus Plumes: Are Large Vapor Chambers Necessary? Do the Plumes Vary in Strength from Year to Year? Do Fractal Aggregates Fit the Brightness Data as Well as Solid Ice?

NASA Astrophysics Data System (ADS)

Ingersoll, A. P.; Nakajima, M.; Ewald, S.; Gao, P.

2015-12-01

Postberg et al (2009) argued that the observed plume activity requires large vapor chambers above the evaporating liquid (left figure). Here we argue that large vapor chambers are unnecessary, and that a liquid-filled crack 1 meter wide extending along the 500 km length of the tiger stripes would be an adequate source (right figure). We consider controlled boiling (companion paper by Nakajima and Ingersoll 2015AGU) regulated by friction between the gas and the walls. Postberg et al use formulas from Rayleigh-Benard convection, which we argue does not apply when bubbles are transferring their latent heat across the liquid-gas interface. We show that modest convection currents in the liquid (few cm/s) can supply energy to the boiling zone and prevent it from freezing. Hedman et al (2013) reported brightness variations with orbital phase, but they also reported that their 2005 observations were roughly 50% higher than the 2009 observations. Here we extend the observation period to 2015 (Ingersoll and Ewald 2015). Our analysis relies on ISS images whereas Hedman et al rely on VIMS near-IR images, which have 40 times lower resolution. We successfully separate the brightness of the plume from the E-ring background. Our earlier analysis of the particle size distribution (Ingersoll and Ewald 2011) allows us to correct for differences in scattering angle. We confirm a general decline in activity over the 10-year period, but we find hints of fluctuations on shorter time scales. Kempf (Cassini project science meeting, Jan 22, 2015) reported that the mass of particles in the plumes could be an order of magnitude less than that reported by Ingersoll and Ewald (2011). Kempf used in situ particle measurements by CDA, whereas I&E used brightness observations and the assumption that the particles are solid ice. Here we show (Gao et al 2015AGU) that fractal aggregates fit the brightness data just as well as solid ice, and are consistent with the lower mass reported by Kempf.

Exploring bubble oscillation and mass transfer enhancement in acoustic-assisted liquid-liquid extraction with a microfluidic device

PubMed Central

Xie, Yuliang; Chindam, Chandraprakash; Nama, Nitesh; Yang, Shikuan; Lu, Mengqian; Zhao, Yanhui; Mai, John D.; Costanzo, Francesco; Huang, Tony Jun

2015-01-01

We investigated bubble oscillation and its induced enhancement of mass transfer in a liquid-liquid extraction process with an acoustically-driven, bubble-based microfluidic device. The oscillation of individually trapped bubbles, of known sizes, in microchannels was studied at both a fixed frequency, and over a range of frequencies. Resonant frequencies were analytically identified and were found to be in agreement with the experimental observations. The acoustic streaming induced by the bubble oscillation was identified as the cause of this enhanced extraction. Experiments extracting Rhodanmine B from an aqueous phase (DI water) to an organic phase (1-octanol) were performed to determine the relationship between extraction efficiency and applied acoustic power. The enhanced efficiency in mass transport via these acoustic-energy-assisted processes was confirmed by comparisons against a pure diffusion-based process. PMID:26223474

An Assessment of the General Applicability of the Relationship Between Nucleation of CO Bubbles and Mass Transfer of Phosphorus in Liquid Iron Alloys

NASA Astrophysics Data System (ADS)

Gu, Kezhuan; Dogan, Neslihan; Coley, Kenneth S.

2018-06-01

The current paper seeks to demonstrate the general applicability of the authors' recently developed treatment of surface renewal during decarburization of Fe-C-S alloys and its effect on the mass transport of phosphorus in the metal phase. The proposed model employs a quantitative model of CO bubble nucleation in the metal to predict the rate of surface renewal, which can then in turn be used to predict the mass-transfer coefficient for phosphorus. A model of mixed transport control in the slag and metal phases was employed to investigate the dephosphorization kinetics between a liquid iron alloy and oxidizing slag. Based on previous studies of the mass-transfer coefficient of FeO in the slag, it was possible to separate the mass transfer coefficient of phosphorus in metal phase, km , from the overall mass-transfer coefficient k_{{o}} . Using this approach, km was investigated under a wide range of conditions and shown to be represented reasonably by the mechanism proposed. The mass-transfer model was tested against results from the literature over a wide range of conditions. The analysis showed that the FeO content in the slag, silicon in the metal and the experimental temperature have strong impact on, km , almost entirely because of their effect on decarburization behavior.

An Assessment of the General Applicability of the Relationship Between Nucleation of CO Bubbles and Mass Transfer of Phosphorus in Liquid Iron Alloys

NASA Astrophysics Data System (ADS)

Gu, Kezhuan; Dogan, Neslihan; Coley, Kenneth S.

2018-02-01

The current paper seeks to demonstrate the general applicability of the authors' recently developed treatment of surface renewal during decarburization of Fe-C-S alloys and its effect on the mass transport of phosphorus in the metal phase. The proposed model employs a quantitative model of CO bubble nucleation in the metal to predict the rate of surface renewal, which can then in turn be used to predict the mass-transfer coefficient for phosphorus. A model of mixed transport control in the slag and metal phases was employed to investigate the dephosphorization kinetics between a liquid iron alloy and oxidizing slag. Based on previous studies of the mass-transfer coefficient of FeO in the slag, it was possible to separate the mass transfer coefficient of phosphorus in metal phase, km , from the overall mass-transfer coefficient k_{{o}} . Using this approach, km was investigated under a wide range of conditions and shown to be represented reasonably by the mechanism proposed. The mass-transfer model was tested against results from the literature over a wide range of conditions. The analysis showed that the FeO content in the slag, silicon in the metal and the experimental temperature have strong impact on, km , almost entirely because of their effect on decarburization behavior.

Two-structured solid particle model for predicting and analyzing supercritical extraction performance.

PubMed

Samadi, Sara; Vaziri, Behrooz Mahmoodzadeh

2017-07-14

Solid extraction process, using the supercritical fluid, is a modern science and technology, which has come in vogue regarding its considerable advantages. In the present article, a new and comprehensive model is presented for predicting the performance and separation yield of the supercritical extraction process. The base of process modeling is partial differential mass balances. In the proposed model, the solid particles are considered twofold: (a) particles with intact structure, (b) particles with destructed structure. A distinct mass transfer coefficient has been used for extraction of each part of solid particles to express different extraction regimes and to evaluate the process accurately (internal mass transfer coefficient was used for the intact-structure particles and external mass transfer coefficient was employed for the destructed-structure particles). In order to evaluate and validate the proposed model, the obtained results from simulations were compared with two series of available experimental data for extraction of chamomile extract with supercritical carbon dioxide, which had an excellent agreement. This is indicative of high potentiality of the model in predicting the extraction process, precisely. In the following, the effect of major parameters on supercritical extraction process, like pressure, temperature, supercritical fluid flow rate, and the size of solid particles was evaluated. The model can be used as a superb starting point for scientific and experimental applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Lattice Boltzmann simulation of the gas-solid adsorption process in reconstructed random porous media.

PubMed

Zhou, L; Qu, Z G; Ding, T; Miao, J Y

2016-04-01

The gas-solid adsorption process in reconstructed random porous media is numerically studied with the lattice Boltzmann (LB) method at the pore scale with consideration of interparticle, interfacial, and intraparticle mass transfer performances. Adsorbent structures are reconstructed in two dimensions by employing the quartet structure generation set approach. To implement boundary conditions accurately, all the porous interfacial nodes are recognized and classified into 14 types using a proposed universal program called the boundary recognition and classification program. The multiple-relaxation-time LB model and single-relaxation-time LB model are adopted to simulate flow and mass transport, respectively. The interparticle, interfacial, and intraparticle mass transfer capacities are evaluated with the permeability factor and interparticle transfer coefficient, Langmuir adsorption kinetics, and the solid diffusion model, respectively. Adsorption processes are performed in two groups of adsorbent media with different porosities and particle sizes. External and internal mass transfer resistances govern the adsorption system. A large porosity leads to an early time for adsorption equilibrium because of the controlling factor of external resistance. External and internal resistances are dominant at small and large particle sizes, respectively. Particle size, under which the total resistance is minimum, ranges from 3 to 7 μm with the preset parameters. Pore-scale simulation clearly explains the effect of both external and internal mass transfer resistances. The present paper provides both theoretical and practical guidance for the design and optimization of adsorption systems.

Lattice Boltzmann simulation of the gas-solid adsorption process in reconstructed random porous media

NASA Astrophysics Data System (ADS)

Zhou, L.; Qu, Z. G.; Ding, T.; Miao, J. Y.

2016-04-01

The gas-solid adsorption process in reconstructed random porous media is numerically studied with the lattice Boltzmann (LB) method at the pore scale with consideration of interparticle, interfacial, and intraparticle mass transfer performances. Adsorbent structures are reconstructed in two dimensions by employing the quartet structure generation set approach. To implement boundary conditions accurately, all the porous interfacial nodes are recognized and classified into 14 types using a proposed universal program called the boundary recognition and classification program. The multiple-relaxation-time LB model and single-relaxation-time LB model are adopted to simulate flow and mass transport, respectively. The interparticle, interfacial, and intraparticle mass transfer capacities are evaluated with the permeability factor and interparticle transfer coefficient, Langmuir adsorption kinetics, and the solid diffusion model, respectively. Adsorption processes are performed in two groups of adsorbent media with different porosities and particle sizes. External and internal mass transfer resistances govern the adsorption system. A large porosity leads to an early time for adsorption equilibrium because of the controlling factor of external resistance. External and internal resistances are dominant at small and large particle sizes, respectively. Particle size, under which the total resistance is minimum, ranges from 3 to 7 μm with the preset parameters. Pore-scale simulation clearly explains the effect of both external and internal mass transfer resistances. The present paper provides both theoretical and practical guidance for the design and optimization of adsorption systems.

Residue analysis of sixty pesticides in red swamp crayfish using QuEChERS with high-performance liquid chromatography-tandem mass spectrometry

USDA-ARS?s Scientific Manuscript database

In this study, a multi-residue analytical method using QuEChERS extraction and dispersive solid-phase extraction (d-SPE) cleanup followed by high-performance liquid chromatography–tandem mass spectrometry (HPLC-MS/MS) was developed for rapid determination of 60 pesticide residues in whole crayfish a...

Drop mass transfer in a microfluidic chip compared to a centrifugal contactor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nemer, Martin B.; Roberts, Christine C.; Hughes, Lindsey G.

2014-06-13

A model system was developed for enabling a multiscale understanding of centrifugal-contactor liquid–liquid extraction.The system consisted of Nd(III) + xylenol orange in the aqueous phase buffered to pH =5.5 by KHP, and dodecane + thenoyltrifluroroacetone (HTTA) + tributyphosphate (TBP) in the organic phase. Diffusion constants were measured for neodymium in both the organic and aqueous phases, and the Nd(III) partition coefficients were measured at various HTTA and TBP concentrations. A microfluidic channel was used as a high-shear model environment to observe mass-transfer on a droplet scale with xylenol orange as the aqueous-phase metal indicator; mass-transfer rates were measured quantitatively inmore » both diffusion and reaction limited regimes on the droplet scale. Lastly, the microfluidic results were comparable to observations made for the same system in a laboratory scale liquid–liquid centrifugal contactor, indicating that single drop microfluidic experiments can provide information on mass transfer in complicated flows and geometries.« less

Cooling Particle-Coated Bubbles: Destabilization beyond Dissolution Arrest.

PubMed

Poulichet, Vincent; Garbin, Valeria

2015-11-10

Emulsions and foams that remain stable under varying environmental conditions are central in the food, personal care, and other formulated products industries. Foams stabilized by solid particles can provide longer-term stability than surfactant-stabilized foams. This stability is partly ascribed to the observation that solid particles can arrest bubble dissolution, which is driven by the Laplace pressure across the curved gas-liquid interface. We studied experimentally the effect of changes in temperature on the lifetime of particle-coated air microbubbles in water. We found that a decrease in temperature destabilizes particle-coated microbubbles beyond dissolution arrest. A quasi-steady model describing the effect of the change in temperature on mass transfer suggests that the dominant mechanism of destabilization is the increased solubility of the gas in the liquid, leading to a condition of undersaturation. Experiments at constant temperature confirmed that undersaturation alone can drive destabilization of particle-coated bubbles, even for vanishing Laplace pressure. We also found that dissolution of a particle-coated bubble can lead either to buckling of the coating or to gradual expulsion of particles, depending on the particle-to-bubble size ratio, with potential implications for controlled release.

Effect of nanostructure on rapid boiling of water on a hot copper plate: a molecular dynamics study

NASA Astrophysics Data System (ADS)

Fu, Ting; Mao, Yijin; Tang, Yong; Zhang, Yuwen; Yuan, Wei

2016-08-01

Molecular dynamic simulations are performed to study the effects of nanostructure on rapid boiling of water that is suddenly heated by a hot copper plate. The results show that the nanostructure has significant effects on energy transfer from solid copper plate to liquid water and phase change process from liquid water to vapor. The liquid water on the solid surface rapidly boil after contacting with an extremely hot copper plate and consequently a cluster of liquid water moves upward during phase change. The temperature of the water film when it separates from solid surface and its final temperature when the system is at equilibrium strongly depend on the size of the nanostructure. These temperatures increase with increasing size of nanostructure. Furthermore, a non-vaporized molecular layer is formed on the surface of the copper plate even continuous heat flux is passing into water domain through the plate.

Biomass drying in a pulsed fluidized bed without inert bed particles

DOE PAGES

Jia, Dening; Bi, Xiaotao; Lim, C. Jim; ...

2016-08-29

Batch drying was performed in the pulsed fluidized bed with various species of biomass particles as an indicator of gas–solid contact efficiency and mass transfer rate under different operating conditions including pulsation duty cycle and particle size distribution. The fluidization of cohesive biomass particles benefited from the shorter opening time of pulsed gas flow and increased peak pressure drop. The presence of fines enhanced gas–solid contact of large and irregular biomass particles, as well as the mass transfer efficiency. A drying model based on two-phase theory was proposed, from which effective diffusivity was calculated for various gas flow rates, temperaturemore » and pulsation frequency. Intricate relationship was discovered between pulsation frequency and effective diffusivity, as mass transfer was deeply connected with the hydrodynamics. Effective diffusivity was also found to be proportional to gas flow rate and drying temperature. In conclusion, operating near the natural frequency of the system also favored drying and mass transfer.« less

About Mass Transfer in Capillaries of Biological Systems under Influence of Vibrations

NASA Astrophysics Data System (ADS)

Prisniakov, K.

Vibrations accompany the flight of the manned spacecraft both at a stage of a orbital injection to an orbit, and during long flights (as noise), rendering undesirable physiological influence on crew, reducing serviceability and creating constant discomfort. The report represents attempt to predict a state of the cosmonaut in conditions of influence of vibrations for the period of start and stay in Space, being based on researches of mass transfer processes in capillary systems. For this purpose the original researches on heat and mass transfer processes with evaporation of liquids in capillary - porous structures in conditions of vibration actions and changes of a direction of action of gravitation are generalized. Report demonstrates the existence of modes at which increased or lowered mass transfer is achieved on border of separation "liquid - gas". The possible mechanism of influence of vibrations on evaporation of a liquid in capillaries is examined. The magnitudes of frequencies and amplitudes are submitted at which minimax characteristics are observed. The opportunity of application of the developed mathematical model of heat and mass transfer in capillary - porous structures to forecasting influence of vibrations for biological processes in capillaries of alive essences is analyzed. Such approach is justified on the mechanical nature of harmful influence of vibrations on an organism of the person. In addition the range of vibration frequencies which arise during space flights, corresponds to own resonant frequencies of a human body and his separate organs. Comparison of these resonant frequencies of a body of the person (5-80 Hertz) with vibration frequencies of optimum modes of heat and mass transfer in capillary - porous structures (20-40 Hertz) is shown their ranges of coverage. It gives the basis to assume existence of similar effects in capillaries of human body. It is supposed, that the difficulty of breath, change of a rhythm of breath, the subsequent weariness under vibration action are attributable to infringements of normal mass transfer between the inhaled air and blood. The opportunity of use of the received laws is discussed for assessment of influence of gravitational fields on intensity mass transfer in capillaries of biosystems also.

Heat-transfer resistance at solid-liquid interfaces: a tool for the detection of single-nucleotide polymorphisms in DNA.

PubMed

van Grinsven, Bart; Vanden Bon, Natalie; Strauven, Hannelore; Grieten, Lars; Murib, Mohammed; Monroy, Kathia L Jiménez; Janssens, Stoffel D; Haenen, Ken; Schöning, Michael J; Vermeeren, Veronique; Ameloot, Marcel; Michiels, Luc; Thoelen, Ronald; De Ceuninck, Ward; Wagner, Patrick

2012-03-27

In this article, we report on the heat-transfer resistance at interfaces as a novel, denaturation-based method to detect single-nucleotide polymorphisms in DNA. We observed that a molecular brush of double-stranded DNA grafted onto synthetic diamond surfaces does not notably affect the heat-transfer resistance at the solid-to-liquid interface. In contrast to this, molecular brushes of single-stranded DNA cause, surprisingly, a substantially higher heat-transfer resistance and behave like a thermally insulating layer. This effect can be utilized to identify ds-DNA melting temperatures via the switching from low- to high heat-transfer resistance. The melting temperatures identified with this method for different DNA duplexes (29 base pairs without and with built-in mutations) correlate nicely with data calculated by modeling. The method is fast, label-free (without the need for fluorescent or radioactive markers), allows for repetitive measurements, and can also be extended toward array formats. Reference measurements by confocal fluorescence microscopy and impedance spectroscopy confirm that the switching of heat-transfer resistance upon denaturation is indeed related to the thermal on-chip denaturation of DNA. © 2012 American Chemical Society

Methods to control phase inversions and enhance mass transfer in liquid-liquid dispersions

DOEpatents

Tsouris, Constantinos; Dong, Junhang

2002-01-01

The present invention is directed to the effects of applied electric fields on liquid-liquid dispersions. In general, the present invention is directed to the control of phase inversions in liquid-liquid dispersions. Because of polarization and deformation effects, coalescence of aqueous drops is facilitated by the application of electric fields. As a result, with an increase in the applied voltage, the ambivalence region is narrowed and shifted toward higher volume fractions of the dispersed phase. This permits the invention to be used to ensure that the aqueous phase remains continuous, even at a high volume fraction of the organic phase. Additionally, the volume fraction of the organic phase may be increased without causing phase inversion, and may be used to correct a phase inversion which has already occurred. Finally, the invention may be used to enhance mass transfer rates from one phase to another through the use of phase inversions.

Vented Chill / No-Vent Fill of Cryogenic Propellant Tanks

NASA Technical Reports Server (NTRS)

Rhys, Noah O.; Foster, Lee W.; Martin, Adam K.; Stephens, Jonathan R.

2016-01-01

Architectures for extended duration missions often include an on-orbit replenishment of the space vehicle's cryogenic liquid propellants. Such a replenishment could be accomplished via a tank-to-tank transfer from a dedicated tanker or a more permanent propellant depot storage tank. Minimizing the propellant loss associated with transfer line and receiver propellant tank thermal conditioning is essential for mass savings. A new methodology for conducting tank-to-tank transfer while minimizing such losses has been demonstrated. Charge-Hold-Vent is the traditional methodology for conducting a tank-to-tank propellant transfer. A small amount of cryogenic liquid is introduced to chill the transfer line and propellant tank. As the propellant absorbs heat and undergoes a phase change, the tank internal pressure increases. The tank is then vented to relieve pressure prior to another charge of cryogenic liquid being introduced. This cycle is repeated until the transfer lines and tank are sufficiently chilled and the replenishment of the propellant tank is complete. This method suffers inefficiencies due to multiple chill and vent cycles within the transfer lines and associated feed system components. Additionally, this system requires precise measuring of cryogenic fluid delivery for each transfer, multiple valve cycling events, and other complexities associated with cycled operations. To minimize propellant loss and greatly simplify on-orbit operations, an alternate methodology has been designed and demonstrated. The Vented Chill / No Vent Fill method is a simpler, constant flow approach in which the propellant tank and transfer lines are only chilled once. The receiver tank is continuously vented as cryogenic liquid chills the transfer lines, tank mass and ullage space. Once chilled sufficiently, the receiver tank valve is closed and the tank is completely filled. Interestingly, the vent valve can be closed prior to receiver tank components reaching liquid saturation temperature. An incomplete fill results if insufficient energy is removed from the tank's thermal mass and ullage space. The key to successfully conducting the no vent fill is to assure that sufficient energy is removed from the system prior to closing the receiver tank vent valve. This paper will provide a description of the transfer methodology and test article, and will provide a discussion of test results.

Simultaneous heat and mass transfer inside a vertical channel in evaporating a heated falling glycols liquid film

NASA Astrophysics Data System (ADS)

Nait Alla, Abderrahman; Feddaoui, M'barek; Meftah, Hicham

2015-12-01

The interactive effects of heat and mass transfer in the evaporation of ethylene and propylene glycol flowing as falling films on vertical channel was investigated. The liquid film falls along a left plate which is externally subjected to a uniform heat flux while the right plate is the dry wall and is kept thermally insulated. The model solves the coupled governing equations in both phases together with the boundary and interfacial conditions. The systems of equations obtained by using an implicit finite difference method are solved by Tridiagonal Matrix Algorithm. The influence of the inlet liquid flow, Reynolds number in the gas flow and the wall heat flux on the intensity of heat and mass transfers are examined. A comparison between the results obtained for studied glycols and water in the same conditions is made. The results indicate that water evaporates in more intense way in comparison to glycols and the increase of gas flow rate tends to improve slightly the evaporation.

Absorption degree analysis on biogas separation with ionic liquid systems.

PubMed

Zhang, Xin; Zhang, Suojiang; Bao, Di; Huang, Ying; Zhang, Xiangping

2015-01-01

For biogas upgrading, present work mainly focuses on either thermodynamics or mass transfer properties. A systematical study on these two aspects is important for developing a new biogas separation process. In this work, a new criterion "absorption degree", which combines both thermodynamics and mass transfer properties, was proposed for the first time to comprehensively evaluate the absorption performance. Henry's law constants of CO2 and CH4 in ionic liquids-polyethylene glycol dimethyl ethers mixtures were investigated. The liquid-side mass transfer coefficients (kL) were determined. The results indicate that IL-NHD mixtures exhibit not only a high CO2/CH4 selectivity, but also a fast kL for CO2 absorption. The [bmim][NO3]+NHD mixtures present a high absorption degree value for CO2 but a low value for CH4. For presenting a highest relative absorption degree value, the 50wt% [bmim][NO3]+50wt% NHD mixture is recommended for biogas upgrading. Copyright © 2014 Elsevier Ltd. All rights reserved.

Some Fundamental Experiments on Apparent Dissolution Rate of Gas Phase in the Groundwater Recovery Processes of the Geological Disposal System - 12146

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yoshii, Taiki; Niibori, Yuichi; Mimura, Hitoshi

The apparent dissolution rates of gas phase in the co-presence of solid phase were examined by in-room experiments in this study. The apparent dissolution rate of gas phase q (mol/m{sup 3}.s) was generally defined by q=aK{sub L}(γP{sub g}-c), where a (1/m) is specific surface area of the interface between gas and liquid phases, K{sub L} (m/s) is overall mass transfer coefficient, γ (mol/(Pa.m{sup 3})) is reciprocal number of Henry constant, P{sub g} (Pa) is partial pressure of gas phase, and c (mol/m{sup 3}) is the concentration of gas component in liquid phase. As a model gas, CO{sub 2} gas wasmore » used. For evaluating the values of K{sub L}, this study monitored pH or the migration rate of the interface between water/gas phases, using some experiments such as the packed beds and the micro channel consisting of granite chip and rubber sheet including a slit. In the results, the values of K{sub L} were distributed in the range from 5.0x10{sup -6} m/s to 5.0x10{sup -7} m/s. These values were small, in comparison with that (7.8x10{sup -4} m/s) obtained from the bubbling test where gas phase was continually injected into deionized water without solid phase. This means that the solid phase limits the local mixing of water phase near gas-liquid interfaces. (authors)« less

Computational Fluid Dynamics–Discrete Element Method (CFD-DEM) Study of Mass-Transfer Mechanisms in Riser Flow

PubMed Central

2017-01-01

We report a computational fluid dynamics–discrete element method (CFD-DEM) simulation study on the interplay between mass transfer and a heterogeneous catalyzed chemical reaction in cocurrent gas-particle flows as encountered in risers. Slip velocity, axial gas dispersion, gas bypassing, and particle mixing phenomena have been evaluated under riser flow conditions to study the complex system behavior in detail. The most important factors are found to be directly related to particle cluster formation. Low air-to-solids flux ratios lead to more heterogeneous systems, where the cluster formation is more pronounced and mass transfer more influenced. Falling clusters can be partially circumvented by the gas phase, which therefore does not fully interact with the cluster particles, leading to poor gas–solid contact efficiencies. Cluster gas–solid contact efficiencies are quantified at several gas superficial velocities, reaction rates, and dilution factors in order to gain more insight regarding the influence of clustering phenomena on the performance of riser reactors. PMID:28553011

Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) Study of Mass-Transfer Mechanisms in Riser Flow.

PubMed

Carlos Varas, Álvaro E; Peters, E A J F; Kuipers, J A M

2017-05-17

We report a computational fluid dynamics-discrete element method (CFD-DEM) simulation study on the interplay between mass transfer and a heterogeneous catalyzed chemical reaction in cocurrent gas-particle flows as encountered in risers. Slip velocity, axial gas dispersion, gas bypassing, and particle mixing phenomena have been evaluated under riser flow conditions to study the complex system behavior in detail. The most important factors are found to be directly related to particle cluster formation. Low air-to-solids flux ratios lead to more heterogeneous systems, where the cluster formation is more pronounced and mass transfer more influenced. Falling clusters can be partially circumvented by the gas phase, which therefore does not fully interact with the cluster particles, leading to poor gas-solid contact efficiencies. Cluster gas-solid contact efficiencies are quantified at several gas superficial velocities, reaction rates, and dilution factors in order to gain more insight regarding the influence of clustering phenomena on the performance of riser reactors.

Drop-on-demand sample introduction system coupled with the flowing atmospheric-pressure afterglow for direct molecular analysis of complex liquid micro-volume samples

PubMed Central

Schaper, J. Niklas; Pfeuffer, Kevin P.; Shelley, Jacob T.; Bings, Nicolas H.

2012-01-01

One of the fastest developing fields in analytical spectrochemistry in recent years is ambient desorption/ionization mass spectrometry (ADI-MS). This burgeoning interest has been due to the demonstrated advantages of the method: simple mass spectra, little or no sample preparation, and applicability to samples in the solid, liquid, or gaseous state. One such ADI-MS source, the flowing atmospheric-pressure afterglow (FAPA), is capable of direct analysis of solids just by aiming the source at the solid surface and sampling the produced ions into a mass spectrometer. However, direct introduction of significant volumes of liquid samples into this source has not been possible, as solvent loads can quench the afterglow and, thus, the formation of reagent ions. As a result, the analysis of liquid samples is preferably carried out by analyzing dried residues or by desorbing small amounts of liquid samples directly from the liquid surface. In the former case, reproducibility of sample introduction is crucial if quantitative results are desired. In the present study, introduction of liquid samples as very small droplets helps overcome the issues of sample positioning and reduced levels of solvent intake. A recently developed “drop-on-demand” (DOD) aerosol generator is capable of reproducibly producing very small volumes of liquid (~17 pL). In this paper, the coupling of FAPA-MS and DOD is reported and applications are suggested. Analytes representing different classes of substances were tested and limits of detections were determined. Matrix tolerance was investigated for drugs of abuse and their metabolites by analyzing raw urine samples and quantification without the use of internal standards. Limits of detection below 2 µg/mL, without sample pretreatment, were obtained. PMID:23025277

Drop-on-demand sample introduction system coupled with the flowing atmospheric-pressure afterglow for direct molecular analysis of complex liquid microvolume samples.

PubMed

Schaper, J Niklas; Pfeuffer, Kevin P; Shelley, Jacob T; Bings, Nicolas H; Hieftje, Gary M

2012-11-06

One of the fastest developing fields in analytical spectrochemistry in recent years is ambient desorption/ionization mass spectrometry (ADI-MS). This burgeoning interest has been due to the demonstrated advantages of the method: simple mass spectra, little or no sample preparation, and applicability to samples in the solid, liquid, or gaseous state. One such ADI-MS source, the flowing atmospheric-pressure afterglow (FAPA), is capable of direct analysis of solids just by aiming the source at the solid surface and sampling the produced ions into a mass spectrometer. However, direct introduction of significant volumes of liquid samples into this source has not been possible, as solvent loads can quench the afterglow and, thus, the formation of reagent ions. As a result, the analysis of liquid samples is preferably carried out by analyzing dried residues or by desorbing small amounts of liquid samples directly from the liquid surface. In the former case, reproducibility of sample introduction is crucial if quantitative results are desired. In the present study, introduction of liquid samples as very small droplets helps overcome the issues of sample positioning and reduced levels of solvent intake. A recently developed "drop-on-demand" (DOD) aerosol generator is capable of reproducibly producing very small volumes of liquid (∼17 pL). In this paper, the coupling of FAPA-MS and DOD is reported and applications are suggested. Analytes representing different classes of substances were tested and limits of detections were determined. Matrix tolerance was investigated for drugs of abuse and their metabolites by analyzing raw urine samples and quantification without the use of internal standards. Limits of detection below 2 μg/mL, without sample pretreatment, were obtained.

A gravity independent biological grey water treatment system for space applications

NASA Astrophysics Data System (ADS)

Nashashibi, Majda'midhat

2002-09-01

Biological treatment of grey water in space presents serious challenges, stemming mainly from microgravity conditions. The major concerns are phase separation and mass transfer limitations. To overcome solid-liquid phase separation, novel immobilized cell packed bed (ICPB) bioreactors have been developed to treat synthetic grey water. Packed bed bioreactors provide a unique environment for attached microbial growth resulting in high biomass concentrations, which greatly enhance process efficiency with substantial reductions in treatment time and reactor volume. To overcome the gas-liquid phase separation and mass transfer limitations, an oxygenation module equipped with tubular membranes has been developed to deliver bubble-less oxygen under pressure. The selected silicone membranes are hydrophobic, non-porous and oxygen selective. Oxygen dissolves in the walls of the membranes and then diffuses into the water without forming bubbles. Elevated pressures maintain all gaseous by-products in solution and provide high dissolved oxygen concentrations within the system. The packing media are lightweight, inexpensive polyethylene terephthalate (PET) flakes that have large specific surface area, act as a filter for solids and yield highly tortuous flow paths thereby increasing the contact time between the biomass and contaminants. Tests on both pressurized and ambient pressure ICPB bioreactors revealed organic carbon removal efficiencies over 90%. Despite the high ammonia level in the influent, nitrification occured in both the ambient pressure and pressurized nitrification bioreactors at efficiencies of 80% and 60%, respectively. Biomass yield was approximately 0.20 g volatile suspended solids per gram of grey water-COD processed in the pressurized bioreactor. The biomass yield of such novel aerobic ICPB systems is comparable to that of anaerobic processes. These efficient systems produce minimal amounts of biomass compared to other aerobic processes, making them less prone to clogging under long operation periods. The effluent contains low concentration of suspended solids, thus further phase separation may not be necessary. The maintenance requirements are minimal, thereby reducing labor time. The bioreactors could sustain loading and pressure shocks with rapid recovery. An empirical model has been developed for design and scale-up of the pressurized bioreactor for organic carbon and nitrogen conversions. NASA-Johnson Space Center adopted the nitrification bioreactor for prototype testing and potential future use in long duration human space missions.

Release profiles of phenytoin from new oral dosage form for the elderly.

PubMed

Watanabe, A; Hanawa, T; Sugihara, M; Yamamoto, K

1994-08-01

Utilization of the solid mass containing phenytoin, sodium caseinate and microcrystalline cellulose (MCC) as a new dosage form for the elderly was studied. The solid mass was prepared by treatment of the powder mixture with high pressure steam at 115 degrees C for 10 min. The stability of phenytoin in the solid mass was confirmed by infrared spectroscopy and high performance liquid chromatography. The extent of swelling of the solid mass containing phenytoin was investigated by water absorption test and gel strength test, and the swelling property was almost independent of the presence of phenytoin. The release profile of phenytoin from the solid mass was determined under various conditions, and was found to be influenced by the extent of swelling and the swollen state. It was observed that the protein adsorption to the phenytoin crystal surface and the addition of digestive enzyme also affected the release profile. In water, the solid mass prepared from a ground mixture of phenytoin and MCC showed remarkable improvement of release profile of phenytoin.

CFD studies on biomass thermochemical conversion.

PubMed

Wang, Yiqun; Yan, Lifeng

2008-06-01

Thermochemical conversion of biomass offers an efficient and economically process to provide gaseous, liquid and solid fuels and prepare chemicals derived from biomass. Computational fluid dynamic (CFD) modeling applications on biomass thermochemical processes help to optimize the design and operation of thermochemical reactors. Recent progression in numerical techniques and computing efficacy has advanced CFD as a widely used approach to provide efficient design solutions in industry. This paper introduces the fundamentals involved in developing a CFD solution. Mathematical equations governing the fluid flow, heat and mass transfer and chemical reactions in thermochemical systems are described and sub-models for individual processes are presented. It provides a review of various applications of CFD in the biomass thermochemical process field.

CFD Studies on Biomass Thermochemical Conversion

PubMed Central

Wang, Yiqun; Yan, Lifeng

2008-01-01

Thermochemical conversion of biomass offers an efficient and economically process to provide gaseous, liquid and solid fuels and prepare chemicals derived from biomass. Computational fluid dynamic (CFD) modeling applications on biomass thermochemical processes help to optimize the design and operation of thermochemical reactors. Recent progression in numerical techniques and computing efficacy has advanced CFD as a widely used approach to provide efficient design solutions in industry. This paper introduces the fundamentals involved in developing a CFD solution. Mathematical equations governing the fluid flow, heat and mass transfer and chemical reactions in thermochemical systems are described and sub-models for individual processes are presented. It provides a review of various applications of CFD in the biomass thermochemical process field. PMID:19325848

Simulation Studies on Cooling of Cryogenic Propellant by Gas Bubbling

NASA Astrophysics Data System (ADS)

Sandilya, Pavitra; Saha, Pritam; Sengupta, Sonali

Injection cooling was proposed to store cryogenic liquids (Larsen et al. [1], Schmidt [2]). When a non-condensable gas is injected through a liquid, the liquid component would evaporate into the bubble if its partial pressure in the bubble is lower than its vapour pressure. This would tend to cool the liquid. Earlier works on injection cooling was analysed by Larsen et al. [1], Schmidt [2], Cho et al. [3] and Jung et al. [4], considering instantaneous mass transfer and finite heat transfer between gas bubble and liquid. It is felt that bubble dynamics (break up, coalescence, deformation, trajectory etc.) should also play a significant role in liquid cooling. The reported work are based on simple assumptions like single bubble, zero bubble deformation, and no inter-bubble interactions. Hence in this work, we propose a lumped parameter model considering both heat and mass interactions between bubble and the liquid to gain a preliminary insight into the cooling phenomenon during gas injection through a liquid.

The effect of surface movements on nitrogen mass transfer in liquid iron

NASA Astrophysics Data System (ADS)

Hirashima, N.; Choo, R. T. C.; Toguri, J. M.; Mukai, K.

1995-10-01

Marangoni convection due to surface tension gradients set up in a nitrogen-liquid iron system at 1873 K has been mathematically simulated and experimentally confirmed by measuring the rate of nitrogen absorption into liquid iron and by observing the free surface motion of liquid iron via zirconium oxide particles using X-ray radiography. This surface flow was created by blowing nitrogen gas through a small lance over the free surface of the liquid iron contained in an alumina boat under resistance heating. Absorption measurements indicated that the mass-transfer coefficient of nitrogen in liquid iron due to Marangoni convection ( k {m/1}>=1.5×10-4 m/s) is slightly less than that due to induction stirring ( k {m/1}=2.1×10-4 to 1.5×10-4 m/s). The free surface velocity induced by the surface tension gradient, with an initial composition difference of 425 to 10 ppm, was found to be of the order of 0.05 to 0.11 m/s. Mathematical modeling was also carried out to determine the velocity and nitrogen concentration profiles in the alumina boat. It was found that Marangoni convection creates mildly turbulent flows in liquid iron. Good agreements between the experimentally obtained data (nitrogen concentration and surface velocity) and the computed results were attained when a constant eddy viscosity which was five times the molecular value was assumed. This prescription allows both the predicted apparent mass-transfer coefficient and the predicted surface velocity to match the experimental results simultaneously. Note that the transport coefficients in the momentum and the convective-diffusive equations are correlated by the turbulent Schmidt number. The dimensionless mass-transfer correlation obtained for the present N-Fe system at 1873 K under resistance heating was found to be Sh=0.104 Re0.7·Sc0.7 with Sc=79.5 (3500

GAS SEAL

DOEpatents

Monson, H.; Hutter, E.

1961-07-11

A seal is described for a cover closing an opening in the top of a pressure vessel that may house a nuclear reactor. The seal comprises a U-shaped trough formed on the pressure vessel around the opening therein, a mass of metal in the trough, and an edge flange on the cover extending loosely into the trough and dipping into the metal mass. The lower portion of the metal mass is kept melted, and the upper portion, solid. The solid pontion of the metal mass prevents pressure surges in the vessel from expelling the liquid portion of the metal mass from the trough; the liquld portion, thus held in place by the solid portion, does not allow gas to go through, and so gas cannot escape through shrinkage holes in the solid portion.

An effective device for gas-liquid oxygen removal in enclosed microalgae culture.

PubMed

Su, Zhenfeng; Kang, Ruijuan; Shi, Shaoyuan; Cong, Wei; Cai, Zhaoling

2010-01-01

A high-performance gas-liquid transmission device (HPTD) was described in this paper. To investigate the HPTD mass transfer characteristics, the overall volumetric mass transfer coefficients, K(A)(La,CO(2)) for the absorption of gaseous CO(2) and K(A)(La,O(2)) for the desorption of dissolved O(2) were determined, respectively, by titration and dissolved oxygen electrode. The mass transfer capability of carbon dioxide was compared with that of dissolved oxygen in the device, and the operating conditions were optimized to suit for the large-scale enclosed micro-algae cultivation. Based on the effectiveness evaluation of the HPTD applied in one enclosed flat plate Spirulina culture system, it was confirmed that the HPTD can satisfy the demand of the enclosed system for carbon supplement and excessive oxygen removal.

[Determination of fatty acid esters of chloropropanediols in diet samples by gas chromatography-mass spectrometry coupled with solid-supported liquid-liquid extraction].

PubMed

Gao, Jie; Liu, Qing; Han, Feng; Miao, Hong; Zhao, Yunfeng; Wu, Yongning

2014-05-01

To establish a method for the determination of fatty acid esters of 3-monochloropropane-1, 2-diol (3-MCPD) and 2-monochloropropane-1, 3-diol (2-MCPD) in diet samples by gas chromatography-mass spectrometry (GC-MS) with solid-supported liquid-liquid extraction (SLE). Diet samples were ultrasonically extracted by hexane, followed by ester cleavage reaction with sodium methylate in methanol, and then purified by solid-supported liquid-liquid extraction. (SLE) using diatomaceous earth as the sorbent. After derivatization with heptafluorobutyrylimidazole, the analytes were detected by GC-MS and quantified by the deuterated internal standards. The limits of detection (LODs) of 3-MCPD esters and 2-MCPD esters in different diet samples were 0.002 - 0.005 mg/kg and 0.002 - 0.006 mg/kg. The average recoveries of 3-MCPD esters and 2-MCPD esters at the spiking levels of 0.05 and 0.1 mg/kg in the diet samples were in the range of 65.9% - 104.2% and 75.4% - 118.0%, respectively, with the relative standard deviations in the range of 2.2% - 14.2% and 0.8% - .13.9%. The method is simple, accurate and rugged for the determination of fatty acid esters of 3-MCPD and 2-MCPD in diet samples.

Numerical study on the flow and heat transfer characteristics of slush nitrogen in a corrugated pipe

NASA Astrophysics Data System (ADS)

Li, Y. J.; Wu, S. Q.; Jin, T.

2017-12-01

Slush nitrogen has lower temperature, higher density and higher heat capacity than that of liquid nitrogen at normal boiling point. It is considered to be a potential coolant for high-temperature superconductive cables (HTS) that would decrease nitrogen consumption and storage cost. The corrugated pipe can help with the enhancement of heat transfer and flexibility of the coolants for HTS cables. In this paper, a 3-D Euler-Euler two-fluid model has been developed to study the flow and heat transfer characteristics of slush nitrogen in a horizontal helically corrugated pipe. By comparing with the empirical formula for pressure drop, the numerical model is confirmed to be effective for the prediction of slush nitrogen flow in corrugated pipes. The flow and heat transfer characteristics of slush nitrogen in a horizontal pipe at various working conditions (inlet solid fraction of 0-20%, inlet velocity of 0-3 m/s, heat flux of 0-12 kW/m2) have been analyzed. The friction factor of slush nitrogen is lower than that of subcooled liquid nitrogen when the slush Reynolds number is higher than 4.2×104. Moreover, the heat transfer coefficient of slush nitrogen flow in the corrugated pipe is higher than that of subcooled liquid nitrogen at velocities which is higher than that 1.76 m/s, 0.91 m/s and 0.55 m/s for slush nitrogen with solid fraction of 5%, 10% and 20%, respectively. The slush nitrogen has been confirmed to have better heat transfer performance and lower pressure drop instead of using liquid nitrogen flowing through a helically corrugated pipe.

Two-dimensional solid-phase extraction strategy for the selective enrichment of aminoglycosides in milk.

PubMed

Shen, Aijin; Wei, Jie; Yan, Jingyu; Jin, Gaowa; Ding, Junjie; Yang, Bingcheng; Guo, Zhimou; Zhang, Feifang; Liang, Xinmiao

2017-03-01

An orthogonal two-dimensional solid-phase extraction strategy was established for the selective enrichment of three aminoglycosides including spectinomycin, streptomycin, and dihydrostreptomycin in milk. A reversed-phase liquid chromatography material (C 18 ) and a weak cation-exchange material (TGA) were integrated in a single solid-phase extraction cartridge. The feasibility of two-dimensional clean-up procedure that experienced two-step adsorption, two-step rinsing, and two-step elution was systematically investigated. Based on the orthogonality of reversed-phase and weak cation-exchange procedures, the two-dimensional solid-phase extraction strategy could minimize the interference from the hydrophobic matrix existing in traditional reversed-phase solid-phase extraction. In addition, high ionic strength in the extracts could be effectively removed before the second dimension of weak cation-exchange solid-phase extraction. Combined with liquid chromatography and tandem mass spectrometry, the optimized procedure was validated according to the European Union Commission directive 2002/657/EC. A good performance was achieved in terms of linearity, recovery, precision, decision limit, and detection capability in milk. Finally, the optimized two-dimensional clean-up procedure incorporated with liquid chromatography and tandem mass spectrometry was successfully applied to the rapid monitoring of aminoglycoside residues in milk. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Self-Pressurization and Spray Cooling Simulations of the Multipurpose Hydrogen Test Bed (MHTB) Ground-Based Experiment

NASA Technical Reports Server (NTRS)

Kartuzova, O.; Kassemi, M.; Agui, J.; Moder, J.

2014-01-01

This paper presents a CFD (computational fluid dynamics) model for simulating the self-pressurization of a large scale liquid hydrogen storage tank. In this model, the kinetics-based Schrage equation is used to account for the evaporative and condensing interfacial mass flows. Laminar and turbulent approaches to modeling natural convection in the tank and heat and mass transfer at the interface are compared. The flow, temperature, and interfacial mass fluxes predicted by these two approaches during tank self-pressurization are compared against each other. The ullage pressure and vapor temperature evolutions are also compared against experimental data obtained from the MHTB (Multipuprpose Hydrogen Test Bed) self-pressurization experiment. A CFD model for cooling cryogenic storage tanks by spraying cold liquid in the ullage is also presented. The Euler- Lagrange approach is utilized for tracking the spray droplets and for modeling interaction between the droplets and the continuous phase (ullage). The spray model is coupled with the VOF (volume of fluid) model by performing particle tracking in the ullage, removing particles from the ullage when they reach the interface, and then adding their contributions to the liquid. Droplet ullage heat and mass transfer are modeled. The flow, temperature, and interfacial mass flux predicted by the model are presented. The ullage pressure is compared with experimental data obtained from the MHTB spray bar mixing experiment. The results of the models with only droplet/ullage heat transfer and with heat and mass transfer between the droplets and ullage are compared.

Non-equilibrium dynamics of 2D liquid crystals driven by transmembrane gas flow.

PubMed

Seki, Kazuyoshi; Ueda, Ken; Okumura, Yu-ichi; Tabe, Yuka

2011-07-20

Free-standing films composed of several layers of chiral smectic liquid crystals (SmC*) exhibited unidirectional director precession under various vapor transfers across the films. When the transferred vapors were general organic solvents, the precession speed linearly depended on the momentum of the transmembrane vapors, where the proportional constant was independent of the kind of vapor. In contrast, the same SmC* films under water transfer exhibited precession in the opposite direction. As a possible reason for the rotational inversion, we suggest the competition of two origins for the torques, one of which is microscopic and the other macroscopic. Next, we tried to move an external object by making use of the liquid crystal (LC) motion. When a solid or a liquid particle was set on a film under vapor transfer, the particle was rotated in the same direction as the LC molecules. Using home-made laser tweezers, we measured the force transmitted from the film to the particle, which we found to be several pN.

How pinning and contact angle hysteresis govern quasi-static liquid drop transfer.

PubMed

Chen, H; Tang, T; Zhao, H; Law, K-Y; Amirfazli, A

2016-02-21

This paper presents both experimental and numerical simulations of liquid transfer between two solid surfaces with contact angle hysteresis (CAH). Systematic studies on the role of the advancing contact angle (θa), receding contact angle (θr) and CAH in determining the transfer ratio (volume of the liquid transferred onto the acceptor surface over the total liquid volume) and the maximum adhesion force (Fmax) were performed. The transfer ratio was found to be governed by contact line pinning at the end of the transfer process caused by CAH of surfaces. A map based on θr of the two surfaces was generated to identify the three regimes for liquid transfer: (I) contact line pinning occurs only on the donor surface, (II) contact line pinning occurs on both surfaces, and (III) contact line pinning occurs only on the acceptor surface. With this map, an empirical equation is provided which is able to estimate the transfer ratio by only knowing θr of the two surfaces. The value of Fmax is found to be strongly influenced by the contact line pinning in the early stretching stage. For symmetric liquid bridges between two identical surfaces, Fmax may be determined only by θa, only by θr, or by both θa and θr, depending on the magnitude of the contact angles. For asymmetric bridges, Fmax is found to be affected by the period when contact lines are pinned on both surfaces.

Salt loaded heat pipes: steady-state operation and related heat and mass transport

NASA Astrophysics Data System (ADS)

Simakin, A.; Ghassemi, A.

2003-10-01

Fluids in the deep-seated zones (3.5-4.5 km) of active geothermal zones are known to have increased salinity and acidity that can enhance interaction with surrounding porous rocks. A possible mechanism for brine generation is the separation of the rising magmatic fluid into a gas-like and a liquid-like component. This work illustrates the main features of this mechanism by investigating the conditions for heat pipe convection of natural brines in hydrothermal systems. The well-established heat pipe regime for convection of two-phase pure water (vapor-liquid) in a porous column is extended to the case of boiling brines. In particular, the NaCl-H 2O system is used to model the 1-D reactive flow with dissolution-precipitation in geothermal reservoirs. The quasi steady-state equations of the conservation of matter, Darcy's law for the gas and liquid phases, and the heat balance equation have been examined while neglecting the temporal variation of porosity. A semi-analytical procedure is used to solve these equations for a two-phase fluid in equilibrium with a solid salt. The solution is in the form of the dependence of liquid volume fraction as a function of temperature for different heat fluxes. The solution is separated into two isolated regions by the temperature T=596°C, at the maximum fluid pressure for three-phase (H-L-V) equilibrium. In the case of unsaturated two-phase flow at the reference permeability of porous rocks (3·10 -16 m 2), the maximum heat flux that can be transferred through the porous column via convection is analytically estimated to be 4.3 W/m 2. This is close to the corresponding value for the three-phase case that is numerically calculated to be 6 W/m 2. Due to dissolution (partial leaching of oxide components by acid condensates) and precipitation of salt at the boiling front, heat transfer in a heat pipe in soluble media occurs in a direction opposite to the associated mass transfer. This can cause deep hydrothermal karsting that is manifested as surface subsidence at rates of about several cm/yr as observed in some active geothermal fields.

Compensating effect of ultrasonic waves on retarding action of nanoparticles in drops liquid-liquid extraction.

PubMed

Saien, Javad; Daneshamoz, Sana

2018-03-01

The influence of ultrasonic waves on liquid-liquid extraction of circulating drops and in the presence of magnetite nanoparticles was investigated. Experiments were conducted in a column equipped with an ultrasound transducer. The frequency and intensity of received waves, measured by the hydrophone standard method, were 35.40 kHz and 0.37 mW/cm 2 , respectively. The recommended chemical system of cumene-isobutyric acid-water was used in which mass transfer resistance lies in the aqueous phase. Nanoparticles, within concentration range of (0.0003-0.0030) wt%, were added to the aqueous continuous phase. The presence of nanoparticles and ultrasonic waves provided no sensible change in drop size (within 2.49-4.17 mm) and measured terminal velocities were close to Grace model. However, presence of nanoparticles, caused mass transfer to decrease. This undesired effect was significantly diminished by using ultrasonic waves so that mass transfer coefficient increased from (73.0-178.2) to (130.2-240.2) µm/s, providing a 55.6% average enhancement. It is presumably due to disturbing the accumulated nanoparticles around the drops. The current innovative study highlights the fact that using ultrasonic waves is an interesting way to improve liquid-liquid extraction in the presence and absence of nanoparticles. Copyright © 2017 Elsevier B.V. All rights reserved.

Thermal Enhancement of Silicon Carbide (SiC) Power Electronics and Laser Bars: Statistical Design Optimization of a Liquid-Cooled Power Electronic Heat Sink

DTIC Science & Technology

2015-08-01

Forced Convective Heat Transfer Across a Pin Fin Micro Heat Sink”, International Journal of Heat and Mass Transfer 48 (2005) 3615-3627. 3. Cao...from Pin Fins Situated in an Oncoming Longitudinal Flow Which Turns to Crossflow”, International Journal of Heat and Mass Transfer, Vol. 25 No. 5...Flow Forced Convection”, International Journal of Heat and Mass Transfer, Vol. 39, No. 2, pp. 311-317, 1996. 11. Khan, W., Culham, J., and Yovanovich

Hollow fiber apparatus and use thereof for fluids separations and heat and mass transfers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bikson, Benjamin; Etter, Stephen; Ching, Nathaniel

A hollow fiber device includes a hollow fiber bundle, comprising a plurality of hollow fibers, a first tubesheet and a second tubesheet encapsulating respective distal ends of the hollow fiber bundle. The tubesheets have boreholes in fluid communication with bores of the hollow fibers. In at least one of the tubesheets, the boreholes are formed radially. The hollow fiber device can be utilized in heat exchange, in gas/gas, liquid/liquid and gas/liquid heat transfer, in combined heat and mass transfer and in fluid separation assemblies and processes. The design disclosed herein is light weight and compact and is particularly advantageous whenmore » the pressure of a first fluid introduced into the bores of hollow fibers is higher than the pressure on the shell side of the device.« less

Supercritical fluid precipitation of ketoprofen in novel structured lipid carriers for enhanced mucosal delivery--a comparison with solid lipid particles.

PubMed

Gonçalves, V S S; Matias, A A; Rodríguez-Rojo, S; Nogueira, I D; Duarte, C M M

2015-11-10

Structured lipid carriers based on mixture of solid lipids with liquid lipids are the second generation of solid lipid particles, offering the advantage of improved drug loading capacity and higher storage stability. In this study, structured lipid carriers were successfully prepared for the first time by precipitation from gas saturated solutions. Glyceryl monooleate (GMO), a liquid glycerolipid, was selected in this work to be incorporated into three solid glycerolipids with hydrophilic-lipophilic balance (HLB) ranging from 1 to 13, namely Gelucire 43/01™, Geleol™ and Gelucire 50/13™. In general, microparticles with a irregular porous morphology and a wide particle size distribution were obtained. The HLB of the individual glycerolipids might be a relevant parameter to take into account during the processing of solid:liquid lipid blends. As expected, the addition of a liquid lipid into a solid lipid matrix led to increased stability of the lipid carriers, with no significant modifications in their melting enthalpy after 6 months of storage. Additionally, Gelucire 43/01™:GMO particles were produced with different mass ratios and loaded with ketoprofen. The drug loading capacity of the structured lipid carriers increased as the GMO content in the particles increased, achieving a maximum encapsulation efficiency of 97% for the 3:1 mass ratio. Moreover, structured lipid carriers presented an immediate release of ketoprofen from its matrix with higher permeation through a mucous-membrane model, while solid lipid particles present a controlled release of the drug with less permeation capacity. Copyright © 2015. Published by Elsevier B.V.

Detection of monohydroxylated polycyclic aromatic hydrocarbons in urine and particulate matter using LC separations coupled with integrated SPE and fluorescence detection or coupled with high-resolution time-of-flight mass spectrometry.

PubMed

Lintelmann, Jutta; Wu, Xiao; Kuhn, Evelyn; Ritter, Sebastian; Schmidt, Claudia; Zimmermann, Ralf

2018-05-01

A high-performance liquid chromatographic (HPLC) method with integrated solid-phase extraction for the determination of 1-hydroxypyrene and 1-, 2-, 3-, 4- and 9-hydroxyphenanthrene in urine was developed and validated. After enzymatic treatment and centrifugation of 500 μL urine, 100 μL of the sample was directly injected into the HPLC system. Integrated solid-phase extraction was performed on a selective, copper phthalocyanine modified packing material. Subsequent chromatographic separation was achieved on a pentafluorophenyl core-shell column using a methanol gradient. For quantification, time-programmed fluorescence detection was used. Matrix-dependent recoveries were between 94.8 and 102.4%, repeatability and reproducibility ranged from 2.2 to 17.9% and detection limits lay between 2.6 and 13.6 ng/L urine. A set of 16 samples from normally exposed adults was analyzed using this HPLC-fluorescence detection method. Results were comparable with those reported in other studies. The chromatographic separation of the method was transferred to an ultra-high-performance liquid chromatography pentafluorophenyl core-shell column and coupled to a high-resolution time-of-flight mass spectrometer (HR-TOF-MS). The resulting method was used to demonstrate the applicability of LC-HR-TOF-MS for simultaneous target and suspect screening of monohydroxylated polycyclic aromatic hydrocarbons in extracts of urine and particulate matter. Copyright © 2018 John Wiley & Sons, Ltd.

Advanced analytical techniques for the extraction and characterization of plant-derived essential oils by gas chromatography with mass spectrometry.

PubMed

Waseem, Rabia; Low, Kah Hin

2015-02-01

In recent years, essential oils have received a growing interest because of the positive health effects of their novel characteristics such as antibacterial, antifungal, and antioxidant activities. For the extraction of plant-derived essential oils, there is the need of advanced analytical techniques and innovative methodologies. An exhaustive study of hydrodistillation, supercritical fluid extraction, ultrasound- and microwave-assisted extraction, solid-phase microextraction, pressurized liquid extraction, pressurized hot water extraction, liquid-liquid extraction, liquid-phase microextraction, matrix solid-phase dispersion, and gas chromatography (one- and two-dimensional) hyphenated with mass spectrometry for the extraction through various plant species and analysis of essential oils has been provided in this review. Essential oils are composed of mainly terpenes and terpenoids with low-molecular-weight aromatic and aliphatic constituents that are particularly important for public health. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

An Experiment to Introduce Mass Transfer Concepts Using a Commercial Hollow Fiber Blood Oxygenator

ERIC Educational Resources Information Center

McIver, Keith; Merrill, Thomas; Farrell, Stephanie

2017-01-01

A commercial hollow fiber blood oxygenation laboratory experiment was used to introduce lower level engineering students to mass balances in a two-phase system. Using measured values of concentration and flow rate, students calculated the rate of mass transfer from the gas phase and into the liquid phase, and compared the two values to determine…

Transient Effects in Turbulence Modelling.

DTIC Science & Technology

1979-12-01

plenum region of a liquid-metal- cooled fast breeder reactor (LMFBR). The efficient heat transfer characteristics of liquid metal coolant, combined...Transients in Generalized Liquid-Metal Fast Breeder Reactor Outlet Plenums," Nuclear Technology, Vol. 44, July 1979, p. 210. 135 15. Lorenz, J. J., "MIX... Sodium Coolant in the Outlet Plenum of a Fast Nuclear Reactor ," Int. J. Heat Mass Transfer, Vol. 21, 1978, pp. 1565-1579. 19. Chen, Y. B., Golay, M. W

Heat and mass transfer correlations for liquid droplet of a pure fuel in combustion

NASA Astrophysics Data System (ADS)

Dgheim, J.; Chesneau, X.; Pietri, L.; Zeghmati, B.

The authors report a numerical analysis of heat and mass transfers, which govern the combustion of a fuel droplet assimilated to a sphere. The results are presented in the form of temperature, mass-fraction, Nusselt and Sherwood number profiles. The following heat and mass transfers correlations are developed: ; , which account for the effects of natural convection and the physical properties of the gas phase. These correlations agree with the results of detailed numerical analysis as well as the experimental data involving a single droplet.

Acrylamide: formation, occurrence in food products, detection methods, and legislation.

PubMed

Arvanitoyannis, Ioannis S; Dionisopoulou, Niki

2014-01-01

This review aims at summarizing the most recent updates in the field of acrylamide (AA) formation (mechanism, conditions) and the determination of AA in a number of foods (fried or baked potatoes, chips, coffee, bread, etc). The methods applied for AA detection [Capillary Electrophoresis-Mass Spectrometry (CE-MS), Liquid Chromatography-Mass Spectrometry (LC-MS), Non-Aqueous Capillary Electrophoresis (NACE), High Performance Liquid Chromatography-Mass Spectrometry (HPLC-MS), Pressurized Fluid Extraction (PFE), Matrix Solid-Phase Dispersion (MSPD), Gas Chromatography-Mass Spectrometry (GC-MS), Solid-Phase MicroExtraction-Gas Chromatography (SPME-GC), Enzyme Linked Immunosorbent Assay (ELISA), and MicroEmulsion ElectroKinetic Chromatography (MEEKC) are presented and commented. Several informative figures and tables are included to show the effect of conditions (temperature, time) on the AA formation. A section is also included related to AA legislation in EU and US.

Ignition transient analysis of solid rocket motor

NASA Technical Reports Server (NTRS)

Han, Samuel S.

1990-01-01

To predict pressure-time and thrust-time behavior of solid rocket motors, a one-dimensional numerical model is developed. The ignition phase of solid rocket motors (time less than 0.4 sec) depends critically on complex interactions among many elements, such as rocket geometry, heat and mass transfer, flow development, and chemical reactions. The present model solves the mass, momentum, and energy equations governing the transfer processes in the rocket chamber as well as the attached converging-diverging nozzle. A qualitative agreement with the SRM test data in terms of head-end pressure gradient and the total thrust build-up is obtained. Numerical results show that the burning rate in the star-segmented head-end section and the erosive burning are two important parameters in the ignition transient of the solid rocket motor (SRM).

Liquid and Solid Meal Replacement Products Differentially Affect Postprandial Appetite and Food Intake in Older Adults

PubMed Central

Stull, April J.; Apolzan, John W.; Thalacker-Mercer, Anna E.; Iglay, Heidi B.; Campbell, Wayne W.

2008-01-01

Liquid and solid foods are documented to elicit differential appetitive and food intake responses. This study was designed to assess the influences of liquid vs solid meal replacement products on postprandial appetite ratings and subsequent food intake in healthy older adults. This study used a randomized and crossover design with two 1-day trials (1 week between trials), and 24 adults (12 men and 12 women) aged 50 to 80 years with body mass index (calculated as kg/m2) between 22 and 30 participated. After an overnight fast, the subjects consumed meal replacement products as either a beverage (liquid) or a bar (solid). The meal replacement products provided 25% of each subject's daily estimated energy needs with comparable macro-nutrient compositions. Subjects rated their appetite on a 100 mm quasilogarithmic visual analog scale before and 15, 30, 45, 60, 90, 120, and 150 minutes after consuming the meal replacement product. At minute 120, each subject consumed cooked oatmeal ad libitum to a “comfortable level of fullness.” Postprandial composite (area under the curve from minute 15 to minute 120) hunger was higher (P=0.04) for the liquid vs solid meal replacement products and desire to eat (P=0.15), preoccupation with thoughts of food (P=0.07), and fullness (P=0.25) did not differ for the liquid vs solid meal replacement products. On average, the subjects consumed 13.4% more oatmeal after the liquid vs solid (P=0.006) meal replacement product. These results indicate that meal replacement products in liquid and solid form do not elicit comparable appetitive and ingestive behavior responses and that meal replacement products in liquid form blunt the postprandial decline in hunger and increase subsequent food intake in older adults. PMID:18589034

Handheld low-temperature plasma probe for portable "point-and-shoot" ambient ionization mass spectrometry.

PubMed

Wiley, Joshua S; Shelley, Jacob T; Cooks, R Graham

2013-07-16

We describe a handheld, wireless low-temperature plasma (LTP) ambient ionization source and its performance on a benchtop and a miniature mass spectrometer. The source, which is inexpensive to build and operate, is battery-powered and utilizes miniature helium cylinders or air as the discharge gas. Comparison of a conventional, large-scale LTP source against the handheld LTP source, which uses less helium and power than the large-scale version, revealed that the handheld source had similar or slightly better analytical performance. Another advantage of the handheld LTP source is the ability to quickly interrogate a gaseous, liquid, or solid sample without requiring any setup time. A small, 7.4-V Li-polymer battery is able to sustain plasma for 2 h continuously, while the miniature helium cylinder supplies gas flow for approximately 8 continuous hours. Long-distance ion transfer was achieved for distances up to 1 m.

Polarization and mass transfer during the electrolysis of molten salts with liquid metallic electrodes

NASA Astrophysics Data System (ADS)

Mikhalev, Yu. G.

2014-08-01

Calculations are used to show that the fraction of the overvoltage of the stage of discharge-ionization can be significant in the total overvoltage during the polarization of liquid metallic electrodes in molten chlorides depleted of electrochemically active particles (depending on the type of the dissipative structures that appear near the electrode/electrolyte interface). This finding is taken into account to obtain criterion equations to describe the mass-transfer rate as a function of the physicochemical properties of the electrolyte and the metal electrode.

Solid Loss of Carrots During Simulated Gastric Digestion.

PubMed

Kong, Fanbin; Singh, R Paul

2011-03-01

The knowledge of solid loss kinetics of foods during digestion is crucial for understanding the factors that constrain the release of nutrients from the food matrix and their fate of digestion. The objective of this study was to investigate the solid loss of carrots during simulated gastric digestion as affected by pH, temperature, viscosity of gastric fluids, mechanical force present in stomach, and cooking. Cylindrical carrot samples were tested by static soaking method and using a model stomach system. The weight retention, moisture, and loss of dry mass were determined. The results indicated that acid hydrolysis is critical for an efficient mass transfer and carrot digestion. Internal resistance rather than external resistance is dominant in the transfer of soluble solids from carrot to gastric fluid. Increase in viscosity of gastric fluid by adding 0.5% gum (w/w) significantly increased the external resistance and decreased mass transfer rate of carrots in static soaking. When mechanical force was not present, 61% of the solids in the raw carrot samples were released into gastric fluid after 4 h of static soaking in simulated gastric juice. Mechanical force significantly increased solid loss by causing surface erosion. Boiling increased the disintegration of carrot during digestion that may favor the loss of solids meanwhile reducing the amount of solids available for loss in gastric juice. Weibull function was successfully used to describe the solid loss of carrot during simulated digestion. The effective diffusion coefficients of solids were calculated using the Fick's second law of diffusion for an infinite cylinder, which are between 0.75 × 10(-11) and 8.72 × 10(-11) m(2)/s, depending on the pH of the gastric fluid.

Burnout and distribution of liquid between the flow core and wall films in narrow slot channels

NASA Astrophysics Data System (ADS)

Boltenko, E. A.; Shpakovskii, A. A.

2010-03-01

Previous works on studying distribution of liquid between the flow core and wall films in narrow slot channels are briefly reviewed. Interrelation between mass transfer processes and burnout is shown. A procedure for calculating burnout on convex and concave heat-transfer surfaces in narrow slot channels is presented.

Modeling of ultrasound transmission through a solid-liquid interface comprising a network of gas pockets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Paumel, K.; Baque, F.; Moysan, J.

Ultrasonic inspection of sodium-cooled fast reactor requires a good acoustic coupling between the transducer and the liquid sodium. Ultrasonic transmission through a solid surface in contact with liquid sodium can be complex due to the presence of microscopic gas pockets entrapped by the surface roughness. Experiments are run using substrates with controlled roughness consisting of a network of holes and a modeling approach is then developed. In this model, a gas pocket stiffness at a partially solid-liquid interface is defined. This stiffness is then used to calculate the transmission coefficient of ultrasound at the entire interface. The gas pocket stiffnessmore » has a static, as well as an inertial component, which depends on the ultrasonic frequency and the radiative mass.« less

Overcoming the Gas-Liquid Mass Transfer of Oxygen by Coupling Photosynthetic Water Oxidation with Biocatalytic Oxyfunctionalization.

PubMed

Hoschek, Anna; Bühler, Bruno; Schmid, Andreas

2017-11-20

Gas-liquid mass transfer of gaseous reactants is a major limitation for high space-time yields, especially for O 2 -dependent (bio)catalytic reactions in aqueous solutions. Herein, oxygenic photosynthesis was used for homogeneous O 2 supply via in situ generation in the liquid phase to overcome this limitation. The phototrophic cyanobacterium Synechocystis sp. PCC6803 was engineered to synthesize the alkane monooxygenase AlkBGT from Pseudomonas putida GPo1. With light, but without external addition of O 2 , the chemo- and regioselective hydroxylation of nonanoic acid methyl ester to ω-hydroxynonanoic acid methyl ester was driven by O 2 generated through photosynthetic water oxidation. Photosynthesis also delivered the necessary reduction equivalents to regenerate the Fe 2+ center in AlkB for oxygen transfer to the terminal methyl group. The in situ coupling of oxygenic photosynthesis to O 2 -transferring enzymes now enables the design of fast hydrocarbon oxyfunctionalization reactions. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of particle-particle shearing on the bioleaching of sulfide minerals.

PubMed

Chong, N; Karamanev, D G; Margaritis, A

2002-11-05

The biological leaching of sulfide minerals, used for the production of gold, copper, zinc, cobalt, and other metals, is very often carried out in slurry bioreactors, where the shearing between sulfide particles is intensive. In order to be able to improve the efficiency of the bioleaching, it is of significant importance to know the effect of particle shearing on the rate of leaching. The recently proposed concept of ore immobilization allowed us to study the effect of particle shearing on the rate of sulfide (pyrite) leaching by Thiobacillus ferrooxidans. Using this concept, we designed two very similar bioreactors, the main difference between which was the presence and absence of particle-particle shearing. It was shown that when the oxygen mass transfer was not the rate-limiting step, the rate of bioleaching in the frictionless bioreactor was 2.5 times higher than that in a bioreactor with particle friction (shearing). The concentration of free suspended cells in the frictionless bioreactor was by orders of magnitude lower than that in the frictional bioreactor, which showed that particle friction strongly reduces the microbial attachment to sulfide surface, which, in turn, reduces the rate of bioleaching. Surprisingly, it was found that formation of a layer of insoluble iron salts on the surface of sulfide particles is much slower under shearless conditions than in the presence of particle-particle shearing. This was explained by the effect of particle friction on liquid-solid mass transfer rate. The results of this study show that reduction of the particle friction during bioleaching of sulfide minerals can bring important advantages not only by increasing significantly the bioleaching rate, but also by increasing the rate of gas-liquid oxygen mass transfer, reducing the formation of iron precipitates and reducing the energy consumption. One of the efficient methods for reduction of particle friction is ore immobilization in a porous matrix. Copyright 2002 Wiley Periodicals, Inc. Biotechnol Bioeng 80: 349-357, 2002.

A Review of Microbubble and its Applications in Ozonation

NASA Astrophysics Data System (ADS)

Shangguan, Yufei; Yu, Shuili; Gong, Chao; Wang, Yue; Yang, Wangzhen; Hou, Li-an

2018-03-01

Ozonation has been demonstrated to be an effective technology for the oxidation of organic matters in water treatment. But the low solubility and low mass transfer efficiency limit the application. Microbubble technology has the potential of enhancing gas-liquid mass transfer efficiency, thus it can be applied in ozonation process. The applications of microbubble ozonation have shown advantages over macro bubble ozonation in mass transfer and reaction rate. Microbubble ozonation will be a promising treatment both in water and wastewater treatment.

Microvolume trace environmental analysis using peak-focusing online solid-phase extraction-nano-liquid chromatography-high-resolution mass spectrometry.

PubMed

Stravs, Michael A; Mechelke, Jonas; Ferguson, P Lee; Singer, Heinz; Hollender, Juliane

2016-03-01

Online solid-phase extraction was combined with nano-liquid chromatography coupled to high-resolution mass spectrometry (HRMS) for the analysis of micropollutants in environmental samples from small volumes. The method was validated in surface water, Microcystis aeruginosa cell lysate, and spent Microcystis growth medium. For 41 analytes, quantification limits of 0.1-28 ng/L (surface water) and 0.1-32 ng/L (growth medium) were obtained from only 88 μL of sample. In cell lysate, quantification limits ranged from 0.1-143 ng/L or 0.33-476 ng/g dry weight from a sample of 88 μL, or 26 μg dry weight, respectively. The method matches the sensitivity of established online and offline solid-phase extraction-liquid chromatography-mass spectrometry methods but requires only a fraction of the sample used by those techniques, and is among the first applications of nano-LC-MS for environmental analysis. The method was applied to the determination of bioconcentration in Microcystis aeruginosa in a laboratory experiment, and the benefit of coupling to HRMS was demonstrated in a transformation product screening.

Experimental and numerical investigation of Acoustic streaming (Eckart streaming)

NASA Astrophysics Data System (ADS)

Dridi, Walid; Botton, Valery; Henry, Daniel; Ben Hadid, Hamda

The application of sound waves in the bulk of a fluid can generate steady or quasi-steady flows reffered to as Acoustic streaming flows. We can distinguish two kind of acoustic streaming: The Rayleigh Streaming is generated when a standing acoustic waves interfere with solid walls to give birth to an acoustic boundary layer. Steady recirculations are then driven out of the boundary layer and can be used in micro-gravity, where the free convection is too weak or absent, to enhance the convective heat or mass transfer and cooling the electronic devises [1]. The second kind is the Eckart streaming, which is a flow generated far from the solid boundaries, it can be used to mix a chemical solutions [2], and to drive a viscous liquids in channels [3-4], in micro-gravity area. Our study focuses on the Eckart streaming configuration, which is investigated both numerical and experimental means. The experimental configuration is restricted to the case of a cylindrical non-heated cavity full of water or of a water+glycerol mixture. At the middle of one side of the cavity, a plane ultrasonic transducer generates a 2MHz wave; an absorber is set at the opposite side of the cavity to avoid any reflections. The velocity field is measured with a standard PIV system. [1] P. Vainshtein, M. Fichman and C. Gutfinger, "Acoustic enhancement of heat transfer between two parallel plates", International Journal of Heat and Mass Transfert, 1995, 38(10), 1893. [2] C. Suri, K. Tekenaka, H. Yanagida, Y. Kojima and K. Koyama, "Chaotic mixing generated by acoustic streaming", Ultrasonics, 2002, 40, 393 [3] O.V. Rudenko and A.A. Sukhorukov, "Nonstationnary Eckart streaming and pumping of liquid in ultrasonic field", Acoustical Physics, 1998, 44, 653. [4] Kenneth D. Frampton, Shawn E. Martin and Keith Minor, "The scaling of acoustic streaming for application in micro-fluidic devices", Applied Acoustics, 2003, 64,681

Small-scale experimental study of vaporization flux of liquid nitrogen released on water.

PubMed

Gopalaswami, Nirupama; Olewski, Tomasz; Véchot, Luc N; Mannan, M Sam

2015-10-30

A small-scale experimental study was conducted using liquid nitrogen to investigate the convective heat transfer behavior of cryogenic liquids released on water. The experiment was performed by spilling five different amounts of liquid nitrogen at different release rates and initial water temperatures. The vaporization mass fluxes of liquid nitrogen were determined directly from the mass loss measured during the experiment. A variation of initial vaporization fluxes and a subsequent shift in heat transfer mechanism were observed with changes in initial water temperature. The initial vaporization fluxes were directly dependent on the liquid nitrogen spill rate. The heat flux from water to liquid nitrogen determined from experimental data was validated with two theoretical correlations for convective boiling. It was also observed from validation with correlations that liquid nitrogen was found to be predominantly in the film boiling regime. The substantial results provide a suitable procedure for predicting the heat flux from water to cryogenic liquids that is required for source term modeling. Copyright © 2015 Elsevier B.V. All rights reserved.

Kinetic model of mass transfer through gas liquid interface in laser surface alloying

NASA Astrophysics Data System (ADS)

Gnedovets, A. G.; Portnov, O. M.; Smurov, I.; Flamant, G.

1997-02-01

In laser surface alloying from gas atmosphere neither surface concentration nor the flux of the alloying elements are known beforehand. They should be determined from the combined solution of heat and mass transfer equations with an account for the kinetics of interaction of a gas with a melt. Kinetic theory description of mass transfer through the gas-liquid interface is applied to the problem of laser surface alloying of iron from the atmosphere of molecular nitrogen. The activation nature of gas molecules dissociation at the surface is considered. It is shown that under pulsed-periodic laser action the concentration profiles of the alloying element have maxima situated close to the surface of the metal. The efficiency of surface alloying increases steeply under laser-plasma conditions which results in the formation of highly supersaturated gas solutions in the metal.

Electrokinetic removal of radionuclides contained in scintillation liquids absorbed in soil type Phaeozem.

PubMed

Valdovinos, V; Monroy-Guzmán, F; Bustos, E

2016-10-01

Control samples of scintillation liquids - Phaeozem soil mixtures were prepared with different scintillation liquids as the support electrolyte, Install Gel ® XF, (Ultima Gold AB™ and Ultima Gold XR™), to construct the polarization curves, and to select the cell potential with the highest mass transfer to remove 24 Na (15 h) and 99m Tc (6 h) as radiotracers from polluted Phaeozem soil. During the electrokinetic treatment (EKT), the removal of radionuclides contained in scintillation liquids absorbed in Phaeozem soil, liquid phase was characterized by Gas Chromatography coupled with a Flame Ionization Detector (GC-FID) and Fourier Transform Infrared Spectrometry (FTIR), solids by FTIR, before and after the application of cell potential. In this sense, the support electrolyte was selected based on the highest current generated (1 mA), as in the case of scintillation liquid 50% Ultima Gold XR™ + 50% Water (1:1), which was used for 6 h in the presence of a mesh and a titanium rod, as anode and cathode, respectively. Finally, the removal percentage accumulated in the liquid phase after the EKT of Phaeozem soil polluted by 99m Tc was 61% close to the anode after 4 h. It was also 61% for 24 Na close to cathode after 2 h, and after 4 h it was 71.8%. Copyright © 2016 Elsevier Ltd. All rights reserved.

Thermal-Flow Code for Modeling Gas Dynamics and Heat Transfer in Space Shuttle Solid Rocket Motor Joints

NASA Technical Reports Server (NTRS)

Wang, Qunzhen; Mathias, Edward C.; Heman, Joe R.; Smith, Cory W.

2000-01-01

A new, thermal-flow simulation code, called SFLOW. has been developed to model the gas dynamics, heat transfer, as well as O-ring and flow path erosion inside the space shuttle solid rocket motor joints by combining SINDA/Glo, a commercial thermal analyzer. and SHARPO, a general-purpose CFD code developed at Thiokol Propulsion. SHARP was modified so that friction, heat transfer, mass addition, as well as minor losses in one-dimensional flow can be taken into account. The pressure, temperature and velocity of the combustion gas in the leak paths are calculated in SHARP by solving the time-dependent Navier-Stokes equations while the heat conduction in the solid is modeled by SINDA/G. The two codes are coupled by the heat flux at the solid-gas interface. A few test cases are presented and the results from SFLOW agree very well with the exact solutions or experimental data. These cases include Fanno flow where friction is important, Rayleigh flow where heat transfer between gas and solid is important, flow with mass addition due to the erosion of the solid wall, a transient volume venting process, as well as some transient one-dimensional flows with analytical solutions. In addition, SFLOW is applied to model the RSRM nozzle joint 4 subscale hot-flow tests and the predicted pressures, temperatures (both gas and solid), and O-ring erosions agree well with the experimental data. It was also found that the heat transfer between gas and solid has a major effect on the pressures and temperatures of the fill bottles in the RSRM nozzle joint 4 configuration No. 8 test.

Gold catalyzed nickel disilicide formation: a new solid-liquid-solid phase growth mechanism.

PubMed

Tang, Wei; Picraux, S Tom; Huang, Jian Yu; Liu, Xiaohua; Tu, K N; Dayeh, Shadi A

2013-01-01

The vapor-liquid-solid (VLS) mechanism is the predominate growth mechanism for semiconductor nanowires (NWs). We report here a new solid-liquid-solid (SLS) growth mechanism of a silicide phase in Si NWs using in situ transmission electron microcopy (TEM). The new SLS mechanism is analogous to the VLS one in relying on a liquid-mediating growth seed, but it is fundamentally different in terms of nucleation and mass transport. In SLS growth of Ni disilicide, the Ni atoms are supplied from remote Ni particles by interstitial diffusion through a Si NW to the pre-existing Au-Si liquid alloy drop at the tip of the NW. Upon supersaturation of both Ni and Si in Au, an octahedral nucleus of Ni disilicide (NiSi2) forms at the center of the Au liquid alloy, which thereafter sweeps through the Si NW and transforms Si into NiSi2. The dissolution of Si by the Au alloy liquid mediating layer proceeds with contact angle oscillation at the triple point where Si, oxide of Si, and the Au alloy meet, whereas NiSi2 is grown from the liquid mediating layer in an atomic stepwise manner. By using in situ quenching experiments, we are able to measure the solubility of Ni and Si in the Au-Ni-Si ternary alloy. The Au-catalyzed mechanism can lower the formation temperature of NiSi2 by 100 °C compared with an all solid state reaction.

Semi-automated 96-well solid-phase extraction and gas chromatography-negative chemical ionization tandem mass spectrometry for the trace analysis of fluprostenol in rat plasma.

PubMed

Gauw, R D; Stoffolano, P J; Kuhlenbeck, D L; Patel, V S; Garver, S M; Baker, T R; Wehmeyer, K R

2000-07-21

Semi-automated 96-well plate solid-phase extraction (SPE) was used for sample preparation of fluprostenol, a prostaglandin analog, in rat plasma prior to detection by gas chromatography-negative chemical ionization tandem mass spectrometry (GC-NCI-MS-MS). A liquid handling system was utilized for all aspects of sample handling prior to SPE including transferring of samples into a 96-well format, preparation of standards as well as addition of internal standard to standards, quality control samples and study samples. SPE was performed in a 96-well plate format using octadecylsilane packing and the effluent from the SPE was dried in a custom-made 96-well apparatus. The sample residue was derivatized sequentially with pentafluorobenzylbromide followed by N-methyl-N-trimethylsilyltrifluoroacetamide. The derivatized sample was then analyzed using GC-NCI-MS-MS. The dynamic range for the method was from 7 to 5800 pg/ml with a 0.1-ml plasma sample. The methodology was evaluated over a 4-day period and demonstrated an accuracy of 90-106% with a precision of 2.4-12.9%.

Mass dependence of spectral and angular distributions of Cherenkov radiation from relativistic isotopes in solid radiators and its possible application as mass selector

NASA Astrophysics Data System (ADS)

Bogdanov, O. V.; Rozhkova, E. I.; Pivovarov, Yu. L.; Kuzminchuk-Feuerstein, N.

2018-02-01

The first proof of principle experiment with a prototype of a Time-of-Flight (TOF) - Cherenkov detector of relativistic heavy ions (RHI) exploiting a liquid Iodine Naphthalene radiator has been performed at Cave C at GSI (Darmstadt, Germany). A conceptual design for a liquid Cherenkov detector was proposed as a prototype for the future TOF measurements at the Super-FRS by detection of total number of Cherenkov photons. The ionization energy loss of RHI in a liquid radiator decreases only slightly this number, while in a solid radiator changes sufficiently not the total number of ChR photons, but ChR angular and spectral distributions. By means of computer simulations, we showed that these distributions are very sensitive to the isotope mass, due to different stopping powers of isotopes with initial equal relativistic factors. The results of simulations for light (Li, Be) and heavy (Xe) isotopes at 500-1000 MeV/u are presented indicating the possibility to use the isotopic effect in ChR of RHI as the mass selector.

Determination of external and internal mass transfer limitation in nitrifying microbial aggregates.

PubMed

Wilén, Britt-Marie; Gapes, Daniel; Keller, Jürg

2004-05-20

In this article we present a study of the effects of external and internal mass transfer limitation of oxygen in a nitrifying system. The oxygen uptake rates (OUR) were measured on both a macro-scale with a respirometric reactor using off-gas analysis (Titrimetric and Off-Gas Analysis (TOGA) sensor) and on a micro-scale with microsensors. These two methods provide independent, accurate measurements of the reaction rates and concentration profiles around and in the granules. The TOGA sensor and microsensor measurements showed a significant external mass transfer effect at low dissolved oxygen (DO) concentrations in the bulk liquid while it was insignificant at higher DO concentrations. The oxygen distribution with anaerobic or anoxic conditions in the center clearly shows major mass transfer limitation in the aggregate interior. The large drop in DO concentration of 22-80% between the bulk liquid and aggregate surface demonstrates that the external mass transfer resistance is also highly important. The maximum OUR even for floccular biomass was only attained at much higher DO concentrations (approximately 8 mg/L) than typically used in such systems. For granules, the DO required for maximal activity was estimated to be >20 mg/L, clearly indicating the effects of the major external and internal mass transfer limitations on the overall biomass activity. Smaller aggregates had a larger volumetric OUR indicating that the granules may have a lower activity in the interior part of the aggregate. Copyright 2004 Wiley Periodicals, Inc.

The influence of polymeric membrane gas spargers on hydrodynamics and mass transfer in bubble column bioreactors.

PubMed

Tirunehe, Gossaye; Norddahl, B

2016-04-01

Gas sparging performances of a flat sheet and tubular polymeric membranes were investigated in 3.1 m bubble column bioreactor operated in a semi batch mode. Air-water and air-CMC (Carboxymethyl cellulose) solutions of 0.5, 0.75 and 1.0 % w/w were used as interacting gas-liquid mediums. CMC solutions were employed in the study to simulate rheological properties of bioreactor broth. Gas holdup, bubble size distribution, interfacial area and gas-liquid mass transfer were studied in the homogeneous bubbly flow hydrodynamic regime with superficial gas velocity (U(G)) range of 0.0004-0.0025 m/s. The study indicated that the tubular membrane sparger produced the highest gas holdup and densely populated fine bubbles with narrow size distribution. An increase in liquid viscosity promoted a shift in bubble size distribution to large stable bubbles and smaller specific interfacial area. The tubular membrane sparger achieved greater interfacial area and an enhanced overall mass transfer coefficient (K(L)a) by a factor of 1.2-1.9 compared to the flat sheet membrane.

Simultaneous determination of 13 phytohormones in oilseed rape tissues by liquid chromatography-electrospray tandem mass spectrometry and the evaluation of the matrix effect.

PubMed

Fan, Sufang; Wang, Xiupin; Li, Peiwu; Zhang, Qi; Zhang, Wen

2011-03-01

In the experiment, a high-performance liquid chromatography and electrospray ionization-tandem mass spectrometry with selected reaction monitoring was used to simultaneously determine various classes of phytohormones, including indole-3-acetic acid, α-naphthaleneacetic acid, 2-chlorobenzoic acid, 4-chlorobenzoic acid, indole-3-butyric acid, gibberellic acid, 2,4-dichlorophenoxyacetic acid, 2-naphthoxyacetic acid, abscisic acid, 2,3,5-triiodobenzoic acid, uniconazole, paclobutrazol and 2,4-epibassinolide in rape tissues. The analyses were separated by an HPLC equipped with a reversed-phase column using a binary solvent system composed of methanol and water, both containing 0.1% of formic acid. The matrix effect was also considered and determined. The technology was applied to analyze rape tissues, including roots, stems, leaves, flowers, immature pods and rape seeds. The rape tissues were subjected to ultrasound-assisted extraction and purified by dispersive solid-phase extraction, and then transferred into the liquid chromatography system. The detection limit for each plant hormone was defined by the ratio of signal/background noise (S/N) of 3. The results showed perfect linearity (R(2) values of 0.9987-1.0000) and reproducibility of elution times (relative standard deviations, RSDs,<1%) and peak areas (RSDs,<7%) for all target compounds. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Redox Electrocatalysis of Floating Nanoparticles: Determining Electrocatalytic Properties without the Influence of Solid Supports.

PubMed

Peljo, Pekka; Scanlon, Micheál D; Olaya, Astrid J; Rivier, Lucie; Smirnov, Evgeny; Girault, Hubert H

2017-08-03

Redox electrocatalysis (catalysis of electron-transfer reactions by floating conductive particles) is discussed from the point-of-view of Fermi level equilibration, and an overall theoretical framework is given. Examples of redox electrocatalysis in solution, in bipolar configuration, and at liquid-liquid interfaces are provided, highlighting that bipolar and liquid-liquid interfacial systems allow the study of the electrocatalytic properties of particles without effects from the support, but only liquid-liquid interfaces allow measurement of the electrocatalytic current directly. Additionally, photoinduced redox electrocatalysis will be of interest, for example, to achieve water splitting.

Quantification of the Mass Transfer at Fluid Interfaces in Microfluidic Channels

NASA Astrophysics Data System (ADS)

Wismeth, Carina; Manhart, Michael; Niessner, Reinhard; Baumann, Thomas

2017-04-01

Mass transfer rates at interfaces in a complex porous media are relevant in many environmental applications and control the functions of natural filter systems in subsurface environments. The mass transfer at fluid interfaces is associated with interface convection caused by local inhomogeneities in interface tension and hydrodynamic instabilities at the interface. If there is a surface tension gradient along the surface a shear stress jump is generated that results in fluid motion along the surface that is called Marangoni effect. These spontaneous convection currents can lead to an increased mass transfer of the transition component at the phase boundary and to an increased mixing of the phases. Therefore compensatory currents at the interface can have a significant influence on the subsurface transport of contaminants in the groundwater area, especially in the vadose zone. Using microfluidic channels and advanced experimental techniques it is possible to measure the fluid flow and mass transfer rates directly and to quantify the effect of the Marangoni convection on the mass transfer at interfaces between a non-aqueous liquid and water with high temporal and spatial resolution. The use of fluorescent particles as well as the recording and analysis of their trajectories is intended to visualize interfacial processes and to quantify the mass transfer at fluid phase boundaries. Concentration gradients at the interface are analysed by spectroscopic methods and allow an assessment of the enrichment and depletion at the phase boundaries. Extensive test series provide the experimental basis for quantifying and analysing the impact of the Marangoni effect on the mass transfer rates at interfaces in porous media in subsurface aquatic environments. Within this research project we concentrate on the effect of Marangoni convection on the mass transfer near an 1-octanol-water interface, which serves as a well defined proxy for non-aqueous phase liquids in porous media. Experiments and a numerical simulation are closely coupled to provide a generic data set with high reproducibility and used to obtain highly resolved three-dimensional data of mass transfer in two- and three-phase systems to foster the understanding of subsurface transport, especially in the vadose zone.

Solubility of structurally complicated materials: 3. Hair.

PubMed

Horvath, Ari L

2009-04-27

Hair is composed of proteins, lipids, water, and small amounts of trace elements. All proteins in animal and human bodies are built from permutations of amino acid molecules in a polypeptide string. The polypeptide chains of protein keratin are organized into filaments in hair cells. Hair is one of the most difficult proteins to digest or solubilize. Among the most common dissolving procedures for hair are acidic, alkaline, and enzymatic hydrolysis. For the analysis of hair, the solid samples are transferred by solubilization via digestion into a liquid phase. Small molecular solvents and molecules with hydrophobic groups appear to have higher affinity for hair. A good solvent attacks the disulfide bonds between cystine molecules and hydrates the hair shaft. Consequently, the hair becomes a jelly-like mass.

Botanical supplements: detecting the transition from ingredients to supplements

USDA-ARS?s Scientific Manuscript database

Methods were developed using flow injection mass spectrometry (FIMS) and chemometrics for the comparison of spectral similarities and differences of 3 botanical ingredients and their supplements: Echinacea purpurea aerial samples and solid and liquid supplements, E. purpurea root samples and solid s...

The potential of flow-through microdialysis for probing low-molecular weight organic anions in rhizosphere soil solution.

PubMed

Sulyok, Michael; Miró, Manuel; Stingeder, Gerhard; Koellensperger, Gunda

2005-08-01

In this paper, flow-through microdialysis is presented as a novel analytical tool for automatic sampling of low molecular weight organic anions (LMWOA), such as oxalate and citrate, in solid samples of environmental concern. The microsampling methodology involves the implantation of dedicated capillary-type probes offering unrivalled spatial resolution (ca. 200μm) in definite soil sites. These passive samplers are aimed at monitoring local processes, such as the release of organic acids occurring in the rhizosphere environment, in nearly real-time. The influence of chemical and physical variables (composition and flow rate of the perfusion liquid, ionic strength and pH of the outer medium and presence of metal ions therein) was assessed in vitro using liquid-phase assays. On the other hand, the resistance of the external solid medium to mass transfer, and the actual applicability of in vivo calibration methods were investigated using quartz sand as an inert model soil. Microdialysers furnished with 3cm long semipermeable tubular membranes were perfused with 0.01M NaNO 3 at a flow rate of 2.0μl/min, yielding dialysis recoveries ≥45% for both assayed LMWOAs in simulated background soil electrolyte solutions, and ≥24% in the interstitial liquid of complex solid samples. Full knowledge of the fate of LMWOAs in soils was obtained through the application of stimulus-response approaches that mimic the discrete exudation pulses of roots. Highly time-resolved microdialysates were used to discern readily available species such as free carboxylic anions and LMW metal-organic acid complexes from adsorbed, precipitated or mineralised analyte species in a variety of soil samples containing variable amounts of organic matter, exchangeable cations and different levels of metal pollution.

Nonequilibrium adiabatic molecular dynamics simulations of methane clathrate hydrate decomposition

NASA Astrophysics Data System (ADS)

Alavi, Saman; Ripmeester, J. A.

2010-04-01

Nonequilibrium, constant energy, constant volume (NVE) molecular dynamics simulations are used to study the decomposition of methane clathrate hydrate in contact with water. Under adiabatic conditions, the rate of methane clathrate decomposition is affected by heat and mass transfer arising from the breakup of the clathrate hydrate framework and release of the methane gas at the solid-liquid interface and diffusion of methane through water. We observe that temperature gradients are established between the clathrate and solution phases as a result of the endothermic clathrate decomposition process and this factor must be considered when modeling the decomposition process. Additionally we observe that clathrate decomposition does not occur gradually with breakup of individual cages, but rather in a concerted fashion with rows of structure I cages parallel to the interface decomposing simultaneously. Due to the concerted breakup of layers of the hydrate, large amounts of methane gas are released near the surface which can form bubbles that will greatly affect the rate of mass transfer near the surface of the clathrate phase. The effects of these phenomena on the rate of methane hydrate decomposition are determined and implications on hydrate dissociation in natural methane hydrate reservoirs are discussed.

Nonequilibrium adiabatic molecular dynamics simulations of methane clathrate hydrate decomposition.

PubMed

Alavi, Saman; Ripmeester, J A

2010-04-14

Nonequilibrium, constant energy, constant volume (NVE) molecular dynamics simulations are used to study the decomposition of methane clathrate hydrate in contact with water. Under adiabatic conditions, the rate of methane clathrate decomposition is affected by heat and mass transfer arising from the breakup of the clathrate hydrate framework and release of the methane gas at the solid-liquid interface and diffusion of methane through water. We observe that temperature gradients are established between the clathrate and solution phases as a result of the endothermic clathrate decomposition process and this factor must be considered when modeling the decomposition process. Additionally we observe that clathrate decomposition does not occur gradually with breakup of individual cages, but rather in a concerted fashion with rows of structure I cages parallel to the interface decomposing simultaneously. Due to the concerted breakup of layers of the hydrate, large amounts of methane gas are released near the surface which can form bubbles that will greatly affect the rate of mass transfer near the surface of the clathrate phase. The effects of these phenomena on the rate of methane hydrate decomposition are determined and implications on hydrate dissociation in natural methane hydrate reservoirs are discussed.

Rational and Efficient Preparative Isolation of Natural Products by MPLC-UV-ELSD based on HPLC to MPLC Gradient Transfer.

PubMed

Challal, Soura; Queiroz, Emerson Ferreira; Debrus, Benjamin; Kloeti, Werner; Guillarme, Davy; Gupta, Mahabir Prashad; Wolfender, Jean-Luc

2015-11-01

In natural product research, the isolation of biomarkers or bioactive compounds from complex natural extracts represents an essential step for de novo identification and bioactivity assessment. When pure natural products have to be obtained in milligram quantities, the chromatographic steps are generally labourious and time-consuming. In this respect, an efficient method has been developed for the reversed-phase gradient transfer from high-performance liquid chromatography to medium-performance liquid chromatography for the isolation of pure natural products at the level of tens of milligrams from complex crude natural extracts. The proposed method provides a rational way to predict retention behaviour and resolution at the analytical scale prior to medium-performance liquid chromatography, and guarantees similar performances at both analytical and preparative scales. The optimisation of the high-performance liquid chromatography separation and system characterisation allows for the prediction of the gradient at the medium-performance liquid chromatography scale by using identical stationary phase chemistries. The samples were introduced in medium-performance liquid chromatography using a pressure-resistant aluminium dry load cell especially designed for this study to allow high sample loading while maintaining a maximum achievable flow rate for the separation. The method has been validated with a mixture of eight natural product standards. Ultraviolet and evaporative light scattering detections were used in parallel for a comprehensive monitoring. In addition, post-chromatographic mass spectrometry detection was provided by high-throughput ultrahigh-performance liquid chromatography time-of-flight mass spectrometry analyses of all fractions. The processing of all liquid chromatography-mass spectrometry data in the form of an medium-performance liquid chromatography x ultra high-performance liquid chromatography time-of-flight mass spectrometry matrix enabled an efficient localisation of the compounds of interest in the generated fractions. The methodology was successfully applied for the separation of three different plant extracts that contain many diverse secondary metabolites. The advantages and limitations of this approach and the theoretical chromatographic background that rules such as liquid chromatography gradient transfer are presented from a practical viewpoint. Georg Thieme Verlag KG Stuttgart · New York.

Advanced subgrid-scale modeling for convection-dominated species transport at fluid interfaces with application to mass transfer from rising bubbles

NASA Astrophysics Data System (ADS)

Weiner, Andre; Bothe, Dieter

2017-10-01

This paper presents a novel subgrid scale (SGS) model for simulating convection-dominated species transport at deformable fluid interfaces. One possible application is the Direct Numerical Simulation (DNS) of mass transfer from rising bubbles. The transport of a dissolving gas along the bubble-liquid interface is determined by two transport phenomena: convection in streamwise direction and diffusion in interface normal direction. The convective transport for technical bubble sizes is several orders of magnitude higher, leading to a thin concentration boundary layer around the bubble. A true DNS, fully resolving hydrodynamic and mass transfer length scales results in infeasible computational costs. Our approach is therefore a DNS of the flow field combined with a SGS model to compute the mass transfer between bubble and liquid. An appropriate model-function is used to compute the numerical fluxes on all cell faces of an interface cell. This allows to predict the mass transfer correctly even if the concentration boundary layer is fully contained in a single cell layer around the interface. We show that the SGS-model reduces the resolution requirements at the interface by a factor of ten and more. The integral flux correction is also applicable to other thin boundary layer problems. Two flow regimes are investigated to validate the model. A semi-analytical solution for creeping flow is used to assess local and global mass transfer quantities. For higher Reynolds numbers ranging from Re = 100 to Re = 460 and Péclet numbers between Pe =104 and Pe = 4 ṡ106 we compare the global Sherwood number against correlations from literature. In terms of accuracy, the predicted mass transfer never deviates more than 4% from the reference values.

Enhancing gas-liquid mass transfer rates in non-newtonian fermentations by confining mycelial growth to microbeads in a bubble column

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gbewonyo, K.; Wang, D.I.C.

The performance of a penicillin fermentation was assessed in a laboratory-scale bubble column fermentor, with mycelial growth confined to the pore matrix of celite beads. Final cell densities of 29 g/L and penicillin titres of 5.5 g/L were obtained in the confined cell cultures. In comparison, cultures of free mycelial cells grown in the absence of beads experienced dissolved oxygen limitations in the bubble column, giving only 17 g/L final cell concentrations with equally low penicillin titres of 2 g/L. The better performance of the confined cell cultures was attributed to enhanced gas liquid mass transfer rates, with mass transfermore » coefficients (k /SUB L/ a) two to three times higher than those determined in the free cell cultures. Furthermore, the confined cell cultures showed more efficient utilization of power input for mass transfer, providing up to 50% reduction in energy requirements for aeration.« less

Numerical modeling of self-pressurization and pressure control by a thermodynamic vent system in a cryogenic tank

NASA Astrophysics Data System (ADS)

Majumdar, Alok; Valenzuela, Juan; LeClair, Andre; Moder, Jeff

2016-03-01

This paper presents a numerical model of a system-level test bed-the multipurpose hydrogen test bed (MHTB) using the Generalized Fluid System Simulation Program (GFSSP). MHTB is representative in size and shape of a space transportation vehicle liquid hydrogen propellant tank, and ground-based testing was performed at NASA Marshall Space Flight Center (MSFC) to generate data for cryogenic storage. GFSSP is a finite volume-based network flow analysis software developed at MSFC and used for thermofluid analysis of propulsion systems. GFSSP has been used to model the self-pressurization and ullage pressure control by the Thermodynamic Vent System (TVS). A TVS typically includes a Joule-Thompson (J-T) expansion device, a two-phase heat exchanger (HEX), and a mixing pump and liquid injector to extract thermal energy from the tank without significant loss of liquid propellant. For the MHTB tank, the HEX and liquid injector are combined into a vertical spray bar assembly. Two GFSSP models (Self-Pressurization and TVS) were separately developed and tested and then integrated to simulate the entire system. The Self-Pressurization model consists of multiple ullage nodes, a propellant node, and solid nodes; it computes the heat transfer through multilayer insulation blankets and calculates heat and mass transfer between the ullage and liquid propellant and the ullage and tank wall. A TVS model calculates the flow through a J-T valve, HEX, and spray and vent systems. Two models are integrated by exchanging data through User Subroutines of both models. Results of the integrated models have been compared with MHTB test data at a 50% fill level. Satisfactory comparison was observed between tests and numerical predictions.

Determination of boldenone sulfoconjugate and related steroid sulfates in equine urine by high-performance liquid chromatography/tandem mass spectrometry.

PubMed

Weidolf, L O; Lee, E D; Henion, J D

1988-03-01

Sulfoconjugated anabolic steroids were separated by micro-bore high-performance liquid chromatography. The eluent was introduced into the atmospheric pressure ion source of the triple-quadrupole mass spectrometer via an ion spray liquid chromatograph/mass spectrometer interface operated in the negative ion mode. The limit of detection was 10 pg on-column by selected ion monitoring of the molecular ion and the response increased linearly over a concentration range of 2.4 orders of magnitude. Following work-up by a liquid-solid extraction procedure of equine urine samples, full-scan daughter ion spectra of boldenone sulfate could be obtained up to 17 days after a therapeutic dose of boldenone undecylenate to a horse.

Effect of surfactant on single drop mass transfer for extraction of aromatics from lubricating oils

NASA Astrophysics Data System (ADS)

Izza, H.; Ben Abdessalam, S.; Korichi, M.

2018-03-01

Solvent extraction is an effective method for the reduction of the content of aromatic of lubricating oil. Frequently, with phenol, furfural, the NMP (out of N-methyl pyrrolidone). The power solvent and the selectivity can be still to increase while using surfactant as additive which facilitates the separation of phase and increases the yeild in raffinat. Liquid-liquid mass transfer coefficients for single freely rising drops in the presence of surfactant in an extraction column have been investigated. The surfactant used in this study was sodium lauryl ether sulfate (SLES). The experiments were performed by bubbling a solvent as a series of individual drops from the top of the column containing furfural-SLES solution. The column used in this experiment was made from glass with 17 mm inner diameter and a capacity of 125ml. The effects of the concentration of surfactant on the overall coefficient of mass transfer was investigated.

A high-power ultrasonic microreactor and its application in gas-liquid mass transfer intensification.

PubMed

Dong, Zhengya; Yao, Chaoqun; Zhang, Xiaoli; Xu, Jie; Chen, Guangwen; Zhao, Yuchao; Yuan, Quan

2015-02-21

The combination of ultrasound and microreactor is an emerging and promising area, but the report of designing high-power ultrasonic microreactor (USMR) is still limited. This work presents a robust, high-power and highly efficient USMR by directly coupling a microreactor plate with a Langevin-type transducer. The USMR is designed as a longitudinal half wavelength resonator, for which the antinode plane of the highest sound intensity is located at the microreactor. According to one dimension design theory, numerical simulation and impedance analysis, a USMR with a maximum power of 100 W and a resonance frequency of 20 kHz was built. The strong and uniform sound field in the USMR was then applied to intensify gas-liquid mass transfer of slug flow in a microfluidic channel. Non-inertial cavitation with multiple surface wave oscillation was excited on the slug bubbles, enhancing the overall mass transfer coefficient by 3.3-5.7 times.

One-dimensional analysis of plane and radial thin film flows including solid-body rotation

NASA Technical Reports Server (NTRS)

Thomas, S.; Hankey, W.; Faghri, A.; Swanson, T.

1989-01-01

The flow of a thin liquid film with a free surface along a horizontal plate which emanates from a pressurized vessel is examined by integrating the equations of motion across the thin liquid layer and discretizing the integrated equations using finite difference techniques. The effects of 0-g and solid-body rotation will be discussed. The two cases of interest are plane flow and radial flow. In plane flow, the liquid is considered to be flowing along a channel with no change in the width of the channel, whereas in radial flow the liquid spreads out radially over a disk, so that the area changes along the radius. It is desired to determine the height of the liquid film at any location along the plate of disk, so that the heat transfer from the plate or disk can be found. The possibility that the flow could encounter a hydraulic jump is accounted for.

Equilibrium lithium-ion transport between nanocrystalline lithium-inserted anatase TiO2 and the electrolyte.

PubMed

Ganapathy, Swapna; van Eck, Ernst R H; Kentgens, Arno P M; Mulder, Fokko M; Wagemaker, Marnix

2011-12-23

The power density of lithium-ion batteries requires the fast transfer of ions between the electrode and electrolyte. The achievable power density is directly related to the spontaneous equilibrium exchange of charged lithium ions across the electrolyte/electrode interface. Direct and unique characterization of this charge-transfer process is very difficult if not impossible, and consequently little is known about the solid/liquid ion transfer in lithium-ion-battery materials. Herein we report the direct observation by solid-state NMR spectroscopy of continuous lithium-ion exchange between the promising nanosized anatase TiO(2) electrode material and the electrolyte. Our results reveal that the energy barrier to charge transfer across the electrode/electrolyte interface is equal to or greater than the barrier to lithium-ion diffusion through the solid anatase matrix. The composition of the electrolyte and in turn the solid/electrolyte interface (SEI) has a significant effect on the electrolyte/electrode lithium-ion exchange; this suggests potential improvements in the power of batteries by optimizing the electrolyte composition. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of accelerated crucible rotation on melt composition in high-pressure vertical Bridgman growth of cadmium zinc telluride

NASA Astrophysics Data System (ADS)

Yeckel, Andrew; Derby, Jeffrey J.

2000-02-01

Three-dimensional axisymmetric, time-dependent simulations of the high-pressure vertical Bridgman growth of large-diameter cadmium zinc telluride are performed to study the effect of accelerated crucible rotation (ACRT) on crystal growth dynamics. The model includes details of heat transfer, melt convection, solid-liquid interface shape, and dilute zinc segregation. Application of ACRT greatly improves mixing in the melt, but causes an overall increased deflection of the solid-liquid interface. The flow exhibits a Taylor-Görtler instability at the crucible sidewall, which further enhances melt mixing. The rate of mixing depends strongly on the length of the ACRT cycle, with an optimum half-cycle length between 2 and 4 Ekman time units. Significant melting of the crystal occurs during a portion of the rotation cycle, caused by periodic reversal of the secondary flow at the solid-liquid interface, indicating the possibility of compositional striations.

Evaluation of ionic liquids supported on silica as a sorbent for fully automated online solid-phase extraction with LC-MS determination of sulfonamides in bovine milk samples.

PubMed

da Silva, Meire Ribeiro; Mauro Lanças, Fernando

2018-03-10

Sulfonamides are antibiotics widely used in the treatment of diseases in dairy cattle. However, their indiscriminate use for disease control may lead to their presence in tissues and milk and their determination requires a sample preparation step as part of an analytical approach. Among the several sample preparation techniques available, those based upon the use of sorptive materials have been widely employed. Recently, the application of ionic liquids immobilized on silica surfaces or polymeric materials has been evaluated for such an application. This manuscript addresses the evaluation of silica-based ionic liquid obtained by a sol-gel synthesis process by basic catalysis as sorbent for online solid-phase extraction with liquid chromatography and electrospray ionization time-of-flight mass spectrometry for sulfonamides determination. Infrared vibrational spectroscopy confirmed the presence of the ionic liquid on the silica surface, suggesting that the ionic liquid was anchored on to the silica surface. Other sorbents varying the ionic liquid alkyl chain were also synthesized and evaluated by off-line solid-phase extraction in the sulfonamide extraction. As the length of the alkyl chain increased, the amount of extracted sulfonamides decreased, possibly due to a decrease in the electrostatic interaction caused by the reduction in the polarity, as well as the presence of a hexafluorophosphate anion that increases the hydrophobic character of the material. The use of 1-butyl-3-methylimidazolium hexafluorophosphate as a selective ionic liquid sorbent enabled the isolation and sulfonamide preconcentration in bovine milk by online solid-phase extraction with liquid chromatography and electrospray ionization time-of-flight mass spectrometry. The limit of quantification for the method developed was 5-7, 5 μg/mL, with extraction recoveries ranging between 74 and 93% and intra- and interassay between 1.5-12.5 and 2.3-13.1, respectively. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Waste Management Project fiscal year 1998 multi-year work plan, WBS 1.2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jacobsen, P.H.

The Waste Management Project manages and integrates (non-TWRS) waste management activities at the site. Activities include management of Hanford wastes as well as waste transferred to Hanford from other DOE, Department of Defense, or other facilities. This work includes handling, treatment, storage, and disposal of radioactive, nonradioactive, hazardous, and mixed solid and liquid wastes. Major Waste Management Projects are the Solid Waste Project, Liquid Effluents Project, and Analytical Services. Existing facilities (e.g., grout vaults and canyons) shall be evaluated for reuse for these purposes to the maximum extent possible.

Analysis of close-contact melting with inner wall temperature variation in a horizontal cylindrical capsule

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saitoh, T.S.; Hoshi, Akira

1997-12-31

Melting and solidification of a phase change material (PCM) in a capsule is of practical importance in latent heat thermal energy storage (LHTES) systems which are considered to be very promising to reduce a peak demand of electricity in the summer season. Two melting modes are involved in melting in capsules. One is close-contact melting between the solid bulk and the capsule wall, and another is natural convection melting in the liquid region. In recent years, close-contact melting processes for a single enclosure have been solved using several numerical methods (e.g., Saitoh and Kato (1994)). However, there is no theoreticalmore » solution considering the inner wall temperature variation within cylindrical or spherical capsules. In this report close-contact melting heat transfer characteristics including melt flow in the liquid film under inner wall temperature distribution were analyzed and simple approximate equations are presented, which facilitates designing of the practical capsule bed LHTES systems. The effects of Stefan number and variable temperature profile etc. were clarified in detail. And the melting velocity of the solid bulk under various conditions was also studied theoretically. In addition, the effects of variable inner wall temperature on molten mass fraction were investigated.« less

Insertion and confinement of hydrophobic metallic powder in water: the bubble-marble effect.

PubMed

Meir, Yehuda; Jerby, Eli

2014-09-01

Metallic powders such as thermite are known as efficient fuels also applicable in oxygen-free environments. However, due to their hydrophobicity, they hardly penetrate into water. This paper presents an effect that enables the insertion and confinement of hydrophobic metallic powders in water, based on encapsulating an air bubble surrounded by a hydrophobic metallic shell. This effect, regarded as an inverse of the known liquid-marble effect, is named here "bubble marble" (BM). The sole BM is demonstrated experimentally as a stable, maneuverable, and controllable soft-solid-like structure, in a slightly deformed hollow spherical shape of ∼1-cm diameter. In addition to experimental and theoretical BM aspects, this paper also demonstrates its potential for underwater applications, such as transportation of solid objects within BM and underwater combustion of thermite BM by localized microwaves. Hence, the BM phenomena may open new possibilities for heat and thrust generation, as well as material processing and mass transfer underwater.

Insertion and confinement of hydrophobic metallic powder in water: The bubble-marble effect

NASA Astrophysics Data System (ADS)

Meir, Yehuda; Jerby, Eli

2014-09-01

Metallic powders such as thermite are known as efficient fuels also applicable in oxygen-free environments. However, due to their hydrophobicity, they hardly penetrate into water. This paper presents an effect that enables the insertion and confinement of hydrophobic metallic powders in water, based on encapsulating an air bubble surrounded by a hydrophobic metallic shell. This effect, regarded as an inverse of the known liquid-marble effect, is named here "bubble marble" (BM). The sole BM is demonstrated experimentally as a stable, maneuverable, and controllable soft-solid-like structure, in a slightly deformed hollow spherical shape of ˜1-cm diameter. In addition to experimental and theoretical BM aspects, this paper also demonstrates its potential for underwater applications, such as transportation of solid objects within BM and underwater combustion of thermite BM by localized microwaves. Hence, the BM phenomena may open new possibilities for heat and thrust generation, as well as material processing and mass transfer underwater.

Solid versus Liquid Particle Sampling Efficiency of Three Personal Aerosol Samplers when Facing the Wind

PubMed Central

Koehler, Kirsten A.; Anthony, T. Renee; Van Dyke, Michael

2016-01-01

The objective of this study was to examine the facing-the-wind sampling efficiency of three personal aerosol samplers as a function of particle phase (solid versus liquid). Samplers examined were the IOM, Button, and a prototype personal high-flow inhalable sampler head (PHISH). The prototype PHISH was designed to interface with the 37-mm closed-face cassette and provide an inhalable sample at 10 l min−1 of flow. Increased flow rate increases the amount of mass collected during a typical work shift and helps to ensure that limits of detection are met, particularly for well-controlled but highly toxic species. Two PHISH prototypes were tested: one with a screened inlet and one with a single-pore open-face inlet. Personal aerosol samplers were tested on a bluff-body disc that was rotated along the facing-the-wind axis to reduce spatiotemporal variability associated with sampling supermicron aerosol in low-velocity wind tunnels. When compared to published data for facing-wind aspiration efficiency for a mouth-breathing mannequin, the IOM oversampled relative to mannequin facing-the-wind aspiration efficiency for all sizes and particle types (solid and liquid). The sampling efficiency of the Button sampler was closer to the mannequin facing-the-wind aspiration efficiency than the IOM for solid particles, but the screened inlet removed most liquid particles, resulting in a large underestimation compared to the mannequin facing-the-wind aspiration efficiency. The open-face PHISH results showed overestimation for solid particles and underestimation for liquid particles when compared to the mannequin facing-the-wind aspiration efficiency. Substantial (and statistically significant) differences in sampling efficiency were observed between liquid and solid particles, particularly for the Button and screened-PHISH, with a majority of aerosol mass depositing on the screened inlets of these samplers. Our results suggest that large droplets have low penetration efficiencies through screened inlets and that particle bounce, for solid particles, is an important determinant of aspiration and sampling efficiencies for samplers with screened inlets. PMID:21965462

Liquid carry-over in an injection moulded all-polymer chip system for immiscible phase magnetic bead-based solid-phase extraction

NASA Astrophysics Data System (ADS)

Kistrup, Kasper; Skotte Sørensen, Karen; Wolff, Anders; Fougt Hansen, Mikkel

2015-04-01

We present an all-polymer, single-use microfluidic chip system produced by injection moulding and bonded by ultrasonic welding. Both techniques are compatible with low-cost industrial mass-production. The chip is produced for magnetic bead-based solid-phase extraction facilitated by immiscible phase filtration and features passive liquid filling and magnetic bead manipulation using an external magnet. In this work, we determine the system compatibility with various surfactants. Moreover, we quantify the volume of liquid co-transported with magnetic bead clusters from Milli-Q water or a lysis-binding buffer for nucleic acid extraction (0.1 (v/v)% Triton X-100 in 5 M guanidine hydrochloride). A linear relationship was found between the liquid carry-over and mass of magnetic beads used. Interestingly, similar average carry-overs of 1.74(8) nL/μg and 1.72(14) nL/μg were found for Milli-Q water and lysis-binding buffer, respectively.

Finite Element Multi-scale Modeling of Chemical Segregation in Steel Solidification Taking into Account the Transport of Equiaxed Grains

NASA Astrophysics Data System (ADS)

Nguyen, Thi-Thuy-My; Gandin, Charles-André; Combeau, Hervé; Založnik, Miha; Bellet, Michel

2018-02-01

The transport of solid crystals in the liquid pool during solidification of large ingots is known to have a significant effect on their final grain structure and macrosegregation. Numerical modeling of the associated physics is challenging since complex and strong interactions between heat and mass transfer at the microscopic and macroscopic scales must be taken into account. The paper presents a finite element multi-scale solidification model coupling nucleation, growth, and solute diffusion at the microscopic scale, represented by a single unique grain, while also including transport of the liquid and solid phases at the macroscopic scale of the ingots. The numerical resolution is based on a splitting method which sequentially describes the evolution and interaction of quantities into a transport and a growth stage. This splitting method reduces the non-linear complexity of the set of equations and is, for the first time, implemented using the finite element method. This is possible due to the introduction of an artificial diffusion in all conservation equations solved by the finite element method. Simulations with and without grain transport are compared to demonstrate the impact of solid phase transport on the solidification process as well as the formation of macrosegregation in a binary alloy (Sn-5 wt pct Pb). The model is also applied to the solidification of the binary alloy Fe-0.36 wt pct C in a domain representative of a 3.3-ton steel ingot.

Hypervelocity Launching and Frozen Fuels as a Major Contribution to Spaceflight

NASA Astrophysics Data System (ADS)

Cocks, F. H.; Harman, C. M.; Klenk, P. A.; Simmons, W. N.

Acting as a virtual first stage, a hypervelocity launch together with the use of frozen hydrogen/frozen oxygen propellant, offers a Single-Stage-To-Orbit (SSTO) system that promises an enormous increase in SSTO mass-ratio. Ram acceleration provides hypervelocity (2 km/sec) to the orbital vehicle with a gas gun supplying the initial velocity required for ram operation. The vehicle itself acts as the center body of a ramjet inside a launch tube, filled with gaseous fuel and oxidizer, acting as an engine cowling. The high acceleration needed to achieve hypervelocity precludes a crew, and it would require greatly increased liquid fuel tank structural mass if a liquid propellant is used for post-launch vehicle propulsion. Solid propellants do not require as much fuel- chamber strengthening to withstand a hypervelocity launch as do liquid propellants, but traditional solid fuels have lower exhaust velocities than liquid hydrogen/liquid oxygen. The shock-stability of frozen hydrogen/frozen oxygen propellant has been experimentally demonstrated. A hypervelocity launch system using frozen hydrogen/frozen oxygen propellant would be a revolutionary new development in spaceflight.

Hydrodynamics, mass transfer, and yeast culture performance of a column bioreactor with ejector.

PubMed

Prokop, A; Janík, P; Sobotka, M; Krumphanzl, V

1983-04-01

A bubble column fitted with an ejector has been tested for its physical and biological performance. The axial diffusion coefficient of the liquid phase in the presence of electrolytes and ethanol was measured by a stimulus-response technique with subsequent evaluation by means of a diffusion model. In contrast to ordinary bubble columns, the coefficient of axial mixing is inversely dependent on the superficial air velocity. The liquid velocity acts in an opposite direction to the backmixing flow in the column. The measurement of volumetric oxygen transfer coefficient in the presence of electrolytes and ethanol was performed using a dynamic gassing-in method adapted for a column. The data were correlated with the superficial air and liquid velocities, total power input, and power for aeration and mixing; the economy coefficient of oxygen transfer was used for finding an optimum ratio of power for aeration and pumping. Growth experiments with Candida utilis on ethanol confirmed some of the above results. Biomass productivity of 2.5 g L(-1) h(-1) testifies about a good transfer capability of the column. Columns fitted with pneumatic and/or hydraulic energy input may be promising for aerobic fermentations considering their mass transfer and mixing characteristics.

Analytical strategies for organic food packaging contaminants.

PubMed

Sanchis, Yovana; Yusà, Vicent; Coscollà, Clara

2017-03-24

In this review, we present current approaches in the analysis of food-packaging contaminants. Gas and liquid chromatography coupled to mass spectrometry detection have been widely used in the analysis of some relevant families of these compounds such as primary aromatic amines, bisphenol A, bisphenol A diglycidyl ether and related compounds, UV-ink photoinitiators, perfluorinated compounds, phthalates and non-intentionally added substances. Main applications for sample treatment and different types of food-contact material migration studies have been also discussed. Pressurized Liquid Extraction, Solid-Phase Microextraction, Focused Ultrasound Solid-Liquid Extraction and Quechers have been mainly used in the extraction of food contact material (FCM) contaminants, due to the trend of minimising solvent consumption, automatization of sample preparation and integration of extraction and clean-up steps. Recent advances in analytical methodologies have allowed unequivocal identification and confirmation of these contaminants using Liquid Chromatography coupled to High Resolution Mass Spectrometry (LC-HRMS) through mass accuracy and isotopic pattern applying. LC-HRMS has been used in the target analysis of primary aromatic amines in different plastic materials, but few studies have been carried out applying this technique in post-target and non-target analysis of FCM contaminants. Copyright © 2017 Elsevier B.V. All rights reserved.

Numerical simulation of heat and mass transport during space crystal growth with MEPHISTO

NASA Technical Reports Server (NTRS)

Yao, Minwu; Raman, Raghu; Degroh, Henry C., III

1995-01-01

The MEPHISTO space experiments are collaborative United States and French investigations aimed at understanding the fundamentals of crystal growth. Microgravity experiments were conducted aboard the USMP-1 and -2 missions on STS-52 and 62 in October 1992 and March 1994 respectively. MEPHISTO is a French designed and built Bridgman type furnace which uses the Seebeck technique to monitor the solid/liquid interface temperature and Peltier pulsing to mark the location and shape of the solid/liquid interface. In this paper the Bridgman growth of Sn-Bi and Bi-Sn under terrestrial and microgravity conditions is modeled using the finite element code, FIDAP*. The numerical model considers fully coupled heat and mass transport, fluid motion and solid/liquid phase changes in the crystal growth process. The primary goals of this work are: to provide a quantitative study of the thermal buoyancy-induced convection in the melt for the two flight experiments; to compare the vertical and horizontal growth configurations and systematically evaluate the effects of various gravity levels on the solute segregation. Numerical results of the vertical and horizontal Bridgman growth configurations are presented.

Behavior of fluids in a weightless environment

NASA Technical Reports Server (NTRS)

Fester, D. A.; Eberhardt, R. N.; Tegart, J. R.

1977-01-01

Fluid behavior in a low-g environment is controlled primarily by surface tension forces. Certain fluid and system characteristics determine the magnitude of these forces for both a free liquid surface and liquid in contact with a solid. These characteristics, including surface tension, wettability or contact angle, system geometry, and the relationships governing their interaction, are discussed. Various aspects of fluid behavior in a low-g environment are then presented. This includes the formation of static interface shapes, oscillation and rotation of drops, coalescence, the formation of foams, tendency for cavitation, and diffusion in liquids which were observed during the Skylab fluid mechanics science demonstrations. Liquid reorientation and capillary pumping to establish equilibrium configurations for various system geometries, observed during various free-fall (drop-tower) low-g tests, are also presented. Several passive low-g fluid storage and transfer systems are discussed. These systems use surface tension forces to control the liquid/vapor interface and provide gas-free liquid transfer and liquid-free vapor venting.

An experimental investigation of the effects of spiral angle on the evaporation heat transfer coefficients in microfin tubes with visualization technique

NASA Astrophysics Data System (ADS)

Oh, Se-Yoon

A smooth tube and five microfin tubes were tested, and evaporation heat transfer coefficients were measured and compared for mass fluxes, 50, 100 and 200 kg/m2 s, and heat fluxes, 5, 10 and 20 kW/m 2, with Refrigerant 134a as a working fluid. The evaporation heat transfer coefficients at quality 0.5 were compared among the smooth and five microfin tubes with spiral angles 6, 12, 18, 25 and 44 degrees. The effect of the spiral angle on the heat transfer coefficients was examined. It was found that the optimal spiral angle where the maximum heat transfer coefficient occurs, mainly depends on mass flux. The optimal spiral angle was 18 degrees for G=50 kg/m2 s, and 6 degrees for G=100 and 200 kg/m 2 s. A borescope was used to visualize the flow on the inside wall of test tubes. The purpose was to find out the effect of the grooves on the liquid flow in microfin tubes and to explain the mechanism of heat transfer enhancement. Temperatures on the tube wall were measured at the same axial location as the imaging sensor of the borescope, and were related to the behavior of the liquid flow on the inside wall of the tubes. The liquid flow in the grooves on the wall was found to be the most important factor in enhancing heat transfer coefficients. The liquid flowed upward along the grooves and covered the upper inside wall of the microfin tubes at G=50 kg/m2 s. When heat flux increases, the liquid flow was found at a higher position. Both liquid viscosity and surface tension decrease, when temperature increases. Thus, the lower viscosity at higher heat flux facilitated the upward motion of the liquid flow in the grooves, so that the momentum force as well as the capillary effect was found to push the liquid along the grooves.* *A CD is included with dissertation containing video clips in avi format which can be viewed with media player.

Two-dimensional model of a Space Station Freedom thermal energy storage canister

NASA Astrophysics Data System (ADS)

Kerslake, Thomas W.; Ibrahim, Mounir B.

1990-08-01

The Solar Dynamic Power Module being developed for Space Station Freedom uses a eutectic mixture of LiF-CaF2 phase change salt contained in toroidal canisters for thermal energy storage. Results are presented from heat transfer analyses of the phase change salt containment canister. A 2-D, axisymmetric finite difference computer program which models the canister walls, salt, void, and heat engine working fluid coolant was developed. Analyses included effects of conduction in canister walls and solid salt, conduction and free convection in liquid salt, conduction and radiation across salt vapor filled void regions and forced convection in the heat engine working fluid. Void shape, location, growth or shrinkage (due to density difference between the solid and liquid salt phases) were prescribed based on engineering judgement. The salt phase change process was modeled using the enthalpy method. Discussion of results focuses on the role of free-convection in the liquid salt on canister heat transfer performance. This role is shown to be important for interpreting the relationship between ground based canister performance (in l-g) and expected on-orbit performance (in micro-g). Attention is also focused on the influence of void heat transfer on canister wall temperature distributions. The large thermal resistance of void regions is shown to accentuate canister hot spots and temperature gradients.

Two-dimensional model of a Space Station Freedom thermal energy storage canister

NASA Astrophysics Data System (ADS)

Kerslake, Thomas W.; Ibrahim, Mounir B.

The Solar Dynamic Power Module being developed for Space Station Freedom uses a eutectic mixture of LiF-CaF2 phase change salt contained in toroidal canisters for thermal energy storage. Results are presented from heat transfer analyses of the phase-change salt containment canister. A 2-D, axisymmetric finite-difference computer program which models the canister walls, salt, void, and heat engine working fluid coolant was developed. Analyses included effects of conduction in canister walls and solid salt, conduction and free convection in liquid salt, conduction and radiation across salt vapor filled void regions, and forced convection in the heat engine working fluid. Void shape, location, and growth or shrinkage (due to density difference between the solid and liquid salt phases) were prescribed based on engineering judgement. The salt phase change process was modeled using the enthalpy method. Discussion of results focuses on the role of free-convection in the liquid salt on canister heat transfer performance. This role is shown to be important for interpreting the relationship between groundbased canister performance (in 1-g) and expected on-orbit performance (in micro-g). Attention is also focused on the influence of void heat transfer on canister wall temperature distributions. The large thermal resistance of void regions is shown to accentuate canister hot spots and temperature gradients.

Two-dimensional model of a Space Station Freedom thermal energy storage canister

NASA Technical Reports Server (NTRS)

Kerslake, Thomas W.; Ibrahim, Mounir B.

1990-01-01

The Solar Dynamic Power Module being developed for Space Station Freedom uses a eutectic mixture of LiF-CaF2 phase change salt contained in toroidal canisters for thermal energy storage. Results are presented from heat transfer analyses of the phase-change salt containment canister. A 2-D, axisymmetric finite-difference computer program which models the canister walls, salt, void, and heat engine working fluid coolant was developed. Analyses included effects of conduction in canister walls and solid salt, conduction and free convection in liquid salt, conduction and radiation across salt vapor filled void regions, and forced convection in the heat engine working fluid. Void shape, location, and growth or shrinkage (due to density difference between the solid and liquid salt phases) were prescribed based on engineering judgement. The salt phase change process was modeled using the enthalpy method. Discussion of results focuses on the role of free-convection in the liquid salt on canister heat transfer performance. This role is shown to be important for interpreting the relationship between groundbased canister performance (in 1-g) and expected on-orbit performance (in micro-g). Attention is also focused on the influence of void heat transfer on canister wall temperature distributions. The large thermal resistance of void regions is shown to accentuate canister hot spots and temperature gradients.

Two-dimensional model of a Space Station Freedom thermal energy storage canister

NASA Technical Reports Server (NTRS)

Kerslake, Thomas W.; Ibrahim, Mounir B.

1990-01-01

The Solar Dynamic Power Module being developed for Space Station Freedom uses a eutectic mixture of LiF-CaF2 phase change salt contained in toroidal canisters for thermal energy storage. Results are presented from heat transfer analyses of the phase change salt containment canister. A 2-D, axisymmetric finite difference computer program which models the canister walls, salt, void, and heat engine working fluid coolant was developed. Analyses included effects of conduction in canister walls and solid salt, conduction and free convection in liquid salt, conduction and radiation across salt vapor filled void regions and forced convection in the heat engine working fluid. Void shape, location, growth or shrinkage (due to density difference between the solid and liquid salt phases) were prescribed based on engineering judgement. The salt phase change process was modeled using the enthalpy method. Discussion of results focuses on the role of free-convection in the liquid salt on canister heat transfer performance. This role is shown to be important for interpreting the relationship between ground based canister performance (in l-g) and expected on-orbit performance (in micro-g). Attention is also focused on the influence of void heat transfer on canister wall temperature distributions. The large thermal resistance of void regions is shown to accentuate canister hot spots and temperature gradients.

Heat transfer process during the crystallization of benzil grown by the Bridgman-Stockbarger method

NASA Astrophysics Data System (ADS)

Barvinschi, F.; Stanculescu, A.; Stanculescu, F.

2011-02-01

The temperature distribution and solid-liquid interface shape during benzil growth have been studied both experimentally and numerically. The heat transfer equation with appropriate boundary conditions has been solved by modelling a vertical Bridgman-Stockbarger growth configuration. Two models have been developed, namely a global numerical model and a pseudo-transient approximation in an ideal configuration.

Heat transfer simulation in a vertical Bridgman CdTe growth configuration

NASA Astrophysics Data System (ADS)

Martinez-Tomas, C.; Muñoz, V.; Triboulet, R.

1999-02-01

Modelling and numerical simulation of crystal growth processes have been shown to be powerful tools in order to understand the physical effects of different parameters on the growth conditions. In this study a finite difference/control volume technique for the study of heat transfer has been employed. This model takes into account the whole system: furnace temperature profile, air gap between furnace walls and ampoule, ampoule geometry, crucible coating if any, solid and liquid CdTe thermal properties, conduction, convection and radiation of heat and phase change. We have used the commercial code FLUENT for the numerical resolution that can be running on a personal computer. Results show that the temperature field is very sensitive to the charge and ampoule peculiarities. As a consequence, significant differences between the velocity of the ampoule and that of the isotherm determining the solid/liquid interface have been found at the onset of the growth.

Application of the two-film model to the volatilization of acetone and t-butyl alcohol from water as a function of temperature

USGS Publications Warehouse

Rathbun, R.E.; Tai, D.Y.

1988-01-01

The two-film model is often used to describe the volatilization of organic substances from water. This model assumes uniformly mixed water and air phases separated by thin films of water and air in which mass transfer is by molecular diffusion. Mass-transfer coefficients for the films, commonly called film coefficients, are related through the Henry's law constant and the model equation to the overall mass-transfer coefficient for volatilization. The films are modeled as two resistances in series, resulting in additive resistances. The two-film model and the concept of additivity of resistances were applied to experimental data for acetone and t-butyl alcohol. Overall mass-transfer coefficients for the volatilization of acetone and t-butyl alcohol from water were measured in the laboratory in a stirred constant-temperature bath. Measurements were completed for six water temperatures, each at three water mixing conditions. Wind-speed was constant at about 0.1 meter per second for all experiments. Oxygen absorption coefficients were measured simultaneously with the measurement of the acetone and t-butyl alcohol mass-transfer coefficients. Gas-film coefficients for acetone, t-butyl alcohol, and water were determined by measuring the volatilization fluxes of the pure substances over a range of temperatures. Henry's law constants were estimated from data from the literature. The combination of high resistance in the gas film for solutes with low values of the Henry's law constants has not been studied previously. Calculation of the liquid-film coefficients for acetone and t-butyl alcohol from measured overall mass-transfer and gas-film coefficients, estimated Henry's law constants, and the two-film model equation resulted in physically unrealistic, negative liquid-film coefficients for most of the experiments at the medium and high water mixing conditions. An analysis of the two-film model equation showed that when the percentage resistance in the gas film is large and the gas-film resistance approaches the overall resistance in value, the calculated liquid-film coefficient becomes extremely sensitive to errors in the Henry's law constant. The negative coefficients were attributed to this sensitivity and to errors in the estimated Henry's law constants. Liquid-film coefficients for the absorption of oxygen were correlated with the stirrer Reynolds number and the Schmidt number. Application of this correlation with the experimental conditions and a molecular-diffusion coefficient adjustment resulted in values of the liquid-film coefficients for both acetone and t-butyl alcohol within the range expected for all three mixing conditions. Comparison of Henry's law constants calculated from these film coefficients and the experimental data with the constants calculated from literature data showed that the differences were small relative to the errors reported in the literature as typical for the measurement or estimation of Henry's law constants for hydrophilic compounds such as ketones and alcohols. Temperature dependence of the mass-transfer coefficients was expressed in two forms. The first, based on thermodynamics, assumed the coefficients varied as the exponential of the reciprocal absolute temperature. The second empirical approach assumed the coefficients varied as the exponential of the absolute temperature. Both of these forms predicted the temperature dependence of the experimental mass-transfer coefficients with little error for most of the water temperature range likely to be found in streams and rivers. Liquid-film and gas-film coefficients for acetone and t-butyl alcohol were similar in value. However, depending on water mixing conditions, overall mass-transfer coefficients for acetone were from two to four times larger than the coefficients for t-butyl alcohol. This difference in behavior of the coefficients resulted because the Henry's law constant for acetone was about three times larger than that of

Physics of microstructures enhancement of thin film evaporation heat transfer in microchannels flow boiling

PubMed Central

Bigham, Sajjad; Fazeli, Abdolreza; Moghaddam, Saeed

2017-01-01

Performance enhancement of the two-phase flow boiling heat transfer process in microchannels through implementation of surface micro- and nanostructures has gained substantial interest in recent years. However, the reported results range widely from a decline to improvements in performance depending on the test conditions and fluid properties, without a consensus on the physical mechanisms responsible for the observed behavior. This gap in knowledge stems from a lack of understanding of the physics of surface structures interactions with microscale heat and mass transfer events involved in the microchannel flow boiling process. Here, using a novel measurement technique, the heat and mass transfer process is analyzed within surface structures with unprecedented detail. The local heat flux and dryout time scale are measured as the liquid wicks through surface structures and evaporates. The physics governing heat transfer enhancement on textured surfaces is explained by a deterministic model that involves three key parameters: the drying time scale of the liquid film wicking into the surface structures (τd), the heating length scale of the liquid film (δH) and the area fraction of the evaporating liquid film (Ar). It is shown that the model accurately predicts the optimum spacing between surface structures (i.e. pillars fabricated on the microchannel wall) in boiling of two fluids FC-72 and water with fundamentally different wicking characteristics. PMID:28303952

The effect of microbubbles on gas-liquid mass transfer coefficient and degradation rate of COD in wastewater treatment.

PubMed

Yao, Kangning; Chi, Yong; Wang, Fei; Yan, Jianhua; Ni, Mingjiang; Cen, Kefa

2016-01-01

A commonly used aeration device at present has the disadvantages of low mass transfer rate because the generated bubbles are several millimeters in diameter which are much bigger than microbubbles. Therefore, the effect of a microbubble on gas-liquid mass transfer and wastewater treatment process was investigated. To evaluate the effect of each bubble type, the volumetric mass transfer coefficients for microbubbles and conventional bubbles were determined. The volumetric mass transfer coefficient was 0.02905 s(-1) and 0.02191 s(-1) at a gas flow rate of 0.67 L min(-1) in tap water for microbubbles and conventional bubbles, respectively. The degradation rate of simulated municipal wastewater was also investigated, using aerobic activated sludge and ozone. Compared with the conventional bubble generator, the chemical oxygen demand (COD) removal rate was 2.04, 5.9, 3.26 times higher than those of the conventional bubble contactor at the same initial COD concentration of COD 200 mg L(-1), 400 mg L(-1), and 600 mg L(-1), while aerobic activated sludge was used. For the ozonation process, the rate of COD removal using microbubble generator was 2.38, 2.51, 2.89 times of those of the conventional bubble generator. Based on the results, the effect of initial COD concentration on the specific COD degradation rate were discussed in different systems. Thus, the results revealed that microbubbles could enhance mass transfer in wastewater treatment and be an effective method to improve the degradation of wastewater.

Online solid-phase extraction with high-performance liquid chromatography and mass spectrometry for the determination of five tannins in traditional Chinese medicine injections.

PubMed

Sun, Meng; Lin, Yuanyuan; Zhang, Jie; Zheng, Shaohua; Wang, Sicen

2016-03-01

A rapid analytical method based on online solid-phase extraction with high-performance liquid chromatography and mass spectrometry has been established and applied to the determination of tannin compounds that may cause adverse effects in traditional Chinese medicine injections. Different solid-phase extraction sorbents have been compared and the elution buffer was optimized. The performance of the method was verified by evaluation of recovery (≥40%), repeatability (RSD ≤ 6%), linearity (r(2) ≥ 0.993), and limit of quantification (≤0.35 μg/mL). Five tannin compounds, gallic acid, cianidanol, gallocatechin gallate, ellagic acid, and penta-O-galloylglucose, were identified with concentrations ranging from 3.1-37.4 μg/mL in the analyzed traditional Chinese medicine injections. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Rejuvenation of Spent Media via Supported Emulsion Liquid Membranes

NASA Technical Reports Server (NTRS)

Wiencek, John M.

2002-01-01

The overall goal of this project is to maximize the reuseability of spent fermentation media. Supported emulsion liquid membrane separation, a highly efficient extraction technique, is used to remove inhibitory byproducts during fermentation; thus, improving the yield while reducing the need for fresh water. The key objectives of this study are: Develop an emulsion liquid membrane system targeting low molecular weight organic acids which has minimal toxicity on a variety of microbial systems; Conduct mass transfer studies to allow proper modeling and design of a supported emulsion liquid membrane system; Investigate the effect of gravity on emulsion coalescence within the membrane unit; Access the effect of water re-use on fermentation yields in a model microbial system; Develop a perfusion-type fermentor utilizing a supported emulsion liquid membrane system to control inhibitory fermentation byproducts; Work for the coming year will focus on the determination of toxicity of various solvents, selection of the emulsifying agents, as well as characterizing the mass transfer of hollow-fiber contactors.

Heat and mass exchanger

DOEpatents

Lowenstein, Andrew; Sibilia, Marc J.; Miller, Jeffrey A.; Tonon, Thomas

2007-09-18

A mass and heat exchanger includes at least one first substrate with a surface for supporting a continuous flow of a liquid thereon that either absorbs, desorbs, evaporates or condenses one or more gaseous species from or to a surrounding gas; and at least one second substrate operatively associated with the first substrate. The second substrate includes a surface for supporting the continuous flow of the liquid thereon and is adapted to carry a heat exchange fluid therethrough, wherein heat transfer occurs between the liquid and the heat exchange fluid.

Heat and mass exchanger

DOEpatents

Lowenstein, Andrew [Princeton, NJ; Sibilia, Marc J [Princeton, NJ; Miller, Jeffrey A [Hopewell, NJ; Tonon, Thomas [Princeton, NJ

2011-06-28

A mass and heat exchanger includes at least one first substrate with a surface for supporting a continuous flow of a liquid thereon that either absorbs, desorbs, evaporates or condenses one or more gaseous species from or to a surrounding gas; and at least one second substrate operatively associated with the first substrate. The second substrate includes a surface for supporting the continuous flow of the liquid thereon and is adapted to carry a heat exchange fluid therethrough, wherein heat transfer occurs between the liquid and the heat exchange fluid.

Combined liquid chromatography-mass spectrometry for trace analysis of pharmaceuticals

NASA Astrophysics Data System (ADS)

Schmidt, Lothar; Danigel, Harald; Jungclas, Hartmut

1982-07-01

A 252Cf-plasma desorption mass spectrometer (PDMS) for the analysis of thin layers from nonvolatile organic samples has been set up to be combined with a liquid chromatograph. A novel interface performs the direct inlet of the liquid sample through a capillary into the vacuum system of the spectrometer. Samples of drugs are periodically collected, transferred to the ion source and analysed using a rotating disk. This on-line sample preparation has been tested for three antiarrhythmic drugs using various solvents and mixtures.

An improved heat transfer configuration for a solid-core nuclear thermal rocket engine

NASA Technical Reports Server (NTRS)

Clark, John S.; Walton, James T.; Mcguire, Melissa L.

1992-01-01

Interrupted flow, impingement cooling, and axial power distribution are employed to enhance the heat-transfer configuration of a solid-core nuclear thermal rocket engine. Impingement cooling is introduced to increase the local heat-transfer coefficients between the reactor material and the coolants. Increased fuel loading is used at the inlet end of the reactor to enhance heat-transfer capability where the temperature differences are the greatest. A thermal-hydraulics computer program for an unfueled NERVA reactor core is employed to analyze the proposed configuration with attention given to uniform fuel loading, number of channels through the impingement wafers, fuel-element length, mass-flow rate, and wafer gap. The impingement wafer concept (IWC) is shown to have heat-transfer characteristics that are better than those of the NERVA-derived reactor at 2500 K. The IWC concept is argued to be an effective heat-transfer configuration for solid-core nuclear thermal rocket engines.

Numerical Modeling of Self-Pressurization and Pressure Control by Thermodynamic Vent System in a Cryogenic Tank

NASA Technical Reports Server (NTRS)

Majumdar, Alok; Valenzuela, Juan; LeClair, Andre; Moder, Jeff

2015-01-01

This paper presents a numerical model of a system-level test bed - the multipurpose hydrogen test bed (MHTB) using Generalized Fluid System Simulation Program (GFSSP). MHTB is representative in size and shape of a fully integrated space transportation vehicle liquid hydrogen (LH2) propellant tank and was tested at Marshall Space Flight Center (MSFC) to generate data for cryogenic storage. GFSSP is a finite volume based network flow analysis software developed at MSFC and used for thermo-fluid analysis of propulsion systems. GFSSP has been used to model the self-pressurization and ullage pressure control by Thermodynamic Vent System (TVS). A TVS typically includes a Joule-Thompson (J-T) expansion device, a two-phase heat exchanger, and a mixing pump and spray to extract thermal energy from the tank without significant loss of liquid propellant. Two GFSSP models (Self-Pressurization & TVS) were separately developed and tested and then integrated to simulate the entire system. Self-Pressurization model consists of multiple ullage nodes, propellant node and solid nodes; it computes the heat transfer through Multi-Layer Insulation blankets and calculates heat and mass transfer between ullage and liquid propellant and ullage and tank wall. TVS model calculates the flow through J-T valve, heat exchanger and spray and vent systems. Two models are integrated by exchanging data through User Subroutines of both models. The integrated models results have been compared with MHTB test data of 50% fill level. Satisfactory comparison was observed between test and numerical predictions.

Gas-liquid mass transfer and flow phenomena in the Peirce-Smith converter: a water model study

NASA Astrophysics Data System (ADS)

Zhao, Xing; Zhao, Hong-liang; Zhang, Li-feng; Yang, Li-qiang

2018-01-01

A water model with a geometric similarity ratio of 1:5 was developed to investigate the gas-liquid mass transfer and flow characteristics in a Peirce-Smith converter. A gas mixture of CO2 and Ar was injected into a NaOH solution bath. The flow field, volumetric mass transfer coefficient per unit volume ( Ak/V; where A is the contact area between phases, V is the volume, and k is the mass transfer coefficient), and gas utilization ratio ( η) were then measured at different gas flow rates and blow angles. The results showed that the flow field could be divided into five regions, i.e., injection, strong loop, weak loop, splashing, and dead zone. Whereas the Ak/V of the bath increased and then decreased with increasing gas flow rate, and η steadily increased. When the converter was rotated clockwise, both Ak/V and η increased. However, the flow condition deteriorated when the gas flow rate and blow angle were drastically increased. Therefore, these parameters must be controlled to optimal conditions. In the proposed model, the optimal gas flow rate and blow angle were 7.5 m3·h-1 and 10°, respectively.

Modeling of gas-liquid mass transfer in a stirred tank bioreactor agitated by a Rushton turbine or a new pitched blade impeller.

PubMed

Gelves, Ricardo; Dietrich, A; Takors, Ralf

2014-03-01

A combined computational fluid dynamics (CFD) and population balance model (PBM) approach has been applied to simulate hydrodynamics and mass transfer in a 0.18 m(3) gas-liquid stirred bioreactor agitated by (1) a Rushton turbine, and (2) a new pitched blade geometry with rotating cartridges. The operating conditions chosen were motivated by typical settings used for culturing mammalian cells. The effects of turbulence, rotating flow, bubbles breakage and coalescence were simulated using the k-ε, multiple reference frame (MRF), Sliding mesh (SM) and PBM approaches, respectively. Considering the new pitched blade geometry with rotating aeration microspargers, [Formula: see text] mass transfer was estimated to be 34 times higher than the conventional Rushton turbine set-up. Notably, the impeller power consumption was modeled to be about 50 % lower. Independent [Formula: see text] measurements applying the same operational conditions confirmed this finding. Motivated by these simulated and experimental results, the new aeration and stirring device is qualified as a very promising tool especially useful for cell culture applications which are characterized by the challenging problem of achieving relatively high mass transfer conditions while inserting only low stirrer energy.

Molecular dynamic approach to the study of the intense heat and mass transfer processes on the vapor-liquid interface

NASA Astrophysics Data System (ADS)

Levashov, V. Yu; Kamenov, P. K.

2017-10-01

The paper is devoted to research of the heat and mass transfer processes on the vapor-liquid interface. These processes can be realized for example at metal tempering, accidents at nuclear power stations, followed by the release of the corium into the heat carrier, getting hot magma into the water during volcanic eruptions and other. In all these examples the vapor film can arise on the heated body surface. In this paper the vapor film formation process will be considered with help of molecular dynamics simulation methods. The main attention during this process modeling will be focused on the subject of the fluid and vapor interactions with the heater surface. Another direction of this work is to study of the processes inside the droplet that may take place as result of impact of the high-power laser radiation. Such impact can lead to intensive evaporation and explosive destruction of the droplet. At that the duration of heat and mass transfer processes in droplet substance is tens of femtoseconds. Thus, the methods of molecular dynamics simulation can give the possibilities describe the heat and mass transfer processes in the droplet and the vapor phase formation.

Microfluidic Liquid-Liquid Contactors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mcculloch, Quinn

2017-07-25

This report describes progress made on the microfluidic contactor. A model was developed to predict its failure, a surrogate chemical system was selected to demonstrate mass transfer, and an all-optical system has been invented and implemented to monitor carryover and flowrates.

Novel Liquid Sorbent C02 Removal System for Microgravity Applications

NASA Technical Reports Server (NTRS)

Rogers, Tanya; Westover, Shayne; Graf, John

2017-01-01

Removing Carbon Dioxide (CO2) from a spacecraft environment for deep space exploration requires a robust system that is low in weight, power, and volume. Current state-of-the-art microgravity compatible CO2 removal systems, such as the carbon dioxide removal assembly (CDRA), utilize solid sorbents that demand high power usage due to high desorption temperatures and a large volume to accommodate for their comparatively low capacity for CO2. Additionally, solid sorbent systems contain several mechanical components that significantly reduce reliability and contribute to a large overall mass. A liquid sorbent based system has been evaluated as an alternative is proposed to consume 65% less power, weight, and volume than solid based CO2 scrubbers. This paper presents the design of a liquid sorbent CO2 removal system for microgravity applications.

Transient Numerical Modeling of Catalytic Channels

NASA Technical Reports Server (NTRS)

Struk, Peter M.; Dietrich, Daniel L.; Miller, Fletcher J.; T'ien, James S.

2007-01-01

This paper presents a transient model of catalytic combustion suitable for isolated channels and monolith reactors. The model is a lumped two-phase (gas and solid) model where the gas phase is quasi-steady relative to the transient solid. Axial diffusion is neglected in the gas phase; lateral diffusion, however, is accounted for using transfer coefficients. The solid phase includes axial heat conduction and external heat loss due to convection and radiation. The combustion process utilizes detailed gas and surface reaction models. The gas-phase model becomes a system of stiff ordinary differential equations while the solid phase reduces, after discretization, into a system of stiff ordinary differential-algebraic equations. The time evolution of the system came from alternating integrations of the quasi-steady gas and transient solid. This work outlines the numerical model and presents some sensitivity studies on important parameters including internal transfer coefficients, catalytic surface site density, and external heat-loss (if applicable). The model is compared to two experiments using CO fuel: (1) steady-state conversion through an isothermal platinum (Pt) tube and (2) transient propagation of a catalytic reaction inside a small Pt tube. The model requires internal mass-transfer resistance to match the experiments at lower residence times. Under mass-transport limited conditions, the model reasonably predicted exit conversion using global mass-transfer coefficients. Near light-off, the model results did not match the experiment precisely even after adjustment of mass-transfer coefficients. Agreement improved for the first case after adjusting the surface kinetics such that the net rate of CO adsorption increased compared to O2. The CO / O2 surface mechanism came from a sub-set of reactions in a popular CH4 / O2 mechanism. For the second case, predictions improved for lean conditions with increased external heat loss or adjustment of the kinetics as in the first case. Finally, the results show that different initial surface-species distribution leads to different steady-states under certain conditions. These results demonstrate the utility of a lumped two-phase model of a transient catalytic combustor with detailed chemistry.

Finite element procedures for coupled linear analysis of heat transfer, fluid and solid mechanics

NASA Technical Reports Server (NTRS)

Sutjahjo, Edhi; Chamis, Christos C.

1993-01-01

Coupled finite element formulations for fluid mechanics, heat transfer, and solid mechanics are derived from the conservation laws for energy, mass, and momentum. To model the physics of interactions among the participating disciplines, the linearized equations are coupled by combining domain and boundary coupling procedures. Iterative numerical solution strategy is presented to solve the equations, with the partitioning of temporal discretization implemented.

Desorption in Mass Spectrometry.

PubMed

Usmanov, Dilshadbek Tursunbayevich; Ninomiya, Satoshi; Chen, Lee Chuin; Saha, Subhrakanti; Mandal, Mridul Kanti; Sakai, Yuji; Takaishi, Rio; Habib, Ahsan; Hiraoka, Kenzo; Yoshimura, Kentaro; Takeda, Sen; Wada, Hiroshi; Nonami, Hiroshi

2017-01-01

In mass spectrometry, analytes must be released in the gas phase. There are two representative methods for the gasification of the condensed samples, i.e. , ablation and desorption. While ablation is based on the explosion induced by the energy accumulated in the condensed matrix, desorption is a single molecular process taking place on the surface. In this paper, desorption methods for mass spectrometry developed in our laboratory: flash heating/rapid cooling, Leidenfrost phenomenon-assisted thermal desorption (LPTD), solid/solid friction, liquid/solid friction, electrospray droplet impact (EDI) ionization/desorption, and probe electrospray ionization (PESI), will be described. All the methods are concerned with the surface and interface phenomena. The concept of how to desorb less-volatility compounds from the surface will be discussed.

TANK 26 EVAPORATOR FEED PUMP TRANSFER ANALYSIS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tamburello, D; Si Lee, S; Richard Dimenna, R

2008-09-30

The transfer of liquid salt solution from Tank 26 to an evaporator is to be accomplished by activating the evaporator feed pump, located approximately 72 inches above the sludge layer, while simultaneously turning on the downcomer. Previously, activation of the evaporator feed pump was an isolated event without any other components running at the same time. An analysis of the dissolved solution transfer has been performed using computational fluid dynamics methods to determine the amount of entrained sludge solids pumped out of the tank to the evaporator with the downcomer turned on. The analysis results showed that, for the maximummore » and minimum supernate levels in Tank 26 (252.5 and 72 inches above the sludge layer, respectively), the evaporator feed pump will entrain between 0.05 and 0.1 wt% sludge solids weight fraction into the eductor, respectively. Lower tank liquid levels, with respect to the sludge layer, result in higher amounts of sludge entrainment due to the increased velocity of the plunging jets from the downcomer and evaporator feed pump bypass as well as decreased dissipation depth.« less

Investigation the evaporation-condensation problem by means of the joint numerical solution of the Boltzmann kinetic equation and interface modelling

NASA Astrophysics Data System (ADS)

Shiskova, I. N.; Kryukov, A. P.; Levashov, V. Yu

2017-11-01

The paper is devoted to research of the heat and mass transfer processes in liquid and vapor phase on the basis of the uniform approach assuming the through description of liquid, interface and vapor. Multiparticles interactions in liquid will be taken into account. The problem is studied when temperature in the depth of liquid differs from temperature in the vapor region. In this case there are both mass flux and heat flux. The study of influence of the correlations resulting from interactions of molecules set in thin near-surface liquid layers and an interface on intensity of evaporation is made. As a result of calculations the equilibrium line of the liquid-vapor saturation is obtained, which corresponds good enough with experimental data. Distributions of density, temperature, pressure, heat and mass fluxes, both in a liquid and in vapor are also presented.

Performance analysis of an air drier for a liquid dehumidifier solar air conditioning system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Queiroz, A.G.; Orlando, A.F.; Saboya, F.E.M.

1988-05-01

A model was developed for calculating the operating conditions of a non-adiabatic liquid dehumidifier used in solar air conditioning systems. In the experimental facility used for obtaining the data, air and triethylene glycol circulate countercurrently outside staggered copper tubes which are the filling of an absorption tower. Water flows inside the copper tubes, thus cooling the whole system and increasing the mass transfer potential for drying air. The methodology for calculating the mass transfer coefficient is based on the Merkel integral approach, taking into account the lowering of the water vapor pressure in equilibrium with the water glycol solution.

A mass diffusion-based interpretation of the effect of total solids content on solid-state anaerobic digestion of cellulosic biomass.

PubMed

Xu, Fuqing; Wang, Zhi-Wu; Tang, Li; Li, Yebo

2014-09-01

In solid-state anaerobic digestion (SS-AD) of cellulosic biomass, the volumetric methane production rate has often been found to increase with the increase in total solids (TS) content until a threshold is reached, and then to decrease. This phenomenon cannot be explained by conventional understanding derived from liquid anaerobic digestion. This study proposed that the high TS content-caused mass diffusion limitation may be responsible for the observed methane production deterioration. Based on this hypothesis, a new SS-AD model was developed by taking into account the mass diffusion limitation and hydrolysis inhibition. The good agreement between model simulation and the experimental as well as literature data verified that the observed reduction in volumetric methane production rate could be ascribed to hydrolysis inhibition as a result of the mass diffusion limitation in SS-AD. Copyright © 2014 Elsevier Ltd. All rights reserved.

Modeling pH-zone refining countercurrent chromatography: a dynamic approach.

PubMed

Kotland, Alexis; Chollet, Sébastien; Autret, Jean-Marie; Diard, Catherine; Marchal, Luc; Renault, Jean-Hugues

2015-04-24

A model based on mass transfer resistances and acid-base equilibriums at the liquid-liquid interface was developed for the pH-zone refining mode when it is used in countercurrent chromatography (CCC). The binary separation of catharanthine and vindoline, two alkaloids used as starting material for the semi-synthesis of chemotherapy drugs, was chosen for the model validation. Toluene/CH3CN/water (4/1/5, v/v/v) was selected as biphasic solvent system. First, hydrodynamics and mass transfer were studied by using chemical tracers. Trypan blue only present in the aqueous phase allowed the determination of the parameters τextra and Pe for hydrodynamic characterization whereas acetone, which partitioned between the two phases, allowed the determination of the transfer parameter k0a. It was shown that mass transfer was improved by increasing both flow rate and rotational speed, which is consistent with the observed mobile phase dispersion. Then, the different transfer parameters of the model (i.e. the local transfer coefficient for the different species involved in the process) were determined by fitting experimental concentration profiles. The model accurately predicted both equilibrium and dynamics factors (i.e. local mass transfer coefficients and acid-base equilibrium constant) variation with the CCC operating conditions (cell number, flow rate, rotational speed and thus stationary phase retention). The initial hypotheses (the acid-base reactions occurs instantaneously at the interface and the process is mainly governed by mass transfer) are thus validated. Finally, the model was used as a tool for catharanthine and vindoline separation prediction in the whole experimental domain that corresponded to a flow rate between 20 and 60 mL/min and rotational speeds from 900 and 2100 rotation per minutes. Copyright © 2015 Elsevier B.V. All rights reserved.

Manifold to uniformly distribute a solid-liquid slurry

DOEpatents

Kern, Kenneth C.

1983-01-01

This invention features a manifold that divides a stream of coal particles and liquid into several smaller streams maintaining equal or nearly equal mass compositions. The manifold consists of a horizontal, variable area header having sharp-edged, right-angled take-offs which are oriented on the bottom of the header.

Effectiveness of Liquid-Liquid Extraction, Solid Phase Extraction, and Headspace Technique for Determination of Some Volatile Water-Soluble Compounds of Rose Aromatic Water

PubMed Central

2017-01-01

Steam distillation is used to isolate scent of rose flowers. Rose aromatic water is commonly used in European cuisine and aromatherapy besides its use in cosmetic industry for its lovely scent. In this study, three different sampling techniques, liquid-liquid extraction (LLE), headspace technique (HS), and solid phase extraction (SPE), were compared for the analysis of volatile water-soluble compounds in commercial rose aromatic water. Some volatile water-soluble compounds of rose aromatic water were also analyzed by gas chromatography mass spectrometry (GCMS). In any case, it was concluded that one of the solid phase extraction methods led to higher recoveries for 2-phenylethyl alcohol (PEA) in the rose aromatic water than the liquid-liquid extraction and headspace technique. Liquid-liquid extraction method provided higher recovery ratios for citronellol, nerol, and geraniol than others. Ideal linear correlation coefficient values were observed by GCMS for quantitative analysis of volatile compounds (r2 ≥ 0.999). Optimized methods showed acceptable repeatability (RSDs < 5%) and excellent recovery (>95%). For compounds such as α-pinene, linalool, β-caryophyllene, α-humulene, methyl eugenol, and eugenol, the best recovery values were obtained with LLE and SPE. PMID:28791049

Simultaneous determination of three classes of antibiotics in the suspended solids of swine wastewater by ultrasonic extraction, solid-phase extraction and liquid chromatography-mass spectrometry.

PubMed

Pan, Xun; Qiang, Zhimin; Ben, Weiwei; Chen, Meixue

2011-01-01

This work describes a systematic approach to the development of a method for simultaneous determination of three classes of veterinary antibiotics in the suspended solids (SS) of swine wastewater, including five sulfonamides, three tetracyclines and one macrolide (tiamulin). The entire procedures for sample pretreatment, ultrasonic extraction (USE), solid-phase extraction (SPE), and liquid chromatography-mass spectrometry (LC-MS) quantification were examined and optimized. The recovery efficiencies were found to be 76%-104% for sulfonamides, 81%-112% for tetracyclines, and 51%-64% for tiamulin at three spiking levels. The intra-day and inter-day precisions, as expressed by the relative standard deviation (RSD), were below 17%. The method detection limits (MDLs) were between 0.14 and 7.14 microg/kg, depending on a specific antibiotic studied. The developed method was applied to field samples collected from three concentrated swine feeding plants located in Beijing, Shanghai and Shandong province of China. All the investigated antibiotics were detected in both SS and liquid phase of swine wastewater, with partition coefficients (logK(d)) ranging from 0.49 to 2.30. This study demonstrates that the SS can not be ignored when determining the concentrations of antibiotics in swine wastewater.

Determination of quaternary ammonium compounds in seawater samples by solid-phase extraction and liquid chromatography-mass spectrometry.

PubMed

Bassarab, P; Williams, D; Dean, J R; Ludkin, E; Perry, J J

2011-02-04

A method for the simultaneous determination of two biocidal quaternary ammonium compounds; didecyldimethylammonium chloride (didecyldimethyl quat) and dodecylbenzyldimethylammonium chloride (benzyl quat), in seawater by solid phase extraction (SPE) followed by liquid chromatography-mass spectrometry (LC-MS) was developed. The optimised procedure utilised off-line extraction of the analytes from seawater using polymeric (Strata-X) SPE cartridges. Recoveries ranged from 80 to 105%, with detection limits at the low parts-per-trillion (ng/l) level for both analytes. To demonstrate sensitivity, environmental concentrations were measured at three different locations along the North East coast of England with measured values in the range 120-270ng/l. Copyright © 2010 Elsevier B.V. All rights reserved.

Mass transfer apparatus and method for separation of gases

DOEpatents

Blount, Gerald C.

2015-10-13

A process and apparatus for separating components of a source gas is provided in which more soluble components of the source gas are dissolved in an aqueous solvent at high pressure. The system can utilize hydrostatic pressure to increase solubility of the components of the source gas. The apparatus includes gas recycle throughout multiple mass transfer stages to improve mass transfer of the targeted components from the liquid to gas phase. Separated components can be recovered for use in a value added application or can be processed for long-term storage, for instance in an underwater reservoir.

Mass transfer apparatus and method for separation of gases

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blount, Gerald C.; Gorensek, Maximilian Boris; Hamm, Luther L.

A process and apparatus for separating components of a source gas is provided in which more soluble components of the source gas are dissolved in an aqueous solvent at high pressure. The system can utilize hydrostatic pressure to increase solubility of the components of the source gas. The apparatus includes gas recycle throughout multiple mass transfer stages to improve mass transfer of the targeted components from the liquid to gas phase. Separated components can be recovered for use in a value added application or can be processed for long-term storage, for instance in an underwater reservoir.

Estimation of interfacial area in a packed cross-flow cascade with distillation of ethanol-water, methanol-water, and hexane-heptane

DOE Office of Scientific and Technical Information (OSTI.GOV)

Velaga, A.

1986-01-01

Packed cross-flow internals consisting of four and ten stages including the samplers for liquid and vapor were fabricated to fit into the existing distillation column. Experiments were conducted using methanol-water, ethanol-water and hexane-heptane binary mixtures. The experimental data were collected for compositions of inlet and exist streams of cross-flow stages. The overall gas phase height transfer units (H/sub og/) were estimated using the experimental data. H/sub og/ values were compared to those of counter current conditions. The individual mass transfer coefficients in the liquid and vapor phases were estimated using the collected experimental data for degree of separation, flow ratesmore » and physical properties of the binary system used. The physical properties were estimated at an average temperature of the specific cross-flow stage. The mass transfer coefficients were evaluated using three different correlations proposed by Shulman. Onda and Hayashi respectively. The interfacial areas were estimated using the evaluated mass transfer coefficients and the experimental data at each stage of the column for different runs and compared.« less

Nano scale dynamics of bubble nucleation in confined liquid subjected to rapid cooling: Effect of solid-liquid interfacial wettability

NASA Astrophysics Data System (ADS)

Hasan, Mohammad Nasim; Rabbi, Kazi Fazle; Mukut, K. M.; Tamim, Saiful Islam; Faisal, A. H. M.

2017-06-01

This study focuses on the occurrence of bubble nucleation in a liquid confined in a nano scale confinement and subjected to rapid cooling at one of its wall. Due to the very small size scale of the present problem, we adopt the molecular dynamics (MD) approach. The liquid (Argon) is confined within two solid (Platinum) walls. The temperature of the upper wall of the confinement is maintained at 90 K while the lower wall is being cooled rapidly to 50 K from initial equilibrium temperature of 90 K within 0.1 ns. This results in the nucleation and formation of nanobubbles in the liquid. The pattern of bubble nucleation has been studied for three different conditions of solid-liquid interfacial wettability such as hydrophilic, hydrophobic and neutral. Behavior of bubble nucleation is significantly different in the three case of solid-liquid interfacial wettability. In case of the hydrophobic confinement (weakly adsorbing), the liquid cannot achieve deeper metastability; vapor layers appear immediately on the walls. In case of the neutral confinement (moderately adsorbing), bubble nucleation is promoted by the walls where the nucleation is heterogeneous. In case of the hydrophilic walls (strongly adsorbing) bubbles are developed inside the liquid; that is the nucleation process is homogeneous. The variation in bubble nucleation under different conditions of surface wettability has been studied by the analysis of number density distribution, spatial temperature distribution, spatial number density distribution and heat flux through the upper and lower walls of the confinement. The present study indicates that the variation of heat transfer efficiency due to different surface wettability has significant effect on the size, shape and location of bubble nucleation in case rapid cooling of liquid in nano confinement.

Unsteady heat transfer performance of heat pipe with axially swallow-tailed microgrooves

NASA Astrophysics Data System (ADS)

Zhang, R. P.

2017-04-01

A mathematical model is developed for predicting the transient heat transfer and fluid flow of heat pipe with axially swallow-tailed microgrooves. The effects of liquid convective heat transfer in the microgrooves, liquid-vapor interfacial phase-change heat transfer and liquid-vapor interfacial shear stress are accounted for in the present model. The coupled non-linear control equations are solved numerically. Mass flow rate at the interface is obtained from the application of kinetic theory. Time variation of wall temperature is studied from the initial startup to steady state. The numerical results are verified by experiments. Time constants for startup and shutdown operation are defined to determine how fast a heat pipe responds to an applied input heat flux, which slightly decreases with increasing heat load.

Solid-phase extraction in combination with dispersive liquid-liquid microextraction and ultra-high performance liquid chromatography-tandem mass spectrometry analysis: the ultra-trace determination of 10 antibiotics in water samples.

PubMed

Liang, Ning; Huang, Peiting; Hou, Xiaohong; Li, Zhen; Tao, Lei; Zhao, Longshan

2016-02-01

A novel method, solid-phase extraction combined with dispersive liquid-liquid microextraction (SPE-DLLME), was developed for ultra-preconcentration of 10 antibiotics in different environmental water samples prior to ultra-high performance liquid chromatography-tandem mass spectrometry detection. The optimized results were obtained as follows: after being adjusted to pH 4.0, the water sample was firstly passed through PEP-2 column at 10 mL min(-1), and then methanol was used to elute the target analytes for the following steps. Dichloromethane was selected as extraction solvent, and methanol/acetonitrile (1:1, v/v) as dispersive solvent. Under optimal conditions, the calibration curves were linear in the range of 1-1000 ng mL(-1) (sulfamethoxazole, cefuroxime axetil), 5-1000 ng mL(-1) (tinidazole), 10-1000 ng mL(-1) (chloramphenicol), 2-1000 ng mL(-1) (levofloxacin oxytetracycline, doxycycline, tetracycline, and ciprofloxacin) and 1-400 ng mL(-1) (sulfadiazine) with a good precision. The LOD and LOQ of the method were at very low levels, below 1.67 and 5.57 ng mL(-1), respectively. The relative recoveries of the target analytes were in the range from 64.16% to 99.80% with relative standard deviations between 0.7 and 8.4%. The matrix effect of this method showed a great decrease compared with solid-phase extraction and a significant value of enrichment factor (EF) compared with dispersive liquid-liquid microextraction. The developed method was successfully applied to the extraction and analysis of antibiotics in different water samples with satisfactory results.

Thermal transport study across interface “nanostructured solid surface / fluid” by photoacoustic technique

NASA Astrophysics Data System (ADS)

Voitenko, K.; Isaiev, M.; Pastushenko, A.; Andrusenko, D.; Kuzmich, A.; Lysenko, V.; Burbelo, R.

2017-01-01

In the paper the experimental study of heat transport across the interface “porous silicon/liquid” by photoacoustic technique is reported. Two cases with and without liquid covering of porous silicon surface were considered. Thermal perturbations were excited at the surface of porous silicon as a result of absorption of the light with modulated intensity. The resulting thermal-elastic stresses arising in the system were registered with piezoelectric transducer. The amplitude-frequency dependencies of the voltage on the piezoelectric electrodes were measured. The presence of the liquid film leads to decreasing of the amplitude of photoacoustic signal as a result of the thermal energy evacuation from the porous silicon into the liquid. The experimental dependencies were fitted with the results of simulation that takes into account heat fluxes separation at the porous silicon/liquid interface. With the presented method one can precisely measure heat fluxes transferred from the solid into contacting fluid. Moreover, the presented approach can be easily adopted for the thermal conductivity study of the different nanofluids as well as thermal resistance at the interface nanostructured solid/fluid.

The Delta launch vehicle Model 2914 series

NASA Technical Reports Server (NTRS)

Gunn, C. R.

1973-01-01

Description of a new, medium-class Delta launch-vehicle configuration, the three-stage Model 2914. The first stage of this vehicle is composed of a liquid-propellant core which is thrust-augmented with up to nine strap-on solid-propellant motors. The second stage, recently uprated with a strap-down inertial guidance system, is now being modified to adapt the liquid-propellant descent engine from the Apollo Lunar Excursion Module. The third stage is a spin-stabilized solid-propellant motor. The Model 2914 is capable of injecting 2040 kg into low earth orbit, 705 kg into geosynchronous transfer orbit, or 455 kg into an escape trajectory.

Modeling the Capillary Pressure for the Migration of the Liquid Phase in Granular Solid-Liquid-Vapor Systems: Application to the Control of the Composition Profile in W-Cu FGM Materials

NASA Astrophysics Data System (ADS)

Missiaen, Jean-Michel; Raharijaona, Jean-Joël; Delannay, Francis

2016-11-01

A model is developed to compute the capillary pressure for the migration of the liquid phase out or into a uniform solid-liquid-vapor system. The capillary pressure is defined as the reduction of the overall interface energy per volume increment of the transferred fluid phase. The model takes into account the particle size of the solid particle aggregate, the packing configuration (coordination number, porosity), the volume fractions of the different phases, and the values of the interface energies in the system. The model is used for analyzing the stability of the composition profile during processing of W-Cu functionally graded materials combining a composition gradient with a particle size gradient. The migration pressure is computed with the model in two stages: (1) just after the melting of copper, i.e., when sintering and shape accommodation of the W particle aggregate can still be neglected and (2) at high temperature, when the system is close to full density with equilibrium particle shape. The model predicts well the different stages of liquid-phase migration observed experimentally.

Indirect evaporative cooler using membrane-contained, liquid desiccant for dehumidification

DOEpatents

Kozubal, Eric Joseph

2016-12-13

An indirect evaporative cooler for cooling inlet supply air from a first temperature to a second, lower temperature using a stream of liquid coolant and a stream of exhaust or purge air. The cooler includes a first flow channel for inlet supply air and a second flow channel adjacent the first for exhaust air. The first and second flow channels are defined in part by sheets of a membrane permeable to water vapor such that mass is transferred as a vapor through the membrane from the inlet supply air to a contained liquid desiccant for dehumidification and also to the exhaust air as heat is transferred from the inlet supply air to the liquid coolant. A separation wall divides the liquid desiccant and the coolant but allows heat to be transferred from the supply air to the coolant which releases water vapor to the counter or cross flowing exhaust air.

Indirect evaporative cooler using membrane-contained, liquid desiccant for dehumidification

DOEpatents

Kozubal, Eric Joseph; Slayzak, Steven Joseph

2014-07-08

An indirect evaporative cooler for cooling inlet supply air from a first temperature to a second, lower temperature using a stream of liquid coolant and a stream of exhaust or purge air. The cooler includes a first flow channel for inlet supply air and a second flow channel adjacent the first for exhaust air. The first and second flow channels are defined in part by sheets of a membrane permeable to water vapor such that mass is transferred as a vapor through the membrane from the inlet supply air to a contained liquid desiccant for dehumidification and also to the exhaust air as heat is transferred from the inlet supply air to the liquid coolant. A separation wall divides the liquid desiccant and the coolant but allows heat to be transferred from the supply air to the coolant which releases water vapor to the counter or cross flowing exhaust air.

Solubility of Structurally Complicated Materials: 3. Hair

PubMed Central

Horvath, Ari L.

2009-01-01

Hair is composed of proteins, lipids, water, and small amounts of trace elements. All proteins in animal and human bodies are built from permutations of amino acid molecules in a polypeptide string. The polypeptide chains of protein keratin are organized into filaments in hair cells. Hair is one of the most difficult proteins to digest or solubilize. Among the most common dissolving procedures for hair are acidic, alkaline, and enzymatic hydrolysis. For the analysis of hair, the solid samples are transferred by solubilization via digestion into a liquid phase. Small molecular solvents and molecules with hydrophobic groups appear to have higher affinity for hair. A good solvent attacks the disulfide bonds between cystine molecules and hydrates the hair shaft. Consequently, the hair becomes a jelly-like mass. PMID:19412554

Modeling Manganese Silicate Inclusion Composition Changes during Ladle Treatment Using FactSage Macros

NASA Astrophysics Data System (ADS)

Piva, Stephano P. T.; Kumar, Deepoo; Pistorius, P. Chris

2017-02-01

This work investigated the use of FactSage macros to simulate steel-slag and steel-inclusion reaction kinetics in silicon-manganese killed steels, and predict oxide inclusion composition changes during ladle treatment. These changes were assessed experimentally using an induction furnace to simulate deoxidation and slag addition. The average steel mass transfer coefficient for the experimental setup was calculated from the analyzed aluminum pick-up by steel. Average oxide inclusion composition was measured using scanning electron microscopy and energy-dispersive X-ray spectroscopy. Confocal laser scanning microscopy was used to assess the physical state (solid or liquid) of oxide inclusions in selected samples. The changes in the chemical compositions of the oxide inclusions and the steel agreed with the FactSage macro simulations.

Quantitative Analysis of Tetramethylenedisulfotetramine ("Tetramine") Spiked into Beverages by Liquid Chromatography Tandem Mass Spectrometry with Validation by Gas Chromatography Mass Spectrometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Owens, J; Hok, S; Alcaraz, A

Tetramethylenedisulfotetramine, commonly known as tetramine, is a highly neurotoxic rodenticide (human oral LD{sub 50} = 0.1 mg/kg) used in hundreds of deliberate food poisoning events in China. Here we describe a method for quantitation of tetramine spiked into beverages, including milk, juice, tea, cola, and water and cleaned up by C8 solid phase extraction and liquid-liquid extraction. Quantitation by high performance liquid chromatography tandem mass spectrometry (LC/MS/MS) was based upon fragmentation of m/z 347 to m/z 268. The method was validated by gas chromatography mass spectrometry (GC/MS) operated in SIM mode for ions m/z 212, 240, and 360. The limitmore » of quantitation was 0.10 {micro}g/mL by LC/MS/MS versus 0.15 {micro}g/mL for GC/MS. Fortifications of the beverages at 2.5 {micro}g/mL and 0.25 {micro}g/mL were recovered ranging from 73-128% by liquid-liquid extraction for GC/MS analysis, 13-96% by SPE and 10-101% by liquid-liquid extraction for LC/MS/MS analysis.« less

Numerical modeling and analytical modeling of cryogenic carbon capture in a de-sublimating heat exchanger

NASA Astrophysics Data System (ADS)

Yu, Zhitao; Miller, Franklin; Pfotenhauer, John M.

2017-12-01

Both a numerical and analytical model of the heat and mass transfer processes in a CO2, N2 mixture gas de-sublimating cross-flow finned duct heat exchanger system is developed to predict the heat transferred from a mixture gas to liquid nitrogen and the de-sublimating rate of CO2 in the mixture gas. The mixture gas outlet temperature, liquid nitrogen outlet temperature, CO2 mole fraction, temperature distribution and de-sublimating rate of CO2 through the whole heat exchanger was computed using both the numerical and analytic model. The numerical model is built using EES [1] (engineering equation solver). According to the simulation, a cross-flow finned duct heat exchanger can be designed and fabricated to validate the models. The performance of the heat exchanger is evaluated as functions of dimensionless variables, such as the ratio of the mass flow rate of liquid nitrogen to the mass flow rate of inlet flue gas.

Risk of hydrocyanic acid release in the electroplating industry.

PubMed

Piccinini, N; Ruggiero, G N; Baldi, G; Robotto, A

2000-01-07

This paper suggests assessing the consequences of hydrocyanic acid (HCN) release into the air by aqueous cyanide solutions in abnormal situations such as the accidental introduction of an acid, or the insertion of a cyanide in a pickling bath. It provides a well-defined source model and its resolution by methods peculiar to mass transport phenomena. The procedure consists of four stages: calculation of the liquid phase concentration, estimate of the HCN liquid-vapour equilibrium, determination of the mass transfer coefficient at the liquid-vapour interface, evaluation of the air concentration of HCN and of the damage distances. The results show that small baths operating at high temperatures are the major sources of risk. The building up of lethal air concentrations, on the other hand, is governed by the values of the mass transfer coefficient, which is itself determined by the flow dynamics and bath geometry. Concerning the magnitude of the risk, the fallout for external emergency planning is slight in all the cases investigated.

Airborne ultrasound for the precipitation of smokes and powders and the destruction of foams.

PubMed

Riera, Enrique; Gallego-Juárez, Juan A; Mason, Timothy J

2006-02-01

Sonochemistry is generally associated with the use of power ultrasound in liquid media. Under such circumstances acoustic cavitation can drive a range of reactions and processes. The use of airborne ultrasound in processing is less familiar because of the difficulties that relate to the use of ultrasound in gaseous systems. Firstly there is a greater attenuation (power loss) in the transmission of sound through air compared with that through liquid. Secondly the transfer of acoustic energy generated in air into a liquid or solid material is inefficient due to the mismatch between acoustic impedances of gases and solids or liquids. Despite this, applications do exist for airborne ultrasound but the source must be very powerful and efficient. In this way one can obtain levels of intensities at which it is possible to use ultrasound for specific applications such as to agglomerate fine dusts and to break down foams.

Origin of Self-preservation Effect for Hydrate Decomposition: Coupling of Mass and Heat Transfer Resistances

PubMed Central

Bai, Dongsheng; Zhang, Diwei; Zhang, Xianren; Chen, Guangjin

2015-01-01

Gas hydrates could show an unexpected high stability at conditions out of thermodynamic equilibrium, which is called the self-preservation effect. The mechanism of the effect for methane hydrates is here investigated via molecular dynamics simulations, in which an NVT/E method is introduced to represent different levels of heat transfer resistance. Our simulations suggest a coupling between the mass transfer resistance and heat transfer resistance as the driving mechanism for self-preservation effect. We found that the hydrate is initially melted from the interface, and then a solid-like water layer with temperature-dependent structures is formed next to the hydrate interface that exhibits fractal feature, followed by an increase of mass transfer resistance for the diffusion of methane from hydrate region. Furthermore, our results indicate that heat transfer resistance is a more fundamental factor, since it facilitates the formation of the solid-like layer and hence inhibits the further dissociation of the hydrates. The self-preservation effect is found to be enhanced with the increase of pressure and particularly the decrease of temperature. Kinetic equations based on heat balance calculations is also developed to describe the self-preservation effect, which reproduces our simulation results well and provides an association between microscopic and macroscopic properties. PMID:26423519

Origin of Self-preservation Effect for Hydrate Decomposition: Coupling of Mass and Heat Transfer Resistances.

PubMed

Bai, Dongsheng; Zhang, Diwei; Zhang, Xianren; Chen, Guangjin

2015-10-01

Gas hydrates could show an unexpected high stability at conditions out of thermodynamic equilibrium, which is called the self-preservation effect. The mechanism of the effect for methane hydrates is here investigated via molecular dynamics simulations, in which an NVT/E method is introduced to represent different levels of heat transfer resistance. Our simulations suggest a coupling between the mass transfer resistance and heat transfer resistance as the driving mechanism for self-preservation effect. We found that the hydrate is initially melted from the interface, and then a solid-like water layer with temperature-dependent structures is formed next to the hydrate interface that exhibits fractal feature, followed by an increase of mass transfer resistance for the diffusion of methane from hydrate region. Furthermore, our results indicate that heat transfer resistance is a more fundamental factor, since it facilitates the formation of the solid-like layer and hence inhibits the further dissociation of the hydrates. The self-preservation effect is found to be enhanced with the increase of pressure and particularly the decrease of temperature. Kinetic equations based on heat balance calculations is also developed to describe the self-preservation effect, which reproduces our simulation results well and provides an association between microscopic and macroscopic properties.

Simultaneous analysis of gemfibrozil, morphine, and its two active metabolites in different mouse brain structures using solid-phase extraction with ultra-high performance liquid chromatography and tandem mass spectrometry with a deuterated internal standard.

PubMed

Yang, Zizhao; Wang, Lu; Xu, Mingcheng; Gu, Jingkai; Yu, Lushan; Zeng, Su

2016-06-01

A rapid and sensitive bioassay was established and validated to simultaneously determine gemfibrozil, morphine, morphine-3β-glucuronide, and morphine-6β-glucuronide in mouse cerebrum, epencephalon, and hippocampus based on ultra-high performance liquid chromatography and tandem mass spectrometry. The deuterated internal standard, M6G-d3, was mixed with the prepared samples at 10 ng/mL as the final concentration. The samples were transferred into the C18 solid-phase extraction columns with gradient elution for solid-phase extraction. The mobile phase consisted of methanol and 0.05% formic acid (pH 3.2). Multiple reaction monitoring has been applied to analyze gemfibrozil (m/z 249.0 → 121.0) in anion mode, and M6G-d3 (m/z 465.1 → 289.1), morphine (m/z 286.0 → 200.9), and M3G and M6G (m/z 462.1 → 286.1) in the positive ion mode. The method has a linear calibration range from 0.05 to 10 ng for gemfibrozil, morphine, and M3G and M6G with correlation coefficients >0.993. The lower limit of quantitation for all four analytes was 0.05 ng/mL, relative standard deviation of intra- and interday precision was less than 10.5%, and the relative error of accuracy was from -8.2 to 8.3% at low, medium, and high concentrations for all the analytes. In conclusion, gemfibrozil can influence the morphine antinociception after coronary heart disease induced chronic angina by the change in one of morphine metabolites', M3G, distribution in mouse brain. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

All-solid-state flexible supercapacitors based on papers coated with carbon nanotubes and ionic-liquid-based gel electrolytes.

PubMed

Kang, Yu Jin; Chung, Haegeun; Han, Chi-Hwan; Kim, Woong

2012-02-17

All-solid-state flexible supercapacitors were fabricated using carbon nanotubes (CNTs), regular office papers, and ionic-liquid-based gel electrolytes. Flexible electrodes were made by coating CNTs on office papers by a drop-dry method. The gel electrolyte was prepared by mixing fumed silica nanopowders with ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][NTf(2)]). This supercapacitor showed high power and energy performance as a solid-state flexible supercapacitor. The specific capacitance of the CNT electrodes was 135 F g(-1) at a current density of 2 A g(-1), when considering the mass of active materials only. The maximum power and energy density of the supercapacitors were 164 kW kg(-1) and 41 Wh kg(-1), respectively. Interestingly, the solid-state supercapacitor with the gel electrolyte showed comparable performance to the supercapacitors with ionic-liquid electrolyte. Moreover, the supercapacitor showed excellent stability and flexibility. The CNT/paper- and gel-based supercapacitors may hold great potential for low-cost and high-performance flexible energy storage applications.

All-solid-state flexible supercapacitors based on papers coated with carbon nanotubes and ionic-liquid-based gel electrolytes

NASA Astrophysics Data System (ADS)

Kang, Yu Jin; Chung, Haegeun; Han, Chi-Hwan; Kim, Woong

2012-02-01

All-solid-state flexible supercapacitors were fabricated using carbon nanotubes (CNTs), regular office papers, and ionic-liquid-based gel electrolytes. Flexible electrodes were made by coating CNTs on office papers by a drop-dry method. The gel electrolyte was prepared by mixing fumed silica nanopowders with ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][NTf2]). This supercapacitor showed high power and energy performance as a solid-state flexible supercapacitor. The specific capacitance of the CNT electrodes was 135 F g-1 at a current density of 2 A g-1, when considering the mass of active materials only. The maximum power and energy density of the supercapacitors were 164 kW kg-1 and 41 Wh kg-1, respectively. Interestingly, the solid-state supercapacitor with the gel electrolyte showed comparable performance to the supercapacitors with ionic-liquid electrolyte. Moreover, the supercapacitor showed excellent stability and flexibility. The CNT/paper- and gel-based supercapacitors may hold great potential for low-cost and high-performance flexible energy storage applications.

3-D Distribution of Retained Colloids in Unsaturated Porous Media

NASA Astrophysics Data System (ADS)

Morales, V. L.; Perez-Reche, F. J.; Holzner, M.; Kinzelbach, W. K.; Otten, W.

2013-12-01

It is well accepted that colloid transport processes in porous media differ substantially between water saturated and unsaturated conditions. Differences are frequently ascribed to colloid immobilization by association with interfaces with the gas, as well as to restrictions of the liquid medium through which colloids are transported. Such factors depend on interfacial conditions provided by the water saturation of the porous medium. Yet, the current understanding of the importance of colloid retention at gas interfaces is based on observations of single pores or two-dimensional pore network representations, leaving open the question of their statistical significance when all pores in the medium are considered. In order to address this question, column experiments were performed using a model porous medium of glass beads through which colloidal silver particles were transported for conditions of varying water content. X-ray microtomography was subsequently employed as a non-destructive imaging technique to obtain pore-scale information of the entire column regarding: i) the presence and distribution of the four main locations where colloids can become retained (interfaces with the liquid-solid, gas-liquid and gas-solid, and the bulk liquid), ii) deposition profiles of colloids along the column classified by the available retention location, iii) morphological characteristics of the deposited colloidal aggregates, and iv) channel widths of 3-dimensional pore-water network representations. The results presented provide, for the first time, a direct statistical evaluation on the significance of colloid retention by attachment to the liquid-solid, gas-liquid, gas-solid interfaces, and by straining in the bulk liquid. Additionally, an effective-pore structure characteristic is proposed to improve predictions of mass removal by straining under various water saturations. A) Unsaturated conditions. B) Saturated conditions. Left: Tomograph slice illustrating with false coloring Regions Of Interest corresponding to retention locations at the gas-liquid (purple), gas-solid (white) and solid-liquid interface (blue), and the bulk liquid (teal). Right: Deposition profiles of silver colloids (Ag) per retention location (T: total, GLI: gas-liquid interface, GSI: gas-solid interface, SLI: solid-liquid interface, L: bulk liquid) (Top). Depth profiles of the volume occupied by each retention location (Middle). Normalized deposition profiles of silver volume retained by its corresponding retention-location volume (Bottom).

Quantitative and Qualitative Aspects of Gas-Metal-Oxide Mass Transfer in High-Temperature Confocal Scanning Laser Microscopy

NASA Astrophysics Data System (ADS)

Piva, Stephano P. T.; Pistorius, P. Chris; Webler, Bryan A.

2018-05-01

During high-temperature confocal scanning laser microscopy (HT-CSLM) of liquid steel samples, thermal Marangoni flow and rapid mass transfer between the sample and its surroundings occur due to the relatively small sample size (diameter around 5 mm) and large temperature gradients. The resulting evaporation and steel-slag reactions tend to change the chemical composition in the metal. Such mass transfer effects can change observed nonmetallic inclusions. This work quantifies oxide-metal-gas mass transfer of solutes during HT-CSLM experiments using computational simulations and experimental data for (1) dissolution of MgO inclusions in the presence and absence of slag and (2) Ca, Mg-silicate inclusion changes upon exposure of a Si-Mn-killed steel to an oxidizing gas atmosphere.

Heat and mass transfer of liquid nitrogen in coal porous media

NASA Astrophysics Data System (ADS)

Lang, Lu; Chengyun, Xin; Xinyu, Liu

2018-04-01

Liquid nitrogen has been working as an important medium in fire extinguishing and prevention, due to its efficiency in oxygen exclusion and heat removal. Such a technique is especially crucial for coal industry in China. We built a tunnel model with a temperature monitor system (with 36 thermocouples installed) to experimentally study heat and mass transfer of liquid nitrogen in non-homogeneous coal porous media (CPM), and expected to optimize parameters of liquid nitrogen injection in engineering applications. Results indicate that injection location and amount of liquid nitrogen, together with air leakage, significantly affect temperature distribution in CPM, and non-equilibrium heat inside and outside of coal particles. The injection position of liquid nitrogen determines locations of the lowest CPM temperature and liquid nitrogen residual. In the deeper coal bed, coal particles take longer time to reach thermal equilibrium between their surface and inside. Air leakage accelerates temperature increase at the bottom of the coal bed, which is a major reason leading to fire prevention inefficiency. Measurement fluctuation of CPM temperature may be caused by incomplete contact of coal particles with liquid nitrogen flowing in the coal bed. Moreover, the secondary temperature drop (STD) happens and grows with the more injection of liquid nitrogen, and the STD phenomenon is explained through temperature distributions at different locations.

Ionic liquid electrolytes for dye-sensitized solar cells.

PubMed

Gorlov, Mikhail; Kloo, Lars

2008-05-28

The potential of room-temperature molten salts (ionic liquids) as solvents for electrolytes for dye-sensitized solar cells has been investigated during the last decade. The non-volatility, good solvent properties and high electrochemical stability of ionic liquids make them attractive solvents in contrast to volatile organic solvents. Despite this, the relatively high viscosity of ionic liquids leads to mass-transport limitations. Here we review recent developments in the application of different ionic liquids as solvents or components of liquid and quasi-solid electrolytes for dye-sensitized solar cells.

Aerogel Insulation Applications for Liquid Hydrogen Launch Vehicle Tanks

NASA Technical Reports Server (NTRS)

Fesmire, J. E.; Sass, J.

2007-01-01

Aerogel based insulation systems for ambient pressure environments were developed for liquid hydrogen (LH2) tank applications. Solutions to thermal insulation problems were demonstrated for the Space Shuttle External Tank (ET) through extensive testing at the Cryogenics Test Laboratory. Demonstration testing was performed using a 1/10th scale ET LH2 intertank unit and liquid helium as the coolant to provide the 20 K cold boundary temperature. Cryopumping tests in the range of 20K were performed using both constant mass and constant pressure methods. Long-duration tests (up to 10 hours) showed that the nitrogen mass taken up inside the intertank is reduced by a factor of nearly three for the aerogel insulated case as compared to the un-insulated (bare metal flight configuration) case. Test results including thermal stabilization, heat transfer effectiveness, and cryopumping confirm that the aerogel system eliminates free liquid nitrogen within the intertank. Physisorption (or adsorption) of liquid nitrogen within the fine pore structure of aerogel materials was also investigated. Results of a mass uptake method show that the sorption ratio (liquid nitrogen to aerogel beads) is about 62 percent by volume. A novel liquid nitrogen production method of testing the liquid nitrogen physical adsorption capacity of aerogel beads was also performed to more closely approximate the actual launch vehicle cooldown and thermal stabilization effects within the aerogel material. The extraordinary insulating effectiveness of the aerogel material shows that cryopumping is not an open-cell mass transport issue but is strictly driven by thermal communication between warm and cold surfaces. The new aerogel insulation technology is useful to solve heat transfer problem areas and to augment existing thermal protection systems on launch vehicles. Examples are given and potential benefits for producing launch systems that are more reliable, robust, reusable, and efficient are outlined.

MEMBRANE BIOTREATMENT OF VOC-LADEN AIR

EPA Science Inventory

The paper discusses membrane biotreatment of air laden with volatile organic compounds (VOCs). Microporous flat-sheet and hollow-fiber membrane contactors were used to support air-liquid mass transfer interfaces. These modules were used in a two-step process to transfer VOCs fr...

The numerical approach adopted in toba computer code for mass and heat transfer dynamic analysis of metal hydride hydrogen storage beds

DOE Office of Scientific and Technical Information (OSTI.GOV)

El Osery, I.A.

1983-12-01

Modelling studies of metal hydride hydrogen storage beds is a part of an extensive R and D program conducted in Egypt on hydrogen energy. In this context two computer programs; namely RET and RET1; have been developed. In RET computer program, a cylindrical conduction bed model is considered and an approximate analytical solution is used for solution of the associated mass and heat transfer problem. This problem is solved in RET1 computer program numerically allowing more flexibility in operating conditions but still limited to cylindrical configuration with only two alternatives for heat exchange; either fluid is passing through tubes imbeddedmore » in the solid alloy matrix or solid rods are surrounded by annular fluid tubes. The present computer code TOBA is more flexible and realistic. It performs the mass and heat transfer dynamic analysis of metal hydride storage beds using a variety of geometrical and operating alternatives.« less

Magnetic nanoparticles stimulation to enhance liquid-liquid two-phase mass transfer under static and rotating magnetic fields

NASA Astrophysics Data System (ADS)

Azimi, Neda; Rahimi, Masoud

2017-01-01

Rotating magnetic field (RMF) was applied on a micromixer to break the laminar flow and induce chaotic flow to enhance mass transfer between two-immiscible organic and aqueous phases. The results of RMF were compared to those of static magnetic field (SMF). For this purpose, experiments were carried out in a T-micromixer at equal volumetric flow rates of organic and aqueous phases. Fe3O4 nanoparticles were synthesized by co-precipitation technique and they were dissolved in organic phase. Results obtained from RMF and SMF were compared in terms of overall volumetric mass transfer coefficient (KLa) and extraction efficiency (E) at various Reynolds numbers. Generally, RMF showed higher effect in mass transfer characteristics enhancement compared with SMF. The influence of rotational speeds of magnets (ω) in RMF was investigated, and measurable enhancements of KLa and E were observed. In RMF, the effect of magnetic field induction (B) was investigated. The results reveal that at constant concentration of nanoparticles, by increasing of B, mass transfer characteristics will be enhanced. The effect of various nanoparticles concentrations (ϕ) within 0.002-0.01 (w/v) on KLa and E at maximum induction of RMF (B=76 mT) was evaluated. Maximum values of KLa (2.1±0.001) and E (0.884±0.001) were achieved for the layout of RMF (B=76 mT), ω=16 rad/s and MNPs concentration of 0.008-0.01 (w/v).

Studies on fluid dynamics of the flow field and gas transfer in orbitally shaken tubes.

PubMed

Zhu, Li-Kuan; Song, Bo-Yan; Wang, Zhen-Long; Monteil, Dominique T; Shen, Xiao; Hacker, David L; De Jesus, Maria; Wurm, Florian M

2017-01-01

Orbitally shaken cylindrical bioreactors [OrbShake bioreactors (OSRs)] without an impeller or sparger are increasingly being used for the suspension cultivation of mammalian cells. Among small volume OSRs, 50-mL tubes with a ventilated cap (OSR50), originally derived from standard laboratory centrifuge tubes with a conical bottom, have found many applications including high-throughput screening for the optimization of cell cultivation conditions. To better understand the fluid dynamics and gas transfer rates at the liquid surface in OSR50, we established a three-dimensional simulation model of the unsteady liquid forms (waves) in this vessel. The studies verified that the operating conditions have a large effect on the interfacial surface. The volumetric mass transfer coefficient (k L a) was determined experimentally and from simulations under various working conditions. We also determined the liquid-phase mass transfer coefficient (k L ) and the specific interfacial area (a) under different conditions to demonstrate that the value of a affected the gas transfer rate more than did the value of k L . High oxygen transfer rates, sufficient for supporting the high-density culture of mammalian cells, were found. Finally, the average axial velocity of the liquid was identified to be an important parameter for maintaining cells in suspension. Overall these studies provide valuable insights into the preferable operating conditions for the OSR50, such as those needed for cell cultures requiring high oxygen levels. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 33:192-200, 2017. © 2016 American Institute of Chemical Engineers.

Research on Volume Measurement System of Weights with Hydrostatic Technique

NASA Astrophysics Data System (ADS)

Wang, Jian; Ren, Xiaoping; Yao, Hong; Cai, Changqing; Zhang, Yue; Zhong, Ruilin; Ding, Jing'an

According to Annex B.7.4 of OIML R111-1, equipment for measuring volume of weights mass ranging from 1 kg to 20 kg including three methods of hydrostatic comparison is described. The equipment consists of a robot arm for transferring weights, a liquid bath, a mass comparator with 26.1 kg of maximum capacity and 1 mg of readability, glass housing, two weight exchangers including in air and in liquid, two weight holders including in air and in liquid, and a controller. The equipment will enable to perform automatically volume measurements.

Quantitation of acrylamide in foods by high-resolution mass spectrometry.

PubMed

Troise, Antonio Dario; Fiore, Alberto; Fogliano, Vincenzo

2014-01-08

Acrylamide detection still represents one of the hottest topics in food chemistry. Solid phase cleanup coupled to liquid chromatography separation and tandem mass spectrometry detection along with GC-MS detection are nowadays the gold standard procedure for acrylamide quantitation thanks to high reproducibility, good recovery, and low relative standard deviation. High-resolution mass spectrometry (HRMS) is particularly suitable for the detection of low molecular weight amides, and it can provide some analytical advantages over other MS techniques. In this paper a liquid chromatography (LC) method for acrylamide determination using HRMS detection was developed and compared to LC coupled to tandem mass spectrometry. The procedure applied a simplified extraction, no cleanup steps, and a 4 min chromatography. It proved to be solid and robust with an acrylamide mass accuracy of 0.7 ppm, a limit of detection of 2.65 ppb, and a limit of quantitation of 5 ppb. The method was tested on four acrylamide-containing foods: cookies, French fries, ground coffee, and brewed coffee. Results were perfectly in line with those obtained by LC-MS/MS.

Simultaneous Determination of Perfluorinated Compounds in Edible Oil by Gel-Permeation Chromatography Combined with Dispersive Solid-Phase Extraction and Liquid Chromatography-Tandem Mass Spectrometry.

PubMed

Yang, Lili; Jin, Fen; Zhang, Peng; Zhang, Yanxin; Wang, Jian; Shao, Hua; Jin, Maojun; Wang, Shanshan; Zheng, Lufei; Wang, Jing

2015-09-30

A simple analytical method was developed for the simultaneous analysis of 18 perfluorinated compounds (PFCs) in edible oil. The target compounds were extracted by acetonitrile, purified by gel permeation chromatography (GPC) and dispersive solid-phase extraction (DSPE) using graphitized carbon black (GCB) and octadecyl (C18), and analyzed by liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ES-MS/MS) in negative ion mode. Recovery studies were performed at three fortification levels. The average recoveries of all target PFCs ranged from 60 to 129%, with an acceptable relative standard deviation (RSD) (1-20%, n = 3). The method detection limits (MDLs) ranged from 0.004 to 0.4 μg/kg, which was significantly improved compared with the existing liquid-liquid extraction and cleanup method. The method was successfully applied for the analysis of all target PFCs in edible oil samples collected from markets in Beijing, China, and the results revealed that C6-C10 perfluorocarboxylic acid (PFCAs) and C7 perfluorosulfonic acid PFSAs were the major PFCs detected in oil samples.

A comparison of mass transfer coefficients between trickle-bed, hollow fiber membrane and stirred tank reactors.

PubMed

Orgill, James J; Atiyeh, Hasan K; Devarapalli, Mamatha; Phillips, John R; Lewis, Randy S; Huhnke, Raymond L

2013-04-01

Trickle-bed reactor (TBR), hollow fiber membrane reactor (HFR) and stirred tank reactor (STR) can be used in fermentation of sparingly soluble gasses such as CO and H2 to produce biofuels and bio-based chemicals. Gas fermenting reactors must provide high mass transfer capabilities that match the kinetic requirements of the microorganisms used. The present study compared the volumetric mass transfer coefficient (K(tot)A/V(L)) of three reactor types; the TBR with 3 mm and 6 mm beads, five different modules of HFRs, and the STR. The analysis was performed using O2 as the gaseous mass transfer agent. The non-porous polydimethylsiloxane (PDMS) HFR provided the highest K(tot)A/V(L) (1062 h(-1)), followed by the TBR with 6mm beads (421 h(-1)), and then the STR (114 h(-1)). The mass transfer characteristics in each reactor were affected by agitation speed, and gas and liquid flow rates. Furthermore, issues regarding the comparison of mass transfer coefficients are discussed. Copyright © 2013 Elsevier Ltd. All rights reserved.

Conceptual models governing leaching behavior and their long-term predictive capability

USGS Publications Warehouse

Claassen, Hans C.

1981-01-01

Six models that may be used to describe the interaction of radioactive waste solids with aqueous solutions are as follows:Simple linear mass transfer;Simple parabolic mass transfer;Parabolic mass transfer with the formation of a diffusion-limiting surface layer at an arbitrary time;Initial parabolic mass transfer followed by linear mass transfer at an arbitrary time;Parabolic (or linear) mass transfer and concomitant surface sorption; andParabolic (or linear) mass transfer and concomitant chemical precipitation.Some of these models lead to either illogical or unrealistic predictions when published data are extrapolated to long times. These predictions result because most data result from short-term experimentation. Probably for longer times, processes will occur that have not been observed in the shorter experiments. This hypothesis has been verified by mass-transfer data from laboratory experiments using natural volcanic glass to predict the composition of groundwater. That such rate-limiting mechanisms do occur is reassuring, although now it is not possible to deduce a single mass-transfer limiting mechanism that could control the solution concentration of all components of all waste forms being investigated. Probably the most reasonable mechanisms are surface sorption and chemical precipitation of the species of interest. Another is limiting of mass transfer by chemical precipitation on the waste form surface of a substance not containing the species of interest, that is, presence of a diffusion-limiting layer. The presence of sorption and chemical precipitation as factors limiting mass transfer has been verified in natural groundwater systems, whereas the diffusion-limiting mechanism has not been verified yet.

Broad screening and identification of β-agonists in feed and animal body fluid and tissues using ultra-high performance liquid chromatography-quadrupole-orbitrap high resolution mass spectrometry combined with spectra library search.

PubMed

Li, Tingting; Cao, Jingjing; Li, Zhen; Wang, Xian; He, Pingli

2016-02-01

Broad screening and identification of β-agonists in feed, serum, urine, muscle and liver samples was achieved in a quick and highly sensitive manner using ultra high performance liquid chromatography-quadrupole-orbitrap high resolution mass spectrometry (UHPLC-Q-Orbitrap HRMS) combined with a spectra library search. Solid-phase extraction technology was employed for sample purification and enrichment. After extraction and purification, the samples were analyzed using a Q-Orbitrap high-resolution mass spectrometer under full-scan and data-dependent MS/MS mode. The acquired mass spectra were compared with an in-house library (compound library and MS/MS mass spectral library) built with TraceFinder Software which contained the M/Z of the precursor ion, chemical formula, retention time, character fragment ions and the entire MS/MS spectra of 32 β-agonist standards. Screening was achieved by comparing 5 key mass spectral results and positive matches were marked. Using the developed method, the identification results from 10 spiked samples and 238 actual samples indicated that only 2% of acquired mass spectra produced false identities. The method validation results showed that the limit of detection ranged from 0.021-3.854 μg kg(-1)and 0.015-1.198 ng mL(-1) for solid and liquid samples, respectively. Copyright © 2015 Elsevier Ltd. All rights reserved.

Desorption in Mass Spectrometry

PubMed Central

Usmanov, Dilshadbek Tursunbayevich; Ninomiya, Satoshi; Chen, Lee Chuin; Saha, Subhrakanti; Mandal, Mridul Kanti; Sakai, Yuji; Takaishi, Rio; Habib, Ahsan; Hiraoka, Kenzo; Yoshimura, Kentaro; Takeda, Sen; Wada, Hiroshi; Nonami, Hiroshi

2017-01-01

In mass spectrometry, analytes must be released in the gas phase. There are two representative methods for the gasification of the condensed samples, i.e., ablation and desorption. While ablation is based on the explosion induced by the energy accumulated in the condensed matrix, desorption is a single molecular process taking place on the surface. In this paper, desorption methods for mass spectrometry developed in our laboratory: flash heating/rapid cooling, Leidenfrost phenomenon-assisted thermal desorption (LPTD), solid/solid friction, liquid/solid friction, electrospray droplet impact (EDI) ionization/desorption, and probe electrospray ionization (PESI), will be described. All the methods are concerned with the surface and interface phenomena. The concept of how to desorb less-volatility compounds from the surface will be discussed. PMID:28337398

Heat Transfer to a Thin Solid Combustible in Flame Spreading at Microgravity

NASA Technical Reports Server (NTRS)

Bhattacharjee, S.; Altenkirch, R. A.; Olson, S. L.; Sotos, R. G.

1991-01-01

The heat transfer rate to a thin solid combustible from an attached diffusion flame, spreading across the surface of the combustible in a quiescent, microgravity environment, was determined from measurements made in the drop tower facility at NASA-Lewis Research Center. With first-order Arrhenius pyrolysis kinetics, the solid-phase mass and energy equations along with the measured spread rate and surface temperature profiles were used to calculate the net heat flux to the surface. Results of the measurements are compared to the numerical solution of the complete set of coupled differential equations that describes the temperature, species, and velocity fields in the gas and solid phases. The theory and experiment agree on the major qualitative features of the heat transfer. Some fundamental differences are attributed to the neglect of radiation in the theoretical model.

TECHNOLOGY TRANSFER HANDBOOK: MANAGEMENT OF WATER TREATMENT PLANT RESIDUALS

EPA Science Inventory

Potable water treatment processes produce safe drinking water and generate a wide variety of waste products known as residuals, including organic and inorganic compounds in liquid, solid, and gaseous forms. In the current regulatory climate, a complete management program for a w...

In situ solid-state electrochemistry of mass-selected ions at well-defined electrode–electrolyte interfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prabhakaran, Venkateshkumar; Johnson, Grant E.; Wang, Bingbing

2016-11-07

Molecular-level understanding of electrochemical processes occurring at electrode-electrolyte interfaces (EEI) is key to the rational development of high-performance and sustainable electrochemical technologies. This article reports the development and first application of solid-state in situ electrochemical probes to study redox and catalytic processes occurring at well-defined EEI generated using soft-landing of mass- and charge-selected cluster ions (SL). In situ electrochemical probes with excellent mass transfer properties are fabricated using carefully-designed nanoporous ionic liquid membranes. SL enables deposition of pure active species that are not obtainable with other techniques onto electrode surfaces with precise control over charge state, composition, and kinetic energy.more » SL is, therefore, a unique tool for studying fundamental processes occurring at EEI. For the first time using an aprotic electrochemical probe, the effect of charge state (PMo12O403-/2-) and the contribution of building blocks of Keggin polyoxometalate (POM) clusters to redox processes are characterized by populating EEI with novel POM anions generated by electrospray ionization and gas phase dissociation. Additionally, a proton conducting electrochemical probe has been developed to characterize the reactive electrochemistry (oxygen reduction activity) of bare Pt clusters (Pt40 ~1 nm diameter), thus demonstrating the capability of the probe for studying reactions in controlled gaseous environments. The newly developed in situ electrochemical probes combined with ion SL provide a versatile method to characterize the EEI in solid-state redox systems and reactive electrochemistry at precisely-defined conditions. This capability will advance molecular-level understanding of processes occurring at EEI that are critical to many energy-related technologies.« less

Experimental Assessment of the Mass of Ash Residue During the Burning of Droplets of a Composite Liquid Fuel

NASA Astrophysics Data System (ADS)

Glushkov, D. O.; Zakharevich, A. V.; Strizhak, P. A.; Syrodoi, S. V.

2018-03-01

An experimental study has been made of the regularities of burning of single droplets of typical compositions of a composite liquid fuel during the heating by an air flow with a varied temperature (600-900 K). As the basic components of the compositions of the composite liquid fuel, use was made of the: waste of processing (filter cakes) of bituminous coals of ranks K, C, and T, waste motor, turbine, and transformer oils, process mixture of mazut and oil, heavy crude, and plasticizer. The weight fraction of a liquid combustible component (petroleum) product) ranged within 0-15%. Consideration has been given to droplets of a composite liquid fuel with dimensions (radius) of 0.5 to 2 mm. Conditions of low-temperature initiation of combustion to ensure a minimum possible mass of solid incombustible residue have been determined. Petroleum products have been singled out whose addition to the composition of the composite liquid fuel tends to increase the ash mass (compared to the corresponding composition without a liquid combustible component). Approximation dependences have been obtained which permit predicting the influence of the concentration of the liquid petroleum product as part of the composite liquid fuel on the ash-residue mass.

Experimental Assessment of the Mass of Ash Residue During the Burning of Droplets of a Composite Liquid Fuel

NASA Astrophysics Data System (ADS)

Glushkov, D. O.; Zakharevich, A. V.; Strizhak, P. A.; Syrodoi, S. V.

2018-05-01

An experimental study has been made of the regularities of burning of single droplets of typical compositions of a composite liquid fuel during the heating by an air flow with a varied temperature (600-900 K). As the basic components of the compositions of the composite liquid fuel, use was made of the: waste of processing (filter cakes) of bituminous coals of ranks K, C, and T, waste motor, turbine, and transformer oils, process mixture of mazut and oil, heavy crude, and plasticizer. The weight fraction of a liquid combustible component (petroleum) product) ranged within 0-15%. Consideration has been given to droplets of a composite liquid fuel with dimensions (radius) of 0.5 to 2 mm. Conditions of low-temperature initiation of combustion to ensure a minimum possible mass of solid incombustible residue have been determined. Petroleum products have been singled out whose addition to the composition of the composite liquid fuel tends to increase the ash mass (compared to the corresponding composition without a liquid combustible component). Approximation dependences have been obtained which permit predicting the influence of the concentration of the liquid petroleum product as part of the composite liquid fuel on the ash-residue mass.

Study of the laser-induced forward transfer of liquids for laser bioprinting

NASA Astrophysics Data System (ADS)

Duocastella, M.; Colina, M.; Fernández-Pradas, J. M.; Serra, P.; Morenza, J. L.

2007-07-01

Laser-induced forward transfer (LIFT) is a direct-writing technique that allows printing patterns of diverse materials with a high degree of spatial resolution. In conventional LIFT a small fraction of a solid thin film is vaporized by means of a laser pulse focused on the film through its transparent holder, and the resulting material recondenses on the receptor substrate. It has been recently shown that LIFT can also be used to transfer materials from liquid films. This widened its field of application to biosensors manufacturing, where small amounts of biomolecules-containing solutions have to be deposited with high precision on the sensing elements. However, there is still little knowledge on the physical processes and parameters determining the characteristics of the transfers. In this work, different parameters and their effects upon the transferred material were studied. It was found that the deposited material corresponds to liquid droplets which volume depends linearly on the laser pulse energy, and that a minimum threshold energy has to be overcome for transfer to occur. The liquid film thickness was varied and droplets as small as 10 μm in diameter were obtained. Finally, the effects of the variation of the film to substrate distance were also studied and it was found that there exists a wide range of distances where the morphology of the transferred droplets is independent of this parameter, what provides LIFT with a high degree of flexibility.

Interferometric study on the mass transfer in cryogenic distillation under magnetic field

NASA Astrophysics Data System (ADS)

Bao, S. R.; Zhang, R. P.; Y Rong, Y.; Zhi, X. Q.; Qiu, L. M.

2017-12-01

Cryogenic distillation has long been used for the mass production of industrial gases because of its features of high efficiency, high purity, and capability to produce noble gases. It is of great theoretical and practical significance to explore methods to improve the mass transfer efficiency in cryogenic distillation. The negative correlation between the susceptibility of paramagnetic oxygen and temperature provides a new possibility of comprehensive utilization of boiling point and susceptibility differences in cryogenic distillation. Starting from this concept, we proposed a novel distillation intensifying method by using gradient magnetic field, in which the magnetic forces enhance the transport of the oxygen molecules to the liquid phase in the distillation. In this study, a cryogenic testbed was designed and fabricated to study the diffusion between oxygen and nitrogen under magnetic field. A Mach-Zehnder interferometer was used to visualize the concentration distribution during the diffusion process. The mass transfer characteristics with and without magnetic field, in the chamber filled with the magnetized medium, were systematically studied. The concentration redistribution of oxygen was observed, and the stable stratified diffusion between liquid oxygen and nitrogen was prolonged by the non-uniform magnetic field. The experimental results show that the magnetic field can efficiently influence the mass transfer in cryogenic distillation, which can provide a new mechanism for the optimization of air separation process.

A molecular dynamics study of thermal transport in nanoparticle doped Argon like solid

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shahadat, Muhammad Rubayat Bin, E-mail: rubayat37@gmail.com; Ahmed, Shafkat; Morshed, A. K. M. M.

2016-07-12

Interfacial phenomena such as mass and type of the interstitial atom, nano scale material defect influence heat transfer and the effect become very significant with the reduction of the material size. Non Equilibrium Molecular Dynamics (NEMD) simulation was carried out in this study to investigate the effect of the interfacial phenomena on solid. Argon like solid was considered in this study and LJ potential was used for atomic interaction. Nanoparticles of different masses and different molecular defects were inserted inside the solid. From the molecular simulation, it was observed that a large interfacial mismatch due to change in mass inmore » the homogenous solid causes distortion of the phonon frequency causing increase in thermal resistance. Position of the doped nanoparticles have more profound effect on the thermal conductivity of the solid whereas influence of the mass ratio is not very significant. Interstitial atom positioned perpendicular to the heat flow causes sharp reduction in thermal conductivity. Structural defect caused by the molecular defect (void) also observed to significantly affect the thermal conductivity of the solid.« less

Matrix solid-phase dispersion followed by liquid chromatography tandem mass spectrometry for the determination of selective ciclooxygenase-2 inhibitors in sewage sludge samples.

PubMed

Triñanes, Sara; Casais, M Carmen; Mejuto, M Carmen; Cela, Rafael

2016-09-02

A straightforward single-step extraction method based on matrix solid-phase dispersion (MSPD), followed by high-performance liquid chromatography with hybrid quadrupole time of flight mass spectrometry (LC-QTOF-MS), was developed and optimized to determine five non-steroidal anti-inflammatory drugs (Valdecoxib, Etoricoxib, Parecoxib, Celecoxib and 2,5-Dimethylcelecoxib) in sewage sludge samples. The influence of different operational parameters on the extraction efficiency a well as in the matrix effects of the produced extracts was evaluated in detail. Under final working conditions, freeze dried samples (0.2g) were first soaked with 100μL of aqueous potassium hydroxide solution (60%, w/v), mixed with 1g of anhydrous sodium sulfate and dispersed with 1g of Florisil. This blend was transferred to the top of a polypropylene column cartridge containing 3g of silica. Analytes were recovered using 15mL of hexane/acetone (1:2, v/v) mixture. The extracts were concentrated by evaporation and reconstituted with 1mL of methanol/water (1:1, v/v), filtered and injected in the LC system. Quantification limits from 0.005 and 0.05ngg(-1) and absolute recoveries between 86 and 105% were achieved. Results indicated the presence of two of the targeted COXIBs in real samples of sewage sludge, the highest average concentration (22ngg(-1)) corresponding to celecoxib. Moreover, the screening capabilities of the LC-QTOF-MS system demonstrated that the developed MSPD extraction procedure might be useful for the selective extraction of some other pharmaceuticals (e.g. amiodarone and their metabolite N-desethylamiodarone, miconazole, clotrimazole and ketoprofen) from sludge samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Prediction of mass transfer coefficients in non-Newtonian fermentation media using first-principles methods.

PubMed

Radl, Stefan; Khinast, Johannes G

2007-08-01

Bubble flows in non-Newtonian fluids were analyzed using first-principles methods with the aim to compute and predict mass transfer coefficients in such fermentation media. The method we used is a Direct Numerical Simulation (DNS) of the reactive multiphase flow with deformable boundaries and interfaces. With this method, we are able for the first time to calculate mass transfer coefficients in non-Newtonian liquids of different rheologies without any experimental data. In the current article, shear-thinning fluids are considered. However, the results provide the basis for further investigations, such as the study of viscoelastic fluids. (c) 2007 Wiley Periodicals, Inc.

Experimental research of solid waste drying in the process of thermal processing

NASA Astrophysics Data System (ADS)

Bukhmirov, V. V.; Kolibaba, O. B.; Gabitov, R. N.

2015-10-01

The convective drying process of municipal solid waste layer as a polydispersed multicomponent porous structure is studied. On the base of the experimental data criterial equations for calculating heat transfer and mass transfer processes in the layer, depending on the humidity of the material, the speed of the drying agent and the layer height are obtained. These solutions are used in the thermal design of reactors for the thermal processing of multicomponent organic waste.

The boundary integral theory for slow and rapid curved solid/liquid interfaces propagating into binary systems

NASA Astrophysics Data System (ADS)

Galenko, Peter K.; Alexandrov, Dmitri V.; Titova, Ekaterina A.

2018-01-01

The boundary integral method for propagating solid/liquid interfaces is detailed with allowance for the thermo-solutal Stefan-type models. Two types of mass transfer mechanisms corresponding to the local equilibrium (parabolic-type equation) and local non-equilibrium (hyperbolic-type equation) solidification conditions are considered. A unified integro-differential equation for the curved interface is derived. This equation contains the steady-state conditions of solidification as a special case. The boundary integral analysis demonstrates how to derive the quasi-stationary Ivantsov and Horvay-Cahn solutions that, respectively, define the paraboloidal and elliptical crystal shapes. In the limit of highest Péclet numbers, these quasi-stationary solutions describe the shape of the area around the dendritic tip in the form of a smooth sphere in the isotropic case and a deformed sphere along the directions of anisotropy strength in the anisotropic case. A thermo-solutal selection criterion of the quasi-stationary growth mode of dendrites which includes arbitrary Péclet numbers is obtained. To demonstrate the selection of patterns, computational modelling of the quasi-stationary growth of crystals in a binary mixture is carried out. The modelling makes it possible to obtain selected structures in the form of dendritic, fractal or planar crystals. This article is part of the theme issue `From atomistic interfaces to dendritic patterns'.

Low cost production of nematodes for biological control of insect pests

USDA-ARS?s Scientific Manuscript database

Entomopathogenic nematodes are produced in two ways: in artificial media using liquid or solid fermentation methods (in vitro) or by mass producing insect hosts to be artificially exposed to mass infection by nematodes (in vivo). The yellow mealworm (Tenebrio molitor) is a good host for in vivo nema...

Analytical prediction of forced convective heat transfer of fluids embedded with nanostructured materials (nanofluids)

NASA Astrophysics Data System (ADS)

Vasu, V.; Rama Krishna, K.; Kumar, A. C. S.

2007-09-01

Nanofluids are a new class of heat transfer fluids developed by suspending nanosized solid particles in liquids. Larger thermal conductivity of solid particles compared to the base fluid such as water, ethylene glycol, engine oil etc. significantly enhances their thermal properties. Several phenomenological models have been proposed to explain the anomalous heat transfer enhancement in nanofluids. This paper presents a systematic literature survey to exploit the characteristics of nanofluids, viz., thermal conductivity, specific heat and other thermal properties. An empirical correlation for the thermal conductivity of Al_{2}O_{3} + water and Cu + water nanofluids, considering the effects of temperature, volume fraction and size of the nanoparticle is developed and presented. A correlation for the evaluation of Nusselt number is also developed and presented and compared in graphical form. This enhanced thermophysical and heat transfer characteristics make fluids embedded with nanomaterials as excellent candidates for future applications.

Particle Fabrication Using Inkjet Printing onto Hydrophobic Surfaces for Optimization and Calibration of Trace Contraband Detection Sensors

PubMed Central

Gillen, Greg; Najarro, Marcela; Wight, Scott; Walker, Marlon; Verkouteren, Jennifer; Windsor, Eric; Barr, Tim; Staymates, Matthew; Urbas, Aaron

2015-01-01

A method has been developed to fabricate patterned arrays of micrometer-sized monodisperse solid particles of ammonium nitrate on hydrophobic silicon surfaces using inkjet printing. The method relies on dispensing one or more microdrops of a concentrated aqueous ammonium nitrate solution from a drop-on-demand (DOD) inkjet printer at specific locations on a silicon substrate rendered hydrophobic by a perfluorodecytrichlorosilane monolayer coating. The deposited liquid droplets form into the shape of a spherical shaped cap; during the evaporation process, a deposited liquid droplet maintains this geometry until it forms a solid micrometer sized particle. Arrays of solid particles are obtained by sequential translation of the printer stage. The use of DOD inkjet printing for fabrication of discrete particle arrays allows for precise control of particle characteristics (mass, diameter and height), as well as the particle number and spatial distribution on the substrate. The final mass of an individual particle is precisely determined by using gravimetric measurement of the average mass of solution ejected per microdrop. The primary application of this method is fabrication of test materials for the evaluation of spatially-resolved optical and mass spectrometry based sensors used for detecting particle residues of contraband materials, such as explosives or narcotics. PMID:26610515

Particle Fabrication Using Inkjet Printing onto Hydrophobic Surfaces for Optimization and Calibration of Trace Contraband Detection Sensors.

PubMed

Gillen, Greg; Najarro, Marcela; Wight, Scott; Walker, Marlon; Verkouteren, Jennifer; Windsor, Eric; Barr, Tim; Staymates, Matthew; Urbas, Aaron

2015-11-24

A method has been developed to fabricate patterned arrays of micrometer-sized monodisperse solid particles of ammonium nitrate on hydrophobic silicon surfaces using inkjet printing. The method relies on dispensing one or more microdrops of a concentrated aqueous ammonium nitrate solution from a drop-on-demand (DOD) inkjet printer at specific locations on a silicon substrate rendered hydrophobic by a perfluorodecytrichlorosilane monolayer coating. The deposited liquid droplets form into the shape of a spherical shaped cap; during the evaporation process, a deposited liquid droplet maintains this geometry until it forms a solid micrometer sized particle. Arrays of solid particles are obtained by sequential translation of the printer stage. The use of DOD inkjet printing for fabrication of discrete particle arrays allows for precise control of particle characteristics (mass, diameter and height), as well as the particle number and spatial distribution on the substrate. The final mass of an individual particle is precisely determined by using gravimetric measurement of the average mass of solution ejected per microdrop. The primary application of this method is fabrication of test materials for the evaluation of spatially-resolved optical and mass spectrometry based sensors used for detecting particle residues of contraband materials, such as explosives or narcotics.

The COLD-SAT Experiment for Cryogenic Fluid Management Technology

NASA Technical Reports Server (NTRS)

Schuster, J. R.; Wachter, J. P.; Vento, D. M.

1990-01-01

Future national space transportation missions will depend on the use of cryogenic fluid management technology development needs for these missions. In-space testing will be conducted in order to show low gravity cryogenic fluid management concepts and to acquire a technical data base. Liquid H2 is the preferred test fluid due to its propellant use. The design of COLD-SAT (Cryogenic On-orbit Liquid Depot Storage, Acquisition, and Transfer Satellite), an Expendable Launch Vehicle (ELV) launched orbital spacecraft that will perform subcritical liquid H2 storage and transfer experiments under low gravity conditions is studied. An Atlas launch vehicle will place COLD-SAT into a circular orbit, and the 3-axis controlled spacecraft bus will provide electric power, experiment control, and data management, attitude control, and propulsive accelerations for the experiments. Low levels of acceleration will provide data on the effects that low gravity might have on the heat and mass transfer processes used. The experiment module will contain 3 liquid H2 tanks; fluid transfer, pressurization and venting equipment; and instrumentation.

Determination of solid mass fraction in partially frozen hydrocarbon fuels

NASA Technical Reports Server (NTRS)

Cotterell, E. M.; Mossadegh, R.; Bruce, A. J.; Moynihan, C. T.

1986-01-01

Filtration procedures alone are insufficient to determine the amounts of crystalline solid in a partially frozen hydrocarbon distillate fraction. This is due to the nature of the solidification process by which a large amount of liquid becomes entrapped within an interconnected crystalline structure. A technique has been developed to supplement filtration methods with an independent determination of the amount of liquid in the precipitate thereby revealing the actual value of mass percent crystalline solid, %S. A non-crystallizing dye is injected into the fuel and used as a tracer during the filtration. The relative concentrations of the dye in the filtrate and precipitate fractions is subsequently detected by a spectrophotometric comparison. The filtration apparatus was assembled so that the temperature of the sample is recorded immediately above the filter. Also, a second method of calculation has been established which allows significant reduction in test time while retaining acceptable accuracy of results. Data have been obtained for eight different kerosene range hydrocarbon fuels.

Effect of immobile isolated enzymes from rumen liquid by using alginate matrices on the bay leaf extraction

NASA Astrophysics Data System (ADS)

Paramita, Vita; Yulianto, Mohammad Endy; Yohana, Eflita; Arifan, Fahmi; Hanifah, Amjad, Muhammad Taqiyuddin

2015-12-01

This research aims to develop the enzymatically of bay leaves phytochemical extraction process. The novelty and the main innovations of this research is the development of extraction process by using enzymatic extractor and isolate the enzymes from rumen liquid to shift the equilibrium phase, increase the extraction rate and increase the extraction yield. The activity of rumen liquid enzyme was represented by the activity of cellulase and protease. The analyze of total flavonoid content was performed by using UV-Vis Spectrofometry. The activity of immobilized enzyme of cellulase (0.08±0.00 U/ml) was lower than the un-immobilized one (0.23±0.00 U/ml). However, there was no difference activity of the immobilized (0.75±0.00 U/ml) and un-immobilized (0.76±0.01 U/ml) of protease. The model of mass transfer of un-immobilized enzyme can be fitted on the experimental data, however the model of mass transfer of immobilized enzyme did not match with the experimental data. The mass transfer coefficient of enzymatic extraction flavonoids bay leaf without immobilization was 0.17167 s-1 which greater than the reported value of obtained KLa from extraction by using electric heating.

Method for simultaneous measurement of mass loading and fluid property changes using a quartz crystal microbalance

DOEpatents

Granstaff, Victoria E.; Martin, Stephen J.

1993-01-01

A method, using a quartz crystal microbalance, to obtain simultaneous measurement of solid mass accumulation and changes in liquid density-viscosity product. The simultaneous real-time measurements of electrical parameters yields that changes in surface mass can be differentiated from changes in solution properties. Two methods to obtain the admittance/frequency data are employed.

Detection of positive and negative ions from a flowing atmospheric pressure afterglow using a Mattauch-Herzog mass spectrograph equipped with a Faraday-strip array detector.

PubMed

Schilling, Gregory D; Shelley, Jacob T; Barnes, James H; Sperline, Roger P; Denton, M Bonner; Barinaga, Charles J; Koppenaal, David W; Hieftje, Gary M

2010-01-01

An ambient desorption/ionization (ADI) source, known as the flowing atmospheric pressure afterglow (FAPA), has been coupled to a Mattauch-Herzog mass spectrograph (MHMS) equipped with a focal plane camera (FPC) array detector. The FAPA ionization source enables direct mass spectral analysis of solids, liquids, and gases through either positive or negative ionization modes. In either case, spectra are generally simple with dominant peaks being the molecular ions or protonated molecular ions. Use of the FAPA source with the MHMS allows the FPC detector to be characterized for the determination of molecular species, whereas previously only atomic mass spectrometry (MS) has been demonstrated. Furthermore, the FPC is shown to be sensitive to negative ions without the need to change any detector parameters. The analysis of solid, liquid, and gaseous samples through positive and negative ionization is demonstrated with detection limits (1-25 fmol/s, approximately 0.3-10 pg of analyte per mL of helium) surpassing those obtained with the FAPA source coupled to a time-of-flight mass analyzer. 2010 American Society for Mass Spectrometry. Published by Elsevier Inc. All rights reserved.

Adsorption of basic dyes on granular activated carbon and natural zeolite.

PubMed

Meshko, V; Markovska, L; Mincheva, M; Rodrigues, A E

2001-10-01

The adsorption of basic dyes from aqueous solution onto granular activated carbon and natural zeolite has been studied using an agitated batch adsorber. The influence of agitation, initial dye concentration and adsorbent mass has been studied. The parameters of Langmuir and Freundlich adsorption isotherms have been determined using the adsorption data. Homogeneous diffusion model (solid diffusion) combined with external mass transfer resistance is proposed for the kinetic investigation. The dependence of solid diffusion coefficient on initial concentration and mass adsorbent is represented by the simple empirical equations.

TERMINAL ELECTRON ACCEPTOR MASS BALANCE: LIGHT NONAQUEOUS PHASE LIQUIDS AND NATURAL ATTENUATION

EPA Science Inventory

Nonaqueous phase liquids (NAPLs) in subsurface systems contain a relatively large amount of biodegradable organic material. During the biochemical oxidation of the organic compounds in the NAPL, electrons are transferred to terminal electron acceptors (TEA) (i.e., O2, NO3-, Mn(I...

Effect of heat transfer of melt/solid interface shape and solute segregation in Edge-Defined Film-Fed growth - Finite element analysis

NASA Technical Reports Server (NTRS)

Ettouney, H. M.; Brown, R. A.

1982-01-01

The effects of the heat transfer environment in Edge-Defined Film-Fed Growth on melt-solid interface shape and lateral dopant segregation are studied by finite-element analysis of two-dimensional models for heat and mass transfer. Heat transfer configurations are studied that correspond to the uniform surroundings assumed in previous models and to lowand high-speed growth systems. The maximum growth rate for a silicon sheet is calculated and the range of validity of one-dimensional heat transfer models is established. The lateral segregation that results from curvature of the solidification interface is calculated for two solutes, boron and aluminum. In this way, heat transfer is linked directly to the uniformity of the product crystal.

In-situ biogas upgrading in thermophilic granular UASB reactor: key factors affecting the hydrogen mass transfer rate.

PubMed

Bassani, Ilaria; Kougias, Panagiotis G; Angelidaki, Irini

2016-12-01

Biological biogas upgrading coupling CO 2 with external H 2 to form biomethane opens new avenues for sustainable biofuel production. For developing this technology, efficient H 2 to liquid transfer is fundamental. This study proposes an innovative setup for in-situ biogas upgrading converting the CO 2 in the biogas into CH 4 , via hydrogenotrophic methanogenesis. The setup consisted of a granular reactor connected to a separate chamber, where H 2 was injected. Different packing materials (rashig rings and alumina ceramic sponge) were tested to increase gas-liquid mass transfer. This aspect was optimized by liquid and gas recirculation and chamber configuration. It was shown that by distributing H 2 through a metallic diffuser followed by ceramic sponge in a separate chamber, having a volume of 25% of the reactor, and by applying a mild gas recirculation, CO 2 content in the biogas dropped from 42 to 10% and the final biogas was upgraded from 58 to 82% CH 4 content. Copyright © 2016 Elsevier Ltd. All rights reserved.

Use of Generalized Fluid System Simulation Program (GFSSP) for Teaching and Performing Senior Design Projects at the Educational Institutions

NASA Technical Reports Server (NTRS)

Majumdar, A. K.; Hedayat, A.

2015-01-01

This paper describes the experience of the authors in using the Generalized Fluid System Simulation Program (GFSSP) in teaching Design of Thermal Systems class at University of Alabama in Huntsville. GFSSP is a finite volume based thermo-fluid system network analysis code, developed at NASA/Marshall Space Flight Center, and is extensively used in NASA, Department of Defense, and aerospace industries for propulsion system design, analysis, and performance evaluation. The educational version of GFSSP is freely available to all US higher education institutions. The main purpose of the paper is to illustrate the utilization of this user-friendly code for the thermal systems design and fluid engineering courses and to encourage the instructors to utilize the code for the class assignments as well as senior design projects. The need for a generalized computer program for thermofluid analysis in a flow network has been felt for a long time in aerospace industries. Designers of thermofluid systems often need to know pressures, temperatures, flow rates, concentrations, and heat transfer rates at different parts of a flow circuit for steady state or transient conditions. Such applications occur in propulsion systems for tank pressurization, internal flow analysis of rocket engine turbopumps, chilldown of cryogenic tanks and transfer lines, and many other applications of gas-liquid systems involving fluid transients and conjugate heat and mass transfer. Computer resource requirements to perform time-dependent, three-dimensional Navier-Stokes computational fluid dynamic (CFD) analysis of such systems are prohibitive and therefore are not practical. Available commercial codes are generally suitable for steady state, single-phase incompressible flow. Because of the proprietary nature of such codes, it is not possible to extend their capability to satisfy the above-mentioned needs. Therefore, the Generalized Fluid System Simulation Program (GFSSP1) has been developed at NASA Marshall Space Flight Center (MSFC) as a general fluid flow system solver capable of handling phase changes, compressibility, mixture thermodynamics and transient operations. It also includes the capability to model external body forces such as gravity and centrifugal effects in a complex flow network. The objectives of GFSSP development are: a) to develop a robust and efficient numerical algorithm to solve a system of equations describing a flow network containing phase changes, mixing, and rotation; and b) to implement the algorithm in a structured, easy-to-use computer program. The analysis of thermofluid dynamics in a complex network requires resolution of the system into fluid nodes and branches, and solid nodes and conductors as shown in Figure 1. Figure 1 shows a schematic and GFSSP flow circuit of a counter-flow heat exchanger. Hot nitrogen gas is flowing through a pipe, colder nitrogen is flowing counter to the hot stream in the annulus pipe and heat transfer occurs through metal tubes. The problem considered is to calculate flowrates and temperature distributions in both streams. GFSSP has a unique data structure, as shown in Figure 2, that allows constructing all possible arrangements of a flow network with no limit on the number of elements. The elements of a flow network are boundary nodes where pressure and temperature are specified, internal nodes where pressure and temperature are calculated, and branches where flowrates are calculated. For conjugate heat transfer problems, there are three additional elements: solid node, ambient node, and conductor. The solid and fluid nodes are connected with solid-fluid conductors. GFSSP solves the conservation equations of mass and energy, and equation of state in internal nodes to calculate pressure, temperature and resident mass. The momentum conservation equation is solved in branches to calculate flowrate. It also solves for energy conservation equations to calculate temperatures of solid nodes. The equations are coupled and nonlinear; therefore, they are solved by an iterative numerical scheme. GFSSP employs a unique numerical scheme known as simultaneous adjustment with successive substitution (SASS), which is a combination of Newton-Raphson and successive substitution methods. The mass and momentum conservation equations and the equation of state are solved by the Newton-Raphson method while the conservation of energy and species are solved by the successive substitution method. GFSSP is linked with two thermodynamic property programs, GASP2 and WASP3 and GASPAK4, that provide thermodynamic and thermophysical properties of selected fluids. Both programs cover a range of pressure and temperature that allows fluid properties to be evaluated for liquid, liquid-vapor (saturation), and vapor region. GASP and WASP provide properties of 12 fluids. GASPAK includes a library of 36 fluids. GFSSP has three major parts. The first part is the graphical user interface (GUI), visual thermofluid analyzer of systems and components (VTASC). VTASC allows users to create a flow circuit by a 'point and click' paradigm. It creates the GFSSP input file after the completion of the model building process. GFSSP's GUI provides the users a platform to build and run their models. It also allows post-processing of results. The network flow circuit is first built using three basic elements: boundary node, internal node, and branch.

Measurements of the Temperature-Dependent Total Hemispherical Emissivity Using an Electrostatic Levitation Facility

NASA Astrophysics Data System (ADS)

Gangopadhyay, A. K.; Kelton, K. F.

2017-01-01

Among the three fundamental processes of heat transfer (conduction, convection, and radiation), radiation is the most dominant at high temperatures. The total hemispherical emissivity is an important property that determines the amount of heat loss by radiation. Unfortunately, the emissivity, especially its temperature dependence (ɛ (T)), is unknown for most materials. Here, we demonstrate the feasibility of measuring ɛ (T) using an electrostatic levitation (ESL) technique that allows such measurements to be made on levitated solid and liquid samples in a contamination-free, high-vacuum environment. The ɛ (T) for solid Ni and liquid Zr_{60}Al_{10}Cu_{18}Ni9Co3 from these measurements is consistent with the existing literature data.

Electrification of particulate entrained fluid flows-Mechanisms, applications, and numerical methodology

NASA Astrophysics Data System (ADS)

Wei, Wei; Gu, Zhaolin

2015-10-01

Particulates in natural and industrial flows have two basic forms: liquid (droplet) and solid (particle). Droplets would be charged in the presence of the applied electric field (e.g. electrospray). Similar to the droplet charging, particles can also be charged under the external electric field (e.g. electrostatic precipitator), while in the absence of external electric field, tribo-electrostatic charging is almost unavoidable in gas-solid two-phase flows due to the consecutive particle contacts (e.g. electrostatic in fluidized bed or wind-blown sand). The particle charging may be beneficial, or detrimental. Although electrostatics in particulate entrained fluid flow systems have been so widely used and concerned, the mechanisms of particulate charging are still lack of a thorough understanding. The motivation of this review is to explore a clear understanding of particulate charging and movement of charged particulate in two-phase flows, by summarizing the electrification mechanisms, physical models of particulate charging, and methods of charging/charged particulate entrained fluid flow simulations. Two effective methods can make droplets charged in industrial applications: corona charging and induction charging. The droplet charge to mass ratio by corona charging is more than induction discharge. The particle charging through collisions could be attributed to electron transfer, ion transfer, material transfer, and/or aqueous ion shift on particle surfaces. The charges on charged particulate surface can be measured, nevertheless, the charging process in nature or industry is difficult to monitor. The simulation method might build a bridge of investigating from the charging process to finally charged state on particulate surface in particulate entrained fluid flows. The methodology combining the interface tracking under the action of the applied electric with the fluid flow governing equations is applicable to the study of electrohydrodynamics problems. The charge distribution and mechanical behaviors of liquid surface can be predicted by using this method. The methodology combining particle charging model with Computational Fluid Dynamics (CFD) and Discrete element method (DEM) is applicable to study the particle charging/charged processes in gas-solid two phase flows, the influence factors of particle charging, such as gas-particle interaction, contact force, contact area, and various velocities, are described systematically. This review would explore a clear understanding of the particulate charging and provide theoretical references to control and utilize the charging/charged particulate entrained fluid system.

Improvement of mass transfer characteristics and productivities of inclined tubular photobioreactors by installation of internal static mixers.

PubMed

Ugwu, C U; Ogbonna, J C; Tanaka, H

2002-04-01

The feasibility of improving mass transfer characteristics of inclined tubular photobioreactors by installation of static mixers was investigated. The mass transfer characteristics of the tubular photobioreactor varied depending on the type (shape) and the number of static mixers. The volumetric oxygen transfer coefficient ( k(L)a) and gas hold up of the photobioreactor with internal static mixers were significantly higher than those of the photobioreactor without static mixers. The k(L)a and gas hold up increased with the number of static mixers but the mixing time became longer due to restricted liquid flow through the static mixers. By installing the static mixers, the liquid flow changed from plug flow to turbulent mixing so that cells were moved between the surface and bottom of the photobioreactor. In outdoor culture of Chlorella sorokiniana, the photobioreactor with static mixers gave higher biomass productivities irrespective of the standing biomass concentration and solar radiation. The effectiveness of the static mixers (average percentage increase in the productivities of the photobioreactor with static mixers over the productivities obtained without static mixers) was higher at higher standing biomass concentrations and on cloudy days (solar radiation below 6 MJ m(-2) day(-1)).

Pharmacokinetic Studies of Chinese Medicinal Herbs Using an Automated Blood Sampling System and Liquid Chromatography-mass Spectrometry.

PubMed

Wu, Yu-Tse; Wu, Ming-Tsang; Lin, Chia-Chun; Chien, Chao-Feng; Tsai, Tung-Hu

2012-01-01

The safety of herbal products is one of the major concerns for the modernization of traditional Chinese medicine, and pharmacokinetic data of medicinal herbs guide us to design the rational use of the herbal formula. This article reviews the advantages of the automated blood sampling (ABS) systems for pharmacokinetic studies. In addition, three commonly used sample preparative methods, protein precipitation, liquid-liquid extraction and solid-phase extraction, are introduced. Furthermore, the definition, causes and evaluation of matrix effects in liquid chromatography-mass spectrometry (LC/MS) analysis are demonstrated. Finally, we present our previous works as practical examples of the application of ABS systems and LC/MS for the pharmacokinetic studies of Chinese medicinal herbs.

Using liquid waste streams as the moisture source during the hydrothermal carbonization of municipal solid wastes.

PubMed

Li, Liang; Hale, McKenzie; Olsen, Petra; Berge, Nicole D

2014-11-01

Hydrothermal carbonization (HTC) is a thermal conversion process that can be an environmentally beneficial approach for the conversion of municipal solid wastes to value-added products. The influence of using activated sludge and landfill leachate as initial moisture sources during the carbonization of paper, food waste and yard waste over time at 250°C was evaluated. Results from batch experiments indicate that the use of activated sludge and landfill leachate are acceptable alternative supplemental liquid sources, ultimately imparting minimal impact on carbonization product characteristics and yields. Regression results indicate that the initial carbon content of the feedstock is more influential than any of the characteristics of the initial liquid source and is statistically significant when describing the relationship associated with all evaluated carbonization products. Initial liquid-phase characteristics are only statistically significant when describing the solids energy content and the mass of carbon in the gas-phase. The use of these alternative liquid sources has the potential to greatly increase the sustainability of the carbonization process. A life cycle assessment is required to quantify the benefits associated with using these alternative liquid sources. Copyright © 2014 Elsevier Ltd. All rights reserved.

Method development for liquid chromatographic/triple quadrupole mass spectrometric analysis of trace level perfluorocarboxylic acids in articles of commerce

EPA Science Inventory

An analytical method to identify and quantify trace levels of C5 to C12 perfluorocarboxylic acids (PFCAs) in articles of commerce (AOC) is developed and rigorously validated. Solid samples were extracted in methanol, and liquid samples were diluted with a solvent consisting of 60...

Influence of everyday bolus consistencies in different body positions on high-resolution esophageal pressure topography (HREPT) parameters.

PubMed

Hasan, Y; Go, J; Hashmi, S M; Valestin, J; Schey, R

2015-04-01

The standard protocol for esophageal manometry involves placing the patient in the supine position with head turned to left (supine head left [SHL]) while evaluating liquid bolus swallows. Routinely, semisolid or solid boluses are not evaluated. Currently, the daily American diet includes up to 40% solid or semisolid texture. Thus far, the data on the effect of different bolus on high-resolution esophageal pressure topography (HREPT) parameters are scarce. This study aims to evaluate the effect of every day bolus consistencies in different body positions on HREPT variables. HREPT was performed on healthy volunteers with a modified protocol including liquid swallows in the SHL position followed by applesauce (semisolid), cracker (solid), and marshmallow (soft solid) in three different positions (SHL, sitting, and standing). A total of 38 healthy adult subjects (22 males and 16 females, median age = 27, and mean body mass index = 25) were evaluated. The resting upper esophageal sphincter pressure was significantly different while subjects swallowed crackers, applesauce, and marshmallows in most positions compared with liquid SHL (P < 0.05). The lower esophageal sphincter, contractile front velocity, and distal contractile integral pressures did not differ in all different consistencies compared with SHL. The integrated relaxation period was significantly higher with solid bolus compared with liquid bolus only in SHL position. The intrabolus pressure was significantly different with solid and soft solid boluses in all postures compared to liquid SHL. The American diet consistency affects upper esophageal sphincter pressure and partially integrated relaxation period and intrabolus pressure in various positions. Semisolid bolus swallows do not cause substantial pressure changes and are safe for evaluation and maintaining adequate caloric intake in patients with dysphagia who cannot tolerate solids. © 2014 International Society for Diseases of the Esophagus.

Chiral Nematic Structure of Cellulose Nanocrystal Suspensions and Films; Polarized Light and Atomic Force Microscopy

PubMed Central

Gray, Derek G.; Mu, Xiaoyue

2015-01-01

Cellulosic liquid crystalline solutions and suspensions form chiral nematic phases that show a rich variety of optical textures in the liquid crystalline state. These ordered structures may be preserved in solid films prepared by evaporation of solvent or suspending medium. Film formation from aqueous suspensions of cellulose nanocrystals (CNC) was investigated by polarized light microscopy, optical profilometry and atomic force microscopy (AFM). An attempt is made to interpret qualitatively the observed textures in terms of the orientation of the cellulose nanocrystals in the suspensions and films, and the changes in orientation caused by the evaporative process. Mass transfer within the evaporating droplet resulted in the formation of raised rings whose magnitude depended on the degree of pinning of the receding contact line. AFM of dry films at short length scales showed a radial orientation of the CNC at the free surface of the film, along with a radial height variation with a period of approximately P/2, ascribed to the anisotropic shrinkage of the chiral nematic structure. PMID:28793684

49 CFR 172.322 - Marine pollutants.

Code of Federal Regulations, 2011 CFR

2011-10-01

... freight container or portable tank loaded on a motor vehicle or rail car. This mark may be displayed in... L (1.3 gallons) or less for liquids; or (ii) A net mass of 5 kg (11 pounds) or less for solids (2...) 5 kg (11 pounds) or less net capacity for solids. (3) Except for transportation by vessel, on a bulk...

49 CFR 172.322 - Marine pollutants.

Code of Federal Regulations, 2013 CFR

2013-10-01

... freight container or portable tank loaded on a motor vehicle or rail car. This mark may be displayed in... L (1.3 gallons) or less for liquids; or (ii) A net mass of 5 kg (11 pounds) or less for solids (2...) 5 kg (11 pounds) or less net capacity for solids. (3) Except for transportation by vessel, on a bulk...

Enhanced high-solids anaerobic digestion of waste activated sludge by the addition of scrap iron.

PubMed

Zhang, Yaobin; Feng, Yinghong; Yu, Qilin; Xu, Zibin; Quan, Xie

2014-05-01

Anaerobic digestion of waste activated sludge usually requires pretreatment procedure to improve the bioavailability of sludge, which involves considerable energy and high expenditures. This study proposes a cost-effective method for enhanced anaerobic digestion of sludge without a pretreatment by directly adding iron into the digester. The results showed that addition of Fe(0) powder could enhance 14.46% methane yield, and Fe scrap (clean scrap) could further enhance methane yield (improving rate 21.28%) because the scrap has better mass transfer efficiency with sludge and liquid than Fe(0) powder. The scrap of Fe with rust (rusty scrap) could induce microbial Fe(III) reduction, which resulted in achieving the highest methane yield (improving rate 29.51%), and the reduction rate of volatile suspended solids (VSS) was also highest (48.27%) among Fe powder, clean scrap and rusty scrap. PCR-DGGE proved that the addition of rusty scrap could enhance diversity of acetobacteria and enrich iron-reducing bacteria to enhance degradation of complex substrates. Copyright © 2014 Elsevier Ltd. All rights reserved.

Numerical Modelling of Staged Combustion Aft-Injected Hybrid Rocket Motors

NASA Astrophysics Data System (ADS)

Nijsse, Jeff

The staged combustion aft-injected hybrid (SCAIH) rocket motor is a promising design for the future of hybrid rocket propulsion. Advances in computational fluid dynamics and scientific computing have made computational modelling an effective tool in hybrid rocket motor design and development. The focus of this thesis is the numerical modelling of the SCAIH rocket motor in a turbulent combustion, high-speed, reactive flow framework accounting for solid soot transport and radiative heat transfer. The SCAIH motor is modelled with a shear coaxial injector with liquid oxygen injected in the center at sub-critical conditions: 150 K and 150 m/s (Mach ≈ 0.9), and a gas-generator gas-solid mixture of one-third carbon soot by mass injected in the annual opening at 1175 K and 460 m/s (Mach ≈ 0.6). Flow conditions in the near injector region and the flame anchoring mechanism are of particular interest. Overall, the flow is shown to exhibit instabilities and the flame is shown to anchor directly on the injector faceplate with temperatures in excess of 2700 K.

A critical review on liquid-gas mass transfer models for estimating gaseous emissions from passive liquid surfaces in wastewater treatment plants.

PubMed

Prata, Ademir A; Santos, Jane M; Timchenko, Victoria; Stuetz, Richard M

2018-03-01

Emission models are useful tools for the study and management of atmospheric emissions from passive liquid surfaces in wastewater treatment plants (WWTPs), which are potential sources of odour nuisance and other environmental impacts. In this work, different theoretical and empirical models for the gas-side (k G ) and liquid-side (k L ) mass transfer coefficients in passive surfaces in WWTPs were critically reviewed and evaluated against experimental data. Wind forcing and the development of the wind-wave field, especially the occurrence of microscale wave breaking, were identified as the most important physical factors affecting mass transfer in these situations. Two approaches performed well in describing the available data for k G for water vapour. One is an empirical correlation whilst the other consists of theoretical models based on the description of the inner part of the turbulent boundary layer over a smooth flat plate. We also fit to the experimental data set a new, alternate equation for k G , whose performance was comparable to existing ones. However, these three approaches do not agree with each other in the whole range of Schmidt numbers typical for compounds found in emissions from WWTPs. As to k L , no model was able to satisfactorily explain the behaviour and the scatter observed in the whole experimental data set. Excluding two suspected biased sources, the WATER9 (US EPA, 1994. Air Emission Models for Waste and Wastewater. North Carolina, USA. EPA-453/R-94-080A) approach produced the best results among the most commonly used k L models, although still with considerably high relative errors. For this same sub-set, we propose a new, alternate approach for estimating k L , which resulted in improved performance, particularly for longer fetches. Two main gaps were found in the literature, the understanding of the evolution of the mass transfer boundary layer over liquid surfaces, and the behaviour of k L for larger fetches, especially in the range from 40 to 60 m. Copyright © 2017 Elsevier Ltd. All rights reserved.

Rare earth element variations resulting from inversion of pigeonite and subsolidus reequilibration in lunar ferroan anorthosites

USGS Publications Warehouse

James, O.B.; Floss, C.; McGee, J.J.

2002-01-01

We present results of a secondary ion mass spectrometry study of the rare earth elements (REEs) in the minerals of two samples of lunar ferroan anorthosite, and the results are applicable to studies of REEs in all igneous rocks, no matter what their planet of origin. Our pyroxene analyses are used to determine solid-solid REE distribution coefficients (D = CREE in low-Ca pyroxene/CREE in augite) in orthopyroxene-augite pairs derived by inversion of pigeonite. Our data and predictions from crystal-chemical considerations indicate that as primary pigeonite inverts to orthopyroxene plus augite and subsolidus reequilibration proceeds, the solid-solid Ds for orthopyroxene-augite pairs progressively decrease for all REEs; the decrease is greatest for the LREEs. The REE pattern of solid-solid Ds for inversion-derived pyroxene pairs is close to a straight line for Sm-Lu and turns upward for REEs lighter than Sm; the shape of this pattern is predicted by the shapes of the REE patterns for the individual minerals. Equilibrium liquids calculated for one sample from the compositions of primary phases, using measured or experimentally determined solid-liquid Ds, have chondrite-normalized REE patterns that are very slightly enriched in LREEs. The plagioclase equilibrium liquid is overall less rich in REEs than pyroxene equilibrium liquids, and the discrepancy probably arises because the calculated plagioclase equilibrium liquid represents a liquid earlier in the fractionation sequence than the pyroxene equilibrium liquids. "Equilibrium" liquids calculated from the compositions of inversion-derived pyroxenes or orthopyroxene derived by reaction of olivine are LREE depleted (in some cases substantially) in comparison with equilibrium liquids calculated from the compositions of primary phases. These discrepancies arise because the inversion-derived and reaction-derived pyroxenes did not crystallize directly from liquid, and the use of solid-liquid Ds is inappropriate. The LREE depletion of the calculated liquids is a relic of formation of these phases from primary LREE-depleted minerals. Thus, if one attempts to calculate the compositions of equilibrium liquids from pyroxene compositions, it is important to establish that the pyroxenes are primary. In addition, our data suggest that experimental studies have underestimated solid-liquid Ds for REEs in pigeonite and that REE contents of liquids calculated using these Ds are overestimates. Our results have implications for Sm-Nd age studies. Our work shows that if pigeonite inversion and/or subsolidus reequilibration between augite and orthopyroxene occured significantly after crystallization, and if pyroxene separates isolated for Sm-Nd studies do not have the bulk composition of the primary pyroxenes, then the Sm-Nd isochron age and ??Nd will be in error. Copyright ?? 2002 Elsevier Science Ltd.

Parametric Thermal and Flow Analysis of ITER Diagnostic Shield Module

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khodak, A.; Zhai, Y.; Wang, W.

As part of the diagnostic port plug assembly, the ITER Diagnostic Shield Module (DSM) is designed to provide mechanical support and the plasma shielding while allowing access to plasma diagnostics. Thermal and hydraulic analysis of the DSM was performed using a conjugate heat transfer approach, in which heat transfer was resolved in both solid and liquid parts, and simultaneously, fluid dynamics analysis was performed only in the liquid part. ITER Diagnostic First Wall (DFW) and cooling tubing were also included in the analysis. This allowed direct modeling of the interface between DSM and DFW, and also direct assessment of themore » coolant flow distribution between the parts of DSM and DFW to ensure DSM design meets the DFW cooling requirements. Design of the DSM included voids filled with Boron Carbide pellets, allowing weight reduction while keeping shielding capability of the DSM. These voids were modeled as a continuous solid with smeared material properties using analytical relation for thermal conductivity. Results of the analysis lead to design modifications improving heat transfer efficiency of the DSM. Furthermore, the effect of design modifications on thermal performance as well as effect of Boron Carbide will be presented.« less

Parametric Thermal and Flow Analysis of ITER Diagnostic Shield Module

DOE PAGES

Khodak, A.; Zhai, Y.; Wang, W.; ...

2017-06-19

As part of the diagnostic port plug assembly, the ITER Diagnostic Shield Module (DSM) is designed to provide mechanical support and the plasma shielding while allowing access to plasma diagnostics. Thermal and hydraulic analysis of the DSM was performed using a conjugate heat transfer approach, in which heat transfer was resolved in both solid and liquid parts, and simultaneously, fluid dynamics analysis was performed only in the liquid part. ITER Diagnostic First Wall (DFW) and cooling tubing were also included in the analysis. This allowed direct modeling of the interface between DSM and DFW, and also direct assessment of themore » coolant flow distribution between the parts of DSM and DFW to ensure DSM design meets the DFW cooling requirements. Design of the DSM included voids filled with Boron Carbide pellets, allowing weight reduction while keeping shielding capability of the DSM. These voids were modeled as a continuous solid with smeared material properties using analytical relation for thermal conductivity. Results of the analysis lead to design modifications improving heat transfer efficiency of the DSM. Furthermore, the effect of design modifications on thermal performance as well as effect of Boron Carbide will be presented.« less

Evaporation kinetics of sessile water droplets on micropillared superhydrophobic surfaces.

PubMed

Xu, Wei; Leeladhar, Rajesh; Kang, Yong Tae; Choi, Chang-Hwan

2013-05-21

Evaporation modes and kinetics of sessile droplets of water on micropillared superhydrophobic surfaces are experimentally investigated. The results show that a constant contact radius (CCR) mode and a constant contact angle (CCA) mode are two dominating evaporation modes during droplet evaporation on the superhydrophobic surfaces. With the decrease in the solid fraction of the superhydrophobic surfaces, the duration of a CCR mode is reduced and that of a CCA mode is increased. Compared to Rowan's kinetic model, which is based on the vapor diffusion across the droplet boundary, the change in a contact angle in a CCR (pinned) mode shows a remarkable deviation, decreasing at a slower rate on the superhydrophobic surfaces with less-solid fractions. In a CCA (receding) mode, the change in a contact radius agrees well with the theoretical expectation, and the receding speed is slower on the superhydrophobic surfaces with lower solid fractions. The discrepancy between experimental results and Rowan's model is attributed to the initial large contact angle of a droplet on superhydrophobic surfaces. The droplet geometry with a large contact angle results in a narrow wedge region of air along the contact boundary, where the liquid-vapor diffusion is significantly restricted. Such an effect becomes minor as the evaporation proceeds with the decrease in a contact angle. In both the CCR and CCA modes, the evaporative mass transfer shows the linear relationship between mass(2/3) and evaporation time. However, the evaporation rate is slower on the superhydrophobic surfaces, which is more significant on the surfaces with lower solid fractions. As a result, the superhydrophobic surfaces slow down the drying process of a sessile droplet on them.

Carbon monoxide mass transfer for syngas fermentation in a stirred tank reactor with dual impeller configurations.

PubMed

Ungerman, Andrew J; Heindel, Theodore J

2007-01-01

This study compares the power demand and gas-liquid volumetric mass transfer coefficient, kLa, in a stirred tank reactor (STR) (T = 0.211 m) using different impeller designs and schemes in a carbon monoxide-water system, which is applicable to synthesis gas (syngas) fermentation. Eleven different impeller schemes were tested over a range of operating conditions typically associated with the "after large cavity" region (ALC) of a Rushton-type turbine (D/T = 0.35). It is found that the dual Rushton-type impeller scheme exhibits the highest volumetric mass transfer rates for all operating conditions; however, it also displays the lowest mass transfer performance (defined as the volumetric mass transfer coefficient per unit power input) for all conditions due to its high power consumption. Dual impeller schemes with an axial flow impeller as the top impeller show improved mass transfer rates without dramatic increases in power draw. At high gas flow rates, dual impeller schemes with a lower concave impeller have kLa values similar to those of the Rushton-type dual impeller schemes but show improved mass transfer performance. It is believed that the mass transfer performance can be further enhanced for the bottom concave impeller schemes by operating at conditions beyond the ALC region defined for Rushton-type impellers because the concave impeller can handle higher gas flow rates prior to flooding.

Comparative evaluation of liquid-liquid extraction, solid-phase extraction and solid-phase microextraction for the gas chromatography-mass spectrometry determination of multiclass priority organic contaminants in wastewater.

PubMed

Robles-Molina, José; Gilbert-López, Bienvenida; García-Reyes, Juan F; Molina-Díaz, Antonio

2013-12-15

The European Water Framework Directive (WFD) 2000/60/EC establishes guidelines to control the pollution of surface water by sorting out a list of priority substances that involves a significant risk to or via the aquatic systems. In this article, the analytical performance of three different sample preparation methodologies for the GC-MS/MS determination of multiclass organic contaminants-including priority comprounds from the WFD-in wastewater samples using gas chromatography-mass spectrometry was evaluated. The methodologies tested were: (a) liquid-liquid extraction (LLE) with n-hexane; (b) solid-phase extraction (SPE) with C18 cartridges and elution with ethyl acetate:dichloromethane (1:1 (v/v)), and (c) headspace solid-phase microextraction (HS-SPME) using two different fibers: polyacrylate and polydimethylsiloxane/carboxen/divinilbenzene. Identification and confirmation of the selected 57 compounds included in the study (comprising polycyclic aromatic hydrocarbons (PAHs), pesticides and other contaminants) were accomplished using gas chromatography tandem mass spectrometry (GC-MS/MS) with a triple quadrupole instrument operated in the multiple reaction monitoring (MRM) mode. Three MS/MS transitions were selected for unambiguous confirmation of the target chemicals. The different advantages and pitfalls of each method were discussed. In the case of both LLE and SPE procedures, the method was validated at two different concentration levels (15 and 150 ng L(-1)) obtaining recovery rates in the range 70-120% for most of the target compounds. In terms of analyte coverage, results with HS-SPME were not satisfactory, since 14 of the compounds tested were not properly recovered and the overall performance was worse than the other two methods tested. LLE, SPE and HS-SPME (using polyacrylate fiber) procedures also showed good linearity and precision. Using any of the three methodologies tested, limits of quantitation obtained for most of the detected compounds were in the low nanogram per liter range. © 2013 Elsevier B.V. All rights reserved.

Application of binomial-edited CPMG to shale characterization

USGS Publications Warehouse

Washburn, Kathryn E.; Birdwell, Justin E.

2014-01-01

Unconventional shale resources may contain a significant amount of hydrogen in organic solids such as kerogen, but it is not possible to directly detect these solids with many NMR systems. Binomial-edited pulse sequences capitalize on magnetization transfer between solids, semi-solids, and liquids to provide an indirect method of detecting solid organic materials in shales. When the organic solids can be directly measured, binomial-editing helps distinguish between different phases. We applied a binomial-edited CPMG pulse sequence to a range of natural and experimentally-altered shale samples. The most substantial signal loss is seen in shales rich in organic solids while fluids associated with inorganic pores seem essentially unaffected. This suggests that binomial-editing is a potential method for determining fluid locations, solid organic content, and kerogen–bitumen discrimination.

A self-forming composite electrolyte for solid-state sodium battery with ultra-long cycle life

DOE PAGES

Zhang, Zhizhen; Yang, Xiao -Qing; Zhang, Qinghua; ...

2016-10-31

Replacing organic liquid electrolyte with inorganic solid electrolytes (SE) can potentially address the inherent safety problems in conventional rechargeable batteries. Furthermore, all-solid-state batteries have been plagues by the relatively low ionic conductivity of solid electrolytes and large charge-transfer resistance resulted from solid-solid interfaces between electrode materials and solid electrolytes. Here we report a new design strategy for improving the ionic conductivity of solid electrolyte by self-forming a composite material. An optimized Na + ion conducting composite electrolyte derived from the NASICON structure was successfully synthesized, yielding ultra-high ionic conductivity of 3.4 mS cm –1 at 25°C and 14 ms cmmore » –1 at 80°C.« less

Investigations of effect of phase change mass transfer rate on cavitation process with homogeneous relaxation model

DOE Office of Scientific and Technical Information (OSTI.GOV)

He, Zhixia; Zhang, Liang; Saha, Kaushik

The super high fuel injection pressure and micro size of nozzle orifice has been an important development trend for the fuel injection system. Accordingly, cavitation transient process, fuel compressibility, amount of noncondensable gas in the fuel and cavitation erosion have attracted more attention. Based on the fact of cavitation in itself is a kind of thermodynamic phase change process, this paper takes the perspective of the cavitation phase change mass transfer process to analyze above mentioned phenomenon. The two-phase cavitating turbulent flow simulations with VOF approach coupled with HRM cavitation model and U-RANS of standard k-ε turbulence model were performedmore » for investigations of cavitation phase change mass transfer process. It is concluded the mass transfer time scale coefficient in the Homogenous Relaxation Model (HRM) representing mass transfer rate should tend to be as small as possible in a condition that ensured the solver stable. At very fast mass transfer rate, the phase change occurs at very thin interface between liquid and vapor phase and condensation occurs more focused and then will contribute predictably to a more serious cavitation erosion. Both the initial non-condensable gas in fuel and the fuel compressibility can accelerate the cavitation mass transfer process.« less

Modeling for free surface flow with phase change and its application to fusion technology

NASA Astrophysics Data System (ADS)

Luo, Xiaoyong

The development of predictive capabilities for free surface flow with phase change is essential to evaluate liquid wall protection schemes for various fusion chambers. With inertial fusion energy (IFE) concepts such as HYLIFE-II, rapid condensation into cold liquid surfaces is required when using liquid curtains for protecting reactor walls from blasts and intense neutron radiation. With magnetic fusion energy (MFE) concepts, droplets are injected onto the free surface of the liquid to minimize evaporation by minimizing the surface temperature. This dissertation presents a numerical methodology for free surface flow with phase change to help resolve feasibility issues encountered in the aforementioned fusion engineering fields, especially spray droplet condensation efficiency in IFE and droplet heat transfer enhancement on free surface liquid divertors in MFE. The numerical methodology is being conducted within the framework of the incompressible flow with the phase change model. A new second-order projection method is presented in conjunction with Approximate-Factorization techniques (AF method) for incompressible Navier-Stokes equations. A sub-cell conception is introduced and the Ghost Fluid Method in extended in a modified mass transfer model to accurately calculate the mass transfer across the interface. The Crank-Nicholson method is used for the diffusion term to eliminate the numerical viscous stability restriction. The third-order ENO scheme is used for the convective term to guarantee the accuracy of the method. The level set method is used to capture accurately the free surface of the flow and the deformation of the droplets. This numerical investigation identifies the physics characterizing transient heat and mass transfer of the droplet and the free surface flow. The results show that the numerical methodology is quite successful in modeling the free surface with phase change even though some severe deformations such as breaking and merging occur. The versatility of the numerical methodology shows that the work can easily handle complex physical conditions that occur in the fusion science and engineering.

A frequency quantum interpretation of the surface renewal model of mass transfer

PubMed Central

Mondal, Chanchal

2017-01-01

The surface of a turbulent liquid is visualized as consisting of a large number of chaotic eddies or liquid elements. Assuming that surface elements of a particular age have renewal frequencies that are integral multiples of a fundamental frequency quantum, and further assuming that the renewal frequency distribution is of the Boltzmann type, performing a population balance for these elements leads to the Danckwerts surface age distribution. The basic quantum is what has been traditionally called the rate of surface renewal. The Higbie surface age distribution follows if the renewal frequency distribution of such elements is assumed to be continuous. Four age distributions, which reflect different start-up conditions of the absorption process, are then used to analyse transient physical gas absorption into a large volume of liquid, assuming negligible gas-side mass-transfer resistance. The first two are different versions of the Danckwerts model, the third one is based on the uniform and Higbie distributions, while the fourth one is a mixed distribution. For the four cases, theoretical expressions are derived for the rates of gas absorption and dissolved-gas transfer to the bulk liquid. Under transient conditions, these two rates are not equal and have an inverse relationship. However, with the progress of absorption towards steady state, they approach one another. Assuming steady-state conditions, the conventional one-parameter Danckwerts age distribution is generalized to a two-parameter age distribution. Like the two-parameter logarithmic normal distribution, this distribution can also capture the bell-shaped nature of the distribution of the ages of surface elements observed experimentally in air–sea gas and heat exchange. Estimates of the liquid-side mass-transfer coefficient made using these two distributions for the absorption of hydrogen and oxygen in water are very close to one another and are comparable to experimental values reported in the literature. PMID:28791137

Finding the chemistry in biomass pyrolysis: Millisecond chemical kinetics and visualization

NASA Astrophysics Data System (ADS)

Krumm, Christoph

Biomass pyrolysis is a promising thermochemical method for producing fuels and chemicals from renewable sources. Development of a fundamental understanding of biomass pyrolysis chemistry is difficult due to the multi-scale and multi-phase nature of the process; biomass length scales span 11 orders of magnitude and pyrolysis phenomena include solid, liquid, and gas phase chemistry in addition to heat and mass transfer. These complexities have a significant effect on chemical product distributions and lead to variability between reactor technologies. A major challenge in the study of biomass pyrolysis is the development of kinetic models capable of describing hundreds of millisecond-scale reactions of biomass into lower molecular weight products. In this work, a novel technique for studying biomass pyrolysis provides the first- ever experimental determination of kinetics and rates of formation of the primary products from cellulose pyrolysis, providing insight into the millisecond-scale chemical reaction mechanisms. These findings highlight the importance of heat and mass transport limitations for cellulose pyrolysis chemistry and are used to identify the length scales at which transport limitations become relevant during pyrolysis. Through this technique, a transition is identified, known as the reactive melting point, between low and high temperature depolymerization. The transition between two mechanisms of cellulose decompositions unifies the mechanisms that govern low temperature char formation, intermediate pyrolysis conditions, and high temperature gas formation. The conditions under which biomass undergoes pyrolysis, including modes of heat transfer, have been shown to significantly affect the distribution of biorenewable chemical and fuel products. High-speed photography is used to observe the liftoff of initially crystalline cellulose particles when impinged on a heated surface, known as the Leidenfrost effect for room-temperature liquids. Order-of-magnitude changes in the lifetime of cellulose particles are observed as a result of changing modes in heat transfer as cellulose intermediate liquid droplets wet and de-wet polished ceramic surfaces. Introduction of surface macroporosity is shown to completely inhibit the cellulose Leidenfrost effect, providing avenues for surface modification and reactor design to control particle heat transfer in industrial pyrolysis applications. Cellulosic particles on surfaces consisting of microstructured, asymmetric ratchets were observed to spontaneously move orthogonal to ratchet wells above the cellulose reactive Leidenfrost temperature (>750 °C). Evaluation of the accelerating particles supported the mechanism of propelling viscous forces (50-200 nN) from rectified pyrolysis vapors, thus providing the first example of biomass conveyors with no moving parts driven by high temperature for biofuel reactors. Combined knowledge of pyrolysis chemistry, kinetics, and heat and mass transport effects direct the design of the next generation pyrolysis reactors for tuning bio- oil quality and design of improved catalytic upgrading technology.

Ultra-high-pressure liquid chromatography-tandem mass spectrometry method for the determination of alkylphenols in soil.

PubMed

Wang, Jing; Pan, Hefang; Liu, Zhengzheng; Ge, Fei

2009-03-20

A novel method has been developed for the determination of alkylphenols in soil by ultra-high-pressure liquid chromatography employing small particle sizes, combined with tandem mass spectrometry. Soil samples were extracted with pressurized liquid extraction (PLE) and then cleaned with solid-phase extraction (SPE). The extracts were separated on C18 column (1.7 microm, 50 mm x 2.1mm) with a gradient elution and a mobile phase consisting of water and acetonitrile, and then detected by an electrospray ionization tandem mass spectrometry in negative ion mode with multiple reaction monitoring (MRM). Compared with traditional liquid chromatography, it took ultra-high-pressure liquid chromatography much less time to analyze alkylphenols. Additionally, the ultra-high-pressure liquid chromatography/tandem mass spectrometry method produces satisfactory reliability, sensitivity, and accuracy. The average recoveries of the three target analytes were 74.0-103.4%, with the RSD<15%. The calibration curves for alkylphenols were linear within the range of 0.01-0.4 microg/ml, with the correlation coefficients greater than 0.99. When 10 g soil sample was used for analysis, the limits of quantification (LOQs) of the three alkylphenols were all 1.0 microg/kg.

Liquid-solid surface phase transformation of fluorinated fullerene on monolayer tungsten diselenide

NASA Astrophysics Data System (ADS)

Song, Zhibo; Wang, Qixing; Li, Ming-Yang; Li, Lain-Jong; Zheng, Yu Jie; Wang, Zhuo; Lin, Tingting; Chi, Dongzhi; Ding, Zijing; Huang, Yu Li; Thye Shen Wee, Andrew

2018-04-01

Hybrid van der Waals heterostructures constructed by the integration of organic molecules and two-dimensional (2D) transition metal dichalcogenide (TMD) materials have useful tunable properties for flexible electronic devices. Due to the chemically inert and atomically smooth nature of the TMD surface, well-defined crystalline organic films form atomically sharp interfaces facilitating optimal device performance. Here, the surface phase transformation of the supramolecular packing structure of fluorinated fullerene (C60F48 ) on single-layer tungsten diselenide (WSe2) is revealed by low-temperature scanning tunneling microscopy, from thermally stable liquid to solid phases as the coverage increases. Statistical analysis of the intermolecular interaction potential reveals that the repulsive dipole-dipole interaction induced by interfacial charge transfer and substrate-mediated interactions play important roles in stabilizing the liquid C60F48 phases. Theoretical calculations further suggest that the dipole moment per C60F48 molecule varies with the surface molecule density, and the liquid-solid transformation could be understood from the perspective of the thermodynamic free energy for open systems. This study offers insights into the growth behavior at 2D organic/TMD hybrid heterointerfaces.

40 CFR 97.102 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-07-01

..., petroleum, coal, or any form of solid, liquid, or gaseous fuel derived from such material. Fossil-fuel-fired... enclosed fossil- or other-fuel-fired combustion device used to produce heat and to transfer heat to... means a stationary, fossil-fuel-fired boiler or stationary, fossil-fuel-fired combustion turbine: (1...

40 CFR 97.102 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-07-01

..., petroleum, coal, or any form of solid, liquid, or gaseous fuel derived from such material. Fossil-fuel-fired... enclosed fossil- or other-fuel-fired combustion device used to produce heat and to transfer heat to... means a stationary, fossil-fuel-fired boiler or stationary, fossil-fuel-fired combustion turbine: (1...

40 CFR 97.102 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-07-01

..., petroleum, coal, or any form of solid, liquid, or gaseous fuel derived from such material. Fossil-fuel-fired... enclosed fossil- or other-fuel-fired combustion device used to produce heat and to transfer heat to... means a stationary, fossil-fuel-fired boiler or stationary, fossil-fuel-fired combustion turbine: (1...

40 CFR 97.102 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-07-01

..., petroleum, coal, or any form of solid, liquid, or gaseous fuel derived from such material. Fossil-fuel-fired... enclosed fossil- or other-fuel-fired combustion device used to produce heat and to transfer heat to... means a stationary, fossil-fuel-fired boiler or stationary, fossil-fuel-fired combustion turbine: (1...

40 CFR 97.102 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-07-01

..., petroleum, coal, or any form of solid, liquid, or gaseous fuel derived from such material. Fossil-fuel-fired... enclosed fossil- or other-fuel-fired combustion device used to produce heat and to transfer heat to... means a stationary, fossil-fuel-fired boiler or stationary, fossil-fuel-fired combustion turbine: (1...

Trickle-bed root culture bioreactor design and scale-up: growth, fluid-dynamics, and oxygen mass transfer.

PubMed

Ramakrishnan, Divakar; Curtis, Wayne R

2004-10-20

Trickle-bed root culture reactors are shown to achieve tissue concentrations as high as 36 g DW/L (752 g FW/L) at a scale of 14 L. Root growth rate in a 1.6-L reactor configuration with improved operational conditions is shown to be indistinguishable from the laboratory-scale benchmark, the shaker flask (mu=0.33 day(-1)). These results demonstrate that trickle-bed reactor systems can sustain tissue concentrations, growth rates and volumetric biomass productivities substantially higher than other reported bioreactor configurations. Mass transfer and fluid dynamics are characterized in trickle-bed root reactors to identify appropriate operating conditions and scale-up criteria. Root tissue respiration goes through a minimum with increasing liquid flow, which is qualitatively consistent with traditional trickle-bed performance. However, liquid hold-up is much higher than traditional trickle-beds and alternative correlations based on liquid hold-up per unit tissue mass are required to account for large changes in biomass volume fraction. Bioreactor characterization is sufficient to carry out preliminary design calculations that indicate scale-up feasibility to at least 10,000 liters.

Numerical Modeling of Conjugate Heat Transfer in Fluid Network

NASA Technical Reports Server (NTRS)

Majumdar, Alok

2004-01-01

Fluid network modeling with conjugate heat transfer has many applications in Aerospace engineering. In modeling unsteady flow with heat transfer, it is important to know the variation of wall temperature in time and space to calculate heat transfer between solid to fluid. Since wall temperature is a function of flow, a coupled analysis of temperature of solid and fluid is necessary. In cryogenic applications, modeling of conjugate heat transfer is of great importance to correctly predict boil-off rate in propellant tanks and chill down of transfer lines. In TFAWS 2003, the present author delivered a paper to describe a general-purpose computer program, GFSSP (Generalized Fluid System Simulation Program). GFSSP calculates flow distribution in complex flow circuit for compressible/incompressible, with or without heat transfer or phase change in all real fluids or mixtures. The flow circuit constitutes of fluid nodes and branches. The mass, energy and specie conservation equations are solved at the nodes where as momentum conservation equations are solved at the branches. The proposed paper describes the extension of GFSSP to model conjugate heat transfer. The network also includes solid nodes and conductors in addition to fluid nodes and branches. The energy conservation equations for solid nodes solves to determine the temperatures of the solid nodes simultaneously with all conservation equations governing fluid flow. The numerical scheme accounts for conduction, convection and radiation heat transfer. The paper will also describe the applications of the code to predict chill down of cryogenic transfer line and boil-off rate of cryogenic propellant storage tank.

Measurement of thyroxine and its glucuronide in municipal wastewater and solids using weak anion exchange solid phase extraction and ultrahigh performance liquid chromatography-tandem mass spectrometry.

PubMed

Brown, Alistair K; Wong, Charles S

2017-11-24

A solids extraction method, using sonication in combination with weak anion exchange solid phase extraction, was created to extract thyroxine (T4) and thyroxine-O-β-d-glucuronide (T4-Glc) simultaneously from wastewaters and sludges, and to quantify these compounds via reversed-phase ultra-high performance liquid chromatography-tandem mass spectrometry. The method limits of quantification were all in the low ng/g (dry weight solids) range for both T4 and T4-Glc: 2.13 and 2.63ng/g respectively in primary wastewater, 4.3 and 28.3ng/g for primary suspended solids, for 1.1 and 3.7ng/g for return activated sludge. Precision for measurements of T4 and T4-Glc were 2.6 and 6.5% (intraday) and 9.6 and 5.7% (interday) respectively, while linearity was 0.9967 and 0.9943 respectively. Overall recoveries for T4 and T4-Glc in primary suspended solids were 94% and 95%, and 86 and 101% in primary wastewater, respectively. Extraction efficiency tests using primary sludge determined that one methanol aliquot was sufficient during the extraction process as opposed to 2 or 3 aliquots. Mass loadings at the North Main Wastewater Treatment Plant in Winnipeg, Canada showed 316%, 714%, and 714% greater T4-Glc than T4 associated with the suspended solids of the primary, secondary, and final effluent respectively, yet 765% more T4 than T4-Glc associated with the solids of the mixed liquor. Moreover, 26% of T4 and 49% of T4-Glc were associated with the suspended solids during the treatment process. This method demonstrates the need to assess accurately both metabolite conjugates of contaminants of emerging concern, as well as the sorbed levels of particle-reactive analytes such as T4 in the aquatic environment. Copyright © 2017 Elsevier B.V. All rights reserved.

Accounting for the Effect of Noncondensing Gases on Interphasic Heat and Mass Transfer in the Two-Fluid Model Used in the KORSAR Code

NASA Astrophysics Data System (ADS)

Yudov, Yu. V.

2018-03-01

A model is presented of the interphasic heat and mass transfer in the presence of noncondensable gases for the KORSAR/GP design code. This code was developed by FGUP NITI and the special design bureau OKB Gidropress. It was certified by Rostekhnadzor in 2009 for numerical substantiation of the safety of reactor installations with VVER reactors. The model is based on the assumption that there are three types of interphasic heat and mass transfer of the vapor component: vapor condensation or evaporation on the interphase under any thermodynamic conditions of the phases, pool boiling of the liquid superheated above the saturation temperature at the total pressure, and spontaneous condensation in the volume of gas phase supercooled below the saturation temperature at the vapor partial pressure. Condensation and evaporation on the interphase continuously occur in a two-phase flow and control the time response of the interphase heat and mass transfer. Boiling and spontaneous condensation take place only at the metastable condition of the phases and run at a quite high speed. The procedure used for calculating condensation and evaporation on the interphase accounts for the combined diffusion and thermal resistance of mass transfer in all regimes of the two-phase flow. The proposed approach accounts for, in a natural manner, a decrease in the rate of steam condensation (or generation) in the presence of noncondensing components in the gas phase due to a decrease (or increase) in the interphase temperature relative to the saturation temperature at the vapor partial pressure. The model of the interphase heat transfer also accounts for the processes of dissolution or release of noncondensing components in or from the liquid. The gas concentration at the interphase and on the saturation curve is calculated by the Henry law. The mass transfer coefficient in gas dissolution is based on the heat and mass transfer analogy. Results are presented of the verification of the interphase heat and mass transfer used in the KORSAR/GP code based on the data on film condensation of steam-air flows in vertical pipes. The proposed model was also tested by solving a problem of nitrogen release from a supersaturated water solution.

Validation of a multi-phase plant-wide model for the description of the aeration process in a WWTP.

PubMed

Lizarralde, I; Fernández-Arévalo, T; Beltrán, S; Ayesa, E; Grau, P

2018-02-01

This paper introduces a new mathematical model built under the PC-PWM methodology to describe the aeration process in a full-scale WWTP. This methodology enables a systematic and rigorous incorporation of chemical and physico-chemical transformations into biochemical process models, particularly for the description of liquid-gas transfer to describe the aeration process. The mathematical model constructed is able to reproduce biological COD and nitrogen removal, liquid-gas transfer and chemical reactions. The capability of the model to describe the liquid-gas mass transfer has been tested by comparing simulated and experimental results in a full-scale WWTP. Finally, an exploration by simulation has been undertaken to show the potential of the mathematical model. Copyright © 2017 Elsevier Ltd. All rights reserved.

Demonstrating electromagnetic control of free-surface, liquid-metal flows relevant to fusion reactors

NASA Astrophysics Data System (ADS)

Hvasta, M. G.; Kolemen, E.; Fisher, A. E.; Ji, H.

2018-01-01

Plasma-facing components (PFC’s) made from solid materials may not be able to withstand the large heat and particle fluxes that will be produced within next-generation fusion reactors. To address the shortcomings of solid PFC’s, a variety of liquid-metal (LM) PFC concepts have been proposed. Many of the suggested LM-PFC designs rely on electromagnetic restraint (Lorentz force) to keep free-surface, liquid-metal flows adhered to the interior surfaces of a fusion reactor. However, there is very little, if any, experimental data demonstrating that free-surface, LM-PFC’s can actually be electromagnetically controlled. Therefore, in this study, electrical currents were injected into a free-surface liquid-metal that was flowing through a uniform magnetic field. The resultant Lorentz force generated within the liquid-metal affected the velocity and depth of the flow in a controllable manner that closely matched theoretical predictions. These results show the promise of electromagnetic control for LM-PFC’s and suggest that electromagnetic control could be further developed to adjust liquid-metal nozzle output, prevent splashing within a tokamak, and alter heat transfer properties for a wide-range of liquid-metal systems.

Demonstrating electromagnetic control of free-surface, liquid-metal flows relevant to fusion reactors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hvasta, Michael George; Kolemen, Egemen; Fisher, Adam

Plasma-facing components (PFC's) made from solid materials may not be able to withstand the large heat and particle fluxes that will be produced within next-generation fusion reactors. To address the shortcomings of solid PFC's, a variety of liquid-metal (LM) PFC concepts have been proposed. Many of the suggested LM-PFC designs rely on electromagnetic restraint (Lorentz force) to keep free-surface, liquid-metal flows adhered to the interior surfaces of a fusion reactor. However, there is very little, if any, experimental data demonstrating that free-surface, LM-PFC's can actually be electromagnetically controlled. Therefore, in this study, electrical currents were injected into a free-surface liquid-metalmore » that was flowing through a uniform magnetic field. The resultant Lorentz force generated within the liquid-metal affected the velocity and depth of the flow in a controllable manner that closely matched theoretical predictions. Furthermore, these results show the promise of electromagnetic control for LM-PFC's and suggest that electromagnetic control could be further developed to adjust liquid-metal nozzle output, prevent splashing within a tokamak, and alter heat transfer properties for a wide-range of liquid-metal systems.« less

Demonstrating electromagnetic control of free-surface, liquid-metal flows relevant to fusion reactors

DOE PAGES

Hvasta, Michael George; Kolemen, Egemen; Fisher, Adam; ...

2017-10-13

Plasma-facing components (PFC's) made from solid materials may not be able to withstand the large heat and particle fluxes that will be produced within next-generation fusion reactors. To address the shortcomings of solid PFC's, a variety of liquid-metal (LM) PFC concepts have been proposed. Many of the suggested LM-PFC designs rely on electromagnetic restraint (Lorentz force) to keep free-surface, liquid-metal flows adhered to the interior surfaces of a fusion reactor. However, there is very little, if any, experimental data demonstrating that free-surface, LM-PFC's can actually be electromagnetically controlled. Therefore, in this study, electrical currents were injected into a free-surface liquid-metalmore » that was flowing through a uniform magnetic field. The resultant Lorentz force generated within the liquid-metal affected the velocity and depth of the flow in a controllable manner that closely matched theoretical predictions. Furthermore, these results show the promise of electromagnetic control for LM-PFC's and suggest that electromagnetic control could be further developed to adjust liquid-metal nozzle output, prevent splashing within a tokamak, and alter heat transfer properties for a wide-range of liquid-metal systems.« less

Sugars and adiposity: the long-term effects of consuming added and naturally occurring sugars in foods and in beverages.

PubMed

Lee, A K; Chowdhury, R; Welsh, J A

2015-10-01

The aim of this study was to determine if the association with adiposity varies by the type (added vs. naturally occurring) and form (liquid vs. solid) of dietary sugars consumed. Data from the 10-year National Heart, Lung, and Blood Institute (NHLBI) Growth and Health Study ( n  = 2,021 girls aged 9-10 years at baseline; n  = 5,156 paired observations) were used. Using mixed linear models, 1-year changes in sugar intake, body mass index z -score (BMI z ) and waist circumference (WC) were assessed. The results showed mean daily added sugar (AS) intake: 10.3 tsp (41 g) liquid; 11.6 tsp (46 g) solid and naturally occurring sugar intake: 2.6 tsp (10 g) liquid; 2.2 tsp (9 g) solid. Before total energy adjustment, each additional teaspoon of liquid AS was associated with a 0.222-mm increase in WC ( p  = 0.0003) and a 0.002 increase in BMI z ( p  = 0.003). Each teaspoon of solid AS was associated with a 0.126-mm increase in WC ( p  = 0.03) and a 0.001 increase in BMI z ( p  = 0.03). Adjusting for total energy, this association was maintained only between liquid AS and WC among all and between solid AS and WC among those overweight/obese only. There was no significant association with naturally occurring sugar. These findings demonstrate to suggest a positive association between AS intake (liquid and solid) and BMI that is mediated by total energy intake and an association with WC that is independent of it.

Sugars and adiposity: the long‐term effects of consuming added and naturally occurring sugars in foods and in beverages

PubMed Central

Lee, A. K.; Chowdhury, R.

2015-01-01

Summary Objective The aim of this study was to determine if the association with adiposity varies by the type (added vs. naturally occurring) and form (liquid vs. solid) of dietary sugars consumed. Methods Data from the 10‐year National Heart, Lung, and Blood Institute (NHLBI) Growth and Health Study (n = 2,021 girls aged 9–10 years at baseline; n = 5,156 paired observations) were used. Using mixed linear models, 1‐year changes in sugar intake, body mass index z‐score (BMIz) and waist circumference (WC) were assessed. Results The results showed mean daily added sugar (AS) intake: 10.3 tsp (41 g) liquid; 11.6 tsp (46 g) solid and naturally occurring sugar intake: 2.6 tsp (10 g) liquid; 2.2 tsp (9 g) solid. Before total energy adjustment, each additional teaspoon of liquid AS was associated with a 0.222‐mm increase in WC (p = 0.0003) and a 0.002 increase in BMIz (p = 0.003). Each teaspoon of solid AS was associated with a 0.126‐mm increase in WC (p = 0.03) and a 0.001 increase in BMIz (p = 0.03). Adjusting for total energy, this association was maintained only between liquid AS and WC among all and between solid AS and WC among those overweight/obese only. There was no significant association with naturally occurring sugar. Conclusions These findings demonstrate to suggest a positive association between AS intake (liquid and solid) and BMI that is mediated by total energy intake and an association with WC that is independent of it. PMID:27774248

Method development for the analysis of ionophore antimicrobials in dairy manure to assess removal within a membrane-based treatment system.

PubMed

Hurst, Jerod J; Wallace, Josh S; Aga, Diana S

2018-04-01

Ionophore antimicrobials are heavily used in the livestock industries, both for preventing animal infection by coccidia protozoa and for increasing feed efficiency. Ionophores are excreted mostly unmetabolized and are released into the environment when manure is land-applied to fertilize croplands. Here, an analytical method was optimized to study the occurrences of five ionophore residues (monensin, lasalocid, maduramycin, salinomycin, and narasin) in dairy manure after solid-liquid separation and further treatment of the liquid manure by a membrane-based treatment system. Ionophore residues from the separated solid manure (dewatered manure) and suspended solids of manure slurry samples were extracted using ultrasonication with methanol, followed by sample clean-up using solid phase extraction (SPE) and subsequent analysis via liquid chromatography-tandem mass spectrometry (LC-MS/MS). The use of an ethyl acetate and methanol (1:1 v:v) mixture as an SPE eluent resulted in higher recoveries and lower method quantitation limits (MQL), when compared to using methanol. Overall recoveries from separated solid manure ranged from 73 to 134%. Liquid manure fractions were diluted with Nanopure™ water and cleaned up using SPE, where recoveries ranged from 51 to 100%. The developed extraction and LC-MS/MS methods were applied to analyze dairy manure samples subjected to an advanced manure treatment process involving a membrane-based filtration step (reverse osmosis). Monensin and lasalocid were detected at higher concentrations in the suspended solid fractions (4.40-420 ng/g for lasalocid and 85-1950 ng/g for monensin) compared to the liquid fractions (

Determination of type A trichothecenes in coix seed by magnetic solid-phase extraction based on magnetic multi-walled carbon nanotubes coupled with ultra-high performance liquid chromatography-tandem mass spectrometry.

PubMed

Dong, Maofeng; Si, Wenshuai; Wang, Weimin; Bai, Bing; Nie, Dongxia; Song, Weiguo; Zhao, Zhihui; Guo, Yirong; Han, Zheng

2016-09-01

Magnetic solid-phase extraction (m-SPE) is a promising sample preparation approach due to its convenience, speed, and simplicity. For the first time, a rapid and reliable m-SPE approach using magnetic multi-walled carbon nanotubes (m-MWCNTs) as the adsorbent was proposed for purification of type A trichothecenes including T-2 toxins (T2), HT-2 toxins (HT-2), diacetoxyscirpenol (DAS), and neosolaniol (NEO) in coix seed. The m-MWCNTs were synthesized by assembling the magnetic nanoparticles (Fe3O4) with MWCNTs by sonication through an aggregation wrap mechanism, and characterized by transmission electron microscope. Several key parameters affecting the performance of the procedure were extensively investigated including extraction solutions, desorption solvents, and m-MWCNT amounts. Under the optimal sample preparation conditions followed by analysis with ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS), high sensitivity (limit of quantification in the range of 0.3-1.5 μg kg(-1)), good linearity (R (2) > 0.99), satisfactory recovery (73.6-90.6 %), and acceptable precision (≤2.5 %) were obtained. The analytical performance of the developed method has also been successfully evaluated in real coix seed samples. Graphical Abstract Flow chart of determination of type A trichothecenes in coix seed by magnetic solid-phase extraction coupled with ultra-high performance liquid chromatography-tandem mass spectrometry.

Disposal of radioactive iodine in space

NASA Technical Reports Server (NTRS)

Burns, R. E.; Defield, J. G.

1978-01-01

The possibility of space disposal of iodine waste from nuclear power reactors is investigated. The space transportation system utilized relies upon the space shuttle, a liquid hydrogen/liquid oxygen orbit transfer vehicle, and a solid propellant final stage. The iodine is assumed to be in the form of either an iodide or an iodate, and calculations assume that the final destination is either solar orbit or solar system escape. It is concluded that space disposal of iodine is feasible.

Gravity assisted recovery of liquid xenon at large mass flow rates

NASA Astrophysics Data System (ADS)

Virone, L.; Acounis, S.; Beaupère, N.; Beney, J.-L.; Bert, J.; Bouvier, S.; Briend, P.; Butterworth, J.; Carlier, T.; Chérel, M.; Crespi, P.; Cussonneau, J.-P.; Diglio, S.; Manzano, L. Gallego; Giovagnoli, D.; Gossiaux, P.-B.; Kraeber-Bodéré, F.; Ray, P. Le; Lefèvre, F.; Marty, P.; Masbou, J.; Morteau, E.; Picard, G.; Roy, D.; Staempflin, M.; Stutzmann, J.-S.; Visvikis, D.; Xing, Y.; Zhu, Y.; Thers, D.

2018-06-01

We report on a liquid xenon gravity assisted recovery method for nuclear medical imaging applications. The experimental setup consists of an elevated detector enclosed in a cryostat connected to a storage tank called ReStoX. Both elements are part of XEMIS2 (XEnon Medical Imaging System): an innovative medical imaging facility for pre-clinical research that uses pure liquid xenon as detection medium. Tests based on liquid xenon transfer from the detector to ReStoX have been successfully performed showing that an unprecedented mass flow rate close to 1 ton per hour can be reached. This promising achievement as well as future areas of improvement will be discussed in this paper.

Liquid-liquid and solid-phase extractions of phenols from virgin olive oil and their separation by chromatographic and electrophoretic methods.

PubMed

Bendini, Alessandra; Bonoli, Matteo; Cerretani, Lorenzo; Biguzzi, Barbara; Lercker, Giovanni; Toschi, Tullia Gallina

2003-01-24

The high oxidative stability of virgin olive oil is related to its high monounsaturated/polyunsaturated ratio and to the presence of antioxidant compounds, such as tocopherols and phenols. In this paper, the isolation of phenolic compounds from virgin olive oil, by different methods, was tested and discussed. Particularly liquid-liquid and solid-phase extraction methods were compared, assaying, for the latter, three stationary phases (C8, C18 and Diol) and several elution mixtures. Quantification of phenolic and o-diphenolic substances in the extracts was performed by the traditional Folin-Ciocalteau method and the sodium molybdate reaction, respectively. Furthermore, the quantification of phenolic compounds in the extracts and in a standard mixture was carried out both with diode array and mass spectrometric detection and capillary zone electrophoresis.

In vitro propagation via organogenesis and synthetic seeds of Urginea altissima (L.f.) Baker: a threatened medicinal plant.

PubMed

Baskaran, Ponnusamy; Kumari, Aloka; Van Staden, Johannes

2018-01-01

Efficient in vitro propagation systems via organogenesis and synthetic seeds were developed for the first time for conservation and commercial propagation from leaf or longitudinal thin cell layer (lTCL) leaf or shoot-tip explants of Urginea altissima . Various plant growth regulators and phloroglucinol were used in semi-solid and liquid Murashige and Skoog (MS) medium to establish multiplication of shoots and roots for in vitro regeneration. Of the various treatments, the highest number of shoots (17.4 per lTCL leaf explant) was obtained on liquid MS medium supplemented with 10 µM meta -Topolin ( m T) and 2 µM benzyladenine followed by transferal to semi-solid MS media. The shoot tips were encapsulated with liquid MS medium plus 3% (w/v) sodium alginate and 100 mM calcium chloride. Adventitious shoot regeneration (91.0%; 12.6 shoots per synthetic seed) of synthetic seeds was achieved on semi-solid MS medium supplemented with 10 µM m T and 2 µM naphthaleneacetic acid (NAA) after 15 days of storage in darkness at 25 ± 2 °C. Regenerated shoots rooted (9.8 roots per shoot; 6.5 cm long) efficiently when transferred to 5 µM indole-3-butyric acid and 2.5 µM NAA. All the plantlets were successfully acclimatized (100%) in a vermiculite:soil (1:1 v/v) mixture in the greenhouse.

Colloid-Interface-Assisted Laser Irradiation of Nanocrystals Superlattices to be Scalable Plasmonic Superstructures with Novel Activities.

PubMed

Huang, Liu; Wan, Xiaodong; Rong, Hongpan; Yao, Yuan; Xu, Meng; Liu, Jia; Ji, Muwei; Liu, Jiajia; Jiang, Lan; Zhang, Jiatao

2018-04-01

High-efficient charge and energy transfer between nanocrystals (NCs) in a bottom-up assembly are hard to achieve, resulting in an obstacle in application. Instead of the ligands exchange strategies, the advantage of a continuous laser is taken with optimal wavelength and power to irradiate the film-scale NCs superlattices at solid-liquid interfaces. Owing to the Au-based NCs' surface plasmon resonance (SPR) effect, the gentle laser irradiation leads the Au NCs or Au@CdS core/shell NCs to attach each other with controlled pattern at the interfaces between solid NCs phase and liquid ethanol/ethylene glycol. A continuous wave 532 nm laser (6.68-13.37 W cm -2 ), to control Au-based superlattices, is used to form the monolayer with uniformly reduced interparticle distance followed by welded superstructures. Considering the size effect to Au NCs' melting, when decreasing the Au NCs size to ≈5 nm, stronger welding nanostructures are obtained with diverse unprecedented shapes which cannot be achieved by normal colloidal synthesis. With the help of facile scale-up and formation at solid-liquid interfaces, and a good connection of crystalline between NCs, the obtained plasmonic superstructured films that could be facilely transferred onto different substrates exhibit broad SPR absorption in the visible and near-infrared regime, enhanced electric conductivities, and wide applications as surface enhanced Raman scattering (SERS)-active substrates. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Method for simultaneous measurement of mass loading and fluid property changes using a quartz crystal microbalance

DOEpatents

Granstaff, V.E.; Martin, S.J.

1993-04-13

A method is described, using a quartz crystal microbalance, to obtain simultaneous measurement of solid mass accumulation and changes in liquid density-viscosity product. The simultaneous real-time measurements of electrical parameters yields that changes in surface mass can be differentiated from changes in solution properties. Two methods to obtain the admittance/frequency data are employed.

Hybrid Encapsulated Ionic Liquids for Post-Combustion Carbon Dioxide (CO 2) Capture

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brennecke, Joan F; Degnan, Jr, Thomas Francis; McCready, Mark J.

Ionic liquids (ILs) and Phase Change Ionic Liquids (PCILs) are excellent materials for selective removal of carbon dioxide from dilute post-combustion streams. However, they are typically characterized as having high viscosities, which impairs their effectiveness due to mass transfer limitations, caused by the high viscosities. In this project, we are examining the benefits of encapsulating ILs and PCILs in thin polymeric shells to produce particles of approximately 100 to 600 µm in diameter that can be used in a fluidized bed absorber. The particles are produced by microencapsulation of the ILs and PCILs in CO 2-permeable polymer shells. Here wemore » report on the encapsulation of the IL and PCIL materials, thermodynamic testing of the encapsulated materials, mass transfer measurements in both a fluidized bed and a packed bed, determination of the effect of impurities (SO 2, NO x and water) on the free and encapsulated IL and PCIL, recyclability of the CO 2 uptake, selection and synthesis of kg quantities of the IL and PCIL, identification of scale-up methods for encapsulation and production of a kg quantity of the PCIL, construction and shakedown of the laboratory scale unit to test the encapsulated particles for CO 2 capture ability and efficiency, use of our mass transfer model to predict mass transfer and identify optimal properties of the encapsulated particles, and initial testing of the encapsulated particles in the laboratory scale unit. We also show our attempts at developing shell materials that are resistant to water permeation. Overall, we have shown that the selected IL and PCIL can be successfully encapsulated in polymer shells and the methods scaled up to production levels. The IL/PCIL and encapsulated IL/PCIL react irreversibly with SO 2 and NO x so the CO 2 capture unit would need to be placed after the flue gas desulfurization and NO x reduction units. However, the reaction with CO 2 in the presence of water is completely reversible. Therefore, it is not necessary to exclude water from the capsules. Mass transfer in the fluidized and packed beds confirm that the fluidized bed arrangement is preferred and that the mass transfer can be predicted accurately by the rate based model that we have developed. Absorption and desorption experiments in the laboratory scale unit show good uptake and recyclability.« less

Mass transfer inside a flux hood for the sampling of gaseous emissions from liquid surfaces - Experimental assessment and emission rate rescaling

NASA Astrophysics Data System (ADS)

Prata, Ademir A.; Lucernoni, Federico; Santos, Jane M.; Capelli, Laura; Sironi, Selena; Le-Minh, Nhat; Stuetz, Richard M.

2018-04-01

This study assesses the mass transfer of compounds inside the US EPA flux hood, one of the enclosure devices most commonly employed for the direct measurement of atmospheric emissions from liquid surfaces in wastewater treatment plants (WWTPs). Experiments comprised the evaporation of water and the volatilisation of a range of volatile organic compounds (VOCs). Special attention was given to the evaluation of the mass transfer coefficients in the microenvironment created by the flux hood and the effects of concentration build up in the hood's headspace. The VOCs emission rates and the water evaporation rates generally increased with the sweep air flow rate, as did the mass transfer coefficients for all compounds. The emission of compounds whose volatilisation is significantly influenced by the gas phase was greatly affected by concentration build up, whereas this effect was not significant for liquid phase-controlled compounds. The gas-film mass transfer coefficient (kG) estimated inside the US EPA flux hood was of the same order as the respective kG reported in the literature for wind tunnel-type devices, but the emission rates measured by the flux hood can be expected to be lower, due to the concentration build-up. Compared against an emission model for the passive surfaces in WWTPs, the mass transfer of acetic acid (representing a gas phase-dominated compound) inside the US EPA flux hood was equivalent to conditions of wind speeds at 10 m height (U10) of 0.27, 0.51 and 0.99 m s-1, respectively, for sweep air flow rates of 2, 5 and 10 L min-1. On the other hand, for higher wind speeds, the emission rates of gas phase-controlled compounds obtained with the flux hood can be considerably underestimated: for instance, at U10 = 5 m s-1, the emission rates of acetic acid inside the flux hood would be approximately 23, 12 and 6 times lower than the emission rates in the field, for sweep air flow rates of 2, 5 and 10 L min-1, respectively. A procedure is presented in order to scale the emission rates of these compounds measured with the flux hood to field conditions of higher winds.